WorldWideScience

Sample records for two-color laser ranging

  1. Two dye combinations suitable for two-color/two-dye laser-induced fluorescence thermography for ethanol

    Science.gov (United States)

    Fenner, Andreas; Stephan, Peter

    2017-06-01

    This paper presents two dye combinations suitable for two-color/two-dye laser-induced fluorescence thermography for ethanol. Besides the temperature dependency of the fluorescence, the influences of laser fluence, dye concentration, pressure, dissolved air, and photobleaching are also discussed. The experimental data are compared with models and data available in literature. Based on this, parameter ranges for two-color/two-dye laser-induced fluorescence thermography applications can be determined.

  2. Low-temperature characteristics of two-color InAs/InP quantum dots laser

    Institute of Scientific and Technical Information of China (English)

    Shiguo Li; Qian Gong; Xinzhong Wang; Li Yue; Oingbo Liu; Hailong Wang

    2012-01-01

    We report on the lasing characteristics of a two-color InAs/InP quantum dots (QDs) laser at a low temperature.Two lasing peaks with a tunable gap are simultaneously observed.At a low temperature of 80 K,a tunable range greater than a 20-nm wavelength is demonstrated by varying the injection current from 30 to 500 mA.Under a special condition,we even observe three lasing peaks,which are in contrast to those observed at room temperature.The temperature coefficient of the lasing wavelength was obtained for the two colors in the 80-280 K temperature range,which is lower than that of the reference quantum well (QW) laser working in the same wavelength region.

  3. Development of two color laser diagnostics for the ITER poloidal polarimeter.

    Science.gov (United States)

    Kawahata, K; Akiyama, T; Tanaka, K; Nakayama, K; Okajima, S

    2010-10-01

    Two color laser diagnostics using terahertz laser sources are under development for a high performance operation of the Large Helical Device and for future fusion devices such as ITER. So far, we have achieved high power laser oscillation lines simultaneously oscillating at 57.2 and 47.7 μm by using a twin optically pumped CH(3)OD laser, and confirmed the original function, compensation of mechanical vibration, of the two color laser interferometer. In this article, application of the two color laser diagnostics to the ITER poloidal polarimeter and recent hardware developments will be described.

  4. Enhanced hole boring with two-color relativistic laser pulses in the fast ignition scheme

    Science.gov (United States)

    Yu, Changhai; Deng, Aihua; Tian, Ye; Li, Wentao; Wang, Wentao; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Liu, Jiansheng

    2016-08-01

    A scheme of using two-color laser pulses for hole boring into overdense plasma as well as energy transfer into electron and ion beams has been studied using particle-in-cell simulations. Following an ultra-short ultra-intense hole-boring laser pulse with a short central wavelength in extreme ultra-violet range, the main infrared driving laser pulse can be guided in the hollow channel preformed by the former laser and propagate much deeper into an overdense plasma, as compared to the case using the infrared laser only. In addition to efficiently transferring the main driving laser energy into energetic electrons and ions generation deep inside the overdense plasma, the ion beam divergence can be greatly reduced. The results might be beneficial for the fast ignition concept of inertial confinement fusion.

  5. Two-Color Fabry-Perot Laser Diode with THz Primary Mode Spacing

    CERN Document Server

    O'Brien, S; Buckley, K; Fehse, R; Amann, A; O'Reilly, E P; Barry, L P; Anandarajah, P; Patchell, J; O'Gorman, J

    2006-01-01

    A class of multiwavelength Fabry-Perot lasers is introduced where the spectrum is tailored through a non-periodic patterning of the cavity effective index. The cavity geometry is obtained using an inverse scattering approach and can be designed such that the spacing of discrete Fabry-Perot lasing modes is limited only by the bandwidth of the inverted gain medium. A specific two-color semiconductor laser with a mode spacing in the THz regime is designed, and measurements are presented demonstrating the simultaneous oscillation of the two wavelengths. The extension of the Fabry-Perot laser concept described presents significant new possibilities in laser cavity design.

  6. The research on two-color photon sources in infrared and X-ray ranges by compton scattering

    CERN Document Server

    Yu Zhao

    2001-01-01

    The generation of a two-color source of FEL light in both the infrared and soft X-ray ranges by intracavity Compton backscattering is demonstrated by the Beijing FEL facility. 1.20-1.35 keV soft X-rays are successfully extracted from the optical cavity of the FEL through a porous metallic mirror, while a 9-10 mu m FEL laser is output in the other dielectric mirror simultaneously. The average output flux of X-ray is 10 sup 2 -10 sup 3 photons/s when the average output FEL laser power is 6-20 mW. The experimental result allows us to envision a convenient way to expand the application areas of IR FEL facilities into X-ray or gamma-ray ranges.

  7. Controlling Nonsequential Double Ionization in Two-Color Circularly Polarized Femtosecond Laser Fields

    Science.gov (United States)

    Mancuso, Christopher A.; Dorney, Kevin M.; Hickstein, Daniel D.; Chaloupka, Jan L.; Ellis, Jennifer L.; Dollar, Franklin J.; Knut, Ronny; Grychtol, Patrik; Zusin, Dmitriy; Gentry, Christian; Gopalakrishnan, Maithreyi; Kapteyn, Henry C.; Murnane, Margaret M.

    2016-09-01

    Atoms undergoing strong-field ionization in two-color circularly polarized femtosecond laser fields exhibit unique two-dimensional photoelectron trajectories and can emit bright circularly polarized extreme ultraviolet and soft-x-ray beams. In this Letter, we present the first experimental observation of nonsequential double ionization in these tailored laser fields. Moreover, we can enhance or suppress nonsequential double ionization by changing the intensity ratio and helicity of the two driving laser fields to maximize or minimize high-energy electron-ion rescattering. Our experimental results are explained through classical simulations, which also provide insight into how to optimize the generation of circularly polarized high harmonic beams.

  8. Streaking temporal double slit interference by an orthogonal two-color laser field

    CERN Document Server

    Richter, Martin; Schöffler, Markus; Jahnke, Till; Schmidt, Lothar P H; Li, Min; Liu, Yunquan; Dörner, Reinhard

    2015-01-01

    We investigate electron momentum distributions from single ionization of Ar by two orthogonally polarized laser pulses of different color. The two-color scheme is used to experimentally control the interference between electron wave packets released at different times within one laser cycle. This intracycle interference pattern is typically hard to resolve in an experiment. With the two-color control scheme these features become the dominant contribution to the electron momentum distribution. Furthermore the second color can be used for streaking of the otherwise interfering wave packets establishing a which-way marker. Our investigation shows that the visibility of the interference fringes depends on the degree of the which-way information determined by the controllable phase between the two pulses.

  9. Two-color CO{sub 2}/HeNe laser interferometer for C-2 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Gornostaeva, O.; Deng, B. H.; Garate, E.; Gota, H.; Kinley, J.; Schroeder, J.; Tuszewski, M. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States)

    2010-10-15

    A six-channel two-color interferometer has been developed for plasma electron density measurements in the C-2 field reversed configuration experiment. A CO{sub 2} laser is utilized as the main probe beams, while copropagating visible HeNe laser beams are mainly sensitive to vibration. Density measurements in C-2 plasmas have shown that this is a reliable turn-key system. The maximum residual phase noise after vibration compensation is less than {+-}5 deg., corresponding to a line integral density of 3x10{sup 18} m{sup -2}. The time resolution for routine operation is 2 {mu}s.

  10. Tomographic imaging of asymmetric molecular orbitals with a two-color multicycle laser field

    CERN Document Server

    Qin, Meiyan; Zhang, Qingbin; Lu, Peixiang

    2013-01-01

    We theoretically demonstrate a scheme for tomographic reconstruction of asymmetric molecular orbitals based on high-order harmonic generation with a two-color multicycle laser field. It is shown that by adjusting the relative phase of the two fields, the returning electrons can be forced to recollide from one direction for all the orientations of molecules. Thus the reconstruction of the asymmetric orbitals can be carried out with multicycle laser field. This releases the stringent requirement of a single-cycle pulse with a stabilized and controllable carrier-envelop phase for the tomographic imaging of asymmetric molecular orbitals.

  11. Two-color CO2/HeNe laser interferometer for C-2 experiment.

    Science.gov (United States)

    Gornostaeva, O; Deng, B H; Garate, E; Gota, H; Kinley, J; Schroeder, J; Tuszewski, M

    2010-10-01

    A six-channel two-color interferometer has been developed for plasma electron density measurements in the C-2 field reversed configuration experiment. A CO(2) laser is utilized as the main probe beams, while copropagating visible HeNe laser beams are mainly sensitive to vibration. Density measurements in C-2 plasmas have shown that this is a reliable turn-key system. The maximum residual phase noise after vibration compensation is less than ±5°, corresponding to a line integral density of 3×10(18) m(-2). The time resolution for routine operation is 2 μs.

  12. Mechanisms of two-color laser-induced field-free molecular orientation.

    Science.gov (United States)

    Spanner, Michael; Patchkovskii, Serguei; Frumker, Eugene; Corkum, Paul

    2012-09-14

    Two mechanisms of two-color (ω+2ω) laser-induced field-free molecular orientation, based on the hyperpolarizability and ionization depletion, are explored and compared. The CO molecule is used as a computational example. While the hyperpolarizability mechanism generates small amounts of orientation at intensities below the ionization threshold, ionization depletion quickly becomes the dominant mechanism as soon as ionizing intensities are reached. Only the ionization mechanism leads to substantial orientation (e.g., on the order of ≳0.1). For intensities typical of laser-induced molecular alignment and orientation experiments, the two mechanisms lead to robust, characteristic timings of the field-free orientation wave-packet revivals relative to the alignment revivals and the revival time. The revival timings can be used to detect the active orientation mechanism experimentally.

  13. THz wave emission from argon in two-color laser field

    Institute of Scientific and Technical Information of China (English)

    杜玲玲; 赵松峰; 周效信; 赵增秀

    2015-01-01

    Terahertz (THz) wave emission from argon atom in a two-color laser pulses is studied numerically by solving the one-dimensional (1D) time-dependent Schr ¨odinger equation. The THz spectra we obtained include both discontinuous and continuum ones. By using the special basis functions that we previously proposed, our analysis points out that the discontinuous and continuum parts are contributed by bound–bound and continuum–continuum transition of atomic energy levels. Although the atomic wave function is strongly dressed during the interaction with laser fields, our identification for the discontinuous part of the THz wave shows that the transition between highly excited bound states can still be well described by the field-free basis function in the tunneling ionization regime.

  14. Generation of strong terahertz field from two-color laser filamentation and optical rectification

    Science.gov (United States)

    Kuk, Donghoon; Yoo, Yungjun; Oh, Taek Il; You, Yong Sing; Kim, Ki-Yong

    2015-04-01

    We have demonstrated strong-field (>8 MV/cm), high-peak-power (12 MW) THz generation with a bandwidth of >20 THz via two-color laser filamentation. Moderate average power (1.4 mW) is also achieved by using a cryogenically-cooled Ti:sapphire amplifier capable of producing 30 fs, 15 mJ pulses at a 1 kHz repetition rate. For maximal THz generation and transmission, we have used a combination of a thin dichroic waveplate and a large Brewster-angled silicon filter. Here we have used a thin BBO crystal for frequency doubling (800 nm to 400 nm) and observed strong terahertz emission from the crystal itself. We also find that this type of terahertz emission can be optimized to yield more output power compared to two-color photoionization. In both cases, we have used a microbolometer camera for real-time THz beam profiling. This cost-effective THz camera along with our intense THz sources can be a useful tool for nonlinear THz studies including broadband THz spectroscopy and imaging. Work supported by DOE, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. 014216-001.

  15. Remote creation of strong and coherent emissions in air with two-color ultrafast laser pulses

    CERN Document Server

    Yao, Jinping; Jing, Chenrui; Zeng, Bin; Chu, Wei; Ni, Jielei; Zhang, Haisu; Xie, Hongqiang; Zhang, Chaojin; Li, Helong; Xu, Huailiang; Chin, See Leang; Cheng, Ya; Xu, Zhizhan

    2012-01-01

    We experimentally demonstrate generation of strong narrow-bandwidth emissions with excellent coherent properties at ~391 nm and ~428 nm from molecular ions of nitrogen inside a femtosecond filament in air by an orthogonally polarized two-color driver field (i. e., 800 nm laser pulse and its second harmonic). The durations of the coherent emissions at 391 nm and 428 nm are measured to be ~2.4 ps and ~7.8 ps respectively, both of which are much longer than the duration of the pump and its second harmonic pulses. Furthermore, the measured temporal decay characteristics of the excited molecular systems suggest an "instantaneous" population inversion mechanism that may be achieved in molecular nitrogen ions at an ultrafast time scale comparable to the 800 nm pump pulse.

  16. Long-range predissociation in two-color photoassociation of ultracold Na atoms

    NARCIS (Netherlands)

    Molenaar, P.A.; Straten, P. van der; Heideman, H.G.M.

    1997-01-01

    We report two-color photo-associative ionization of sodium in a Magneto-Optical Trap. The experimental results yield information on both singly and doubly excited states. We find that the highest bound vibrational levels (v > 20) of the singly-excited 0^- g state predissociate into the 3²P3/2

  17. Laser-induced periodic surface structures on titanium upon single- and two-color femtosecond double-pulse irradiation.

    Science.gov (United States)

    Höhm, Sandra; Rosenfeld, Arkadi; Krüger, Jörg; Bonse, Jörn

    2015-10-05

    Single- and two-color double-fs-pulse experiments were performed on titanium to study the dynamics of the formation of laser-induced periodic surface structures (LIPSS). A Mach-Zehnder inter-ferometer generated polarization controlled (parallel or cross-polarized) double-pulse sequences in two configurations - either at 800 nm only, or at 400 and 800 nm wavelengths. The inter-pulse delays of the individual 50-fs pulses ranged up to some tens of picoseconds. Multiple of these single- or two-color double-fs-pulse sequences were collinearly focused by a spherical mirror to the sample surface. In both experimental configurations, the peak fluence of each individual pulse was kept below its respective ablation threshold and only the joint action of both pulses lead to the formation of LIPSS. Their resulting characteristics were analyzed by scanning electron microscopy and the periods were quantified by Fourier analyses. The LIPSS periods along with the orientation allow a clear identification of the pulse which dominates the energy coupling to the material. A plasmonic model successfully explains the delay-dependence of the LIPSS on titanium and confirms the importance of the ultrafast energy deposition stage for LIPSS formation.

  18. Frequency modulation of high-order harmonic generation in an orthogonally polarized two-color laser field.

    Science.gov (United States)

    Li, Guicun; Zheng, Yinghui; Ge, Xiaochun; Zeng, Zhinan; Li, Ruxin

    2016-08-08

    We have experimentally investigated the frequency modulation of high-order harmonics in an orthogonally polarized two-color laser field consisting of a mid-infrared 1800nm fundamental pulse and its second harmonic pulse. It is demonstrated that the high harmonic spectra can be fine-tuned as we slightly change the relative delay of the two-color laser pulses. By analyzing the relative frequency shift of each harmonic at different two-color delays, the nonadiabatic spectral shift induced by the rapid variation of the intensity-dependent intrinsic dipole phase can be distinguished from the blueshift induced by the change of the refractive index during self-phase modulation (SPM). Our comprehensive analysis shows that the frequency modulation pattern is a reflection of the average emission time of high-order harmonic generation (HHG), thus offering a simple method to fine-tune the spectra of the harmonics on a sub-cycle time scale.

  19. Generation of elliptically polarized nitrogen-ion laser fields using two-color femtosecond laser pulses

    CERN Document Server

    Li, Ziting; Chu, Wei; Xie, Hongqiang; Yao, Jinping; Li, Guihua; Qiao, Lingling; Wang, Zhanshan; Cheng, Ya

    2015-01-01

    We experimentally investigate generation of molecular nitrogen-ion lasers with two femtosecond laser pulses at different wavelengths. The first pulse serves as the pump which ionizes the nitrogen molecules and excites the molecular ions to excited electronic states. The second pulse serves as the probe which leads to stimulated emission from the excited molecular ions. We observe that changing the angle between the polarization directions of the two pulses gives rise to elliptically polarized molecular nitrogen-ion laser fields, which is interpreted as a result of strong birefringence of the gain medium near the wavelengths of the molecular nitrogen-ion laser.

  20. Laser-induced periodic surface structures on fused silica upon cross-polarized two-color double-fs-pulse irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Höhm, S., E-mail: hoehm@mbi-berlin.de.de [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Herzlieb, M.; Rosenfeld, A. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Krüger, J. [BAM Bundesanstalt für Materialforschung und–prüfung, Unter den Eichen 87, D-12205 Berlin (Germany); Bonse, J., E-mail: joern.bonse@bam.de [BAM Bundesanstalt für Materialforschung und–prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)

    2015-05-01

    Graphical abstract: - Highlights: • LIPSS formation on fused silica is studied upon cross-polarized two-color (400 and 800 nm) double-fs-pulse irradiation. • LIPSS orientation follows the polarization of the first pulse. • LIPSS periods are determined by the wavelength of the first pulse. • LIPSS area is increased for temporally overlapping pulses due to nonlinear absorption. - Abstract: The dynamics of the formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration) is studied by cross-polarized two-color double-fs-pulse experiments. In order to analyze the relevance of temporally distributed energy deposition in the early stage of LIPSS formation, a Mach-Zehnder interferometer was used for generating multiple double-pulse sequences at two different wavelengths (400 and 800 nm). The inter-pulse delay between the individual cross-polarized pulses of each sequence was systematically varied in the sub-ps range and the resulting LIPSS morphologies were characterized by scanning electron microscopy. It is found that the polarization of the first laser pulse arriving to the surface determines the orientation and the periodicity of the LIPSS. These two-color experiments further confirm the importance of the ultrafast energy deposition to the silica surface for LIPSS formation, particularly by the first laser pulse of each sequence. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS characteristics (period, orientation)

  1. Femtosecond laser-induced periodic surface structures on silicon upon polarization controlled two-color double-pulse irradiation.

    Science.gov (United States)

    Höhm, Sandra; Herzlieb, Marcel; Rosenfeld, Arkadi; Krüger, Jörg; Bonse, Jörn

    2015-01-12

    Two-color double-fs-pulse experiments were performed on silicon wafers to study the temporally distributed energy deposition in the formation of laser-induced periodic surface structures (LIPSS). A Mach-Zehnder interferometer generated parallel or cross-polarized double-pulse sequences at 400 and 800 nm wavelength, with inter-pulse delays up to a few picoseconds between the sub-ablation 50-fs-pulses. Multiple two-color double-pulse sequences were collinearly focused by a spherical mirror to the sample. The resulting LIPSS characteristics (periods, areas) were analyzed by scanning electron microscopy. A wavelength-dependent plasmonic mechanism is proposed to explain the delay-dependence of the LIPSS. These two-color experiments extend previous single-color studies and prove the importance of the ultrafast energy deposition for LIPSS formation.

  2. Channel-resolved subcycle interferences of electron wave packets emitted from H$_2$ in two-color laser fields

    CERN Document Server

    Xie, Xinhua; Kartashov, Daniil; Zhang, Li; Baltuška, Andrius; Kitzler, Markus

    2016-01-01

    We report on the observation of subcycle interferences of electron wave packets released during the strong field ionization of H$_2$ with cycle-shaped two-color laser fields. With a reaction microscope, channel-resolved photoelectron momentum distribution are obtained for different final products originating from single ionization of H$_2$. Our results show that the subcycle interference structures of electron wave packet are very sensitive to the cycle-shape of the two-color laser field. The reason is that the ionization time within an optical cycle is determined by the cycle-shape of the laser field. The subcycle interference structures can be further used to get the subcycle dynamics of molecules during strong field interaction.

  3. Spectral dynamics of THz pulses generated by two-color laser filaments in air: The role of Kerr nonlinearities and pump wavelength

    CERN Document Server

    Nguyen, A; Dechard, J; Thiele, I; Babushkin, I; Skupin, S; Berge, L

    2016-01-01

    We theoretically and numerically study the influence of both instantaneous and Raman-delayed Kerr nonlinearities as well as a long-wavelength pump in the terahertz (THz) emissions produced by two-color femtosecond filaments in air. Although the Raman-delayed nonlinearity induced by air molecules weakens THz generation, four-wave mixing is found to impact the THz spectra accumulated upon propagation via self-, cross-phase modulations and self-steepening. Besides, using the local current theory, we show that the scaling of laser-to-THz conversion efficiency with the fundamental laser wavelength strongly depends on the relative phase between the two colors, the pulse duration and shape, rendering a universal scaling law impossible. Scaling laws in powers of the pump wavelength may only provide a rough estimate of the increase in the THz yield. We confront these results with comprehensive numerical simulations of strongly focused pulses and of filaments propagating over meter-range distances.

  4. Ionization in Orthogonal Two-Color Laser Fields - Origin and Phase Dependence of Trajectory-Resolved Coulomb Effects

    CERN Document Server

    Richter, Martin; Schöffler, Markus; Jahnke, Till; Schmidt, Lothar Ph H; Dörner, Reinhard

    2016-01-01

    We report on electron momentum distributions from single ionization of Ar in strong orthogonally polarized two-color (OTC) laser fields measured with the COLTRIMS technique. We study the effect of Coulomb focusing whose signature is a cusp like feature in the center of the electron momentum spectrum. While the direct electrons show the expected strong dependence on the phase between the two colors, surprisingly the Coulomb focused structure is almost not influenced by the weak second harmonic streaking field. This effect is explained by the use of a CTMC simulation which describes the tunneled electron wave packet in terms of classical trajectories under the influence of the combined Coulomb- and OTC laser field. We find a subtle interplay between the initial momentum of the electron upon tunneling, the ionization phase and the action of the Coulomb field that makes the Coulomb focused part of the momentum spectrum apparently insensitive to the weaker streaking field.

  5. Improved treatment of the turning point in tunnel ionization of atoms in a low-frequency two color laser field

    Science.gov (United States)

    Petrović, V. M.; Miladinović, T. B.

    2016-12-01

    The tunneling photoionization rate for a two color (bichromatic) field consisting of coherent superposition of the fundamental laser field frequency ω and its second harmonic with frequency 2ω , was studied theoretically within the framework of the adiabatic Landau-Dykhne approach. Analytical expressions were derived for the case of fixed specified values of relative phase shift, \\varphi =0 between the harmonics of the incident bichromatic field.

  6. Formation of laser-induced periodic surface structures on fused silica upon two-color double-pulse irradiation

    Science.gov (United States)

    Höhm, S.; Herzlieb, M.; Rosenfeld, A.; Krüger, J.; Bonse, J.

    2013-12-01

    The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of fused silica with multiple irradiation sequences consisting of laser pulse pairs (50 fs single-pulse duration) of two different wavelengths (400 and 800 nm) is studied experimentally. Parallel polarized double-pulse sequences with a variable delay Δt between -10 and +10 ps and between the individual fs-laser pulses were used to investigate the LIPSS periods versus Δt. These two-color experiments reveal the importance of the ultrafast energy deposition to the silica surface by the first laser pulse for LIPSS formation. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS frequencies.

  7. Formation of laser-induced periodic surface structures on fused silica upon two-color double-pulse irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Höhm, S.; Herzlieb, M.; Rosenfeld, A. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Krüger, J.; Bonse, J. [BAM Bundesanstalt für Materialforschung und –prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)

    2013-12-16

    The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of fused silica with multiple irradiation sequences consisting of laser pulse pairs (50 fs single-pulse duration) of two different wavelengths (400 and 800 nm) is studied experimentally. Parallel polarized double-pulse sequences with a variable delay Δt between −10 and +10 ps and between the individual fs-laser pulses were used to investigate the LIPSS periods versus Δt. These two-color experiments reveal the importance of the ultrafast energy deposition to the silica surface by the first laser pulse for LIPSS formation. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS frequencies.

  8. Generation of an isolated sub-30 attosecond pulse in a two-color laser field and a static electric field

    Institute of Scientific and Technical Information of China (English)

    Zhang Gang-Tai; Bai Ting-Ting; Zhang Mei-Guang

    2012-01-01

    We theoretically investigate high-order harmonic generation(HHG)from a helium ion model in a two-color laser field,which is synthesized by a fundamental pulse and its second harmonic pulse.It is shown that a supercontinuum spectrum can be generated in the two-color field.However,the spectral intensity is very low,limiting the application of the generated attosecond(as)pulse.By adding a static electric field to the synthesized two-color field,not only is the ionization yield of electrons contributing to the harmonic emission remarkably increased,but also the quantum paths of the HHG can be significantly modulated.As a result,the extension and enhancement of the supercontinuum spectrum are achieved,producing an intense isolated 26-as pulse with a bandwidth of about 170.5 eV.In particular,we also analyse the influence of the laser parameters on the ultrabroad supercontinuum spectrum and isolated sub-30-as pulse generation.

  9. Matching-based fresh-slice method for generating two-color x-ray free-electron lasers

    Directory of Open Access Journals (Sweden)

    Weilun Qin

    2017-09-01

    Full Text Available Two-color high intensity x-ray free-electron lasers (FELs provide powerful tools for probing ultrafast dynamic systems. A novel concept of realizing fresh-slice two-color lasing through slice-dependent transverse mismatch has been proposed by one of the authors [Y. Chao, SLAC Report No. SLAC-PUB-16935, 2016]. In this paper we present a feasible example following this concept based on the Linac Coherent Light Source parameters. Time-dependent mismatch along the bunch is generated by a passive dechirper module and controlled by downstream matching sections, enabling FEL lasing at different wavelength with a split undulator configuration. Simulations for soft x-ray FELs show that tens of gigawatts pulses with femtosecond duration can be generated.

  10. Laser-induced periodic surface structures on fused silica upon cross-polarized two-color double-fs-pulse irradiation

    Science.gov (United States)

    Höhm, S.; Herzlieb, M.; Rosenfeld, A.; Krüger, J.; Bonse, J.

    2015-05-01

    The dynamics of the formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration) is studied by cross-polarized two-color double-fs-pulse experiments. In order to analyze the relevance of temporally distributed energy deposition in the early stage of LIPSS formation, a Mach-Zehnder interferometer was used for generating multiple double-pulse sequences at two different wavelengths (400 and 800 nm). The inter-pulse delay between the individual cross-polarized pulses of each sequence was systematically varied in the sub-ps range and the resulting LIPSS morphologies were characterized by scanning electron microscopy. It is found that the polarization of the first laser pulse arriving to the surface determines the orientation and the periodicity of the LIPSS. These two-color experiments further confirm the importance of the ultrafast energy deposition to the silica surface for LIPSS formation, particularly by the first laser pulse of each sequence. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS characteristics (period, orientation).

  11. Polarimetric, Two-Color, Photon-Counting Laser Altimeter Measurements of Forest Canopy Structure

    Science.gov (United States)

    Harding, David J.; Dabney, Philip W.; Valett, Susan

    2011-01-01

    Laser altimeter measurements of forest stands with distinct structures and compositions have been acquired at 532 nm (green) and 1064 nm (near-infrared) wavelengths and parallel and perpendicular polarization states using the Slope Imaging Multi-polarization Photon Counting Lidar (SIMPL). The micropulse, single photon ranging measurement approach employed by SIMPL provides canopy structure measurements with high vertical and spatial resolution. Using a height distribution analysis method adapted from conventional, 1064 nm, full-waveform lidar remote sensing, the sensitivity of two parameters commonly used for above-ground biomass estimation are compared as a function of wavelength. The results for the height of median energy (HOME) and canopy cover are for the most part very similar, indicating biomass estimations using lidars operating at green and near-infrared wavelengths will yield comparable estimates. The expected detection of increasing depolarization with depth into the canopies due to volume multiple-scattering was not observed, possibly due to the small laser footprint and the small detector field of view used in the SIMPL instrument. The results of this work provide pathfinder information for NASA's ICESat-2 mission that will employ a 532 nm, micropulse, photon counting laser altimeter.

  12. Terahertz radiation driven by two-color laser pulses at near-relativistic intensities: Competition between photoionization and wakefield effects.

    Science.gov (United States)

    González de Alaiza Martínez, P; Davoine, X; Debayle, A; Gremillet, L; Bergé, L

    2016-06-03

    We numerically investigate terahertz (THz) pulse generation by linearly-polarized, two-color femtosecond laser pulses in highly-ionized argon. Major processes consist of tunneling photoionization and ponderomotive forces associated with transverse and longitudinal field excitations. By means of two-dimensional particle-in-cell (PIC) simulations, we reveal the importance of photocurrent mechanisms besides transverse and longitudinal plasma waves for laser intensities >10(15) W/cm(2). We demonstrate the following. (i) With two-color pulses, photoionization prevails in the generation of GV/m THz fields up to 10(17) W/cm(2) laser intensities and suddenly loses efficiency near the relativistic threshold, as the outermost electron shell of ionized Ar atoms has been fully depleted. (ii) PIC results can be explained by a one-dimensional Maxwell-fluid model and its semi-analytical solutions, offering the first unified description of the main THz sources created in plasmas. (iii) The THz power emitted outside the plasma channel mostly originates from the transverse currents.

  13. Synthesis of Two-Color Laser Pulses for the Harmonic Cutoff Extension

    Science.gov (United States)

    Wang, Guo-Li; Zhou, Li-Hua; Zhao, Song-Feng; Zhou, Xiao-Xin

    2016-05-01

    Increasing simultaneously both the cutoff energy and efficiency is a big challenge to all applications of high-order harmonic generation (HHG). For this purpose, the shaping of the waveform of driving pulse is an alternative approach. Here, we show that the harmonic cutoff can be extended by about two times without reducing harmonic yield after considering macroscopic propagation effects, by adopting a practical way to synthesize two-color fields with fixed energy. Our results, combined with the experimental techniques, show the great potential of HHG as a tabletop light source. Supported by the National Natural Science Foundation of China under Grant Nos. 11264036, 11164025, 11364038, the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20116203120001, and the Basic Scientific Research Foundation for Institution of Higher Learning of Gansu Province

  14. Frequency doubler and two-color mode of operation at free electron laser FLASH2

    Science.gov (United States)

    Kuhlmann, M.; Schneidmiller, E. A.; Yurkov, M. V.

    2017-06-01

    We report on the results of the first operation of a frequency doubler at FLASH2. The scheme uses the feature of the variable gap of the undulator. Undulator is divided in two parts. The second part of the undulator is tuned to the double frequency of the first part. Modulated electron beam enters the second part of the undulator and generates radiation at the 2nd harmonic. Depending on a balance between the gain of undulator sections, frequency doubler allows operation in a two-color mode and operation at shorter wavelengths with respect to standard SASE scheme. The shortest wavelength of 3.1 nm (photon energy 400 eV) has been achieved at FLASH2 with frequency doubler scheme, which is significantly below the design value for the standard SASE option.

  15. Two-Color Laser High-Harmonic Generation in Cavitated Plasma Wakefields

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2016-10-03

    A method is proposed for producing coherent x-rays via high-harmonic generation using a laser interacting with highly-stripped ions in cavitated plasma wakefields. Two laser pulses of different colors are employed: a long-wavelength pulse for cavitation and a short-wavelength pulse for harmonic generation. This method enables efficient laser harmonic generation in the sub-nm wavelength regime.

  16. Intramolecular triplet energy transfer via higher triplet excited state during stepwise two-color two-laser irradiation.

    Science.gov (United States)

    Oseki, Yosuke; Fujitsuka, Mamoru; Sakamoto, Masanori; Majima, Tetsuro

    2007-10-01

    We studied the energy transfer processes in the molecular array consisting of pyrene (Py), biphenyl (Ph2), and bisphthalimidethiophene (ImT), (Py-Ph2)2-ImT, during two-color two-laser flash photolysis (2-LFP). The first laser irradiation predominantly generates ImT in the lowest triplet excited state (ImT(T1)) because of the efficient singlet energy transfer from Py in the lowest singlet excited state to ImT and, then, intersystem crossing of ImT. ImT(T1) was excited to the higher triplet excited state (Tn) with the second laser irradiation. Then, the triplet energy was rapidly transferred to Py via a two-step triplet energy transfer (TET) process through Ph2. The efficient generation of Py(T1) was suggested from the nanosecond-picosecond 2-LFP. The back-TET from Py(T1) to ImT was observed for several tens of microseconds after the second laser irradiation. The estimated intramolecular TET rate from Py(T1) to ImT was as slow as 3.1 x 104 s-1. Hence, long-lived Py(T1) was selectively and efficiently produced during the 2-LFP.

  17. Ultrafast molecular photoionization by two-color orthogonally polarized ultraviolet laser pulses: Effects of relative pulse phases

    Science.gov (United States)

    Yuan, Kai-Jun; Chelkowski, Szczepan; Bandrauk, André D.

    2017-09-01

    We present molecular photoionization by two-color 2ω1 =ω2 orthogonally polarized ultraviolet laser pulses. Simulations are performed on aligned H+ by numerically solving time-dependent Schrödinger equations. Two ionization processes with one ω2 photon interfering with two ω1 photon absorption are studied at different molecular alignments. Molecular frame photoelectron momentum and angular distributions exhibit asymmetries which are functions of the relative pulse phase. For resonant excitation processes by the ω1 pulse, symmetric distributions are obtained. An attosecond ionization model is adopted to describe the ultrafast ionization dynamics. The dependence of the ionization asymmetry on the molecular alignment allows to further monitor interference effects on orbital symmetry.

  18. Non-Sequential Double Ionization by Counter Rotating Circularly Polarized Two-Color Laser Fields

    CERN Document Server

    Eckart, S; Kunitski, M; Hartung, A; Rist, J; Henrichs, K; Schlott, N; Kang, H; Bauer, T; Sann, H; Schmidt, L Ph H; Schöffler, M; Jahnke, T; Dörner, R

    2016-01-01

    We report on non-sequential double ionization of Ar by a laser pulse consisting of two counter rotating circularly polarized fields (390 nm and 780 nm). The double ionization probability depends strongly on the relative intensity of the two fields and shows a "knee"-like structure as function of intensity. We conclude that double ionization is driven by a beam of nearly monoenergetic recolliding electrons, which can be controlled in intensity and energy by the field parameters. The electron momentum distributions show the recolliding electron as well as a second electron which escapes from an intermediate excited state of Ar$^+$.

  19. Two-color interferometer for the study of laser filamentation triggered electric discharges in air

    CERN Document Server

    Point, Guillaume; Arantchouk, Leonid; Carbonnel, Jérôme; Prade, Bernard; Mysyrowicz, André; Houard, Aurélien

    2014-01-01

    We present a space and time resolved interferometric plasma diagnostic for use on plasmas where neutral-bound electron contribution to the refractive index cannot be neglected. By recording simultaneously the plasma optical index at 532 and 1064 nm, we are able to extract independently the neutral and free electron density profiles. We report a phase resolution of 30 mrad, corresponding to a maximum resolution on the order of $4\\times10^{23}~\\mathrm{m}^{-3}$ for the electron density, and of $10^{24} ~ \\mathrm{m}^{-3}$ for the neutral density. The interferometer is demonstrated on centimeter-scale sparks triggered by laser filamentation in air with typical currents of a few tens of A.

  20. Picosecond sources for sub-centimeter laser ranging

    Science.gov (United States)

    Krebs, Danny J.; Dallas, Joseph; Seery, Bernard D.

    1992-01-01

    Some of the tradeoffs involved in selecting a laser source for space-based laser ranging are outlined, and some of the recent developments in the laser field most relevant to space-based lasers for ranging and altimetry are surveyed. Laser pulse width and laser design are discussed. It is argued that, while doubled/tripled ND-host lasers are currently the best choice for laser ranging in two colors, they have the shortcoming that the atmospheric transmission at 355 nm is significantly poorer than it is at longer wavelengths which still have sufficient dispersion for two-color laser ranging. The life requirement appears to demand that laser diode pumping be used for space applications.

  1. Two-color femtosecond experiments by use of two independently tunable Ti:sapphire lasers with a sample-and-hold switch.

    Science.gov (United States)

    Sohn, J Y; Ahn, Y H; Yee, K J; Kim, D S

    1999-09-20

    We performed femtosecond two-color experiments (four-wave mixing and pump probe) using two independently tunable, partially synchronized femtosecond lasers. Despite the fact that the jitter is of the order of 5-10 ps, the time resolution is limited only by the pulse width when a homemade sample-and-hold switch is used.

  2. Laser Range Sensors

    Directory of Open Access Journals (Sweden)

    K.C. Bahuguna

    2007-11-01

    Full Text Available This paper presents the design aspects of laser range finders and proximity sensors being developed at IRDE for different applications. The principle used in most of the laser range finders is pulse echo or time-of-flight measurement. Optical triangulation is used in proximity sensors while techniques like phase detection and interferometry are employed in instruments for surveying and motion controllers where high accuracy is desired. Most of the laser range finders are designed for ranging non-cooperative targets.

  3. The effect of frequency chirping on electron-positron pair production in the one- and two-color laser pulse fields

    CERN Document Server

    Abdukerim, Nuriman; Xie, Bai-Song

    2016-01-01

    The effect of the frequency chirping on momentum spectrum and pair production rate in one- and two-color laser pulse fields is investigated by solving the quantum Vlasov equation. A small frequency chirp shifts the momentum spectrum along the momentum axis. The positive and negative frequency chirp parameters play the same role in increasing the pair number density. The sign change of frequency chirp parameter at the moment $t=0$ leads pulse shape and momentum spectrum to be symmetric, and the number density to be increased. The number density of produced pairs in the two-color pulse field is much higher than that in the one-color pulse field and the larger frequency chirp pulse field dominates more strongly. In the two-color pulse fields, the relation between the frequency ratio of two colors and the number density is not sensitive to the parameters of small frequency chirp added in either low frequency strong field or high frequency weak field but sensitive to the parameters of large frequency chirp added i...

  4. Two-color above threshold ionization of atoms and ions in XUV Bessel beams and combined with intense laser light

    CERN Document Server

    Seipt, D; Surzhykov, A; Fritzsche, S

    2016-01-01

    The two-color above-threshold ionization (ATI) of atoms and ions is investigated for a vortex Bessel beam in the presence of a strong near-infrared (NIR) light field. While the photoionization is caused by the photons from the weak but extreme ultra-violet (XUV) vortex Bessel beam, the energy and angular distribution of the photoelectrons and their sideband structure are affected by the plane-wave NIR field. We here explore the energy spectra and angular emission of the photoelectrons in such two-color fields as a function of the size and location of the target (atoms) with regard to the beam axis. In addition, analogue to the circular dichroism in typical two-color ATI experiments with circularly polarized light, we define and discuss seven different dichroism signals for such vortex Bessel beams that arise from the various combinations of the orbital and spin angular momenta of the two light fields. For localized targets, it is found that these dichroism signals strongly depend on the size and position of t...

  5. Silicon isotope separation utilizing infrared multiphoton dissociation of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser light

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Atsushi; Ohba, Hironori; Hashimoto, Masashi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishii, Takeshi; Ohya, Akio [Nuclear Development Corp., Tokai, Ibaraki (Japan); Arai, Shigeyoshi [Hill Research Co. Ltd., Tokyo (Japan)

    2002-08-01

    Silicon isotope separation has been done by utilizing the Infrared Multiphoton Dissociation (IRMPD) of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser lights. The two-color excitation method improved the separation efficiency keeping the high enrichment factors. For example, 99.74% of {sup 28}Si was obtained at 49.63% dissociation of Si{sub 2}F{sub 6} after the simultaneous irradiation of 200 pulses with 966.23 cm{sup -1} photons (0.084 J/cm{sup 2}) and 954.55 cm{sup -1} photons (0.658 J/cm{sup 2}), while 2000 pulses were needed to obtain 99.35% of {sup 28}Si at 35.6% dissociation in the case of only one-color irradiation at 954.55 cm{sup -1} (0.97 J/cm{sup 2}). (author)

  6. The spatial distribution in high-order harmonic generation of H2+ with different time delays of the two-color laser fields

    Science.gov (United States)

    Zhang, Jun; Pan, Xue-Fei; Du, Hui; Xu, Tong-Tong; Guo, Jing; Liu, Xue-Shen

    2017-01-01

    We theoretically investigate the high-order harmonic generation (HHG) and the spatial distribution in HHG of the H2+ molecule by introducing a time-delayed two-color laser field which consists of the mid-infrared and near-infrared laser field. For the different time delays of the two-color laser fields, the pulse shapes are changed which result in the variation of the electron recombined with the nuclei along the positive- or negative-z direction. When the time delay is 0 fs (1.34 fs), a smooth harmonic plateau from the electron recombined with the nuclei along the negative (positive)-z direction can be achieved. An isolated attosecond pulse with a duration of about 99 as is generated when the time delay is 1.34 fs. We perform the classical analysis which is consistent with the numerical results from the one-dimensional non-Born-Oppenheimer time dependent Schrödinger equation (TDSE). We also investigate emission time of harmonics in terms of a time-frequency analysis to further understand the underlying physical mechanism.

  7. Reconfigurable laser ranging instrument

    Science.gov (United States)

    Schneiter, John

    1994-03-01

    This paper describes the design and operation of a fast, flexible, non-contact, eye-safe laser ranging instrument useful in a variety of industrial metrology situations, such as in-process machining control and part inspection. The system has variable computer-controlled standoff and depth of field, and can obtain 3-D images of surfaces within a range of from 1.5 ft to almost 10 ft from the final optical element. The minimum depth of field is about 3.5 in. at 1.5 ft and about 26 in. at the far range. The largest depth of field for which useful data are available is about 41 in. Resolution, with appropriate averaging, is about one part in 4000 of the depth of field, which implies a best case resolution for this prototype of 0.00075 in. System flexibility is achieved by computer controlled relative positioning of optical components.

  8. Terahertz Emission Dependence on the Fundamental Optical Intensity in Generating Terahertz Waves from Two-Color Laser-Induced Gas Plasma

    Institute of Scientific and Technical Information of China (English)

    DAI Hou-Mei; LIU Jin-Song

    2011-01-01

    A transient photocurrent model is used to explain terahertz ermission from gas plasma irritated by two-color laser pulses,with one the second harmonic of the other.Taking multiple degrees of ionization into account,the gas ionization process at different laser intensities from 1014 W/cm2 to 1015 W/cm2 is discussed.The results show that when Iω ≥ 6 × 1014 W/cm2,double ionization plays an important role in producing electrons.The corresponding terahertz spectra and waveforms are calculated,showing that increasing laser intensity can broaden the spectra to high frequencies and enhance the terahertz field.A promising method for generating terahertz (THz) waves involves emission from laser induced gas plasmas,which was first introduced hy Hamster et al.[1,2] By focusing laser femtosecond pulses with intensity greater than the thresholl for ionization of the gas molecules,one can obtain significant plasma formation.The ionized electrons will then accelerate by the lapser ponderomotive force,thus an electromagnetic pulse at THz frcqucncies can be produced.Since then,other plasma-based THz generation scheines have been proposed.L(o)ffler et al.,[3,4] applied an external dc bias to the plasma region,leading to an approximately one order of magnitude increase in the THz field strength.%A transient photocurrent model is used to explain terahertz emission from gas plasma irritated by two-color laser pulses, with one the second harmonic of the other. Taking multiple degrees of iom'xntion into account, the gas ionizntion process at different laser intensities from 1014 W/cm2 to 1015 W/cm2 is discussed. The results show that when /w > 6 X 1014 W/cin2, double ionization plays an important role in producing electrons. The corresponding terahertz spectra and waveforms are calculated, showing that increasing laser intensity can broaden the spectra to high frequencies and enhance the terahertz Geld.

  9. Demonstration of Single-Crystal Self-Seeded Two-Color X-Ray Free-Electron Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Lutman, A. A.; Decker, F. -J; Arthur, J.; Chollet, M.; Feng, Y.; Hastings, J.; Huang, Z.; Lemke, H.; Nuhn, H. -D.; Marinelli, A.; Turner, J. L.; Wakatsuki, S.; Welch, J.; Zhu, D.

    2014-12-18

    A scheme for generating two simultaneous hard-x-ray free-electron laser pulses with a controllable difference in photon energy is described and then demonstrated using the self-seeding setup at the Linac Coherent Light Source (LCLS). The scheme takes advantage of the existing LCLS equipment, which allows two independent rotations of the self-seeding diamond crystal. The two degrees of freedom are used to select two nearby crystal reflections, causing two wavelengths to be present in the forward transmitted seeding x-ray pulse. The free-electron laser system must support amplification at both desired wavelengths.

  10. Absolute phase control of spectra effects in a two-level medium driven by two-color ultrashort laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Xia Keyu [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate University of Chinese Academy of Sciences (China); Niu Yueping [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate University of Chinese Academy of Sciences (China); Li Chunfang [Department of Physics, Shanghai University, Shanghai 200436 (China); Gong Shangqing [CCAST (World Laboratory), PO Box 8730, Beijing 100080 (China) and State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)]. E-mail: sqgong@siom.ac.cn

    2007-01-22

    Using a {omega}-3{omega} combination scenario, we investigate the absolute phase control of the spectra effects for ultrashort laser pulses propagating in a two-level medium. It is found that the higher spectral components can be controlled by the absolute phases. In particular, different absolute phase combinations can lead to the buildup or split of the even harmonics.

  11. Coherent control of optical four-wave mixing by two-color $\\omega$-$3\\omega$ ultrashort laser pulses

    CERN Document Server

    Serrat, C

    2004-01-01

    A theoretical investigation on the phase control of optical transient four-wave mixing interactions in two-level systems driven by two intense temporal coherent femtosecond laser pulses of central angular frequencies $\\omega$ and $3\\omega$ is reported. By solving the full Maxwell-Bloch equations beyond the slowly-varying envelope and rotating-wave approximations in the time domain, the parametric nonlinear coupling to the optical field at frequency $5\\omega$ is found to depend critically on the initial relative phase $\\phi$ of the two propagating pulses; the coupling is enhanced when the pulses interfere constructively in the center ($\\phi=0$), while it is nearly suppressed when they are out of phase ($\\phi=\\pi$).

  12. Intensity Correlation Function of a Single-Mode Laser Driven by Two Colored Noises with Colored Cross-Correlation

    Institute of Scientific and Technical Information of China (English)

    HANLi-Bo; CAOLi; WUDa-Jin; WANGJun

    2004-01-01

    By using the linear approximation method, the intensity correlation function and the intensity correlation time are calculated in a gain-noise model of a single-mode laser driven by colored cross-correlated pump noise and quantum noise, each of which is colored. We detect that, when the cross-correlation between both noises is negative, the behavior of the intensity correlation function C(t) versus time t, in addition to decreasing monotonously, also exhibits several other cases, such as one maximum, one minimum, and two extrema (one maximum and one minimum), i.e., some parameters of the noises can greatly change the dependence of the intensity correlation function upon time. Moreover, we find that there is a minimum Tmin in the curve of the intensity correlation time versus the pump noise intensity, and the depth and position of Train strongly depend on the quantum noise self-correlation time T2 and cross-correlation time T3.

  13. Two-color facility based on a broadly tunable infrared free-electron laser and a subpicosecond-synchronized 10-fs-Ti : Sapphire laser

    NARCIS (Netherlands)

    Knippels, G.M.H.; van de Pol, M.J.; Pellemans, H. P. M.; Planken, P. C. M.; van der Meer, A. F. G.

    1998-01-01

    Subpicosecond synchronization between a mirror-dispersion-controlled 10-fs Ti:sapphire laser and the Free-Electron Laser for Infrared Experiments has been achieved. The measured intensity cross correlation between the two lasers is consistent with a jitter of only 400 fs rms. The wide and continuous

  14. Laser radiation frequency conversion in carbon- and cluster-containing plasma plumes under conditions of single and two-color pumping by pulses with a 10-Hz repetition rate

    Science.gov (United States)

    Ganeev, R. A.

    2013-07-01

    This work reviews a series of investigations of different plasma plumes using single- and two-color laser systems that emit femtosecond pulses with a 10-Hz repetition rate. Results of investigation of the resonant enhancement of harmonics in tin plasma with the use of two types of pumps are analyzed, and it is shown that the tuning of the wavelengths of harmonics to ion-resonance levels plays an important role in increasing the conversion efficiency to high-order harmonics of the radiation to be converted. Investigations of different carbon-containing plasma media (carbon nanotubes, graphite, carbon aerogel, etc.) exhibit attractive properties of the nonlinear medium of this type for efficient generation of high-order harmonics. The results of the first experiments on the use of nanoparticles produced directly in the course of laser ablation of metals for increasing the efficiency of harmonics generated in this cluster-containing medium are analyzed. It is shown that new approaches realized in these investigations give hope that the nonlinear optical response of plasma media in the far-ultraviolet range can be further increased.

  15. Mobile Lunar Laser Ranging Station

    Science.gov (United States)

    Intellect, 1977

    1977-01-01

    Harlan Smith, chairman of the University of Texas's Astronomy Department, discusses a mobile lunar laser ranging station which could help determine the exact rates of movement between continents and help geophysicists understand earthquakes. He also discusses its application for studying fundamental concepts of cosmology and physics. (Editor/RK)

  16. Dynamics of the formation of laser-induced periodic surface structures (LIPSS) upon femtosecond two-color double-pulse irradiation of metals, semiconductors, and dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Höhm, S.; Herzlieb, M.; Rosenfeld, A. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Krüger, J. [BAM Bundesanstalt für Materialforschung und –prüfung, Unter den Eichen 87, D-12205 Berlin (Germany); Bonse, J., E-mail: joern.bonse@bam.de [BAM Bundesanstalt für Materialforschung und –prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)

    2016-06-30

    Graphical abstract: - Highlights: • LIPSS formation on Fused Silica, Silicon, and Titanium is studied upon parallel and cross-polarized two-color (400 and 800 nm) double-fs-pulse irradiation. • LIPSS orientation on Fused Silica follows the polarization of the first pulse. • LIPSS formation on Silicon and Titanium can be explained by a plasmonic model. - Abstract: In order to address the dynamics and physical mechanisms of LIPSS formation for three different classes of materials (metals, semiconductors, and dielectrics), two-color double-fs-pulse experiments were performed on Titanium, Silicon and Fused Silica. For that purpose a Mach–Zehnder interferometer generated polarization controlled (parallel or cross-polarized) double-pulse sequences at 400 nm and 800 nm wavelength, with inter-pulse delays up to a few picoseconds. Multiple of these two-color double-pulse sequences were collinearly focused by a spherical mirror to the sample surfaces. The fluence of each individual pulse (400 nm and 800 nm) was always kept below its respective ablation threshold and only the joint action of both pulses lead to the formation of LIPSS. Their resulting characteristics (periods, areas) were analyzed by scanning electron microscopy. The periods along with the LIPSS orientation allow a clear identification of the pulse which dominates the energy coupling to the material. For strong absorbing materials (Silicon, Titanium), a wavelength-dependent plasmonic mechanism can explain the delay-dependence of the LIPSS. In contrast, for dielectrics (Fused Silica) the first pulse always dominates the energy deposition and LIPSS orientation, supporting a non-plasmonic formation scenario. For all materials, these two-color experiments confirm the importance of the ultrafast energy deposition stage for LIPSS formation.

  17. Dynamics of the formation of laser-induced periodic surface structures (LIPSS) upon femtosecond two-color double-pulse irradiation of metals, semiconductors, and dielectrics

    Science.gov (United States)

    Höhm, S.; Herzlieb, M.; Rosenfeld, A.; Krüger, J.; Bonse, J.

    2016-06-01

    In order to address the dynamics and physical mechanisms of LIPSS formation for three different classes of materials (metals, semiconductors, and dielectrics), two-color double-fs-pulse experiments were performed on Titanium, Silicon and Fused Silica. For that purpose a Mach-Zehnder interferometer generated polarization controlled (parallel or cross-polarized) double-pulse sequences at 400 nm and 800 nm wavelength, with inter-pulse delays up to a few picoseconds. Multiple of these two-color double-pulse sequences were collinearly focused by a spherical mirror to the sample surfaces. The fluence of each individual pulse (400 nm and 800 nm) was always kept below its respective ablation threshold and only the joint action of both pulses lead to the formation of LIPSS. Their resulting characteristics (periods, areas) were analyzed by scanning electron microscopy. The periods along with the LIPSS orientation allow a clear identification of the pulse which dominates the energy coupling to the material. For strong absorbing materials (Silicon, Titanium), a wavelength-dependent plasmonic mechanism can explain the delay-dependence of the LIPSS. In contrast, for dielectrics (Fused Silica) the first pulse always dominates the energy deposition and LIPSS orientation, supporting a non-plasmonic formation scenario. For all materials, these two-color experiments confirm the importance of the ultrafast energy deposition stage for LIPSS formation.

  18. Laser ranging ground station development

    Science.gov (United States)

    Faller, J. E.

    1973-01-01

    The employment of ground to conduct radar range measurements of the lunar distance is discussed. The advantages of additional ground stations for this purpose are analyzed. The goals which are desirable for any new type of ranging station are: (1) full time availability of the station for laser ranging, (2) optimization for signal strength, (3) automation to the greatest extent possible, (4) the capability for blind pointing, (5) reasonable initial and modest operational costs, and (6) transportability to enhance the value of the station for geophysical purposes.

  19. Nonvolatile two-color holographic recording in near-stoichiometric lithium niobate crystals gated by incoherent ultraviolet light

    Institute of Scientific and Technical Information of China (English)

    Shaolin Chen; Xiangming Liu; Bo Fu; Guoquan Zhang

    2009-01-01

    Nonvolatile two-color holographic recording gated by incoherent ultraviolet (UV) light centered at 365 nm is investigated in near-stoichiometric lithium niobate crystals. The influence of thermal treatment on the two-color recording is studied. The results show that thermal reduction tends to improve the two-color recording performance, whereas thermal oxidation degrades the two-color recording. With an incoherent 0.2-W/cm2 UV gating light and a 0.25-W/cm2 semiconductor recording laser at 780 nm, a two-color recording sensitivity of 4 x 10-3 cm/J and a recording dynamic range characterized by M/# of 0.12 are achieved in a 2.2-mm thermally reduced near-stoichiometric lithium niobate crystal. We attribute the improvement to the prolonged lifetime of small polarons and the increased absorption at the gating wavelength due to thermal reduction.

  20. Ultra-low emittance beam generation using two-color ionization injection in a CO2 laser-driven plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Carl [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Benedetti, Carlo [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bulanov, Stepan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chen, Min [Shanghai Jiao Tong Univ. (China); Esarey, Eric [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Geddes, Cameron [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Vay, J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yu, Lule [Shanghai Jiao Tong Univ. (China); Leemans, Wim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-05-21

    Ultra-low emittance (tens of nm) beams can be generated in a plasma accelerator using ionization injection of electrons into a wakefield. An all-optical method of beam generation uses two laser pulses of different colors. A long-wavelength drive laser pulse (with a large ponderomotive force and small peak electric field) is used to excite a large wakefield without fully ionizing a gas, and a short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the pump laser, to ionize a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wake. The trapping condition, the ionized electron distribution, and the trapped bunch dynamics are discussed. Expressions for the beam transverse emittance, parallel and orthogonal to the ionization laser polarization, are presented. An example is shown using a 10-micron CO2 laser to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection.

  1. Ultra-low emittance beam generation using two-color ionization injection in a CO2 laser-driven plasma accelerator

    CERN Document Server

    Schroeder, C B; Bulanov, S S; Chen, M; Esarey, E; Geddes, C G R; Vay, J -L; Yu, L -L; Leemans, W P

    2015-01-01

    Ultra-low emittance (tens of nm) beams can be generated in a plasma accelerator using ionization injection of electrons into a wakefield. An all-optical method of beam generation uses two laser pulses of different colors. A long-wavelength drive laser pulse (with a large ponderomotive force and small peak electric field) is used to excite a large wakefield without fully ionizing a gas, and a short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the pump laser, to ionize a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wake. The trapping condition, the ionized electron distribution, and the trapped bunch dynamics are discussed. Expressions for the beam transverse emittance, parallel and orthogonal to the ionization laser polarization, are presented. An example is shown using a 10-micron CO2 laser to drive the wake and a frequency-doubled Ti:Al2...

  2. Two-color laser-induced incandescence and cavity ring-down spectroscopy for sensitive and quantitative imaging of soot and PAHs in flames

    Science.gov (United States)

    Schoemaecker Moreau, C.; Therssen, E.; Mercier, X.; Pauwels, J. F.; Desgroux, P.

    Laser-induced incandescence is a technique which enables the measurement of soot volume fractions. However, the laser-induced soot emission might be affected by a fluorescence background generally ascribed to the polycyclic aromatic hydrocarbon compounds (PAHs) present at the soot location. In this paper, spatially resolved distributions of PAH absorbance and soot are obtained in sooting diffusion flames. The original method developed here consists in comparing the emission distributions induced by two different laser wavelengths: (1) at 1064 nm emission signals are exempt from PAH fluorescence and (2) at 532 nm both soot incandescence and PAH emission contribute to the total signal. In addition, the absolute absorption coefficient of the PAH mixture is determined by comparing absorption measurements obtained by cavity ring-down spectroscopy (CRDS) at 1064 nm and 532 nm. The proposed method can provide highly sensitive 2D imaging of PAHs and soot using the fundamental and the second-harmonic frequencies of a single YAG laser. Finally, 2D distributions of PAH absorbance and soot volume fraction calibrated by CRDS are obtained in two diffusion flames, particularly in a very low-sooting flame exhibiting a maximum PAH absorbance of 6×10-4 cm-1 and a maximum soot volume fraction of 3 ppb only. The respective spatial distributions of PAHs and soot are shown to vary with the initial C/O ratio.

  3. Theoretical analysis and numerical solution of laser pulse transformation for satellite laser ranging

    Institute of Scientific and Technical Information of China (English)

    FAN; Jianxing

    2001-01-01

    [1]Yang Fumin,Xiao Chikun,Chen Wanzhen et al.,Design and observations of satellite laser ranging system for daylight tracking at Shanghai Observatory,Science in China,Series A,1999,42(2):198-206.[2]Degnan,J.,Effects of detection threshold and signal strength on lageos range bias,Proceedings of Ninth International Workshop on Laser Ranging Instrumentation,1994,3:920-925.[3]Degnan,J.,Satellite laser ranging:current status and future prospects,IEEE Transactions on Geoscience and Remote Sensing,1985,GE-23(4):398-413.[4]Degnan,J.,Millimeter accuracy satellites for two color ranging,Proceedings of Eighth International Workshop on Laser Ranging Instrumentation,1992,7:36-51.[5]Neubert,R.,An analytical model of satellite signature effects,Proceedings of Ninth International Workshop on Laser Ranging Instrumentation,1994,1:82-91.[6]Si Yu,Li Yaowu,Application of Probability and Math-Physics Statistics (in Chinese),Xi'an:Xi'an Jiaotong University Press,1997,48-49.[7]Li Huxi,Jiang Hong,Matlab Step by Step[M](in Chinese),Shanghai:Shanghai Jiaotong University Press,1997,91-93[8]Si Suo,Mathcad 7.0 Practice Course (in Chinese),Beijing:The People's Post & Communication Press,1998,126-127.[9]Xi Meicheng,Methods of Numerical Analysis (in Chinese),Hefei:University of Science and Technology of China Press,1995,123-134.[10]Fan Jianxing,Yang Fumin,Chen Qixiu,The CoM model of satellite signature for laser ranging,Acta Photonica Sinica (in Chinese),2000,29(11):1012-1016.[11]Lu Dajin,Random Process & Its Application (in Chinese),Beijing:Tsinghua University Press,1986,133-137.

  4. Two-color infrared detector

    Science.gov (United States)

    Klem, John F; Kim, Jin K

    2014-05-13

    A two-color detector includes a first absorber layer. The first absorber layer exhibits a first valence band energy characterized by a first valence band energy function. A barrier layer adjoins the first absorber layer at a first interface. The barrier layer exhibits a second valence band energy characterized by a second valence band energy function. The barrier layer also adjoins a second absorber layer at a second interface. The second absorber layer exhibits a third valence band energy characterized by a third valence band energy function. The first and second valence band energy functions are substantially functionally or physically continuous at the first interface and the second and third valence band energy functions are substantially functionally or physically continuous at the second interface.

  5. Two-color beam generation based on wakefield excitation

    Science.gov (United States)

    Bettoni, S.; Prat, E.; Reiche, S.

    2016-05-01

    Several beam manipulation methods have been studied and experimentally tested to generate two-color photon beams in free electron laser facilities to accommodate the user requests. We propose to use the interaction of the beam with an oscillating longitudinal wakefield source to obtain a suitable electron beam structure. The bunch generates two subpulses with different energies and delayed in time passing through a magnetic chicane after its longitudinal phase space has been modulated by the wakefield source. According to this approach the power of the emitted radiation is not degraded compared to the monochromatic beam, and the setup in the machine is quite simple because the bunch is manipulated only in the high energy section, where it is more rigid. We present the design applied to SwissFEL. We identified the parameters and the corresponding range of tunability of the time and energy separation among the two subbunches.

  6. Rational choices for the wavelengths of a two color interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Jobes, F.C.

    1995-07-01

    If in a two color interferometer for plasma density measurements, the two wavelengths are chosen to have a ratio that is a rational number, and if the signals from each of the wavelengths are multiplied in frequency by the appropriate integer of the rational number and then heterodyned together, the resultant signal will have all effects of component motion nulled out. A phase measurement of this signal will have only plasma density information in it. With CO{sub 2} lasers, it is possible to find suitable wavelength pairs which are close enough to rational numbers to produce an improvement of about 100 in density resolution, compared to standard two color interferometers.

  7. Ranging performance of active laser detection

    Science.gov (United States)

    Sun, Huayan; Xiong, Fei; Gu, Suolin

    2006-06-01

    Ranging performance is described for photoelectric equipment reconnaissance using an active laser detection system that is based on the 'cat's eyes' effect of optical windows. Active laser detection systems have an advantage over passive systems because they can measure target velocity and spatial coordinates. However, there are several challenging problems here because of the great distances involved, the low returned power of the uncooperative target, and the optical aberrations induced by the atmosphere. In the design of this system, the principle of detection is based on the 'cat's eyes' effect according to which the optical windows of photoelectric equipments have a strong reflect character towards incident laser beam. With 'cat's eyes' effect, the detection of uncooperative target can be translated into one of a cooperative target, so the ratio of returned laser can be increased. In this paper, the ranging performance presented here takes into account all the various elements of the system, from the laser emission, target, atmospheric propagation to the detector. The characteristics of back-reflected laser and an estimate of the laser Cross Section (LCS) from 'cat's eyes target' are investigated in theory and simulation. The Signal-to-Noise Ratio (SNR) is calculated by combining the probability of detection of the system for given electronic characteristics of the system and for a given probability of false alarms. On the basis of analysis of SNR, minimum detectable signal power, operating distance of the system and factors affecting the ranging performance is analyzed. Results indicate that system has characters of long range, and high sensitivity. It can be used to detect the aerial targets such as reconnaissance drone, navigate missile, reconnaissance satellite etc.

  8. Long-range laser-illuminated imaging

    Science.gov (United States)

    Dayton, David C.; Browne, Stephen L.; Sandven, Steven C.; Gonglewski, John D.; Gallegos, Joe; Shilko, Michael L., Sr.

    2000-11-01

    We demonstrate the utility of laser illuminated imaging for clandestine night time surveillance from a simulated airborne platform at standoff ranges in excess 20 km. In order to reduce the necessary laser per pulse energy required for illumination at such long ranges, and to mitigate atmospheric turbulence effects on image resolution, we have investigated a unique multi-frame post-processing technique. It is shown that in the presence of atmospheric turbulence and coherent speckle effects, this approach can produce superior results to conventional scene flood illumination.

  9. Tests of Gravity Using Lunar Laser Ranging

    Directory of Open Access Journals (Sweden)

    Stephen M. Merkowitz

    2010-11-01

    Full Text Available Lunar laser ranging (LLR has been a workhorse for testing general relativity over the past four decades. The three retroreflector arrays put on the Moon by the Apollo astronauts and the French built arrays on the Soviet Lunokhod rovers continue to be useful targets, and have provided the most stringent tests of the Strong Equivalence Principle and the time variation of Newton’s gravitational constant. The relatively new ranging system at the Apache Point 3.5 meter telescope now routinely makes millimeter level range measurements. Incredibly, it has taken 40 years for ground station technology to advance to the point where characteristics of the lunar retroreflectors are limiting the precision of the range measurements. In this article, we review the gravitational science and technology of lunar laser ranging and discuss prospects for the future.

  10. Two-color QCD at high density

    Energy Technology Data Exchange (ETDEWEB)

    Boz, Tamer; Skullerud, Jon-Ivar [Department of Mathematical Physics, Maynooth University, Maynooth, Co. Kildare (Ireland); Centre for the Subatomic Structure of Matter, Adelaide University, Adelaide, SA 5005 (Australia); Giudice, Pietro [Universität Münster, Institut für Theoretische Physik, Münster (Germany); Hands, Simon [Department of Physics, College of Science, Swansea University, Swansea (United Kingdom); Williams, Anthony G. [Centre for the Subatomic Structure of Matter, Adelaide University, Adelaide, SA 5005 (Australia)

    2016-01-22

    QCD at high chemical potential has interesting properties such as deconfinement of quarks. Two-color QCD, which enables numerical simulations on the lattice, constitutes a laboratory to study QCD at high chemical potential. Among the interesting properties of two-color QCD at high density is the diquark condensation, for which we present recent results obtained on a finer lattice compared to previous studies. The quark propagator in two-color QCD at non-zero chemical potential is referred to as the Gor’kov propagator. We express the Gor’kov propagator in terms of form factors and present recent lattice simulation results.

