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Sample records for chandra transmission grating

  1. Chandra High Energy Transmission Grating Spectrum of AE Aquarii

    CERN Document Server

    Mauche, Christopher W

    2009-01-01

    (Abridged) The results of a Chandra X-ray Observatory High-Energy Transmission Grating (HETG) observation of the nova-like cataclysmic binary AE Aqr are described. First, the X-ray spectrum is that of an optically thin multi-temperature thermal plasma; the X-ray emission lines are broad, with widths that increase with the line energy, from sigma~1 eV for O VIII to sigma~5.5 eV for Si XIV; the X-ray spectrum is reasonably well fit by a plasma model with a Gaussian emission measure distribution that peaks at log T(K)=7.16, has a width sigma=0.48, an Fe abundance equal to 0.44 times solar, and other metal (primarily Ne, Mg, and Si) abundances equal to 0.76 times solar; and for a distance d=100 pc, the total emission measure EM=8.0E53 cm^-3 and the 0.5-10 keV luminosity L_X=1.1E31 erg/s. Second, based on the f/(i+r) flux ratios of the forbidden (f), intercombination (i), and recombination (r) lines of the He alpha triplets of N VI, O VII, and Ne IX measured by Itoh et al. in the XMM-Newton Reflection Grating Spec...

  2. The Chandra High Energy Transmission Grating: Design, Fabrication, Ground Calibration and Five Years in Flight

    CERN Document Server

    Canizares, C R; Dewey, D; Flanagan, K A; Galton, E B; Huenemoerder, D P; Ishibashi, K; Markert, T H; Marshall, H L; McGuirk, M; Schattenburg, M L; Schulz, N S; Smith, H I; Wise, M; Canizares, Claude R.; Davis, John E.; Dewey, Daniel; Flanagan, Kathryn A.; Galton, Eugene B.; Huenemoerder, David P.; Ishibashi, Kazunori; Markert, Thomas H.; Marshall, Herman L.; Guirk, Michael Mc; Schattenburg, Mark L.; Schulz, Norbert S.; Smith, Henry I.; Wise, Michael

    2005-01-01

    Details of the design, fabrication, ground and flight calibration of the High Energy Transmission Grating, HETG, on the Chandra X-ray Observatory are presented after five years of flight experience. Specifics include the theory of phased transmission gratings as applied to the HETG, the Rowland design of the spectrometer, details of the grating fabrication techniques, and the results of ground testing and calibration of the HETG. For nearly six years the HETG has operated essentially as designed, although it has presented some subtle flight calibration effects.

  3. In-Flight Calibration of the Chandra High Energy Transmission Grating Spectrometer

    CERN Document Server

    Marshall, H L; Ishibashi, K; Marshall, Herman L.; Dewey, Daniel; Ishibashi, Kazunori

    2003-01-01

    We present results from in-flight calibration of the High Energy Transmission Grating Spectrometer (HETGS) on the Chandra X-ray Observatory. Basic grating assembly parameters such as orientation and average grating period were measured using emission line sources. These sources were also used to determine the locations of individual CCDs within the flight detector. The line response function (LRF) was modeled in detail using an instrument simulator based on pre-flight measurements of the grating alignments and periods. These LRF predictions agree very well with in-flight observations of sources with narrow emission lines. Using bright continuum sources, we test the consistency of the detector quantum efficiencies by comparing positive orders to negative orders.

  4. The Chandra High Energy Transmission Grating Observation of an X-ray Ionization Cone in Markarian 3

    OpenAIRE

    Sako, Masao; Kahn, Steven M.; Paerels, Frits; Liedahl, Duane A.

    2000-01-01

    We present a preliminary analysis of the first high-resolution X-ray spectrum of a Seyfert 2 galaxy, Mkn 3, obtained with the High Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory. The high-energy spectrum (lambda < 4 Ang) is dominated by reflection of the AGN continuum radiation in a cold optically thick medium and contains bright K-alpha fluorescent lines from iron and silicon, as well as weak, blended lines from sulfur and magnesium. The soft X-ray emission (4...

  5. The Chandra High Energy Transmission Grating Observation of an X-ray Ionization Cone in Markarian 3

    CERN Document Server

    Sako, M; Paerels, F B S; Liedahl, D A; Sako, Masao; Kahn, Steven M.; Paerels, Frits; Liedahl, Duane A.