  11. In situ spatial mapping of Gouy phase slip with terahertz generation in two-color field.

    Science.gov (United States)

    Meng, Chao; Lü, Zhihui; Huang, Yindong; Wang, Xiaowei; Chen, Wenbo; Zhang, Dongwen; Zhao, Zengxiu; Yuan, Jianmin

    2016-05-30

    We establish a one-to-one mapping between the local phase slip and the spatial position near the focus by scanning a thin jet along the propagation direction of laser beams. The measurement shows that the optimal phase of terahertz can be utilized to characterize in situ the spatially dependent relative phase of the two-color field. We also investigate the role of the Gouy phase shift on terahertz generation from two-color laser-induced plasma. The result is of critical importance for phase-dependent applications of two-color laser-field, including high-order harmonic and terahertz generation.

  12. Satellite and lunar laser ranging in infrared

    Science.gov (United States)

    Courde, Clement; Torre, Jean-Marie; Samain, Etienne; Martinot-Lagarde, Gregoire; Aimar, Mourad; Albanese, Dominique; Maurice, Nicolas; Mariey, Hervé; Viot, Hervé; Exertier, Pierre; Fienga, Agnes; Viswanathan, Vishnu

    2017-05-01

    We report on the implementation of a new infrared detection at the Grasse lunar laser ranging station and describe how infrared telemetry improves the situation. We present our first results on the lunar reflectors and show that infrared detection permits us to densify the observations and allows measurements during the new and the full moon periods. We also present the benefit obtained on the ranging of Global Navigation Satellite System (GNSS) satellites and on RadioAstron which have a very elliptic orbit.

  13. Clock comparison based on laser ranging technologies

    Science.gov (United States)

    Samain, Etienne

    2015-06-01

    Recent progress in the domain of time and frequency standards has required some important improvements of existing time transfer links. Several time transfer by laser link (T2L2) projects have been carried out since 1972 with numerous scientific or technological objectives. There are two projects currently under exploitation: T2L2 and Lunar Reconnaissance Orbiter (LRO). The former is a dedicated two-way time transfer experiment embedded on the satellite Jason-2 allowing for the synchronization of remote clocks with an uncertainty of 100 ps and the latter is a one-way link devoted for ranging a spacecraft orbiting around the Moon. There is also the Laser Time Transfer (LTT) project, exploited until 2012 and designed in the frame of the Chinese navigation constellation. In the context of future space missions for fundamental physics, solar system science or navigation, laser links are of prime importance and many missions based on that technology have been proposed for these purposes.

  14. Multi-target compressive laser ranging

    Science.gov (United States)

    Pandit, Pushkar P.; Dahl, Jason R.; Barber, Zeb W.; Babbitt, W. Randall

    2014-05-01

    Compressive laser ranging (CLR) is a method that exploits the sparsity available in the range domain using compressive sensing methods to directly obtain range domain information. Conventional ranging methods are marred by requirements of high bandwidth analog detection which includes severe SNR fall off with bandwidth in analog-to-digital conversion (ADC). Compressive laser ranging solves this problem by obtaining sub-centimeter resolution while using low bandwidth detection. High rate digital pulse pattern generators and off the shelf photonic devices are used to modulate the transmitted and received light from a superluminescent diode. CLR detection is demonstrated using low bandwidth, high dynamic range detectors along with photon counting techniques. The use of an incoherent source eliminates speckle issues and enables simplified CLR methods to get multi-target range profiles with 1-3cm resolution. Using compressive sensing methods CLR allows direct range measurements in the sub-Nyquist regime while reducing system resources, in particular the need for high bandwidth ADC.

  15. Lunar laser ranging in infrared at the Grasse laser station

    Science.gov (United States)

    Courde, C.; Torre, J. M.; Samain, E.; Martinot-Lagarde, G.; Aimar, M.; Albanese, D.; Exertier, P.; Fienga, A.; Mariey, H.; Metris, G.; Viot, H.; Viswanathan, V.

    2017-06-01

    For many years, lunar laser ranging (LLR) observations using a green wavelength have suffered an inhomogeneity problem both temporally and spatially. This paper reports on the implementation of a new infrared detection at the Grasse LLR station and describes how infrared telemetry improves this situation. Our first results show that infrared detection permits us to densify the observations and allows measurements during the new and the full Moon periods. The link budget improvement leads to homogeneous telemetric measurements on each lunar retro-reflector. Finally, a surprising result is obtained on the Lunokhod 2 array which attains the same efficiency as Lunokhod 1 with an infrared laser link, although those two targets exhibit a differential efficiency of six with a green laser link.

  16. Matera Laser Ranging Observatory (MLRO): An overview

    Science.gov (United States)

    Varghese, Thomas K.; Decker, Winfield M.; Crooks, Henry A.; Bianco, Giuseppe

    1993-01-01

    The Agenzia Spaziale Italiana (ASI) is currently under negotiation with the Bendix Field Engineering Corporation (BFEC) of the Allied Signal Aerospace Company (ASAC) to build a state-of-the-art laser ranging observatory for the Centro di Geodesia Spaziale, in Matera, Italy. The contract calls for the delivery of a system based on a 1.5 meter afocal Cassegrain astronomical quality telescope with multiple ports to support a variety of experiments for the future, with primary emphasis on laser ranging. Three focal planes, viz. Cassegrain, Coude, and Nasmyth will be available for these experiments. The open telescope system will be protected from dust and turbulence using a specialized dome which will be part of the building facilities to be provided by ASI. The fixed observatory facility will be partitioned into four areas for locating the following: laser, transmit/receive optics, telescope/dome enclosure, and the operations console. The optical tables and mount rest on a common concrete pad for added mechanical stability. Provisions will be in place for minimizing the effects of EMI, for obtaining maximum cleanliness for high power laser and transmit optics, and for providing an ergonomic environment fitting to a state-of-the-art multipurpose laboratory. The system is currently designed to be highly modular and adaptable for scaling or changes in technology. It is conceived to be a highly automated system with superior performance specifications to any currently operational system. Provisions are also made to adapt and accommodate changes that are of significance during the course of design and integration.

  17. Lunar laser ranging: the millimeter challenge

    CERN Document Server

    Murphy, T W

    2013-01-01

    Lunar laser ranging has provided many of the best tests of gravitation since the first Apollo astronauts landed on the Moon. The march to higher precision continues to this day, now entering the millimeter regime, and promising continued improvement in scientific results. This review introduces key aspects of the technique, details the motivations, observables, and results for a variety of science objectives, summarizes the current state of the art, highlights new developments in the field, describes the modeling challenges, and looks to the future of the enterprise.

  18. Satellite Laser Ranging and General Relativity

    CERN Document Server

    Iorio, L

    2001-01-01

    In this work some aspects of the detection of certain general relativistic effects in the weak gravitational field of the Earth via laser-ranged data to some existing or proposed geodetic satellites are examined. The focus is on the Lense-Thirring drag of the orbit of a test body, the gravitomagnetic clock effect and the gravitoelectric perigee shift. The impact of some sources of systematic errors is investigated. An experiment whose goal is the measurement of the PPN parameters beta and gamma in the terrestrial field with LAGEOS satellites at a level of 10^(-3)is presented. A modified version of the proposed LARES mission is examined.

  19. Improved pulse laser ranging algorithm based on high speed sampling

    Science.gov (United States)

    Gao, Xuan-yi; Qian, Rui-hai; Zhang, Yan-mei; Li, Huan; Guo, Hai-chao; He, Shi-jie; Guo, Xiao-kang

    2016-10-01

    Narrow pulse laser ranging achieves long-range target detection using laser pulse with low divergent beams. Pulse laser ranging is widely used in military, industrial, civil, engineering and transportation field. In this paper, an improved narrow pulse laser ranging algorithm is studied based on the high speed sampling. Firstly, theoretical simulation models have been built and analyzed including the laser emission and pulse laser ranging algorithm. An improved pulse ranging algorithm is developed. This new algorithm combines the matched filter algorithm and the constant fraction discrimination (CFD) algorithm. After the algorithm simulation, a laser ranging hardware system is set up to implement the improved algorithm. The laser ranging hardware system includes a laser diode, a laser detector and a high sample rate data logging circuit. Subsequently, using Verilog HDL language, the improved algorithm is implemented in the FPGA chip based on fusion of the matched filter algorithm and the CFD algorithm. Finally, the laser ranging experiment is carried out to test the improved algorithm ranging performance comparing to the matched filter algorithm and the CFD algorithm using the laser ranging hardware system. The test analysis result demonstrates that the laser ranging hardware system realized the high speed processing and high speed sampling data transmission. The algorithm analysis result presents that the improved algorithm achieves 0.3m distance ranging precision. The improved algorithm analysis result meets the expected effect, which is consistent with the theoretical simulation.

  20. Development of a two-color FQI

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, T.; Wei, G. [Brookhaven National Lab., Upton, NY (United States)

    1996-07-01

    The Flame Quality Indicator (FQI) concept was developed at Brookhaven National Laboratory as a simple device which could be used to monitor oil burner flames and indicate when a problem was starting to occur. Fault situations which could be identified by the FQI include: fouled nozzle, increased or decreased excess air, blocked air inlet or flue, and use of low quality oil. The basic concept of the FQI is quite simple. A conventional cadmium sulfide photocell is used to measure the amount of light emitted from an oil burner flame when the appliance is fully warmed-up. The measured amount of light is compared to a set point, established during burner tune-up. If the two intensities differ by more than a set range, a {open_quotes}service required{close_quotes} signal is produced. The amount of light which is emitted from an oil burner flame depends upon the amount of {open_quotes}soot{close_quotes} or carbon in the flame, the size and shape of the flame, and the flame temperature. The quality of flame is practically judged by the amount of soot which it is producing and for this reason it is necessary to eliminate effects of other parameters. Temperature is expected to be the most important of these. The FQI eliminates effects due to the chamber environment by establishing a set point for each specific appliance. The transient temperature effects are accounted for by examining the flame brightness only at a single time during the firing cycle. BNL is currently involved with the development of a two-color approach to the monitoring of flame quality. The basic concept involved is the measurement of both flame temperature and total amount of light emitted to allow a more direct estimate to be made of the amount of soot being produced and so the flame quality. The objective is to develop a more sensitive measurement which may be more universally applicable. This paper provides a summary of our approach and results to date in this project.

  1. Two-color walking Peregrine solitary waves.

    Science.gov (United States)

    Baronio, Fabio; Chen, Shihua; Mihalache, Dumitru

    2017-09-15

    We study the extreme localization of light, evolving upon a non-zero background, in two-color parametric wave interaction in nonlinear quadratic media. We report the existence of quadratic Peregrine solitary waves, in the presence of significant group-velocity mismatch between the waves (or Poynting vector beam walk-off), in the regime of cascading second-harmonic generation. This finding opens a novel path for the experimental demonstration of extreme rogue waves in ultrafast quadratic nonlinear optics.

  2. High speed sampling circuit design for pulse laser ranging

    Science.gov (United States)

    Qian, Rui-hai; Gao, Xuan-yi; Zhang, Yan-mei; Li, Huan; Guo, Hai-chao; Guo, Xiao-kang; He, Shi-jie

    2016-10-01

    In recent years, with the rapid development of digital chip, high speed sampling rate analog to digital conversion chip can be used to sample narrow laser pulse echo. Moreover, high speed processor is widely applied to achieve digital laser echo signal processing algorithm. The development of digital chip greatly improved the laser ranging detection accuracy. High speed sampling and processing circuit used in the laser ranging detection system has gradually been a research hotspot. In this paper, a pulse laser echo data logging and digital signal processing circuit system is studied based on the high speed sampling. This circuit consists of two parts: the pulse laser echo data processing circuit and the data transmission circuit. The pulse laser echo data processing circuit includes a laser diode, a laser detector and a high sample rate data logging circuit. The data transmission circuit receives the processed data from the pulse laser echo data processing circuit. The sample data is transmitted to the computer through USB2.0 interface. Finally, a PC interface is designed using C# language, in which the sampling laser pulse echo signal is demonstrated and the processed laser pulse is plotted. Finally, the laser ranging experiment is carried out to test the pulse laser echo data logging and digital signal processing circuit system. The experiment result demonstrates that the laser ranging hardware system achieved high speed data logging, high speed processing and high speed sampling data transmission.

  3. Calibration of Short Range 2D Laser Range Finder for 3D SLAM Usage

    OpenAIRE

    Petr Olivka; Michal Krumnikl; Pavel Moravec; David Seidl

    2016-01-01

    The laser range finder is one of the most essential sensors in the field of robotics. The laser range finder provides an accurate range measurement with high angular resolution. However, the short range scanners require an additional calibration to achieve the abovementioned accuracy. The calibration procedure described in this work provides an estimation of the internal parameters of the laser range finder without requiring any special three-dimensional targets. This work presents the use of...

  4. Testing Lorentz symmetry with Lunar Laser Ranging

    CERN Document Server

    Bourgoin, A; Bouquillon, S; Poncin-Lafitte, C Le; Francou, G; Angonin, M -C

    2016-01-01

    Lorentz symmetry violations can be parametrized by an effective field theory framework that contains both General Relativity (GR) and the Standard Model of particle physics called the Standard-Model Extension (SME). We present new constraints on pure gravity SME coefficients obtained by analyzing Lunar Laser Ranging (LLR) observations. We use a new numerical lunar ephemeris computed in the SME framework and we perform a LLR data analysis using a set of 20721 normal points covering the period August 1969 to December 2013. We emphasize that linear combination of SME coefficients to which LLR data are sensitive are not the same as those fitted in previous post-fit residuals analysis using LLR observations and based on theoretical grounds. We found no evidence for Lorentz violation at the level of $10^{-8}$ for $\\bar{s}^{TX}$, $10^{-12}$ for $\\bar{s}^{XY}$ and $\\bar{s}^{XZ}$, $10^{-11}$ for $\\bar{s}^{XX}-\\bar{s}^{YY}$ and $\\bar{s}^{XX}+\\bar{s}^{YY}-2\\bar{s}^{ZZ}-0.045\\bar{s}^{YZ}$ and $10^{-9}$ for $\\bar{s}^{TY}+...

  5. Testing Lorentz Symmetry with Lunar Laser Ranging

    Science.gov (United States)

    Bourgoin, A.; Hees, A.; Bouquillon, S.; Le Poncin-Lafitte, C.; Francou, G.; Angonin, M.-C.

    2016-12-01

    Lorentz symmetry violations can be parametrized by an effective field theory framework that contains both general relativity and the standard model of particle physics called the standard-model extension (SME). We present new constraints on pure gravity SME coefficients obtained by analyzing lunar laser ranging (LLR) observations. We use a new numerical lunar ephemeris computed in the SME framework and we perform a LLR data analysis using a set of 20 721 normal points covering the period of August, 1969 to December, 2013. We emphasize that linear combination of SME coefficients to which LLR data are sensitive and not the same as those fitted in previous postfit residuals analysis using LLR observations and based on theoretical grounds. We found no evidence for Lorentz violation at the level of 10-8 for s¯T X, 10-12 for s¯X Y and s¯X Z, 10-11 for s¯X X-s¯Y Y and s¯X X+s¯Y Y-2 s¯Z Z-4.5 s¯Y Z, and 10-9 for s¯T Y+0.43 s¯T Z. We improve previous constraints on SME coefficient by a factor up to 5 and 800 compared to postfit residuals analysis of respectively binary pulsars and LLR observations.

  6. Relativity Parameters Determined from Lunar Laser Ranging

    Science.gov (United States)

    Williams, J. G.; Newhall, X. X.; Dickey, J. O.

    1996-01-01

    Analysis of 24 years of lunar laser ranging data is used to test the principle of equivalence, geodetic precession, the PPN parameters beta and gamma, and G/G. Recent data can be fitted with a rms scatter of 3 cm. (a) Using the Nordtvedt effect to test the principle of equivalence, it is found that the Moon and Earth accelerate alike in the Sun's field. The relative accelerations match to within 5 x 10(exp -13) . This limit, combined with an independent determination of y from planetary time delay, gives beta. Including the uncertainty due to compositional differences, the parameter beta differs from unity by no more than 0.0014; and, if the weak equivalence principle is satisfied, the difference is no more than 0.0006. (b) Geodetic precession matches its expected 19.2 marc sec/yr rate within 0.7%. This corresponds to a 1% test of gamma. (c) Apart from the Nordtvedt effect, beta and gamma can be tested from their influence on the lunar orbit. It is argued theoretically that the linear combination 0.8(beta) + 1.4(gamma) can be tested at the 1% level of accuracy. For solutions using numerically derived partial derivatives, higher sensitivity is found. Both 6 and y match the values of general relativity to within 0.005, and the linear combination beta+ gamma matches to within 0,003, but caution is advised due to the lack of theoretical understanding of these sensitivities. (d) No evidence for a changing gravitational constant is found, with absolute value of G/G less than or equal to 8 x lO(exp -12)/yr. There is significant sensitivity to G/G through solar perturbations on the lunar orbit.

  7. Relativity Parameters Determined from Lunar Laser Ranging

    Science.gov (United States)

    Williams, J. G.; Newhall, X. X.; Dickey, J. O.

    1996-01-01

    Analysis of 24 years of lunar laser ranging data is used to test the principle of equivalence, geodetic precession, the PPN parameters beta and gamma, and G/G. Recent data can be fitted with a rms scatter of 3 cm. (a) Using the Nordtvedt effect to test the principle of equivalence, it is found that the Moon and Earth accelerate alike in the Sun's field. The relative accelerations match to within 5 x 10(exp -13) . This limit, combined with an independent determination of y from planetary time delay, gives beta. Including the uncertainty due to compositional differences, the parameter beta differs from unity by no more than 0.0014; and, if the weak equivalence principle is satisfied, the difference is no more than 0.0006. (b) Geodetic precession matches its expected 19.2 marc sec/yr rate within 0.7%. This corresponds to a 1% test of gamma. (c) Apart from the Nordtvedt effect, beta and gamma can be tested from their influence on the lunar orbit. It is argued theoretically that the linear combination 0.8(beta) + 1.4(gamma) can be tested at the 1% level of accuracy. For solutions using numerically derived partial derivatives, higher sensitivity is found. Both 6 and y match the values of general relativity to within 0.005, and the linear combination beta+ gamma matches to within 0,003, but caution is advised due to the lack of theoretical understanding of these sensitivities. (d) No evidence for a changing gravitational constant is found, with absolute value of G/G less than or equal to 8 x lO(exp -12)/yr. There is significant sensitivity to G/G through solar perturbations on the lunar orbit.

  8. Experimental Validation of Ship Identification with a Laser Range Profiler

    NARCIS (Netherlands)

    Heuvel, J.C. van den; Pace, P.; Bekman, H.H.P.T.; Putten, F.J.M. van; Schleijpen, H.M.A.

    2008-01-01

    Naval operations in the littoral have to deal with threats at short range in cluttered environments with both neutral and hostile targets. There is a need for fast identification, which is possible with a laser range profiler. Additionally, in a coastal-surveillance scenario a laser range profiler

  9. Design of high-precision ranging system for laser fuze

    Science.gov (United States)

    Chen, Shanshan; Zhang, He; Xu, Xiaobin

    2016-10-01

    According to the problem of the high-precision ranging in the circumferential scanning probe laser proximity fuze, a new type of pulsed laser ranging system has been designed. The laser transmitting module, laser receiving module and ranging processing module have been designed respectively. The factors affecting the ranging accuracy are discussed. And the method of improving the ranging accuracy is studied. The high-precision ranging system adopts the general high performance microprocessor C8051FXXX as the core. And the time interval measurement chip TDC-GP21 was used to implement the system. A PCB circuit board was processed to carry on the experiment. The results of the experiment prove that a centimeter level accuracy ranging system has been achieved. The works can offer reference for ranging system design of the circumferential scanning probe laser proximity fuze.

  10. The solid state detector technology for picosecond laser ranging

    Science.gov (United States)

    Prochazka, Ivan

    1993-01-01

    We developed an all solid state laser ranging detector technology, which makes the goal of millimeter accuracy achievable. Our design and construction philosophy is to combine the techniques of single photon ranging, ultrashort laser pulses, and fast fixed threshold discrimination while avoiding any analog signal processing within the laser ranging chain. The all solid state laser ranging detector package consists of the START detector and the STOP solid state photon counting module. Both the detectors are working in an optically triggered avalanche switching regime. The optical signal is triggering an avalanche current buildup which results in the generation of a uniform, fast risetime output pulse.

  11. Two Color QCD beyond the BEC regime

    CERN Document Server

    Hands, S; Skullerud, J I; Hands, Simon; Kim, Seyong; Skullerud, Jon-Ivar

    2005-01-01

    We present results of simulations of Two Color QCD using two flavors of Wilson quark in the fundamental representation, at non-zero quark chemical potential mu, on an 8^3x16 lattice. Results for the quark number density, quark and gluon energy densities, and superfluid condensate are qualitatively distinct from the behaviour expected on the assumption that the dominant degrees of freedom are tightly bound scalar diquarks which Bose condense; rather the scaling with mu is more suggestive of a Fermi surface disrupted by a Cooper pair condensate. We also present evidence both for screening of the static potential, and color deconfinement, arising solely as a result of a non-zero quark density.

  12. Two-Color Magneto-Optical Trap with Small Magnetic Field for Ytterbium

    CERN Document Server

    Kawasaki, Akio; Yu, QinQin; Vuletić, Vladan

    2015-01-01

    We report a two-color magneto-optical trap (MOT) for ytterbium atoms operating at a low magnetic field gradient down to 2 G/cm where a conventional MOT using the singlet transition (6s^2 1S0 -> 6s6p 1P1) is unable to trap atoms. By simultaneously applying laser light on both the broad-linewidth singlet transition and the narrow-linewidth triplet transition (6s^2 1S0 -> 6s6p 3P1), we load and trap 4.0 x 10^5 atoms directly from an atomic beam at 700 K. In the two-color MOT, the slowing and trapping functions are separately performed by the singlet transition light and the triplet transition light, respectively. The two-color MOT is highly robust against laser power imbalance even at very low magnetic field gradients.

  13. Range-Gated Laser Stroboscopic Imaging for Night Remote Surveillance

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-Wei; ZHOU Yan; FAN Song-Tao; HE Jun; LIU Yu-Liang

    2010-01-01

    @@ For night remote surveillance,we present a method,the range-gated laser stroboscopic imaging(RGLSI),which uses a new kind of time delay integration mode to integrate target signals so that night remote surveillance can be realized by a low-energy illuminated laser.The time delay integration in this method has no influence on the video frame rate.

  14. Electron Correlation in Nonsequential Double Ionization of Helium by Two-Color Pulses

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yue-Ming; LIAO Qing; HUANG Cheng; TONG Ai-Hong; LU Pei-Xiang

    2010-01-01

    @@ We investigate the momentum and energy correlations between the two electrons from nonsequential double ionization(NSDI)of helium by strong two-color pulses with the classical three-dimensional ensemble model.The correlated momentum distribution in the direction parallel to the laser field exhibits an arc-like structure and the sum-energy spectrum shows a sharp peak for the NSDI of helium in the two-color fields.Back analysis reveals that the narrow time interval during which recollisions occur,the low returning energy and the short time delay between recollision and double ionization lead to the novel momentum and energy correlations.

  15. Threshold Determination and Analysis of Laser Pulse Range Finder

    Institute of Scientific and Technical Information of China (English)

    殷聪; 韩绍坤; 刘巽亮; 张化朋; 赵跃进

    2003-01-01

    Under different conditions, the highest detection probability should be acquired while receiving laser echo during laser pulse range finding. The threshold voltage of the signal detection can be set corresponding to different conditions by using resistor network. As a feedback loop, automatic noise threshold circuit could change the threshold voltage following the noise level. The threshold can track the noise closely, rapidly and accurately by adopting this combination. Therefore, the receiving capability of laser echo receiving system will be maximized, and it can detect weaker laser pulse from noise.

  16. Atmospheric Error Correction of the Laser Beam Ranging

    Directory of Open Access Journals (Sweden)

    J. Saydi

    2014-01-01

    Full Text Available Atmospheric models based on surface measurements of pressure, temperature, and relative humidity have been used to increase the laser ranging accuracy by ray tracing. Atmospheric refraction can cause significant errors in laser ranging systems. Through the present research, the atmospheric effects on the laser beam were investigated by using the principles of laser ranging. Atmospheric correction was calculated for 0.532, 1.3, and 10.6 micron wavelengths through the weather conditions of Tehran, Isfahan, and Bushehr in Iran since March 2012 to March 2013. Through the present research the atmospheric correction was computed for meteorological data in base of monthly mean. Of course, the meteorological data were received from meteorological stations in Tehran, Isfahan, and Bushehr. Atmospheric correction was calculated for 11, 100, and 200 kilometers laser beam propagations under 30°, 60°, and 90° rising angles for each propagation. The results of the study showed that in the same months and beam emission angles, the atmospheric correction was most accurate for 10.6 micron wavelength. The laser ranging error was decreased by increasing the laser emission angle. The atmospheric correction with two Marini-Murray and Mendes-Pavlis models for 0.532 nm was compared.

  17. Detection performance of laser range-gated imaging system

    Science.gov (United States)

    Xu, Jun; Li, Xiaofeng; Luo, Jijun; Zhang, Shengxiu; Xu, Yibin

    2010-10-01

    Laser radar is rapidly developing towards very capable sensors for number of applications such as military sensing and guidance, auto collision avoidance, robotic vision and atmospheric sensing. In this paper, the detection performance of non-scanned Laser Rang-gated (LRG) imaging system is studied. In order to compute the detection range of laser active imaging system, the range equation is derived by using laser illuminating model and considering factors which affect system imaging quality. According to the principle of laser radar and the characters of objects and the detectors in special applied setting, it mainly deduced the non-scanned laser radar range equation of the range-gated system, meanwhile, the SNR model of non-scanned LRG imaging system is set up. Then, relationship of the detection probability, the false alarm probability and the signal-to-noise ratio in the non-scanned LRG imaging system are analyzed, the influence factors of system's performance are pointed out, and the solution is proposed. The detection performance simulation software of non-scanned LRG imaging system is designed with MATLAB and the performance of the imaging system is simulated.

  18. Calibration of Short Range 2D Laser Range Finder for 3D SLAM Usage

    Directory of Open Access Journals (Sweden)

    Petr Olivka

    2016-01-01

    Full Text Available The laser range finder is one of the most essential sensors in the field of robotics. The laser range finder provides an accurate range measurement with high angular resolution. However, the short range scanners require an additional calibration to achieve the abovementioned accuracy. The calibration procedure described in this work provides an estimation of the internal parameters of the laser range finder without requiring any special three-dimensional targets. This work presents the use of a short range URG-04LX scanner for mapping purposes and describes its calibration. The precision of the calibration was checked in an environment with known ground truth values and the results were statistically evaluated. The benefits of the calibration are also demonstrated in the practical applications involving the segmentation of the environment. The proposed calibration method is complex and detects all major manufacturing inaccuracies. The procedure is suitable for easy integration into the current manufacturing process.

  19. Satellite laser ranging experiment with sub-centimeter single-shot ranging precision at Shanghai Observatory

    Institute of Scientific and Technical Information of China (English)

    YANG; Fumin(杨福民); CHEN; Wanzhen(陈婉珍); ZHANG; Zhongping(张忠萍); CHEN; Juping(陈菊平); HU; Jingfu(扈荆夫); LI; Xin(李鑫); I.; Prochazka; K.; Hamal

    2003-01-01

    The Shanghai Astronomical Observatory, Chinese Academy of Sciences, incollaboration with the Czech Technical University, carried out the experiment of satellite laser ranging with sub-centimeter precision in Shanghai in August 2001. A pico-second event timer was used for the measurement of the time interval between the transmitted and returned laser pulses for Lageos 1, 2, Starlette, Stella, Topex/Poseiden and ERS-2 in coordination with the existing laser transmitting and receiving system at the Shanghai Observatory. The analysis of the measurement showed that the single-shot ranging precision with these satellites is 7-8 mm. In order to compare ranging precision, the existing ranging system has tracked simultaneously these satellites and obtained the ranging precision of 12-15 mm. It means that the ranging precision with the new system is 80% better thanthe existing system. The systematic biases with the existing system have also been checked in the experiment.

  20. Identification of Littoral Targets with a Laser Range Profiler

    NARCIS (Netherlands)

    Heuvel, J.C. van den; Bekman, H.H.P.T.; Putten, F.J.M. van; Cohen, L.H.

    2007-01-01

    Naval operations in the littoral have to deal with threats at short range in cluttered environments with both neutral and hostile targets. On board naval vessels there is a need for fast identification, which is possible with a laser range profiler. Additionally, in a coast-surveillance scenario a

  1. RESEARCH ON LASER RANGE SCANNING AND ITS APPLICATION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper the development of the technology of the laserscanning is summarized.The principles of laser range scanning are introduced.Based on the laser scanning technology and methods,which are investigated by the authors to survey deposit volume,a surveying system is developed and a practical application is performed.It is shown that the laser-scanning technology has obvious advantages such as measurement precision,automation and visualization of observed data in comparison with the traditional methods.As a result,labor intensity is relieved obviously and work efficiency is promoted.

  2. Two-color, double-slit in vivo flow cytometer.

    Science.gov (United States)

    Novak, J; Puoris'haag, M

    2007-10-15

    The in vivo flow cytometer enables the real-time detection and quantification of fluorescent cells circulating within a live animal without the need for incisions or extraction of blood. It has been used in demonstrating flow velocity disparities in biological flows, and in the investigation of the circulation kinetics of various types of cells. However, a shortcoming of this in vivo flow cytometer is that it provides only one excitation slit at one wavelength, resulting in several performance limitations. Therefore, a second in vivo flow cytometer that provides two different laser wavelengths, 473 and 633 nm, and one or two excitation slits has been designed and built. Thus far, the two-color system has been used to acquire circulation kinetics data of two different cell populations each labeled with a different marker, one cell population labeled with two different markers, and one cell population expressing the green-fluorescent protein gene. In addition, accurate arterial red blood cell velocities within a mouse have been determined using the cytometer.

  3. Compact-range coordinate system established using a laser tracker.

    Energy Technology Data Exchange (ETDEWEB)

    Gallegos, Floyd H.; Bryce, Edwin Anthony

    2006-12-01

    Establishing a Cartesian coordinate reference system for an existing Compact Antenna Range using the parabolic reflector is presented. A SMX (Spatial Metrix Corporation) M/N 4000 laser-based coordinate measuring system established absolute coordinates for the facility. Electric field characteristics with positional movement correction are evaluated. Feed Horn relocation for alignment with the reflector axis is also described. Reference points are established for follow-on non-laser alignments utilizing a theodolite.

  4. Use of laser range finders and range image analysis in automated assembly tasks

    Science.gov (United States)

    Alvertos, Nicolas; Dcunha, Ivan

    1990-01-01

    A proposition to study the effect of filtering processes on range images and to evaluate the performance of two different laser range mappers is made. Median filtering was utilized to remove noise from the range images. First and second order derivatives are then utilized to locate the similarities and dissimilarities between the processed and the original images. Range depth information is converted into spatial coordinates, and a set of coefficients which describe 3-D objects is generated using the algorithm developed in the second phase of this research. Range images of spheres and cylinders are used for experimental purposes. An algorithm was developed to compare the performance of two different laser range mappers based upon the range depth information of surfaces generated by each of the mappers. Furthermore, an approach based on 2-D analytic geometry is also proposed which serves as a basis for the recognition of regular 3-D geometric objects.

  5. International Laser Ranging Service (ILRS): Terms of Reference

    Science.gov (United States)

    Husson, Van; Noll, Carey

    2000-01-01

    The International Laser Ranging Service (ILRS) is an established Service within Section II , Advanced Space Technology, of the International Association of Geodesy (IAG). The primary objective of the ILRS is to provide a service to support, through Satellite and Lunar Laser Ranging data and related products, geodetic and geophysical research activities as well as International Earth Rotation Service (IERS) products important to the maintenance of an accurate International Terrestrial Reference Frame (ITRF). The service also develops the necessary standards/specifications and encourages international adherence to its conventions.

  6. Laser-Ranging Long Baseline Differential Atom Interferometers for Space

    CERN Document Server

    Chiow, Sheng-wey; Yu, Nan

    2015-01-01

    High sensitivity differential atom interferometers are promising for precision measurements in science frontiers in space, including gravity field mapping for Earth science studies and gravitational wave detection. We propose a new configuration of twin atom interferometers connected by a laser ranging interferometer (LRI-AI) to provide precise information of the displacements between the two AI reference mirrors and a means to phase-lock the two independent interferometer lasers over long distances, thereby further enhancing the feasibility of long baseline differential atom interferometers. We show that a properly implemented LRI-AI can achieve equivalent functionality to the conventional differential atom interferometer measurement system. LRI-AI isolates the laser requirements for atom interferometers and for optical phase readout between distant locations, thus enabling optimized allocation of available laser power within a limited physical size and resource budget. A unique aspect of LRI-AI also enables...

  7. Laser Meter of Atmospheric Inhomogeneity Properties in UV Spectral Range

    Directory of Open Access Journals (Sweden)

    S. E. Ivanov

    2015-01-01

    Full Text Available Development of laser systems designed to operate in conditions of the terrestrial atmosphere demands reliable information about the atmosphere condition. The aerosol lidars for operational monitoring of the atmosphere allow us to define remotely characteristics of atmospheric aerosol and cloudy formations in the atmosphere.Today the majority of aerosol lidars run in the visible range. However, in terms of safety (first of all to eyes also ultra-violet (UF range is of interest. A range of the wavelengths of the harmful effect on the eye retina is from 0.38 to 1.4 mμ. Laser radiation with the wavelengths less than 0.38 mμ and over 1.4 mμ influences the anterior ambient of an eye and is safer, than laser radiation with the wavelengths of 0.38 – 1.4 mμ.The paper describes a laser meter to measure characteristics of atmospheric inhomogeneity propertis in UF spectral range at the wavelength of 0.355 mμ.As a radiation source, the meter uses a semiconductor-pumped pulse solid-state Nd:YAG laser. As a receiving lens, Kassegren's scheme-implemented mirror lens with a socket to connect optical fibre is used in the laser meter. Radiation from the receiving lens is transported through the optical fibre to the optical block. The optical block provides spectral selection of useful signal and conversion of optical radiation into electric signal.To ensure a possibility for alignment of the optical axes of receiving lens and laser radiator the lens is set on the alignment platform that enables changing lens inclination and turn with respect to the laser.The software of the laser meter model is developed in the NI LabVIEW 2012 graphic programming environment.The paper gives the following examples: a typical laser echo signal, which is back scattered by the atmosphere and spatiotemporal distribution of variation coefficient of the volumetric factor of the back scattered atmosphere. Results of multi-day measurements show that an extent of the recorded aerosol

  8. Observing tectonic plate motions and deformations from satellite laser ranging

    Science.gov (United States)

    Christodoulidis, D. C.; Smith, D. E.; Kolenkiewicz, R.; Klosko, S. M.; Torrence, M. H.

    1985-01-01

    The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.

  9. Laser-guide-stars used for cophasing broad capture ranges

    CERN Document Server

    Martinez,

    2016-01-01

    Segmented primary mirrors are indispensable to master the steady increase in spatial resolution. Phasing optics systems must reduce segment misalignments to guarantee the high optical quality required for astronomical science programs. Modern telescopes routinely use adaptive optics systems to compensate for the atmosphere and use laser-guide-stars to create artificial stars as bright references in the field of observation. Because multiple laser-guide-star adaptive optics are being implemented in all major observatories, we propose to use man-made stars not only for adaptive optics, but for phasing optics. We propose a method called the doublet-wavelength coherence technique (DWCT), exploiting the D lines of sodium in the mesosphere using laser guide-stars. The signal coherence properties are then used. The DWCT capture range exceeds current abilities by a factor of 100. It represents a change in paradigm by improving the phasing optics capture range from micrometric to millimetric. It thereby potentially el...

  10. Observing tectonic plate motions and deformations from satellite laser ranging

    Science.gov (United States)

    Christodoulidis, D. C.; Smith, D. E.; Kolenkiewicz, R.; Klosko, S. M.; Torrence, M. H.

    1985-01-01

    The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.

  11. A Comparison of Close-Range Photogrammetry to Terrestrial Laser ...

    African Journals Online (AJOL)

    Julian Smit

    In a separate process a laser scanner was used to scan the ... image photography is widely accepted as the optimal method in close-range .... Once the interest points have been determined by convolution in the x- and y- directions, they.

  12. Location Of A Vehicle With A Laser Range Finder

    Science.gov (United States)

    Zhao, C. J.; Monchaud, S.; Marce, L.; Julliere, M.

    1984-02-01

    Absolute location of a mobile robot is necessary to improve the autonomy of vehicle built for hostile environments. We are developing a scanning laser range finder based on triangulation to get range data about the edges of a cylindrical polyhedral world. From the matching between the measurements and data computed from a model of the a priori known environment, the position of the robot is deduced accurately.

  13. 双波长飞秒激光抽运-探测法测量纳米薄膜及界面热物性%Two-Color Femto-second Laser Pump and Probe Thermoreflectance Method Measuring Nano-Film Thermal Conductivity and Interface Thermal Conductance

    Institute of Scientific and Technical Information of China (English)

    祝捷; 唐大伟

    2012-01-01

    建立了用来研究时间空间微尺度传热现象的双波长飞秒激光抽运-探测热反射系统,与常规的单波长飞秒激光抽运探测系统相比,双波长的光路设计方案可以大幅提高信噪比,并使共线的聚焦光路更易实现,从而提高测量的准确度。建立了与实验测量过程相应的多层膜热传导模型,并实现了多参数拟合,可用于对体材料或薄膜材料的热导率以及界面热导的准确测量。本文采用这种先进的测量方法测量了SiO_2纳米薄膜的热导率及其与Si之间的界面热导。%A two-color femto-second laser pump and probe thermoreflectance system has been established for studying the micro-scale heat transfer.Compared with single-color system,this two-color scheme could highly increase the signal-to-noise ratio,and make it easier to realize the co-line focus design.As a result,the accuracy of the measurement would be increased.A model with regard to the heat transfer process has also been established and used to obtain the thermal conductivity of bulk or film samples,as well as interface thermal conductance.This system has been successfully used to measure the thermal conductivity of SiO_2 nano-film and the interface thermal conductance between SiO_2 and Si substrate.

  14. Speckle phase noise in coherent laser ranging: fundamental precision limitations.

    Science.gov (United States)

    Baumann, Esther; Deschênes, Jean-Daniel; Giorgetta, Fabrizio R; Swann, William C; Coddington, Ian; Newbury, Nathan R

    2014-08-15

    Frequency-modulated continuous-wave laser detection and ranging (FMCW LADAR) measures the range to a surface through coherent detection of the backscattered light from a frequency-swept laser source. The ultimate limit to the range precision of FMCW LADAR, or any coherent LADAR, to a diffusely scattering surface will be determined by the unavoidable speckle phase noise. Here, we demonstrate the two main manifestations of this limit. First, frequency-dependent speckle phase noise leads to a non-Gaussian range distribution having outliers that approach the system range resolution, regardless of the signal-to-noise ratio. These outliers are reduced only through improved range resolution (i.e., higher optical bandwidths). Second, if the range is measured during a continuous lateral scan across a surface, the spatial pattern of speckle phase is converted to frequency noise, which leads to additional excess range uncertainty. We explore these two effects and show that laboratory results agree with analytical expressions and numerical simulations. We also show that at 1 THz optical bandwidth, range precisions below 10 μm are achievable regardless of these effects.

  15. Study of pseudo noise CW diode laser for ranging applications

    Science.gov (United States)

    Lee, Hyo S.; Ramaswami, Ravi

    1992-11-01

    A new Pseudo Random Noise (PN) modulated CW diode laser radar system is being developed for real time ranging of targets at both close and large distances (greater than 10 KM) to satisy a wide range of applications: from robotics to future space applications. Results from computer modeling and statistical analysis, along with some preliminary data obtained from a prototype system, are presented. The received signal is averaged for a short time to recover the target response function. It is found that even with uncooperative targets, based on the design parameters used (200-mW laser and 20-cm receiver), accurate ranging is possible up to about 15 KM, beyond which signal to noise ratio (SNR) becomes too small for real time analog detection.

  16. Lunar Laser Ranging Experiment for Japanese SELENE-2 landing mission

    Science.gov (United States)

    Noda, H.; Kunimori, H.; Araki, H.; Fuse, T.; Hanada, H.; Katayama, M.; Otsubo, T.; Sasaki, S.; Tazawa, S.; Tsuruta, S.; Funazaki, K.; Taniguchi, H.; Murata, K.

    2012-04-01

    We present the development status of the Lunar Laser Ranging experiment proposed to Japanese SELENE-2 lunar landing mission. The Lunar Laser Ranging measures the distance between laser link stations on the Earth and retroreflectors on the Moon, by detecting the time of flight of photons of high-powered laser emitted from the ground station. Since the Earth-Moon distance contains information of lunar orbit, lunar solid tides, and lunar orientation and rotation, we can estimate the inner structure of the Moon through orientation, rotation and tide. Retroreflectors put by the Apollo and Luna missions in 1970's are arrays of many small Corner Cube Prisms (CCP). Because of the tilt of these arrays from the Earth direction due to the optical libration, the returned laser pulse is broaden, causing the main range error of more than 1.5 cm ([1]). Therefore retroreflectors with larger single aperture are necessary for more accurate ranging, and we propose a large single retroreflector of hollow-type with 15 cm aperture. Larger aperture up to 20 cm might be favorable if more mass is permitted for payloads. To cancel the velocity aberration, a large, single aperture retroreflector needs small amount of offset angle between the reflecting planes to spoil the return beam pattern. This angle offset, called Dihedral Angle Offset (DAO) must be optimized to be less than 1 second of arc with 0.1 seconds of arc accuracy to accumulate more photons [2, 3]. The realization of such small DAO is challenging with current technology, therefore the development of fabrication method is important. As for the mirror material, some ceramic products (ZPF: Zero-expansion Pore-free ceramics or SiC: silicon carbide) are under consideration in terms of weight, hardness and handling. The thermal quality of the material can be evaluated by both the thermal conductivity and the coefficient of thermal expansion. The method to fasten three planes each other with precise DAO must be developed.

  17. Note: Digital laser frequency auto-locking for inter-satellite laser ranging.

    Science.gov (United States)

    Luo, Yingxin; Li, Hongyin; Yeh, Hsien-Chi

    2016-05-01

    We present a prototype of a laser frequency auto-locking and re-locking control system designed for laser frequency stabilization in inter-satellite laser ranging system. The controller has been implemented on field programmable gate arrays and programmed with LabVIEW software. The controller allows initial frequency calibrating and lock-in of a free-running laser to a Fabry-Pérot cavity. Since it allows automatic recovery from unlocked conditions, benefit derives to automated in-orbit operations. Program design and experimental results are demonstrated.

  18. Simultaneous measurement of temperature and velocity of air flow over 1000°C using two color phosphor thermometry

    Science.gov (United States)

    Fukuta, Masatoshi; Someya, Satoshi; Munakata, Tetsuo; LCS Team

    2016-11-01

    Thermal barrier coatings were applied to the gas turbines and the internal combustion engines for the high thermal efficiency. The evaluation and the improvement of coatings require to measure transient gaseous flow near the wall with coatings. An aim of this study is to combine a two color phosphor thermometry with the PIV to measure simultaneously temperature and velocity of the gas over 1000°C. The temperature and velocity distribution of an impinging jet of high temperature air was simultaneously visualized in experiments. The temperature was estimated from an intensity ratio of luminescent in different ranges of wavelength, 500 600 nm and 400 480 nm. Uncertainty of measured temperature was less than 10°C. Temperatures measured by the developed method and by thermocouples were agreed well. The measured velocity by the PIV with phosphor particles were also agreed well with the velocity measured by a Laser Doppler Velocimeter.

  19. Opportunities for two-color experiments at the SASE3 undulator line of the European XFEL

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca; Mazza, Tommaso; Meyer, Michael; Serkez, Svitozar [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2017-06-15

    X-ray Free Electron Lasers (XFELs) have been proven to generate short and powerful radiation pulses allowing for a wide class of novel experiments. If an XFEL facility supports the generation of two X-ray pulses with different wavelengths and controllable delay, the range of possible experiments is broadened even further to include X-ray-pump/X-ray-probe applications. In this work we discuss the possibility of applying a simple and cost-effective method for producing two-color pulses at the SASE3 soft X-ray beamline of the European XFEL. The technique is based on the installation of a magnetic chicane in the baseline undulator and can be accomplished in several steps. We discuss the scientific interest of this upgrade for the Small Quantum Systems (SQS) instrument, in connection with the high-repetition rate of the European XFEL, and we provide start-to-end simulations up to the radiation focus on the sample, proving the feasibility of our concept.

  20. Semiconductor cluster beams: One and two color ionization studies of Six and Gex

    OpenAIRE

    Heath, J R; Liu, Yuan; O'Brien, S. C.; Zhang, Qing-ling; Curl, R. F.; Tittel, F.K.; Smalley, R.E.

    1985-01-01

    Supersonic beams of clusters of Si and Ge atoms have been produced by laser vaporization followed by supersonic expansion in a helium carrier. The cluster beams were characterized by F2(7.9 eV) and ArF(6.4 eV) excimer laser ionization accompanied by time-of-flight mass analysis. In addition, the feasibility of a resonant two-photon ionization (R2PI) spectroscopic study was explored by two-color experiments involving initial excitation with the second (2.36 eV) and third (3.54 eV) harmonics of...

  1. Laser beaming demonstrations at the Starfire Optical Range

    Energy Technology Data Exchange (ETDEWEB)

    Lipinski, R.J.; Meister, D.C.; Tucker, S. [Sandia National Labs., Albuquerque, NM (United States); Leatherman, P.; Fugate, R.Q.; Maes, C.; Lange, W.J.; Cowan, W. [Air Force Phillips Lab./LIG, Kirtland Air Force Base, NM (United States). Starfire Optical Range; Cleis, R.A.; Spinhirne, J.M. [Rockwell Power Systems, Albuquerque, NM (United States). Starfire Optical Range] [and others

    1995-03-01

    The ability to acquire, track, and accurately direct a laser beam to a satellite is crucial for power-beaming and laser-communications. To assess the state of the art in this area, a team consisting of Air Force Phillips Laboratory, Sandia National Laboratories, and COMSAT Corporation personnel performed some laser beaming demonstrations to various satellites. A ruby laser and a frequency-doubled YAG laser were used with the Phillips Lab Starfire Optical Range (SOR) beam director for this activity. The ruby laser projected 20 J in 6 ms out the telescope with a beam divergence that increased from 1.4 to 4 times the diffraction limit during that time. The doubled YAG projected 0.09 J in 10 ns at 20 Hz. The SOR team demonstrated the ability to move rapidly to a satellite, center it in the telescope, then lock onto it with the tracker, and establish illumination. Several low-earth-orbit satellites with corner-cube retro-reflectors were illuminated at ranges from 1000 to 6000 km with a beam divergence estimated to be about 20 {mu}radians. The return signal from the ruby laser was collected in a 15-cm telescope, detected by a photomultiplier tube, and recorded at 400 kHz. Rapid variations in intensity (as short at 15 {mu}s) were noted, which may be due to speckles caused by phase interference from light reflected from different retro-reflectors on the satellite. The return light from the YAG was collected by a 35-cm telescope and detected by an intensified CCD camera. The satellite brightened by about a factor of 30 in the sunlight when the laser was turned on, and dimmed back to normal when the 50-{mu}radian point-ahead was turned off. The satellite was illuminated at 1 Hz as it entered the earth`s shadow and followed for about 10 seconds in the shadow. In another demonstration, four neighboring GEO satellites were located and centered in succession with a 3.5-m telescope at a rate of about 16 seconds per satellite.

  2. Ranging with frequency-shifted feedback lasers: from μm-range accuracy to MHz-range measurement rate

    Science.gov (United States)

    Kim, J. I.; Ogurtsov, V. V.; Bonnet, G.; Yatsenko, L. P.; Bergmann, K.

    2016-12-01

    We report results on ranging based on frequency-shifted feedback (FSF) lasers with two different implementations: (1) An Ytterbium-fiber system for measurements in an industrial environment with accuracy of the order of 1 μm, achievable over a distance of the order of meters with potential to reach an accuracy of better than 100 nm; (2) A semiconductor laser system for a high rate of measurements with an accuracy of 2 mm @ 1 MHz or 75 μm @ 1 kHz and a limit of the accuracy of ≥10 μm. In both implementations, the distances information is derived from a frequency measurement. The method is therefore insensitive to detrimental influence of ambient light. For the Ytterbium-fiber system, a key feature is the injection of a single-frequency laser, phase modulated at variable frequency Ω, into the FSF-laser cavity. The frequency Ω_{max} at which the detector signal is maximal yields the distance. The semiconductor FSF-laser system operates without external injection seeding. In this case, the key feature is frequency counting that allows convenient choice of either accuracy or speed of measurements simply by changing the duration of the interval during which the frequency is measured by counting.

  3. Ranging with frequency-shifted feedback lasers: from $\\mu$m-range accuracy to MHz-range measurement rate

    CERN Document Server

    Kim, J I; Bonnet, G; Yatsenko, L P; Bergmann, K

    2016-01-01

    We report results on ranging based on frequency shifted feedback (FSF) lasers with two different implementations: (1) An Ytterbium-fiber system for measurements in an industrial environment with accuracy of the order of 1 $\\mu$m, achievable over a distance of the order of meters with potential to reach an accuracy of better than 100 nm; (2) A semiconductor laser system for a high rate of measurements with an accuracy of 2 mm @ 1 MHz or 75 $\\mu$m @ 1 kHz and a limit of the accuracy of $\\geq $ 10 $\\mu$m. In both implementations, the distances information is derived from a frequency measurement. The method is therefore insensitive to detrimental influence of ambient light. For the Ytterbium-fiber system a key feature is the injection of a single frequency laser, phase modulated at variable frequency $\\Omega$, into the FSF-laser cavity. The frequency $\\Omega_{max}$ at which the detector signal is maximal yields the distance. The semiconductor FSF laser system operates without external injection seeding. In this c...

  4. Current Trends and Challenges in Satellite Laser Ranging

    Science.gov (United States)

    Appleby, Graham M.; Bianco, Giuseppe; Noll, Carey E.; Pavlis, Erricos C.; Pearlman, Michael R.

    2016-12-01

    Satellite Laser Ranging (SLR) is used to measure accurately the distance from ground stations to retro-reflectors on satellites and on the Moon. SLR is one of the fundamental space-geodetic techniques that define the International Terrestrial Reference Frame (ITRF), which is the basis upon which many aspects of global change over space, time, and evolving technology are measured; with VLBI the two techniques define the scale of the ITRF; alone the SLR technique defines its origin (geocenter). The importance of the reference frame has recently been recognized at the inter-governmental level through the United Nations, which adopted in February 2015 the Resolution "Global Geodetic Reference Frame for Sustainable Development." Laser Ranging provides precision orbit determination and instrument calibration and validation for satellite-borne altimeters for the better understanding of sea level change, ocean dynamics, ice mass-balance, and terrestrial topography. It is also a tool to study the dynamics of the Moon and fundamental constants and theories. With the exception of the currently in-orbit GPS constellation, all GNSS satellites now carry retro-reflectors for improved orbit determination, harmonization of reference frames, and in-orbit co-location and system performance validation; the next generation of GPS satellites due for launch from 2019 onwards will also carry retro-reflectors. The ILRS delivers weekly realizations that are accumulated sequentially to extend the ITRF and the Earth Orientation Parameter series with a daily resolution. SLR technology continues to evolve towards the next-generation laser ranging systems and it is expected to successfully meet the challenges of the GGOS2020 program for a future Global Space Geodetic Network. Ranging precision is improving as higher repetition rate, narrower pulse lasers, and faster detectors are implemented within the network. Automation and pass interleaving at some stations is expanding temporal coverage and

  5. A picosecond resolution Time Digitizer for laser ranging

    Science.gov (United States)

    Turko, B.

    1978-01-01

    The Time Digitizer capable of covering a range of 0.34 sec in 9.76 psec increments is described. The time interval between a pair of start-stop pulses is digitized coarsely in 20 nsec periods by a very accurate 50 MHz reference clock. The residual fractions of a clock period at the start and the stop end of the measured interval are stretched in two interpolators and digitized in 9.76 psec increments. An equivalent digitizing frequency of 102.4 GHz is thus achieved. The digitizer is built in a minicrate and communicates via a standard crate controller. It is intended for use in the laser ranging between ground stations and the Laser Geodetic Satellite (LAGEOS). It is shown that the distribution in any two adjacent 9.76 psec channels of a small number of identical test time intervals is essentially binomial. The performance of the digitizer and test results are given.

  6. The study of two-color excitation upconversion of Pr(0.5)Yb(3):ZBLAN

    Institute of Scientific and Technical Information of China (English)

    CHEN; Xiaobo; SONG; Zengfu

    2006-01-01

    The excited state absorption upconversion of Pr(0.5)Yb(3):ZBLAN glass material, under two-color excitation of the 960 nm semiconductor laser and the Xe lamp light simultaneously, is reported in this article. It was found that the upconversion emission spectra of 480.1, 519.0, 601.9 and 631.8 nm coincide with the common emission spectra. Meanwhile, the upconversion-excitation spectrum has three obvious peaks under two-color excitation, and they respectively correspond to the 856.0 nm upconversion excitation transition [1G4(Pr3+)→1I6(Pr3+) and 1G4(Pr3+)→3P1(Pr3+)], the 789.0 nm upconversion excitation transition 1G4(Pr3+)→3P2(Pr3+), and the 803.7 nm upconversion excitation transition 3H6(Pr3+)→1D2(Pr3+). The upconversion excitation transition 1G4(Pr3+)→1I6(Pr3+) is strong because its oscillator strength f = 23.040(10-6 is large, which results in a large peak appearing in the upconversion excitation spectrum. That is just the new interesting two-color excitation upconversion luminescence phenomenon of Pr(0.5)Yb(3):ZBLAN induced by one laser and one continuous normal light simultaneously.

  7. Two-color infrared FEL facility employing a 250-MeV linac injector of Saga synchrotron light source

    CERN Document Server

    Tomimasu, T; Koga, N; Hashiguchi, Y; Ochiai, Y; Ishibashi, M

    2001-01-01

    A two-color infrared free electron laser (FEL) facility is proposed. This FEL facility will employ a new 250-MeV linac injector of the Saga synchrotron light source (SLS). The linac has two operation modes: short macropulse mode of 1 mu s at 250 MeV is for injection to a 1.4-GeV storage ring and long macropulse mode of 13 mu s at 40 MeV is for the two-color FEL facility. The two-color FEL uses a single electron beam and simultaneously provides both infrared (IR) and far-IR laser pulses for pump-probe studies of quantum-well structures and studying vibrational relaxation of molecules. The Saga SLS will be operated in 2004 to promote material science, bio-medical and industrial applications in Kyushu.

  8. Modeling and Analysis of the APOLLO Lunar Laser Ranging Data

    CERN Document Server

    Reasenberg, R D; Colmenares, N R; Johnson, N H; Murphy, T W; Shapiro, I I

    2016-01-01

    The Earth-Moon-Sun system has traditionally provided the best laboratory for testing the strong equivalence principle. For a decade, the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) has been producing the world's best lunar laser ranging data. At present, a single observing session of about an hour yields a distance measurement with uncertainty of about 2~mm, an order of magnitude advance over the best pre-APOLLO lunar laser ranging data. However, these superb data have not yet yielded scientific results commensurate with their accuracy, number, and temporal distribution. There are two reasons for this. First, even in the relatively clean environment of the Earth-Moon system, a large number of effects modify the measured distance importantly and thus need to be included in the analysis model. The second reason is more complicated. The traditional problem with the analysis of solar-system metric data is that the physical model must be truncated to avoid extra parameters that would increase t...

  9. Characteristic Study of Third Harmonic Generation Induced by Two-Color-Field Femtosecond Laser in Air as a Function of Temporal Delay%空气中双色场激光诱导三次谐波随时间延迟变化特性的理论研究

    Institute of Scientific and Technical Information of China (English)

    刘岩; 刘伟伟

    2011-01-01

    This paper theoretically studies the spectral characteristics of the third harmonic generated (THG) in air by focusing a two-color-field laser, which is synthesized by a femtosecond laser pulse (ω0) and its second harmonic (2ω0). It is found that the third harmonic intensity varies as a function of the temporal delay between the fundamental and the second harmonic wave, showing a pronounced periodic modulation. This observation is explained by the interference taking place between two third harmonic sources. One is induced by the direct third harmonic generation of the fundamental wave, while the other is given rise by the four-wave mixing (FWM) of the fundamental and the second harmonic waves. In addition, the third harmonic spectra are investigated when the chirp and the self-phase modulation (SPM) of the fundamental pulse and the second harmonic are taken into account. Our results can provide some key informations for the coherent control of the third harmonic generation induced by twocolor-field femtosecond laser in air.%理论研究了当基频光(ω0)和倍频光(2ω0)之间的时间延迟改变时,所产生的三次谐波(THG)的光谱特性.研究结果表明,空气中双色场飞秒激光诱导三次谐波的强度随基频光与倍频光之间的时间延迟而变化,并呈现周期性的调制现象.理论分析指出这是由于基频光的三倍频过程和基频光与倍频光的四波混频(FWM)过程两种物理机制所产生的三次谐波发生了干涉现象.同时研究了基频脉冲与倍频脉冲的啁啾和自相位调制(SPM)对于所产生的三次谐波光谱分布的影响.该研究为双色场飞秒激光诱导三次谐波的相干控制提供了基本的理论依据.

  10. Probing General Relativity and New Physics with Lunar Laser Ranging

    Science.gov (United States)

    Dell'Agnello, S.; Maiello, M.; Currie, D. G.; Boni, A.; Berardi, S.; Cantone, C.; Delle Monache, G. O.; Intaglietta, N.; Lops, C.; Garattini, M.; Martini, M.; Patrizi, G.; Porcelli, L.; Tibuzzi, M.; Vittori, R.; Bianco, G.; Coradini, A.; Dionisio, C.; March, R.; Bellettini, G.; Tauraso, R.; Chandler, J.

    2012-11-01

    Over the past 40 years, Lunar Laser Ranging (LLR, developed by the Univ. of Maryland (PI) and INFN-LNF (Co-PI)) to the Apollo Cube Corner Retroreflector (CCR) arrays have supplied almost all the significant tests of General Relativity (Currie et al., 2009 [12]). LLR can evaluate the PPN (Post Newtonian Parameters), addressing this way both the possible changes in the gravitational constant and the self-energy properties of the gravitational field. In addition, the LLR has provided significant information on the composition and origin of the Moon. This is the only Apollo experiment that is still in operation. Initially the Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Over the decades, the ranging capabilities of the ground stations have improved by more than two orders of magnitude. Now, because of the lunar librations, the existing Apollo retroreflector arrays contribute a significant fraction of the limiting errors in the range measurements. We built a new experimental apparatus (the ‘Satellite/Lunar Laser Ranging Characterization Facility', SCF) and created a new test procedure (the SCF-Test) to characterize and model the detailed thermal behavior and the optical performance of cube corner laser retroreflectors in space for industrial and scientific applications (Dell'Agnello et al., 2011 [13]). Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP) and the temperature distribution of the SLR retroreflector payload under thermal conditions produced with a close-match solar simulator. The apparatus includes infrared cameras for non-invasive thermometry, thermal control and real-time movement of the payload to experimentally simulate satellite orientation on orbit with respect to both solar illumination and laser interrogation beams. These unique capabilities provide experimental validation of the space segment for SLR and Lunar Laser Ranging (LLR). The

  11. Probing General Relativity and New Physics with Lunar Laser Ranging

    Energy Technology Data Exchange (ETDEWEB)

    Dell' Agnello, S. [Laboratori Nazionali di Frascati (LNF) dell' INFN, Frascati, Rome (Italy); Maiello, M., E-mail: mauro.maiello@lnf.infn.it [Laboratori Nazionali di Frascati (LNF) dell' INFN, Frascati, Rome (Italy); Currie, D.G. [University of Maryland (UMD), College Park, MD (United States); Boni, A.; Berardi, S.; Cantone, C.; Delle Monache, G.O.; Intaglietta, N.; Lops, C.; Garattini, M.; Martini, M.; Patrizi, G.; Porcelli, L.; Tibuzzi, M. [Laboratori Nazionali di Frascati (LNF) dell' INFN, Frascati, Rome (Italy); Vittori, R. [Aeronautica Militare Italiana (AMI), Rome (Italy); Agenzia Spaziale Italiana (ASI), Rome (Italy); Bianco, G. [ASI-Centro di Geodesia Spaziale, Matera (Italy); Coradini, A. [INAF-Istituto di Fisica dello Spazio Interplanetario (IFSI), Via Fosso del Cavaliere 100, 00133 Rome (Italy); Dionisio, C. [Rheinmetall Italia S.p.A., Via Affile 102, 00131 Rome (Italy); March, R. [INFN-LNF and CNR-Istituto per le Applicazioni del Calcolo (IAC), Viale del Policlinico 137, 00161 Rome (Italy); Bellettini, G. [INFN-LNF and Department of Mathematics, University of Rome ' Tor Vergata' , Via della Ricerca Scientifica, 00133 Rome (Italy); and others

    2012-11-11

    Over the past 40 years, Lunar Laser Ranging (LLR, developed by the Univ. of Maryland (PI) and INFN-LNF (Co-PI)) to the Apollo Cube Corner Retroreflector (CCR) arrays have supplied almost all the significant tests of General Relativity (Currie et al., 2009 [12]). LLR can evaluate the PPN (Post Newtonian Parameters), addressing this way both the possible changes in the gravitational constant and the self-energy properties of the gravitational field. In addition, the LLR has provided significant information on the composition and origin of the Moon. This is the only Apollo experiment that is still in operation. Initially the Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Over the decades, the ranging capabilities of the ground stations have improved by more than two orders of magnitude. Now, because of the lunar librations, the existing Apollo retroreflector arrays contribute a significant fraction of the limiting errors in the range measurements. We built a new experimental apparatus (the 'Satellite/Lunar Laser Ranging Characterization Facility', SCF) and created a new test procedure (the SCF-Test) to characterize and model the detailed thermal behavior and the optical performance of cube corner laser retroreflectors in space for industrial and scientific applications (Dell'Agnello et al., 2011 [13]). Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP) and the temperature distribution of the SLR retroreflector payload under thermal conditions produced with a close-match solar simulator. The apparatus includes infrared cameras for non-invasive thermometry, thermal control and real-time movement of the payload to experimentally simulate satellite orientation on orbit with respect to both solar illumination and laser interrogation beams. These unique capabilities provide experimental validation of the space segment for SLR and Lunar Laser Ranging

  12. Combining Digital Watermarks with Two-Color Bitmap Image

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A technology for combining digital watermarks with two-color bitmap image based on the threshold watermarking method is presented. Our technology doesn't add any thing to the digital media, but combines the watermarks in two-color bitmap image by looking for some characteristic values in the bitmap and uses the relationship between the watermarks and the characteristic values to prove the copyright protection. The choice of the characteristic values depends on the choice of a cryptographic key known by the owner of the bitmap. The benefit of using a cryptographic key is to combine the watermarks with the bitmap in a high secure way.

  13. MOONLIGHT: A NEW LUNAR LASER RANGING RETROREFLECTOR INSTRUMENT

    Directory of Open Access Journals (Sweden)

    M. Garattini

    2013-12-01

    Full Text Available Since 1969 Lunar Laser Ranging (LLR to the Apollo Cube Corner Reflector (CCR arrays has supplied several significant tests of gravity: Geodetic Precession, the Strong and Weak Equivalence Principle (SEP, WEP, the Parametrized Post Newtonian (PPN parameter , the time change of the Gravitational constant (G, 1/r2 deviations and new gravitational theories beyond General Relativity (GR, like the unified braneworld theory (G. Dvali et al., 2003. Now a new generation of LLR can do better using evolved laser retroreflectors, developed from tight collaboration between my institution, INFN–LNF (Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali di Frascati, and Douglas Currie (University of Maryland, USA, one of the fathers of LLR. The new lunar CCR is developing and characterizing at the “Satellite/Lunar laser ranging Characterization Facility” (SCF, in Frascati, performing our new industry standard space test procedure, the “SCF-Test”; this work contains the experimental results of the SCF-Test applied to the new lunar CCR, and all the new payload developments, including the future SCF tests. The International Lunar Network (ILN research project considers our new retroreflector as one of the possible “Core Instruments”

  14. Laser Ranging to the Lost Lunokhod~1 Reflector

    CERN Document Server

    Murphy, T W; Battat, J B R; Hoyle, C D; Johnson, N H; McMillan, R J; Michelsen, E L; Stubbs, C W; Swanson, H E

    2011-01-01

    In 1970, the Soviet Lunokhod 1 rover delivered a French-built laser reflector to the Moon. Although a few range measurements were made within three months of its landing, these measurements---and any that may have followed---are unpublished and unavailable. The Lunokhod 1 reflector was, therefore, effectively lost until March of 2010 when images from the Lunar Reconnaissance Orbiter (LRO) provided a positive identification of the rover and determined its coordinates with uncertainties of about 100 m. This allowed the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) to quickly acquire a laser signal. The reflector appears to be in excellent condition, delivering a signal roughly four times stronger than its twin reflector on the Lunokhod 2 rover. The Lunokhod 1 reflector is especially valuable for science because it is closer to the Moon's limb than any of the other reflectors and, unlike the Lunokhod 2 reflector, we find that it is usable during the lunar day. We report the selenographic positi...

  15. Detecting Topological Defect Dark Matter Using Coherent Laser Ranging System.

    Science.gov (United States)

    Yang, Wanpeng; Leng, Jianxiao; Zhang, Shuangyou; Zhao, Jianye

    2016-07-08

    In the last few decades, optical frequency combs with high intensity, broad optical bandwidth, and directly traceable discrete wavelengths have triggered rapid developments in distance metrology. However, optical frequency combs to date have been limited to determine the absolute distance to an object (such as satellite missions). We propose a scheme for the detection of topological defect dark matter using a coherent laser ranging system composed of dual-combs and an optical clock via nongravitational signatures. The dark matter field, which comprises a defect, may interact with standard model particles, including quarks and photons, resulting in the alteration of their masses. Thus, a topological defect may function as a dielectric material with a distinctive frequency-depend index of refraction, which would cause the time delay of a periodic extraterrestrial or terrestrial light. When a topological defect passes through the Earth, the optical path of long-distance vacuum path is altered, this change in optical path can be detected through the coherent laser ranging system. Compared to continuous wavelength(cw) laser interferometry methods, dual-comb interferometry in our scheme excludes systematic misjudgement by measuring the absolute optical path length.

  16. 3D sensor for indirect ranging with pulsed laser source

    Science.gov (United States)

    Bronzi, D.; Bellisai, S.; Villa, F.; Scarcella, C.; Bahgat Shehata, A.; Tosi, A.; Padovini, G.; Zappa, F.; Tisa, S.; Durini, D.; Weyers, S.; Brockherde, W.

    2012-10-01

    The growing interest for fast, compact and cost-effective 3D ranging imagers for automotive applications has prompted to explore many different techniques for 3D imaging and to develop new system for this propose. CMOS imagers that exploit phase-resolved techniques provide accurate 3D ranging with no complex optics and are rugged and costeffective. Phase-resolved techniques indirectly measure the round-trip return of the light emitted by a laser and backscattered from a distant target, computing the phase delay between the modulated light and the detected signal. Singlephoton detectors, with their high sensitivity, allow to actively illuminate the scene with a low power excitation (less than 10W with diffused daylight illumination). We report on a 4x4 array of CMOS SPAD (Single Photon Avalanche Diodes) designed in a high-voltage 0.35 μm CMOS technology, for pulsed modulation, in which each pixel computes the phase difference between the laser and the reflected pulse. Each pixel comprises a high-performance 30 μm diameter SPAD, an analog quenching circuit, two 9 bit up-down counters and memories to store data during the readout. The first counter counts the photons detected by the SPAD in a time window synchronous with the laser pulse and integrates the whole echoed signal. The second counter accumulates the number of photon detected in a window shifted with respect to the laser pulse, and acquires only a portion of the reflected signal. The array is readout with a global shutter architecture, using a 100 MHz clock; the maximal frame rate is 3 Mframe/s.

  17. Coherent Laser Instrument Would Measure Range and Velocity

    Science.gov (United States)

    Chang, Daniel; Cardell, Greg; San Martin, Alejandro; Spiers, Gary

    2005-01-01

    A proposed instrument would project a narrow laser beam that would be frequency-modulated with a pseudorandom noise (PN) code for simultaneous measurement of range and velocity along the beam. The instrument performs these functions in a low mass, power, and volume package using a novel combination of established techniques. Originally intended as a low resource- footprint guidance sensor for descent and landing of small spacecraft onto Mars or small bodies (e.g., asteroids), the basic instrument concept also lends itself well to a similar application guiding aircraft (especially, small unmanned aircraft), and to such other applications as ranging of topographical features and measuring velocities of airborne light-scattering particles as wind indicators. Several key features of the instrument s design contribute to its favorable performance and resource-consumption characteristics. A laser beam is intrinsically much narrower (for the same exit aperture telescope or antenna) than a radar beam, eliminating the need to correct for the effect of sloping terrain over the beam width, as is the case with radar. Furthermore, the use of continuous-wave (CW), erbium-doped fiber lasers with excellent spectral purity (narrow line width) permits greater velocity resolution, while reducing the laser s power requirement compared to a more typical pulsed solid-state laser. The use of CW also takes proper advantage of the increased sensitivity of coherent detection, necessary in the first place for direct measurement of velocity using the Doppler effect. However, measuring range with a CW beam requires modulation to "tag" portions of it for time-of-flight determination; typically, the modulation consists of a PN code. A novel element of the instrument s design is the use of frequency modulation (FM) to accomplish both the PN-modulation and the Doppler-bias frequency shift necessary for signed velocity measurements. This permits the use of a single low-power waveguide electrooptic

  18. Advanced computer graphic techniques for laser range finder (LRF) simulation

    Science.gov (United States)

    Bedkowski, Janusz; Jankowski, Stanislaw

    2008-11-01

    This paper show an advanced computer graphic techniques for laser range finder (LRF) simulation. The LRF is the common sensor for unmanned ground vehicle, autonomous mobile robot and security applications. The cost of the measurement system is extremely high, therefore the simulation tool is designed. The simulation gives an opportunity to execute algorithm such as the obstacle avoidance[1], slam for robot localization[2], detection of vegetation and water obstacles in surroundings of the robot chassis[3], LRF measurement in crowd of people[1]. The Axis Aligned Bounding Box (AABB) and alternative technique based on CUDA (NVIDIA Compute Unified Device Architecture) is presented.

  19. Reservoir shore development in long range terrestrial laser scanning monitoring.

    Science.gov (United States)

    Kaczmarek, Halina

    2016-04-01

    Shore zones of reservoirs are in most cases very active, getting transformed as a result of coastal processes and mass movements initiated on the slopes surrounding the reservoir. From the point of view of the users of water reservoirs shore recession strongly undesirable as it causes destruction to infrastructure and buildings located in the immediate vicinity of the reservoir. For this reason, reservoir shores require continuous geodetic monitoring. Fast and accurate geodetic measurements covering shore sections several kilometers long, often in poorly accessible areas, are available using long range terrestrial laser scanning (TLS). The possibilities of using long range terrestrial laser scanning are shown on the example of the reservoir Jeziorsko on the Warta River (Central Poland). This reservoir, created in the years 1986-1992, is a typical retention reservoir, the annual fluctuations of which reach 5 m. Depending on the water level its surface area ranges from 42.3 to 19.6 km2. The width of the reservoir is 2.5 km. The total shore length of the reservoir, developed in Quaternary till and sand-till sediments, is 44.3 km, including 30.1 km of the unreinforced shore. Out of the unreinforced shore 27% is subject to coastal erosion. The cliff heights vary from a few cm to 12.5 meters, and the current rate of the cliff recession ranges from 0 to 1.12 m/y. The study used a terrestrial long range laser scanner Riegl VZ-4000 of a range of up to 4000 m. It enabled conducting the measurements of the cliff recession from the opposite shore of the reservoir, with an angular resolution of 0.002°, which gives about 50 measurement points per 1 m2. The measurements were carried out in the years 2014-2015, twice a year, in early spring before high water level, and in late autumn at a dropping water level. This allowed the separation of the impact of coastal processes and frost weathering on the cliff recession and their quantitative determination. The size and nature of

  20. Impact of Infrared Lunar Laser Ranging on Lunar Dynamics

    Science.gov (United States)

    Viswanathan, Vishnu; Fienga, Agnès; Manche, Hervé; Gastineau, Mickael; Courde, Clément; Torre, Jean-Marie; Exertier, Pierre; Laskar, Jacques; LLR Observers : Astrogeo-OCA, Apache Point, McDonald Laser Ranging Station, Haleakala Observatory, Matera Laser Ranging Observatory

    2016-10-01

    Since 2015, in addition to the traditional green (532nm), infrared (1064nm) has been the preferred wavelength for lunar laser ranging at the Calern lunar laser ranging (LLR) site in France. Due to the better atmospheric transmission of IR with respect to Green, nearly 3 times the number of normal points have been obtained in IR than in Green [ C.Courde et al 2016 ]. In our study, in addition to the historical data obtained from various other LLR sites, we include the recent IR normal points obtained from Calern over the 1 year time span (2015-2016), constituting about 4.2% of data spread over 46 years of LLR. Near even distribution of data provided by IR on both the spatial and temporal domain, helps us to improve constraints on the internal structure of the Moon modeled within the planetary ephemeris : INPOP [ Fienga et al 2015 ]. IERS recommended models have been used in the data reduction software GINS (GRGS,CNES) [ V.Viswanathan et al 2015 ]. Constraints provided by GRAIL, on the Lunar gravitational potential and Love numbers have been taken into account in the least-square fit procedure. New estimates on the dynamical parameters of the lunar core will be presented.

  1. Broadband laser ranging development at the DOE Labs

    Science.gov (United States)

    Bennett, Corey V.; La Lone, Brandon M.; Younk, Patrick W.; Daykin, Ed P.; Rhodes, Michelle A.

    2017-02-01

    Broadband Laser Ranging (BLR) is a new diagnostic being developed in collaboration across multiple USA Dept. of Energy (DOE) facilities. Its purpose is to measure the precise position of surfaces and particle clouds moving at speeds of a few kilometers per second. The diagnostic uses spectral interferometry to encode distance into a modulation in the spectrum of pulses from a mode-locked fiber laser and uses a dispersive Fourier transformation to map the spectral modulation into time. This combination enables recording of range information in the time domain on a fast oscilloscope every 25-80 ns. Discussed here are some of the hardware design issues, system tradeoffs, calibration issues, and experimental results. BLR is being developed as an add-on to conventional Photonic Doppler Velocimetry (PDV) systems because PDV often yields incomplete information when lateral velocity components are present, or when there are drop-outs in the signal amplitude. In these cases, integration of the velocity from PDV can give incorrect displacement results. Experiments are now regularly fielded with over 100 channels of PDV, and BLR is being developed in a modular way to enable high channel counts of BLR and PDV recorded from the same probes pointed at the same target location. In this way instruments, will independently record surface velocity and distance information along the exact same path.

  2. Control of the polarization of attosecond pulses using a two-color field

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Camilo; Hoffmann, David J; Torres, Ricardo; Chipperfield, Luke E; Marangos, Jonathan P [Blackett Laboratory, Imperial College London, London SW7 2BW (United Kingdom)], E-mail: camilo@usal.es

    2009-11-15

    Control over the polarization of an attosecond pulse train (APT) is demonstrated theoretically using orthogonally polarized two-color fields. The carrier envelope phase of the two pulses is used as a control parameter to generate both an APT with linear polarization in two nearly perpendicular planes or a train of elliptically polarized pulses of alternating helicity. By using few-cycle driving laser fields an isolated attosecond pulse with elliptical polarization is shown to be generated after selecting the cut-off region of the harmonic spectrum. The control mechanism is explained in terms of classical trajectories.

  3. Spatial properties of a terahertz beam generated from a two-color air plasma

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Wang, Tianwu; Buron, Jonas Christian Due

    2013-01-01

    We present a spatial characterization of terahertz (THz) beams generated from a two-color air plasma under different conditions by measuring full 3D beam profiles using a commercial THz camera. We compare two THz beam profiles emitted from plasmas generated by 35 fs and 100 fs laser pulses......, and show that the spatial properties of the two THz beams do not change significantly. For the THz beam profile generated by the 35 fs pulse, the spatial effect of eliminating the lower frequencies is investigated by implementing two crossed polarizers working as a high-pass filter. We show...

  4. Two-color resonance photoionization spectrum of nickelocene in a supersonic jet

    Science.gov (United States)

    Ketkov, S. Yu.; Selzle, H. L.; Schlag, E. W.; Titova, S. N.; Kalakutskaya, L. V.

    2004-10-01

    Two-color photoionization of nickelocene molecules cooled in a supersonic jet is performed using a tunable nanosecond pulsed laser. The first stage of the multiphoton excitation is the transition from the highest occupied molecular orbital of nickelocene to the lowest Rydberg level. Conditions are found under which molecular ions (η 5-C5H5)2Ni+ are the only product of the multiphoton ionization in the one-color experiment. Irradiation of an excited molecule by an intense pulse of another laser increases significantly the yield of molecular ions. The dependence of the yield of (η5-C5H5)2Ni+ ions on the frequency of the second laser makes it possible to determine the adiabatic ionization potential of nickelocene as 6.138±0.012eV.

  5. Theoretical analysis and numerical solution of laser pulse transformation for satellite laser ranging

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The processes of the pulse transformation in satellite laser ranging (SLR) are analyzed,the analytical expressions of the transformation are deduced,and the effects of the transformation on Center-of-Mass corrections of satellite and ranging precision are discussed.The numerical solution of the transformation and its effects are also given.The results reveal the rules of pulse transformation affected by different kinds of factors.These are significant for designing the SLR system with millimeter accuracy.

  6. Infrared Lunar Laser Ranging at Calern : Impact on Lunar Dynamics

    Science.gov (United States)

    Viswanathan, Vishnu; Fienga, Agnes; Manche, Herve; Gastineau, Mickael; Courde, Clement; Torre, Jean Marie; Exertier, Pierre; Laskar, Jacques

    2017-04-01

    Introduction: Since 2015, in addition to the traditional green (532nm), infrared (1064nm) has been the preferred wavelength for lunar laser ranging at the Calern lunar laser ranging (LLR) site in France. Due to the better atmospheric transmission of IR with respect to Green, nearly 3 times the number of normal points have been obtained in IR than in Green [1]. Dataset: In our study, in addition to the historical data obtained from various other LLR sites, we include the recent IR normal points obtained from Calern over the 1 year time span (2015-2016), constituting about 4.2% of data spread over 46 years of LLR. Near even distribution of data provided by IR on both the spatial and temporal domain, helps us to improve constraints on the internal structure of the Moon modeled within the planetary ephemeris : INPOP [2]. Data reduction: IERS recommended models have been used in the data reduction software GINS (GRGS,CNES) [3]. Constraints provided by GRAIL [4], on the Lunar gravitational potential and Love numbers have been taken into account in the least-square fit procedure. Earth orientation parameters from KEOF series have been used as per a recent study [5]. Results: New estimates on the dynamical parameters of the lunar core will be presented. Acknowledgements: We thank the lunar laser ranging observers at Observatoire de la Côte d'Azur, France, McDonald Observatory, Texas, Haleakala Observatory, Hawaii, and Apache Point Observatory in New Mexico for providing LLR observations that made this study possible. The research described in this abstract was carried out at Geoazur-CNRS, France, as a part of a PhD thesis funded by Observatoire de Paris and French Ministry of Education and Research. References: [1] Clement C. et al. (2016) submitted to A&A [2] Fienga A. et al. (2015) Celest Mech Dyn Astr, 123: 325. doi:10.1007/s10569-015-9639-y [3] Viswanathan V. et al. (2015) EGU, Abstract 18, 13995 [4] Konopliv A. S. et al. (2013) J. Geophys. Res. Planets, 118, 1415

  7. Probing Gravity with Next Generation Lunar Laser Ranging

    Science.gov (United States)

    Martini, Manuele; Dell'Agnello, Simone

    Lunar and satellite laser ranging (LLR/SLR) are consolidated techniques which provide a precise, and at the same time, cost-effective method to determine the orbits of the Moon and of satellites equipped with laser retroreflectors with respect to the International Celestial Reference System. We describe the precision tests of general relativity and of new theories of gravity that can be performed with second-generation LLR payloads on the surface of the Moon (NASA/ASI MoonLIGHT project), and with SLR/LLR payloads deployed on spacecraft in the Earth-Moon system. A new wave of lunar exploration and lunar science started in 2007-2008 with the launch of three missions (Chang'e by China, Kaguya by Japan, Chandrayaan by India), missions in preparation (LCROSS, LRO, GRAIL/LADEE by NASA) and other proposed missions (like MAGIA in Italy). This research activity will be greatly enhanced by the future robotic deployment of a lunar geophysics network (LGN) on the surface of the Moon. A scientific concept of the latter is the International Lunar Network (ILN, see http://iln.arc.nasa.gov/). The LLR retroreflector payload developed by a US-Italy team described here and under space qualification at the National Laboratories of Frascati (LNF) is the optimum candidate for the LGN, which will be populated in the future by any lunar landing mission.

  8. Nuclear Gamma-Ray Laser of Optical Range

    CERN Document Server

    Tkalya, E V

    2010-01-01

    A possibility of amplification of the 7.6 eV (3.5 eV) $\\gamma$-radiation by the stimulated $\\gamma$-emission of the ensemble of the $^{229m}$Th isomeric nuclei in a host dielectric crystal with a large band gap is proved theoretically. This amplification is a result of the following three factors: 1) the excitation of a great number of the $^{229m}$Th isomers by laser radiation; 2) the creation of the inverse population of nuclear levels in a cooled sample placed in magnetic field; 3) the emissions/absorption of the optical photons by thorium nuclei in the crystal without recoil (the M\\"{o}ssbauer effect in the optical range).

  9. Upgrading NASA/DOSE laser ranging system control computers

    Science.gov (United States)

    Ricklefs, Randall L.; Cheek, Jack; Seery, Paul J.; Emenheiser, Kenneth S.; Hanrahan, William P., III; Mcgarry, Jan F.

    1993-01-01

    Laser ranging systems now managed by the NASA Dynamics of the Solid Earth (DOSE) and operated by the Bendix Field Engineering Corporation, the University of Hawaii, and the University of Texas have produced a wealth on interdisciplinary scientific data over the last three decades. Despite upgrades to the most of the ranging station subsystems, the control computers remain a mix of 1970's vintage minicomputers. These encompass a wide range of vendors, operating systems, and languages, making hardware and software support increasingly difficult. Current technology allows replacement of controller computers at a relatively low cost while maintaining excellent processing power and a friendly operating environment. The new controller systems are now being designed using IBM-PC-compatible 80486-based microcomputers, a real-time Unix operating system (LynxOS), and X-windows/Motif IB, and serial interfaces have been chosen. This design supports minimizing short and long term costs by relying on proven standards for both hardware and software components. Currently, the project is in the design and prototyping stage with the first systems targeted for production in mid-1993.

  10. Testing Gravity via Lunar Laser Ranging: Maximizing Data Quality

    Science.gov (United States)

    Murphy, Thomas

    We propose to continue leading-edge observations with the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO), in an effort to subject gravity to the most stringent tests yet. APOLLO has delivered a dramatic improvement in the measurement of the lunar orbit: now at the millimeter level. Yet incomplete models are thus far unable to confirm the accuracy. We therefore seek to build a calibration system to ensure that APOLLO meets its millimeter measurement goal. Gravity--the most evident force of nature--is in fact the weakest of the fundamental forces, and consequently the most poorly tested. Einstein’s general relativity, which is currently our best description of gravity, is fundamentally incompatible with quantum mechanics and is likely to be replaced by a more complete theory in the future. A modified theory would predict small deviations in the solar system that could have profound consequences for our understanding of the Universe as a whole. Lunar laser ranging (LLR), in which short laser pulses launched from a telescope are bounced off of reflectors placed on the Moon by U.S. astronauts and Soviet landers, has for decades produced some of the leading tests of gravity by mapping the shape of the lunar orbit to high precision. These include tests of the strong equivalence principle, the time-rate-ofchange of Newton’s gravitational constant, gravitomagnetism, the inverse-square law, and many others. Among the attributes that contribute to APOLLO’s superior observations, routine ranging to all five lunar reflectors on timescales of minutes dramatically improves our ability to gauge lunar orientation and body distortion. This information produces insights into the interior structure and dynamics of the Moon, allowing a more precise determination of the path for the Moon’s center of mass, lending to tests of fundamental gravity. Simultaneously, higher precision range measurements, together with data from a superconducting gravimeter at the

  11. Tectonic motion and deformation from satellite laser ranging to Lageos

    Science.gov (United States)

    Smith, David E.; Kolenkiewicz, Ronald; Dunn, Peter J.; Robbins, John W.; Torrence, Mark H.; Klosko, Steve M.; Williamson, Ronald G.; Pavlis, Erricos C.; Douglas, Nancy B.

    1990-01-01

    Data on satellite laser ranging (SLR) to Lageos aquired during the period 1978-1988 are analyzed on the basis of the precise modeling of the orbit dynamics of Lageos, producing estimates of tectonic motion for 22 sites located on seven major plates. It was estimated that intraplate motion within northern Europe is below the 2 mm/yr level in absolute rate, in agreement with conclusions of Zoback et al. (1989) regarding the stress across the region. A comparison of SLR geodesic rates with those from NUVEL-1 and AMO-2 models showed high correlations between tracking sites that are well within plate interiors, but displayed small but significant departures from unity in slope which are attributed to the possibility of recent changes in relative velocities or geologic time scale uncertainties. For lines crossing the Nnorth Atlantic, the San Andreas fault, and within the Basin and Range province, the geodesic rates determined by SLR are in good agreement with those determined by VLBI.

  12. Determination of crustal motions using satellite laser ranging

    Science.gov (United States)

    1991-01-01

    Satellite laser ranging has matured over the last decade into one of the essential space geodesy techniques. It has demonstrated centimeter site positioning and millimeter per year velocity determinations in a frame tied dynamically to the mass center of the solid Earth hydrosphere atmosphere system. Such a coordinate system is a requirement for studying long term eustatic sea level rise and other global change phenomena. Earth orientation parameters determined with the coordinate system have been produced in near real time operationally since 1983, at a relatively modest cost. The SLR ranging to Lageos has also provided a rich spectrum of results based upon the analysis of Lageos orbital dynamics. These include significant improvements in the knowledge of the mean and variable components of the Earth's gravity field and the Earth's gravitational parameter. The ability to measure the time variations of the Earth's gravity field has opened as exciting area of study in relating global processes, including meteorologically derived mass transport through changes in the satellite dynamics. New confirmation of general relativity was obtained using the Lageos SLR data.

  13. Laser speckle reduction by phase range limited computer generated hologram in laser projection display system.

    Science.gov (United States)

    Chang, Yan-Shuo; Lin, Chia-Hsin; Hsu, Ku-Hui; Hsu, Wei-Feng; Hsiao, Li-Jen; Lin, Hoang Yan

    2014-09-20

    The speckle phenomenon is an annoyance in laser projection display systems. We propose a novel speckle suppression method that utilizes the interference concept on a pixel point, which reduces the speckle contrast (SC) of the project image by limiting the phase distribution range in the optical field. The SC formula is derived in the uniform interval phase range for partially developed speckle conditions, showing that the SC can be lowered by lessening the phase range limitation. In the ideal simulation model, the SC can be reduced from 98.77% to 0% as the phase range limitation varies from 2π to 0. The phase range limitation model is a novel method using a computer generated hologram to provide beam shaping and phase limitation. In a more realistic simulation model, the SC is reduced from 99.18% to 16.68%.

  14. Short-Range Sensor for Underwater Robot Navigation using Line-lasers and Vision

    DEFF Research Database (Denmark)

    Hansen, Peter Nicholas; Nielsen, Mikkel Cornelius; Christensen, David Johan

    2015-01-01

    This paper investigates a minimalistic laser-based range sensor, used for underwater inspection by Autonomous Underwater Vehicles (AUV). This range detection system system comprise two lasers projecting vertical lines, parallel to a camera’s viewing axis, into the environment. Using both lasers...

  15. Short-Range Sensor for Underwater Robot Navigation using Line-lasers and Vision

    DEFF Research Database (Denmark)

    Hansen, Peter Nicholas; Nielsen, Mikkel Cornelius; Christensen, David Johan;

    2015-01-01

    This paper investigates a minimalistic laser-based range sensor, used for underwater inspection by Autonomous Underwater Vehicles (AUV). This range detection system system comprise two lasers projecting vertical lines, parallel to a camera’s viewing axis, into the environment. Using both lasers f...

  16. A Lunar Laser Ranging Retroreflector for the 21st Century

    Science.gov (United States)

    Currie, D.; Dell-Agnello, S.; Delle Monache, G.

    Over the past forty years, Lunar Laser Ranging (LLR) to the Apollo Cube Corner (CCR) Retroreflector arrays has supplied almost all of the significant tests of General Relativity. The LLR program has evaluated the PPN parameters and addressed, for example, the possible change in the gravitational constant and the properties of the self-energy of the gravitational field. In addition, LLR has provided significant information on the composition and origin of the moon. These arrays are the only experiment of the Apollo program that are still in operation. Initially the Apollo Lunar Arrays contributed a negligible portion of the error budget used to achieve these results. Over the decades, the performance of ground stations has greatly upgraded so that the ranging accuracy has improved by more than two orders of magnitude, i.e., a factor of 140. Now, after forty years, because of the lunar librations the existing Apollo retroreflector arrays contribute significant fraction of the limiting errors in the range measurements. The University of Maryland, as the Principal Investigator for the original Apollo arrays, is now proposing a new approach to the Lunar Laser CCR array technology. The investigation of this new technology, with Professor Currie as Principal Investigator, is currently being supported by two NASA programs and, in part, also by INFN/LNF. Thus after the proposed installation on the next Lunar landing, the new arrays will support ranging observations that are a factor 100 more accurate than the current Apollo LLRRAs, from the centimeter level to the micron level. The new fundamental physics and the lunar physics that this new LLRRA can provide will be described. In the design of the new array, there are three major challenges: 1) Validate that the specifications of the CCR required for the new array, with are significantly beyond the properties of current CCRs, can indeed be achieved. 2) Address the thermal and optical effects of the absorption of solar

  17. MATILDA: A Military Laser Range Safety Tool Based on Probabilistic Risk Assessment (PRA) Techniques

    Science.gov (United States)

    2014-08-01

    AFRL-RH-FS-TR-2014-0035 MATILDA: A Military Laser Range Safety Tool Based on Probabilistic Risk Assessment (PRA) Techniques Paul...the Government’s approval or disapproval of its ideas or findings. MATILDA: A Military Laser Range Safety Tool Based on Probabilistic Risk Assessment... Probabilistic Risk Assessment (PRA) techniques to perform laser safety and hazard analysis for high output lasers in outdoor environments has become

  18. Contribution of satellite laser ranging to combined gravity field models

    Science.gov (United States)

    Maier, A.; Krauss, S.; Hausleitner, W.; Baur, O.

    2012-02-01

    In the framework of satellite-only gravity field modeling, satellite laser ranging (SLR) data is typically exploited to recover long-wavelength features. This contribution provides a detailed discussion of the SLR component of GOCO02S, the latest release of combined models within the GOCO series. Over a period of five years (January 2006 to December 2010), observations to LAGEOS-1, LAGEOS-2, Ajisai, Stella, and Starlette were analyzed. We conducted a series of closed-loop simulations and found that estimating monthly sets of spherical harmonic coefficients beyond degree five leads to exceedingly ill-posed normal equation systems. Therefore, we adopted degree five as the spectral resolution for real data analysis. We compared our monthly coefficient estimates of degree two with SLR and Gravity Recovery and Climate Experiment (GRACE) time series provided by the Center for Space Research (CSR) at Austin, Texas. Significant deviations in C20 were noted between SLR and GRACE; the agreement is better for the non-zonal coefficients. Fitting sinusoids together with a linear trend to our C20 time series yielded a rate of (-1.75 ± 0.6) × 10-11/yr; this drift is equivalent to a geoid change from pole to equator of 0.35 ± 0.12 mm/yr or an apparent Greenland mass loss of 178.5 ± 61.2 km3/yr. The mean of all monthly solutions, averaged over the five-year period, served as input for the satellite-only model GOCO02S. The contribution of SLR to the combined gravity field model is highest for C20, and hence is essential for the determination of the Earth's oblateness.

  19. Bore-Sight Calibration of Multiple Laser Range Finders for Kinematic 3D Laser Scanning Systems

    Directory of Open Access Journals (Sweden)

    Jaehoon Jung

    2015-05-01

    Full Text Available The Simultaneous Localization and Mapping (SLAM technique has been used for autonomous navigation of mobile systems; now, its applications have been extended to 3D data acquisition of indoor environments. In order to reconstruct 3D scenes of indoor space, the kinematic 3D laser scanning system, developed herein, carries three laser range finders (LRFs: one is mounted horizontally for system-position correction and the other two are mounted vertically to collect 3D point-cloud data of the surrounding environment along the system’s trajectory. However, the kinematic laser scanning results can be impaired by errors resulting from sensor misalignment. In the present study, the bore-sight calibration of multiple LRF sensors was performed using a specially designed double-deck calibration facility, which is composed of two half-circle-shaped aluminum frames. Moreover, in order to automatically achieve point-to-point correspondences between a scan point and the target center, a V-shaped target was designed as well. The bore-sight calibration parameters were estimated by a constrained least squares method, which iteratively minimizes the weighted sum of squares of residuals while constraining some highly-correlated parameters. The calibration performance was analyzed by means of a correlation matrix. After calibration, the visual inspection of mapped data and residual calculation confirmed the effectiveness of the proposed calibration approach.

  20. Metrology Camera System Using Two-Color Interferometry

    Science.gov (United States)

    Dubovitsky, Serge; Liebe, Carl Christian; Peters, Robert; Lay, Oliver

    2007-01-01

    A metrology system that contains no moving parts simultaneously measures the bearings and ranges of multiple reflective targets in its vicinity, enabling determination of the three-dimensional (3D) positions of the targets with submillimeter accuracy. The system combines a direction-measuring metrology camera and an interferometric range-finding subsystem. Because the system is based partly on a prior instrument denoted the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor and because of its 3D capability, the system is denoted the MSTAR3D. Developed for use in measuring the shape (for the purpose of compensating for distortion) of large structures like radar antennas, it can also be used to measure positions of multiple targets in the course of conventional terrestrial surveying. A diagram of the system is shown in the figure. One of the targets is a reference target having a known, constant distance with respect to the system. The system comprises a laser for generating local and target beams at a carrier frequency; a frequency shifting unit to introduce a frequency shift offset between the target and local beams; a pair of high-speed modulators that apply modulation to the carrier frequency in the local and target beams to produce a series of modulation sidebands, the highspeed modulators having modulation frequencies of FL and FM; a target beam launcher that illuminates the targets with the target beam; optics and a multipixel photodetector; a local beam launcher that launches the local beam towards the multi-pixel photodetector; a mirror for projecting to the optics a portion of the target beam reflected from the targets, the optics being configured to focus the portion of the target beam at the multi-pixel photodetector; and a signal-processing unit connected to the photodetector. The portion of the target beam reflected from the targets produces spots on the multi-pixel photodetector corresponding to the targets, respectively, and the signal

  1. Test technology on divergence angle of laser range finder based on CCD imaging fusion

    Science.gov (United States)

    Shi, Sheng-bing; Chen, Zhen-xing; Lv, Yao

    2016-09-01

    Laser range finder has been equipped with all kinds of weapons, such as tank, ship, plane and so on, is important component of fire control system. Divergence angle is important performance and incarnation of horizontal resolving power for laser range finder, is necessary appraised test item in appraisal test. In this paper, based on high accuracy test on divergence angle of laser range finder, divergence angle test system is designed based on CCD imaging, divergence angle of laser range finder is acquired through fusion technology for different attenuation imaging, problem that CCD characteristic influences divergence angle test is solved.

  2. Receiver Design, Performance Analysis, and Evaluation for Space-Borne Laser Altimeters and Space-to-Space Laser Ranging Systems

    Science.gov (United States)

    Davidson, Frederic M.; Sun, Xiaoli; Field, Christopher T.

    1996-01-01

    This progress report consists of two separate reports. The first one describes our work on the use of variable gain amplifiers to increase the receiver dynamic range of space borne laser altimeters such as NASA's Geoscience Laser Altimeter Systems (GLAS). The requirement of the receiver dynamic range was first calculated. A breadboard variable gain amplifier circuit was made and the performance was fully characterized. The circuit will also be tested in flight on board the Shuttle Laser Altimeter (SLA-02) next year. The second report describes our research on the master clock oscillator frequency calibration for space borne laser altimeter systems using global positioning system (GPS) receivers.

  3. Simultaneous Laser Ranging and Communication from an Earth-Based Satellite Laser Ranging Station to the Lunar Reconnaissance Orbiter in Lunar Orbit

    Science.gov (United States)

    Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Neumann, Gregory A.; McIntire, Leva; Zellar, Ronald S.; Davidson, Frederic M.; Fong, Wai H.; Krainak, Michael A.; Zuber, Maria T.; Smith, David E.

    2013-01-01

    We report a free space laser communication experiment from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit through the on board one-way Laser Ranging (LR) receiver. Pseudo random data and sample image files were transmitted to LRO using a 4096-ary pulse position modulation (PPM) signal format. Reed-Solomon forward error correction codes were used to achieve error free data transmission at a moderate coding overhead rate. The signal fading due to the atmosphere effect was measured and the coding gain could be estimated.

  4. The 1.06 optical receiver. [avalanche photodiodes for laser range finders

    Science.gov (United States)

    Tomasetta, L. R.; Law, H. D.; Nakano, K.; Scholl, F. W.; Harris, J. S., Jr.

    1978-01-01

    High performance 1.06 micron m avalanche photodetectors (APDs), fabricated in the GaAlSb system, have high quantum efficiency (90 percent), high speed (risetime less than 60 ps) and low leakage currents (less than 50 na). The dark current represents more than an order of magnitude reduction compared to previously reported results. The high speed avalanche gain of these devices is between 20 and 50. The area uniformity is better than + or - 10 percent. GaAlAs APDs at 0.53 micron m have even faster speed, lower dark currents, and high speed gains of 100 to 200. Optical rangefinders based on measured APD performance parameters have far superior performance when compared to even ideal photomultiplier tubes in either a one color or two color rangefinder system. For a one color system, f factor of two lower time jitter can be achieved with identical transmitted power. The superiority of the APD based two color receiver is significant and exists in the entire range of desired time jitters (less than 100 ps) and received power levels.

  5. Enhanced harmonic generation and wave-mixing via two-color multiphoton excitation of atoms/molecules

    CERN Document Server

    Avetissian, H K; Mkrtchian, G F

    2016-01-01

    We consider harmonics generation and wave-mixing by two-color multi photon resonant excitation of three-level atoms/molecules in strong laser fields. The coherent part of the spectra corresponding to multicolor harmonics generation is investigated. The obtained analytical results on the basis of generalized rotating wave approximation are in a good agreement with numerical calculations. The results applied to the hydrogen atom and homonuclear diatomic molecular ion show that one can achieve efficient generation of moderately high multicolor harmonics via multiphoton resonant excitation by appropriate laser pulses.

  6. Constaints on Lorentz symmetry violations using lunar laser ranging observations

    Science.gov (United States)

    Bourgoin, Adrien

    2016-12-01

    General Relativity (GR) and the standard model of particle physics provide a comprehensive description of the four interactions of nature. A quantum gravity theory is expected to merge these two pillars of modern physics. From unification theories, such a combination would lead to a breaking of fundamental symmetry appearing in both GR and the standard model of particle physics as the Lorentz symmetry. Lorentz symmetry violations in all fields of physics can be parametrized by an effective field theory framework called the standard-model extension (SME). Local Lorentz Invariance violations in the gravitational sector should impact the orbital motion of bodies inside the solar system, such as the Moon. Thus, the accurate lunar laser ranging (LLR) data can be analyzed in order to study precisely the lunar motion to look for irregularities. For this purpose, ELPN (Ephéméride Lunaire Parisienne Numérique), a new lunar ephemeris has been integrated in the SME framework. This new numerical solution of the lunar motion provides time series dated in temps dynamique barycentrique (TDB). Among that series, we mention the barycentric position and velocity of the Earth-Moon vector, the lunar libration angles, the time scale difference between the terrestrial time and TDB and partial derivatives integrated from variational equations. ELPN predictions have been used to analyzed LLR observations. In the GR framework, the residuals standard deviations has turned out to be the same order of magnitude compare to those of INPOP13b and DE430 ephemerides. In the framework of the minimal SME, LLR data analysis provided constraints on local Lorentz invariance violations. Spetial attention was paid to analyze uncertainties to provide the most realistic constraints. Therefore, in a first place, linear combinations of SME coefficients have been derived and fitted to LLR observations. In a second time, realistic uncertainties have been determined with a resampling method. LLR data

  7. Two-color lattice QCD with staggered quarks

    Energy Technology Data Exchange (ETDEWEB)

    Scheffler, David

    2015-07-20

    The study of quantum chromodynamics (QCD) at finite temperature and density provides important contributions to the understanding of strong-interaction matter as it is present e.g. in nuclear matter and in neutron stars or as produced in heavy-ion collision experiments. Lattice QCD is a non-perturbative approach, where equations of motion for quarks and gluons are discretized on a finite space-time lattice. The method successfully describes the behavior of QCD in the vacuum and at finite temperature, however it cannot be applied to finite baryon density due to the fermion sign problem. Various QCD-like theories, that offer to draw conclusions about QCD, allow simulations also at finite densities. In this work we investigate two-color QCD as a popular example of a QCD-like theory free from the sign problem with methods from lattice gauge theory. For the generation of gauge configurations with two dynamical quark flavors in the staggered formalism with the ''rooting trick'' we apply the Rational Hybrid Monte Carlo (RHMC) algorithm. We carry out essential preparatory work for future simulations at finite density. As a start, we concentrate on the calculation of the effective potential for the Polyakov loop, which is an order parameter for the confinement-deconfinement transition, in dependence of the temperature and quark mass. It serves as an important input for effective models of QCD. We obtain the effective potential via the histogram method from local distributions of the Polyakov loop. To study the influence of dynamical quarks on gluonic observables, the simulations are performed with large quark masses and are compared to calculations in the pure gauge theory. In the second part of the thesis we examine aspects of the chiral phase transition along the temperature axis. The symmetry group of chiral symmetry in two-color QCD is enlarged to SU(2N{sub f}). Discretized two-color QCD in the staggered formalism exhibits a chiral symmetry breaking

  8. Assessing probe-specific dye and slide biases in two-color microarray data

    Directory of Open Access Journals (Sweden)

    Goldberg Zelanna

    2008-07-01

    Full Text Available Abstract Background A primary reason for using two-color microarrays is that the use of two samples labeled with different dyes on the same slide, that bind to probes on the same spot, is supposed to adjust for many factors that introduce noise and errors into the analysis. Most users assume that any differences between the dyes can be adjusted out by standard methods of normalization, so that measures such as log ratios on the same slide are reliable measures of comparative expression. However, even after the normalization, there are still probe specific dye and slide variation among the data. We define a method to quantify the amount of the dye-by-probe and slide-by-probe interaction. This serves as a diagnostic, both visual and numeric, of the existence of probe-specific dye bias. We show how this improved the performance of two-color array analysis for arrays for genomic analysis of biological samples ranging from rice to human tissue. Results We develop a procedure for quantifying the extent of probe-specific dye and slide bias in two-color microarrays. The primary output is a graphical diagnostic of the extent of the bias which called ECDF (Empirical Cumulative Distribution Function, though numerical results are also obtained. Conclusion We show that the dye and slide biases were high for human and rice genomic arrays in two gene expression facilities, even after the standard intensity-based normalization, and describe how this diagnostic allowed the problems causing the probe-specific bias to be addressed, and resulted in important improvements in performance. The R package LMGene which contains the method described in this paper has been available to download from Bioconductor.

  9. A Detailed Evaluation of a Laser Triangulation Ranging System for Mobile Robots

    Science.gov (United States)

    1983-08-01

    A RPI TECHNICAL REPORT MP-82 A DETAILED EVALUATION OF A LASER - TRIANGULATION RANGING SYSTEM FOR MOBILE ROBOTS by Thomas J. Clement Contract MDA-903...Polytechnic Institute Technical Report MP-79, Troy, N.Y., May 1982. 9. McNellis, T., "Evaluation of a Laser Triangulation Ranging System for Mobile Robots ." Rensselaer

  10. Noise in two-color electronic distance meter measurements revisited

    Science.gov (United States)

    Langbein, J.

    2004-01-01

    Frequent, high-precision geodetic data have temporally correlated errors. Temporal correlations directly affect both the estimate of rate and its standard error; the rate of deformation is a key product from geodetic measurements made in tectonically active areas. Various models of temporally correlated errors are developed and these provide relations between the power spectral density and the data covariance matrix. These relations are applied to two-color electronic distance meter (EDM) measurements made frequently in California over the past 15-20 years. Previous analysis indicated that these data have significant random walk error. Analysis using the noise models developed here indicates that the random walk model is valid for about 30% of the data. A second 30% of the data can be better modeled with power law noise with a spectral index between 1 and 2, while another 30% of the data can be modeled with a combination of band-pass-filtered plus random walk noise. The remaining 10% of the data can be best modeled as a combination of band-pass-filtered plus power law noise. This band-pass-filtered noise is a product of an annual cycle that leaks into adjacent frequency bands. For time spans of more than 1 year these more complex noise models indicate that the precision in rate estimates is better than that inferred by just the simpler, random walk model of noise.

  11. Towards the phase diagram of dense two-color matter

    CERN Document Server

    Cotter, Seamus; Hands, Simon; Skullerud, Jon-Ivar

    2012-01-01

    We study two-color QCD with two flavors of Wilson fermion as a function of quark chemical potential mu and temperature T. We find evidence of a superfluid phase at intermediate mu and low T where the quark number density and diquark condensate are both very well described by a Fermi sphere of nearly-free quarks disrupted by a BCS condensate. Our results suggest that the quark contribution to the energy density is negative (and balanced by a positive gauge contribution), although this result is highly sensitive to details of the energy renormalisation. We also find evidence that the chiral condensate in this region vanishes in the massless limit. This region gives way to a region of deconfined quark matter at higher T and mu, with the deconfinement temperature, determined from the renormalised Polyakov loop, decreasing only very slowly with increasing chemical potential. The quark number susceptibility chi_q does not exhibit any qualitative change at the deconfinement transition. We argue that this is because ...

  12. Photofragmentation of colloidal solutions of gold nanoparticles under femtosecond laser pulses in IR and visible ranges

    Energy Technology Data Exchange (ETDEWEB)

    Danilov, P A; Zayarnyi, D A; Ionin, A A; Kudryashov, S I; Makarov, S V; Rudenko, A A; Saraeva, I N; Yurovskikh, V I [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Lednev, V N; Pershin, S M [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-05-31

    The specific features of photofragmentation of sols of gold nanoparticles under focused femtosecond laser pulses in IR (1030 nm) and visible (515 nm) ranges is experimentally investigated. A high photofragmentation efficiency of nanoparticles in the waist of a pulsed laser beam in the visible range (at moderate radiation scattering) is demonstrated; this efficiency is related to the excitation of plasmon resonance in nanoparticles on the blue shoulder of its spectrum, in contrast to the regime of very weak photofragmentation in an IR-laser field of comparable intensity. Possible mechanisms of femtosecond laser photofragmentation of gold nanoparticles are discussed. (extreme light fields and their applications)

  13. Benefits Derived From Laser Ranging Measurements for Orbit Determination of the GPS Satellite Orbit

    Science.gov (United States)

    Welch, Bryan W.

    2007-01-01

    While navigation systems for the determination of the orbit of the Global Position System (GPS) have proven to be very effective, the current research is examining methods to lower the error in the GPS satellite ephemerides below their current level. Two GPS satellites that are currently in orbit carry retro-reflectors onboard. One notion to reduce the error in the satellite ephemerides is to utilize the retro-reflectors via laser ranging measurements taken from multiple Earth ground stations. Analysis has been performed to determine the level of reduction in the semi-major axis covariance of the GPS satellites, when laser ranging measurements are supplemented to the radiometric station keeping, which the satellites undergo. Six ground tracking systems are studied to estimate the performance of the satellite. The first system is the baseline current system approach which provides pseudo-range and integrated Doppler measurements from six ground stations. The remaining five ground tracking systems utilize all measurements from the current system and laser ranging measurements from the additional ground stations utilized within those systems. Station locations for the additional ground sites were taken from a listing of laser ranging ground stations from the International Laser Ranging Service. Results show reductions in state covariance estimates when utilizing laser ranging measurements to solve for the satellite s position component of the state vector. Results also show dependency on the number of ground stations providing laser ranging measurements, orientation of the satellite to the ground stations, and the initial covariance of the satellite's state vector.

  14. A laser ranging system operating at 1036 nm with Geiger-mode silicon avalanche photodiode

    Science.gov (United States)

    Wu, Guang; Ren, Min; Liang, Yan; Wang, Zhiyuan; Pan, Haifeng; Zeng, Heping

    2012-09-01

    We demonstrated a laser ranging experiment obtained with a Geiger-mode silicon avalanche photodiode (Si GAPD). The Surface-to-surface resolution of 15 cm was achieved with the technique of time-correlated single-photon counting. In the experiment, a mode-locked Yb-doped fiber laser at 1036 nm was applied, as the detection efficiency at 1036 nm of Si GAPDs is much higher than that at 1064nm which was widely applied in remote sensing. Due to the single-photon detector, the laser ranging system was able to measure the reflected photon pulses at single-photon level. We realized 32- m laser ranging experiment with a 135-mm diameter Newtonian telescope in daylight. And the system could measure the non-cooperated object longer than 11.3 km far away, which was tested through inserting the optical loss. It presented a potential for hundreds-of-kilometer laser ranging at low-light level.

  15. Semiconductor lasers with a continuous tuning range above 100 nm in the nearest IR spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Kostin, Yu O; Lobintsov, A A; Shramenko, M V [OOO ' Opton' , Moscow (Russian Federation); Ladugin, M A; Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation); Chamorovsky, A Yu [Superlum Ltd., Unit B3, Fota Point Enterprise Park, Carrigtwohill, Co Cork (Ireland); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2015-08-31

    We have developed two new types of lasers based on quantum-confined semiconductor optical amplifiers with an acousto-optic tunable filter in an external fibre ring cavity. The lasers offer continuous wavelength tuning ranges from 780 to 885 and from 880 to 1010 nm, 20 mW of cw output power, and a tuning rate up to 10{sup 4} nm s{sup -1} at an instantaneous spectral linewidth less than 0.1 nm. (lasers)

  16. Improvement of range precision in laser detection and ranging system by using two Geiger mode avalanche photodiodes

    Science.gov (United States)

    Kim, Tae Hoon; Kong, Hong Jin; Jo, Sung Eun; Jeon, Byoung Goo; Oh, Min Seok; Heo, Ayoung; Park, Dong Jo

    2013-06-01

    In this paper, the improvement of range precision in a laser detection and ranging (LADAR) system by using two Geiger mode avalanche photodiodes (GmAPDs) is described. The LADAR system is implemented by using two GmAPDs with a beam splitter and applying comparative process to their ends. Then, the timing circuit receives the electrical signals only if each GmAPDs generates electrical signals simultaneously. Though this system decreases the energy of a laser-return pulse scattered from the target, it is effective in reducing the range precision. The experimental results showed that the average value of standard deviation of time of flights was improved from 61 mm to 37 mm when the pulse energy is 0.6 μJ. When the time bin width is 0.5 ns, the single-shot precision error of the LADAR system was also improved from 280 mm to 67 mm.

  17. Improvement of range precision in laser detection and ranging system by using two Geiger mode avalanche photodiodes.

    Science.gov (United States)

    Kim, Tae Hoon; Kong, Hong Jin; Jo, Sung Eun; Jeon, Byoung Goo; Oh, Min Seok; Heo, Ayoung; Park, Dong Jo

    2013-06-01

    In this paper, the improvement of range precision in a laser detection and ranging (LADAR) system by using two Geiger mode avalanche photodiodes (GmAPDs) is described. The LADAR system is implemented by using two GmAPDs with a beam splitter and applying comparative process to their ends. Then, the timing circuit receives the electrical signals only if each GmAPDs generates electrical signals simultaneously. Though this system decreases the energy of a laser-return pulse scattered from the target, it is effective in reducing the range precision. The experimental results showed that the average value of standard deviation of time of flights was improved from 61 mm to 37 mm when the pulse energy is 0.6 μJ. When the time bin width is 0.5 ns, the single-shot precision error of the LADAR system was also improved from 280 mm to 67 mm.

  18. Micron-Accurate Laser Fresnel-Diffraction Ranging System

    Science.gov (United States)

    Lehner, David; Campbell, Jonathan; Smith, Kelly; Sanders, Alvin; Allison, Stephen; Smaley, Larry

    2008-01-01

    Two versions of an optoelectronic system undergoing development are depicted. The system is expected to be capable of measuring a distance between 2 and 10 m with an error of no more than 1 micrometer. The system would be designed to exploit Fresnel diffraction of a laser beam. In particular, it would be designed to take advantage of the fact that a Fresnel diffraction pattern is ultrasensitive to distance. The two versions would differ in the following respects: In version 1, the focus of the telescope would be in the Fresnel region, and the telescope would have a small depth of focus. As a consequence, the Fresnel pattern would be imaged directly onto the photodetector array; in version 2, a multielement lens module would displace the Fresnel region from the vicinity of the pinhole to the vicinity of the optical receiver. As the distance to be measured varied, the location of the receiver relative to the displaced Fresnel-diffraction region would vary, thereby causing the Fresnel diffraction pattern on the focal plane to vary. The multielement lens module would also correct for aberrations. The processing of the digitized Fresnel diffraction pattern in the computer might be accelerated by using only parts of the pattern or even only one small part - the central pixel. As the distance from the pinhole increased, the central pixel would rapidly cycle between maximum and minimum light intensity. This in itself would not be sufficient to uniquely determine the distance. However, by varying the size of the pinhole or the wavelength of the laser, one could obtain a second cycle of variation of intensity that, in conjunction with the first cycle, could enable a unique determination of distance. Alternatively, for a single wavelength and a single pinhole size, it should suffice to consider the data from only two different key pixels in the Fresnel pattern.

  19. Application of Satellite Laser Ranging Techniques for Space Situational Awareness Efforts

    Science.gov (United States)

    Shappirio, M.; McGarry, J. F.; Bufton, J.; Cheek, J. W.; Coyle, D. B.; Hull, S. M.; Stysley, P. R.; Sun, X.; Young, R. P.; Zagwodzki, T.

    2016-09-01

    With the numbers of conjunction avoidance maneuvers for the International Space Station and other Low Earth Orbit satellites rising and likely to continue to increase, the need to develop methods to produce accurate 72+ hour orbital predictions is becoming critical. One emerging solution is to utilize satellite laser ranging techniques to range to debris and refine the initial positions to improve the orbital predictions for objects predicted to experience a close approach. Some stations in Europe have already demonstrated that this technique is possible, but it has not been employed to refine the likelihood of collision. We will present a notional architecture for laser ranging to debris utilizing existing satellite laser ranging or visual tracking facilities. We will also discuss the capabilities of laser ranging for Space Situational Awareness and provide a direct comparison to current visual and radar tracking methods.

  20. Design and simulation of a mixer and phase difference measuring circuitry for laser range finding systems

    Science.gov (United States)

    Liu, Guili; Wang, Yanlin; Liu, Gang

    2006-11-01

    This article focuses on the circuit implementation of a mixer and phase difference measurement for laser range finding systems. It will introduce simply the principle of the laser range finding system, which is the basis of the electronic circuitry design. The modulated laser lights of two different frequencies are mixed and the phase difference is detected in order to measure the range. The method of measuring the range is to use the mixer and the phase difference detector. The new and high precision IC that has a high quality makes the circuit simple and reliable. The circuit of the mixer and the phase difference detector for laser range finding systems is designed using AD608 and AD8302 chips.

  1. High Precision Ranging and Range-Rate Measurements over Free-Space-Laser Communication Link

    Science.gov (United States)

    Yang, Guangning; Lu, Wei; Krainak, Michael; Sun, Xiaoli

    2016-01-01

    We present a high-precision ranging and range-rate measurement system via an optical-ranging or combined ranging-communication link. A complete bench-top optical communication system was built. It included a ground terminal and a space terminal. Ranging and range rate tests were conducted in two configurations. In the communication configuration with 622 data rate, we achieved a two-way range-rate error of 2 microns/s, or a modified Allan deviation of 9 x 10 (exp -15) with 10 second averaging time. Ranging and range-rate as a function of Bit Error Rate of the communication link is reported. They are not sensitive to the link error rate. In the single-frequency amplitude modulation mode, we report a two-way range rate error of 0.8 microns/s, or a modified Allan deviation of 2.6 x 10 (exp -15) with 10 second averaging time. We identified the major noise sources in the current system as the transmitter modulation injected noise and receiver electronics generated noise. A new improved system will be constructed to further improve the system performance for both operating modes.

  2. Real-time high dynamic range laser scanning microscopy

    Science.gov (United States)

    Vinegoni, C.; Leon Swisher, C.; Fumene Feruglio, P.; Giedt, R. J.; Rousso, D. L.; Stapleton, S.; Weissleder, R.

    2016-04-01

    In conventional confocal/multiphoton fluorescence microscopy, images are typically acquired under ideal settings and after extensive optimization of parameters for a given structure or feature, often resulting in information loss from other image attributes. To overcome the problem of selective data display, we developed a new method that extends the imaging dynamic range in optical microscopy and improves the signal-to-noise ratio. Here we demonstrate how real-time and sequential high dynamic range microscopy facilitates automated three-dimensional neural segmentation. We address reconstruction and segmentation performance on samples with different size, anatomy and complexity. Finally, in vivo real-time high dynamic range imaging is also demonstrated, making the technique particularly relevant for longitudinal imaging in the presence of physiological motion and/or for quantification of in vivo fast tracer kinetics during functional imaging.

  3. Topographic laser ranging and scanning principles and processing

    CERN Document Server

    Shan, Jie

    2008-01-01

    A systematic, in-depth introduction to theories and principles of Light Detection and Ranging (LiDAR) technology is long overdue, as it is the most important geospatial data acquisition technology to be introduced in recent years. An advanced discussion, this text fills the void.Professionals in fields ranging from geology, geography and geoinformatics to physics, transportation, and law enforcement will benefit from this comprehensive discussion of topographic LiDAR principles, systems, data acquisition, and data processing techniques. The book covers ranging and scanning fundamentals, and broad, contemporary analysis of airborne LiDAR systems, as well as those situated on land and in space. The authors present data collection at the signal level in terms of waveforms and their properties; at the system level with regard to calibration and georeferencing; and at the data level to discuss error budget, quality control, and data organization. They devote the bulk of the book to LiDAR data processing and inform...

  4. Real-time high dynamic range laser scanning microscopy.

    Science.gov (United States)

    Vinegoni, C; Leon Swisher, C; Fumene Feruglio, P; Giedt, R J; Rousso, D L; Stapleton, S; Weissleder, R

    2016-04-01

    In conventional confocal/multiphoton fluorescence microscopy, images are typically acquired under ideal settings and after extensive optimization of parameters for a given structure or feature, often resulting in information loss from other image attributes. To overcome the problem of selective data display, we developed a new method that extends the imaging dynamic range in optical microscopy and improves the signal-to-noise ratio. Here we demonstrate how real-time and sequential high dynamic range microscopy facilitates automated three-dimensional neural segmentation. We address reconstruction and segmentation performance on samples with different size, anatomy and complexity. Finally, in vivo real-time high dynamic range imaging is also demonstrated, making the technique particularly relevant for longitudinal imaging in the presence of physiological motion and/or for quantification of in vivo fast tracer kinetics during functional imaging.

  5. Experiment of Diffuse Reflection Laser Ranging to Space Debris and Data Analysis

    CERN Document Server

    Sun, Hao; Zhang, ZhongPing; Wu, Bin

    2014-01-01

    Space debris has been posing a serious threat to human space activities and is needed to be measured and cataloged. As a new technology of space target surveillance, the measurement accuracy of DRLR (Diffuse Reflection Laser Ranging) is much higher than that of microwave radar and electro-optical measurement. Based on laser ranging data of space debris from DRLR system collected at SHAO (Shanghai Astronomical Observatory) in March-April 2013, the characteristics and precision of the laser ranging data are analyzed and its applications in OD (Orbit Determination) of space debris are discussed in this paper, which is implemented for the first time in China. The experiment indicates that the precision of laser ranging data can reach 39cm-228cm. When the data is sufficient enough (4 arcs of 3 days), the orbit accuracy of space debris can be up to 50m.

  6. A new bismuth-doped fibre laser, emitting in the range 1625 – 1775 nm

    Energy Technology Data Exchange (ETDEWEB)

    Dianov, E M; Firstov, S V; Alyshev, S V; Riumkin, K E; Shubin, A V; Medvedkov, O I; Mel' kumov, M A [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Khopin, V F; Gur' yanov, A N [G.G.Devyatykh Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2014-06-30

    CW lasing of a Bi-doped germanosilicate fibre in a wavelength range that covers the spectral region between the emission bands of Er and Tm fibre lasers has been demonstrated for the first time. (letters)

  7. Statistics of the residual refraction errors in laser ranging data

    Science.gov (United States)

    Gardner, C. S.

    1977-01-01

    A theoretical model for the range error covariance was derived by assuming that the residual refraction errors are due entirely to errors in the meteorological data which are used to calculate the atmospheric correction. The properties of the covariance function are illustrated by evaluating the theoretical model for the special case of a dense network of weather stations uniformly distributed within a circle.

  8. Two-color Photodetectors%双波段光电探测器

    Institute of Scientific and Technical Information of China (English)

    刘铁权; 但伟

    2000-01-01

    Photodetectors are the critical parts for implementation of optoelectoronic detection and various optoelectronic technology. The paper introduces two-color photodetectors made of silicon integrated with InGaAs. These photodetectors can detect and respond incident light with the range of 400~1 100 nm and 1 100~1 650 nm simultaneously.%光电探测器是实现光电检测及各种光电技术的核心部件。文章介绍采用Si和In-GaAs两种材料集成制作的双波段光电探测器,它能同时探测并区分400~1100nm和1100~1 650 nm波段的入射光。

  9. BEC-BCS crossover in a cold and magnetized two color NJL model

    CERN Document Server

    Duarte, Dyana C; Farias, R L S; Manso, Pedro H A; Ramos, Rudnei O; Scoccola, N N

    2016-01-01

    The BEC-BCS crossover for a NJL model with diquark interactions is studied in the presence of an external magnetic field. Particular attention is paid to different regularization schemes used in the literature. A thorough comparison of results is performed for the case of a cold and magnetized two-color NJL model. According to our results, the critical chemical potential for the BEC transition exhibits a clear inverse magnetic catalysis effect for magnetic fields in the range $ 1 \\lesssim eB/m_\\pi^2 \\lesssim 20 $. As for the BEC-BCS crossover, the corresponding critical chemical potential is very weakly sensitive to magnetic fields up to $eB \\sim 9\\ m_\\pi^2$, showing a much smaller inverse magnetic catalysis as compared to the BEC transition, and displays a strong magnetic catalysis from this point on.

  10. Design and observations of satellite laser ranging system for daylight tracking at Shanghai Observatory

    Institute of Scientific and Technical Information of China (English)

    杨福民; 肖炽昆; 陈婉珍; 张忠萍; 谭德同; 龚向东; 陈菊平; 黄力; 章建华

    1999-01-01

    The first satellite laser ranging system for daylight tracking in China was set up at Shanghai Observatory, Chinese Academy of Sciences. Both false alarm probability due to strong background noises and detection probability of the laser returns with single photon level from satellite in daylight for our system are analysed. The system design and performance characteristics of subsystems, adopted techniques and satellite ranging observations are given.

  11. Generation of picosecond laser pulses at 1030 nm with gigahertz range continuously tunable repetition rate.

    Science.gov (United States)

    Aubourg, Adrien; Lhermite, Jérôme; Hocquet, Steve; Cormier, Eric; Santarelli, Giorgio

    2015-12-01

    We report on a watt range laser system generating picosecond pulses using electro-optical modulation of a 1030 nm single frequency low noise laser diode. Its repetition rate is continuously tunable between 11 and 18 GHz. Over this range, output spectra and pulse characteristics are measured and compared with a numerical simulation. Finally, amplitude and residual phase noise measurements of the source are also presented.

  12. Realistic simulation of laser range finder behavior in a smoky environment

    OpenAIRE

    Formsma, O.; Dijkshoorn, N.; van Noort, S.; de Visser, A.

    2011-01-01

    The Urban Search and Rescue Simulation used for RoboCup lacks realistic response of laser range finders on smoke. In this paper, the behavior of a Hokuyo and Sick laser range finder in a smoky environment is studied. The behavior of the lasers is among others a function of the visibility level, and in this article this function is quantified into an explicit model. This model is implemented in a simulation environment which is the basis of the Virtual Robot competition of the RoboCup Rescue L...

  13. A Lunar Laser Ranging Retroreflector Array for the 21{sup st} Century

    Energy Technology Data Exchange (ETDEWEB)

    Currie, Douglas G. [Department of Physics, University of Maryland, College Park, MD 20742 (United States); NASA Lunar Science Institute, Moffett Field, CA 94089 US (United States); Dell' Agnello, Simone; Delle Monache, Giovanni O. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Frascati,I-00044 (Italy); Behr, Bradford [Department of Physics, University of Maryland, College Park, MD 20742 (United States); Williams, James G. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2013-10-15

    To date, lunar laser ranging to the Apollo retroreflector arrays, which are still operational after four decades, has produced some of the best tests of General Relativity. Since the ground Observatories have improved their accuracy by a factor of 200, the lunar hardware, due to the lunar librations, now limits the ranging accuracy. The Lunar Laser Ranging Retroreflector Array for the 21{sup st} Century program plans to deploy new packages that will improve the ranging accuracy by a factor of ten to one hundred in the next few years.

  14. Laser-ranging scanning system to observe topographical deformations of volcanoes.

    Science.gov (United States)

    Aoki, T; Takabe, M; Mizutani, K; Itabe, T

    1997-02-20

    We have developed a laser-ranging system to observe the topographical structure of volcanoes. This system can be used to measure the distance to a target by a laser and shows the three-dimensional topographical structure of a volcano with an accuracy of 30 cm. This accuracy is greater than that of a typical laser-ranging system that uses a corner-cube reflector as a target because the reflected light jitters as a result of inclination and unevenness of the target ground surface. However, this laser-ranging system is useful for detecting deformations of topographical features in which placement of a reflector is difficult, such as in volcanic regions.

  15. On Two Color and CCD Methods for the Determination of Astronomic Position.

    Science.gov (United States)

    1986-03-14

    INTRODUCTION .................................... 2 A. Astroposition Objectives As Related to Two-Color Refractometry .................. 2 B. Results...value for the astronomic longitude and latitude.-_ A. Astroposition Objectives As Related to Two-Color Refractometry The long term objectives consist...The interior of the box was divided into 4 bays containing the telescope, the refractometry optics, the power supplies and the refralctometry

  16. Fusing Range Measurements from Ultrasonic Beacons and a Laser Range Finder for Localization of a Mobile Robot

    Science.gov (United States)

    Ko, Nak Yong; Kuc, Tae-Yong

    2015-01-01

    This paper proposes a method for mobile robot localization in a partially unknown indoor environment. The method fuses two types of range measurements: the range from the robot to the beacons measured by ultrasonic sensors and the range from the robot to the walls surrounding the robot measured by a laser range finder (LRF). For the fusion, the unscented Kalman filter (UKF) is utilized. Because finding the Jacobian matrix is not feasible for range measurement using an LRF, UKF has an advantage in this situation over the extended KF. The locations of the beacons and range data from the beacons are available, whereas the correspondence of the range data to the beacon is not given. Therefore, the proposed method also deals with the problem of data association to determine which beacon corresponds to the given range data. The proposed approach is evaluated using different sets of design parameter values and is compared with the method that uses only an LRF or ultrasonic beacons. Comparative analysis shows that even though ultrasonic beacons are sparsely populated, have a large error and have a slow update rate, they improve the localization performance when fused with the LRF measurement. In addition, proper adjustment of the UKF design parameters is crucial for full utilization of the UKF approach for sensor fusion. This study contributes to the derivation of a UKF-based design methodology to fuse two exteroceptive measurements that are complementary to each other in localization. PMID:25970259

  17. Trajectory selection in high harmonic generation by controlling the phase between orthogonal two-color fields.

    Science.gov (United States)

    Brugnera, Leonardo; Hoffmann, David J; Siegel, Thomas; Frank, Felix; Zaïr, Amelle; Tisch, John W G; Marangos, Jonathan P

    2011-10-07

    We demonstrate control of short and long quantum trajectories in high harmonic emission through the use of an orthogonally polarized two-color field. By controlling the relative phase ϕ between the two fields we show via classical and quantum calculations that we can steer the two-dimensional trajectories to return, or not, to the core and so control the relative strength of the short or long quantum trajectory contribution. In experiments, we demonstrate that this leads to robust control over the trajectory contributions using a drive field from a femtosecond laser composed of the fundamental ω at 800 nm (intensity ∼1.2×10(14)  W cm(-2)) and its weaker orthogonally polarized second harmonic 2ω (intensity ∼0.3×10(14)  W cm(-2)) with the relative phase between the ω and 2ω fields varied simply by tilting a fused silica plate. This is the first demonstration of short and long quantum trajectory control at the single-atom level.

  18. Radiation damage free two-color X-ray ghost diffraction with atomic resolution

    CERN Document Server

    Li, Zheng; Chapman, Henry; Shih, Yanhua

    2015-01-01

    The X-ray free electron lasers (XFEL) can enable diffractive structural determination of protein crystals or single molecules that are too small and radiation-sensitive for conventional X-ray analysis. However the electronic form factor could have been modified during the ultrashort X-ray pulse due to photoionization and electron cascade caused by the intense X-ray pulse. For general X-ray imaging techniques, to minimize radiation damage effect is of major concern to ensure faithful reconstruction of the structure. Here we show that a radiation damage free diffraction can be achieved with an atomic spatial resolution, by using X-ray parametric down-conversion (PDC), and two-color biphoton ghost imaging. We illustrate that formation of the diffractive patterns satisfies a condition analogous to the Bragg equation, with a resolution that could be as fine as the lattice length scale of several Angstrom. Because the samples are illuminated by the optical photons of low energy, they can be free of radiation damage...