    2000-01-01

    We present a preliminary analysis of the first high-resolution X-ray spectrum of a Seyfert 2 galaxy, Mkn 3, obtained with the High Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory. The high-energy spectrum (lambda < 4 Ang) is dominated by reflection of the AGN continuum radiation in a cold optically thick medium and contains bright K-alpha fluorescent lines from iron and silicon, as well as weak, blended lines from sulfur and magnesium. The soft X-ray emission (4 < lambda < 23 Ang) is spatially extended along the [O III] ionization cone and shows discrete signatures of emission following recombination and photoexcitation produced in a warm photoionized region. The measured iron L line fluxes indicate that emission from collisionally ionized plasma is almost completely negligible, and does not contribute significantly to the total energy budget of the X-ray emission. We find that significant fractions of the H- and He-like resonance lines, as well as the observed iron L l...

  6. High Resolution Spectroscopy of the X-ray Photoionized Wind in Cygnus X-3 with the Chandra High Energy Transmission Grating Spectrometer

    CERN Document Server

    Paerels, F B S; Sako, M; Liedahl, D A; Brinkman, A C; Van der Meer, R L J; Kaastra, J S; Predehl, P; Paerels, Frits; Cottam, Jean; Sako, Masao; Liedahl, Duane A.

    2000-01-01

    We present a preliminary analysis of the 1--10 keV spectrum of the massiveX-ray binary Cyg X-3, obtained with the High Energy Transmission GratingSpectrometer on the Chandra X-ray Observatory. The source reveals a richlydetailed discrete emission spectrum, with clear signatures ofphotoionization-driven excitation. Among the spectroscopic novelties in the data are the first astrophysicaldetections of a number of He-like 'triplets' (Si, S, Ar) with emission lineratios characteristic of photoionization equilibrium, fully resolved narrowradiative recombination continua of Mg, Si, and S, the presence of the H-likeFe Balmer series, and a clear detection of a ~ 800 km/s large scale velocityfield, as well as a ~1500 km/s FWHM Doppler broadening in the source. Webriefly touch on the implications of these findings for the structure of theWolf-Rayet wind.

  7. Chandra grating spectroscopy of three hot white dwarfs

    OpenAIRE

    Adamczak, J.; Werner, K.; Rauch, T.; Schuh, S.; Drake, J. J.; Kruk, J. W.

    2012-01-01

    Context. High-resolution soft X-ray spectroscopic observations of single hot white dwarfs are scarce. With the Chandra Low-Energy Transmission Grating, we have observed two white dwarfs, one is of spectral type DA (LB1919) and the other is a non-DA of spectral type PG1159 (PG1520+525). The spectra of both stars are analyzed, together with an archival Chandra spectrum of another DA white dwarf (GD246). Aims. The soft X-ray spectra of the two DA white dwarfs are investigated in orde...

  8. Chandra grating spectroscopy of three hot white dwarfs

    CERN Document Server

    Adamczak, J; Rauch, T; Schuh, S; Drake, J J; Kruk, J W

    2012-01-01

    High-resolution soft X-ray spectroscopic observations of single hot white dwarfs are scarce. With the Chandra Low-Energy Transmission Grating, we have observed two white dwarfs, one is of spectral type DA (LB 1919) and the other is a non-DA of spectral type PG1159 (PG 1520+525). The spectra of both stars are analyzed, together with an archival Chandra spectrum of another DA white dwarf (GD 246). The soft X-ray spectra of the two DA white dwarfs are investigated in order to study the effect of gravitational settling and radiative levitation of metals in their photospheres. LB 1919 is of interest because it has a significantly lower metallicity than DAs with otherwise similar atmospheric parameters. GD 246 is the only white dwarf known that shows identifiable individual iron lines in the soft X-ray range. For the PG1159 star, a precise effective temperature determination is performed in order to confine the position of the blue edge of the GW Vir instability region in the HRD. (abridged)

  9. The CHANDRA X-ray Grating Spectrum of Eta Carinae

    CERN Document Server

    Corcoran, M F; Petre, R; Ishibashi, K; Davidson, K; Townsley, L K; Smith, R; White, S; Viotti, R; Damineli, A

    2001-01-01

    Eta Car may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emisssion. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on either side of the colliding wind bow shock, effectively ``resolving'' the shock. The pre-shock wind velocities are ~500 and ~ 2000 km/s in our analysis, and these velocities are interpreted as the terminal velocities of the winds from Eta Car and from the hidden companion star. The abundances of Si and Fe are significantly non-solar based on the strengths of the observed H- and He-like emission lines. The iron fluorescent line at 1.93 Angstrom, first detected by ASCA, is clearly resolved from the thermal iron line in th...

  10. Chandra Grating Spectroscopy of Three Hot White Dwarfs

    Science.gov (United States)

    Adamczak, J.; Werner, K.; Rauch, T.; Schuh, S.; Drake, J. J.; Kruk, J. W.