  19. Time-transfer experiments between satellite laser ranging ground stations via one-way laser ranging to the Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Mao, D.; Sun, X.; Skillman, D. R.; Mcgarry, J.; Hoffman, E.; Neumann, G. A.; Torrence, M. H.; Smith, D. E.; Zuber, M. T.

    2014-12-01

    Satellite laser ranging (SLR) has long been used to measure the distance from a ground station to an Earth-orbiting satellite in order to determine the spacecraft position in orbit, and to conduct other geodetic measurements such as plate motions. This technique can also be used to transfer time between the station and satellite, and between remote SLR sites, as recently demonstrated by the Time Transfer by Laser Link (T2L2) project by the Centre National d'Etudes Spatiaes (CNES) and Observatorire de la Cote d'Azur (OCA) as well as the Laser Time Transfer (LTT) project by the Shanghai Astronomical Observatory, where two-way and one-way measurements were obtained at the same time. Here we report a new technique to transfer time between distant SLR stations via simultaneous one-way laser ranging (LR) to the Lunar Reconnaissance Orbiter (LRO) spacecraft at lunar distance. The major objectives are to establish accurate ground station times and to improve LRO orbit determination via these measurements. The results of these simultaneous LR measurements are used to compare the SLR station times or transfer time from one to the other using times-of-flight estimated from conventional radio frequency tracking of LRO. The accuracy of the time transfer depends only on the difference of the times-of-flight from each ground station to the spacecraft, and is expected to be at sub-nano second level. The technique has been validated by both a ground-based experiment and an experiment that utilized LRO. Here we present the results to show that sub-nanosecond precision and accuracy are achievable. Both experiments were carried out between the primary LRO-LR station, The Next Generation Satellite Laser Ranging (NGSLR) station, and its nearby station, Mobile Laser System (MOBLAS-7), both at Greenbelt, Maryland. The laser transmit time from both stations were recorded by the same event timer referenced to a Hydrogen maser. The results have been compared to data from a common All

  20. Simulation of Far-Field Superresolution Fluorescence Imaging with Two-Color One-Photon Excitation of Reversible Photoactivatable Protein

    Institute of Scientific and Technical Information of China (English)

    WANG Chen; QIAO Ling-Ling; MAO Zheng-Le

    2011-01-01

    We propose to achieve far-field super-resolution imaging by using offset two-color one-photon (2C1P) excitation of reversible photoactivatable fluorescence proteins. Due to the distinctive photoswitching performance of the proteins, such as dronpa, the fluorescence emission will only come from the overlapped region of activation beam and excitation beam. The analysis solution of rate equation shows that the resolution of offset 2C1P microscope is "engineered" by laser power of excitation and activation beams and the power ratio between them. Superior lateral and transverse resolution is theoretically demonstrated compared with conventional fluorescence scanning microscopy.%@@ We propose to achieve far-field super-resolution imaging by using offset two-color one-photon(2C1P) excitation of reversible photoactivatable fluorescence proteins.Due to the distinctive photoswitching performance of the proteins,such as dronpa,the fluorescence emission will only come from the overlapped region of activation beam and excitation beam.The analysis solution of rate equation shows that the resolution of offset 2C1P microscope is "engineered" by laser power of excitation and activation beams and the power ratio between them.Superior lateral and transverse resolution is theoretically demonstrated compared with conventional fluorescence scanning microscopy.

  1. APOLLO: the Apache Point Observatory Lunar Laser-ranging Operation: Instrument Description and First Detections

    CERN Document Server

    Murphy, T W Jr; Battat, J B R; Carey, L N; Hoyle, C D; LeBlanc, P; Michelsen, E L; Nordtvedt, K; Orin, A E; Strasburg, J D; Stubbs, C W; Swanson, H E; Williams, E

    2007-01-01

    A next-generation lunar laser ranging apparatus using the 3.5 m telescope at the Apache Point Observatory in southern New Mexico has begun science operation. APOLLO (the Apache Point Observatory Lunar Laser-ranging Operation) has achieved one-millimeter range precision to the moon which should lead to approximately one-order-of-magnitude improvements in the precision of several tests of fundamental properties of gravity. We briefly motivate the scientific goals, and then give a detailed discussion of the APOLLO instrumentation.

  2. Identification of air and sea-surface targets with a laser range profiler

    NARCIS (Netherlands)

    Heuvel, J.C. van den; Schoemaker, R.M.; Schleijpen, H.M.A.

    2009-01-01

    Current coastal operations have to deal with threats at short range in complex environments with both neutral and hostile targets. There is a need for fast identification, which is possible with a laser range profiler. A number of field trials have been conducted to validate the concept of identific

  3. Identification of air and sea-surface targets with a laser range profiler

    NARCIS (Netherlands)

    Heuvel, J.C. van den; Schoemaker, R.M.; Schleijpen, H.M.A.

    2009-01-01

    Current coastal operations have to deal with threats at short range in complex environments with both neutral and hostile targets. There is a need for fast identification, which is possible with a laser range profiler. A number of field trials have been conducted to validate the concept of

  4. Characterisation of small targets in a maritime environment by means of laser range profiling

    NARCIS (Netherlands)

    Schoemaker, R.M.; Benoist, K.W.

    2011-01-01

    Potential asymmetric threats at short range in complex environments need to be identified quickly during coastal operations. Laser range profiling is a technology that has the potential to shorten the OODA loop (Orient, Observe, Detect, Act) by performing automatic characterisation of targets at

  5. Compensation for the distortion in satellite laser range predictions due to varying pulse travel times

    Science.gov (United States)

    Paunonen, Matti

    1993-01-01

    A method for compensating for the effect of the varying travel time of a transmitted laser pulse to a satellite is described. The 'observed minus predicted' range differences then appear to be linear, which makes data screening or use in range gating more effective.

  6. Two-color temporal focusing multiphoton excitation imaging with tunable-wavelength excitation

    Science.gov (United States)

    Lien, Chi-Hsiang; Abrigo, Gerald; Chen, Pei-Hsuan; Chien, Fan-Ching

    2017-02-01

    Wavelength tunable temporal focusing multiphoton excitation microscopy (TFMPEM) is conducted to visualize optical sectioning images of multiple fluorophore-labeled specimens through the optimal two-photon excitation (TPE) of each type of fluorophore. The tunable range of excitation wavelength was determined by the groove density of the grating, the diffraction angle, the focal length of lenses, and the shifting distance of the first lens in the beam expander. Based on a consideration of the trade-off between the tunable-wavelength range and axial resolution of temporal focusing multiphoton excitation imaging, the presented system demonstrated a tunable-wavelength range from 770 to 920 nm using a diffraction grating with groove density of 830 lines/mm. TPE fluorescence imaging examination of a fluorescent thin film indicated that the width of the axial confined excitation was 3.0±0.7 μm and the shifting distance of the temporal focal plane was less than 0.95 μm within the presented wavelength tunable range. Fast different wavelength excitation and three-dimensionally rendered imaging of Hela cell mitochondria and cytoskeletons and mouse muscle fibers were demonstrated. Significantly, the proposed system can improve the quality of two-color TFMPEM images through different excitation wavelengths to obtain higher-quality fluorescent signals in multiple-fluorophore measurements.

  7. JENOPTIK diode lasers and bars optimized for high-power applications in the NIR range

    Science.gov (United States)

    Zorn, M.; Hülsewede, R.; Schulze, H.; Sebastian, J.; Hennig, P.; Schröder, D.

    2010-02-01

    Laser diodes and laser bars for the high-volume wavelength ranges at 808 nm and 940 nm are available in optimized design and high quality. However, a lot of other wavelengths in the NIR are needed for specialized applications also requiring high stability, reliability and a good efficiency with a good beam quality. An efficient adaptation of the laser diode design to optimize the laser performance at the customized wavelength is highly desirable. At JENOPTIK Diode Lab (JDL) we therefore focus on a flexible and competitive laser diode design resulting in a high output power and a high efficiency at reasonable production costs. Starting from excellent laser bars at 808 nm and 940 nm laser bars with emission wavelengths around 790 nm, 830 nm, 880nm (cw) and 940 nm (pulsed operation) are developed. For 792 nm a maximum output power of 90 W and an efficiency of 55 % has been achieved with an expected lifetime of more than 15000 hours. At 825 nm a maximum efficiency of 60 % and 60 W output power for more than 20.000 h with a high degree of polarization can be presented. Changing the quantum well material for 885 nm the output power reaches 125W with 63% efficiency also for more than 25.000 hours. Laser bars for pulsed applications (quasi-cw) at 940 nm result in an output power of 500 W with an efficiency of 60 %.

  8. Generation of attosecond x-ray pulses with a multi-cycle two-color ESASE scheme

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Y.; Huang, Z.; Ratner, D.; Bucksbaum, P.; /SLAC; Merdji, H.; /Saclay /SLAC

    2009-03-04

    Generation of attosecond x-ray pulses is attracting much attention within the x-ray free-electron laser (FEL) user community. Several schemes using extremely short laser pulses to manipulate the electron bunches have been proposed. In this paper, we extend the attosecond two-color ESASE scheme proposed by Zholents et al. to the long optical cycle regime using a second detuned laser and a tapered undulator. Both lasers can be about ten-optical-cycles long, with the second laser frequency detuned from the first to optimize the contrast between the central and side current spikes. A tapered undulator mitigates the degradation effect of the longitudinal space charge (LSC) force in the undulator and suppresses the FEL gain of all side current peaks. Simulations using the LCLS parameters show a single attosecond x-ray spike of {approx} 110 attoseconds can be produced. The second laser can also be detuned to coherently control the number of the side x-ray spikes and the length of the radiation pulse.

  9. Long-Range Coulomb Effect in Intense Laser-Driven Photoelectron Dynamics

    Science.gov (United States)

    Quan, Wei; Hao, Xiaolei; Chen, Yongju; Yu, Shaogang; Xu, Songpo; Wang, Yanlan; Sun, Renping; Lai, Xuanyang; Wu, Chengyin; Gong, Qihuang; He, Xiantu; Liu, Xiaojun; Chen, Jing

    2016-06-01

    In strong field atomic physics community, long-range Coulomb interaction has for a long time been overlooked and its significant role in intense laser-driven photoelectron dynamics eluded experimental observations. Here we report an experimental investigation of the effect of long-range Coulomb potential on the dynamics of near-zero-momentum photoelectrons produced in photo-ionization process of noble gas atoms in intense midinfrared laser pulses. By exploring the dependence of photoelectron distributions near zero momentum on laser intensity and wavelength, we unambiguously demonstrate that the long-range tail of the Coulomb potential (i.e., up to several hundreds atomic units) plays an important role in determining the photoelectron dynamics after the pulse ends.

  10. Applications of free electron lasers in the UV

    Energy Technology Data Exchange (ETDEWEB)

    Couprie, M.E.

    1994-12-31

    The first applications of the UV Free Electron Lasers (FEL) show the advance to a stage of maturity for such sources. Two-color experiments coupling storage ring FEL and synchrotron radiation offer the wide range of use. (TEC). 26 refs., 7 figs., 2 tabs.

  11. Compact multispectral continuous zoom camera for color and SWIR vision with integrated laser range finder

    Science.gov (United States)

    Hübner, M.; Gerken, M.; Achtner, Bertram; Kraus, M.; Münzberg, M.

    2014-06-01

    In an electro-optical sensor suite for long range surveillance tasks the optics for the visible (450nm - 700nm) and the SWIR spectral wavelength range (900nm - 1700 nm) are combined with the receiver optics of an integrated laser range finder (LRF) .The incoming signal from the observed scene and the returned laser pulse are collected within the common entrance aperture of the optics. The common front part of the optics is a broadband corrected lens design from 450 - 1700nm wavelength range. The visible spectrum is split up by a dichroic beam splitter and focused on a HDTV CMOS camera. The returned laser pulse is spatially separated from the scene signal by a special prism and focused on the laser receiver diode of the integrated LRF. The achromatic lens design has a zoom factor 14 and F#2.6 in the visible path. In the SWIR path the F-number is adapted to the corresponding chip dimensions . The alignment of the LRF with respect to the SWIR camera line of sight can be controlled by adjustable integrated wedges. The two images in the visible and the SWIR spectral range match in focus and field of view (FOV) over the full zoom range between 2° and 22° HFOV. The SWIR camera has a resolution of 640×512 pixels. The HDTV camera provides a resolution of 1920×1080. The design and the performance parameters of the multispectral sensor suite is discussed.

  12. High-Precision Lunar Ranging and Gravitational Parameter Estimation With the Apache Point Observatory Lunar Laser-ranging Operation

    Science.gov (United States)

    Johnson, Nathan H.

    This dissertation is concerned with several problems of instrumentation and data analysis encountered by the Apache Point Observatory Lunar Laser-ranging Operation. Chapter 2 considers crosstalk between elements of a single-photon avalanche photodiode detector. Experimental and analytic methods were developed to determine crosstalk rates, and empirical findings are presented. Chapter 3 details electronics developments that have improved the quality of data collected by detectors of the same type. Chapter 4 explores the challenges of estimating gravitational parameters on the basis of ranging data collected by this and other experiments and presents resampling techniques for the derivation of standard errors for estimates of such parameters determined by the Planetary Ephemeris Program (PEP), a solar-system model and data-fitting code. Possible directions for future work are discussed in Chapter 5. A manual of instructions for working with PEP is presented as an appendix.

  13. New Laser Doppler Velocimetry with Wide Dynamic Range and Clear Directional Discrimination

    Institute of Scientific and Technical Information of China (English)

    GUI Hua-Qiao; L(U) Liang; HE De-Yong; XU Jun; XIE Jian-Ping; ZHAO Tian-Peng; WANG An-Ting; MING Hai

    2005-01-01

    @@ We present a new laser Doppler velocimetry based on self-mixing effect using a single longitudinal-mode verticalcavity surface-emitting laser modulated by a dynamic triangular current. It can indicate the direction of velocity without ambiguity in a wide dynamic range of 5.2-479.9mm/s. The accuracy of velocity measurement is better than 3.1% in the whole velocity range when a diffusing target is used for measurements. More interestingly, it works very well on different diffusing surfaces, even on a black glossy photographic paper.

  14. Range Resolved CO2 Atmospheric Backscattering Measurements Using Fiber Lasers and RZPN Code Modulation

    Science.gov (United States)

    Burris, John

    2011-01-01

    We report the use of a return-to- zero (RZPN) pseudo noise modulation technique for making range resolved measurements of CO2 within the planetary boundary layer (PBL) using commercial, off-the-shelf, components. Conventional, range resolved, DIAL measurements require laser pulse widths that are significantly shorter than the desired spatial resolution and necessitate using pulses whose temporal spacing is such that scattered returns from only a single pulse are observed by the receiver at any one time (for the PBL pulse separations must be greater than approximately 20 microseconds). This imposes significant operational limitations when using currently available fiber lasers because of the resulting low duty cycle (less than approximately 0.0005) and consequent low average laser output power. The RZPN modulation technique enables a fiber laser to operate at much higher duty cycles (approaching 0.04) thereby more effectively utilizing the amplifier's output. This increases the counts received by approximately two orders of magnitude. Our approach involves employing two distributed feedback lasers (DFB), each modulated by a different RPZN code, whose outputs are then amplified by a CW fiber amplifier. One laser is tuned to a CO2 absorption line; the other operates offline thereby permitting the simultaneous acquisition of both on and offline signals using independent RZPN codes. This minimizes the impact of atmospheric turbulence on the measurement. The on and offline signals are retrieved by deconvolving the return signal using the appropriate kernels.

  15. Laser materials for the 0.67-microns to 2.5-microns range

    Science.gov (United States)

    Toda, Minoru; Zamerowski, Thomas J.; Ladany, Ivan; Martinelli, Ramon U.

    1987-01-01

    Basic requirements for obtaining injection laser action in III-V semiconductors are discussed briefly. A detailed review is presented of materials suitable for lasers emitting at 0.67, 1.44, 1.93, and 2.5 microns. A general approach to the problem is presented, based on curves of materials properties published by Sasaki et al. It is also shown that these curves, although useful, may need correction in certain ranges. It is deduced that certain materials combinations, either proposed in the literature or actually tried, are not appropriate for double heterostructure lasers, because the refractive index of the cladding material is higher than the index of the active material, thus resulting in no waveguiding, and high threshold currents. Recommendations are made about the most promising approach to the achievement of laser action in the four wavelengths mentioned above.

  16. Two-Color Surface Photometry of Brightest Cluster Members

    CERN Document Server

    Garilli, B; Andreon, S; MacCagni, D; Carrasco, L; Recillas, E; Garilli, Bianca; Sangalli, Giorgio; Andreon, Stefano; Maccagni, Dario; Carrasco, Luis; Recillas, Elsa

    1997-01-01

    The Gunn g, r and i CCD images of a representative sample of 17 Brightest Cluster Galaxies (BCM) have been analyzed in order to derive surface brightness and color profiles, together with geometrical parameters like eccentricity and position angle. The sample includes both X-ray and optically selected clusters, ranging in redshift from z=0.049 to z=0.191. We find that BCMs are substantially well described by de Vaucouleurs' law out to radii of cases we find a surface brightness excess with respect to the $r^{1/4}$ law, which for A150 is coupled with a change in the $g-r$ color. The rest frame colors of BCMs do not show any intrinsic dispersion. By parametrizing the environment with the local galaxy number density, we find that it is correlated with the BCM extension, i.e. BCMs with larger effective radii are found in denser environments.

  17. Maternal detection of neonatal jaundice during birth hospitalization using a novel two-color icterometer

    National Research Council Canada - National Science Library

    Bolajoko O Olusanya; Tina M Slusher; Donald O Imosemi; Abieyuwa A Emokpae

    2017-01-01

    .... This study therefore, set out to evaluate the performance of a -two-color icterometer (BilistripTM) as a possible screening tool for detecting significant jaundice by mothers or care-givers in the first week of life...

  18. Maximum detection range limitation of pulse laser radar with Geiger-mode avalanche photodiode array

    Science.gov (United States)

    Luo, Hanjun; Xu, Benlian; Xu, Huigang; Chen, Jingbo; Fu, Yadan

    2015-05-01

    When designing and evaluating the performance of laser radar system, maximum detection range achievable is an essential parameter. The purpose of this paper is to propose a theoretical model of maximum detection range for simulating the Geiger-mode laser radar's ranging performance. Based on the laser radar equation and the requirement of the minimum acceptable detection probability, and assuming the primary electrons triggered by the echo photons obey Poisson statistics, the maximum range theoretical model is established. By using the system design parameters, the influence of five main factors, namely emitted pulse energy, noise, echo position, atmospheric attenuation coefficient, and target reflectivity on the maximum detection range are investigated. The results show that stronger emitted pulse energy, lower noise level, more front echo position in the range gate, higher atmospheric attenuation coefficient, and higher target reflectivity can result in greater maximum detection range. It is also shown that it's important to select the minimum acceptable detection probability, which is equivalent to the system signal-to-noise ratio for producing greater maximum detection range and lower false-alarm probability.

  19. Technique Errors and Limiting Factors in Laser Ranging to Geodetic Satellites

    Science.gov (United States)

    Appleby, G. M.; Luceri, V.; Mueller, H.; Noll, C. E.; Otsubo, T.; Wilkinson, M.

    2012-12-01

    The tracking stations of the International Laser Ranging Service (ILRS) global network provide to the Data Centres a steady stream of very precise laser range normal points to the primary geodetic spherical satellites LAGEOS (-1 and -2) and Etalon (-1 and -2). Analysis of these observations to determine instantaneous site coordinates and Earth orientation parameters provides a major contribution to ongoing international efforts to define a precise terrestrial reference frame, which itself supports research into geophysical processes at the few mm level of precision. For example, the latest realization of the reference frame, ITRF2008, used weekly laser range solutions from 1983 to 2009, the origin of the Frame being determined solely by the SLR technique. However, in the ITRF2008 publication, Altamimi et al (2011, Journal of Geodesy) point out that further improvement in the ITRF is partly dependent upon improving an understanding of sources of technique error. In this study we look at SLR station hardware configuration that has been subject to major improvements over the last four decades, at models that strive to provide accurate translations of the laser range observations to the centres of mass of the small geodetic satellites and at the considerable body of work that has been carried out via orbital analyses to determine range corrections for some of the tracking stations. Through this study, with specific examples, we start to put together an inventory of system-dependent technique errors that will be important information for SLR re-analysis towards the next realization of the ITRF.

  20. Indetermination of particle sizing by laser diffraction in the anomalous size ranges

    Science.gov (United States)

    Pan, Linchao; Ge, Baozhen; Zhang, Fugen

    2017-09-01

    The laser diffraction method is widely used to measure particle size distributions. It is generally accepted that the scattering angle becomes smaller and the angles to the location of the main peak of scattered energy distributions in laser diffraction instruments shift to smaller values with increasing particle size. This specific principle forms the foundation of the laser diffraction method. However, this principle is not entirely correct for non-absorbing particles in certain size ranges and these particle size ranges are called anomalous size ranges. Here, we derive the analytical formulae for the bounds of the anomalous size ranges and discuss the influence of the width of the size segments on the signature of the Mie scattering kernel. This anomalous signature of the Mie scattering kernel will result in an indetermination of the particle size distribution when measured by laser diffraction instruments in the anomalous size ranges. By using the singular-value decomposition method we interpret the mechanism of occurrence of this indetermination in detail and then validate its existence by using inversion simulations.

  1. Analysis of one-way laser ranging data to LRO, time transfer and clock characterization

    Science.gov (United States)

    Bauer, S.; Hussmann, H.; Oberst, J.; Dirkx, D.; Mao, D.; Neumann, G. A.; Mazarico, E.; Torrence, M. H.; McGarry, J. F.; Smith, D. E.; Zuber, M. T.

    2017-02-01

    We processed and analyzed one-way laser ranging data from International Laser Ranging Service ground stations to NASA's Lunar Reconnaissance Orbiter (LRO), obtained from June 13, 2009 until September 30, 2014. We pair and analyze the one-way range observables from station laser fire and spacecraft laser arrival times by using nominal LRO orbit models based on the GRAIL gravity field. We apply corrections for instrument range walk, as well as for atmospheric and relativistic effects. In total we derived a tracking data volume of ≈ 3000 hours featuring 64 million Full Rate and 1.5 million Normal Point observations. From a statistical analysis of the dataset we evaluate the experiment and the ground station performance. We observe a laser ranging measurement precision of 12.3 cm in case of the Full Rate data which surpasses the LOLA timestamp precision of 15 cm. The averaging to Normal Point data further reduces the measurement precision to 5.6 cm. We characterized the LRO clock with fits throughout the mission time and estimated the rate to 6.9 × 10-8, the aging to 1.6 × 10-12/day and the change of aging to 2.3 × 10-14 /day2over all mission phases. The fits also provide referencing of onboard time to the TDB time scale at a precision of 166 ns over two and 256 ns over all mission phases, representing ground to space time transfer. Furthermore we measure ground station clock differences from the fits as well as from simultaneous passes which we use for ground to ground time transfer from common view observations. We observed relative offsets ranging from 33 to 560 ns and relative rates ranging from 2 × 10-13 to 6 × 10-12 between the ground station clocks during selected mission phases. We study the results from the different methods and discuss their applicability for time transfer.

  2. Advanced technologies in the ASI MLRO towards a new generation laser ranging system

    Science.gov (United States)

    Varghese, Thomas; Bianco, Giuseppe

    1994-01-01

    Matera Laser Ranging Observatory (MLRO) is a high performance, highly automated optical and astronomical observatory currently under design and development by AlliedSignal for the Italian Space Agency (ASI). It is projected to become operational at the Centro Geodesia Spaziale in Matera, Italy, in 1997. MLRO, based on a 1.5-meter astronomical quality telescope, will perform ranging to spacecraft in earthbound orbits, lunar reflectors, and specially equipped deep space missions. The primary emphasis during design is to incorporate state-of-the-art technologies to produce an intelligent, automated, high accuracy ranging system that will mimic the characteristic features of a fifth generation laser ranging system. The telescope has multiple ports and foci to support future experiments in the areas of laser communications, lidar, astrometry, etc. The key features providing state-of-the-art ranging performance include: a diode-pumped picosecond (50 ps) laser, high speed (3-5 GHz) optoelectronic detection and signal processing, and a high accuracy (6 ps) high resolution (less than 2 ps) time measurement capability. The above combination of technologies is expected to yield millimeter laser ranging precision and accuracy on targets up to 300,000 km, surpassing the best operational instrument performance to date by a factor of five or more. Distributed processing and control using a state-of-the-art computing environment provides the framework for efficient operation, system optimization, and diagnostics. A computationally intelligent environment permits optimal planning, scheduling, tracking, and data processing. It also supports remote access, monitor, and control for joint experiments with other observatories.

  3. Dynamic Range of Vertical Cavity Surface Emitting Lasers in Multimode Links

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.L.T.; Dalal, R.V.; Ram, R.J.; Choquette, K.D.

    1999-07-07

    The authors report spurious free dynamic range measurements of 850nm vertical cavity surface emitting lasers in short multimode links for radio frequency communication. For a 27m fiber link, the dynamic range at optimal bias was greater than 95dB-Hz{sup 2/3} for modulation frequencies between 1 and 5.5 GHz, which exceeds the requirements for antenna remoting in microcellular networks. In a free space link, they have measured the highest dynamic range in an 850nm vertical cavity surface emitting laser of 113dB-Hz{sup 2/3} at 900MHz. We have also investigated the effects of modal noise and differential mode delay on the dynamic range for longer lengths of fiber.

  4. All-fiber broad-range self-sweeping Yb-doped fiber laser

    Science.gov (United States)

    Lobach, Ivan A.; Kablukov, Sergey A.; Podivilov, Evgeniy V.; Babin, Sergey A.

    2012-02-01

    The effect of broad-range self-sweeping in Yb-doped fiber laser has been demonstrated experimentally for the first time. The self-sweeping effect is observed in an all-fiber laser configuration with a double-clad Yb-doped fiber and a cavity formed by a broad-band fiber loop mirror and Fresnel reflection from one cleaved end. The sweep range is limited by the width of the broad-band reflector and reaches up to 16nm. It is found that the self-sweeping effect is related to selfpulsations. So the sweep rate is increased with an increase in pump power and is decreased with increasing cavity length. RF and optical spectra (linewidth is measured to be not more than 100 MHz) show that during the evolution of a single pulse a small number of longitudinal modes take a part in lasing. Based on these results we propose a model describing dynamics of the laser frequency. The model is based on the spatial hole burning effect and the gain saturation in Yb laser transition, and takes into account self-pulsations of the laser. Theoretical estimation for pulse to pulse change of lasing frequency is in good agreement with experimental data.

  5. The Moon as a Laser-ranged Test Body for General Relativity and New Gravitational Physics

    Science.gov (United States)

    Dell'Agnello, Simone; Currie, Douglas

    Since the 1970s Lunar Laser Ranging (LLR) to the Apollo/Lunokhod Cube Corner Retroreflector (CCR) Arrays supplied some of the best tests of General Relativity (GR): possible changes in the gravitational constant, gravitational self-energy (PPN parameter beta), weak equivalence principle, geodetic precession, inverse-square force-law. Secondly, LLR has provided significant information on the composition of the deep interior of the Moon. LLR physics analysis also allows to set constraints on extensions of GR (like spacetime torsion) and, possibly, on new gravitational physics which may explain the gravitational universe without Dark Matter and Dark Energy (like, for example, Non-Minimally Coupled gravity, NMC). LLR is the only Apollo/Lunokhod experiment still in operation, since 45 years. In the 1970s Apollo/Lunokohd LLR Arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo/Lunokhod CCR arrays dominate the error budget. With the US/Italy project "LLRRA21/MoonLIGHT (Lunar Laser Ranging Retroreflector Array for the 21st century / Moon Laser Instrumentation for General relativity High accuracy Tests)", University of Maryland and INFN-LNF developed and tested a next-generation LLR payload made by a single, large CCR (100 mm diameter), unaffected by the effect of librations. In fact, we will show that MoonLIGHT reflectors will improve the LLR accuracy by a factor of ten to one hundred in a few years. INFN-LNF also developed a laser retroreflector micropayload to be deployed on the lunar surface to be laser-ranged by lunar orbiters. The latter micropayload will further extend the physics reach of Apollo, Lunokhod and MoonLIGHT CCRs to improve all precision tests of GR and new gravitational physics using LLR data. As an added value for the LRR and SLR (Satellite Laser ranging) disciplines INFN-LNF built and is

  6. Compact short-pulse laser for near-field range-gated imaging

    Science.gov (United States)

    Zutavern, Fred J.; Helgeson, Wesley D.; Loubriel, Guillermo M.; Yates, George J.; Gallegos, Robert A.; McDonald, Thomas E., Jr.

    1997-05-01

    This paper describes a compact laser, which produces high power, wide-angle emission for a near-field, range-gated, imaging system. The optical pulses are produced by a 100 element laser diode array (LDA) which is pulsed with a GaAs, photoconductive semiconductor switch (PCSS). The LDA generates 100 ps long, gain-switched, optical pulses at 904 nm when it is driven with 3 ns, 400 A, electrical pulses from a high gain PCSS. Gain switching is facilitated with this many lasers by using a low impedance circuit to drive an array of lasers, which are connected electrically in series. The total optical energy produced per pulse is 100 microjoules corresponding to a total peak power of 100 kW. The entire laser system, including prime power (a nine volt battery), pulse charging, PCSS, and LDA, is the size of a small, hand-held flashlight, System lifetime, which is presently limited by the high gain PCSS, is an active area of research and development. Present limitations and potential improvements will be discussed. The complete range-gated imaging system is based on complementary technologies: high speed optical gating with intensified charge coupled devices (ICCD) developed at Los Alamos National Laboratory and high gain, PCSS-driven LDAs developed at Sandia National Laboratories. The system is designed for use in highly scattering media such as turbid water or extremely dense fog or smoke. The short optical pulses from the laser and high speed gating of the ICCD are synchronized to eliminate the back-scattered light from outside the depth of the field of view (FOV) which may be as short as a few centimeters. A high speed photodiode can be used to trigger the intensifier gate and set the range-gated FOV precisely on the target. The ICCD and other aspects of the imaging system are discussed in a separate paper.

  7. Goulphar: rapid access and expertise for standard two-color microarray normalization methods

    Directory of Open Access Journals (Sweden)

    Servant Nicolas

    2006-10-01

    Full Text Available Abstract Background Raw data normalization is a critical step in microarray data analysis because it directly affects data interpretation. Most of the normalization methods currently used are included in the R/BioConductor packages but it is often difficult to identify the most appropriate method. Furthermore, the use of R commands for functions and graphics can introduce mistakes that are difficult to trace. We present here a script written in R that provides a flexible means of access to and monitoring of data normalization for two-color microarrays. This script combines the power of BioConductor and R analysis functions and reduces the amount of R programming required. Results Goulphar was developed in and runs using the R language and environment. It combines and extends functions found in BioConductor packages (limma and marray to correct for dye biases and spatial artifacts. Goulphar provides a wide range of optional and customizable filters for excluding incorrect signals during the pre-processing step. It displays informative output plots, enabling the user to monitor the normalization process, and helps adapt the normalization method appropriately to the data. All these analyses and graphical outputs are presented in a single PDF report. Conclusion Goulphar provides simple, rapid access to the power of the R/BioConductor statistical analysis packages, with precise control and visualization of the results obtained. Complete documentation, examples and online forms for setting script parameters are available from http://transcriptome.ens.fr/goulphar/.

  8. A high resolution laser ranging system based on time-correlated single-photon counting technology

    Science.gov (United States)

    Yang, Yixin; Wang, Huanqin; Huang, Zhe; Cao, Yangyang; Gui, Huaqiao

    2014-12-01

    Laser ranging has become an important method for both distance measurements and acquisition of threedimensional (3D) images. In this paper, a laser ranging system based on Time-Correlated Single-Photon Counting technology (TCSPC) is developed. A Geiger-mode avalanche photodiode (G-APD), which has the ability of detecting single-photon events, is used to capture the weak light scattered from the long-range target. In order to improve the ranging resolution of TCSPC based measurement system, a high repetition frequency of subnanosecond narrow pulse generator circuit based on the avalanche effect of RF-BJT is designed and applied as the light source. Moreover, some optimized optical light designs have been done to improve the system signal to noise rate (SNR), including using a special aspherical lens as projecting lens, adopting a telephoto camera lens with small view angle and short depth of field before detector. Experimental tests for evaluation of the laser raging system performance are described. As a means of echo signal analysis, three different algorithms have been introduced, in which the cross-correlation algorithm was demonstrated to be the most effective algorithm to determining the round trip time to a target, even based on histograms with a significant amount of background noise photons. It was found that centimeter ranging resolution can be achieved thanks to the use of Time-to-Digital Converter (TDC) with picosecond resolution and the Cross-Correlation algorithm. The proposed laser ranging system has advantages of high range resolution, short response time and simple structure, which was potential applications for 3D object recognition, computer vision, reverse engineering and virtual reality.

  9. Element Selective Probe of the Ultra-Fast Magnetic Response to an Element Selective Excitation in Fe-Ni Compounds Using a Two-Color FEL Source

    Directory of Open Access Journals (Sweden)

    Eugenio Ferrari

    2017-01-01

    Full Text Available The potential of the two-color mode implemented at the FERMI free-electron laser (FEL source for pumping and probing selectively different atomic species has been demonstrated by time-resolved scattering experiments with permalloy (FeNi alloy and NiFe2O4 samples. We monitored the ultra-fast demagnetization of Ni induced by the pump FEL pulse, by tuning the linearly-polarized FEL probe pulse to the Ni-3p resonance and measuring the scattered intensity in the transverse magneto-optical Kerr effect geometry. The measurements were performed by varying the intensity of the FEL pump pulse, tuning its wavelength to and off of the Fe-3p resonance, and by spanning the FEL probe pulse delays across the 300–900 fs range. The obtained results have evidenced that for the case of NiFe2O4, there is a sensible difference in the magnetic response at the Ni site when the pump pulse causes electronic excitations at the Fe site.

  10. Interspacecraft link simulator for the laser ranging interferometer onboard GRACE Follow-On.

    Science.gov (United States)

    Sanjuan, Josep; Gohlke, Martin; Rasch, Stefan; Abich, Klaus; Görth, Alexander; Heinzel, Gerhard; Braxmaier, Claus

    2015-08-01

    Link acquisition strategies are key aspects for interspacecraft laser interferometers. We present an optical fiber-based setup able to simulate the interspacecraft link for the laser ranging interferometer (LRI) on gravity recovery and climate experiment Follow-On. It allows one to accurately recreate the far-field intensity profile depending on the mispointing between the spacecraft, Doppler shifts, and spacecraft attitude jitter. Furthermore, it can be used in late integration stages of the mission, since no physical contact with the spacecraft is required. The setup can also be easily adapted to other similar missions and different acquisition algorithms.

  11. Earth rotation, station coordinates and orbit determination from satellite laser ranging

    Science.gov (United States)

    Murata, Masaaki

    The Project MERIT, a special program of international colaboration to Monitor Earth Rotation and Intercompare the Techniques of observation and analysis, has come to an end with great success. Its major objective was to evaluate the ultimate potential of space techniques such as VLBI and satellite laser ranging, in contrast with the other conventional techniques, in the determination of rotational dynamics of the earth. The National Aerospace Laboratory (NAL) has officially participated in the project as an associate analysis center for satellite laser technique for the period of the MERIT Main Campaign (September 1983-October 1984). In this paper, the NAL analysis center results are presented.

  12. FMCW laser range-finder with an avalanche photodiode working as an optoelectronic mixer

    Science.gov (United States)

    Dupuy, David; Lescure, Marc; Tap-Beteille, Helene

    2002-01-01

    A Frequency Modulation Continuous Wave (FMCW) laser range- finder has been designed for distances from 1 m to 20 m with cooperative or diffusing targets. This range-finder is compared to a phase shift laser range-finder. A heterodyne photoreception method is studied. In order to reduce noise, the nonlinear current-voltage characteristic of the APD is used to obtain an optoelectronic mixer. The photocurrent gain is modulated by the VCO signal working as a local oscillator (LO). The optical and electrical LO injection methods are studied. The theoretical analysis using the Miller model and thermal effects are compared with the first experimental results. The electrical LO injection gives a better ratio-to-noise than the optical LO injection. For electrical injection, it is shown that the heterodyne conversion gain can reach the maximal theoretical value 0.5.

  13. Hollow Retroreflectors for Lunar Laser Ranging at Goddard Space Flight Center

    Science.gov (United States)

    Preston, Alix M.; Merkowitz, Stephen M.

    2012-01-01

    Laser ranging to the retroreflector arrays placed on the lunar surface by the Apollo astronauts and the Soviet Luna missions have dramatically increased our understanding of gravitational physics along with Earth and Moon geophysics, geodesy, and dynamics. Although the precision of the range measurements has historically been limited by the ground station capabilities, advances in the APOLLO instrument at the Apache Point facility in New Mexico is beginning to be limited by errors associated with the lunar arrays. At Goddard Space Flight Center, we have developed a facility where we can design, build, and test next-generation hollow retroreflectors for Lunar Laser Ranging. Here we will describe this facility as well as report on the bonding techniques used to assemble the retroreflectors. Results from investigations into different high reflectivity mirror coatings, as well as dust mitigation coatings will also be presented.

  14. Using mid-range laser scanners to digitize cultural-heritage sites.

    Science.gov (United States)

    Spring, Adam P; Peters, Caradoc; Minns, Tom

    2010-01-01

    Here, we explore new, more accessible ways of modeling 3D data sets that both professionals and amateurs can employ in areas such as architecture, forensics, geotechnics, cultural heritage, and even hobbyist modeling. To support our arguments, we present images from a recent case study in digital preservation of cultural heritage using a mid-range laser scanner. Our appreciation of the increasing variety of methods for capturing 3D spatial data inspired our research. Available methods include photogrammetry, airborne lidar, sonar, total stations (a combined electronic and optical survey instrument), and midand close-range scanning.1 They all can produce point clouds of varying density. In our case study, the point cloud produced by a mid-range scanner demonstrates how open source software can make modeling and disseminating data easier. Normally, researchers would model this data using expensive specialized software, and the data wouldn't extend beyond the laser-scanning community.

  15. Large field-of-view range-gated laser imaging based on image fusion

    Science.gov (United States)

    Ren, Pengdao; Wang, Xinwei; Sun, Liang; You, Ruirong; Lei, Pingshun; Zhou, Yan

    2016-11-01

    Laser range-gated imaging has great potentials in remote night surveillance with far detection distance and high resolution, even if under bad weather conditions such as fog, snow and rain. However, the field of view (FOV) is smaller than large objects like buildings, towers and mountains, thus only parts of targets are observed in one single frame, so that it is difficult for targets identification. Apparently, large FOV is beneficial to solve the problem, but the detection range is not available due to low illumination density in a large field of illumination matching with the FOV. Therefore, a large field-of-view range-gated laser imaging is proposed based on image fusion in this paper. Especially an image fusion algorithm has been developed for low contrast images. First of all, an infrared laser range-gated system is established to acquire gate images with small FOV for three different scenarios at night. Then the proposed image fusion algorithm is used for generating panoramas for the three groups of images respectively. Compared with raw images directly obtained by the imaging system, the fused images have a larger FOV with more detail target information. The experimental results demonstrate that the proposed image fusion algorithm is effective to expand the FOV of range-gated imaging.

  16. Laser Ranging to the Moon: How Evolving Technology Enables New Science

    Science.gov (United States)

    Faller, James

    2010-03-01

    Technological advances have long been the enabler of scientific progress. The invention of the laser is a prime example of this symbiotic relationship between technical progress and scientific advances. The laser, which today is omnipresent in each of our lives, made its first appearance during the time that I was a graduate student in Professor Dicke's group at Princeton. A major change occurring during that time period was that technology was transforming the study of gravitational physics from just a theoretical subject into also an experimental subject where one could hope to measure things using by-then-available laboratory technologies and techniques. During this same time, the idea for the lunar laser ranging experiment was born. The history and accomplishments of this experiment--a still ongoing experiment which is one of the real scientific triumphs of NASA's Apollo program--will be given.

  17. High-power pulsed laser diodes emitting in the range 1.5 – 1.6 μm

    Energy Technology Data Exchange (ETDEWEB)

    Gorlachuk, P V; Ryaboshtan, Yu L; Ladugin, M A; Padalitsa, A A; Marmalyuk, A A; Kurnosov, V D; Kurnosov, K V; Zhuravleva, O V; Romantsevich, V I; Chernov, R V; Ivanov, A V; Simakov, V A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2013-09-30

    This paper examines approaches for increasing the output pulse power of laser diodes based on MOVPE InGaAs/AlGaInAs/InP heterostructures and emitting in the range 1.5 – 1.6 μm. We demonstrate that optimising waveguide layer parameters may ensure an increase in the quantum efficiency of the laser diodes and a reduction in their internal optical loss. Characterisation results are presented for laser diodes based on the proposed heterostructures. (lasers)

  18. Compressed sensing for super-resolution spatial and temporal laser detection and ranging

    Science.gov (United States)

    Laurenzis, Martin; Schertzer, Stephane; Christnacher, Frank

    2016-10-01

    In the past decades, laser aided electro-optical sensing has reached high maturity and several commercial systems are available at the market for various but specific applications. These systems can be used for detection i.e. imaging as well as ranging. They cover laser scanning devices like LiDAR and staring full frame imaging systems like laser gated viewing or LADAR. The sensing capabilities of these systems is limited by physical parameter (like FPA array size, temporal band width, scanning rate, sampling rate) and is adapted to specific applications. Change of system parameter like an increase of spatial resolution implies the setup of a new sensing device with high development cost or the purchase and installation of a complete new sensor unit. Computational imaging approaches can help to setup sensor devices with flexible or adaptable sensing capabilities. Especially, compressed sensing is an emerging computational method which is a promising candidate to realize super-resolution sensing with the possibility to adapt its performance to various sensing tasks. It is possible to increase sensing capabilities with compressed sensing to gain either higher spatial and/or temporal resolution. Then, the sensing capabilities depend no longer only on the physical performance of the device but also on the computational effort and can be adapted to the application. In this paper, we demonstrate and discuss laser aided imaging using CS for super-resolution tempo-spatial imaging and ranging.

  19. Analyses of Valid Range for the Linear Approximation in a Single-Mode Laser

    Institute of Scientific and Technical Information of China (English)

    CHENGQing-Hua; CAOLi; WANGJun; WUDa-Jin

    2004-01-01

    Using the linear approximation method, we calculated the steady-state mean normalized intensity fluctuation for a loss-noise model of a single-mode laser driven by a pump noise and a quantum noise, whose real part and imaginary part are cross-correlated. We analyzed the valid range for the linear approximation method by studying the influences on the steady-state mean normalized intensity fluctuation by the cross-correlation coefficient, the intensities of the quantum and pump noise, the net gain, and the amplitude and frequency of the input signal, and we found that the valid range becomes wider when the cross-correlation between the real and imaginary part of quantum noise is weaker, the noise intensities of quantum and pump are weaker, the laser system is far from the threshold and the signal has smaller amplitude and higher frequency.

  20. Asymmetric dihedral angle offsets for large-size lunar laser ranging retroreflectors

    Science.gov (United States)

    Otsubo, Toshimichi; Kunimori, Hiroo; Noda, Hirotomo; Hanada, Hideo; Araki, Hiroshi; Katayama, Masato

    2011-08-01

    The distribution of two-dimensional velocity aberration is off-centered by 5 to 6 microradians in lunar laser ranging, due to the stable measurement geometry in the motion of the Earth and the Moon. The optical responses of hollow-type retroreflectors are investigated through numerical simulations, especially focusing on large-size, single-reflector targets that can ultimately minimize the systematic error in future lunar laser ranging. An asymmetric dihedral angle offset, i.e. setting unequal angles between the three back faces, is found to be effective for retroreflectors that are larger than 100 mm in diameter. Our numerical simulation results reveal that the optimized return energy increases approximately 3.5 times more than symmetric dihedral angle cases, and the optimized dihedral angle offsets are 0.65-0.8 arcseconds for one angle, and zeroes for the other two angles.

  1. Dichroic atomic vapor laser lock with multi-gigahertz stabilization range

    Energy Technology Data Exchange (ETDEWEB)

    Pustelny, S., E-mail: pustelny@uj.edu.pl [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Schultze, V.; Scholtes, T. [Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, D-07745 Jena (Germany); Budker, D. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Helmholtz-Institut Mainz, Johannes Gutenberg Universität Mainz, 55128 Mainz (Germany)

    2016-06-15

    A dichroic atomic vapor laser lock (DAVLL) system exploiting buffer-gas-filled millimeter-scale vapor cells is presented. This system offers similar stability as achievable with conventional DAVLL system using bulk vapor cells, but has several important advantages. In addition to its compactness, it may provide continuous stabilization in a multi-gigahertz range around the optical transition. This range may be controlled either by changing the temperature of the vapor or by application of a buffer gas under an appropriate pressure. In particular, we experimentally demonstrate the ability of the system to lock the laser frequency between two hyperfine components of the {sup 85}Rb ground state or as far as 16 GHz away from the closest optical transition.

  2. Molecular laser studies in the 7-16. mu. m range. Annual report, 1 June 1975-30 September 1976

    Energy Technology Data Exchange (ETDEWEB)

    Colemen, P.D.

    1976-10-01

    An exploratory research effort to find new molecular lasers in the 7-16 ..mu..m wavelength range, in particular lasers with wavelengths at 7.7, 8.6, and 16 ..mu..m wavelengths, is described. The specific initial objectives were: (1) to explore Raman scattering of CO/sub 2/ radiation in a liquid and molecular gas and (2) to explore chemically excited metal fluorides as laser candidates for the 12-16 ..mu..m wavelength range.

  3. Satellite Laser Ranging Photon-Budget Calculations for a Single Satellite Cornercube Retroreflector: Attitude Control Tolerance

    Science.gov (United States)

    2015-11-01

    UNCLASSIFIED Satellite Laser Ranging Photon-Budget Calculations for a Single Satellite Cornercube Retroreflector: Attitude Control Tolerance Philip C...the SLR station, and the direction of the satellite from the SLR station. The required attitude control tolerance is to within 17◦ of the optimal... attitude control strategy determined in the present work. A pre-launch measurement of the re- flectance (diffraction) pattern of each retroreflector is

  4. Constraints on SME Coefficients from Lunar Laser Ranging, Very Long Baseline Interferometry, and Asteroid Orbital Dynamics

    CERN Document Server

    Poncin-Lafitte, C Le; Hees, A; Bouquillon, S; Lambert, S; Francou, G; Angonin, M -C; Bailey, Q G; Hestroffer, D; David, P; Meynadier, F; Wolf, P

    2016-01-01

    Lorentz symmetry violations can be parametrized by an effective field theory framework that contains both General Relativity and the Standard Model of particle physics, called the Standard-Model Extension or SME. We consider in this work only the pure gravitational sector of the minimal SME. We present new constraints on the SME coefficients obtained from lunar laser ranging, very long baseline interferometry, and planetary motions.

  5. Material processing with ultra-short pulse lasers working in 2μm wavelength range

    Science.gov (United States)

    Voisiat, B.; Gaponov, D.; Gečys, P.; Lavoute, L.; Silva, M.; Hideur, A.; Ducros, N.; Račiukaitis, G.

    2015-03-01

    New wavelengths of laser radiation are of interest for material processing. Results of application of the all-fiber ultrashort pulsed laser emitting in 2 µm range, manufactured by Novae, are presented. Average output power was 4.35 W in a single-spatial-mode beam centered at the 1950 nm wavelength. Pulses duration was 40 ps, and laser operated at 4.2 MHz pulse repetition rate. This performance corresponded to 25 kW of pulse peak power and almost 1 µJ in pulse energy. Material processing was performed using three different focusing lenses (100, 30 and 18 mm) and mechanical stages for the workpiece translation. 2 µm laser radiation is strongly absorbed by some polymers. Swelling of PMMA surface was observed for scanning speed above 5 mm/s using the average power of 3.45 W focused with the 30 mm lens. When scanning speed was reduced below 4 mm/s, ablation of PMMA took place. The swelling of PMMA is a consequence of its melting due to absorbed laser power. Therefore, experiments on butt welding of PMMA and overlapping welding of PMMA with other polymers were performed. Stable joint was achieved for the butt welding of two PMMA blocks with thickness of 5 mm. The laser was used to cut a Kapton film on a paper carrier with the same set-up as previous. The cut width depended on the cutting speed and focusing optics. A perfect cut with a width of 11 µm was achieved at the translation speed of 60 mm/s.

  6. Building block diode laser concept for high brightness laser output in the kW range and its applications

    Science.gov (United States)

    Ferrario, Fabio; Fritsche, Haro; Grohe, Andreas; Hagen, Thomas; Kern, Holger; Koch, Ralf; Kruschke, Bastian; Reich, Axel; Sanftleben, Dennis; Steger, Ronny; Wallendorf, Till; Gries, Wolfgang

    2016-03-01

    The modular concept of DirectPhotonics laser systems is a big advantage regarding its manufacturability, serviceability as well as reproducibility. By sticking to identical base components an economic production allows to serve as many applications as possible while keeping the product variations minimal. The modular laser design is based on single emitters and various combining technics. In a first step we accept a reduction of the very high brightness of the single emitters by vertical stacking several diodes in fast axis. This can be theoretically done until the combined fast axis beam quality is on a comparable level as the individual diodes slow axis beam quality without loosing overall beam performance after fiber coupling. Those stacked individual emitters can be wavelength stabilized by an external resonator, providing the very same feedback to each of those laser diodes which leads to an output power of about 100 W with BPP of stacking those building blocks using the very same dense spectral combing technique up to multi kW Systems without further reduction of the BPP. The 500 W building blocks are consequently designed in a way that they feature a high flexibility with regard to their emitting wavelength bandwidth. Therefore, new wavelengths can be implemented by only exchanging parts and without any additional change of the production process. This design principal theoretically offers the option to adapt the wavelength of those blocks to any applications, from UV, visible into the far IR as long as there are any diodes commercially available. This opens numerous additional applications like laser pumping, scientific applications, materials processing such as cutting and welding of copper aluminum or steel and also medical application. Typical operating at wavelengths in the 9XX nm range, these systems are designed for and mainly used in cutting and welding applications, but adapted wavelength ranges such as 793 nm and 1530 nm are also offered. Around 15

  7. Inkjet printing the three organic functional layers of two-colored organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Coenen, Michiel J.J., E-mail: Michiel.Coenen@tmc.nl [Holst Centre, PO BOX 8550, 5605 KN Eindhoven (Netherlands); Slaats, Thijs M.W.L.; Eggenhuisen, Tamara M. [Holst Centre, PO BOX 8550, 5605 KN Eindhoven (Netherlands); Groen, Pim [Holst Centre, PO BOX 8550, 5605 KN Eindhoven (Netherlands); Novel Aerospace Materials Group, Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629HS Delft (Netherlands)

    2015-05-29

    Inkjet printing allows for the roll-2-roll fabrication of organic electronic devices at an industrial scale. In this paper we demonstrate the fabrication of two-colored organic light emitting diodes (OLEDs) in which three adjacent organic device layers were inkjet printed from halogen free inks. The resulting devices demonstrate the possibilities offered by this technique for the fabrication of OLEDs for signage and personalized electronics. - Highlights: • Two-colored organic light emitting diodes with 3 inkjet printed device layers were fabricated. • All materials were printed from halogen free inks. • Inkjet printing of emissive materials is suitable for signage applications.

  8. Time biases in laser ranging observations: A concerning issue of Space Geodesy

    Science.gov (United States)

    Exertier, Pierre; Belli, A.; Lemoine, J. M.

    2017-09-01

    Time transfer by Laser Ranging (LR) recently demonstrated a remarkable stability (a few ps over ∼1000 s) and accuracy (service. The approach we investigate is to compute time synchronization between clocks used at LR stations using accurate data of the Time Transfer by Laser Link (T2L2) experiment onboard the satellite Jason-2 (Samain et al., 2014). Systematic time biases are estimated against the UTC time scale for a set of 22 observing stations in 2013, in the range of zero to a few μ s. Our results suggest that the ILRS network suffers from accuracy issues, due to time biases in the laser ranging observations. We discuss how these systematic effects impact the precise orbit determination of LAGEOS geodetic satellites over a 1-year analysis, and additionally give a measure of the local effect into station coordinates, regarding in particular the effect in the east-west component that is of 2-6 mm for a typical systematic time bias of one μ s.

  9. Reliability analysis of onboard laser ranging systems for control systems by movement of spacecraft

    Directory of Open Access Journals (Sweden)

    E. I. Starovoitov

    2014-01-01

    Full Text Available The purpose of this paper is to study and find the ways to improve the reliability of onboard laser ranging system (LRS used to control the spacecraft rendezvous and descent. The onboard LRS can be implemented with optical-mechanical scanner and without it. The paper analyses the key factors, which influence on the reliability of both LRS. Reliability of LRS is pretty much defined by the reliability of the laser source and its radiation mode. Solid-state diode-pumped lasers are primarily used as a radiation source. The radiation mode, which is defined by requirements for measurement errors of range and speed affect their reliability. The basic assumption is that the resource of solid state lasers is determined by the number pulses of pumping diodes. The paper investigates the influence of radiation mode of solid-state laser on the reliability function when measuring a passive spacecraft rendezvous dosing velocity using a differential method. With the measurement error, respectively, 10 m for range and 0.6 m/s for velocity a reliability function of 0.99 has been achieved. Reducing the measurement error of velocity to 0.5 m/s either results in reduced reliability function <0.99 or it is necessary to reduce the initial error of measurement range up to 3.5...5 m to correspond to the reliability function ≥ 0.995. For the optomechanical scanner-based LRS the maximum pulse repetition frequency versus the range has been obtained. This dependence has been used as a basis to define the reliability function. The paper investigates the influence of moving parts on the reliability of scanning LRS with sealed or unsealed optomechanical unit. As a result, it has been found that the exception of moving parts is justified provided that manufacturing the sealed optomechanical LRS unit is impossible. In this case, the reliability function increases from 0.99 to 0.9999. When sealing the opto-mechanical unit, the same increase in reliability is achieved through

  10. A Hybrid Fiber/Solid-State Regenerative Amplifier with Tunable Pulse Widths for Satellite Laser Ranging

    Science.gov (United States)

    Coyle, Barry; Poulios, Demetrios

    2013-01-01

    A fiber/solid-state hybrid seeded regenerative amplifier, capable of achieving high output energy with tunable pulse widths, has been developed for satellite laser ranging applications. The regenerative amplifier cavity uses a pair of Nd:YAG zigzag slabs oriented orthogonally to one another in order to make thermal lensing effects symmetrical and simplify optical correction schemes. The seed laser used is a fiber-coupled 1,064-nm narrowband (1 mJ) was measured. This corresponds to a nonlinear conversion efficiency of >60%. Furthermore, by pulse pumping this system, a single pulse per laser shot can be created for the SLR (satellite laser ranging) measurement, and this can be ejected into the instrument. This is operated at the precise frequency needed by the measurement, as opposed to commercial short-pulsed, mode-locked systems that need to operate in a continuous fashion, or CW (continuous wave), and create pulses at many MHz. Therefore, this design does not need to throw away or dump 99% of the laser energy to produce what is required; this system can be far smaller, more efficient, cheaper, and readily deployed in the field when packaged efficiently. Finally, by producing custom diode seed pulses electronically, two major advantages over commercial systems are realized: First, this pulse shape is customizable and not affected by the cavity length or gain of the amplifier cavity, and second, it can produce adjustable (selectable) pulse widths by simply adding multiple seed diodes and coupling each into commercial, low-cost fiber-optic combiners.

  11. Arm-Locking with the GRACE Follow-On Laser Ranging Interferometer

    CERN Document Server

    Thorpe, James Ira

    2015-01-01

    Arm-locking is a technique for stabilizing the frequency of a laser in an inter-spacecraft interferometer by using the spacecraft separation as the frequency reference. A candidate technique for future space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA), arm-locking has been extensive studied in this context through analytic models, time-domain simulations, and hardware-in-the-loop laboratory demonstrations. In this paper we show the Laser Ranging Interferometer instrument flying aboard the upcoming Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission provides an appropriate platform for an on-orbit demonstration of the arm-locking technique. We describe an arm-locking controller design for the GRACE-FO system and a series of time-domain simulations that demonstrate its feasibility. We conclude that it is possible to achieve laser frequency noise suppression of roughly two orders of magnitude around a Fourier frequency of 1Hz with conservative margins...

  12. Compact MEMS mirror based Q-switch module for pulse-on-demand laser range finders

    Science.gov (United States)

    Milanović, Veljko; Kasturi, Abhishek; Atwood, Bryan; Su, Yu; Limkrailassiri, Kevin; Nettleton, John E.; Goldberg, Lew; Cole, Brian J.; Hough, Nathaniel

    2015-02-01

    A highly compact and low power consuming Q-switch module was developed based on a fast single-axis MEMS mirror, for use in eye-safe battery-powered laser range finders The module's 1.6mm x 1.6mm mirror has cost than the traditional Electro-Optical Q-Switch. Because pulse-on-demand capability is required, resonant mirrors cannot be used to achieve the needed performance. Instead, a fast point-to-point analog single-axis tilt actuator was designed with a custom-coated high reflectance (HR) mirror to withstand the high intra-cavity laser fluence levels. The mirror is bonded on top of the MEMS actuator in final assembly. A compact MEMS controller was further implemented with the capability of autonomous on-demand operation based on user-provided digital trigger. The controller is designed to receive an external 3V power supply and a digital trigger and it consumes ~90mW during the short switching cycle and ~10mW in standby mode. Module prototypes were tested in a laser cavity and demonstrated high quality laser pulses with duration of ~20ns and energy of over 3mJ.

  13. Short Range Photoassociation of Rb2 by a high power fiber laser

    Science.gov (United States)

    Passagem, Henry; Rodriguez, Ricardo; Ventura, Paulo; Bouloufa, Nadia; Dulieu, Olivier; Marcassa, Luis

    2016-05-01

    Photoassociation has been studied using cold trapped atomic samples for the last 20 years. Due to poor Franck-Condon overlap, a free-to-bound transition followed by spontaneous decay results in a small production of electronic ground state molecules. If the photoassociation is done at short range, deeply bound ground state molecules can be formed. Optical pumping schemes can be used to populate a single state. In our experiment, we have performed trap loss spectroscopy on trapped 85 Rb atoms in a MOT using a high power fiber laser. Our single mode fiber laser (linewidth < 1 MHz) produces about 50 W, which can be tuned in the 1060-1070 nm range. Two vibrational bound states of the 0u+ potential were observed (ν = 137 and 138). The frequency positions as well as the rotational constants of these states are in good agreement with theoretical predictions. We have also measured the lifetime of a crossed optical dipole trap using such fiber laser. The lifetime on resonance is shorter than off resonance as expected. A simple theoretical model indicates that the molecules decay to deeply bound vibrational levels in the ground state. This work was supported by Fapesp and INCT-IQ.

  14. High-order harmonic generation with a two-color laser pulse

    Institute of Scientific and Technical Information of China (English)

    Luo Lao-Yong; Du Hong-Chuan; Hu Bi-Tao

    2012-01-01

    We theoretically investigate the electron dynamics of the high-order harmonics generation process by combining a near-infrared 800 nm driving pulse with a mid-infrared 2000 nm control field.We also investigate the emission time of harmonics using time-frequency analysis to illustrate the physical mechanisms of high-order harmonic generation.We calculate the ionization rate using the Ammosov-Delone-Krainov model and interpret the variations in harmonic intensity for different control field strengths and delays.We find that the width of the harmonic plateau can be extended when the control electric field is added,and a supercontinuum from 198 to 435 eV is generated,from which an isolated 61-as pulse can be directly obtained.

  15. Influence of laser scanner range measurement noise on the quantification of rock surface roughness

    Science.gov (United States)

    Khoshelham, Kourosh; Altundag, Dogan

    2010-05-01

    The roughness of rock surfaces is traditionally measured by using manual tools such as carpenter's comp and compass and disc clinometers. The manual measurements are limited to small samples at accessible parts of the rock. Terrestrial laser scanning is an attractive alternative measurement technique, which offers large coverage, high resolution, and the ability to reach inaccessible high rock faces. The application of laser scanning to the study of rock surface roughness faces a major challenge: the inherent range imprecision hinders the quantification of roughness parameters. In practice, when roughness is in millimeter scale it is often lost in the range measurement noise. The parameters derived from the data, therefore, reflect noise rather than the actual roughness of the surface. In this paper, we investigate the influence of laser scanner range measurement noise on the quantification of rock surfaces roughness. We show that measurement noise leads to the overestimation of roughness parameters. We also demonstrate the application of wavelet de-noising method to eliminating noise from laser scanner data and deriving realistic roughness parameters. A slightly metamorphosed limestone rock in the east bank of the Meuse River in southern Belgium was scanned with a Faro LS880 terrestrial laser scanner. The scanner was positioned at approximately 5 meters distance to the rock surface, and operated at the highest possible angular resolution, i.e. 0.009 degrees. The resulting point cloud contained about 1.2 million points on the rock surface with a point-spacing of 1 mm on average. According to the technical specifications of the laser scanner, the nominal range precision at a perpendicular incidence angle, which was roughly the case in our scan, is between 0.7 mm and 5.2 mm respectively for objects of 90% and 10% reflectivity at a distance of 10 m. To serve as reference roughness data were also collected manually along three profiles on the rock surface by using a

  16. A new synchronization control circuit based on FPGA for the laser range-gated imaging system

    Science.gov (United States)

    He, Shan; Li, Li; Zhou, Yan

    2009-07-01

    Synchronization control is a kernel technique of the laser range-gated (LRG) imaging system which controls the synchronization of the pulsed laser and the ICCD camera directly. It can achieve range gating effectively and improve the resolution of image precisely. Conventional control circuits which are composed of discrete components have a poor performance of anti-interference, and the transmitting signal has a bad delay which affects the conventional circuit’s precision and stabilization seriously. To solve these problems, a range-gated synchronization control circuit is designed. This circuit, which takes the advantages of FPGA’s high compact and flexibility, uses the phase-locking-loop (PLL) to multiply the global clock frequency. This design improves the precision and stabilization greatly, makes the precision up to a nanosecond level and provides a real-time selection of the values of pulse width and delays. Experiments results indicate that this circuit has a high precise and stable range-gated pulse.

  17. Testing gravity with Lunar Laser Ranging: An update on the APOLLO experiment

    Science.gov (United States)

    Battat, James; Colmenares, Nick; Davis, Rodney; Ruixue, Louisa Huang; Murphy, Thomas W., Jr.; Apollo Collaboration

    2017-01-01

    The mystery of dark energy and the incompatibility of quantum mechanics and General Relativity indicate the need for precision experimental probes of gravitational physics. The Earth-Moon-Sun system is a fertile laboratory for such tests. The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) makes optical range measurements to retro-reflectors on the Moon with one millimeter precision. These measurements of the lunar orbit enable incisive constraints on gravitational phenomena such as the Strong Equivalence Principle and dG / dt (among others). Until now, the APOLLO team had not been able to assess the accuracy of our data, in large part because known limitations to lunar range models ensure data-model residuals at the centimeter scale. To directly measure the APOLLO system timing accuracy, we have built an Absolute timing Calibration System (ACS) that delivers photons to our detector at known, stable time intervals using a pulsed fiber laser locked to a cesium frequency standard. This scheme provides real-time calibration of the APOLLO system timing, synchronous with the range measurements. We installed the calibration system in August, 2016. In this talk, we will describe the ACS design, and present present preliminary results from the ACS calibration campaign. We acknowledge the support of both NSF and NASA

  18. A new synchronization control circuit based on FPGA for the laser range-gated imaging system

    Institute of Scientific and Technical Information of China (English)

    HE Shan; LI Li; ZHOU Yan

    2009-01-01

    Synchronization control is a kernel technique of the laser range-gated (LRG) imaging system which controls the synchro-nization of the pulsed laser and the ICCD camera directly. It can achieve range gating effectively and improve the resolution of image precisely. Conventional control circuits which are composed of discrete components have a poor performance of anti-interference, and the transmitting signal has a-bad delay which affects the conventional circuit's precision and stabili-zation seriously. To solve these problems, a range-gated synchronization control circuit is designed. This circuit, which takes the advantages of FPGA's high compact and flexibility, uses the phase-locking-loop (PLL) to multiply the global clock frequency. This design improves the precision and stabilization greatly, makes the precision up to a nanosecond level and provides a real-time selection of the values of pulse width and delays. Experiments results indicate that this circuit has a high precise and stable range-gated pulse.

  19. Estimation of intra-operative brain shift using a tracked laser range scanner.

    Science.gov (United States)

    Ding, Siyi; Miga, Michael I; Thompson, Reid C; Dumpuri, Prashanth; Cao, Aize; Dawant, Benoit M

    2007-01-01

    Intra-operative brain shift limits the usefulness of image-guided neurosurgery systems (IGNS), which are based on pre-operative images. Methods that are being developed to address this problem need intra-operative measurements as input. In this work, we present an intra-operative surface shift measurement technique that relies on a tracked 3D laser range scanner. This scanner acquires both 3D range data and 2D images, which are co-registered. We compare two methods to derive displacements at every point in the field of view. The first one relies on the registration of the 2D images; the second relies on the direct 3D registration of the 3D range data. Our results, based on five data sets, show that the 2D method is preferable.

  20. Small high-speed dynamic target at close range laser active imaging system

    Science.gov (United States)

    Yao, Jun; Wang, Du-yue; Zhang, Zheng; Zhang, Yue; Dai, Qin

    2016-11-01

    In the shooting range measuring, all-weather, high speed, unattended, the new concepts such as the remote control is gradually applied. In this paper, a new type of low cost range measurement system, using FPGA + MCU as electronic control system of laser active illumination and high-speed CMOS camera, data to the rear zone by using optical fiber communications, transmission and realizes the remote control of unmanned, due to the low cost of front-end equipment, can be used as consumables replacement at any time, combined with distributed layout principle, can maximum limit close to the measured with mutilate ability goal, thus to achieve the goal of small high-speed dynamic imaging from close range.

  1. The laser ranging experiment of the Lunar Reconnaissance Orbiter: Five years of operations and data analysis

    Science.gov (United States)

    Mao, Dandan; McGarry, Jan F.; Mazarico, Erwan; Neumann, Gregory A.; Sun, Xiaoli; Torrence, Mark H.; Zagwodzki, Thomas W.; Rowlands, David D.; Hoffman, Evan D.; Horvath, Julie E.; Golder, James E.; Barker, Michael K.; Smith, David E.; Zuber, Maria T.

    2017-02-01

    We describe the results of the Laser Ranging (LR) experiment carried out from June 2009 to September 2014 in order to make one-way time-of-flight measurements of laser pulses between Earth-based laser ranging stations and the Lunar Reconnaissance Orbiter (LRO) orbiting the Moon. Over 4,000 h of successful LR data are obtained from 10 international ground stations. The 20-30 cm precision of the full-rate LR data is further improved to 5-10 cm after conversion into normal points. The main purpose of LR is to utilize the high accuracy normal point data to improve the quality of the LRO orbits, which are nominally determined by the radiometric S-band tracking data. When independently used in the LRO precision orbit determination process with the high-resolution GRAIL gravity model, LR data provide good orbit solutions, with an average difference of ∼50 m in total position, and ∼20 cm in radial direction, compared to the definitive LRO trajectory. When used in combination with the S-band tracking data, LR data help to improve the orbit accuracy in the radial direction to ∼15 cm. In order to obtain highly accurate LR range measurements for precise orbit determination results, it is critical to closely model the behavior of the clocks both at the ground stations and on the spacecraft. LR provides a unique data set to calibrate the spacecraft clock. The LRO spacecraft clock is characterized by the LR data to a timing knowledge of 0.015 ms over the entire 5 years of LR operation. We here present both the engineering setup of the LR experiments and the detailed analysis results of the LR data.

  2. Corner-cube retro-reflector instrument for advanced lunar laser ranging

    CERN Document Server

    Turyshev, Slava G; Folkner, William M; Gutt, Gary M; Baran, Richard T; Hein, Randall C; Somawardhana, Ruwan P; Lipa, John A; Wang, Suwen

    2012-01-01

    Lunar laser ranging (LLR) has made major contributions to our understanding of the Moon's internal structure and the dynamics of the Earth-Moon system. Because of the recent improvements of the ground-based laser ranging facilities, the present LLR measurement accuracy is limited by the retro-reflectors currently on the lunar surface, which are arrays of small corner-cubes. Because of lunar librations, the surfaces of these arrays do not, in general, point directly at the Earth. This effect results in a spread of arrival times, because each cube that comprises the retroreflector is at a slightly different distance from the Earth, leading to the reduced ranging accuracy. Thus, a single, wide aperture corner-cube could have a clear advantage. In addition, after nearly four decades of successful operations the retro-reflectors arrays currently on the Moon started to show performance degradation; as a result, they yield still useful, but much weaker return signals. Thus, fresh and bright instruments on the lunar ...

  3. A review of the lunar laser ranging technique and contribution of timing systems

    Directory of Open Access Journals (Sweden)

    Cilence Munghemezulu

    2016-03-01

    Full Text Available The lunar laser ranging (LLR technique is based on the two-way time-of-flight of laser pulses from an earth station to the retroreflectors that are located on the surface of the moon. We discuss the ranging technique and contribution of the timing systems and its significance in light of the new LLR station currently under development by the Hartebeesthoek Radio Astronomy Observatory (HartRAO. Firstly, developing the LLR station at HartRAO is an initiative that will improve the current geometrical network of the LLR stations which are presently concentrated in the northern hemisphere. Secondly, data products derived from the LLR experiments � such as accurate lunar orbit, tests of the general relativity theory, earth-moon dynamics, interior structure of the moon, reference frames, and station position and velocities � are important in better understanding the earth-moon system. We highlight factors affecting the measured range bias such as the effect of earth tides on station position and delays induced by timing systems, as these must be taken into account during the development of the LLR analysis software. HartRAO is collocated with other fundamental space geodetic techniques which makes it a true fiducial geodetic site in the southern hemisphere and a central point for further development of space-based techniques in Africa. Furthermore, the new LLR will complement the existing techniques by providing new niche areas of research both in Africa and internationally.

  4. Study on the backscattered light intensity to airborne laser range-gated imaging

    Science.gov (United States)

    Wang, Ling; Yu, Lei; Kou, Tian; Wu, Xueming

    2016-10-01

    Based on the range-gated technology in the application of airborne laser detection imaging system, sequence relations of the parameters in the model of range gating in detail was analyzed. The effective scope of atmospheric backscatter and the moment before or after pulsing of the unit section was obtained. Horizontal range-gated imaging model was established and the calculation method of backscattered light intensity was given. Then slant distance detection of airborne laser active imaging was revised. By the object-image relation of points on the scattering section, the light path diagram of imaging detection system was built and the corresponding relation of light intensity between scattering points and receiving points was given. The variation regularity and distribution of light intensity on the detector under horizontal and slant detection were gained. Under the idea, the outfield testing platform was set up, and the relative error of data between measured and simulated results was controlled within 5%. The two kinds of data achieved a good coincident, which demonstrated the effectiveness of the built model. The two kinds of data achieved a good coincident, which demonstrated the effectiveness of the built model.

  5. Method to simulate the object tracking with photon-counting laser ranging system

    Science.gov (United States)

    Du, Xian; Xing, JiChuan; Huang, Hao

    2015-11-01

    We provide a new method to simulate the process of tracking the noncooperative object that moves beyond visual range with a photon-counting laser ranging system. Based on fundamentals of photon-counting laser ranging techniques and parameters of the experimental prototype, we generate echo events according to their probability. Then, we accumulate the echo data in a certain period of time and accurately extract the object's trajectory with mean-shift and random sample consensus algorithms. Depending on the trajectory during the accumulation period, we predict the relative movement of the object in succeeding cycles by using self-tuning α-β filtering and carefully pick out photon echo signals and apply the polynomial fitting to them to compute the trajectory of the object. The simulation shows that the error between the theoretical trajectory and the extracted trajectory is decreasing all the time, which suggests that we can track the object precisely as the time goes by. The simulation in this paper provides a new way for applications like satellite orientation, identification, troubleshooting, etc.

  6. Application of Laser Ranging and VLBI Data to a Study of Plate Tectonic Driving Forces

    Science.gov (United States)

    Solomon, S. C.

    1980-01-01

    The conditions under which changes in plate driving or resistive forces associated with plate boundary earthquakes are measurable with laser ranging or very long base interferometry were investigated. Aspects of plate forces that can be characterized by such measurements were identified. Analytic solutions for two dimensional stress diffusion in a viscoelastic plate following earthquake faulting on a finite fault, finite element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting, and quantitative constraints from modeling of global intraplate stress on the magnitude of deviatoric stress in the lithosphere are among the topics discussed.

  7. Testing fundamental physics with laser ranged satellites: perspectives and goals of the LARASE experiment

    Science.gov (United States)

    Lucchesi, David; Anselmo, Luciano; Pardini, Carmen; Peron, Roberto; Pucacco, Giuseppe; Visco, Massimo

    Passive laser-ranged satellites, launched for geodynamics and geophysics purposes, not only have contributed to significant measurements in space geodesy that enabled, among several aspects, a deeper knowledge of the Earth's geopotential (both in its static and dynamic behavior), as well as of the geocenter motion and GM value up to the definition of the terrestrial reference frame, but they also provided an outstanding test bench to fundamental physics, as in the case of the first measurement of the Lense-Thirring precession on the combined nodes of the two LAGEOS satellites, or in the case of the total relativistic precession of the argument of pericenter of LAGEOS II. Indeed, the physical characteristics of such satellites -- such as their low area-to-mass ratio -- as well as those of their orbits, and the availability of high-quality tracking data provided by the International Laser Ranging Service (ILRS), allow for precise tests of gravitational theories. The aim of LARASE (LAser RAnged Satellites Experiment) is to go a step further in the tests of the gravitational interaction in the field of Earth, i.e. in the weak-field and-slow motion limit of general relativity, by the joint analysis of the orbits of the two LAGEOS satellites and that of the most recent LARES satellite. One of the key ingredients to reach such a goal is to provide high-quality updated models for the perturbing non-gravitational forces acting on the surface of such satellites. A large amount of Satellite Laser Ranging (SLR) data of LAGEOS and LAGEOS II has been analyzed using a set of dedicated models for satellite dynamics, and the related post-fit residuals have been analyzed. A parallel work is on-going in the case of LARES that, due to its much lower altitude, is subject to larger gravitational and non-gravitational effects; the latter are mitigated in part by its much lower area-to-mass ratio. Recent work on the data analysis of the orbit of such satellites will be presented together

  8. Multidiagnostics analysis of ion dynamics in ultrafast laser ablation of metals over a large fluence range

    Energy Technology Data Exchange (ETDEWEB)

    Anoop, K. K.; Polek, M. P.; Bruzzese, R.; Amoruso, S.; Harilal, Sivanandan S.

    2015-02-28

    The ions dynamics in ultrafast laser ablation of metals is studied over a fluence range spanning from the ablation threshold up to ~75 J/cm2 by means of three established diagnostic techniques. Langmuir probe, Faraday cup and spectrally resolved ICCD imaging simultaneously monitor the laser-produced plasma ions produced during ultrafast laser ablation of a copper target. The fluence dependence of ion yield is analyzed observing the occurrence of three different regimes. Moreover, the specific ion yield shows a maximum at about 4-5 J/cm2, followed by a gradual reduction and a transition to a high-fluence regime above ~50 J/cm2. The fluence variation of the copper ions angular distribution is also analyzed, observing a gradual increase of forward peaking of Cu ions for fluences up to ~10 J/cm2. Then, a broader ion component is observed at larger angles for fluences larger than ~10 J/cm2. Finally, an experimental characterization of the ions angular distribution for several metallic targets (Mg, Al, Cr, Fe, Cu, and W) is carried out at a relatively high fluence of ~66 J/cm2. Interestingly, the ion emission from the volatile metals show a narrow forward peaked distribution and a high peak ion yield compared to the refractory metals. Moreover, the width of ion angular distributions presents a striking correlation with the peak ion yield.

  9. Centimeter Accuracy for the French Transportable Laser Ranging Station (FTLRS) through Sub-System Controls

    Science.gov (United States)

    Nicolas, J.; Pierron, F.; Samain, E.; Barlier, F.

    The French Transportable Laser Ranging Station (FTLRS)is a highly mobile satellite laserranging (SLR) system dedicated to the trackingof geodetic satellites equipped withretroreflectors. This station weighs only 300kg witha 13-cm diameter telescope and is housedin eight containers.The reliability of such a station and its accuracy of 2 cmin real field experiment conditionswere demonstrated during a first field campaign carried outfrom October 1996 to February1997 near Ajaccio on Corsica Island, France. The results ofthis probatory experiment suggestedthat several technical improvements and some modificationswere necessary for JASON-1validation and calibration phase and for new applicationssuch as the Time Transfer by LaserLink (T2L2) experiment. A first change concerns theuse of a new laser wavelength (green instead ofinfrared) and of a new avalanche photodiode with atime walk compensation system. Anotherchange is the installation of a coaxial cabletransmitting directly the signal coming from thereturn detector. Finally, a new calibration systemwas developed with several other changes.A short description of the system is first given.Then, the major changes and the main resultsof ground accuracy tests are summarized and presented.

  10. Narrow-line external cavity diode laser micro-packaging in the NIR and MIR spectral range

    Science.gov (United States)

    Jiménez, A.; Milde, T.; Staacke, N.; Aßmann, C.; Carpintero, G.; Sacher, J.

    2017-07-01

    Narrow-linewidth tunable diode lasers are an important tool for spectroscopic instrumentation. Conventional external cavity diode lasers offer high output power and narrow linewidth. However, most external cavity diode lasers are designed as laboratory instrument and do not allow portability. In comparison, other commonly used lasers, like distributed feedback lasers (DFB) that are capable of driving a handheld device, are limited in power and show linewidths which are not sufficiently narrow for certain applications. We present new miniaturized types of tunable external cavity diode laser which overcome the drawbacks of conventional external cavity diode lasers and which preserve the advantages of this laser concept. Three different configurations are discussed in this article. The three types of miniaturized external cavity diode laser systems achieve power values of more than 50 mW within the 1.4 μm water vapor absorption band with excellent side-mode suppression and linewidth below 100 kHz. Typical features outstand with respect to other type of laser systems which are of extended use such as DFB laser diodes. The higher output power and the lower linewidth will enable a higher sensitivity and resolution for a wide range of applications.

  11. Application of a long-range terrestrial laser scanner in research on lowland geodynamic processes

    Science.gov (United States)

    Wiśniewska, Daria; Kramkowski, Mateusz; Tyszkowski, Sebastian

    2015-04-01

    Progress in the LIDAR technology allows collection of data over a longer range and with a higher precision than most of geodetic measurement methods. It is particularly useful in areas that are inaccessible, dangerous, or with a highly variable morphology. These include mountains, steep slopes of river valleys, and edges of water bodies. Because of a high variation in altitude, they are particularly prone to geodynamic processes. In recent years, such areas have been surveyed more and more often with the use of Airborne Laser Scanning, but the high costs and low frequency of surveys make it difficult to trace the dynamics of phenomena and recorded processes. A few years ago, a new method for imaging of land surfaces started to be used: Terrestrial Laser Scanning. The latest scanners make long-distance scanning possible, up to several kilometres), which until recently had been reserved exclusively for Airborne Laser Scanning. The ease and mobility of scanning allows recording of geodynamic processes immediately after their initiation and their constant monitoring, with a high frequency of data collection. The usefulness of long-distance Terrestrial Laser Scanning is presented here on the basis of mass movements on slopes of a large river valley (the lower Vistula valley) and edges of artificial water bodies. These areas were selected because of a high dynamics of geodynamic processes. The scanning was performed at a distance of 2-4 km from the objects, with a resolution of 0.002°. Such parameters of the equipment and the broad scope and long range enable researchers simultaneous scanning of wide belts of the marginal zone. They also allow precise imaging of slopes, including the microforms that cannot be recorded with any other method. Thanks to the characteristics of laser beam reflection, it is also possible to perform analyses that allow identification of landslide initiation, as well as initial stages of erosion of river banks and edges of water bodies. In this

  12. Assessment of long-range kinematic GPS positioning errors by comparison with airborne laser altimetry and satellite altimetry

    DEFF Research Database (Denmark)

    Zhang, X.H.; Forsberg, René

    2007-01-01

    Long-range airborne laser altimetry and laser scanning (LIDAR) or airborne gravity surveys in, for example, polar or oceanic areas require airborne kinematic GPS baselines of many hundreds of kilometers in length. In such instances, with the complications of ionospheric biases, it can be a real c...

  13. Laser parameters of a Fe : ZnSe crystal in the 85-255-K temperature range

    NARCIS (Netherlands)

    Voronov, AA; Kozlovskii, [No Value; Korostelin, YV; Podmar'kov, YP; Frolov, MP

    The temperature dependence of the efficiency of a laser based on a Fe:ZnSe crystal grown from the vapour phase by the free-growth method is studied in the 85-255-K temperature range. As the temperature was increased, the slope efficiency of the laser with respect to absorbed energy decreased from

  14. MOONLIGHT: A NEW LUNAR LASER RANGING RETROREFLECTOR AND THE LUNAR GEODETIC PRECESSION

    Directory of Open Access Journals (Sweden)

    M. Martini

    2013-12-01

    Full Text Available Since the 1970s Lunar Laser Ranging (LLR to the Apollo Cube Corner Retroreflector (CCR arrays (developed by the University of Maryland, UMD supplied almost all significant tests of General Relativity (Alley et al., 1970; Chang et al., 1971; Bender et al.,1973: possible changes in the gravitational constant, gravitational self-energy, weak equivalence principle, geodetic precession, inverse-square force-law. The LNF group, in fact, has just completed a new measurement of the lunar geodetic precession with Apollo array, with accuracy of 9 × 10−3, comparable to the best measurement to date. LLR has also provided significant information on the composition and origin of the moon. This is the only Apollo experiment still in operation. In the 1970s Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo CCR arrays dominate the error budget. With the project MoonLIGHT (Moon Laser Instrumentation for General relativity High-accuracy Tests, in 2006 INFN-LNF joined UMD in the development and test of a new-generation LLR payload made by a single, large CCR (100mm diameter unaffected by the effect of librations. With MoonLIGHT CCRs the accuracy of the measurement of the lunar geodetic precession can be improved up to a factor 100 compared to Apollo arrays. From a technological point of view, INFN-LNF built and is operating a new experimental apparatus (Satellite/lunar laser ranging Characterization Facility, SCF and created a new industry-standard test procedure (SCF-Test to characterize and model the detailed thermal behavior and the optical performance of CCRs in accurately laboratory-simulated space conditions, for industrial and scientific applications. Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP and the

  15. Feasibility Study of Interstellar Missions Using Laser Sail Probes Ranging in Size from the Nano to the Macro

    Science.gov (United States)

    Malroy, Eric T.

    2010-01-01

    This paper presents the analysis examining the feasibility of interstellar travel using laser sail probes ranging in size from the nano to the macro. The relativistic differential equations of motion for a laser sail are set up and solved using the Pasic Method. The limitations of the analysis are presented and discussed. The requirements for the laser system are examined, including the thermal analysis of the laser sails. Black holes, plasma fields, atmospheric collisions and sun light are several methods discussed to enable the deceleration of the interstellar probe. A number of novel mission scenarios are presented including the embryonic transport of plant life as a precursor to the arrival of space colonies

  16. Broad-range self-sweeping of a narrow-line self-pulsing Yb-doped fiber laser

    Science.gov (United States)

    Lobach, Ivan A.; Kablukov, Sergey I.; Podivilov, Evgeniy V.; Babin, Sergey A.

    2011-08-01

    The effect of broad-range (16 nm) self-sweeping of a narrow-line (less than 1 pm) Yb-doped fiber laser has been demonstrated experimentally. It is found that the effect arises from the self-sustained relaxation oscillations. As a result, the sweeping rate increases as square root of the laser power and decreases with increasing cavity length. Based on these results we propose a model describing dynamics of the laser frequency. The model takes into account the effects of gain saturation at the laser transition and spatial hole burning in the self-pulsing regime.

  17. OBSTACLE DETECTION BY ALV USING TWO 2D LASER RANGE FINDERS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper describes an effective method of obstacle detection by ALV (Autonomous Land Vehi- cle) equipped with two 2D laser range finders (LRF) installed at different locations of the ALV to obtain eom- prehensive information on the environment. The data processing includes two main steps: ( 1 ) data-processing of the current sample; (2) fusion of the former range data and the current one. The rough description of the ALV's environnent via the four sub-steps ( Data Filter, Obstacle Extraction, Obstacle Merging, Distinguish- ing Obstacle from Road-Edge) was not reliable enough for our control system. To overcome the shortcoming of the 2D LRF and the motion noise of the ALV, a Kalman filter was used to estimate the position of the obsta- cles; then the data of the two LRFs were collated to obtain the height and width of the obstacles. Experiment results attested the feasibility of the detection system.

  18. Large-Scale Hollow Retroreflectors for Lunar Laser Ranging at Goddard Space Flight Center

    Science.gov (United States)

    Preston, Alix

    2012-01-01

    Laser ranging to the retroreflector arrays placed on the lunar surface by the Apollo astronauts and the Soviet Luna missions have dramatically increased our understanding of gravitational physics along with Earth and Moon geophysics, geodesy, and dynamics. Although the precision of the range measurements has historically been limited by the ground station capabilities, advances in the APOLLO instrument at the Apache Point facility in New Mexico is beginning to be limited by errors associated with the lunar arrays. We report here on efforts at Goddard Space Flight Center to develop the next generation of lunar retroreflectors. We will describe a new facility that is being used to design, assemble, and test large-scale hollow retroreflectors. We will also describe results from investigations into various bonding techniques used to assemble the open comer cubes and mirror coatings that have dust mitigation properties.

  19. Large-Scale Hollow Retroreflectors for Lunar Laser Ranging at Goddard Space Flight Center

    Science.gov (United States)

    Preston, Alix M.

    2012-05-01

    Laser ranging to the retroreflector arrays placed on the lunar surface by the Apollo astronauts and the Soviet Luna missions have dramatically increased our understanding of gravitational physics along with Earth and Moon geophysics, geodesy, and dynamics. Although the precision of the range measurements has historically been limited by the ground station capabilities, advances in the APOLLO instrument at the Apache Point facility in New Mexico is beginning to be limited by errors associated with the lunar arrays. We report here on efforts at Goddard Space Flight Center to develop the next generation of lunar retroreflectors. We will describe a new facility that is being used to design, assemble, and test large-scale hollow retroreflectors. We will also describe results from investigations into various bonding techniques used to assemble the open corner cubes and mirror coatings that have dust mitigation properties.

  20. Laser ranging by time-of-flight measurement of femtosecond light pulses

    Science.gov (United States)

    Kim, Young-Jin

    2014-04-01

    Time-of-flight (TOF) measurement of femtosecond light pulses was investigated for laser ranging of long distances with sub-micrometer precision in the air. The bandwidth limitation of the photo-detection electronics used in timing femtosecond pulses was overcome by adopting a type-II nonlinear second-harmonic crystal that permits producing the balanced optical cross-correlation signal between two overlapped light pulses. This method offered a sub-femtosecond timing resolution in determining the temporal offset between two pulses through lock-in control of the pulse repetition rate with reference to the atomic clock. The exceptional ranging capability was verified by measuring various distances from 1.5 m to 700 m. This method is found suited for terrestrial land surveying and space missions of formation-flying satellites.

  1. High precision laser ranging by time-of-flight measurement of femtosecond pulses

    Science.gov (United States)

    Lee, Joohyung; Lee, Keunwoo; Lee, Sanghyun; Kim, Seung-Woo; Kim, Young-Jin

    2012-06-01

    Time-of-flight (TOF) measurement of femtosecond light pulses was investigated for laser ranging of long distances with sub-micrometer precision in the air. The bandwidth limitation of the photo-detection electronics used in timing femtosecond pulses was overcome by adopting a type-II nonlinear second-harmonic crystal that permits the production of a balanced optical cross-correlation signal between two overlapping light pulses. This method offered a sub-femtosecond timing resolution in determining the temporal offset between two pulses through lock-in control of the pulse repetition rate with reference to the atomic clock. The exceptional ranging capability was verified by measuring various distances of 1.5, 60 and 700 m. This method is found well suited for future space missions based on formation-flying satellites as well as large-scale industrial applications for land surveying, aircraft manufacturing and shipbuilding.

  2. A high sensitive 66 dB linear dynamic range receiver for 3-D laser radar

    Science.gov (United States)

    Ma, Rui; Zheng, Hao; Zhu, Zhangming

    2017-08-01

    This study presents a CMOS receiver chip realized in 0.18 μm standard CMOS technology and intended for high precision 3-D laser radar. The chip includes an adjustable gain transimpedance pre-amplifier, a post-amplifier and two timing comparators. An additional feedback is employed in the regulated cascode transimpedance amplifier to decrease the input impedance, and a variable gain transimpedance amplifier controlled by digital switches and analog multiplexer is utilized to realize four gain modes, extending the input dynamic range. The measurement shows that the highest transimpedance of the channel is 50 k {{Ω }}, the uncompensated walk error is 1.44 ns in a wide linear dynamic range of 66 dB (1:2000), and the input referred noise current is 2.3 pA/\\sqrt{{Hz}} (rms), resulting in a very low detectable input current of 1 μA with SNR = 5.

  3. Satellite laser ranging measurements in South Africa: Contributions to earth system sciences

    Directory of Open Access Journals (Sweden)

    Christina M. Botai

    2015-03-01

    Full Text Available This contribution reassesses progress in the development of satellite laser ranging (SLR technology and its scientific and societal applications in South Africa. We first highlight the current global SLR tracking stations within the framework of the International Laser Ranging Service (ILRS and the artificial satellites currently being tracked by these stations. In particular, the present work focuses on analysing SLR measurements at Hartebeesthoek Radio Astronomy Observatory (HartRAO, South Africa, based on the MOBLAS-6 SLR configuration. Generally, there is a weak geometry of ILRS stations in the southern hemisphere and the SLR tracking station at HartRAO is the only active ILRS station operating on the African continent. The SLR-derived products such as station positions and velocities, satellite orbits, components of earth's gravity field and their temporal variations, earth orientation parameters are collected, merged, achieved and distributed by the ILRS under the Crustal Dynamic Data Information System. These products are used in various research fields such as detection and monitoring of tectonic plate motion, crustal deformation, earth rotation, polar motion, and the establishment and monitoring of International Terrestrial Reference Frames, as well as modelling of the spatio-temporal variations of the earth's gravity field. The MOBLAS-6 tracking station is collocated with other geodetic techniques such as very long baseline interferometry and Global Navigation Satellite Systems, thus making this observatory a fiducial geodetic location. Some applications of the SLR data products are described within the context of earth system science.

  4. First successful satellite laser ranging with a fibre-based transmitter

    Science.gov (United States)

    Hampf, D.; Sproll, F.; Wagner, P.; Humbert, L.; Hasenohr, T.; Riede, W.

    2016-08-01

    Satellite laser ranging (SLR) is an established technology used for geodesy, fundamental science and precise orbit determination. This paper reports on the first successful SLR measurement from the German Aerospace Center research observatory in Stuttgart. While many SLR stations are in operation, the experiment described here is unique in several ways: The modular system has been assembled completely from commercial off-the-shelf components, which increases flexibility and significantly reduces hardware costs. To our knowledge it has been the first time that an SLR measurement has been conducted using an optical fibre rather than a coudé path to direct the light from the laser source onto the telescope. The transmitter operates at an output power of about 75 mW and a repetition rate of 3 kHz, and at a wavelength of 1064 nm. Due to its rather small diameter of only 80 μm, the receiver detector features a low noise rate of less than 2 kHz and can be operated without gating in many cases. With this set-up, clear return signals have been received from several orbital objects equipped with retroreflectors. In its current configuration, the system does not yet achieve the same performance as other SLR systems in terms of precision, maximum distance and the capability of daylight ranging; however, plans to overcome these limitations are outlined.

  5. APPLICATION OF TWO-COLOR INTERPHASE FISH USING SEX PROBE IN ALLOGENEIC STEM CELL TRANSPLANTATION

    Institute of Scientific and Technical Information of China (English)

    曾慧兰; 李建勇; 朱康儿; 薛永权; 李杨秋; 刘晓力; 过宇

    2002-01-01

    Objective: To evaluate the significance of two-color interphase fluorescence in situ hybridization (FISH) using X and Y centromere probe in the engraftment estimation and minimal residual disease (MRD) monitoring after allogeneic stem cell transplantation (alloSCT). Methods: Samples from 12 cases patients in different periods after alloSCT were detected by interphase FISH. Results: All of the 12 patients were proved to obtain engraftment 22(35 days after alloSCT. While traditional karyotype showed as 100%XX or 100%XY invariably, FISH showed different percentages of donor original sex chromosome. Conclusion: Two-color interphase FISH is a more sensitive and simple test for engraftment evaluation and MRD monitoring post SCT, though, it can not entirely replace traditional karyotype analysis and gene detection by RT-PCR.

  6. Effects of a static electric field on two-color photoassociation of heteronuclear atom-pairs

    CERN Document Server

    Chakraborty, Debashree

    2013-01-01

    We study non-perturbative effects of a static electric field on two-color photoassociation of heteronuclear atom-pairs. A static electric field induces anisotropy in scattering between two heteronuclear atoms and hybridizes field-free rotational states of heteronuclear dimers or polar molecules. In a previous paper [D. Chakraborty $\\it {et.}$ $\\it {al.}$, J. Phys. B 44, 095201 (2011)], the effects of a static electric field on one-color photoassociation between heteronuclear atoms has been described through field-modified ground-state scattering states, neglecting electric field effects on heteronuclear diatomic bound states. To study the effects of a static electric field on heteronuclear bound states, and the resulting influence on Raman-type two-color photoassociation between heteronuclear atoms in the presence of a static electric field, we develop a non-perturbative numerical method to calculate static electric field-dressed heteronuclear bound states. We show that the static electric field induced scatt...

  7. Femtosecond Non-degenerate Four Wave Mixing Spectroscopy: The Two Color Photon Echo Peak Shift

    CERN Document Server

    Prall, B S

    2005-01-01

    The couplings between multiple electronic states and electronic and nuclear coordinates are examined for condensed phase systems by femtosecond degenerate and non-degenerate four wave mixing. The two-color photon echo peak shift experiment is developed which allows measurement of the correlation between transition frequencies in two different spectral regions. Two-color photon echo peak shift (2C3PEPS) experiments are used to study coupling between electronic states in the lutetium bisphthalocyanine anion, LuPc2−. Electronically induced mixing between exciton and charge resonance states leads to correlations in transition energies for the two observed transitions. This correlation generates non-zero 2C3PEPS which, when compared with 1C3PEPS, allows experimental determination of the degree of mixing, which was in good agreement with theoretical predictions. By exploiting a coherently excited nuclear wavepacket, the nuclear dependence on the electronic mixing between exciton and charge resonance state...

  8. Two-color mid-infrared thermometer with a hollow glass optical fiber.

    Science.gov (United States)

    Small, W; Celliers, P M; Da Silva, L B; Matthews, D L; Soltz, B A

    1998-10-01

    We have developed a low-temperature optical-fiber-based two-color infrared thermometer. A single 700-mum-bore hollow glass optical fiber collects and transmits radiation that is then modulated and split into two paths by a reflective optical chopper. Two different thermoelectrically cooled mid-infrared HgCdZnTe photoconductors monitor the chopped signals that are recovered with lock-in amplification. With the two previously obtained blackbody calibration equations, a computer algorithm calculates the true temperature and emissivity of a target in real time, taking into account reflection of the ambient radiation field from the target surface. The small numerical aperture of the hollow glass fiber and the fast response of the detectors, together with the two-color principle, permit high spatial and temporal resolution while allowing the user to dynamically alter the fiber-to-target distance.

  9. Dirac Spectrum of the Wilson Dirac Operator for QCD with Two Colors

    CERN Document Server

    Kieburg, Mario; Zafeiropoulos, Savvas

    2015-01-01

    We study the lattice artefacts of the Wilson Dirac operator for QCD with two colors and fermions in the fundamental representation from the viewpoint of chiral perturbation theory. These effects are studied with the help of the following spectral observables: the level density of the Hermitian Wilson Dirac operator, the distribution of chirality over the real eigenvalues, and the chiral condensate for the quenched as well as for the unquenched theory. We provide analytical expressions for all these quantities. Moreover we derive constraints for the level density of the real eigenvalues of the non-Hermitian Wilson Dirac operator and the number of additional real modes. The latter is a good measure for the strength of lattice artefacts. All computations are confirmed by Monte Carlo simulations of the corresponding random matrix theory which agrees with chiral perturbation theory of two color QCD with Wilson fermions.

  10. Corner-cube retro-reflector instrument for advanced lunar laser ranging

    Science.gov (United States)

    Turyshev, Slava G.; Williams, James G.; Folkner, William M.; Gutt, Gary M.; Baran, Richard T.; Hein, Randall C.; Somawardhana, Ruwan P.; Lipa, John A.; Wang, Suwen

    2013-08-01

    Lunar laser ranging (LLR) has made major contributions to our understanding of the Moon's internal structure and the dynamics of the Earth-Moon system. Because of the recent improvements of the ground-based laser ranging facilities, the present LLR measurement accuracy is limited by the retro-reflectors currently on the lunar surface, which are arrays of small corner-cubes. Because of lunar librations, the surfaces of these arrays do not, in general, point directly at the Earth. This effect results in a spread of arrival times, because each cube that comprises the retroreflector is at a slightly different distance from the Earth, leading to the reduced ranging accuracy. Thus, a single, wide aperture corner-cube could have a clear advantage. In addition, after nearly four decades of successful operations the retro-reflectors arrays currently on the Moon started to show performance degradation; as a result, they yield still useful, but much weaker return signals. Thus, fresh and bright instruments on the lunar surface are needed to continue precision LLR measurements. We have developed a new retro-reflector design to enable advanced LLR operations. It is based on a single, hollow corner cube with a large aperture for which preliminary thermal, mechanical, and optical design and analysis have been performed. The new instrument will be able to reach an Earth-Moon range precision of 1-mm in a single pulse while being subjected to significant thermal variations present on the lunar surface, and will have low mass to allow robotic deployment. Here we report on our design results and instrument development effort.

  11. Range accuracy of photon heterodyne detection with laser pulse based on Geiger-mode APD.

    Science.gov (United States)

    Luo, Hanjun; Yuan, XiuHua; Zeng, Yanan

    2013-08-12

    In this paper, we propose a combined system of heterodyne detection with laser pulse and photon counting based on Geiger-mode avalanche photodiode (GM-APD) that is designed to achieve the range of remote non-cooperative target. Based on the heterodyne principle and assuming that the creation of primary electrons in GM-APD is Poisson-distributed, the range accuracy model is established. The factors that influence the range accuracy, namely pulse width, echo intensity, local oscillator (LO) intensity, noise, echo position, and beat frequency, are discussed. The results show that these six factors have significant influence on the range accuracy when the echo intensity is extremely weak. In case that the primary electrons of the echo signal are beyond 4, the pulse width and echo intensity are the main influence factors. It is also shown that the stronger echo intensity, narrower pulse width, low noise, large echo position, and small beat frequency produce higher range accuracy in a pulsed photon heterodyne detection system based on GM-APD.

  12. Experiments and error analysis of laser ranging based on frequency-sweep polarization modulation

    Science.gov (United States)

    Gao, Shuyuan; Ji, Rongyi; Li, Yao; Cheng, Zhi; Zhou, Weihu

    2016-11-01

    Frequency-sweep polarization modulation ranging uses a polarization-modulated laser beam to determine the distance to the target, the modulation frequency is swept and frequency values are measured when transmitted and received signals are in phase, thus the distance can be calculated through these values. This method gets much higher theoretical measuring accuracy than phase difference method because of the prevention of phase measurement. However, actual accuracy of the system is limited since additional phase retardation occurs in the measuring optical path when optical elements are imperfectly processed and installed. In this paper, working principle of frequency sweep polarization modulation ranging method is analyzed, transmission model of polarization state in light path is built based on the theory of Jones Matrix, additional phase retardation of λ/4 wave plate and PBS, their impact on measuring performance is analyzed. Theoretical results show that wave plate's azimuth error dominates the limitation of ranging accuracy. According to the system design index, element tolerance and error correcting method of system is proposed, ranging system is built and ranging experiment is performed. Experiential results show that with proposed tolerance, the system can satisfy the accuracy requirement. The present work has a guide value for further research about system design and error distribution.

  13. Autler-Townes splitting in two-color photoassociation of 6Li

    CERN Document Server

    Schloeder, U; Silber, C; Zimmermann, C; Schloeder, Ulrike; Deuschle, Thomas; Silber, Christian; Zimmermann, Claus

    2003-01-01

    We report on high-resolution two-color photoassociation spectroscopy in the triplet system of magneto-optically trapped 6Li. The absolute transition frequencies have been measured. Strong optical coupling of the bound molecular states has been observed as Autler-Townes splitting in the photoassociation signal. The spontaneous bound-bound transition rate is determined and the molecule formation rate is estimated. The observed lineshapes are in good agreement with the theoretical model.

  14. Lowest eigenvalues of the Dirac operator for two color QCD at finite density

    CERN Document Server

    Bittner, E; Markum, H; Pullirsch, R; Bittner, Elmar; Lombardo, Maria-Paola; Markum, Harald; Pullirsch, Rainer

    2001-01-01

    We investigate the eigenvalue spectrum of the staggered Dirac matrix in full QCD with two colors and finite chemical potential. Along the strong-coupling axis up to the temperature phase transition, the low-lying Dirac spectrum is well described by random matrix theory (RMT) and exhibits universal behavior. The situation is discussed in the chirally symmetric phase and no universality is seen for the microscopic spectral density.

  15. Polyakov-Quark-Meson-Diquark Model for two-color QCD

    CERN Document Server

    Strodthoff, Nils

    2013-01-01

    We present an update on the phase diagram of two-color QCD from a chiral effective model approach based on a quark-meson-diquark model using the Functional Renormalization Group (FRG). We discuss the impact of perturbative UV contributions, the inclusion of gauge field dynamics via a phenomenological Polyakov loop potential, and the impact of matter backcoupling on the gauge sector. The corresponding phase diagram including these effects is found to be in qualitative agreement with recent lattice investigations.

  16. Testing relativity again, laser, laser, laser, laser

    NARCIS (Netherlands)

    Einstein, A.

    2015-01-01

    laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser,

  17. Multidiagnostic analysis of ion dynamics in ultrafast laser ablation of metals over a large fluence range

    Energy Technology Data Exchange (ETDEWEB)

    Anoop, K. K., E-mail: anoop.kiliyanamkandy@unina.it; Bruzzese, R.; Amoruso, S. [CNR-SPIN and Dipartimento di Fisica, Universita degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, Napoli 80126 (Italy); Polek, M. P. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Harilal, S. S. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)

    2015-02-28

    The dynamics of ions in ultrafast laser ablation of metals is studied over fluences ranging from the ablation threshold up to ≈75 J/cm{sup 2} by means of three well-established diagnostic techniques. Langmuir probe, Faraday cup, and spectrally resolved intensified charge coupled device imaging simultaneously monitored the ions produced during ultrafast laser ablation of a pure copper target with 800 nm, ≈50 fs, Ti: Sapphire laser pulses. The fluence dependence of ion yield is analyzed, resulting in the observance of three different regimes. The specific ion yield shows a maximum at about 4–5 J/cm{sup 2}, followed by a gradual reduction and a transition to a high-fluence regime above ≈50 J/cm{sup 2}. The fluence dependence of the copper ions angular distribution is also analyzed, observing a gradual increase in forward-peaking of Cu ions for fluences up to ≈10 J/cm{sup 2}. A broader ion component is observed at larger angles for fluences larger than ≈10 J/cm{sup 2}. Finally, an experimental characterization of the ionic angular distribution for several metallic targets (Mg, Al, Cr, Fe, Cu, and W) is carried out at a relatively high fluence of ≈66 J/cm{sup 2}. Interestingly, the ion emission from the volatile metals shows a narrow, forward-peaked distribution, and a high peak ion yield compared to the refractory metals. Moreover, the width of ionic angular distributions presents a striking correlation with the peak ion yield.

  18. Contactless respiratory monitoring system for magnetic resonance imaging applications using a laser range sensor

    Directory of Open Access Journals (Sweden)

    Krug Johannes W.

    2016-09-01

    Full Text Available During a magnetic resonance imaging (MRI exam, a respiratory signal can be required for different purposes, e.g. for patient monitoring, motion compensation or for research studies such as in functional MRI. In addition, respiratory information can be used as a biofeedback for the patient in order to control breath holds or shallow breathing. To reduce patient preparation time or distortions of the MR imaging system, we propose the use of a contactless approach for gathering information about the respiratory activity. An experimental setup based on a commercially available laser range sensor was used to detect respiratory induced motion of the chest or abdomen. This setup was tested using a motion phantom and different human subjects in an MRI scanner. A nasal airflow sensor served as a reference. For both, the phantom as well as the different human subjects, the motion frequency was precisely measured. These results show that a low cost, contactless, laser-based approach can be used to obtain information about the respiratory motion during an MRI exam.

  19. First successful satellite laser ranging with a fibre-based transmitter

    CERN Document Server

    Hampf, Daniel; Wagner, Paul; Humbert, Leif; Hasenohr, Thomas; Riede, Wolfgang

    2016-01-01

    Satellite Laser Ranging (SLR) is an established technology used for geodesy, fundamental science and precise orbit determination. This paper reports on the first successful SLR measurement from the German Aerospace Center research observatory in Stuttgart. While many SLR stations are in operation, the experiment described here is unique in several ways: The modular system has been assembled completely from commercial off-the-shelf components, which increases flexibility and significantly reduces hardware costs. To our knowledge it has been the first time that an SLR measurement has been conducted using an optical fibre rather than a coud\\'e path to direct the light from the laser source onto the telescope. The transmitter operates at an output power of about 75 mW and a repetition rate of 3 kHz, and at a wavelength of 1064 nm. Due to its rather small diameter of only 80 {\\mu}{\\mu}m, the receiver detector features a low noise rate of less than 2 kHz and can be operated without gating in many cases. With this s...

  20. Novel Single-Frequency Diode Pumped Solid-State Lasers and Their Applications in Laser Ranging and Velocimetry

    Institute of Scientific and Technical Information of China (English)

    杨苏辉; 吴克瑛; 魏光辉

    2001-01-01

    Two models of laser diode pumped unidirectional single-frequency ring lasers with maximum single-frequency output powers of 1 W and 780mW are investigated. The statistical linewidth of the free-run laser is measured to be 2.1 kHz within 5μs by using a single-mode fibre link. We use the monolithic laser to measure the angular speed of a spinning motor and simulate a linearly frequency modulated continuous-wave ladar system in the laboratory.

  1. High-precision gravimetric survey in support of lunar laser ranging at Haleakala, Maui, 1976 - 1978

    Science.gov (United States)

    Schenck, B. E.; Laurila, S. H.

    1978-01-01

    The planning, observations and adjustment of high-precision gravity survey networks established on the islands of Maui and Oahu as part of the geodetic-geophysical program in support of lunar laser ranging at Haleakala, Maui, Hawaii are described. The gravity survey networks include 43 independently measured gravity differences along the gravity calibration line from Kahului Airport to the summit of Mt. Haleakala, together with some key points close to tidal gauges on Maui, and 40 gravity differences within metropolitan Honolulu. The results of the 1976-1978 survey are compared with surveys made in 1961 and in 1964-1965. All final gravity values are given in the system of the international gravity standardization net 1971 (IGSN 71); values are obtained by subtracting 14.57 mgal from the Potsdam value at the gravity base station at the Hickam Air Force Base, Honolulu.

  2. Testing for Lorentz violation: constraints on standard-model-extension parameters via lunar laser ranging.

    Science.gov (United States)

    Battat, James B R; Chandler, John F; Stubbs, Christopher W

    2007-12-14

    We present constraints on violations of Lorentz invariance based on archival lunar laser-ranging (LLR) data. LLR measures the Earth-Moon separation by timing the round-trip travel of light between the two bodies and is currently accurate to the equivalent of a few centimeters (parts in 10(11) of the total distance). By analyzing this LLR data under the standard-model extension (SME) framework, we derived six observational constraints on dimensionless SME parameters that describe potential Lorentz violation. We found no evidence for Lorentz violation at the 10(-6) to 10(-11) level in these parameters. This work constitutes the first LLR constraints on SME parameters.

  3. Exploring the depth range for three-dimensional laser machining with aberration correction.

    Science.gov (United States)

    Salter, P S; Baum, M; Alexeev, I; Schmidt, M; Booth, M J

    2014-07-28

    The spherical aberration generated when focusing from air into another medium limits the depth at which ultrafast laser machining can be accurately maintained. We investigate how the depth range may be extended using aberration correction via a liquid crystal spatial light modulator (SLM), in both single point and parallel multi-point fabrication in fused silica. At a moderate numerical aperture (NA = 0.5), high fidelity fabrication with a significant level of parallelisation is demonstrated at the working distance of the objective lens, corresponding to a depth in the glass of 2.4 mm. With a higher numerical aperture (NA = 0.75) objective lens, single point fabrication is demonstrated to a depth of 1 mm utilising the full NA, and deeper with reduced NA, while maintaining high repeatability. We present a complementary theoretical model that enables prediction of the effectiveness of SLM based correction for different aberration magnitudes.

  4. Test environments for the GRACE follow-on laser ranging interferometer

    Science.gov (United States)

    Görth, A.; Sanjuan, J.; Gohlke, M.; Rasch, S.; Abich, K.; Braxmaier, C.; Heinzel, G.

    2016-05-01

    In the year 2017 a follow-on mission to the very successful joint German/US mission GRACE (Gravity Recovery And Climate Experiment) will be launched. As of this day the two GRACE satellites have successfully been mapping the spatial and temporal varitations of the gravitational field of the Earth by satellite-to-satellite tracking for over a decade. The main science instrument on GRACE and its successor mission GRACE Follow-On which is used to measure the inter-satellite distance changes is a microwave link sensor. However, an additional instrument, the laser ranging interferometer (LRI), will be implemented into the architecture of the GRACE Follow-On satellites as a technology demonstrator. In this paper we will give a brief overview of a fiber-based test environment which is currently used during the assembly, integration and test of the LRI flight hardware.

  5. High-power laser delocalization in plasmas leading to long-range beam merging

    Energy Technology Data Exchange (ETDEWEB)

    Nakatsutsumi, M.; Marques, J.R.; Antici, P.; Bourgeois, N.; Romagnani, L.; Audebert, P.; Fuchs, J. [UPMC, CEA, CNRS, LULI, Ecole Polytech, F-91128 Palaiseau (France); Nakatsutsumi, M.; Kodama, R. [Osaka Univ, Grad Sch Engn, Suita, Osaka 5650871 (Japan); Antici, P. [Univ Roma La Sapienza, Dipartimento SBAI, I-00161 Rome (Italy); Feugeas, J.L.; Nicolai, P. [Univ Bordeaux 1, CNRS, CEA, Ctr Lasers Intenses and Applicat, F-33405 Talence (France); Lin, T. [Fox Chase Canc Ctr, Philadelphia, PA 19111 (United States)

    2010-07-01

    Attraction and fusion between co-propagating light beams, mutually coherent or not, can take place in nonlinear media as a result of the beam power modifying the refractive index of the medium. In the context of high-power light beams, induced modifications of the beam patterns could potentially impact many topics, including long-range laser propagation, the study of astrophysical colliding blast waves and inertial confinement fusion. Here, through experiments and simulations, we show that in a fully ionized plasma, which is a nonlinear medium, beam merging can take place for high-power and mutually incoherent beams that are initially separated by several beam diameters. This is in contrast to the usual assumption that this type of interaction is limited to beams separated by only one beam diameter. This effect, which is orders of magnitude more significant than Kerr-like nonlinearity in gases, demonstrates the importance of potential cross-talk amongst multiple beams in plasma. (authors)

  6. Lunar Laser-Ranging Detection of Light-Speed Anisotropy and Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-04-01

    Full Text Available The Apache Point Lunar Laser-ranging Operation (APOLLO, in NM, can detect pho- ton bounces from retroreflectors on the moon surface to 0.1ns timing resolution. This facility enables not only the detection of light speed anisotropy, which defines a local preferred frame of reference — only in that frame is the speed of light isotropic, but also fluctuations / turbulence (gravitational waves in the flow of the dynamical 3-space rela- tive to local systems / observers. So the APOLLO facility can act as an e ective “gravi- tational wave” detector. A recently published small data set from November 5, 2007, is analysed to characterise both the average anisotropy velocity and the wave / turbulence effects. The results are consistent with some 13 previous detections, with the last and most accurate being from the spacecraft earth-flyby Doppler-shift NASA data.

  7. Lunar Laser-Ranging Detection of Light-Speed Anisotropy and Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-04-01

    Full Text Available The Apache Point Lunar Laser-ranging Operation (APOLLO, in NM, can detect photon bounces from retroreflectors on the moon surface to 0.1ns timing resolution. This facility enables not only the detection of light speed anisotropy, which defines a local preferred frame of reference - only in that frame is the speed of light isotropic, but also fluctuations/turbulence (gravitational waves in the flow of the dynamical 3-space relative to local systems/observers. So the APOLLO facility can act as an effective "gravitational wave" detector. A recently published small data set from November 5, 2007, is analysed to characterise both the average anisotropy velocity and the wave/turbulence effects. The results are consistent with some 13 previous detections, with the last and most accurate being from the spacecraft earth-flyby Doppler-shift NASA data.

  8. Tunable Two-color Luminescence and Host–guest Energy Transfer of Fluorescent Chromophores Encapsulated in Metal-Organic Frameworks

    Science.gov (United States)

    Yan, Dongpeng; Tang, Yanqun; Lin, Heyang; Wang, Dan

    2014-01-01

    Co-assembly of chromophore guests with host matrices can afford materials which have photofunctionalities different from those of individual components. Compared with clay and zeolite materials, the use of metal–organic frameworks (MOFs) as a host structure for fabricating luminescent host–guest materials is still at an early stage. Herein, we report the incorporation of a laser dye, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), into stilbene-based and naphthalene-based MOF systems. The resulting materials exhibit blue/red two-color emission, and the intensity ratio of blue to red fluorescence varies in different planes within the MOF crystal as detected by 3D confocal fluorescence microscopy. The observed changes in ratiometric fluorescence suggest the occurrence of energy transfer from MOF host to DCM molecules, which can be further confirmed by periodic density functional theoretical (DFT) calculations. Moreover, selective changes in luminescence behavior are observed on treating the guest@MOF samples with volatile organic compounds (methanol, acetone and toluene), indicating that these host–guest systems have potential applications as fluorescence sensors. It can be expected that by rational selection of MOF hosts and guest chromophores with suitable emissive colors and energy levels, a wide variety of multi-color luminescent and energy-transfer systems can readily be prepared in a similar manner. PMID:24614015

  9. Ultrafast energy redistribution in C(60) fullerenes: a real time study by two-color femtosecond spectroscopy.

    Science.gov (United States)

    Shchatsinin, Ihar; Laarmann, Tim; Zhavoronkov, Nick; Schulz, Claus Peter; Hertel, Ingolf V

    2008-11-28

    Strong-field excitation and energy redistribution dynamics of C(60) fullerenes are studied by means of time-resolved mass spectrometry in a two-color femtosecond pump-probe setup. Resonant pre-excitation of the electronic system via the first dipole-allowed HOMO-->LUMO+1(t(1g)) (HOMO denotes highest occupied molecular orbital and LUMO denotes lowest unoccupied molecular orbital) transition with ultrashort 25 fs pulses at 399 nm of some 10(12) W cm(-2) results in a highly nonequilibrium distribution of excited electrons and vibrational modes in the neutral species. The subsequent coupling among the electronic and nuclear degrees of freedom is monitored by probing the system with time-delayed 27 fs pulses at 797 nm of some 10(13) W cm(-2). Direct information on the characteristic relaxation time is derived from the analysis of transient singly and multiply charged parent and fragment ion signals as a function of pump-probe delay and laser pulse intensity. The observed relaxation times tau(el) approximately 60-400 fs are attributed to different microcanonical ensembles prepared in the pre-excitation process and correspond to different total energy contents and energy sharing between electronic and vibrational degrees. The characteristic differences and trends allow one to extract a consistent picture for the formation dynamics of ions in different charge states and their fullerenelike fragments and give evidence to collective effects in multiple ionization such as plasmon-enhanced energy deposition.

  10. Selective ablation of WHHLMI rabbit atherosclerotic plaque by quantum cascade laser in the 5.7 μm wavelength range for less-invasive laser angioplasty

    Science.gov (United States)

    Hashimura, Keisuke; Ishii, Katsunori; Akikusa, Naota; Edamura, Tadataka; Yoshida, Harumasa; Awazu, Kunio

    2013-06-01

    We investigated the potential of a compact and high-power quantum cascade laser (QCL) in the 5.7 μm wavelength range for less-invasive laser angioplasty. Atherosclerotic plaques consist mainly of cholesteryl esters. Radiation at a wavelength of 5.75 μm is strongly absorbed in C=O stretching vibration mode of cholesteryl esters. Our previous study achieved to make cutting differences between a normal artery and an atherosclerotic lesions using nanosecond pulsed laser by difference-frequency generation (DFG laser) at the wavelength of 5.75 μm. For applying this technique to clinical treatment, a compact laser device is required. In this study, QCL irradiation effects to a porcine normal aorta were compared with DFG laser. Subsequently, QCL irradiation effects on an atherosclerotic aorta of myocardial infarction-prone Watanabe heritable hyperlipidemic rabbit (WHHLMI rabbit) and a normal rabbit aorta were observed. As a result, the QCL could make cutting differences between the rabbit atherosclerotic and normal aortas. On the other hand, the QCL induced more thermal damage to porcine normal aorta than the DFG laser at the irradiation condition of comparable ablation depths. In conclusion, the possibility of less-invasive and selective treatment of atherosclerotic plaques using the QCL in the 5.7 μm wavelength range was revealed, although improvement of QCL was required to prevent the thermal damage of a normal artery.

  11. Femtosecond laser nanostructuring of titanium metal towards fabrication of low-reflective surfaces over broad wavelength range

    Science.gov (United States)

    Dar, Mudasir H.; Kuladeep, R.; Saikiran, V.; Narayana Rao, D.

    2016-05-01

    We investigated experimentally the formation of laser induced periodic surface structures (LIPSS) on titanium (Ti) metal upon irradiation with linearly polarized Ti:Sapphire femtosecond (fs) laser pulses of ∼110 fs pulse width and 800 nm wavelength in air and water environments. It is observed that initially formed random and sparsely distributed nano-roughness (nanoholes, nanoparticles and nanoprotrusions) gets periodically structured with increase in number of laser pulses. In air at lower fluence, we observed the formation of high spatial frequency-LIPSS (HSFL) oriented parallel to the laser polarization direction, whereas at higher fluence formation of low spatial frequency-LIPSS (LSFL) were observed that are oriented perpendicular to the incident laser polarization. In water two types of subwavelength structures were observed, one with spatial periodicity of ∼λ/15 and oriented parallel to laser polarization, while the other oriented perpendicular to laser polarization with feature size of λ/4. The optimal conditions for fabricating periodic sub-wavelength structures are determined by controlling the fluence and pulse number. The fs laser induced surface modifications were found to suppress the specular reflection of the Ti surface over a wide wavelength range of 250-2000 nm to a great extent.

  12. Two-color QCD with non-zero chiral chemical potential

    Energy Technology Data Exchange (ETDEWEB)

    Braguta, V.V. [Institute for High Energy Physics NRC “Kurchatov Institute' ,142281 Protvino (Russian Federation); Far Eastern Federal University, School of Biomedicine,690950 Vladivostok (Russian Federation); Goy, V.A. [Far Eastern Federal University, School of Natural Sciences,690950 Vladivostok (Russian Federation); Ilgenfritz, E.M. [Joint Institute for Nuclear Research,BLTP, 141980 Dubna (Russian Federation); Kotov, A.Yu. [Institute of Theoretical and Experimental Physics,117259 Moscow (Russian Federation); Molochkov, A.V. [Far Eastern Federal University, School of Biomedicine,690950 Vladivostok (Russian Federation); Müller-Preussker, M.; Petersson, B. [Humboldt-Universität zu Berlin, Institut für Physik,12489 Berlin (Germany)

    2015-06-16

    The phase diagram of two-color QCD with non-zero chiral chemical potential is studied by means of lattice simulation. We focus on the influence of a chiral chemical potential on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulation is carried out with dynamical staggered fermions without rooting. The dependences of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented. The critical temperature is observed to increase with increasing chiral chemical potential.

  13. Flank transparency: transparent filters seen in dynamic two-color displays.

    Science.gov (United States)

    Wollschläger, D; Rodriguez, A M; Hoffman, D D

    2001-01-01

    Flank transparency is the perception of a colored transparent filter evoked by apparent-motion displays containing as few as two colors. Displays of flank transparency contain a random array of line segments placed on a uniform background. Small flanks are added to the line segments if the segments fall in the interior of a moving virtual shape, such as a virtual disk. This leads to the perception of a colored transparent disk with well-defined boundaries moving over the array of lines. Current qualitative and quantitative models of luminance and color conditions for perceptual transparency do not account for flank transparency as they require displays containing at least three different colors.

  14. Stokes image reconstruction for two-color microgrid polarization imaging systems.

    Science.gov (United States)

    Lemaster, Daniel A

    2011-07-18

    The Air Force Research Laboratory has developed a new microgrid polarization imaging system capable of simultaneously reconstructing linear Stokes parameter images in two colors on a single focal plane array. In this paper, an effective method for extracting Stokes images is presented for this type of camera system. It is also shown that correlations between the color bands can be exploited to significantly increase overall spatial resolution. Test data is used to show the advantages of this approach over bilinear interpolation. The bounds (in terms of available reconstruction bandwidth) on image resolution are also provided.

  15. An efficient flashlamp-pumped laser tunable in the IR range and using chromium-activated forsterite crystals

    Energy Technology Data Exchange (ETDEWEB)

    Baryshevskii, V.G.; Voloshin, V.A.; Demidovich, S.A.; Kimaev, A.E.; Korzhik, M.V. (Belorusskii Gosudarstvennyi Universitet, Minsk (Belorussian SSR))

    1990-11-01

    Efficient frequency-tunable lasing was obtained from Mg2SiO4:Cr single crystals under flashlamp pumping. The feasibility of using chromium ion absorption bands localized in the UV region for optical pumping is demonstrated. Wavelength tuning in the 1170-1330 nm range was obtained in a selective resonator for an output-mirror reflection coefficient of 86 percent. This laser may find application in fiber-optic communications and laser-radar systems.

  16. Demonstration of orbit determination for the Lunar Reconnaissance Orbiter using one-way laser ranging data

    Science.gov (United States)

    Bauer, S.; Hussmann, H.; Oberst, J.; Dirkx, D.; Mao, D.; Neumann, G. A.; Mazarico, E.; Torrence, M. H.; McGarry, J. F.; Smith, D. E.; Zuber, M. T.

    2016-09-01

    We used one-way laser ranging data from International Laser Ranging Service (ILRS) ground stations to NASA's Lunar Reconnaissance Orbiter (LRO) for a demonstration of orbit determination. In the one-way setup, the state of LRO and the parameters of the spacecraft and all involved ground station clocks must be estimated simultaneously. This setup introduces many correlated parameters that are resolved by using a priori constraints. Moreover the observation data coverage and errors accumulating from the dynamical and the clock modeling limit the maximum arc length. The objective of this paper is to investigate the effect of the arc length, the dynamical and modeling accuracy and the observation data coverage on the accuracy of the results. We analyzed multiple arcs using lengths of 2 and 7 days during a one-week period in Science Mission phase 02 (SM02, November 2010) and compared the trajectories, the post-fit measurement residuals and the estimated clock parameters. We further incorporated simultaneous passes from multiple stations within the observation data to investigate the expected improvement in positioning. The estimated trajectories were compared to the nominal LRO trajectory and the clock parameters (offset, rate and aging) to the results found in the literature. Arcs estimated with one-way ranging data had differences of 5-30 m compared to the nominal LRO trajectory. While the estimated LRO clock rates agreed closely with the a priori constraints, the aging parameters absorbed clock modeling errors with increasing clock arc length. Because of high correlations between the different ground station clocks and due to limited clock modeling accuracy, their differences only agreed at the order of magnitude with the literature. We found that the incorporation of simultaneous passes requires improved modeling in particular to enable the expected improvement in positioning. We found that gaps in the observation data coverage over 12 h (≈6 successive LRO orbits

  17. Full Waveform Analysis for Long-Range 3D Imaging Laser Radar

    Directory of Open Access Journals (Sweden)

    Wallace AndrewM

    2010-01-01

    Full Text Available The new generation of 3D imaging systems based on laser radar (ladar offers significant advantages in defense and security applications. In particular, it is possible to retrieve 3D shape information directly from the scene and separate a target from background or foreground clutter by extracting a narrow depth range from the field of view by range gating, either in the sensor or by postprocessing. We discuss and demonstrate the applicability of full-waveform ladar to produce multilayer 3D imagery, in which each pixel produces a complex temporal response that describes the scene structure. Such complexity caused by multiple and distributed reflection arises in many relevant scenarios, for example in viewing partially occluded targets, through semitransparent materials (e.g., windows and through distributed reflective media such as foliage. We demonstrate our methodology on 3D image data acquired by a scanning time-of-flight system, developed in our own laboratories, which uses the time-correlated single-photon counting technique.

  18. Lunar Laser Ranging Tests of the Equivalence Principle with the Earth and Moon

    CERN Document Server

    Williams, J G; Boggs, D H; Williams, James G.; Turyshev, Slava G.; Boggs, Dale H.

    2005-01-01

    A primary objective of the Lunar Laser Ranging (LLR) experiment is to provide precise observations of the lunar orbit that contribute to a wide range of science investigations. Time series of the highly accurate measurements of the distance between the Earth and Moon provide unique information used to determine whether, in accordance with the Equivalence Principle (EP), both of these celestial bodies are falling towards the Sun at the same rate, despite their different masses, compositions, and gravitational self-energies. Current LLR solutions give $(-1.0 \\pm 1.4) \\times 10^{-13}$ for any possible inequality in the ratios of the gravitational and inertial masses for the Earth and Moon, $\\Delta(M_G/M_I)$. This result, in combination with laboratory experiments on the weak equivalence principle, yields a strong equivalence principle (SEP) test of $\\Delta(M_G/M_I)_{\\tt SEP} = (-2.0 \\pm 2.0) \\times 10^{-13}$. Such an accurate result allows other tests of gravitational theories. The result of the SEP test transla...

  19. Long-range pulselength scaling of 351nm laser damage thresholds

    Science.gov (United States)

    Foltyn, S. R.; Jolin, L. J.

    1986-12-01

    In a series of experiments incorporating 351nm pulselength of 9, 26, 54, and 625ns, it was found that laser damage thresholds increased as (pulselength)/sup x/, and that the exponent averaged 0.36 and ranged, for different samples, from 0.23 to 0.48. Similar results were obtained when only catastrophic damage was considered. Samples included Al2O3/SiO2 in both AR and HR multilayers, HR's of Sc2O3/SiO2 and HfO2/SiO2, and Al-on-pyrex mirror; 9ns thresholds were between 0.2 to 5.6 J/sq cm. When these data were compared with a wide range of other results - for wavelengths from 0.25 to 10.6 microns and pulselengths down to 4ps - a remarkably consistent picture emerged. Damage thresholds, on average, increase approximately as the cube-root of pulselength from picoseconds to nearly a microsecond, and do so regardless of wavelength or material under test.

  20. Normal point generation and first photon bias correction in APOLLO lunar laser ranging

    Science.gov (United States)

    Michelsen, Eric Leonard

    2010-11-01

    The APOLLO Lunar Laser Ranging (LLR) system studies gravity by tracing out the orbit of the moon to ~1 mm, over many years. LLR in general provides extensive tests of many aspects of gravity, including deviations from General Relativity (GR), and time rate-of-change of the gravitational constant, G. APOLLO's precision is approximately 10x better than previous LLR measurements, enabling about an order of magnitude improvement in tests of gravity over the coming years. APOLLO requires complex data reduction methods to extract the distance so precisely. There are currently three choices for determining the round-trip-time to the moon from the data: the correlation method, the Augmented Calculation method, and the PDF-fit method. The results here suggest the PDF-fit method as preferable, for minimum random uncertainty over the full operating range of conditions, and stable systematic error below ~1 mm. As a second topic, the APOLLO system includes a systematic error called "First Photon Bias," which causes time measurements to be skewed early. An algorithm is presented and simulated, showing that it is inherently capable of achieving < 1 mm systematic error under normal operating conditions. However, the final algorithm requires a correction table calibrated from a more accurate model of shot-to-shot intensity fluctuations. Such a table could be the subject of future investigations.

  1. Determination of the tectonic plate motion by satellite laser ranging in 1999-2003

    Science.gov (United States)

    Schillak, S.; Wnuk, E.

    The paper presents results of the tectonic plates motion determination from satellite laser ranging in the period 1999-2003 The SLR station velocities were calculated from station geocentric coordinates determined from one month orbital arcs of Lageos-1 and Lageos-2 satellites for the first day of each arc The mean orbital RMS-of-fit for 5 years was equal to 15 mm The station velocities were determined for 29 stations and points in 1999-2003 it means for all SLR stations with data time span longer than 20 months The accuracy of station velocities determination varied from 0 4 mm year to 3 mm year dependent on quality of data and data span The difference of station velocities between ITRF2000 and the presented results were in the range 0-5 mm year Only for four stations Riyad Maidanak-2 Beijng and Arequipa after earthquake in 2001 the differences were statistically significant For the most stations is a good agreement with the NUVEL1A model of tectonic plates motion The significant differences were detected for stations Arequipa Concepcion Shanghai and Simosato The results differs from the model NUVEL1A in the station velocities and azimuths for South America tectonic plate and Japan

  2. Two-color HgCdTe infrared staring focal plane arrays

    Science.gov (United States)

    Smith, Edward P.; Pham, Le T.; Venzor, Gregory M.; Norton, Elyse; Newton, Michael; Goetz, Paul; Randall, Valerie; Pierce, Gregory; Patten, Elizabeth A.; Coussa, Raymond A.; Kosai, Ken; Radford, William A.; Edwards, John; Johnson, Scott M.; Baur, Stefan T.; Roth, John A.; Nosho, Brett; Jensen, John E.; Longshore, Randolph E.