    2013-01-01

    High-resolution soft X-ray spectroscopic observations of single hot white dwarfs are scarce. With the Chandra Low-Energy Transmission Grating, we have observed two white dwarfs, one is of spectral type DA (LB1919) and the other is a non-DA of spectral type PG1159 (PG1520+525). The spectra of both stars are analyzed, together with an archival Chandra spectrum of another DA white dwarf (GD246). Aims. The soft X-ray spectra of the two DA white dwarfs are investigated in order to study the effect of gravitational settling and radiative levitation of metals in their photospheres. LB1919 is of interest because it has a significantly lower metallicity than DAs with otherwise similar atmospheric parameters. GD246 is the only white dwarf known that shows identifiable individual iron lines in the soft X-ray range. For the PG1159 star, a precise effective temperature determination is performed in order to confine the position of the blue edge of the GW Vir instability region in the HRD. Methods. The Chandra spectra are analyzed with chemically homogeneous as well as stratified NLTE model atmospheres that assume equilibrium between gravitational settling and radiative acceleration of chemical elements. Archival EUV and UV spectra obtained with EUVE, FUSE, and HST are utilized to support the analysis. Results. No metals could be identified in LB1919. All observations are compatible with a pure hydrogen atmosphere. This is in stark contrast to the vast majority of hot DA white dwarfs that exhibit light and heavy metals and to the stratified models that predict significant metal abundances in the atmosphere. For GD246 we find that neither stratified nor homogeneous models can fit the Chandra spectrum. The Chandra spectrum of PG1520+525 constrains the effective temperature to T(sub eff) = 150 000 +/- 10 000 K. Therefore, this nonpulsating star together with the pulsating prototype of the GWVir class (PG1159-035) defines the location of the blue edge of the GWVir instability region

  11. Chandra grating spectroscopy of three hot white dwarfs

    Science.gov (United States)

    Adamczak, J.; Werner, K.; Rauch, T.; Schuh, S.; Drake, J. J.; Kruk, J. W.

    2012-10-01

    Context. High-resolution soft X-ray spectroscopic observations of single hot white dwarfs are scarce. With the Chandra Low-Energy Transmission Grating, we have observed two white dwarfs, one is of spectral type DA (LB 1919) and the other is a non-DA of spectral type PG 1159 (PG 1520+525). The spectra of both stars are analyzed, together with an archival Chandra spectrum of another DA white dwarf (GD 246). Aims: The soft X-ray spectra of the two DA white dwarfs are investigated in order to study the effect of gravitational settling and radiative levitation of metals in their photospheres. LB 1919 is of interest because it has a significantly lower metallicity than DAs with otherwise similar atmospheric parameters. GD 246 is the only white dwarf known that shows identifiable individual iron lines in the soft X-ray range. For the PG 1159 star, a precise effective temperature determination is performed in order to confine the position of the blue edge of the GW Vir instability region in the HRD. Methods: The Chandra spectra are analyzed with chemically homogeneous as well as stratified NLTE model atmospheres that assume equilibrium between gravitational settling and radiative acceleration of chemical elements. Archival EUV and UV spectra obtained with EUVE, FUSE, and HST are utilized to support the analysis. Results: No metals could be identified in LB 1919. All observations are compatible with a pure hydrogen atmosphere. This is in stark contrast to the vast majority of hot DA white dwarfs that exhibit light and heavy metals and to the stratified models that predict significant metal abundances in the atmosphere. For GD 246 we find that neither stratified nor homogeneous models can fit the Chandra spectrum. The Chandra spectrum of PG 1520+525 constrains the effective temperature to Teff = 150 000 ± 10 000 K. Therefore, this nonpulsating star together with the pulsating prototype of the GW Vir class (PG 1159 - 035) defines the location of the blue edge of the GW Vir

  12. The CHANDRA HETGS X-ray Grating Spectrum of Eta Carinae

    Science.gov (United States)

    Corcoran, M. F.; Swank, J. H.; Petre, R.; Ishibashi, K.; Davidson, K.; Townsley, L.; Smith, R.; White, S.; Viotti, R.; Damineli, A.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    Eta Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emission. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on either side of the colliding wind bow shock, effectively 'resolving' the shock. If so, the pre-shock wind velocities are approximately 700 and 1800 km/s in our analysis, and these velocities may be interpreted as the terminal velocities of the winds from 71 Carinae and from the hidden companion star. The forbidden-to-intercombination line ratios for the He-like ions of S, Si, and Fe are large, indicating that the line forming region lies far from the stellar photosphere. The iron fluorescent line at 1.93 angstroms, first detected by ASCA, is clearly resolved from the thermal iron line in the CHANDRA grating spectrum. The Fe fluorescent line is weaker in our CHANDRA observation than in any of the ASCA spectra. The CHANDRA observation also provides the first high-time resolution lightcurve of the uncontaminated stellar X-ray emission from 77 Carinae and shows that there is no significant, coherent variability during the CHANDRA observation. The 77 Carinae CHANDRA grating spectrum is unlike recently published X-ray grating spectra of single massive stars in significant ways and is generally consistent with colliding wind emission in a massive binary.