    2003-12-01

    Raytheon Vision Systems (RVS) in collaboration with HRL Laboratories is contributing to the maturation and manufacturing readiness of third-generation two-color HgCdTe infrared staring focal plane arrays (FPAs). This paper will highlight data from the routine growth and fabrication of 256x256 30μm unit-cell staring FPAs that provide dual-color detection in the mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) spectral regions. FPAs configured for MWIR/MWIR, MWIR/LWIR and LWIR/LWIR detection are used for target identification, signature recognition and clutter rejection in a wide variety of space and ground-based applications. Optimized triple-layer-heterojunction (TLHJ) device designs and molecular beam epitaxy (MBE) growth using in-situ controls has contributed to individual bands in all two-color FPA configurations exhibiting high operability (>99%) and both performance and FPA functionality comparable to state-of-the-art single-color technology. The measured spectral cross talk from out-of-band radiation for either band is also typically less than 10%. An FPA architecture based on a single mesa, single indium bump, and sequential mode operation leverages current single-color processes in production while also providing compatibility with existing second-generation technologies.

  3. Geophysical interpretation of satellite laser ranging measurements of crustal movement in California

    Science.gov (United States)

    Cohen, Steven C.

    1985-12-01

    As determined by satellite laser ranging the rate of contraction of a 900 km baseline between sites located near Quincy in northern California and San Diego in southern California is about 61-65 mm/yr with a formal uncertainty of about 10 mm/yr (Christodoulidis et al., 1985). The measured changes in baseline length are a manifestation of the relative motion between the North America and Pacific tectonic plates. This long baseline result is compared to measurements made by more conventional means on shorter baselines. Additional information based on seismiscity, geology, and theoretical modelling is also analyzed. Deformation lying within a few tens of kilometers about the major faults in southern California accounts for most, but not all, of the observed motion. Further motion is attributable to a broader-scale deformation in southern California. Data suggesting crustal movements north of the Garlock fault, in and near the southern Sierra Nevada and local motion at an observatory are also critically reviewed. The best estimates of overall motion indicated by ground observations lie between 40 and 60 mm/yr. This lies within one or two standard deviations of that deduced from satellite ranging but the possibility of some unresolved deficit cannot be entirely dismissed. The long time scale RM2 plate tectonic model of Minster and Jordan (1978) predicts a contraction between 47 and 53 mm/yr depending on the extension rate of the Basin and Range. Thus the ground based observations, SLR results, and RM2 rates differ at about the 10 mm/yr level but are not inconsistent with one another within the data and model uncertainties.

  4. Optimization and control of the sweeping range in an Yb-doped self-sweeping fiber laser

    Science.gov (United States)

    Lobach, I. A.; Tkachenko, A. Yu; Kablukov, S. I.

    2016-04-01

    Influence of the laser cavity parameters (an active fiber length and output coupling losses) and the temperature of elements (active fiber and pump laser diode) on the sweeping range in an Yb-doped self-sweeping laser is investigated. The obtained results show that the sweeping spectral region is shifted to shorter wavelengths for shorter active fibers and with increasing absorbed power. This allows one to obtain self-sweeping operation in a broad range within a ytterbium gain bandwidth from 1028 to 1080 nm. At the same time, there are optimal cavity parameters at which the sweeping span is the broadest (>20 nm). Good agreement between the experimental sweeping range and the calculated maximum gain wavelength is demonstrated.

  5. ESA activities on satellite laser ranging to non-cooperative objects

    Science.gov (United States)

    Flohrer, Tim; Krag, Holger; Funke, Quirin; Jilete, Beatriz; Mancas, Alexandru

    2016-07-01

    Satellite laser ranging (SLR) to non-cooperative objects is an emerging technology that can contribute significantly to operational, modelling and mitigation needs set by the space debris population. ESA is conducting various research and development activities in SLR to non-cooperative objects. ESA's Space Situational Awareness (SSA) program supports specific activities in the Space Surveillance and Tracking (SST) segment. Research and development activities with operational aspects are run by ESA's Space Debris Office. At ESA SSA/SST comprises detecting, cataloguing and predicting the objects orbiting the Earth, and the derived applications. SST aims at facilitating research and development of sensor and data processing technologies and of related common components while staying complementary with, and in support of, national and multi-national European initiatives. SST promotes standardisation and interoperability of the technology developments. For SLR these goals are implemented through researching, developing, and deploying an expert centre. This centre shall coordinate the contribution of system-external loosely connected SLR sensors, and shall provide back calibration and expert evaluation support to the sensors. The Space Debris Office at ESA is responsible for all aspects related to space debris in the Agency. It is in charge of providing operational support to ESA and third party missions. Currently, the office studies the potential benefits of laser ranging to space debris objects to resolve close approaches to active satellites, to improve re-entry predictions of time and locations, and the more general SLR support during contingency situations. The office studies the determination of attitude and attitude motion of uncooperative objects with special focus on the combination of SLR, light-curve, and radar imaging data. Generating sufficiently precise information to allow for the acquisition of debris objects by a SLR sensor in a stare

  6. Study of efficiency and optimization parameters of laser device for measuring the range rate of a spacecraft

    Directory of Open Access Journals (Sweden)

    E. I. Starovoitov

    2014-01-01

    Full Text Available To replace the hand-held laser rangefinders on board transport spacecraft (SC a laser rangefinder-speedometer (LRS is developed and installed in the unpressurized area of SC to determine automatically the range rate. Crew, turning the active spacecraft by the video image that is formed by a docking camera, manually provides guidance of LRS to the passive SC. Using a generalized function of efficiency was estimated LRS characteristics. Comparison with the results of existing analogues shows that the LRS has the highest efficiency. As a result of relationship analysis of measuring speed and reliability accuracy of LRS laser source, Pareto sets are obtained, which enable providing the optimal operation conditions of a device It is found that the reliability function of LRS, which is equal to 0.999, is ensured at 1.0 s averaging time of range measurement and 0.8...0.9 m range measurement error. Increasing the averaging time of range measurement up to 1.5 s allows reliability function equal to 0.999 with the range measurement error of 2.5...2.5 m. Energy calculations are performed for 5 km range measurements on space complex with a complicated configuration such as the International Space Station (ISS for the maximum and minimum value of the effective reflection area. When the laser pulse energy is 11.5 mJ for measurements of diffusely reflected signal at ranges of 5 km at least a signal/noise ratio is no less than 10. With LRS illuminating the angular reflector, a measurement range is of over 30 km. Because of a large number of the angular reflectors on the ISS body is considered the use of the geometric factor to protect the photo-detector overload when receiving a signal from the nearby angular reflector. It is found that when the length of the base between the receiving and transmitting optical apertures is equal to 39 mm, a photo-detector is protected from the overload at the pulse energies up to 11.5 mJ. The results of efficiency evaluation

  7. A method to calculate zero-signature satellite laser ranging normal points for millimeter geodesy - a case study with Ajisai

    Science.gov (United States)

    Kucharski, Daniel; Kirchner, Georg; Otsubo, Toshimichi; Koidl, Franz

    2015-03-01

    High repetition-rate satellite laser ranging (SLR) offers new possibilities for the post-processing of the range measurements. We analyze 11 years of kHz SLR passes of the geodetic satellite Ajisai delivered by Graz SLR station (Austria) in order to improve the accuracy and precision of the principal SLR data product - normal points. The normal points are calculated by three different methods: 1) the range residuals accepted by the standard 2.5 sigma filter, 2) the range residuals accepted by the leading edge filter and 3) the range residuals given by the single corner cube reflector (CCR) panels of Ajisai.

  8. Evolution of the THz Beam Profile from a Two-Color Air Plasma Through a Beam Waist

    DEFF Research Database (Denmark)

    Strikwerda, Andrew; Pedersen, Pernille Klarskov; Jepsen, Peter Uhd

    2013-01-01

    We experimentally measure the profile of a THz beam generated by a two-color air plasma as it passes through a beam waist, and show that it can be approximated as a Bessel-Gauss beam.......We experimentally measure the profile of a THz beam generated by a two-color air plasma as it passes through a beam waist, and show that it can be approximated as a Bessel-Gauss beam....

  9. 3D indoor modeling using a hand-held embedded system with multiple laser range scanners

    Science.gov (United States)

    Hu, Shaoxing; Wang, Duhu; Xu, Shike

    2016-10-01

    Accurate three-dimensional perception is a key technology for many engineering applications, including mobile mapping, obstacle detection and virtual reality. In this article, we present a hand-held embedded system designed for constructing 3D representation of structured indoor environments. Different from traditional vehicle-borne mobile mapping methods, the system presented here is capable of efficiently acquiring 3D data while an operator carrying the device traverses through the site. It consists of a simultaneous localization and mapping(SLAM) module, a 3D attitude estimate module and a point cloud processing module. The SLAM is based on a scan matching approach using a modern LIDAR system, and the 3D attitude estimate is generated by a navigation filter using inertial sensors. The hardware comprises three 2D time-flight laser range finders and an inertial measurement unit(IMU). All the sensors are rigidly mounted on a body frame. The algorithms are developed on the frame of robot operating system(ROS). The 3D model is constructed using the point cloud library(PCL). Multiple datasets have shown robust performance of the presented system in indoor scenarios.

  10. Investigating relativity using lunar laser ranging - Geodetic precession and the Nordtvedt effect

    Science.gov (United States)

    Dickey, J. O.; Newhall, X. X.; Williams, J. G.

    1989-01-01

    The emplacement of retroreflectors on the moon by Apollo astronauts and the Russian Lunakhod spacecraft marked the inception of lunar laser ranging (LLR) and provided a natural laboratory for the study of general relativity. Continuing acquisition of increasingly accurate LLR data has provided enhanced sensitivity to general relativity parameters. Two relativistic effects are investigated in this paper: (1) the Nordtvedt effect, yielding a test of the strong equivalence principle, would appear as a distortion of the geocentric lunar orbit in the direction of the sun. The inclusion of recent LLR data limits the size of any such effect to 3 + or - 4 cm. The sensitivities to the various PPN quantities are also highlighted. (2) the geodetic precession of the lunar perigee is predicted by general relativity as a consequence of the motion of the earth-moon system about the sun; its theoretical magnitude is 19.2 mas/yr. Analysis presented here confirms this value and determines this quality to a 2 percent level.

  11. A total station spatial positioning method based on rotary laser scanning and ultrasonic ranging

    Science.gov (United States)

    Wu, Jun; Zhu, Jigui; Yu, Zhijing; Zhuge, Jingchang; Xue, Bin

    2016-11-01

    Total station spatial coordinator measuring technology is extensively applied in the large-scale measurement of industrial assembly and manufacturing for its flexibility and adaptability. The existing total station technology has some principal limits such as poor efficiency and single tasking; in order to achieve the total station spatial coordinator measuring technology with the advantages of multi-task, real-time measurement, and high accuracy, this paper presents a novel total station measurement method by using multi-laser plane constraints established through rotating planar planes and distance information obtained with an ultrasonic ranging method. With the spatial divergence angles of the optoelectronic scanning and ultrasonic arrays, this method can measure the spatial coordinates in multi-task and real-time with a single station and a portable target bar. Experimental results show that the proposed method is feasible and valid with satisfactory accuracy. The maximum distance measurement error is less than 0.2 mm in a volume that is 5 m far away from the station.

  12. False alarm suppression of multipulsed laser ranging system with Geiger-mode detector.

    Science.gov (United States)

    Luo, Hanjun; Xu, Huigang; Xu, Benlian; Ouyang, Zhengbiao; Fu, Yadan

    2015-06-10

    The false alarm probability is of great concern when designing and evaluating the performance of a multipulsed laser ranging system with a Geiger-mode avalanche photodiode. In this paper, based on the statistical distribution difference of the arrival time of the echo photons and noise in the time histogram, a false alarm suppression algorithm is presented. According to the data-processing method of the algorithm, the theoretical model of target detection and false alarm probability with a Poisson statistic and the system working at long dead time is established. With typical system design parameters, the target detection probability under different echo intensity and detection number is analyzed, and the influence of four main factors, namely, detection number, echo intensity, noise, and echo position, on the false alarm probability is investigated. The results show that multipulsed detection can improve the target detection probability, and using this developed algorithm, the false alarm probability can be effectively suppressed, to obtain an appropriate false alarm probability; it is suitable that the detection number is selected as 8; and stronger echo intensity, lower noise level, and a more frontal echo position can result in a lower false alarm probability.

  13. Indoor radiation mapping using the Laser Assisted Ranging and Data System (LARADS). Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-11-01

    The US Department of Energy`s (DOE`s) nuclear facilities require characterization and documentation of the results as part of planning and decision-making for decontamination and decommissioning (D and D) projects and to release areas that have been cleaned up. Conducting radiation surveys of indoor and outdoor surfaces and generating accurate survey reports is an important component of the D and D program. The Laser Assisted Ranging and Data System (LARADS) is a characterization technology that provides real-time data on the location and concentration levels of radiological contamination. The system can be utilized with a number of available detection instruments and can be integrated with existing data analysis and mapping software technologies to generate superior quality survey data reports. This innovative technology is competitive with baseline technologies in terms of cost and survey times, but is much more flexible and provides more useful reports. The system also has the capability of electronically logging survey data, making it easy to store and retrieve. Such data are scientifically derived and not subject to interpretation. The LARADS is an extremely attractive alternative to manually generated survey data reports.

  14. Dynamic Track Management in MHT for Pedestrian Tracking Using Laser Range Finder

    Directory of Open Access Journals (Sweden)

    Abdul Hadi Abd Rahman

    2015-01-01

    Full Text Available Real time pedestrian tracking could be one of the important features for autonomous navigation. Laser Range Finder (LRF produces accurate pedestrian data but a problem occurs when a pedestrian is represented by multiple clusters which affect the overall tracking process. Multiple Hypothesis Tracking (MHT is a proven method to solve tracking problem but suffers a large computational cost. In this paper, a multilevel clustering of LRF data is proposed to improve the accuracy of a tracking system by adding another clustering level after the feature extraction process. A Dynamic Track Management (DTM is introduced in MHT with multiple motion models to perform a track creation, association, and deletion. The experimental results from real time implementation prove that the proposed multiclustering is capable of producing a better performance with less computational complexity for a track management process. The proposed Dynamic Track Management is able to solve the tracking problem with lower computation time when dealing with occlusion, crossed track, and track deletion.

  15. Next generation retroreflector for lunar laser ranging: science, design and flight status

    Science.gov (United States)

    Currie, Douglas; Richards, Robert; Delle Monache, Giovanni

    2016-07-01

    The retroreflectors deployed during the Apollo Mission are still operating after 45 years. Analysis of the ranging data has resulted in the discovery and measurement of the liquid core of the moon about 15 years ago. This lunar laser ranging (LLR) program has also produced most of the best tests of Gravitation and General Relativity. However, over the years the ground stations have improved by a factor of ~200 so today the limit in ranging accuracy is due to the combination of the libration of the moon and the design of the Cube Corner Reflector (CCR) arrays. To address this, the University of Maryland, College Park (UMCP) and the INFN-LNF are developing the Next Generation Retroreflectors (NGR. Recently the UMCP and the LNF have signed an agreement with Moon Express, Inc., a commercial company pursuing the Google Lunar X Prize and a space transport business, to deploy four NGRs on the lunar surface, the first of which is expected to fly in the second quarter of 2017. A brief discussion will address the expected improvements in the understanding of Gravitational and General Relativity and the impact this may have on the multiple theories that have been proposed to explain Dark Matter and Dark Energy. The basic objectives, requirements and design will be reviewed. In particular, in order to maintain a signal level similar to that of Apollo 15, thermal gradients within the CCR must be maintain to less than 0.2oK. Since during lunar morning the CCR is at about 70oK and the housing is more than 300oK, the thermal design is critical. The structure and results of the required simulation programs will be reviewed. Finally, the current design of the entire package will be addressed. Looking toward the future, two areas look particularly interesting in extending the coverage of the theories of Gravitation, General Relativity, Dark Matter and Dark Energy. They will support even greater ranging accuracy, additional ground stations and increased coverage. The first is to

  16. Calibration between a Laser Range Scanner and an Industrial Robot Manipulator

    DEFF Research Database (Denmark)

    Andersen, Thomas Timm; Andersen, Nils Axel; Ravn, Ole

    2014-01-01

    In this paper we present a method for findingthe transformation between a laser scanner and a robotmanipulator. We present the design of a flat calibration targetthat can easily fit between a laser scanner and a conveyor belt,making the method easily implementable in a manufacturingline.We prove...

  17. Processing and Application of ICESat Large Footprint Full Waveform Laser Range Data

    NARCIS (Netherlands)

    Duong, V.H.

    2010-01-01

    In the last two decades, laser scanning systems made the transition from scientific research to the commercial market. Laser scanning has a large variety of applications such as digital elevation models, forest inventory and man-made object reconstruction, and became the most required input data for

  18. Long-range laser scanning and 3D imaging for the Gneiss quarries survey

    Science.gov (United States)

    Schenker, Filippo Luca; Spataro, Alessio; Pozzoni, Maurizio; Ambrosi, Christian; Cannata, Massimiliano; Günther, Felix; Corboud, Federico

    2016-04-01

    In Canton Ticino (Southern Switzerland), the exploitation of natural stone, mostly gneisses, is an important activity of valley's economies. Nowadays, these economic activities are menaced by (i) the exploitation costs related to geological phenomena such as fractures, faults and heterogeneous rocks that hinder the processing of the stone product, (ii) continuously changing demand because of the evolving natural stone fashion and (iii) increasing administrative limits and rules acting to protect the environment. Therefore, the sustainable development of the sector for the next decades needs new and effective strategies to regulate and plan the quarries. A fundamental step in this process is the building of a 3D geological model of the quarries to constrain the volume of commercial natural stone and the volume of waste. In this context, we conducted Terrestrial Laser Scanning surveys of the quarries in the Maggia Valley to obtain a detailed 3D topography onto which the geological units were mapped. The topographic 3D model was obtained with a long-range laser scanning Riegl VZ4000 that can measure from up to 4 km of distance with a speed of 147,000 points per second. It operates with the new V-line technology, which defines the surface relief by sensing differentiated signals (echoes), even in the presence of obstacles such as vegetation. Depending on the esthetics of the gneisses, we defined seven types of natural stones that, together with faults and joints, were mapped onto the 3D models of the exploitation sites. According to the orientation of the geological limits and structures, we projected the different rock units and fractures into the excavation front. This way, we obtained a 3D geological model from which we can quantitatively estimate the volume of the seven different natural stones (with different commercial value) and waste (with low commercial value). To verify the 3D geological models and to quantify exploited rock and waste volumes the same

  19. Multiscale Monte Carlo equilibration: Two-color QCD with two fermion flavors

    CERN Document Server

    Detmold, William

    2016-01-01

    We demonstrate the applicability of a recently proposed multi-scale thermalization algorithm to two-color quantum chromodynamics (QCD) with two mass-degenerate fermion flavors. The algorithm involves refining an ensemble of gauge configurations that had been generated using a renormalization group (RG) matched coarse action, thereby producing a fine ensemble that is close to the thermalized distribution of a target fine action; the refined ensemble is subsequently rethermalized using conventional algorithms. Although the generalization of this algorithm from pure Yang-Mills theory to QCD with dynamical fermions is straight-forward, we find that in the latter case, the method is susceptible to numerical instabilities during the initial stages of rethermalization when using the hybrid Monte Carlo algorithm. We find that these instabilities arise from large fermion forces in the evolution, which are attributed to an accumulation of spurious near-zero modes of the Dirac operator. We propose a simple strategy for ...

  20. Statistical analysis of efficient unbalanced factorial designs for two-color microarray experiments.

    Science.gov (United States)

    Tempelman, Robert J

    2008-01-01

    Experimental designs that efficiently embed a fixed effects treatment structure within a random effects design structure typically require a mixed-model approach to data analyses. Although mixed model software tailored for the analysis of two-color microarray data is increasingly available, much of this software is generally not capable of correctly analyzing the elaborate incomplete block designs that are being increasingly proposed and used for factorial treatment structures. That is, optimized designs are generally unbalanced as it pertains to various treatment comparisons, with different specifications of experimental variability often required for different treatment factors. This paper uses a publicly available microarray dataset, as based upon an efficient experimental design, to demonstrate a proper mixed model analysis of a typical unbalanced factorial design characterized by incomplete blocks and hierarchical levels of variability.

  1. Fabrication of optical multilayer for two-color phase plate in super-resolution microscope.

    Science.gov (United States)

    Iketaki, Yoshinori; Kitagawa, Katsuichi; Hidaka, Kohjiro; Kato, Naoki; Hirabayashi, Akira; Bokor, Nandor

    2014-07-01

    In super-resolution microscopy based on fluorescence depletion, the two-color phase plate (TPP) is an indispensable optical element, which can independently control the phase shifts for two beams of different color, i.e., the pump and erase beams. By controlling a phase shift of the erase beam through the TPP, the erase beam can be modulated into a doughnut shape, while the pump beam maintains the initial Gaussian shape. To obtain a reliable optical multiplayer (ML) for the TPP, we designed a ML with only two optical layers by performing numerical optimization. The measured phase shifts generated by the fabricated ML using interferometry correspond to the design values. The beam profiles in the focal plane are also consistent with theoretical results. Although the fabricated ML consists of only two optical layers, the ML can provide a suitable phase modulation function for the TPP in a practical super-resolution microscope.

  2. Magnetic catalysis (and inverse catalysis) at finite temperature in two-color lattice QCD

    CERN Document Server

    Ilgenfritz, E -M; Petersson, B; Schreiber, A

    2013-01-01

    Two-color lattice QCD with N_f=4 staggered fermion degrees of freedom (no rooting trick is applied) with equal electric charge q is studied in a homogeneous magnetic background field B and at non-zero temperature T. In order to circumvent renormalization as a function of the bare coupling we apply a fixed-scale approach. We study the influence of the magnetic field on the critical temperature. At rather small pseudo-scalar meson mass (m_pi \\approx 175 MeV \\approx T_c(B=0)) we confirm magnetic catalysis for sufficiently strong magnetic field strength, while at T=195 MeV and weak magnetic field (qB {\\lesssim} 0.8 GeV^2) we find a rise of the Polyakov loop with qB and thus, indications for an inverse magnetic catalysis.

  3. Calibration of a two-color soft x-ray diagnostic for electron temperature measurement

    Energy Technology Data Exchange (ETDEWEB)

    Reusch, L. M., E-mail: lmmcguire@wisc.edu; Den Hartog, D. J.; Goetz, J.; McGarry, M. B. [University of Wisconsin - Madison, Madison, Wisconsin 53703 (United States); Franz, P. [Consorzio RFX, Padova (Italy); Stephens, H. D. [University of Wisconsin - Madison, Madison, Wisconsin 53703 (United States); Pierce College Fort Steilacoom, Lakewood, Washington 98498 (United States)

    2016-11-15

    The two-color soft x-ray (SXR) tomography diagnostic on the Madison Symmetric Torus is capable of making electron temperature measurements via the double-filter technique; however, there has been a 15% systematic discrepancy between the SXR double-filter (SXR{sub DF}) temperature and Thomson scattering (TS) temperature. Here we discuss calibration of the Be filters used in the SXR{sub DF} measurement using empirical measurements of the transmission function versus energy at the BESSY II electron storage ring, electron microprobe analysis of filter contaminants, and measurement of the effective density. The calibration does not account for the TS and SXR{sub DF} discrepancy, and evidence from experiments indicates that this discrepancy is due to physics missing from the SXR{sub DF} analysis rather than instrumentation effects.

  4. Biosynthetic labeling and two-color imaging of phospholipids in cells.

    Science.gov (United States)

    Jao, Cindy Y; Roth, Mary; Welti, Ruth; Salic, Adrian

    2015-02-09

    Phospholipids with a choline head group are abundant components of all biological membranes, performing critical functions in cellular structure, metabolism, and signaling. In spite of their importance, our ability to visualize choline phospholipids in vivo remains very limited. We present a simple and robust chemical strategy to image choline phospholipids, based on the metabolic incorporation of azidocholine analogues, that accurately reflects the normal biosynthetic incorporation of choline into cellular phospholipids. Azidocholine-labeled phospholipids can be imaged in cells with high sensitivity and resolution, following derivatization with fluorophores, by bio-orthogonal chemical reactions compatible with live-cell imaging. We used this method to visualize the subcellular localization of choline phospholipids. We also demonstrate that double metabolic labeling with azidocholine and propargylcholine allows sensitive two-color imaging of choline phospholipids. Our method represents a powerful approach to directly image phospholipids, and to study their dynamics in cells and tissues.

  5. Calibration of a two-color soft x-ray diagnostic for electron temperature measurement

    Science.gov (United States)

    Reusch, L. M.; Den Hartog, D. J.; Franz, P.; Goetz, J.; McGarry, M. B.; Stephens, H. D.

    2016-11-01

    The two-color soft x-ray (SXR) tomography diagnostic on the Madison Symmetric Torus is capable of making electron temperature measurements via the double-filter technique; however, there has been a 15% systematic discrepancy between the SXR double-filter (SXRDF) temperature and Thomson scattering (TS) temperature. Here we discuss calibration of the Be filters used in the SXRDF measurement using empirical measurements of the transmission function versus energy at the BESSY II electron storage ring, electron microprobe analysis of filter contaminants, and measurement of the effective density. The calibration does not account for the TS and SXRDF discrepancy, and evidence from experiments indicates that this discrepancy is due to physics missing from the SXRDF analysis rather than instrumentation effects.

  6. Two-color in vivo imaging of photoreceptor apoptosis and development in Drosophila.

    Science.gov (United States)

    Gambis, Alexis; Dourlen, Pierre; Steller, Hermann; Mollereau, Bertrand

    2011-03-01

    We report a new two-color fluorescent imaging system to visualize the mosaic adult photoreceptor neurons (PRs) in real-time. Using this method, we examined a collection of 434 mutants and identified genes required for PR survival, planar cell polarity (PCP), patterning and differentiation. We could track the progression of PR degeneration in living flies. By introducing the expression of p35, a caspase inhibitor, we found mutations that specifically activate caspase-dependent death. Moreover, we showed that grh is required in R3 for correct PCP establishment. The "Tomato/GFP-FLP/FRT" method allows high-throughput, rapid and precise identification of survival and developmental pathways in living adult PRs at single-cell resolution.

  7. Fabrication of two-color annular hybrid wave plate for three-dimensional super-resolution microscopy

    Science.gov (United States)

    Kumagai, Hiroshi; Iketaki, Yoshinori; Jahn, Kornel; Bokor, Nador

    2016-03-01

    In super-resolution microscopy, we use fluorescence depletion, where an erase beam quenches a molecule in the S1 state generated by a pump beam, and then prevents fluorescence from the S1 state. When a tight doughnut shaped erase beam with is focused on the dyed sample together with a Gaussian pump beam, the remaining fluorescence spot in the focal plane becomes smaller than the diffraction-limited size. Applying destructive interference to the erase beam, erase beam has a minute three-dimensional dark spot surrounded by the light near the focal region. Since this spot introduces fluorescence depletion along the optical axis as in the focal plane, we can achieve three-dimensional super-resolution microscopy. However, to overcome the diffraction limit, an extremely precise optical alignment is required for projecting the focused pump beam into the dark spot of the erase beam. To resolve this technical issue, we fabricated a two-color annular hybrid wave plate (TAHWP) by combining two multi-order wave quartz plates. Although the pump and erase beams co-axially pass through the plate; the pump beam retains its original Gaussian shape, while the erase beam undergoes destructive interference. Inserting the TAHWP into a commercial scanning laser microscope, a three-dimensional spherical fluorescence spot with a volume of (~100 nm)3 can be created. Beside eliminating alignment problems and yielding a compact setup, the TAHWP makes our proposed method very suitable for commercial microscope systems. In this study, we report about detailed fabrication procedure and three-dimensional image properties given by the TAHWP.

  8. A folded-sandwich polarization-entangled two-color photon pair source with large tuning capability for applications in hybrid quantum architectures

    CERN Document Server

    Dietz, Otto; Kreißl, Thomas; Herzog, Ulrike; Kroh, Tim; Ahlrichs, Andreas; Benson, Oliver

    2015-01-01

    We demonstrate a two-color entangled pho ton pair source which can be adapted easily to a wide range of wavelengths combinations. A Fresnel rhomb as a geometrical quarter-wave plate and a versatile combination of compensation crystals are key components of the source. Entanglement of two photons at the Cs D1 line (894.3 nm) and at the telecom O-band (1313.1 nm) with a fidelity of $F = 0.753 \\pm 0.021$ is demonstrated and improvements of the setup are discussed.

  9. Selective treatment of carious dentin using a mid-infrared tunable pulsed laser at 6 μm wavelength range

    Science.gov (United States)

    Saiki, Masayuki; Ishii, Katsunori; Yoshikawa, Kazushi; Yasuo, Kenzo; Yamamoto, Kazuyo; Awazu, Kunio

    2011-03-01

    Optical technologies have good potential for caries detection, prevention, excavation, and the realization of minimal intervention dentistry. This study aimed to develop a selective excavation technique of carious tissue using the specific absorption in 6 μm wavelength range. Bovine dentin demineralized with lactic acid solution was used as a carious dentin model. A mid-infrared tunable pulsed laser was obtained by difference-frequency generation technique. The wavelength was tuned to 6.02 and 6.42 μm which correspond to absorption bands called amide I and amide II, respectively. The laser delivers 5 ns pulse width at a repetition rate of 10 Hz. The morphological change after irradiation was observed with a scanning electron microscope, and the measurement of ablation depth was performed with a confocal laser microscope. At λ = 6.02 μm and the average power density of 15 W/cm2, demineralized dentin was removed selectively with less-invasive effect on sound dentin. The wavelength of 6.42 μm also showed the possibility of selective removal. High ablation efficiency and low thermal side effect were observed using the nanosecond pulsed laser with λ = 6.02 μm. In the near future, development of compact laser device will open the minimal invasive laser treatment to the dental clinic.

  10. Diode lasers with asymmetric barriers for 850 nm spectral range: experimental studies of power characteristics

    OpenAIRE

    Zubov, F. I.; Zhukov, A. E.; Shernyakov, Yu. M.; M. V. Maximov; Semenova, Elizaveta; Asryan, L. V.

    2015-01-01

    It is demonstrated that the use of asymmetric barrier layers in a waveguide of a diode laser suppress non-linearity of light-current characteristic and thus improve its power characteristics under high current injection. The results are presented for 850-nm AlGaAs/GaAs broad-area lasers with GaInP and AlInGaAs asymmetric barriers.

  11. A grating-coupled external cavity InAs/InP quantum dot laser with 85-nm tuning range

    Science.gov (United States)

    Wei, Heng; Jin, Peng; Luo, Shuai; Ji, Hai-Ming; Yang, Tao; Li, Xin-Kun; Wu, Jian; An, Qi; Wu, Yan-Hua; Chen, Hong-Mei; Wang, Fei-Fei; Wu, Ju; Wang, Zhan-Guo

    2013-09-01

    The optical performance of a grating-coupled external cavity laser based on InAs/InP quantum dots is investigated. Continuous tuning from 1391 nm to 1468 nm is realized at an injection current of 1900 mA. With the injection current increasing to 2300 mA, the tuning is blue shifted to some extent to the range from 1383 nm to 1461 nm. By combining the effect of the injection current with the grating tuning, the total tuning bandwidth of the external cavity quantum-dot laser can reach up to 85 nm. The dependence of the threshold current on the tuning wavelength is also presented.

  12. MoonLIGHT: A USA-Italy lunar laser ranging retroreflector array for the 21st century

    Science.gov (United States)

    Martini, M.; Dell'Agnello, S.; Currie, D.; Delle Monache, G.; Vittori, R.; Chandler, J. F.; Cantone, C.; Boni, A.; Berardi, S.; Patrizi, G.; Maiello, M.; Garattini, M.; Lops, C.; March, R.; Bellettini, G.; Tauraso, R.; Intaglietta, N.; Tibuzzi, M.; Murphy, T. W.; Bianco, G.; Ciocci, E.

    2012-12-01

    Since the 1970s Lunar Laser Ranging (LLR) to the Apollo Cube Corner Retroreflector (CCR) arrays (developed by the University of Maryland, UMD) have supplied significant tests of General Relativity: possible changes in the gravitational constant, gravitational self-energy, weak equivalence principle, geodetic precession, inverse-square force-law. LLR has also provided significant information on the composition and origin of the Moon. This is the only Apollo experiment still in operation. In the 1970s Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo CCR arrays dominate the error budget. With the project MoonLIGHT (Moon Laser Instrumentation for General relativity High-accuracy Tests), in 2006 INFN-LNF joined UMD in the development and test of a new-generation LLR payload made by a single, large CCR (100 mm diameter) unaffected by librations. In particular, INFN-LNF built and is operating a new experimental apparatus (Satellite/lunar laser ranging Characterization Facility, SCF) and created a new industry-standard test procedure (SCF-Test) to characterize and model the detailed thermal behavior and the optical performance of CCRs in laboratory-simulated space conditions, for industrial and scientific applications. Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP) and the temperature distribution of retroreflector payloads under thermal conditions produced with a solar simulator. The apparatus includes infrared cameras for non-invasive thermometry, thermal control and real-time payload movement to simulate satellite orientation on orbit with respect to solar illumination and laser interrogation beams. These capabilities provide: unique pre-launch performance validation of the space segment of LLR/SLR (Satellite Laser

  13. 750 nm 1.5 W frequency-doubled semiconductor disk laser with a 44 nm tuning range.

    Science.gov (United States)

    Saarinen, Esa J; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G

    2015-10-01

    We demonstrate 1.5 W of output power at the wavelength of 750 nm by intracavity frequency doubling a wafer-fused semiconductor disk laser diode-pumped at 980 nm. An optical-to-optical efficiency of 8.3% was achieved using a bismuth borate crystal. The wavelength of the doubled emission could be tuned from 720 to 764 nm with an intracavity birefringent plate. The beam quality parameter M2 of the laser output was measured to be below 1.5 at all pump powers. The laser is a promising tool for biomedical applications that can take advantage of the large penetration depth of light in tissue in the 700-800 nm spectral range.

  14. Extended femtosecond laser wavelength range to 330 nm in a high power LBO based optical parametric oscillator.

    Science.gov (United States)

    Fan, Jintao; Gu, Chenglin; Wang, Chingyue; Hu, Minglie

    2016-06-13

    We experimentally demonstrate a compact tunable, high average power femtosecond laser source in the ultraviolet (UV) regime. The laser source is based on intra-cavity frequency doubling of a temperature-tuned lithium tribotate (LBO) optical parametric oscillator (OPO), synchronously pumped at 520 nm by a frequency-doubled, Yb-fiber femtosecond laser amplifier system. By adjusting crystal temperature, the OPO can provide tunable visible to near-infrared (NIR) signal pulse, which have a wide spectral tuning range from 660 to 884 nm. Using a β-barium borate (BBO) crystal for intra-cavity frequency doubling, tunable femtosecond UV pulse are generated across 330~442 nm with up to 364 mW at 402 nm.

  15. Megahertz FDML Laser with up to 143nm Sweep Range for Ultrahigh Resolution OCT at 1050nm

    CERN Document Server

    Kolb, Jan Philip; Eibl, Mattias; Pfeiffer, Tom; Wieser, Wolfgang; Huber, Robert

    2016-01-01

    We present a new design of a Fourier Domain Mode Locked laser (FDML laser), which provides a new record in sweep range at ~1um center wavelength: At the fundamental sweep rate of 2x417 kHz we reach 143nm bandwidth and 120nm with 4x buffering at 1.67MHz sweep rate. The latter configuration of our system is characterized: The FWHM of the point spread function (PSF) of a mirror is 5.6um (in tissue). Human in vivo retinal imaging is performed with the MHz laser showing more details in vascular structures. Here we could measure an axial resolution of 6.0um by determining the FWHM of specular reflex in the image. Additionally, challenges related to such a high sweep bandwidth such as water absorption are investigated.

  16. Megahertz FDML laser with up to 143nm sweep range for ultrahigh resolution OCT at 1050nm

    Science.gov (United States)

    Kolb, Jan Philip; Klein, Thomas; Eibl, Matthias; Pfeiffer, Tom; Wieser, Wolfgang; Huber, Robert

    2016-03-01

    We present a new design of a Fourier Domain Mode Locked laser (FDML laser), which provides a new record in sweep range at ~1μm center wavelength: At the fundamental sweep rate of 2x417 kHz we reach 143nm bandwidth and 120nm with 4x buffering at 1.67MHz sweep rate. The latter configuration of our system is characterized: The FWHM of the point spread function (PSF) of a mirror is 5.6μm (in tissue). Human in vivo retinal imaging is performed with the MHz laser showing more details in vascular structures. Here we could measure an axial resolution of 6.0μm by determining the FWHM of specular reflex in the image. Additionally, challenges related to such a high sweep bandwidth such as water absorption are investigated.

  17. Investigation on the Ability of Antireflection Coating to Withstand the Destructive Effects of Laser Radiation in IR Range (10.6 Micrometers),

    Science.gov (United States)

    2014-09-26

    at the mid-IR, KCl and NaCl are commonly selected as substrates. But for the CO2 laser , a Ge substrate coated with a *i ZnS AR coating, is still widely...intensity of the laser increases, these microscopic damages interact with the laser , thus absorbing more energy from the light field, and the...FOREIGN TECHNOLOGY DIVISION INVESTIGATION ON THE ABILITY OF ANTIREFLECTION COATING TO WITHSTAND THE DESTRUCTIVE EFFECTS OF LASER RADIATION IN IR RANGE

  18. Optimized design of a TOF laser range finder based on time-correlated single-photon counting

    Science.gov (United States)

    Wang, Huanqin; Yang, Yixin; Huang, Zhe; Cao, YangYang; Gui, Huaqiao

    2014-11-01

    A time-of-flight (TOF) laser range finder based on time-correlated single photon counting (TCSPC) has been developed. By using a Geiger-mode avalanche photodiode (G-APD) with the ability of detecting single-photon events and Time-to-Digital Converter (TDC) with picosecond resolution, a good linearity with 4.5 cm range precision can be achieved in the range of 1-10 m. This paper highlights a significant advance in improving the key parameters of this system, including the range precision and measurement dynamic range. In our experiments, it was found that both of the precision and the measurement dynamic range were limited by the signal to noise rate (SNR) and the inherent jitter of system. The range precision can be improved by enhancing the SNR of system. However, when the SNR is high enough, the main factors affecting the range precision will turn into the inherent jitter, which makes the range precision can not be improved infinitely. Moreover, the inherent jitter generated by pulsed laser and the signal processing module has been measured, and its influence on the system performance has also been discussed. Taking all of these factors into account, some optimized designs have been proposed to improve range precision and dynamic range simultaneously. The final experiment results show that, after all of these optimization designs, the range precision of system is better than 1.2 cm and the measurement dynamic range is enlarged to 54 m when the sampling time is as short as 1 ms, which is sufficient for many applications of 3D object recognition, computer vision, reverse engineering and virtual reality.

  19. Theory, design, and performance of extended tuning range semiconductor lasers with sampled gratings

    Energy Technology Data Exchange (ETDEWEB)

    Jayaraman, V.; Chuang, Zuon-Min; Coldren, L.A. (Univ. of California, Santa Barbara, CA (United States))

    1993-06-01

    The authors have recently demonstrated 57 nm of tuning in a monolithic semiconductor laser using conventional DBR technology with grating elements removed in a periodic fashion. This paper describes the theory and design of these sampled grating tunable lasers. They first calculate sampled grating reflectivity. They then present normalized design curves which quantify tradeoffs involved in a sampled grating DBR laser with two mismatched sampled grating mirrors. These results are applied to design example in the InP-InGaAsP system. The design example provides 70 nm tuning wile maintaining [gt]30 dB MSR, with fractional index change [Delta][mu]/[mu] [lt] 0.2% in the mirrors, and only 1 mm of total sampled grating length. Section 4 summarizes recent experimental results, and compares them to theory. They also analyze other device structures which make use of sampled gratings.

  20. Enhanced sensitivity in H photofragment detection by two-color reduced-Doppler ion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Epshtein, Michael; Portnov, Alexander; Kupfer, Rotem; Rosenwaks, Salman; Bar, Ilana, E-mail: ibar@bgu.ac.il [Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2013-11-14

    Two-color reduced-Doppler (TCRD) and one-color velocity map imaging (VMI) were used for probing H atom photofragments resulting from the ∼243.1 nm photodissociation of pyrrole. The velocity components of the H photofragments were probed by employing two counterpropagating beams at close and fixed wavelengths of 243.15 and 243.12 nm in TCRD and a single beam at ∼243.1 nm, scanned across the Doppler profile in VMI. The TCRD imaging enabled probing of the entire velocity distribution in a single pulse, resulting in enhanced ionization efficiency, as well as improved sensitivity and signal-to-noise ratio. These advantages were utilized for studying the pyrrole photodissociation at ∼243.1 and 225 nm, where the latter wavelength provided only a slight increase in the H yield over the self-signal from the probe beams. The TCRD imaging enabled obtaining high quality H{sup +} images, even for the low H photofragment yields formed in the 225 nm photolysis process, and allowed determining the velocity distributions and anisotropy parameters and getting insight into pyrrole photodissociation.

  1. Phase diagram of dense two-color QCD within lattice simulations

    Science.gov (United States)

    Braguta, V. V.; Ilgenfritz, E.-M.; Kotov, A. Yu.; Molochkov, A. V.; Nikolaev, A. A.

    2017-03-01

    We present the results of a low-temperature scan of the phase diagram of dense two-color QCD with Nf = 2 quarks. The study is conducted using lattice simulation with rooted staggered quarks. At small chemical potential we observe the hadronic phase, where the theory is in a confining state, chiral symmetry is broken, the baryon density is zero and there is no diquark condensate. At the critical point μ = mπ/2 we observe the expected second order transition to Bose-Einstein condensation of scalar diquarks. In this phase the system is still in confinement in conjunction with nonzero baryon density, but the chiral symmetry is restored in the chiral limit. We have also found that in the first two phases the system is well described by chiral perturbation theory. For larger values of the chemical potential the system turns into another phase, where the relevant degrees of freedom are fermions residing inside the Fermi sphere, and the diquark condensation takes place on the Fermi surface. In this phase the system is still in confinement, chiral symmetry is restored and the system is very similar to the quarkyonic state predicted by SU(Nc) theory at large Nc.

  2. Two-color detector: Mercury-cadmium-telluride as a terahertz and infrared detector

    Energy Technology Data Exchange (ETDEWEB)

    Sizov, F.; Zabudsky, V.; Petryakov, V.; Golenkov, A.; Andreyeva, K.; Tsybrii, Z. [Institute of Semiconductor Physics, 03028 Kiev (Ukraine); Dvoretskii, S. [Institute of Semiconductor Physics of SB RAS, 630090 Novosibirsk (Russian Federation)

    2015-02-23

    In this paper, issues associated with the development of infrared (IR) and terahertz (THz) radiation detectors based on HgCdTe are discussed. Two-color un-cooled and cooled to 78 K narrow-gap mercury-cadmium-telluride semiconductor thin layers with antennas were considered both as sub-THz (sub-THz) direct detection bolometers and 3–10 μm IR photoconductors. The noise equivalent power (NEP) for one of the detectors studied at ν ≈ 140 GHz reaches NEP{sub 300 K} ≈ 4.5 × 10{sup −10} W/Hz{sup 1/2} and NEP{sub 78 K} ≈ 5 × 10{sup −9} W/Hz{sup 1/2}. The same detector used as an IR photoconductor showed the responsivity at temperatures T = 78 K and 300 K with signal-to-noise ratio S/N ≈ 750 and 50, respectively, under illumination by using IR monochromator and globar as a thermal source.

  3. Study of the phase diagram of dense two-color QCD within lattice simulation

    CERN Document Server

    Braguta, V V; Kotov, A Yu; Molochkov, A V; Nikolaev, A A

    2016-01-01

    In this paper we carry out a low-temperature scan of the phase diagram of dense two-color QCD with $N_f=2$ quarks. The study is conducted using lattice simulation with rooted staggered quarks. At small chemical potential we observe the hadronic phase, where the theory is in a confining state, chiral symmetry is broken, the baryon density is zero and there is no diquark condensate. At the critical point $\\mu = m_{\\pi}/2$ we observe the expected second order transition to Bose-Einstein condensation of scalar diquarks. In this phase the system is still in confinement in conjunction with nonzero baryon density, but the chiral symmetry is restored in the chiral limit. We have also found that in the first two phases the system is well described by chiral perturbation theory. For larger values of the chemical potential the system turns into another phase, where the relevant degrees of freedom are fermions residing inside the Fermi sphere, and the diquark condensation takes place on the Fermi surface. In this phase t...

  4. Comparison of simulated and experimental 3D laser images using a GmAPD array: application to long range detection

    Science.gov (United States)

    Coyac, Antoine; Riviere, Nicolas; Hespel, Laurent; Briottet, Xavier

    2016-05-01

    In this paper, we show the feasibility and the benefit to use a Geiger-mode Avalanche Photo-Diode (GmAPD) array for long range detection, up to several kilometers. A simulation of a Geiger detection sensor is described, which is a part of our end-to-end laser simulator, to generate simulated 3D laser images from synthetic scenes. Resulting 3D point clouds have been compared to experimental acquisitions, performed with our GmAPD 3D camera on similar scenarios. An operational case of long range detection is presented: a copper cable outstretched above the ground, 1 kilometer away the experimental system and with a horizontal line-of-sight (LOS). The detection of such a small object from long distance observation strongly suggests that GmAPD focal plane arrays could be easily used for real-time 3D mapping or surveillance applications from airborne platforms, with good spatial and temporal resolutions.

  5. Underwater Laser-illuminated Range-gated Imaging Scaled by 22.5 cm ns-1 with Serial Targets

    Institute of Scientific and Technical Information of China (English)

    HE Duo-Min

    2004-01-01

    We have developed a novel target set to scale our Underwater Laser-illuminated Range-gated Imaging(ULRI)video system in a 3 m-tank with turbid water(attenuation coefficient 1.0 m-1). As light speed in water is 22.5 cm ns-1, the target set consists of a series of 3-bar targets at 22.5 cm intervals along the laser illumination direction, with the targets separated vertically. As a result, a sequence of good gated images, in steps of 1 ns delay, is presented, which is a revelation of the' sliced-view' phenomenon for ns-level range-gating in such a limited water body. The Depth of Gating(DOG)and DOG-profile of the URLI system are measured for the first time, which can be used for evaluating gating-performance efficiently.

  6. Prospects in the orbital and rotational dynamics of the Moon with the advent of sub-centimeter lunar laser ranging

    CERN Document Server

    Kopeikin, S M; Pavlis, D; Brumberg, V A; Escapa, A; Getino, J; Gusev, A; Müller, J; Ni, W -T; Petrova, N

    2007-01-01

    Lunar Laser Ranging (LLR) measurements are crucial for advanced exploration of the laws of fundamental gravitational physics and geophysics. Current LLR technology allows us to measure distances to the Moon with a precision approaching 1 millimeter. As NASA pursues the vision of taking humans back to the Moon, new, more precise laser ranging applications will be demanded, including continuous tracking from more sites on Earth, placing new CCR arrays on the Moon, and possibly installing other devices such as transponders, etc. Successful achievement of this goal strongly demands further significant improvement of the theoretical model of the orbital and rotational dynamics of the Earth-Moon system. This model should inevitably be based on the theory of general relativity, fully incorporate the relevant geophysical processes, lunar librations, tides, and should rely upon the most recent standards and recommendations of the IAU for data analysis. This paper discusses methods and problems in developing such a mat...

  7. Rate of change of the Quincy-Monument Peak baseline from a translocation analysis of Lageos laser range data

    Science.gov (United States)

    Stolz, A.; Bender, P. L.; Vincent, M. A.; Eanes, R. J.; Watkins, M. M.

    1989-01-01

    Translocation studies of Lageos laser range data from Quincy and Monument Peak in California observed during 1984-1987 suggest that plate tectonic motion across the San Andreas fault system in the direction of the baseline between the two stations is uniform at a rate of -30(+ or - 3) mm/yr. Changes in the components of the baseline vector were inferred from repeat determinations using the solutions from successive 0.5-year intervals. The changes in the vertical and transverse components of the Quincy-Monument Peak baseline are -0.4(+ or - 5) mm/yr and +14(+ or -5) mm/yr, respectively. The vertical component determinations attest to the height stability of the laser ranging method. Lageos measurements made from Quincy and Monument Peak before 1984 are inaccurate enough to limit their usefulness for plate tectonic studies.

  8. Real-time displacement measurement with large range and high accuracy using sinusoidal phase modulating laser diode interferometer

    Institute of Scientific and Technical Information of China (English)

    Guotian He; Xiangzhao Wang; Aijun Zeng; Feng Tang; Bingjie Huang

    2007-01-01

    To resolve the conflict of large measurement range and high accuracy in the existing real-time displacement measurement laser diode (LD) interferometers, a novel real-time displacement measurement LD interferometry is proposed and its measurement principle is analyzed. By use of a new phase demodulation algorithm and a new phase compensation lgorithm of real-time phase unwrapping, the measurement accuracy is improved, and the measurement range is enlarged to a few wavelengths. In experiments, the peak-to-peak amplitude of the speaker vibration was 2361.7 nm, and the repeatability was 2.56 nm. The measurement time was less than 26μs.

  9. Active Laser and Raman Materials for 1.3-5 Micron Spectral Range

    Science.gov (United States)

    2006-03-01

    1989, pp. 270 (in Russian) 31. Handbook of lasers with selected data on optical technology, Ed. R.J. Pressley, Chemical Rubber Co, Cleveland, 1971 32...decreasing from surface to volume. Black surface has high electric conductivity . The results of electron microanalysis indicate that color is connected with...effective samples purification from tungsten without it destroying. The dipping of green yttria compact into crumb from yttria particles was

  10. Method of calculating retroreflector-array transfer functions. [laser range finders

    Science.gov (United States)

    Arnold, D. A.

    1978-01-01

    Techniques and equations used in calculating the transfer functions to relate the observed return laser pulses to the center of mass of the Lageos satellite retroflector array, and for most of the retroreflector-equipped satellites now in orbit are described. The methods derived include the effects of coherent interference, diffraction, polarization, and dihedral-angle offsets. Particular emphasis is given to deriving expressions for the diffraction pattern and active reflecting area of various cube-corner designs.

  11. Micro-joule pico-second range Yb3+-doped fibre laser for medical applications in acupuncture

    Science.gov (United States)

    Alvarez-Chavez, J. A.; Rivera-Manrique, S. I.; Jacques, S. L.

    2011-08-01

    The work described here is based on the optical design, simulation and on-going implementation of a pulsed (Q-switch) Yb3+-doped, 1-um diffraction-limited fibre laser with pico-second, 10 micro-Joule-range energy pulses for producing the right energy pulses which could be of benefit for patients who suffer chronic headache, photophobia, and even nausea which could is sometimes triggered by a series of factors. The specific therapeutic effect known as acupunctural analgesia is the main objective of this medium-term project. It is a simple design on which commercially available software was employed for laser cavity design. Monte Carlo technique for skin light-transport, thermal diffusion and the possible thermal de-naturalization optical study and prediction will also be included in the presentation. Full optical characterization will be included and a complete set of recent results on the laser-skin interaction and the so called moxi-bustion from the laser design will be extensively described.

  12. Phase diagram of two-color QCD in a Dyson-Schwinger approach

    Energy Technology Data Exchange (ETDEWEB)

    Buescher, Pascal Joachim

    2014-04-28

    We investigate two-color QCD with N{sub f}=2 at finite temperatures and chemical potentials using a Dyson-Schwinger approach. We employ two different truncations for the quark loop in the gluon DSE: one based on the Hard-Dense/Hard-Thermal Loop (HDTL) approximation of the quark loop and one based on the back-coupling of the full, self-consistent quark propagator (SCQL). We compare results for the different truncations with each other as well as with other approaches. As expected, we find a phase dominated by the condensation of quark-quark pairs. This diquark condensation phase overshadows the critical end point and first-order phase transition which one finds if diquark condensation is neglected. The phase transition from the phase without diquark condensation to the diquark-condensation phase is of second order. We observe that the dressing with massless quarks in the HDTL approximation leads to a significant violation of the Silver Blaze property and to a too small diquark condensate. The SCQL truncation, on the other hand, is found to reproduce all expected features of the μ-dependent quark condensates. Moreover, with parameters adapted to the situation in other approaches, we also find good to very good agreement with model and lattice calculations in all quark quantities. We find indictions that the physics in recent lattice calculations is likely to be driven solely by the explicit chiral symmetry breaking. Discrepancies w.r.t. the lattice are, however, observed in two quantities that are very sensitive to the screening of the gluon propagator, the dressed gluon propagator itself and the phase-transition line at high temperatures.

  13. Lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Babichev, A. V.; Karachinsky, L. Ya.; Novikov, I. I. [Ioffe Institute (Russian Federation); Nikitina, E. V. [St. Petersburg Academic University (Russian Federation); Tchernycheva, M. [University Paris Sud XI, Institut d’Electronique Fondamentale (France); Sofronov, A. N.; Firsov, D. A.; Vorobjev, L. E. [Peter the Great St. Petersburg Polytechnic University (Russian Federation); Pikhtin, N. A.; Tarasov, I. S. [Ioffe Institute (Russian Federation)

    2015-11-15

    The lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping are demonstrated. The quantum-cascade laser heterostructure is grown by molecular-beam epitaxy technique. Despite the relatively short laser cavity length and high level of external loss the laser shows the lasing in the temperature range of 80–220 K. The threshold current density below 4 kA/cm{sup 2} at 220 K with the characteristic temperature T{sub 0} = 123 K was demonstrated.

  14. Characterization of timing jitter spectra in free-running mode-locked lasers with 340 dB dynamic range over 10 decades of Fourier frequency

    CERN Document Server

    Jung, Kwangyun

    2014-01-01

    We demonstrate a method that enables accurate timing jitter spectral density characterization of free-running mode-locked laser oscillators over more than 10-decade of Fourier frequency from mHz to tens MHz range. The method is based on analyzing both the input voltage noise to the slave laser and the output voltage noise from the balanced optical cross- correlator (BOC), when two mode-locked lasers are synchronized in repetition rate by the BOC. As a demonstration experiment, timing jitter spectrum of a free-running mode-locked Er-fiber laser with a dynamic range of >340 dB is measured over Fourier frequency ranging from 1 mHz to 38.5 MHz (Nyquist frequency). The demonstrated method can resolve different noise mechanisms that cause specific jitter characteristics in free-running mode-locked laser oscillators for a vast range of time scales from 1000-s.

  15. Study of the Wavelength Dependence in Laser Ablation of Advanced Ceramics and Glass-Ceramic Materials in the Nanosecond Range.

    Science.gov (United States)

    Sola, Daniel; Peña, Jose I

    2013-11-19

    In this work, geometrical dimensions and ablation yields as a function of the machining method and reference position were studied when advanced ceramics and glass-ceramic materials were machined with pulsed lasers in the nanosecond range. Two laser systems, emitting at 1064 and 532 nm, were used. It was shown that the features obtained depend on whether the substrate is processed by means of pulse bursts or by grooves. In particular, when the samples were processed by grooves, machined depth, removed volume and ablation yields reached their maximum, placing the sample out of focus. It was shown that these characteristics do not depend on the processing conditions, the wavelength or the optical configuration, and that this is intrinsic behavior of the processing method. Furthermore, the existence of a close relation between material hardness and ablation yields was demonstrated.

  16. Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Gangyi, E-mail: gangyi.xu@mail.sitp.ac.cn [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France); Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Li, Lianhe; Giles Davies, A.; Linfield, Edmund H. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS9 2JT (United Kingdom); Isac, Nathalie; Halioua, Yacine; Colombelli, Raffaele, E-mail: raffaele.colombelli@u-psud.fr [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France)

    2014-03-03

    We demonstrate efficient surface-emitting terahertz frequency quantum cascade lasers with continuous wave output powers of 20–25 mW at 15 K and maximum operating temperatures of 80–85 K. The devices employ a resonant-phonon depopulation active region design with injector, and surface emission is realized using resonators based on graded photonic heterostructures (GPHs). GPHs can be regarded as energy wells for photons and have recently been implemented through grading the period of the photonic structure. In this paper, we show that it is possible to keep the period constant and grade instead the lateral metal coverage across the GPH. This strategy ensures spectrally single-mode operation across the whole laser dynamic range and represents an additional degree of freedom in the design of confining potentials for photons.

  17. Selective excavation of human carious dentin using the nanosecond pulsed laser in 5.8-μm wavelength range

    Science.gov (United States)

    Kita, Tetsuya; Ishii, Katsunori; Yoshikawa, Kazushi; Yasuo, Kenzo; Yamamoto, Kazuyo; Awazu, Kunio

    Less-invasive treatment of caries has been needed in laser dentistry. Based on the absorption property of dentin substrates, 6 μm wavelength range shows specific absorptions and promising characteristics for the excavation. In our previous study, 5.8 μm wavelength range was found to be effective for selective excavation of carious dentin and restoration treatment using composite resin from the irradiation experiment with bovine sound and demineralized dentin. In this study, the availability of 5.8 μm wavelength range for selective excavation of human carious dentin was investigated for clinical application. A mid-infrared tunable nanosecond pulsed laser by difference-frequency generation was used for revealing the ablation property of human carious dentin. Irradiation experiments indicated that the wavelength of 5.85 μm and the average power density of 30 W/cm2 realized the selective excavation of human carious dentin, but ablation property was different with respect to each sample because of the different caries progression. In conclusion, 5.8 μm wavelength range was found to be effective for selective excavation of human carious dentin.

  18. Interpretation of laser/multi-sensor data for short range terrain modeling and hazard detection

    Science.gov (United States)

    Messing, B. S.

    1980-01-01

    A terrain modeling algorithm that would reconstruct the sensed ground images formed by the triangulation scheme, and classify as unsafe any terrain feature that would pose a hazard to a roving vehicle is described. This modeler greatly reduces quantization errors inherent in a laser/sensing system through the use of a thinning algorithm. Dual filters are employed to separate terrain steps from the general landscape, simplifying the analysis of terrain features. A crosspath analysis is utilized to detect and avoid obstacles that would adversely affect the roll of the vehicle. Computer simulations of the rover on various terrains examine the performance of the modeler.

  19. In-line process control for laser welding of titanium by high dynamic range ratio pyrometry and plasma spectroscopy

    Science.gov (United States)

    Lempe, B.; Taudt, C.; Baselt, T.; Rudek, F.; Maschke, R.; Basan, F.; Hartmann, P.

    2014-02-01

    The production of complex titanium components for various industries using laser welding processes has received growing attention in recent years. It is important to know whether the result of the cohesive joint meets the quality requirements of standardization and ultimately the customer requirements. Erroneous weld seams can have fatal consequences especially in the field of car manufacturing and medicine technology. To meet these requirements, a real-time process control system has been developed which determines the welding quality through a locally resolved temperature profile. By analyzing the resulting weld plasma received data is used to verify the stability of the laser welding process. The determination of the temperature profile is done by the detection of the emitted electromagnetic radiation from the material in a range of 500 nm to 1100 nm. As detectors, special high dynamic range CMOS cameras are used. As the emissivity of titanium depends on the wavelength, the surface and the angle of radiation, measuring the temperature is a problem. To solve these a special pyrometer setting with two cameras is used. That enables the compensation of these effects by calculating the difference between the respective pixels on simultaneously recorded images. Two spectral regions with the same emissivity are detected. Therefore the degree of emission and surface effects are compensated and canceled out of the calculation. Using the spatially resolved temperature distribution the weld geometry can be determined and the laser process can be controlled. The active readjustment of parameters such as laser power, feed rate and inert gas injection increases the quality of the welding process and decreases the number of defective goods.

  20. Power dependence of terahertz carrier frequency in a plasma-based two-color generation process

    Science.gov (United States)

    Zhao, Ji; Zhang, Liang-Liang; Luo, Yi-Man; Wu, Tong; Zhang, Cun-Lin; Zhao, Yue-Jin

    2014-12-01

    We conduct a frequency spectrum experiment to investigate terahertz (THz) emissions from laser-induced air plasma under different laser incident powers. The frequency spectra are measured using both air-biased-coherent detection and a Michelson interferometer. The red-shift of the THz pulse carrier frequency is observed as a response to increased pump power. These phenomena are related to plasma collisions and can be explained by the plasma collision model. Based on these findings, it is apparent that the tuning of the THz carrier frequency can be achieved through regulation of the pump beam.

  1. Investigation of soot by two-color four-wave mixing

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B.; Stampanoni-Panariello, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    A novel, non-intrusive technique has been used for the temporally resolved investigation of the interaction of laser radiation and soot in a flame. While there is a fairly good agreement between measurement and simulation remaining discrepancies indicate some shortcomings of the model employed. (author) 2 figs., 2 refs.

  2. Simulation of power – current characteristics of high-power semiconductor lasers emitting in the range 1.5 – 1.55 μm

    Energy Technology Data Exchange (ETDEWEB)

    Gorlachuk, P V; Ivanov, A V; Kurnosov, V D; Kurnosov, K V; Romantsevich, V I; Simakov, V A; Chernov, R V [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2014-02-28

    We report the simulation of power – current characteristics of high-power semiconductor lasers emitting in the range 1.5 – 1.55 μm. A technique is described which allows one to determine the thermal resistance and characteristic temperatures of a laser diode. The radiative and nonradiative carrier recombination rates are evaluated. Simulation results are shown to agree well with experimental data. (lasers)

  3. Double acousto-optic deflector system for increased scanning range of laser beams.

    Science.gov (United States)

    Kastelik, J-C; Dupont, S; Yushkov, K B; Molchanov, V Ya; Gazalet, J

    2017-09-01

    A new laser scanning system is presented based on two wide-band acousto-optic deflectors. The interaction medium is tellurium dioxide. Anisotropic interactions take place under two different tangential phase matching configurations in such a way that the acousto-optic bandwidths add up. We demonstrate the feasibility of such a cascade deflection system for the wavelength of λ=514nm. The total frequency bandwidth is Δf=100MHz, equally distributed between the two acousto-optic deflectors. The total angular scan at the output is Δθ=4.4° leading to 125 resolvable spots for a 1mm truncated Gaussian beam. Copyright © 2017. Published by Elsevier B.V.

  4. On the accuracy of lunar ephemerides using the data provided by the future Russian lunar laser ranging system

    Science.gov (United States)

    Vasilyev, M. V.; Yagudina, E. I.; Grishin, E. A.; Ivlev, O. A.; Grechukhin, I. A.

    2016-09-01

    The potential effect of the future Russian lunar laser ranging system (LLRS) on the accuracy of lunar ephemerides is discussed. In addition to the LLRS in Altai, several other observatories suitable for the LLRS installation are considered. The variation of accuracy of lunar ephemerides in the process of commissioning of new LLRS stations is estimated by mathematical modeling. It is demonstrated that the error in the determination of certain lunar ephemeris parameters may be reduced by up to 16% after seven years of operation of the Altai LLRS with a nearly optimal observational program.

  5. Development and analysis of a photon-counting three-dimensional imaging laser detection and ranging (LADAR) system.

    Science.gov (United States)

    Oh, Min Seok; Kong, Hong Jin; Kim, Tae Hoon; Jo, Sung Eun; Kim, Byung Wook; Park, Dong Jo

    2011-05-01

    In this paper, a photon-counting three-dimensional imaging laser detection and ranging (LADAR) system that uses a Geiger-mode avalanche photodiode (GAPD) of relatively short dead time (45 ns) is described. A passively Q-switched microchip laser is used as a laser source and a compact peripheral component interconnect system, which includes a time-to-digital converter (TDC), is set up for fast signal processing. The combination of a GAPD with short dead time and a TDC with a multistop function enables the system to operate in a single-hit or a multihit mode during the acquisition of time-of-flight data. The software for the three-dimensional visualization and an algorithm for the removal of noise are developed. For the photon-counting LADAR system, we establish a theoretical model of target-detection and false-alarm probabilities in both the single-hit and multihit modes with a Poisson statistic; this model provides the prediction of the performance of the system and a technique for the acquisition of a noise image with a GAPD. Both the noise image and the three-dimensional image of a scene acquired by the photon-counting LADAR system during the day are presented.

  6. 基于彩色CCD的双色与三色比色测温法比较研究%Comparative Study on Two-Color and Three-Color Colorimetric Temperature Measurement Based on Colored CCD

    Institute of Scientific and Technical Information of China (English)

    孙元; 彭小奇

    2015-01-01

    双色与三色比色测温是彩色CCD辐射测温常用方法。通过理论分析和实验研究,分别从测温动态范围和测温精度两方面对双色法和三色法进行了比较研究。研究发现,在光圈快门组合保持不变的条件下,选取红、绿双色进行比色测温具有较宽的测温动态范围;在对辐射体做灰体假设的情况下,三色测温方法具有更高的测温精度。提出了构建一种可切换测温方法的统一测温硬件平台,统一测温平台综合了双色法和三色法两者的优点,可同时满足更宽的测温动态范围和更高的测温精度的要求,应用灵活。%The two-color and three-color colorimetric temperature measurements are major methods of the colored CCD-based radiation thermometry. The dynamic range and temperature measurement accuracy of the two-color and three-color thermometry are analyzed and compared respectively. The theory analysis and experimental results show that the two-color thermometry using red-green colors has much wider dynamic range than the three-color thermome⁃try in the combination of an aperture and shutter. In the other hand,the three-color thermometry has higher accura⁃cy than the two-color method when the radiator is assumed as a gray-body. Finally,the general temperature measure⁃ment platform flexibly switching the two-color and the three-color thermometry is proposed. The measurement plat⁃form combines the advantages of the two-color and three-color thermometry,which meets the requirements of wide dynamic range and high measurement accuracy.

  7. Tuning range and output power optimization of an external-cavity GaN diode laser at 455  nm.

    Science.gov (United States)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-03-20

    In this paper we discuss how different feedback gratings affect the tuning range and the output power of external feedback diode laser systems. A tunable high-power narrow-spectrum external-cavity diode laser system around 455 nm is investigated. The laser system is based on a high-power GaN diode laser in a Littrow external-cavity. Both a holographic diffraction grating and a ruled diffraction grating are used as feedback elements in the external cavity. The output power, spectral bandwidth, and tunable range of the external cavity diode laser system are measured and compared with the two gratings at different injected currents. When the holographic grating is used, the laser system can be tuned over a range of 1.4 nm with an output power around 530 mW. When the ruled grating is used, the laser system can be tuned over a range of 6.0 nm with an output power around 80 mW. The results can be used as a guide for selecting gratings for external-cavity diode lasers for different requirements.

  8. High-Resolution Digital Two-Color PIV for Turbomachinery Flows

    Science.gov (United States)

    Copenhaver, W.; Gogineni, S.; Goss, L.

    1996-11-01

    Turbomachinery flows are inherently unsteady. However, steady design methods are currently used to develop turbomachinery, with the lack of basic understanding of unsteady effects being compensated by use of extensive empirical correlations. Conventional laser anemometry provides quantitative evidence of unsteady effects in turbomachinery but is limited in fully exploring this phenomenon. The PIV technique holds great promise for elucidating unsteady flow mechanisms in turbomachinery if obstacles to its application in a transonic turbomachine can be overcome. Implementation involves critical issues such as tracer seeding and optical access for transmitter and receiver. Initially, an 18-in.-dia. axial fan is used to explore these issues. One optical configuration considered is the fiber-optic fanning light sheet in conjunction with high-power pulsed lasers. Instantaneous velocity measurements are made between blades at different spanwise locations.

  9. Wireless Laser Range Finder System for Vertical Displacement Monitoring of Mega-Trusses during Construction

    Directory of Open Access Journals (Sweden)

    Hyo Seon Park

    2013-05-01

    Full Text Available As buildings become increasingly complex, construction monitoring using various sensors is urgently needed for both more systematic and accurate safety management and high-quality productivity in construction. In this study, a monitoring system that is composed of a laser displacement sensor (LDS and a wireless sensor node was proposed and applied to an irregular building under construction. The subject building consists of large cross-sectional members, such as mega-columns, mega-trusses, and edge truss, which secured the large spaces. The mega-trusses and edge truss that support this large space are of the cantilever type. The vertical displacement occurring at the free end of these members was directly measured using an LDS. To validate the accuracy and reliability of the deflection data measured from the LDS, a total station was also employed as a sensor for comparison with the LDS. In addition, the numerical simulation result was compared with the deflection obtained from the LDS and total station. Based on these investigations, the proposed wireless displacement monitoring system was able to improve the construction quality by monitoring the real-time behavior of the structure, and the applicability of the proposed system to buildings under construction for the evaluation of structural safety was confirmed.

  10. Exhaled air analysis using wideband wave number tuning range infrared laser photoacoustic spectroscopy

    Science.gov (United States)

    Kistenev, Yury V.; Borisov, Alexey V.; Kuzmin, Dmitry A.; Penkova, Olga V.; Kostyukova, Nadezhda Y.; Karapuzikov, Alexey A.

    2017-01-01

    The infrared laser photoacoustic spectroscopy (LPAS) and the pattern-recognition-based approach for noninvasive express diagnostics of pulmonary diseases on the basis of absorption spectra analysis of the patient's exhaled air are presented. The study involved lung cancer patients (N=9), patients with chronic obstructive pulmonary disease (N=12), and a control group of healthy, nonsmoking volunteers (N=11). The analysis of the measured absorption spectra was based at first on reduction of the dimension of the feature space using principal component analysis; thereafter, the dichotomous classification was carried out using the support vector machine. The gas chromatography-mass spectrometry method (GC-MS) was used as the reference. The estimated mean value of the sensitivity of exhaled air sample analysis by the LPAS in dichotomous classification was not less than 90% and specificity was not less than 69%; the analogous results of analysis by GC-MS were 68% and 60%, respectively. Also, the approach to differential diagnostics based on the set of SVM classifiers usage is presented.

  11. Two-color, laser excitation improves temporal resolution for detecting the dynamic, plasmonic coupling between metallic nanoparticles.

    Science.gov (United States)

    Wiener, Diane M; Lionberger, Troy A

    2013-05-21

    The ability of two, scattering gold nanoparticles (GNPs) to plasmonically couple in a manner that is dependent on the interparticle separation has been exploited to measure nanometer-level displacements. However, despite broad applicability to monitoring biophysical dynamics, the long time scales (dynamic molecular processes, generally occurring over several milliseconds. Here, we introduce a new technique intended to overcome this technical limitation: ratiometric analysis using monochromatic, evanescent darkfield illumination (RAMEDI). As a proof-of-principle, we monitored dynamic, plasmonic coupling arising from the binding of single biotin- and neutravidin-GNPs with a temporal resolution of 38 ms. We also show that the observable bandwidth is extendable to faster time scales by demonstrating that RAMEDI is capable of achieving a signal-to-noise ratio greater than 20 from individual GNPs observed with 200 Hz bandwidth.

  12. Density profiles of small Dirac operator eigenvalues for two color QCD at nonzero chemical potential compared to matrix models

    Energy Technology Data Exchange (ETDEWEB)

    Akemann, Gernot [Service de Physique Theorique, CEA/DSM/SPhT Saclay, Unite associee CNRS/SPM/URA 2306, F-91191 Gif-sur-Yvette Cedex (France); Department of Mathematical Sciences, Brunel University West London, Uxbridge, UB8 3PH (United Kingdom); Bittner, Elmar [Institut fuer Theoretische Physik, Universitaet Leipzig, Augustplatz 10/11, D-04109 Leipzig (Germany); Lombardo, Maria-Paola [INFN-Laboratori Nazionali di Frascati, I-00044 Frascati (Italy); Markum, Harald [Atominstitut, Technische Universitaet Wien, A-1040 Vienna (Austria); Pullirsch, Rainer [Atominstitut, Technische Universitaet Wien, A-1040 Vienna (Austria)

    2005-03-15

    We investigate the eigenvalue spectrum of the staggered Dirac matrix in two color QCD at finite chemical potential. The profiles of complex eigenvalues close to the origin are compared to a complex generalization of the chiral Gaussian Symplectic Ensemble, confirming its predictions for weak and strong non-Hermiticity. They differ from the QCD symmetry class with three colors by a level repulsion from both the real and imaginary axis.

  13. Ultra-broad range organic solid-state laser from a dye-doped holographic grating quasi-waveguide configuration

    Science.gov (United States)

    Liu, Minghuan; Liu, Yonggang; Peng, Zenghui; Mu, Quanquan; Cao, Zhaoliang; Lu, Xinghai; Ma, Ji; Xuan, Li

    2017-08-01

    This paper reports the ultra-broad 149.1 nm lasing emission from 573.2 to 722.3 nm using a simple [4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran] (DCM)-doped holographic polymer-dispersed liquid crystal (HPDLC) grating quasi-waveguide configuration by varying the grating period. The lasing emission beams show s-polarization property. The quasi-waveguide structure, which contained the cover glass, the DCM-doped HPDLC grating, the semiconducting polymer film poly[-methoxy-5-(2‧-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV), and the substrate were confirmed to decrease lasing threshold and broaden lasing wavelength. The operational lifetime of the device is 240 000 pulses, which corresponds to an overall laser duration of more than 6 h at a repetition rate of 10 Hz. In addition, the dual-wavelength lasing range from the 8th and 9th order is over 40 nm. The electrical tunability of the dual-wavelength lasing emission is over 1 nm. The experimental results facilitated the decreased lasing threshold and broadened lasing wavelength range of organic solid-state lasers.

  14. Documenting a Complex Modern Heritage Building Using Multi Image Close Range Photogrammetry and 3d Laser Scanned Point Clouds

    Science.gov (United States)

    Vianna Baptista, M. L.

    2013-07-01

    Integrating different technologies and expertises help fill gaps when optimizing documentation of complex buildings. Described below is the process used in the first part of a restoration project, the architectural survey of Theatre Guaira Cultural Centre in Curitiba, Brazil. To diminish time on fieldwork, the two-person-field-survey team had to juggle, during three days, the continuous artistic activities and performers' intense schedule. Both technologies (high definition laser scanning and close-range photogrammetry) were used to record all details in the least amount of time without disturbing the artists' rehearsals and performances. Laser Scanning was ideal to record the monumental stage structure with all of its existing platforms, light fixtures, scenery walls and curtains. Although scanned with high-definition, parts of the exterior façades were also recorded using Close Range Photogrammetry. Tiny cracks on the marble plaques and mosaic tiles, not visible in the point clouds, were then able to be precisely documented in order to create the exterior façades textures and damages mapping drawings. The combination of technologies and the expertise of service providers, knowing how and what to document, and what to deliver to the client, enabled maximum benefits to the following restoration project.

  15. Photo-electron momentum distribution and electron localization studies from laser-induced atomic and molecular dissociations

    Science.gov (United States)

    Ray, Dipanwita

    The broad objective of ultrafast strong-field studies is to be able to measure and control atomic and molecular dynamics on a femtosecond timescale. This thesis work has two major themes: (1) Study of high-energy photoelectron distributions from atomic targets. (2) Electron localization control in atomic and molecular reactions using shaped laser pulses. The first section focuses on the study of photoelectron diffraction patterns of simple atomic targets to understand the target structure. We measure the full vector momentum spectra of high energy photoelectrons from atomic targets (Xe, Ar and Kr) generated by intense laser pulses. The target dependence of the angular distribution of the highest energy photoelectrons as predicted by Quantitative Rescattering Theory (QRS) is explored. More recent developments show target structure information can be retrieved from photoelectrons over a range of energies, from 4Up up to 10Up, independent of the peak intensity at which the photoelectron spectra have been measured. Controlling the fragmentation pathways by manipulating the pulse shape is another major theme of ultrafast science today. In the second section we study the asymmetry of electron (and ion) emission from atoms (and molecules) by interaction with asymmetric pulses formed by the superposition of two colors (800 & 400 nm). Xe electron momentum spectra obtained as a function of the two-color phase exhibit a pronounced asymmetry. Using QRS theory we can analyze this asymmetric yield of the high energy photoelectrons to determine accurately the laser peak intensity and the absolute phase of the two-color electric field. This can be used as a standard pulse calibration method for all two-color studies. Experiments showing strong left-right asymmetry in D+ ion yield from D2 molecules using two-color pulses is also investigated. The asymmetry effect is found to be very ion-energy dependent.

  16. Sampled grating tunable twin-guide laser diodes with wide tuning range (40 nm) and large output power (10 mW)

    Science.gov (United States)

    Todt, R.; Jacke, T.; Meyer, R.; Adler, J.; Laroy, R.; Morthier, G.; Amann, M.-C.

    2006-03-01

    The sampled grating tunable twin-guide (SG-TTG) laser diode is a DFB-like tunable laser that employs Vernier-effect tuning to achieve wide wavelength tuning. In contrast to most other monolithic widely tunable lasers (which are usually DBR-type lasers), a phase tuning section is not needed and, hence, the SG-TTG laser requires at least one tuning current less than comparable devices.The devices provide full wavelength coverage over a 40 nm-broad tuning range that is centered at 1.54 μm. Its tuning behavior is quasi-continuous with up to 8.2 nm broad continuous tuning regions. High side-mode suppression (SMSR 35 dB) as well as large output power (P 10 mW) are obtained over the whole wavelength range from 1520.5 to 1561.5 nm.

  17. Two-Color Coherent Control of Femtosecond Above-Threshold Photoemission from a Tungsten Nanotip

    Science.gov (United States)

    Förster, Michael; Paschen, Timo; Krüger, Michael; Lemell, Christoph; Wachter, Georg; Libisch, Florian; Madlener, Thomas; Burgdörfer, Joachim; Hommelhoff, Peter

    2016-11-01

    We demonstrate coherent control of multiphoton and above-threshold photoemission from a single solid-state nanoemitter driven by a fundamental and a weak second harmonic laser pulse. Depending on the relative phase of the two pulses, electron emission is modulated with a contrast of the oscillating current signal of up to 94%. Electron spectra reveal that all observed photon orders are affected simultaneously and similarly. We confirm that photoemission takes place within 10 fs. Accompanying simulations indicate that the current modulation with its large contrast results from two interfering quantum pathways leading to electron emission.

  18. Two-color coherent control of femtosecond above-threshold photoemission from a tungsten nanotip

    CERN Document Server

    Förster, Michael; Krüger, Michael; Lemell, Christoph; Wachter, Georg; Libisch, Florian; Madlener, Thomas; Burgdörfer, Joachim; Hommelhoff, Peter

    2016-01-01

    We demonstrate coherent control of multiphoton and above-threshold photoemission from a single solid-state nanoemitter driven by a fundamental and a weak second harmonic laser pulse. Depending on the relative phase of the two pulses, electron emission is modulated with a visibility of up to 94%. Electron spectra reveal that all observed photon orders are affected simultaneously and similarly. We confirm that photoemission takes place within 10 fs. Accompanying simulations indicate that the current modulation with its large contrast results from two interfering quantum pathways leading to electron emission.

  19. Ground Based Free Electron Laser Technology Integration Experiment, White Sands Missile Range, New Mexico

    Science.gov (United States)

    1987-01-01

    would preclude interference with televisions , radios and computer equipment operated in the area around WSMR. Warning signs will be posted at the...canadensis mexicana ); (2) black-tailed prairie dog (Cynonmys ludovicianus); (3) Colorado chipmunk (Eutamias quadrivittatus australis); (4) White Sands pupfish...by GBFEL TIE equipment, it could disturb local television and radio receivers. Since the GBFEL TIE will be located on White Sands Missile Range (WSMR

  20. Optimization of a Quantum Cascade Laser Operating in the Terahertz Frequency Range Using a Multiobjective Evolutionary Algorithm

    Science.gov (United States)

    2004-06-01

    laser fundamentals , semiconductors, quantum wells and finally ending with a discussion of generic QC lasers. With the a priori knowledge that...quantum cascade laser structure and operation. It begins, in Chapter 2, with a discussion of the atom, continus with laser fundamentals , semiconductors...Aerospace Engineering, Arizona State University. 102 15. Chow, W. W. and Koch, S. W. Semiconductor- Laser Fundamentals . New York: Springer-Verlag

  1. Note: Inter-satellite laser range-rate measurement by using digital phase locked loop.

    Science.gov (United States)

    Liang, Yu-Rong; Duan, Hui-Zong; Xiao, Xin-Long; Wei, Bing-Bing; Yeh, Hsien-Chi

    2015-01-01

    This note presents an improved high-resolution frequency measurement system dedicated for the inter-satellite range-rate monitoring that could be used in the future's gravity recovery mission. We set up a simplified common signal test instead of the three frequencies test. The experimental results show that the dominant noises are the sampling time jitter and the thermal drift of electronic components, which can be reduced by using the pilot-tone correction and passive thermal control. The improved noise level is about 10(-8) Hz/Hz(1/2)@0.01Hz, limited by the signal-to-noise ratio of the sampling circuit.

  2. Comparison of soot formation for diesel and jet-a in a constant volume combustion chamber using two-color pyrometry

    KAUST Repository

    Jing, Wei

    2014-04-01

    The measurement of the two-color line of sight soot and KL factor for NO.2 diesel and jet-A fuels was conducted in an optical constant volume combustion chamber by using a high speed camera under 1000 K ambient temperature and varied oxygen concentration conditions. The ambient conditions were set as follows: four oxygen cases including 10%, 15%, 18% and 21% at 1000 K ambient temperature. KL factor and soot temperature were determined based on the two-color pyrometry technique using two band-pass filters with wavelengths of 650 nm and 550 nm. The results show that low soot temperature is observed in the upstream inner flame along the centerline, which is surrounded by high soot temperature regions, and a high KL factor is found in the same region with a low soot temperature. The results under different times suggest that soot temperature is higher for high O2 conditions during the entire flame development; meanwhile, both integrated KL factor and soot area decrease with the increase of O2 concentration. The two fuels share a similar trend of soot temperature and KL factor, however, diesel flame has a higher soot temperature and a larger high soot temperature area compared to jet-A flame. On the other hand, diesel flame shows a lower soot level during the quasi-steady state with a higher total soot level at the end of the combustion under low O2 conditions. A lower O2 concentration range from 10% to 15% is expected to have the possibility to achieve a simultaneous reduction of soot and NOx in sooting flames under the 1000 K ambient temperature condition. Copyright © 2014 SAE International.

  3. Two-color photoionization of calcium using SHG and LED light

    CERN Document Server

    Schuck, C; Almendros, M; Hennrich, M; Eschner, J

    2009-01-01

    We present a photoionization method to load single 40Ca ions in a linear Paul trap from an atomic beam. Neutral Ca I atoms are resonantly excited from the ground state to the intermediate 4s4p 1P_1-level using coherent 423nm radiation produced by single-pass second harmonic generation in a periodically poled KTiOPO_4 crystal pumped with an 120mW extended cavity diode laser. Ionization is then attained with a high-power light emitting diode imaged to the trap center, using an appropriately designed optical system composed of standard achromatic doublet lenses. The setup simplifies previous implementations at similar efficiency, and it hardly requires any maintenance at all.

  4. Frequency tripled 1542 nm telecom laser diode stabilized to iodine hyperfine line in the 10-15 range

    CERN Document Server

    Philippe, Charles; Holleville, David; Lours, Michel; Minh-Pham, Tuam; Hrabina, Jan; Burck, Frederic Du; Wolf, Peter; Acef, Ouali

    2016-01-01

    We report on telecom laser frequency stabilization to narrow iodine hyperfine line in the green range of the optical domain, after a frequency tripling process using two nonlinear PPLN crystals. We have generated up to 300 mW optical power in the green (P3w), from 800 mW of infrared power (Pw). This result corresponds to an optical conversion efficiency eta= P3w/Pw ~ 36 %. To our knowledge, this is the best value ever demonstrated for a CW frequency tripling process. We have used a narrow linewidth iodine hyperfine line (component a1 of the 127I2 R 35 (44-0) line) to stabilize the IR laser yielding to frequency stability of 4.8x10-14 t-1/2 with a minimum of 6x10-15 reached after 50 s of integration time. The whole optical setup is very compact and mostly optically fibered. This approach opens the way for efficient and elegant architecture development for space applications as one of several potential uses.

  5. Development of Ultrashort Pulse Lasers and Their Applications to Ultrafast Spectroscopy in the Visible and NIR Ranges

    Science.gov (United States)

    Kobayashi, Takayoshi

    2016-07-01

    The use of ultrafast spectroscopy to gain detailed information about nonlinear processes can disclose the key physical mechanisms in the processes. The information promises to be a useful means to enhance the necessary nonlinearity for optical devices such as optical switches and optical manipulations of quantum states. Our group has generated stable visible to near-infrared laser pulses with a sub-5-fs duration using a non-collinear optical parametric amplifier. We also developed a detection system composed of 128 lock-in detectors, which provides an indispensable means of obtaining ultrafast nonlinear responses simultaneously in a very broad spectral range. The developed ultrashort pulse laser is used to study the electronic relaxation and molecular vibration dynamics in molecular systems through the interaction of the ultrashort pulses with the systems. Ultrashort pulses can stimulate Raman scattering in a molecular system. Observed time-resolved spectrum was analyzed to separate the electronic and vibrational contributions to the transient difference absorbance. The probe wavelength dependence of the vibrational amplitude is explained in terms of the coupling between the two pairing components among the pump field, Stokes field, anti-Stokes field, and coherent vibrational coordinates.

  6. Development of a Compton Camera for Online Range Monitoring of Laser-Accelerated Proton Beams via Prompt-Gamma Detection

    Directory of Open Access Journals (Sweden)

    Thirolf P.G.

    2014-03-01

    Full Text Available Presently large efforts are conducted in Munich towards the development of proton beams for bio-medical applications, generated via the technique of particle acceleration from high-power, short-pulse lasers. While so far mostly offline diagnostics tools are used in this context, we aim at developing a reliable and accurate online range monitoring technique, based on the position-sensitive detection of prompt γ rays emitted from nuclear reactions between the proton beam and the biological sample. For this purpose, we develop a Compton camera, designed to be able to track not only the Compton scattering of the primary photon, but also to detect the secondary Compton electron, thus reducing the Compton cone to an arc segment and by this increasing the source reconstruction efficiency. Design specifications and the status of the protype system are discussed.

  7. Design concepts of monolithic metamorphic vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Karachinsky, L. Ya.; Novikov, I. I.; Babichev, A. V.; Nevedomskiy, V. N. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Bugrov, V. E. [ITMO University (Russian Federation)

    2015-11-15

    Possible design concepts for long-wavelength vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range on GaAs substrates are suggested. It is shown that a metamorphic GaAs–InGaAs heterostructure with a thin buffer layer providing rapid transition from the lattice constant of GaAs to that of In{sub x}Ga{sub 1–x}As with an indium fraction of x < 0.3 can be formed by molecular-beam epitaxy. Analysis by transmission electron microscopy demonstrated the effective localization of mismatch dislocations in the thin buffer layer and full suppression of their penetration into the overlying InGaAs metamorphic layer.

  8. Multi-Range Conditional Random Field for Classifying Railway Electrification System Objects Using Mobile Laser Scanning Data

    Directory of Open Access Journals (Sweden)

    Jaewook Jung

    2016-12-01

    Full Text Available Railways have been used as one of the most crucial means of transportation in public mobility and economic development. For safe railway operation, the electrification system in the railway infrastructure, which supplies electric power to trains, is an essential facility for stable train operation. Due to its important role, the electrification system needs to be rigorously and regularly inspected and managed. This paper presents a supervised learning method to classify Mobile Laser Scanning (MLS data into ten target classes representing overhead wires, movable brackets and poles, which are key objects in the electrification system. In general, the layout of the railway electrification system shows strong spatial regularity relations among object classes. The proposed classifier is developed based on Conditional Random Field (CRF, which characterizes not only labeling homogeneity at short range, but also the layout compatibility between different object classes at long range in the probabilistic graphical model. This multi-range CRF model consists of a unary term and three pairwise contextual terms. In order to gain computational efficiency, MLS point clouds are converted into a set of line segments to which the labeling process is applied. Support Vector Machine (SVM is used as a local classifier considering only node features for producing the unary potentials of the CRF model. As the short-range pairwise contextual term, the Potts model is applied to enforce a local smoothness in the short-range graph; while long-range pairwise potentials are designed to enhance the spatial regularities of both horizontal and vertical layouts among railway objects. We formulate two long-range pairwise potentials as the log posterior probability obtained by the naive Bayes classifier. The directional layout compatibilities are characterized in probability look-up tables, which represent the co-occurrence rate of spatial relations in the horizontal and vertical

  9. Development of a novel two color tracer perfusion technique for the hydrodynamic study of aqueous outflow in bovine eyes

    Institute of Scientific and Technical Information of China (English)

    ZHU Jing-yin; YE Wen; GONG Hai-yan

    2010-01-01

    Background Elevation of intraocular pressure is usually associated with primary open angle glaucoma and caused by increased outflow resistance. A two-color fluorescent tracer technique was developed to investigate the hydrodynamics of aqueous humor outflow with changing intraocular pressure within the same eye, to better understand the relationship between outflow facility and effective filtration area. Methods Eighteen enucleated bovine eyes were first perfused at 30 mmHg with Dulbecco's phosphate-buffered saline containing 5.5 mmol/L D-glucose. After a stable baseline facility, red fluorescent microspheres (0.5 μm, 0.002% v/v) were exchanged and perfused. Eyes in the one-color control group (n=6) were immediately perfused with fixative. In the experimental group (n=6), eyes were perfused with green tracer after intraocular pressure reduced to 7 mmHg, while in the two-color control group (n=6), eyes were perfused with green tracer with intraocular pressure remaining at 30 mmHg. All 12 eyes were then perfusion-fixed. Outflow facility was continuously recorded in all eyes. Confocal images were taken along the inner wall of the aqueous plexus and the percent of the effective filtration length (PEFL; length of inner wall exhibiting tracer labeling/total length of inner wall) was measured. The relationships between outflow facility and PEFL were analyzed statistically. Results No significant differences were found in baseline facilities (ulmin~(-1)·mmHg~(-1)) among the three groups (the experimental group: 0.93 0.12; the two-color control group: 0.90 0.19; the one-color control group: 0.98 0.13). In the experimental group, the outflow facility was significantly higher at 7 mmHg (4.29±1.01) than that at 30 mmHg (1.90±0.67, P <0.001), which corresponded to a significant increase in the PEFL at 7 mmHg (54.70±8.42) from that at 30 mmHg ((11.76±4.56)%, P<0.001). The PEFL labeled by red fluorescent microspheres in the experimental group ((11.76±4.56)%) showed no

  10. Two color interferometric electron density measurement in an axially blown arc

    Science.gov (United States)

    Stoller, Patrick; Carstensen, Jan; Galletti, Bernardo; Doiron, Charles; Sokolov, Alexey; Salzmann, René; Simon, Sandor; Jabs, Philipp

    2016-09-01

    High voltage circuit breakers protect the power grid by interrupting the current in case of a short circuit. To do so an arc is ignited between two contacts as they separate; transonic gas flow is used to cool and ultimately extinguish the arc at a current-zero crossing of the alternating current. A detailed understanding of the arc interruption process is needed to improve circuit breaker design. The conductivity of the partially ionized gas remaining after the current-zero crossing, a key parameter in determining whether the arc will be interrupted or not, is a function of the electron density. The electron density, in turn, is a function of the detailed dynamics of the arc cooling process, which does not necessarily occur under local thermodynamic equilibrium (LTE) conditions. In this work, we measure the spatially resolved line-integrated index of refraction in a near-current-zero arc stabilized in an axial flow of synthetic air with two nanosecond pulsed lasers at wavelengths of 532 nm and 671 nm. Generating a stable, cylindrically symmetric arc enables us to determine the three-dimensional index of refraction distribution using Abel inversion. Due to the wavelength dependence of the component of the index of refraction related to the free electrons, the information at two different wavelengths can be used to determine the electron density. This information allows us to determine how important it is to take into account non-equilibrium effects for accurate modeling of the physics of decaying arcs.

  11. Stimulated emission pumping of NH in flames by using two-color resonant four-wave mixing

    Energy Technology Data Exchange (ETDEWEB)

    Radi, P.P.; Frey, H.M.; Mischler, B.; Tzannis, A.P.; Beaud, P.; Gerber, T. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    In this work we examine the analytical potential of two-color resonant four-wave mixing for the determination and characterization of trace elements in a combustion environment. Experimental results for NH in flames at atmospheric pressure are presented. The selectivity of the technique is used to simplify the Q-branch region of the (0-0)A{sup 3}{Pi}-X{sup 3}{Sigma} vibronic transition of NH. In addition, we demonstrate that the technique is sensitive to state changing collisions. (author) 2 figs., 5 refs.

  12. Efficient generation of isolated attosecond pulses with high beam-quality by two-color Bessel-Gauss beams

    CERN Document Server

    Wang, Zhe; Zhang, Qingbin; Wang, Shaoyi; Lu, Peixiang

    2011-01-01

    The generation of isolated attosecond pulses with high efficiency and high beam quality is essential for attosec- ond spectroscopy. We numerically investigate the supercontinuum generation in a neutral rare-gas medium driven by a two-color Bessel-Gauss beam. The results show that an efficient smooth supercontinuum in the plateau is obtained after propagation, and the spatial profile of the generated attosecond pulse is Gaussian-like with the divergence angle of 0.1 degree in the far field. This bright source with high beam quality is beneficial for detecting and controlling the microscopic processes on attosecond time scale.

  13. Laser-driven plasma wakefield electron acceleration and coherent femtosecond pulse generation in X-ray and gamma ranges

    Science.gov (United States)

    Trunov, V. I.; Lotov, K. V.; Gubin, K. V.; Pestryakov, E. V.; Bagayev, S. N.; Logachev, P. V.

    2017-01-01

    The laser wakefield acceleration (LWFA) of electrons in capillaries and gas jets followed by inverse Compton scattering of high intensity femtosecond laser pulses is discussed. The drive and scattered pulses will be produced by the two-channel multi-terawatt laser system developed in ILP SB RAS.

  14. Simulation of laser propagation through a three-layer human skin model in the spectral range from 1000 to 1900 nm

    Science.gov (United States)

    Nasouri, Babak; Murphy, Thomas E.; Berberoglu, Halil

    2014-07-01

    For understanding the mechanisms of low-level laser/light therapy (LLLT), accurate knowledge of light interaction with tissue is necessary. We present a three-dimensional, multilayer reduced-variance Monte Carlo simulation tool for studying light penetration and absorption in human skin. Local profiles of light penetration and volumetric absorption were calculated for uniform as well as Gaussian profile beams with different spreads over the spectral range from 1000 to 1900 nm. The results showed that lasers within this wavelength range could be used to effectively and safely deliver energy to specific skin layers as well as achieve large penetration depths for treating deep tissues, without causing skin damage. In addition, by changing the beam profile from uniform to Gaussian, the local volumetric dosage could increase as much as three times for otherwise similar lasers. We expect that this tool along with the results presented will aid researchers in selecting wavelength and laser power in LLLT.

  15. Simulation of laser propagation through a three-layer human skin model in the spectral range from 1000 to 1900 nm.

    Science.gov (United States)

    Nasouri, Babak; Murphy, Thomas E; Berberoglu, Halil

    2014-01-01

    For understanding the mechanisms of low-level laser/light therapy (LLLT), accurate knowledge of light interaction with tissue is necessary. We present a three-dimensional, multilayer reduced-variance Monte Carlo simulation tool for studying light penetration and absorption in human skin. Local profiles of light penetration and volumetric absorption were calculated for uniform as well as Gaussian profile beams with different spreads over the spectral range from 1000 to 1900 nm. The results showed that lasers within this wavelength range could be used to effectively and safely deliver energy to specific skin layers as well as achieve large penetration depths for treating deep tissues, without causing skin damage. In addition, by changing the beam profile from uniform to Gaussian, the local volumetric dosage could increase as much as three times for otherwise similar lasers. We expect that this tool along with the results presented will aid researchers in selecting wavelength and laser power in LLLT.

  16. Use of a Novel Two Color PALM Method to Examine Structural Properties of Drp1 Helical Rings during Mammalian Mitochondrial Fission In Situ

    Science.gov (United States)

    Rosenbloom, Alyssa Blair

    In this thesis, we accomplish two goals: 1) we develop a novel two color photoactivatable light microscopy (PALM) method for imaging in mammalian cells and 2) we explore our original biological question and discern the structural properties of the Drp1 helical ring during fission. We established that mitochondrial membranes can be distinguished with the available photoactivatable fluorescent protein mEos2. However, we were not able to use any of the published photoactivatable and photoswitchable green fluorescent proteins, predominantly because of an inability to identify individual fluorescent events due to rapidity of the photoswitiching. Based on published crystal structures, we created novel Dronpa variants with increasing steric hindrance around the chromophore, likely partially inhibiting the isomerization. We replaced Val157 with isoleucine, leucine, or phenyalanine. DronpaV157F showed no fluorescence and was discarded. DronpaV157I and DronpaV157L showed photoswitchable green fluorescence, with individual fluorescent events that were more easily discerned. DronpaV157L in particular had bright fluorescent events that were well separated when imaged in mammalian cells at 20 Hz. We named this new variant rsKame. Using PALM we successfully imaged rsKame expressed and localized to the mammalian mitochondrial inner membrane. With the novel photoswitchable fluorescent protein, rsKame, available, we returned to the development of a novel two color PALM method. We chose PAmCherry1 as the partner for rsKame since PAmCherry1 has distinct and well separated excitation/emission spectra from rsKame and is not activated by low 405 nm laser power density. We first imaged rsKame with 405 nm activation at (0.61 mW/mm2) and 488 nm activation/excitation (5.87 W/mm 2) to completion. We then imaged PAmCherry1 with increasing 405 nm activation (0.6-6.0 W/mm2) and 561 nm excitation (22 W/mm 2). With the novel PALM imaging method, we labeled the inner and outer mitochondrial

  17. Compact fixed wavelength femtosecond oscillators as an add-on for tunable Ti:sapphire lasers extend the range of applications towards multimodal imaging and optogenetics

    Science.gov (United States)

    Hakulinen, T.; Klein, J.

    2016-03-01

    Two-photon (2P) microscopy based on tunable Ti:sapphire lasers has become a widespread tool for 3D imaging with sub-cellular resolution in living tissues. In recent years multi-photon microscopy with simpler fixed-wavelength femtosecond oscillators using Yb-doped tungstenates as gain material has raised increasing interest in life-sciences, because these lasers offer one order of magnitude more average power than Ti:sapphire lasers in the wavelength range around 1040 nm: Two-photon (2P) excitation of mainly red or yellow fluorescent dyes and proteins (e.g. YFP, mFruit series) simultaneously has been proven with a single IR laser wavelength. A new approach is to extend the usability of existing tunable Titanium sapphire lasers by adding a fixed IR wavelength with an Yb femtosecond oscillator. By that means a multitude of applications for multimodal imaging and optogenetics can be supported. Furthermore fs Yb-lasers are available with a repetition rate of typically 10 MHz and an average power of typically 5 W resulting in pulse energy of typically 500 nJ, which is comparably high for fs-oscillators. This makes them an ideal tool for two-photon spinning disk laser scanning microscopy and holographic patterning for simultaneous photoactivation of large cell populations. With this work we demonstrate that economical, small-footprint Yb fixed-wavelength lasers can present an interesting add-on to tunable lasers that are commonly used in multiphoton microscopy. The Yb fs-lasers hereby offer higher power for imaging of red fluorescent dyes and proteins, are ideally enhancing existing Ti:sapphire lasers with more power in the IR, and are supporting pulse energy and power hungry applications such as spinning disk microscopy and holographic patterning.

  18. Pulse width and energy influence on laser micromachining of metals in a range of 100 fs to 5 ps

    Energy Technology Data Exchange (ETDEWEB)

    Le Harzic, R. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany) and Laboratoire Traitement du Signal et Instrumentation (TSI), UMR CNRS 5516, Bat F, 10 rue Barrouin, 42000 Saint Etienne (France)]. E-mail: leharzic@jenlab.de; Breitling, D. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany); Weikert, M. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany); Sommer, S. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany); Foehl, C. [Forschungsgesellschaft fuer Strahlwerkzeuge mbH (FGSW), Nobelstrasse 15, 70569 Stuttgart (Germany); Valette, S. [Laboratoire Traitement du Signal et Instrumentation (TSI), UMR CNRS 5516, Bat F, 10 rue Barrouin, 42000 Saint Etienne (France); Donnet, C. [Laboratoire Traitement du Signal et Instrumentation (TSI), UMR CNRS 5516, Bat F, 10 rue Barrouin, 42000 Saint Etienne (France); Audouard, E. [Laboratoire Traitement du Signal et Instrumentation (TSI), UMR CNRS 5516, Bat F, 10 rue Barrouin, 42000 Saint Etienne (France); Dausinger, F. [Institut fuer Strahlwerkzeuge (IFSW), Universitaet Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart (Germany)

    2005-08-15

    Micromachining of steel, Cu and Al is studied. Ablation depths per pulse are deduced for laser pulse durations between 100 fs and 5 ps for fluences in the range of 150 mJ cm{sup -2} to 20 J cm{sup -2}. The evolution of ablation rates allows to evidence a low and a high fluence regime. Ablation thresholds and penetration depths are deduced as functions of pulse duration. While in the low fluence regime the penetration depth is close to the theoretical optical penetration depth, at higher fluences the effective heat penetration depth is 10-20 times bigger with also higher ablation thresholds. Even in the femtosecond range thermal ablation processes occur and reduce quality, accuracy and efficiency of micromachining. Additionally, the latter are influenced by strong beam distortions due to nonlinear interaction between the radiation and the atmospheric gas. In the case of steel and Cu, the pulse duration seems not to affect microprocessing, but it is demonstrated to play a role for Al for pulses between 1 and 5 ps.

  19. Ruby Emission in the Range 400-800 nm with Excitation by Continuous-Wave CO2 Laser Pulses

    Science.gov (United States)

    Marchenko, V. M.; Kiselev, V. V.

    2017-01-01

    Thermal emission spectra of ruby single crystals in the range 400-800 nm were studied experimentally as functions of the intensity at 10.6 μm of exciting pulses ( 0.5 s) from a continuous-wave electrical-discharge CO2 laser. Spectra at excitation intensity 1-20 kW/cm2 were superpositions of the thermal emission continuum of the sapphire crystal lattice in the range 600-800 nm and selective emission spectra of Cr3+ that were observed for the first time for ruby and consisted of R-lines at 695 nm; N-lines at 715 nm; 2 T 1, 4 T 2 → 4 A 2 transition bands at 672 and 643 nm; and 4 T 1, 2 T 2 → 4 A 2 transition bands at 530 and 490 nm that were not observed in the luminescence spectrum. Time dependences of the shapes of selective emission spectra, quenching and shifts of the R 1 line, and the temperature dependence of ruby luminescence spectra were investigated.

  20. Integration of a synthetic vision system with airborne laser range scanner-based terrain referenced navigation for precision approach guidance

    Science.gov (United States)

    Uijt de Haag, Maarten; Campbell, Jacob; van Graas, Frank

    2005-05-01

    Synthetic Vision Systems (SVS) provide pilots with a virtual visual depiction of the external environment. When using SVS for aircraft precision approach guidance systems accurate positioning relative to the runway with a high level of integrity is required. Precision approach guidance systems in use today require ground-based electronic navigation components with at least one installation at each airport, and in many cases multiple installations to service approaches to all qualifying runways. A terrain-referenced approach guidance system is envisioned to provide precision guidance to an aircraft without the use of ground-based electronic navigation components installed at the airport. This autonomy makes it a good candidate for integration with an SVS. At the Ohio University Avionics Engineering Center (AEC), work has been underway in the development of such a terrain referenced navigation system. When used in conjunction with an Inertial Measurement Unit (IMU) and a high accuracy/resolution terrain database, this terrain referenced navigation system can provide navigation and guidance information to the pilot on a SVS or conventional instruments. The terrain referenced navigation system, under development at AEC, operates on similar principles as other terrain navigation systems: a ground sensing sensor (in this case an airborne laser scanner) gathers range measurements to the terrain; this data is then matched in some fashion with an onboard terrain database to find the most likely position solution and used to update an inertial sensor-based navigator. AEC's system design differs from today's common terrain navigators in its use of a high resolution terrain database (~1 meter post spacing) in conjunction with an airborne laser scanner which is capable of providing tens of thousands independent terrain elevation measurements per second with centimeter-level accuracies. When combined with data from an inertial navigator the high resolution terrain database and

  1. Development of Two Color Fluorescent Imager and Integrated Fluidic System for Nanosatellite Biology Applications

    Science.gov (United States)

    Wu, Diana Terri; Ricco, Antonio Joseph; Lera, Matthew P.; Timucin, Linda R.; Parra, Macarena P.

    2012-01-01

    Nanosatellites offer frequent, low-cost space access as secondary payloads on launches of larger conventional satellites. We summarize the payload science and technology of the Microsatellite in-situ Space Technologies (MisST) nanosatellite for conducting automated biological experiments. The payload (two fused 10-cm cubes) includes 1) an integrated fluidics system that maintains organism viability and supports growth and 2) a fixed-focus imager with fluorescence and scattered-light imaging capabilities. The payload monitors temperature, pressure and relative humidity, and actively controls temperature. C. elegans (nematode, 50 m diameter x 1 mm long) was selected as a model organism due to previous space science experience, its completely sequenced genome, size, hardiness, and the variety of strains available. Three strains were chosen: two green GFP-tagged strains and one red tdTomato-tagged strain that label intestinal, nerve, and pharyngeal cells, respectively. The integrated fluidics system includes bioanalytical and reservoir modules. The former consists of four 150 L culture wells and a 4x5 mm imaging zone the latter includes two 8 mL fluid reservoirs for reagent and waste storage. The fluidic system is fabricated using multilayer polymer rapid prototyping: laser cutting, precision machining, die cutting, and pressure-sensitive adhesives it also includes eight solenoid-operated valves and one mini peristaltic pump. Young larval-state (L2) nematodes are loaded in C. elegans Maintenance Media (CeMM) in the bioanalytical module during pre-launch assembly. By the time orbit is established, the worms have grown to sufficient density to be imaged and are fed fresh CeMM. The strains are pumped sequentially into the imaging area, imaged, then pumped into waste. Reagent storage utilizes polymer bags under slight pressure to prevent bubble formation in wells or channels. The optical system images green and red fluorescence bands by excitation with blue (473 nm peak

  2. Electronic sideband locking of 318.6nm UV laser to an ultrastable optical cavity with a wide continuously tunable range

    CERN Document Server

    Bai, Jiandong; He, Jun; Wang, Junmin

    2016-01-01

    We have demonstrated a frequency-stabilized tunable 318.6 nm ultraviolet (UV) laser system for the single-photon 6S1/2 - nP (n = 70 ~ 100) Rydberg excitation of cesium atoms. The 637.2 nm laser produced by single-pass sum frequency generation from two infrared fiber lasers is offset locked to a high-finesse ultra-low expansion (ULE) optical cavity placed in ultra-high vacuum using the electronic sideband locking technique. The generated 318.6 nm UV laser via cavity-enhanced second-harmonic generation can be continuously tuned over 4 GHz by indirectly changing modulation frequency on the electro-optic phase modulator while the whole laser system remains locked. We analyze the tuning range mainly depends on the modulator bandwidth and the tunable range of the seed laser. The locking scheme offers a method to compensate the frequency difference between the reference frequency and the goal frequency to a desired excited state, and has huge potential in precision spectroscopic experiments of cold atoms.

  3. Enlarging the linear response range of velocity with optimum imaging parameters and modified data processing in laser speckle imaging

    Science.gov (United States)

    Qiu, Jianjun; Li, Pengcheng; Ul'yanov, Sergey S.; Zeng, Shaoqun; Luo, Qingming

    2008-02-01

    Laser speckle imaging (LSI) technique is considered as a promising method of accessing cerebral blood flow (CBF) of animals for its high spatiotemporal resolution and simplicity. It is important in LSI that optimum imaging parameters and limited noises should be confirmed to promote the imaging precision. We investigated in this paper different factors which may affect the imaging results with a moving white plate model, and then proposed a method of enlarging the linear response range of velocity. Through experiment, we proposed in our LSI system the optimum imaging parameters, including the numerical aperture and magnification of microscopy, the integration time, the gain mode of CCD camera. The average intensity was found optimum at about 800 counts out of 4096 grey level, which permits the highest contrast in our experiment. To eliminate the influence of uneven illumination, a direct current weight of 27 counts was subtracted during data processing. The result indicated that the relationship between measured velocity and the real one remained linear with R2 equaling to 0.99 throughout the scale of 80 mm/s.

  4. Low-cost vehicle-mounted enhanced vision system comprised of a laser illuminator and range-gated camera

    Science.gov (United States)

    Pencikowski, Paul S.

    1996-05-01

    Considerable research has been done regarding the use of enhanced vision as a means to enable a vehicle operator to `see' through bad weather or obscuration such as smoke and dust. This research has generally emphasized Forward-looking infra-red (Flir) and millimeter-wave (radar) technologies. Flir is an acceptable approach if modest performance is all that is required. Millimeter wave radar has distinct advantages over Flir in certain cases, but generally requires operator training to interpret various display-screen presentations. The Northrop Grumman Corporation has begun a major sensor-development program to develop a prototype (eye-safe) laser-illuminator/range-gated camera system. The near-term goal is to field a system that would deliver a minimum of 3000 foot penetration of worst-case fog/obscurant. This image would appear on a display as a high resolution monochromatic image. This paper will explore the concept, the proposed automotive application, and the projected cost.

  5. Phantom-based comparison of the accuracy of point clouds extracted from stereo cameras and laser range scanner

    Science.gov (United States)

    Kumar, Ankur N.; Pheiffer, Thomas S.; Simpson, Amber L.; Thompson, Reid C.; Miga, Michael I.; Dawant, Benoit M.

    2013-03-01

    Using computational models, images acquired pre-operatively can be updated to account for intraoperative brain shift in image-guided surgical (IGS) systems. An optically tracked textured laser range scanner (tLRS) furnishes the 3D coordinates of cortical surface points (3D point clouds) over the surgical field of view and provides a correspondence between these and the pre-operative MR image. However, integration of the acquired tLRS data into a clinically acceptable system compatible throughout the clinical workflow of tumor resection has been challenging. This is because acquiring the tLRS data requires moving the scanner in and out of the surgical field, thus limiting the number of acquisitions. Large differences between acquisitions caused by tumor resection and tissue manipulation make it difficult to establish correspondence and estimate brain motion. An alternative to the tLRS is to use temporally dense feature-rich stereo surgical video data provided by the operating microscope. This allows for quick digitization of the cortical surface in 3D and can help continuously update the IGS system. In order to understand the tradeoffs between these approaches as input to an IGS system, we compare the accuracy of the 3D point clouds extracted from the stereo video system of the surgical microscope and the tLRS for phantom objects in this paper. We show that the stereovision system of the surgical microscope achieves accuracy in the 0.46-1.5mm range on our phantom objects and is a viable alternative to the tLRS for neurosurgical applications.

  6. A simplified method for identification of the vibrational series of long-range states in Na{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Vivanco, F.J.; Paiva, R.R. de; Pedrozo-Peñafiel, E.; Farias, K.M.; Bagnato, V.S., E-mail: franklinze@gmail.com [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Fisica

    2015-06-15

    We performed two-color photoassociative ionization experiments in cold sodium atoms in a dark MOT. We produce a sample where most of the atoms were in the ground hyperfine state F=1. Applying a laser with variable frequency, in the region of 0 to - 32 GHz, we obtained a photoassociative spectra containing sequences of different long-range potentials. Using the scaling law for intermediate states, we identified the vibrational series of involved states, separating the sequences. In this way, we have identified the vibrational series for the 1{sub g}, 0{sup +}{sub u}, and 0{sup -}{sub g} states contributions. (author)

  7. Two-color light-emitting diodes with polarization-sensitive high extraction efficiency based on graphene

    Science.gov (United States)

    H, Sattarian; S, Shojaei; E, Darabi

    2016-05-01

    In the present study, graphene photonic crystals are employed to enhance the light extraction efficiency (LEE) of two-color, red and blue, light-emitting diode (LED). The transmission characteristics of one-dimensional (1D) Fibonacci graphene photonic crystal LED (FGPC-LED) are investigated by using the transfer matrix method and the scaling study is presented. We analyzed the influence of period, thickness, and permittivity in the structure to enhance the LEE. The transmission spectrum of 1D FGPC has been optimized in detail. In addition, the effects of the angle of incidence and the state of polarization are investigated. As the main result, we found the optimum values of relevant parameters to enhance the extraction of red and blue light from an LED as well as provide perfect omnidirectional and high peak transmission filters for the TE and TM modes.

  8. Flow cytometric quantification of all phases of the cell cycle and apoptosis in a two-color fluorescence plot.

    Directory of Open Access Journals (Sweden)

    Christine Vignon

    Full Text Available An optimal technology for cell cycle analysis would allow the concomitant measurement of apoptosis, G0, G1, S, G2 and M phases in combination with cell surface phenotyping. We have developed an easy method in flow cytometry allowing this discrimination in an only two-color fluorescent plot. It is based on the concomitant use of 7-amino-actinomycin D and the antibodies anti-Ki67 and anti-phospho(Ser10-histone H3, both conjugated to Alexa Fluor®488 to discriminate G0 and M phases, respectively. The method is particularly valuable in a clinical setting as verified in our laboratory by analyzing human leukemic cells from marrow samples or after exposure to cell cycle modifiers.

  9. Computer Control of the Spectral Composition of the Powerful Laser System Irradiation with a Wide Range of Laser Transitions on Metal Vapors

    Directory of Open Access Journals (Sweden)

    Soldatov Anatoly

    2016-01-01

    Full Text Available The results of the experimental study cycle of the multiwave metal vapor laser system on the basis of the original configuration of the multimedia laser emitter. The spectral parameters of the setup have been controlled using a personal computer (PC. This allows carrying out their independent optimization according to excitation conditions, and, therefore, promptly allocating the output set of oscillating wavelengths and their relative distribution in power, which makes the system attractive for scientific and technological application.

  10. Range imaging pulsed laser sensor with two-dimensional scanning of transmitted beam and scanless receiver using high-aspect avalanche photodiode array for eye-safe wavelength

    Science.gov (United States)

    Tsuji, Hidenobu; Imaki, Masaharu; Kotake, Nobuki; Hirai, Akihito; Nakaji, Masaharu; Kameyama, Shumpei

    2017-03-01

    We demonstrate a range imaging pulsed laser sensor with two-dimensional scanning of a transmitted beam and a scanless receiver using a high-aspect avalanche photodiode (APD) array for the eye-safe wavelength. The system achieves a high frame rate and long-range imaging with a relatively simple sensor configuration. We developed a high-aspect APD array for the wavelength of 1.5 μm, a receiver integrated circuit, and a range and intensity detector. By combining these devices, we realized 160×120 pixels range imaging with a frame rate of 8 Hz at a distance of about 50 m.

  11. 2.3 µm range InP-based type-II quantum well Fabry-Perot lasers heterogeneously integrated on a silicon photonic integrated circuit.

    Science.gov (United States)

    Wang, Ruijun; Sprengel, Stephan; Boehm, Gerhard; Muneeb, Muhammad; Baets, Roel; Amann, Markus-Christian; Roelkens, Gunther

    2016-09-01

    Heterogeneously integrated InP-based type-II quantum well Fabry-Perot lasers on a silicon waveguide circuit emitting in the 2.3 µm wavelength range are demonstrated. The devices consist of a "W"-shaped InGaAs/GaAsSb multi-quantum-well gain section, III-V/silicon spot size converters and two silicon Bragg grating reflectors to form the laser cavity. In continuous-wave (CW) operation, we obtain a threshold current density of 2.7 kA/cm2 and output power of 1.3 mW at 5 °C for 2.35 μm lasers. The lasers emit over 3.7 mW of peak power with a threshold current density of 1.6 kA/cm2 in pulsed regime at room temperature. This demonstration of heterogeneously integrated lasers indicates that the material system and heterogeneous integration method are promising to realize fully integrated III-V/silicon photonics spectroscopic sensors in the 2 µm wavelength range.

  12. Pulse laser photolysis of aqueous ozone in the microsecond range studied by time-resolved far-ultraviolet absorption spectroscopy.

    Science.gov (United States)

    Goto, Takeyoshi; Morisawa, Yusuke; Higashi, Noboru; Ikehata, Akifumi; Ozaki, Yukihiro

    2013-05-01

    Chemical dynamics of an ozone (O3) pulse-photolytic reaction in aqueous solutions were studied with pump-probe transient far-ultraviolet (FUV) absorption spectroscopy. With a nanosecond pulse laser of 266 nm as pump light, transient spectra of O3 aqueous solutions (78-480 μM, pH 2.5-11.3) were acquired in the time range from -50 to 50 μs in the wavelength region from 190 to 225 nm. The measured transient spectra were linearly decomposed into the molar absorption coefficients and the concentration-time profiles of constituted chemical components with a multivariate curve resolution method. From the dependences of the time-averaged concentrations for 20 μs of the constituted chemicals on the initial concentration of O3, it was found that the transient spectra involve the decomposition of O3 and the formation of hydrogen peroxide (H2O2) and a third component that is assigned to hydroxyl radical (OH) or perhydroxyl radical (HO2). Furthermore, the pH dependence of the time-averaged concentration of the third components indicates that HO2 is more probable than OH as the third component. The time-averaged concentration ratio of each chemical component to the initial O3 concentration depends on the pH conditions from -0.95 to -0.60 for O3, 0.98 to 1.2 for H2O2, 0.002 to 0.29 for OH, and 0.012 to 0.069 for HO2.

  13. High precision gravity analysis and hydrological modeling from the Lunar Laser Ranging Observatory at Apache Point, New Mexico

    Science.gov (United States)

    Liang, Jiahao

    The NASA-supported Lunar Laser Ranging project (LLR) is located at Apache Point, New Mexico, which strives to precisely measure the orbital distance between the Earth and the Moon in an accuracy of a few millimeters. To archive this objective, LLR project requires precise data on local ground deformation, which is difficult to measure directly. However, the high precision gravity data is the reflection of vertical ground deformation of the Earth, therefore the gravity data is able to contribute to the LLR project. Gravity time series is affected by Earth tides, atmospheric pressure, polar motion, and the most critical effect, local hydrology. In order to isolate pure geodetic variation, these effects must be removed from the data. Thus, the goal of this research is to create models of above effects, especially local hydrology model, in order to isolate the vertical deformation signal. The Earth tides, atmospheric pressure and polar motion effects have been modeled and subtracted from gravity data (2009~2012). The local hydrological model has been created based on the in-situ data, which are rainfall, snowfall and temperature. The correlation coefficient and RMS misfit between the hydrological model and gravity residual (2010~2012) is 0.92 and 1.26 microGal. The instrument drift corrections in 2009 have been reanalyzed after comparing with some global hydrological models. The gravity residual from new corrections showed a correlation coefficient of 0.76 and RMS misfit of 1.25 microGal. The isolated deformation signal was obtained after we subtracted the hydrological effects, and the results can be used for further modeling.

  14. Multi-sensors multi-baseline mapping system for mobile robot using stereovision camera and laser-range device

    Directory of Open Access Journals (Sweden)

    Mohammed Faisal

    2016-06-01

    Full Text Available Countless applications today are using mobile robots, including autonomous navigation, security patrolling, housework, search-and-rescue operations, material handling, manufacturing, and automated transportation systems. Regardless of the application, a mobile robot must use a robust autonomous navigation system. Autonomous navigation remains one of the primary challenges in the mobile-robot industry; many control algorithms and techniques have been recently developed that aim to overcome this challenge. Among autonomous navigation methods, vision-based systems have been growing in recent years due to rapid gains in computational power and the reliability of visual sensors. The primary focus of research into vision-based navigation is to allow a mobile robot to navigate in an unstructured environment without collision. In recent years, several researchers have looked at methods for setting up autonomous mobile robots for navigational tasks. Among these methods, stereovision-based navigation is a promising approach for reliable and efficient navigation. In this article, we create and develop a novel mapping system for a robust autonomous navigation system. The main contribution of this article is the fuse of the multi-baseline stereovision (narrow and wide baselines and laser-range reading data to enhance the accuracy of the point cloud, to reduce the ambiguity of correspondence matching, and to extend the field of view of the proposed mapping system to 180°. Another contribution is the pruning the region of interest of the three-dimensional point clouds to reduce the computational burden involved in the stereo process. Therefore, we called the proposed system multi-sensors multi-baseline mapping system. The experimental results illustrate the robustness and accuracy of the proposed system.

  15. Two Color Entanglement

    CERN Document Server

    Samblowski, Aiko; Grosse, Nicolai; Lam, Ping Koy; Schnabel, Roman

    2010-01-01

    We report on the generation of entangled states of light between the wavelengths 810 and 1550 nm in the continuous variable regime. The fields were produced by type I optical parametric oscillation in a standing-wave cavity build around a periodically poled potassium titanyl phosphate crystal, operated above threshold. Balanced homodyne detection was used to detect the non-classical noise properties, while filter cavities provided the local oscillators by separating carrier fields from the entangled sidebands. We were able to obtain an inseparability of I=0.82, corresponding to about -0.86 dB of non-classical quadrature correlation.

  16. Single-shot high-dynamic range laser pulse contrast measurement using Fourth-Order-Crosscorrelation via Self-Referenced-Spectral-Interferometry (FOX-SRSI)

    CERN Document Server

    Palaniyappan, Sasi; Shimada, T; Shah, R C; Jung, D; Gautier, D C; Hegelich, B M; Fernandez, J C

    2012-01-01

    High-dynamic range isolation of the interference term and the non-interference term in the inverse Fourier-transformed spectral interferogram as required in Self-Referenced-Spectral-Interferometry (SRSI) for single-shot high-dynamic range laser pulse characterization is not always practically possible due to presence of the non-interference term over the entire temporal widow. Alternatively, we propose and demonstrate that one could directly obtain the single-shot Fourth-Order-Crosscorrelation (FOX) of the laser pulse to be characterized via SRSI (FOX-SRSI) from the interference term as the high-dynamic range laser contrast measurement, avoiding the need to isolate the interference and non-interference terms. As a consequence, the undesired contribution from the non-interference term limits the valid temporal window of the measurement. The single-shot FOX-SRSI result is consistent with the laser contrast measured independently using a multi-shot scanning third-order autocorrelator.

  17. Kinetics of gas phase OH radical reaction with thiophene in the 272-353 K temperature range: A laser induced fluorescence study

    Science.gov (United States)

    Kawade, Monali N.; Srinivas, D.; Upadhyaya, Hari P.

    2017-08-01

    Absolute rate coefficient for the gas phase reaction of OH radical with thiophene has been measured using the laser photolysis (LP) - laser induced fluorescence (LIF) technique. The kinetics measurements were done over the temperature range of 272-353 K and pressure range of 20-30 Torr. The bimolecular rate coefficients obtained were pressure independent in the above pressure range and showed Arrhenius type behaviour which were fitted to the expression k(T) = (4.53 ± 0.55) × 10-12 exp[(250 ± 30)/T] cm3 molecule-1 s-1. The reaction shows weak negative temperature dependence. These results were discussed with available literature and the tropospheric lifetime of thiophene was calculated.

  18. Absolute absorption and fluorescence measurements over a dynamic range of 10$^6$ with cavity-enhanced laser-induced fluorescence

    CERN Document Server

    Sanders, Scott E; Nahler, N Hendrik; Wrede, Eckart

    2013-01-01

    We describe a novel experimental setup that combines the advantages of both laser-induced fluorescence and cavity ring-down techniques. The simultaneous measurement of the ring-down and fluorescence signals from the same sample in a single laser beam delivers the calibration of the fluorescence measurement to gain absolute quantities: absorption cross section, sample density and fluorescence quantum yield. At the same time, the fluorescence measurement extends the dynamic range of a stand-alone cavity ring-down setup from typically three to at least six orders of magnitude. The methodology of this combined cavity-enhanced laser-induced fluorescence (CELIF) technique is developed and rigorously tested against the spectroscopy of 1,4-bis(phenylethynyl)benzene in a molecular beam and density measurements in a cell.

  19. [Effects of low power laser radiation of blue, green and red ranges on free radical processes in rat blood in endotoxic shock].

    Science.gov (United States)

    Machneva, T V; Kosmacheva, N V; Vladimirov, Iu A; Osipov, A N

    2013-01-01

    This study was performed to investigate the effects of low power laser radiation in blue (441.2 nm), green (532.5 nm) and red (632.8 nm) wavelength ranges on free radical processes in experimental endotoxic shock in rats. The experimental model was produced by intraperitoneal injection of lipopolysacharide B (25 mg/kg) (LPS). The following parameters were assayed in the study: the chemiluminescent assay (to evaluate the free radical production by blood leukocytes), nitro blue tetrazolium assay (to monitor the superoxide dismutase activity of plasma) and cis-parinaric acid fluorescence (to estimate the intensity of lipid peroxidation in erythrocyte membranes). It was found that the low power laser radiation significantly influenced all investigated processes, in animals both treated and untreated without LPS injection. The most pronounced effects were observed in all groups of animals subjected to the low power laser radiation: at the dose of 0.75 J/cm2 green laser was most effective and at the dose of 1.5 J/cm2 green and red lasers provided maximal effects. The mechanisms of the observed phenomena are discussed.

  20. Validity of Dynamic Light Scattering Method to Analyze a Range of Gold and Copper Nanoparticle Sizes Attained by Solids Laser Ablation in Liquid

    Directory of Open Access Journals (Sweden)

    Yu. V. Golubenko

    2014-01-01

    Full Text Available Nanoparticles of metals possess a whole series of features, concerned with it’s sizes, this leads to appearing or unusual electromagnetic and optical properties, which are untypical for particulates.An extended method of receiving nanoparticles by means of laser radiation is pulse laser ablation of hard targets in liquid medium.Varying the parameters of laser radiation, such as wavelength of laser radiation, energy density, etc., we can operate the size and shape of the resultant particles.The greatest trend of application in medicine have the nanoparticles of iron, copper, silver, silicon, magnesium, gold and zinc.The subject matter in this work is nanoparticles of copper and gold, received by means of laser ablation of hard targets in liquid medium.The aim of exploration, represented in the article, is the estimation of application of the dynamic light scattering method for determination of the range of nanoparticles sizes in the colloidal solution.For studying of the laser ablation process was chosen the second harmonic of Nd:YAG laser with the wavelength of 532 nm. Special attention was spared for the description of the experiment technique of receiving of nanoparticles.As the liquid medium ethanol and distillation water were used.For exploration of the received colloidal system have been used the next methods: DLS, transmission electron microscopy (TEM and scanning electron microscopy (SEM.The results of measuring by DLS method showed that colloidal solution of the copper in the ethanol is the steady system. Copper nanoparticle’s size reaches 200 nm and is staying in the same size for some time.Received system from the gold’s nanoparticles is polydisperse, unsteady and has a big range of the nanoparticle’s sizes. This fact was confirmed by means of photos, got from the TEM FEI Tecnai G2F20 + GIF and SEM Helios NanoLab 660. The range of the gold nanoparticle’s sizes is from 5 to 60 nm. So, it has been proved that the DLS method is

  1. Stimulated Emission Pumping by Two-Color Resonant Four-Wave Mixing: Rotational Characterization of Vibrationally Excited HCO

    Energy Technology Data Exchange (ETDEWEB)

    Radi, P.P.; Tulej, M.; Knopp, G.; Beaud, P.; Gerber, T.

    2004-03-01

    Stimulated emission pumping by applying two-color resonant four-wave mixing is used to measure rotationally resolved spectra of the HCO (0,0,0) B {sup 2}A' - (0,3,1) X {sup 2}A' transition. The formyl radical is produced by photodissociation of formaldehyde at 31710.8 cm{sup -1} under thermalized conditions in a low pressure cell. In contrast to the highly congested one-color spectrum of HCO at room temperature, the doubleresonance method yields well isolated transitions which are assigned unambiguously due to intermediate level labeling. 89 rotational transitions have been assigned and yield accurate rotational constants for the vibrationally excited (0,3,1) band of the electronic ground state X {sup 2}A' of HCO. The determined rotational constant A = 25.84{+-}0.01 cm-1 is considerably higher than that for the vibrationless ground state and reflects the structural change due to excitation of the bending mode of the formyl radical. (author)

  2. Two-color widefield fluorescence microendoscopy enables multiplexed molecular imaging in the alveolar space of human lung tissue

    Science.gov (United States)

    Krstajić, Nikola; Akram, Ahsan R.; Choudhary, Tushar R.; McDonald, Neil; Tanner, Michael G.; Pedretti, Ettore; Dalgarno, Paul A.; Scholefield, Emma; Girkin, John M.; Moore, Anne; Bradley, Mark; Dhaliwal, Kevin

    2016-04-01

    We demonstrate a fast two-color widefield fluorescence microendoscopy system capable of simultaneously detecting several disease targets in intact human ex vivo lung tissue. We characterize the system for light throughput from the excitation light emitting diodes, fluorescence collection efficiency, and chromatic focal shifts. We demonstrate the effectiveness of the instrument by imaging bacteria (Pseudomonas aeruginosa) in ex vivo human lung tissue. We describe a mechanism of bacterial detection through the fiber bundle that uses blinking effects of bacteria as they move in front of the fiber core providing detection of objects smaller than the fiber core and cladding (˜3 μm). This effectively increases the measured spatial resolution of 4 μm. We show simultaneous imaging of neutrophils, monocytes, and fungus (Aspergillus fumigatus) in ex vivo human lung tissue. The instrument has 10 nM and 50 nM sensitivity for fluorescein and Cy5 solutions, respectively. Lung tissue autofluorescence remains visible at up to 200 fps camera acquisition rate. The optical system lends itself to clinical translation due to high-fluorescence sensitivity, simplicity, and the ability to multiplex several pathological molecular imaging targets simultaneously.

  3. Two-color vibrational, femtosecond, fully resonant electronically enhanced CARS (FREE-CARS) of gas-phase nitric oxide

    Science.gov (United States)

    Stauffer, Hans U.; Roy, Sukesh; Schmidt, Jacob B.; Wrzesinski, Paul J.; Gord, James R.

    2016-09-01

    A resonantly enhanced, two-color, femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) approach is demonstrated and used to explore the nature of the frequency- and time-dependent signals produced by gas-phase nitric oxide (NO). Through careful selection of the input pulse wavelengths, this fully resonant electronically enhanced CARS (FREE-CARS) scheme allows rovibronic-state-resolved observation of time-dependent rovibrational wavepackets propagating on the vibrationally excited ground-state potential energy surface of this diatomic species. Despite the use of broadband, ultrafast time-resolved input pulses, high spectral resolution of gas-phase rovibronic transitions is observed in the FREE-CARS signal, dictated by the electronic dephasing timescales of these states. Analysis and computational simulation of the time-dependent spectra observed as a function of pump-Stokes and Stokes-probe delays provide insight into the rotationally resolved wavepacket motion observed on the excited-state and vibrationally excited ground-state potential energy surfaces of NO, respectively.

  4. Determination of self generated magnetic field and the plasma density using Cotton Mouton polarimetry with two color probes

    Directory of Open Access Journals (Sweden)

    Joshi A.S.

    2013-11-01

    Full Text Available Self generated magnetic fields (SGMF in laser produced plasmas are conventionally determined by measuring the Faraday rotation angle of a linearly polarized laser probe beam passing through the plasma along with the interferogram for obtaining plasma density. In this paper, we propose a new method to obtain the plasma density and the SGMF distribution from two simultaneous measurements of Cotton Mouton polarimetry of two linearly polarized probe beams of different colors that pass through plasma in a direction normal to the planar target. It is shown that this technique allows us to determine the distribution of SGMF and the plasma density without doing interferometry of laser produced plasmas.

  5. Development of a Compton Camera for Online Range Monitoring of Laser-Accelerated Proton Beams via Prompt-Gamma Detection

    NARCIS (Netherlands)

    Thirolf, P.G.; Lang, C.; Aldawood, S.; Van der Kolff, H.G.; Maier, L.; Schaart, D.R.; Parodi, K.

    2014-01-01

    Presently large efforts are conducted in Munich towards the development of proton beams for bio-medical applications, generated via the technique of particle acceleration from high-power, short-pulse lasers. While so far mostly offline diagnostics tools are used in this context, we aim at developing

  6. A Study of the Radiant Ignition of a Range of Pyrotechnic Materials Using a CO2 Laser

    Science.gov (United States)

    1990-08-01

    tracers. Journal of Ballistics, 3 (4), 627. 10. Gebhard, T. (1988). Naval Ordnance Station, Indian Head, USA, private communicatin . 11. Culling, M.P...a C02 laser AUTHOR(S) CORPORATE AUTHOR DSTO Materials Research Laboratory L de Yong, B. Park and F. Valenta PO Box 50 Ascot Vale Victoria 3032 REPORT

  7. Measurement of angularly dependent spectra of betatron gamma-rays from a laser plasma accelerator with quadrant-sectored range filters

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Jong Ho, E-mail: jhjeon07@ibs.re.kr; Nakajima, Kazuhisa, E-mail: naka115@dia-net.ne.jp; Rhee, Yong Joo; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Shin, Jung Hun; Yoo, Byung Ju; Jo, Sung Ha; Shin, Kang Woo [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005 (Korea, Republic of); Kim, Hyung Taek; Sung, Jae Hee; Lee, Seong Ku; Choi, Il Woo [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005 (Korea, Republic of); Advanced Photonics Research Institute, GIST, Gwangju 61005 (Korea, Republic of); Hojbota, Calin; Bae, Lee Jin; Jung, Jaehyung; Cho, Min Sang; Cho, Byoung Ick; Nam, Chang Hee [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005 (Korea, Republic of); Department of Physics and Photon Science, GIST, Gwangju 61005 (Korea, Republic of)

    2016-07-15

    Measurement of angularly dependent spectra of betatron gamma-rays radiated by GeV electron beams from laser wakefield accelerators (LWFAs) are presented. The angle-resolved spectrum of betatron radiation was deconvolved from the position dependent data measured for a single laser shot with a broadband gamma-ray spectrometer comprising four-quadrant sectored range filters and an unfolding algorithm, based on the Monte Carlo code GEANT4. The unfolded gamma-ray spectra in the photon energy range of 0.1–10 MeV revealed an approximately isotropic angular dependence of the peak photon energy and photon energy-integrated fluence. As expected by the analysis of betatron radiation from LWFAs, the results indicate that unpolarized gamma-rays are emitted by electrons undergoing betatron motion in isotropically distributed orbit planes.

  8. Investigation of the spectral characteristics of a pulsed F/sub 2/-center laser tunable in the range 1. 1--1. 26. mu

    Energy Technology Data Exchange (ETDEWEB)

    Gusev, Y.L.; Kirpichnikov, A.V.; Marennikov, S.I.

    1979-12-01

    A description is given of a simple resonator system in which single-frequency stimulated emission was achieved from a pulsed F-center laser. The average line width due to fluctuations of the lasing frequency was 0.01 cm/sup -1/ in the 1.1--1.26 ..mu.. spectral range. Investigations were made of the reasons for these fluctuations and numerical estimates were made of the different factors responsible for these fluctuations.

  9. Spectral emission properties of a laser-produced plasma light source in the sub-200 nm range for wafer inspection applications

    Science.gov (United States)

    Gambino, Nadia; Rollinger, Bob; Hudgins, Duane; Abhari, Reza S.

    2015-07-01

    The spectral emission properties of a droplet-based laser-produced plasma are investigated in the vacuum ultraviolet (VUV) range. Measurements are performed with a spectrograph that operates from 30 to 180 nm with a spectral resolution of 0.1 nm. The emission spectra are recorded for different metal droplet targets, namely tin, indium, and gallium. Measurements were performed at different pressure levels of the background gas. Several characteristic emission lines are observed. The spectra are also calibrated in intensity in terms of spectral radiance to allow absolute emission power estimations from the light source in the VUV region. The presented experimental results are relevant for alternative light sources that would be needed for future wafer inspection tools. In addition, the experimental results help to determine the out-of-band radiation emission of a tin-based extreme ultraviolet (EUV) source. By tuning the type of fuel, the laser energies, and the background gas, the laser-produced plasma light source shows good capabilities to be operated as a light source that covers a spectral emission range from the EUV to the sub-200 nm range.

  10. Characterization of the 1 ^5Πu - 1 ^5Πg Band of C_2 by Two-Color Resonant Four-Wave Mixing and Lif

    Science.gov (United States)

    Radi, Peter

    2015-06-01

    The application of two-color resonant four-wave mixing (TC-RFWM) in combination with a discharge slit-source in a molecular beam environment is advantageous for the study of perturbations in C_2. Initial investigations have shown the potential of the method by a detailed deperturbation of the d3Π_g, v=4 state. The deperturbation of the d3Π_g, v=6 state unveiled the presence of the energetically lowest high-spin state of C_2. This dark state gains transition strength through the perturbation process with the d3Π_g, v=6 state yielding weak spectral features that are observable by the high sensitivity of the TC-RFWM technique. The successful deperturbation study of the d3Π_g, v=6 state resulted in the spectroscopic characterization of the quintet (15Πg) and an additional triplet state (d3Π_g, v=19). More recently, investigations have been performed by applying unfolded TC-RFWM to obtain further information on the quintet manifold. The first high-spin transition (15Πu) - 15Πg)) has been observed via an intermediate ``gateway'' state exhibiting both substantial triplet and quintet character owing to the perturbation between the 15Πg), v=0 and the d3Π_g, v=6 states. The high-lying quintet state is found to be predissociative and displays a shallow potential that accommodates three vibrational levels only. Further studies of the high-spin system will be presented in this contribution. By applying TC-RFWM and laser-induced fluorescence, data on the vibrational structure of the 15Πu - 15Πg system is obtained. The results are combined with high-level ab initio computations at the multi-reference configuration interaction (MRCI) level of theory and the largest possible basis currently implemented in the 2012 version of MOLPRO. P. Bornhauser, G. Knopp, T. Gerber, and P.P. Radi, Journal of Molecular Spectroscopy 262, 69 (2010) P. Bornhauser, Y. Sych, G. Knopp, T. Gerber, and P.P. Radi, Journal of Chemical Physics 134, 044302 (2011) Bornhauser, P., Marquardt, R

  11. [Lasers].

    Science.gov (United States)

    Passeron, T

    2012-11-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  12. Lasers.

    Science.gov (United States)

    Passeron, T

    2012-12-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  13. Two-color two-photon excited fluorescence of indole: Determination of wavelength-dependent molecular parameters

    Energy Technology Data Exchange (ETDEWEB)

    Herbrich, Sebastian; Al-Hadhuri, Tawfik; Gericke, Karl-Heinz, E-mail: k.Gericke@tu-bs.de [Institut für Physikalische und Theoretische Chemie, TU Braunschweig, Hans-Sommer-Straße 10, 38106 Braunschweig (Germany); Shternin, Peter S., E-mail: pshternin@gmail.com; Vasyutinskii, Oleg S., E-mail: osv@pms.ioffe.ru [Ioffe Institute, Politekhnicheskaya 26, 194021 St. Petersburg (Russian Federation); St. Petersburg Polytechnic University, Politekhnicheskaya 29, St. Petersburg 195251 (Russian Federation); Smolin, Andrey G. [Ioffe Institute, Politekhnicheskaya 26, 194021 St. Petersburg (Russian Federation)

    2015-01-14

    We present a detailed study of two-color two-photon excited fluorescence in indole dissolved in propylene glycol. Femtosecond excitation pulses at effective wavelengths from 268 to 293.33 nm were used to populate the two lowest indole excited states {sup 1}L{sub a} and {sup 1}L{sub b} and polarized fluorescence was then detected. All seven molecular parameters and the two-photon polarization ratio Ω containing information on two-photon absorption dynamics, molecular lifetime τ{sub f}, and rotation correlation time τ{sub rot} have been determined from experiment and analyzed as a function of the excitation wavelength. The analysis of the experimental data has shown that {sup 1}L{sub b}–{sup 1}L{sub a} inversion occurred under the conditions of our experiment. The two-photon absorption predominantly populated the {sup 1}L{sub a} state at all excitation wavelengths but in the 287–289 nm area which contained an absorption hump of the {sup 1}L{sub b} state 0-0 origin. The components of the two-photon excitation tensor S were analyzed giving important information on the principal tensor axes and absorption symmetry. The results obtained are in a good agreement with the results reported by other groups. The lifetime τ{sub f} and the rotation correlation time τ{sub rot} showed no explicit dependence on the effective excitation wavelength. Their calculated weighted average values were found to be τ{sub f} = 3.83 ± 0.14 ns and τ{sub rot} = 0.74 ± 0.06 ns.

  14. A CW calibrated laser pulse energy meter for the range 1 pJ to 100 mJ

    Science.gov (United States)

    White, M. G.; Leonhardt, R.; Livigni, D.; Lehman, J. H.

    2014-06-01

    We describe the use of a silicon photodiode trap detector and digital storage oscilloscope as an absolute laser pulse energy meter, capable of repetition rates of 85 Hz and 5% uncertainty (k = 2). The maximum repetition rate is limited by the decay time of the output pulse of the detector. The technique relies on a straightforward oscilloscope-based integration of the voltage pulse generated by the photodiode trap detector. We highlight the versatility of the technique by comparing it at 1064 nm with our high and low-level calorimeter based pulse energy scales, to which our calibration services are traceable. The good agreement of the results, along with comprehensive uncertainty analysis, validates the approach we have taken. We have demonstrated a basis for establishing laser pulse energy measurement using continuous wave (CW) sources and standard detectors.

  15. Multi-Range Conditional Random Field for Classifying Railway Electrification System Objects Using Mobile Laser Scanning Data

    OpenAIRE

    Jaewook Jung; Leihan Chen; Gunho Sohn; Chao Luo; Jong-Un Won

    2016-01-01

    Railways have been used as one of the most crucial means of transportation in public mobility and economic development. For safe railway operation, the electrification system in the railway infrastructure, which supplies electric power to trains, is an essential facility for stable train operation. Due to its important role, the electrification system needs to be rigorously and regularly inspected and managed. This paper presents a supervised learning method to classify Mobile Laser Scanning ...

  16. The 2 1Ag state of isolated cis-trans-1,3,5,7-octatetraene: two-color resonance enhanced two-photon ionization studies

    NARCIS (Netherlands)

    B.E. Kohler; T. Shaler; W.J. Buma

    1992-01-01

    Vibrationally resolved 1 1Ag2 1Ag excitation spectra and decay times for cis,trans-1,3,5,7-octatetraene seeded in a supersonic He expansion have been measured by two-color resonance enhanced two-photon ionization spectroscopy. The excitation energy of the 1 1Ag2 1Ag 0-0 band (29 035 cm-1 ) is ~6500

  17. mJ range all-fiber MOPA prototype with hollow-core fiber beam delivery designed for large scale laser facilities seeding (Conference Presentation)

    Science.gov (United States)

    Scol, Florent; Gouriou, Pierre; Perrin, Arnaud; Gleyze, Jean-François; Valentin, Constance; Bouwmans, Géraud; Hugonnot, Emmanuel

    2017-03-01

    The Laser megajoule (LMJ) is a French large scale laser facility dedicated to inertial fusion research. Its front-ends are based on fiber laser technology and generate highly controlled beams in the nanojoule range. Scaling the energy of those fiber seeders to the millijoule range is a way explored to upgrade LMJ's architecture. We report on a fully integrated narrow line-width all-fiber MOPA prototype at 1053 nm designed to meet stringent requirements of large-scale laser facilities seeding. We achieve 750 µJ temporally-shaped pulses of few nanoseconds at 1 kHz. Thanks to its original longitudinal geometry and its wide output core (26µm MFD), the Yb-doped tapered fiber used in the power amplifier stage ensures a single-mode operation and negligible spectro-temporal distortions. The transport of 30 kW peak power pulses (from tapered fiber) in a 17 m long large mode area (39µm) hollow-core (HC) fiber is presented and points out frequency modulation to amplitude modulation conversion management issues. A S² measurement of this fiber allows to attribute this conversion to a slightly multimode behavior (< 13dB of extinction between the fundamental mode and higher order modes). Other HC fibers exhibiting a really single-mode behavior (<20 dB) have been tested and the comparison will be presented in the conference. Finally, fiber spatial beam shaping from coherent Gaussian beam to coherent top-hat intensity profile beam in the mJ range with a specifically designed and fabricated fiber will also be presented.

  18. Signal generator system of phase laser range finder%野外大长度量值传递稳定性与可靠性分析

    Institute of Scientific and Technical Information of China (English)

    郭赞峰; 庞尚益

    2011-01-01

    In order to get a better modulated signal sources in phase laser range finder, microcontroller unit controlling with DDS chip AD9851 to generate adjustable frequency and controllable phase signal source was adopted in the paper. DDS has the low noise and high frequency resolution. It is easy to program and so on. According to reality, different frequency by AD9851 programming could be gained. It can meet the different distance measurement. High noise frequency always comes along with the signal source. Elliptic filter which is close to ideal low filter was designed for the filter. The paper gave the specific design steps, and got the amplitude - frequency characteristic curve through simulation software Pspice8. 0. The simulation result chart extremely approached the idealized characteristic curves. It laid the good foundation on the laser modulation of phase laser range finder.%因瓦基线尺是国家野外大长度量值传递的法定标准器,本文通过对一组因瓦基线尺多年的检定资料、基线场的多次测量成果以及与维塞拉光波干涉仪测量成果的比较分析,论述我国野外大长度量值传递的稳定性与可靠性.

  19. Compact sources for the generation of high-peak power wavelength-stabilized laser pulses in the picoseconds and nanoseconds ranges

    Science.gov (United States)

    Wenzel, H.; Klehr, A.; Schwertfeger, S.; Liero, A.; Hoffmann, Th.; Brox, O.; Thomas, M.; Erbert, G.; Tränkle, G.

    2012-03-01

    Diode lasers are ideally suited for the generation of optical pulses in the nanoseconds and picoseconds ranges by gainswitching, Q-switching or mode-locking. We have developed diode-laser based light sources where the pulses are spectrally stabilized and nearly-diffraction limited as required by many applications. Diffraction limited emission is achieved by a several microns wide ridge waveguide (RW), so that only the fundamental lateral mode should lase. Spectral stabilization is realized with a Bragg grating integrated into the semiconductor chip, resulting in distributed feedback (DFB) or distributed Bragg reflector (DBR) lasers. We obtained a peak power of 3.8W for 4ns long pulses using a gain-switched DFB laser and a peak power of more than 4W for 65ps long pulses using a three-section DBR laser. Higher peak powers of several tens of Watts can be reached by an amplification of the pulses with semiconductor optical amplifiers, which can be either monolithically or hybrid integrated with the master oscillators. We developed compact modules with a footprint of 4×5cm2 combining master oscillator, tapered power amplifier, beam-shaping optical elements and high-frequency electronics. In order to diminish the generation of amplified spontaneous emission between the pulses, the amplifier is modulated with short-pulses of high amplitude, too. Beyond the amplifier, we obtained a peak power of more than 10W for 4ns long pulses, a peak power of about 35W for 80ps long pulses and a peak power of 70W for 10ps long pulses at emission wavelengths around 1064nm.

  20. 3D laser-written silica glass step-index high-contrast waveguides for the 3.5 μm mid-infrared range.

    Science.gov (United States)

    Martínez, Javier; Ródenas, Airán; Fernandez, Toney; Vázquez de Aldana, Javier R; Thomson, Robert R; Aguiló, Magdalena; Kar, Ajoy K; Solis, Javier; Díaz, Francesc

    2015-12-15

    We report on the direct laser fabrication of step-index waveguides in fused silica substrates for operation in the 3.5 μm mid-infrared wavelength range. We demonstrate core-cladding index contrasts of 0.7% at 3.39 μm and propagation losses of 1.3 (6.5) dB/cm at 3.39 (3.68) μm, close to the intrinsic losses of the glass. We also report on the existence of three different laser modified SiO₂ glass volumes, their different micro-Raman spectra, and their different temperature-dependent populations of color centers, tentatively clarifying the SiO₂ lattice changes that are related to the large index changes.

  1. (In,Ga,Al)P–GaP laser diodes grown on high-index GaAs surfaces emitting in the green, yellow and bright red spectral range

    Science.gov (United States)

    Ledentsov, N. N.; Shchukin, V. A.; Shernyakov, Yu M.; Kulagina, M. M.; Payusov, A. S.; Gordeev, N. Yu; Maximov, M. V.; Cherkashin, N. A.

    2017-02-01

    We report on low threshold current density (region. Extended waveguide concept results in a vertical beam divergence with a full width at half maximum of 15° for (611)A substrates. The lasing at the wavelength of 569 nm is realized at 85 K. In an orange–red laser diode structure low threshold current density (190 A cm‑2) in the orange spectral range (598 nm) is realized at 85 K. The latter devices demonstrated room temperature lasing at 628 nm at ∼2 kA cm‑2 and a total power above 3 W. The red laser diodes grown on (211)A substrates demonstrated a far field characteristic for vertically multimode lasing indicating a lower optical confinement factor for the fundamental mode as compared to the devices grown on (611)A. However, as expected from previous research, the temperature stability of the threshold current and the wavelength stability were significantly higher for (211)A-grown structures.

  2. Application of laser ranging and VLBI data to a study of plate tectonic driving forces. [finite element method

    Science.gov (United States)

    Solomon, S. C.

    1980-01-01

    The measurability of changes in plate driving or resistive forces associated with plate boundary earthquakes by laser rangefinding or VLBI is considered with emphasis on those aspects of plate forces that can be characterized by such measurements. Topics covered include: (1) analytic solutions for two dimensional stress diffusion in a plate following earthquake faulting on a finite fault; (2) two dimensional finite-element solutions for the global state of stress at the Earth's surface for possible plate driving forces; and (3) finite-element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting.

  3. The key role of Satellite Laser Ranging towards the integrated estimation of geometry, rotation and gravitational field of the Earth

    Science.gov (United States)

    Blossfeld, Mathis

    2015-01-01

    In 2007, the Global Geodetic Observing System (GGOS) was installed as a full component of the International Association of Geodesy (IAG). One primary goal of GGOS is the integration of geometric and gravimetric observation techniques to estimate consistent geodetic-geophysical parameters. Thereby, GGOS is based on the data and services of the IAG. Besides the combination of different geodetic techniques, also the common estimation of the station coordinates (TRF), Earth Orientation Parameters (EOP) and coefficients of the Earth's gravitational field (Stokes coefficients) is necessary in order to reach this goal. However, the combination of all geometric and gravimetric observation techniques is not yet fully realized. A major step towards the GGOS idea of parameter integration would be the understanding of the existing correlations between the above mentioned fundamental geodetic parameter groups. This topic is the major objective of this thesis. One possibility to study the interactions is the use of Satellite Laser Ranging (SLR) in an intertechnique combination with Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI) or the intra-technique combination of multiple SLR-tracked satellites. SLR plays a key role in this thesis since it is the unique technique which is sensitive to all parameter groups and allows an integrated parameter estimation with very high accuracy. The present work is based on five first-author publications which are supplemented by four co-author publications. In this framework, for the first time an extensive discussion of a refined global Terrestrial Reference Frame (TRF) estimation procedure, the estimation of so-called Epoch Reference Frames (ERFs) is presented. In contrast to the conventional linear station motion model, the ERFs provide frequently estimated station coordinates and Earth Orientation Parameters (EOP) which allow to approximate not modeled non-linear station motions very accurately

  4. EDGE3: A web-based solution for management and analysis of Agilent two color microarray experiments

    Directory of Open Access Journals (Sweden)

    Craven Mark

    2009-09-01

    Full Text Available Abstract Background The ability to generate transcriptional data on the scale of entire genomes has been a boon both in the improvement of biological understanding and in the amount of data generated. The latter, the amount of data generated, has implications when it comes to effective storage, analysis and sharing of these data. A number of software tools have been developed to store, analyze, and share microarray data. However, a majority of these tools do not offer all of these features nor do they specifically target the commonly used two color Agilent DNA microarray platform. Thus, the motivating factor for the development of EDGE3 was to incorporate the storage, analysis and sharing of microarray data in a manner that would provide a means for research groups to collaborate on Agilent-based microarray experiments without a large investment in software-related expenditures or extensive training of end-users. Results EDGE3 has been developed with two major functions in mind. The first function is to provide a workflow process for the generation of microarray data by a research laboratory or a microarray facility. The second is to store, analyze, and share microarray data in a manner that doesn't require complicated software. To satisfy the first function, EDGE3 has been developed as a means to establish a well defined experimental workflow and information system for microarray generation. To satisfy the second function, the software application utilized as the user interface of EDGE3 is a web browser. Within the web browser, a user is able to access the entire functionality, including, but not limited to, the ability to perform a number of bioinformatics based analyses, collaborate between research groups through a user-based security model, and access to the raw data files and quality control files generated by the software used to extract the signals from an array image. Conclusion Here, we present EDGE3, an open-source, web

  5. Large-Mode-Area Double-Cladding Photonic Crystal Fiber Laser in the Watt Range at 980 nm

    Institute of Scientific and Technical Information of China (English)

    LI Ping-Xue; ZHANG Xue-Xia; LIU Zhi; CHI Jun-Jie

    2011-01-01

    @@ We report on a quasi-three-level large-mode-area double-clad Yb-doped fiber laser that adopts a linear cavity consisting of a 0°fiber end and a cavity mirror.Two kinds of Yb-doped photonic crystal fiber(PCF) with different inner-clads (170 μm and 200μm) and absorption coefficients (4.5 dB/m and 3 dB/m) are used as the gain media.By optimizing the structure and elements of the cavity, maximum output powers of 1.24 W and 1.1 W were yielded with optical conversion efficiencies of 7.8% and 6.8% when the fiber lengths were 25 cm and 40 cm with 170μm and 200 μm inner-claddings, respectively.

  6. Mobile robot self-localization in unstructured environments based on observation localizability estimation with low-cost laser range-finder and RGB-D sensors

    Directory of Open Access Journals (Sweden)

    Kun Qian

    2016-10-01

    Full Text Available When service robots work in human environments, unexpected and unknown moving people may deteriorate the convergence of robot localization or even cause failure localization if the environment is crowded. In this article, a multisensor observation localizability estimation method is proposed and implemented for supporting reliable robot localization in unstructured environments with low-cost sensors. The contribution of the approach is a strategy that combines noisy laser range-finder data and RGB-D data for estimating the dynamic localizability matrix in a probabilistic framework. By aligning two sensor frames, the unreliable part of the laser readings that hits unexpected moving people is fast extracted according to the output of a RGB-D-based human detector, so that the influence of unexpected moving people on laser observations can be explicitly factored out. The method is easy for implementation and is highly desirable to ensure robustness and real-time performance for long-term operation in populated environments. Comparative experiments are conducted and the results confirm the effectiveness and reliability of the proposed method in improving the localization accuracy and reliability in dynamic environments.

  7. High-Precision Surface Inspection: Uncertainty Evaluation within an Accuracy Range of 15μm with Triangulation-based Laser Line Scanners

    Science.gov (United States)

    Dupuis, Jan; Kuhlmann, Heiner

    2014-06-01

    Triangulation-based range sensors, e.g. laser line scanners, are used for high-precision geometrical acquisition of free-form surfaces, for reverse engineering tasks or quality management. In contrast to classical tactile measuring devices, these scanners generate a great amount of 3D-points in a short period of time and enable the inspection of soft materials. However, for accurate measurements, a number of aspects have to be considered to minimize measurement uncertainties. This study outlines possible sources of uncertainties during the measurement process regarding the scanner warm-up, the impact of laser power and exposure time as well as scanner’s reaction to areas of discontinuity, e.g. edges. All experiments were performed using a fixed scanner position to avoid effects resulting from imaging geometry. The results show a significant dependence of measurement accuracy on the correct adaption of exposure time as a function of surface reflectivity and laser power. Additionally, it is illustrated that surface structure as well as edges can cause significant systematic uncertainties.

  8. Assessment of the accuracy of global geodetic satellite laser ranging observations and estimated impact on ITRF scale: estimation of systematic errors in LAGEOS observations 1993-2014

    Science.gov (United States)

    Appleby, Graham; Rodríguez, José; Altamimi, Zuheir

    2016-12-01

    Satellite laser ranging (SLR) to the geodetic satellites LAGEOS and LAGEOS-2 uniquely determines the origin of the terrestrial reference frame and, jointly with very long baseline interferometry, its scale. Given such a fundamental role in satellite geodesy, it is crucial that any systematic errors in either technique are at an absolute minimum as efforts continue to realise the reference frame at millimetre levels of accuracy to meet the present and future science requirements. Here, we examine the intrinsic accuracy of SLR measurements made by tracking stations of the International Laser Ranging Service using normal point observations of the two LAGEOS satellites in the period 1993 to 2014. The approach we investigate in this paper is to compute weekly reference frame solutions solving for satellite initial state vectors, station coordinates and daily Earth orientation parameters, estimating along with these weekly average range errors for each and every one of the observing stations. Potential issues in any of the large number of SLR stations assumed to have been free of error in previous realisations of the ITRF may have been absorbed in the reference frame, primarily in station height. Likewise, systematic range errors estimated against a fixed frame that may itself suffer from accuracy issues will absorb network-wide problems into station-specific results. Our results suggest that in the past two decades, the scale of the ITRF derived from the SLR technique has been close to 0.7 ppb too small, due to systematic errors either or both in the range measurements and their treatment. We discuss these results in the context of preparations for ITRF2014 and additionally consider the impact of this work on the currently adopted value of the geocentric gravitational constant, GM.

  9. High harmonic generation in a two-color field composed of a pump field and a weak subsidiary high frequency field

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    “Coherent control of high-harmonic generation in a two-color field” has been widely concerned. Using split-operator algorithm, we have calculated the high-harmonic generation for helium ion He+ in a two-color field which is composed of a driving field and a weak subsidiary high frequency field (Is=I0/100, (ω,13ω), …(ω, 120ω)) and found that such a field can produce much higher harmonic intensity, typically increasing the harmonics corresponding to the incident frequency of the subsidiary field. The different effects coming from the different subsidiary fields are calculated and analyzed. It is indicated that one of the important underlying mechanisms is high frequency photon induced radiation.

  10. Identification of the origin of marker chromosomes by two-color fluorescence in situ hybridization and polymerase chain reaction in azoospermic patients.

    Science.gov (United States)

    Wei, C L; Cheng, J L; Yang, W C; Li, L Y; Cheng, H C; Fu, J J

    2015-11-19

    Y chromosomal microdeletions at the azoospermia factor locus and chromosome abnormalities have been implicated as the major causes of idiopathic male infertility. A marker chromosome is a structurally abnormal chromosome in which no part can be identified by cytogenetics. In this study, to identify the origin of the marker chromosomes and to perform a genetic diagnosis of patients with azoospermia, two-color fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) techniques were carried out. The marker chromosomes for the two patients with azoospermia originated in the Y chromosome; it was ascertained that the karyotype of both patients was 46,X, ish del(Y)(q11)(DYZ3+, DXZ1-). The combination of two-color FISH and PCR techniques is an important method for the identification of the origin of marker chromosomes. Thus, genetic counseling and a clear genetic diagnosis of patients with azoospermia before intracytoplasmic sperm injection or other clinical managements are important.

  11. Two-color injection mould for the handle of egg mixer%鸡蛋搅拌机手柄双色注射模设计

    Institute of Scientific and Technical Information of China (English)

    陈罡; 陈乐平; 毛金明

    2012-01-01

    The structure layout, design points and working process of a two-color injection mould for the handle of an egg mixer were analyzed; and the design of gating system was presented in detail. The application of composite half-mechanism and mechanism of core-pulling by inclined ejector pin achieves sequential parting of the two-color mould.%分析了鸡蛋搅拌机手柄双色注射模的结构、设计要点和工作过程,详细介绍了模具浇注系统设计,采用复合哈夫机构和斜推杆内抽芯机构,实现了双色模具顺序分型动作.实践表明,模具结构可靠,运动平稳顺畅,制品精度和外观质量均符合要求.

  12. How do we select multiple features? Transient costs for selecting two colors rather than one, persistent costs for color-location conjunctions.

    Science.gov (United States)

    Lo, Shih-Yu; Holcombe, Alex O

    2014-02-01

    In a previous study Lo, Howard, & Holcombe (Vision Research 63:20-33, 2012), selecting two colors did not induce a performance cost, relative to selecting one color. For example, requiring possible report of both a green and a red target did not yield a worse performance than when both targets were green. Yet a cost of selecting multiple colors was observed when selection needed be contingent on both color and location. When selecting a red target to the left and a green target to the right, superimposing a green distractor to the left and a red distractor to the right impeded performance. Possibly, participants cannot confine attention to a color at a particular location. As a result, distractors that share the target colors disrupt attentional selection of the targets. The attempt to select the targets must then be repeated, which increases the likelihood that the trial terminates when selection is not effective, even for long trials. Consistent with this, here we find a persistent cost of selecting two colors when the conjunction of color and location is needed, but the cost is confined to short exposure durations when the observer just has to monitor red and green stimuli without the need to use the location information. These results suggest that selecting two colors is time-consuming but effective, whereas selection of simultaneous conjunctions is never entirely successful.

  13. The Three-Color and Two-Color Tantrix(TM) Rotation Puzzle Problems are NP-Complete via Parsimonious Reductions

    CERN Document Server

    Baumeister, Dorothea

    2007-01-01

    Holzer and Holzer (Discrete Applied Mathematics 144(3):345--358, 2004) proved the Tantrix(TM) rotation puzzle problem with four colors NP-complete. Baumeister and Rothe (MCU 2007) modified their construction to achieve a parsimonious reduction from satisfiability to this problem. Since parsimonious reductions preserve the number of solutions, it follows that the unique version of the four-color Tantrix(TM) rotation puzzle problem is DP-complete under randomized reductions. In this paper, we study the three-color and the two-color Tantrix(TM) rotation puzzle problem. Restricting the number of allowed colors to three (respectively, to two) reduces the set of available Tantrix(TM) tiles from 56 to 14 (respectively, to 8). We prove that both the three-color and the two-color Tantrix(TM) rotation puzzle problem is NP-complete, which answers a question raised by Holzer and Holzer in the affirmative. Since both these reductions are parsimonious, it follows that both the unique three-color and the unique two-color Ta...

  14. Magnetizing NIF Sub-Scale Capsules For Reaching Ignition Using Laser Energy in the 1 MJ Range

    Science.gov (United States)

    Zimmerman, G.; Ho, D.; Perkins, J.; Kagan, G.; Logan, G.; Salmonson, J.; Rhodes, M.; Blackfield, D.

    2016-10-01

    Fusion yield for ICF can be amplified by imposing a seed B-field around 50 T to confine alphas and to reduce electron heat conduction. Achieving 58 T in offline lab tests in sample hohlraum coils driven by a pulsed-power supply was demonstrated by Rhodes. Three topics are addressed. (1) The derivation of a 0D energy balance equation that including the effect of B-field. The ignition boundary obtained from this equation shows that a strong compressed B-field substantially reduces the minimum hotspot ρR required for ignition by about 50%. (2) The design of a near-term experimental demonstration of the effect of B-field on yield improvement based on our sub-scale gas-filled Symcap design for the NIF experiment (non-magnetized) that gave 1D yield and showed good symmetry. (3) The quest and design of magnetized sub-scale capsule with DT ice layer that gives robust ignition and requires only about 1 MJ of laser energy. Our baseline non-magnetized sub-scale design, with a seed field of 50T, gives a robust ignition with 1 MJ yield. This work performed under auspices of U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

  15. Soft x-ray free-electron laser imaging by LiF crystal and film detectors over a wide range of fluences.

    Science.gov (United States)

    Pikuz, Tatiana A; Faenov, Anatoly Ya; Fukuda, Yuji; Kando, Masaki; Bolton, Paul; Mitrofanov, Alexander; Vinogradov, Alexander V; Nagasono, Mitsuru; Ohashi, Haruhiko; Yabashi, Makina; Tono, Kensuke; Senba, Yasunori; Togashi, Tadashi; Ishikawa, Tetsuya

    2013-01-20

    LiF crystal and film detectors were used to measure the far-field fluence profile of a self-amplified spontaneous-emission free-electron laser beam and diffraction imaging with high spatial resolution. In these measurements the photoluminescence (PL) response of LiF crystal and film was compared over a wide range of soft x-ray fluences. It was found that the soft x-ray fluence dependences of LiF crystal and film differ. At low fluence, the LiF crystal shows higher PL response compared to LiF film, while this comparison is the opposite at higher fluence. Accurate measurement of LiF crystal and film PL response is important for precise characterization of the spatial, spectral, and coherence features of x-ray beams across the full profile and in localized areas. For such measurements, crucial LiF detector attributes are high spatial resolution and high dynamic range.

  16. Nine orders of magnitude dynamic range: picomolar to millimolar concentration measurement in capillary electrophoresis with laser induced fluorescence detection employing cascaded avalanche photodiode photon counters.

    Science.gov (United States)

    Dada, Oluwatosin O; Essaka, David C; Hindsgaul, Ole; Palcic, Monica M; Prendergast, Jillian; Schnaar, Ronald L; Dovichi, Norman J

    2011-04-01

    The dynamic range of capillary electrophoresis analysis is ultimately limited by molecular shot noise at low concentrations and by concentration-induced band broadening at high concentrations. We report a system that approaches these fundamental limits. A laser-induced fluorescence detector is reported that employs a cascade of four fiber-optic beam splitters connected in series to generate a primary signal and four attenuated signals, each monitored by a single-photon counting avalanche photodiode. Appropriate scaling of the signals from the five photodiodes produces a linear optical calibration curve for 5-carboxyl-tetramethylrhodamine from the concentration detection limit of 1 pM to the upper limit of 1 mM. Mass detection limits are 120 yoctomoles (70 molecules) injected into the instrument. The very-wide dynamic range instrument was used to study the metabolic products of the fluorescently labeled glycosphingolipid tetramethylrhodamine labeled GM1 (GM1-TMR) produced by single cells isolated from the rat cerebellum.

  17. Pixel multiplexing technique for real-time three-dimensional-imaging laser detection and ranging system using four linear-mode avalanche photodiodes.

    Science.gov (United States)

    Xu, Fan; Wang, Yuanqing; Li, Fenfang

    2016-03-01

    The avalanche-photodiode-array (APD-array) laser detection and ranging (LADAR) system has been continually developed owing to its superiority of nonscanning, large field of view, high sensitivity, and high precision. However, how to achieve higher-efficient detection and better integration of the LADAR system for real-time three-dimensional (3D) imaging continues to be a problem. In this study, a novel LADAR system using four linear mode APDs (LmAPDs) is developed for high-efficient detection by adopting a modulation and multiplexing technique. Furthermore, an automatic control system for the array LADAR system is proposed and designed by applying the virtual instrumentation technique. The control system aims to achieve four functions: synchronization of laser emission and rotating platform, multi-channel synchronous data acquisition, real-time Ethernet upper monitoring, and real-time signal processing and 3D visualization. The structure and principle of the complete system are described in the paper. The experimental results demonstrate that the LADAR system is capable of achieving real-time 3D imaging on an omnidirectional rotating platform under the control of the virtual instrumentation system. The automatic imaging LADAR system utilized only 4 LmAPDs to achieve 256-pixel-per-frame detection with by employing 64-bit demodulator. Moreover, the lateral resolution is ∼15 cm and range accuracy is ∼4 cm root-mean-square error at a distance of ∼40 m.

  18. Pixel multiplexing technique for real-time three-dimensional-imaging laser detection and ranging system using four linear-mode avalanche photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Fan; Wang, Yuanqing, E-mail: yqwang@nju.edu.cn; Li, Fenfang [School of Electronic Science and Engineering, Nanjing University, Nanjing 210046 (China)

    2016-03-15

    The avalanche-photodiode-array (APD-array) laser detection and ranging (LADAR) system has been continually developed owing to its superiority of nonscanning, large field of view, high sensitivity, and high precision. However, how to achieve higher-efficient detection and better integration of the LADAR system for real-time three-dimensional (3D) imaging continues to be a problem. In this study, a novel LADAR system using four linear mode APDs (LmAPDs) is developed for high-efficient detection by adopting a modulation and multiplexing technique. Furthermore, an automatic control system for the array LADAR system is proposed and designed by applying the virtual instrumentation technique. The control system aims to achieve four functions: synchronization of laser emission and rotating platform, multi-channel synchronous data acquisition, real-time Ethernet upper monitoring, and real-time signal processing and 3D visualization. The structure and principle of the complete system are described in the paper. The experimental results demonstrate that the LADAR system is capable of achieving real-time 3D imaging on an omnidirectional rotating platform under the control of the virtual instrumentation system. The automatic imaging LADAR system utilized only 4 LmAPDs to achieve 256-pixel-per-frame detection with by employing 64-bit demodulator. Moreover, the lateral resolution is ∼15 cm and range accuracy is ∼4 cm root-mean-square error at a distance of ∼40 m.

  19. Effects of laser frequency chirp on modal noise in short-range radio over multimode fiber links

    DEFF Research Database (Denmark)

    Visani, Davide; Tartarini, Giovanni; Petersen, Martin Nordal;

    2010-01-01

    An important effect of the frequency chirp of the optical transmitter in radio over multimode fiber links is put into evidence experimentally and modeled theoretically for the first time, to our knowledge. This effect can have an important impact in short-range connections, where, although...

  20. Accurate displacement-measuring interferometer with wide range using an I2 frequency-stabilized laser diode based on sinusoidal frequency modulation

    Science.gov (United States)

    Vu, Thanh-Tung; Higuchi, Masato; Aketagawa, Masato

    2016-10-01

    We propose the use of the sinusoidal frequency modulation technique to improve both the frequency stability of an external cavity laser diode (ECLD) and the measurement accuracy and range of a displacement-measuring interferometer. The frequency of the ECLD was modulated at 300 kHz by modulating the injection current, and it was locked to the b21 hyperfine component of the transition 6-3, P(33), 127I2 (633 nm) by the null method. A relative frequency stability of 6.5  ×  10-11 was achieved at 100 s sampling time. The stabilized ECLD was then utilized as a light source for an unbalanced Michelson interferometer. In the interferometer, the displacement and direction of the target mirror can be determined using a Lissajous diagram based on two consecutive and quadrant-phase harmonics of the interference signal. Generally, the measurement range of the interferometer by the proposed method is limited by the modulation index and the signal-to-noise ratio of the harmonics. To overcome this drawback, suitable consecutive harmonic pairs were selected for the specific measurement ranges to measure the displacement. The displacements determined in the specific ranges by the proposed method were compared with those observed by a commercial capacitive sensor. From the comparison, the proposed method has high precision to determine the displacement. The measurement range was also extended up to 10 m by selecting a suitable modulation index and suitable consecutive pairs of harmonics.

  1. High dynamic range measurement of spectral responsivity and linearity of a radiation thermometer using a super-continuum laser and LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Y. S.; Lee, D. H.; Park, C. W.; Park, S. N. [Korea Research Institute of Standards and Science 209 Gajeong-Ro, Yuseong-Gu, Daejon 305-340 (Korea, Republic of)

    2013-09-11

    To realize the temperature scale above the freezing point of silver according to the definition of ITS-90, the dynamic range of the spectral responsivity is one of the most important factors which limit its uncertainty. When the residual spectral response at both side bands of a spectral band is not negligible, a significant uncertainty can be caused by a low dynamic range of the spectral responsivity measurement. In general, incandescent lamps are used to measure the spectral responsivity and the linearity. The dynamic range of the spectral responsivity measurement is often limited by a trade-off with the desired spectral resolution, which is less than 6 decades. Nonlinearity is another limiting fact of uncertainties of the temperature scale. Tungsten lamps have disadvantage in the nonlinearity measurements in terms of adjustability of radiance level and spectral selectivity. We report spectral responsivity measurements of which the measurable dynamic range is enhanced 50 times after replacing a QTH lamp with a super continuum laser. We also present a spectrally selected linearity measurement over a wide dynamic range using high-brightness light emitting diode arrays to observe a slight saturation of linearity.

  2. Wide-Band Spatially Tunable Photonic Bandgap in Visible Spectral Range and Laser based on a Polymer Stabilized Blue Phase

    OpenAIRE

    2016-01-01

    This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing. This gradient-pitched PSBP can show a rainbow-like reflec...

  3. Seeded free-electron and inverse free-electron laser techniques for radiation amplification and electron microbunching in the terahertz range

    Directory of Open Access Journals (Sweden)

    C. Sung

    2006-12-01

    Full Text Available A comprehensive analysis is presented that describes amplification of a seed THz pulse in a single-pass free-electron laser (FEL driven by a photoinjector. The dynamics of the radiation pulse and the modulated electron beam are modeled using the time-dependent FEL code, GENESIS 1.3. A 10-ps (FWHM electron beam with a peak current of 50–100 A allows amplification of a ∼1  kW seed pulse in the frequency range 0.5–3 THz up to 10–100 MW power in a relatively compact 2-m long planar undulator. The electron beam driving the FEL is strongly modulated, with some inhomogeneity due to the slippage effect. It is shown that THz microbunching of the electron beam is homogeneous over the entire electron pulse when saturated FEL amplification is utilized at the very entrance of an undulator. This requires seeding of a 30-cm long undulator buncher with a 1–3 MW of pump power with radiation at the resonant frequency. A narrow-band seed pulse in the THz range needed for these experiments can be generated by frequency mixing of CO_{2} laser lines in a GaAs nonlinear crystal. Two schemes for producing MW power pulses in seeded FELs are considered in some detail for the beam parameters achievable at the Neptune Laboratory at UCLA: the first uses a waveguide to transport radiation in the 0.5–3 THz range through a 2-m long FEL amplifier and the second employs high-gain third harmonic generation using the FEL process at 3–9 THz.

  4. Design of Laser Range Finder Based on TDC_GP21%基于TDC_GP21的激光测距仪设计

    Institute of Scientific and Technical Information of China (English)

    纪晓轮; 蒋钱; 陈江伟; 张旭野

    2015-01-01

    为提高激光测距仪测距精度,采用ACAM公司的时间数字转换芯片TDC_GP21,设计了高精度的时间间隔测量模块,采用数据拟合算法对测距系统进行了标定,并用多项测距算术平均值的方法提高系统测距精度.测量结果表明系统电路简单、精度较高、成本更低、具有量产可行性.%In order to improve the ranging accuracy of laser range finder,we used the time digital converter chip TDC_GP21 of ACAM,designing a high precision time interval measurement module,using data fitting algorithm to calibrate the ranging system,and the average value of multiple ranging arithmetic is used to improve the accuracy of the system.The measurement results show that the circuit is simple,the precision is high,the cost is lower,and it has the feasibility of mass production.

  5. Thermomechanical response of 3D laser-deposited Ti–6Al–4V alloy over a wide range of strain rates and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peng-Hui [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Guo, Wei-Guo, E-mail: weiguo@nwpu.edu.cn [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Huang, Wei-Dong [The State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Su, Yu [Department of Mechanics, School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Lin, Xin [The State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Yuan, Kang-Bo [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China)

    2015-10-28

    To understand and evaluate the thermomechanical property of Ti–6Al–4V alloy prepared by the 3D laser deposition technology, an uniaxial compression test was performed on cylindrical samples using an electronic universal testing machine and enhanced Hopkinson technique, over the range of strain rate from 0.001/s to 5000/s, and at initial temperatures from the room temperature to 1173 K. The microstructure of the undeformed and deformed samples was examined through optical microscopy and the use of scanning electron microscope (SEM). The experimental results show the followings: (1) the anisotropy of the mechanical property of this alloy is not significant despite the visible stratification at the exterior surfaces; (2) initial defects, such as the initial voids and lack of fusion, are found in the microstructure and in the crack surfaces of the deformed samples, and they are considered as a major source of crack initiation and propagation; (3) adiabatic shear bands and shearing can easily develop at all selected temperatures for samples under compression; (4) the yield and ultimate strengths of this laser-deposited Ti–6Al–4V alloy are both lower than those of the Ti–6Al–4V alloy prepared by forging and electron beam melting, whereas both of its strengths are higher than those of a conventional grade Ti–6Al–4V alloy at high strain rate only. In addition to compression tests we also conducted tensile loading tests on the laser-deposited alloy at both low and high strain rates (0.1/s and 1000/s). There is significant tension/compression asymmetry in the mechanical response under high-strain-rate loading. It was found that the quasi-static tensile fracturing exhibits typical composite fracture characteristic with quasi-cleavages and dimples, while the high-strain-rate fracturing is characterized by ductile fracture behavior.

  6. The Optoelectronic Swept-Frequency Laser and Its Applications in Ranging, Three-Dimensional Imaging, and Coherent Beam Combining of Chirped-Seed Amplifiers

    Science.gov (United States)

    Vasilyev, Arseny

    This thesis explores the design, construction, and applications of the optoelectronic swept-frequency laser (SFL). The optoelectronic SFL is a feedback loop designed around a swept-frequency (chirped) semiconductor laser (SCL) to control its instantaneous optical frequency, such that the chirp characteristics are determined solely by a reference electronic oscillator. The resultant system generates precisely controlled optical frequency sweeps. In particular, we focus on linear chirps because of their numerous applications. We demonstrate optoelectronic SFLs based on vertical-cavity surface-emitting lasers (VCSELs) and distributed-feedback lasers (DFBs) at wavelengths of 1550 nm and 1060 nm. We develop an iterative bias current predistortion procedure that enables SFL operation at very high chirp rates, up to 1016 Hz/sec. We describe commercialization efforts and implementation of the predistortion algorithm in a stand-alone embedded environment, undertaken as part of our collaboration with Telaris, Inc. We demonstrate frequency-modulated continuous-wave (FMCW) ranging and three-dimensional (3-D) imaging using a 1550 nm optoelectronic SFL. We develop the technique of multiple source FMCW (MS-FMCW) reflectometry, in which the frequency sweeps of multiple SFLs are "stitched" together in order to increase the optical bandwidth, and hence improve the axial resolution, of an FMCW ranging measurement. We demonstrate computer-aided stitching of DFB and VCSEL sweeps at 1550 nm. We also develop and demonstrate hardware stitching, which enables MS-FMCW ranging without additional signal processing. The culmination of this work is the hardware stitching of four VCSELs at 1550 nm for a total optical bandwidth of 2 THz, and a free-space axial resolution of 75 microns. We describe our work on the tomographic imaging camera (TomICam), a 3-D imaging system based on FMCW ranging that features non-mechanical acquisition of transverse pixels. Our approach uses a combination of

  7. Raman laser based on a KGd(WO4)2 crystal: generation of stokes components in the 1.7-1.8 μm range*

    Science.gov (United States)

    Dashkevich, V. I.; Orlovich, V. A.

    2013-01-01

    We have studied the lasing characteristics of a Raman laser based on an Nd:KGW crystal, converting multimode emission of a pulsed Nd:KGW laser with working transition 4F3/2-4I13/2 (1351 nm) to Stokes components with wavelengths in the 1700-1800 nm range. We show that when the pump polarization coincides with the N m axis of the optical indicatrix of KGW ( E || N m ), the conversion efficiency for converting the pump radiation to the single second Stokes component with λ ~ 1786 nm reaches 17.5%, which results in an ~6.6 mJ Raman pulse. For E || N g , the conversion efficiency increases up to 22.5% and generation of an ~15 ns pulse occurs on four Stokes components with wavelengths 1704, 1744, 1770, and 1786 nm due to involvement of 86 cm-1, 767 cm-1, and 901 cm-1 vibrational modes in the stimulated Raman (SRS) process. We have determined the spectral distribution of the pulse energy. A total of 11 Stokes components are generated with participation of the indicated vibrational modes.

  8. Deep-space laser-ranging missions ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I for astrodynamics and astrometry

    CERN Document Server

    Ni, Wei-Tou

    2007-01-01

    Deep-space laser ranging will be ideal for testing relativistic gravity, and mapping the solar-system to an unprecedented accuracy. ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I are such missions. ASTROD I is a mission with a single spacecraft; it is the first step of ASTROD with 3 spacecraft. In this talk, after a brief review of ASTROD and ASTROD I, we concentrate of the precision of solar astrodynamics that can be achieved together with implications on astrometry and reference frame transformations. The precision planetary ephemeris derived from these missions together with second post-Newtonian test of relativistic gravity will serve as a foundation for future precise astrometry observations. Relativistic frameworks are discussed from these considerations.

  9. Laser-optical measurements of the velocities of the plasma jets formed from different gases in a kilojoule-range plasma focus facility

    Energy Technology Data Exchange (ETDEWEB)

    Polukhin, S. N., E-mail: snpol@lebedev.ru; Dzhamankulov, A. M.; Gurei, A. E.; Nikulin, V. Ya., E-mail: vnik@lebedev.ru; Peregudova, E. N.; Silin, P. V. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2016-12-15

    The velocities of the plasma jets formed from Ne, N{sub 2}, Ar, and Xe gases in plasma focus facilities were determined by means of laser-optical shadowgraphy of the shock waves generated at the jet leading edge. In spite of the almost tenfold ratio between the atomic weights of these gases, the outflow velocities of the plasma jets formed in experiments with these gases differ by less than twice, in the range of (0.7–1.1) × 10{sup 7} cm/s under similar discharge conditions. The energies of the jet ions were found to vary from 0.7 keV for nitrogen to 4 keV for xenon.

  10. Detection System of Ranging Precision for Laser Rangefinder%大量程激光测距仪精度检测系统

    Institute of Scientific and Technical Information of China (English)

    董洪舟; 杨若夫; 敖明武; 李绍荣; 严高师

    2013-01-01

    The ranging precision is an important indicator to measure the performance of laser rangefinder. A detection system of ranging precision for 1 064 nm, 1 540 nm, and 1 570 nm wavelength rangefinder was introduced. The system consists of distance simulator and laser radiation simulator. Radiation simulator can generate an echo pulse with width among 5∼250 ns and the maximum peak power 0.1 W. FPGA-based distance simulator can realize distance simulation during 50 m∼990 km. The closed-loop detection method between radiation simulator and distance simulator is proposed and realized. According to the method, the fixed error of detection system is measured and eliminated. The detection results show that the distance simulation error is less than 1 meter in full simulation scale.%  激光测距仪的测距精度是衡量其性能的重要指标.本文设计了测距精度检测系统,可实现1064 nm、1540 nm、1570 nm三个波长的测距仪精度检测.该系统由激光距离模拟器和激光辐射模拟器组成,辐射模拟器可产生脉宽5∼250 ns、最大峰值功率0.1 W的回波脉冲;基于FPGA的距离模拟器可以实现50 m∼990 km的大量程距离模拟.本文提出并实现辐射模拟器和距离模拟器的闭环检测,以此测量消除系统固定误差.经过检测该系统全量程内距离模拟误差都小于1 m.

  11. Signal generator system of phase laser range finder%相位法激光测距信号源系统研究

    Institute of Scientific and Technical Information of China (English)

    姜明富; 曾一凡; 杨艳

    2011-01-01

    In order to get a better modulated signal sources in phase laser range finder, microcontroller unit controlling with DDS chip AD9851 to generate adjustable frequency and controllable phase signal source was adopted in the paper. DDS has the low noise and high frequency resolution. It is easy to program and so on. According to reality, different frequency by AD9851 programming couldbe gained. It can meet the different distance measurement. High noise frequency always comes along with the signal source. Elliptic filter which is close to ideal low filter was designed for the filter. The paper gave the specific design steps, and got the amplitude - frequency characteristic curve through simulation software Pspice8. 0. The simulation result chart extremely approached the idealized characteristic curves. It laid the good foundation on the laser modulation of phase laser range finder.%为了使相位式激光测距获得更好的调制信号源,采用了基于单片机控制DDA芯片AD9851产生频率可调,相位可控的信号源,由于DDS具有噪声低,频率分辨率高,易于编程等优点,根据实际需要,通过给AD9851编程获得不同的频率,满足不同距离的测量.由于获得的信号源中存在着高频杂散信号,设计了最接近理想特性的椭圆低通滤波器,并给出具体的设计步骤,通过Pspice8.0仿真软件仿真出幅频特性曲线,仿真的结果图非常逼近理想特性,为相位法激光测距中调制部分需要高纯度信号源提供前提条件.

  12. Extended dynamic range of Doppler OCT by application of a new method to high density B-scans using a MHz FDML swept laser source (Conference Presentation)

    Science.gov (United States)

    Elahi, Sahar; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

    2017-02-01

    The limited dynamic range of optical coherence tomography (OCT) Doppler velocity measurements makes it difficult to conduct experiments on samples requiring a large dynamic range without phase wrapping at high velocities or loss of sensitivity at slow velocities. Hemodynamics and wall motion undergo significant increases in velocity as the embryonic heart develops. Experimental studies indicate that altered hemodynamics in early-stage embryonic hearts can lead to congenital heart diseases (CHDs), motivating close monitoring of blood flow over several stages of development. We have built a high-speed OCT system using an FDML laser (Optores GmbH, Germany) at a sweep rate of 1.68 MHz (axial resolution - 12 μm, sensitivity - 105 dB, phase stability - 17 mrad). The speed of this OCT system allows us to acquire high-density B-scans to obtain an extended velocity dynamic range without sacrificing the frame rate (100 Hz). The extended dynamic range within a frame is achieved by varying the A-scan interval at which the phase difference is found, enabling detection of velocities ranging from tens of microns per second to hundreds of millimeters per second. The extra lines in a frame can also be utilized to improve the structural and Doppler images via complex averaging. In structural images where the presence of blood causes additional scattering, complex averaging helps retrieve features located deeper in the tissue. Moreover, high-density frames can be registered to 4D volumes to determine the orthogonal direction of flow for calculating shear stress as well as estimating the cardiac output. In conclusion, high density B-scans acquired by our high-speed OCT system enable image enhancement and direct measurement of biological parameters in cohort studies.

  13. Automated assessment of blood flow in developing embryonic hearts by extending dynamic range of Doppler OCT using a MHz FDML swept laser source (Conference Presentation)

    Science.gov (United States)

    Elahi, Sahar; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

    2017-02-01

    Altered hemodynamics in developing embryonic hearts lead to congenital heart diseases, motivating close monitoring of blood flow over several stages of development. Doppler OCT can assess blood flow in tubular hearts, but the maximum velocity increases drastically during the period of cardiac cushion (valve precursors) formation. Therefore, the limited dynamic range of Doppler OCT velocity measurement makes it difficult to conduct longitudinal studies without phase wrapping at high velocities or loss of sensitivity to slow velocities. We have built a high-speed OCT system using an FDML laser (Optores GmbH, Germany) at a sweep rate of 1.68 MHz (axial resolution - 12 μm, sensitivity - 105 dB, phase stability - 17 mrad). The speed of this OCT system allows us to acquire high-density B-scans to obtain an extended velocity dynamic range without sacrificing the frame rate. The extended dynamic range within a frame is achieved by varying the A-scan interval at which the phase difference is found, enabling detection of velocities ranging from tens of microns per second to hundreds of mm per second. The extra lines in a frame can also be utilized to improve the structural and Doppler images via complex averaging. In structural images where presence of blood causes additional scattering, complex averaging helps retrieve features located deeper in the tissue. Moreover, high-density frames can be registered to 4D volumes to determine the orthogonal direction of flow and calculate shear stress. In conclusion, our high-speed OCT system will enable automated Doppler imaging of embryonic hearts in cohort studies.

  14. P1-9: Relationship between Color Shifts in Land's Two-Color Method and Higher- and Lower-Level Visual Information

    Directory of Open Access Journals (Sweden)

    Saki Iwaida

    2012-10-01

    Full Text Available Land's two-color method gives rise to apparent full-color perception, even though only two colors (e.g., red and gray are used. Previous studies indicate that chromatic adaptation, color memory, and inductive effects contribute to the shifts of color perception from real to illusory colors (e.g., Kuriki, 2006 Vision Research 46 3055–3066. This paper investigates the relationship between the color shifts induced by Land images and the skewness of the luminance histogram. In Experiment 1, several Land images are created based on a yellow ball, and the magnitude of the color shifts of the images are measured. The results of Experiment 1 show a significant correlation between the magnitude of the color shifts and skewness, suggesting that skewness is critical for the color shifts. In Experiment 2, we test the hypothesis that color shifts depends on just skewness; the color shifts should be invariant even if the Land images are scrambled. However, the results of Experiment 2 demonstrate that scrambled Land images exhibit less intense color shifts, suggesting that color shifts are determined by the object's overall shape or surface gloss, not just skewness. Taken together, we conclude that both low-level visual processes, such as those associated with luminance histogram skew, and high-level cognitive functions, such as object interpretation or understanding of surface gloss, are involved in the color shift of Land images.

  15. 脉冲激光测距的时间间隔测量方法%Method of Measurement on Time-Interval in Pulsed Laser Ranging

    Institute of Scientific and Technical Information of China (English)

    陈瑞强; 江月松

    2013-01-01

    The performance of pulsed laser ranging is directly influenced by the method how to measure the time-interval. Refer to the idea of interpolation time-interval measurement, the character of triangle reference signal is used to realize measurement on time-interval which has advantages of long measurement range and high precision. The principle how to use triangle reference signal to realize measurement on time-interval is described. The factors that affect the precision of time-interval measurement is quantitatively analyzed. It is pointed out that the frequency of triangle reference signal and the noise attached in triangle reference signal are the two main factors which affect the precision of time-interval measurement. Then, their affect on the precision of time-interval measurement is numerically simulated. A confirmatory experiment is designed to explain how the noise attached in triangle reference signal affects the precision of time-interval measurement. Both the numerical simulation and the experimental result show that the method of measurement on time-interval in pulsed laser ranging which uses low frequency triangle reference signal can achieve high precision. Besides, both improving the frequency of triangle reference signal and reducing the noise attached in triangle reference signal can effectively improve the precision of time-interval measurement. The numerical simulation and experimental results also confirm the feasibility of measurement on time-interval on pulsed laser ranging.%时间间隔测量方法的优劣直接影响脉冲激光测距的性能.借鉴插值法的思想,提出了利用三角波参考信号的特点实现时间间隔测量的方法,具有测量范围大、测量精度高的优点.阐述了利用三角波参考信号实现时间间隔测量的原理,定量分析了影响时间间隔测量精度的因素,指出三角波参考信号的频率和噪声是影响测量精度的主要原因,并进行了数值仿真;设计实验

  16. Boresight calibration of construction misalignments for 3D scanners built with a 2D laser range finder rotating on its optical center.

    Science.gov (United States)

    Morales, Jesús; Martínez, Jorge L; Mandow, Anthony; Reina, Antonio J; Pequeño-Boter, Alejandro; García-Cerezo, Alfonso

    2014-10-24

    Many applications, like mobile robotics, can profit from acquiring dense, wide-ranging and accurate 3D laser data. Off-the-shelf 2D scanners are commonly customized with an extra rotation as a low-cost, lightweight and low-power-demanding solution. Moreover, aligning the extra rotation axis with the optical center allows the 3D device to maintain the same minimum range as the 2D scanner and avoids offsets in computing Cartesian coordinates. The paper proposes a practical procedure to estimate construction misalignments based on a single scan taken from an arbitrary position in an unprepared environment that contains planar surfaces of unknown dimensions. Inherited measurement limitations from low-cost 2D devices prevent the estimation of very small translation misalignments, so the calibration problem reduces to obtaining boresight parameters. The distinctive approach with respect to previous plane-based intrinsic calibration techniques is the iterative maximization of both the flatness and the area of visible planes. Calibration results are presented for a case study. The method is currently being applied as the final stage in the production of a commercial 3D rangefinder.

  17. Active Stand-off Detection of Gas Leaks Using a Short Range Hard-target Backscatter Differential Optical Absorption System Based on a Quantum Cascade Laser Transmitter

    Science.gov (United States)

    Diaz, Adrian; Thomas, Benjamin; Castillo, Paulo; Gross, Barry; Moshary, Fred

    2016-06-01

    Fugitive gas emissions from agricultural or industrial plants and gas pipelines are an important environmental concern as they can contribute to the global increase of greenhouse gas concentration. Moreover, they are also a security and safety concern because of possible risk of fire/explosion or toxicity. This study presents gas concentration measurements using a quantum cascade laser open path system (QCLOPS). The system retrieves the pathaveraged concentration of N2O and CH4 by collecting the backscattered light from a scattering target. The gas concentration measurements have a high temporal resolution (68 ms) and are achieved at sufficient range (up to 40 m, ~ 130 feet) with a detection limit of 2.6 ppm CH4 and 0.4 ppm for N2O. Given these characteristics, this system is promising for mobile/multidirectional remote detection and evaluation of gas leaks. The instrument is monostatic with a tunable QCL emitting at ~ 7.7 μm wavelength range. The backscattered radiation is collected by a Newtonian telescope and focused on an infrared light detector. Puffs of N2O and CH4 are released along the optical path to simulate a gas leak. The measured absorption spectrum is obtained using the thermal intra-pulse frequency chirped DFB QCL and is analyzed to obtain path averaged gas concentrations.

  18. Navigation of an Autonomous Tractor for a Row-Type Tree Plantation Using a Laser Range Finder—Development of a Point-to-Go Algorithm

    Directory of Open Access Journals (Sweden)

    Pawin Thanpattranon

    2015-09-01

    Full Text Available It is challenging to develop a control algorithm that uses only one sensor to guide an autonomous vehicle. The objective of this research was to develop a control algorithm with a single sensor for an autonomous agricultural vehicle that could identify landmarks in the row-type plantation environment and navigate a vehicle to a point-to-go target location through the plantation. To enable such a navigation system for the plantation system, a laser range finder (LRF was used as a single sensor to detect objects and navigate a full-size autonomous agricultural tractor. The LRF was used to control the tractor as it followed a path, and landmarks were detected “on-the-go” in real time. The landmarks were selected based on data for their distances calculated by comparison with the surrounding objects. Once the landmarks were selected, a target point was calculated from the landmarks, and the tractor was navigated toward the target. Navigation experiments were successfully conducted on the selected paths without colliding with the surrounding objects. A real time kinematic global positioning system (RTK GPS was used to compare the positioning between the autonomous control and manual control. The results of this study showed that this control system could navigate the autonomous tractor to follow the paths, and the vehicle position differed from the manually driven paths by 0.264, 0.370 and 0.542 m for the wide, tight, and U-turn paths, respectively, with directional accuracies of 3.139°, 4.394°, and 5.217°, respectively, which are satisfactory for the autonomous operation of tractors on rubber or palm plantations. Therefore, this laser-based landmark detection and navigation system can be adapted to an autonomous navigation system to reduce the vehicle`s sensor cost and improve the accuracy of the positioning.

  19. Header For Laser Diode

    Science.gov (United States)

    Rall, Jonathan A. R.; Spadin, Paul L.

    1990-01-01

    Header designed to contain laser diode. Output combined incoherently with outputs of other laser diodes in grating laser-beam combiner in optical communication system. Provides electrical connections to laser diode, cooling to thermally stabilize laser operation, and optomechanical adjustments that steer and focus laser beam. Range of adjustments provides for correction of worst-case decentering and defocusing of laser beam encountered with laser diodes. Mechanical configuration made simple to promote stability and keep cost low.

  20. A study of SiC decomposition under laser irradiation

    Science.gov (United States)

    Adelmann, B.; Hellmann, R.

    2017-06-01

    In this experimental study we investigate the laser induced thermal decomposition of 4H-Sic under ambient conditions using fiber laser. Using a unique two-color pyrometer setup, we measure the temporal evolution of the temperature in the irradiated zone and determine the decomposition rate for various laser power levels. We find that the temporal evolution of the temperature in the irradiated area exhibits an initial heating phase up to about 1300 K, being characterized by an unaffected SiC surface. Upon an expeditious temperature increase, a decomposition phase follows with temperatures above 1700 K, being accompanied by carbonization of the SiC surface. The decomposed volume depends linearly on the duration of the decomposition phase and increases linearly with laser power. The temperature evaluation of the decomposition speed reveals an Arrhenius-type behavior allowing the calculation of the activation energy for the decomposition under ambient conditions to 613 kJ/mol in the temperature range between 2140 and 2420 K.