  13. The CHANDRA HETGS X-ray Grating Spectrum of Eta Car

    OpenAIRE

    Corcoran, M. F; Swank, J.H.; Petre, R.; Ishibashi, K.; Davidson, K.; Townsley, L.; Smith, R.; S. White; Viotti, R; A. Damineli

    2001-01-01

    Eta Car may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emisssion. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on...

  14. The Chandra High Energy Transmission Grating Spectrometer probes the dusty warm absorber in the Seyfert 1 galaxy MCG--6-30-15

    OpenAIRE

    Lee, J. C.; Canizares, C. R.; Marshall, H. L.; Fabian, A. C.; Morales, R.; Schulz, N. S.; Iwasawa, K.

    2001-01-01

    The Chandra HETGS spectra of the Seyfert 1 galaxy MCG--6-30-15 show numerous narrow, unresolved (FWHM 0.48 keV (< 26 A). We attribute previous reports of an apparently highly redshifted O VII edge to the neutral Fe L absorption complex and th...

  15. Characterization of pinhole transmission gratings.

    Science.gov (United States)

    Eidmann, K; Kühne, M; Müller, P; Tsakiris, G D

    1990-01-01

    Gold pinhole transmission gratings fabricated by Heidenhain GmbH primarily for the purpose of studying the radiation of intense soft x-ray sources have been tested with the synchrotron radiation of BESSY. Typical results for the spectral dependence of the grating efficiency into the various diffraction orders are presented in a wavelength region ranging from 4 to 20 nm. Also the influence of grating irregularities has been studied. With appropriate grating parameters quite good agreement between the experimental results and theoretical Calculations is Obtained. PMID:21307429

  16. The Chandra High Energy Transmission Grating Spectrometer probes the dusty warm absorber in the Seyfert 1 galaxy MCG--6-30-15

    CERN Document Server

    Lee, J C; Marshall, H L; Fabian, A C; Morales, R; Schulz, N S; Iwasawa, K

    2001-01-01

    The Chandra HETGS spectra of the Seyfert 1 galaxy MCG--6-30-15 show numerous narrow, unresolved (FWHM 0.48 keV (< 26 A). We attribute previous reports of an apparently highly redshifted O VII edge to the neutral Fe L absorption complex and the O VII resonance series (by transitions higher than He $\\gamma$; He $\\alpha,\\beta,\\gamma$ are also seen at lower energies). The implied dust column density needed to explain the FeI L edge feature agrees with that obtained from earlier reddening studies, which had already concluded that the dust should be associated with the ionized absorber (given the relatively lower observed X-ray absorption by cold gas). Our findings contradict the interpretation of Branduardi-Raymont et al. (2001), based on XMM-Newton RGS spectra, that this spectral region is dominated by highly relativistic soft X-ray line emission originating near the central black hole. Here we review these issues pertaining to the soft X-ray spectral features as addressed by Lee et al., (2001). (Details foun...

  17. Fabrication update on critical-angle transmission gratings for soft x-ray grating spectrometers

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alex; Mukherjee, Pran; Yam, Jonathan; Schattenburg, Mark L.

    2011-09-01

    Diffraction grating-based, wavelength dispersive high-resolution soft x-ray spectroscopy of celestial sources promises to reveal crucial data for the study of the Warm-Hot Intergalactic Medium, the Interstellar Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, and other areas of interest to the astrophysics community. Our recently developed critical-angle transmission (CAT) gratings combine the advantages of the Chandra high and medium energy transmission gratings (low mass, high tolerance of misalignments and figure errors, polarization insensitivity) with those of blazed reflection gratings (high broad band diffraction efficiency, high resolution through use of higher diffraction orders) such as the ones on XMM-Newton. Extensive instrument and system configuration studies have shown that a CAT grating-based spectrometer is an outstanding instrument capable of delivering resolving power on the order of 5,000 and high effective area, even with a telescope point-spread function on the order of many arc-seconds. We have fabricated freestanding, ultra-high aspect-ratio CAT grating bars from silicon-on-insulator wafers using both wet and dry etch processes. The 200 nm-period grating bars are supported by an integrated Level 1 support mesh, and a coarser external Level 2 support mesh. The resulting grating membrane is mounted to a frame, resulting in a grating facet. Many such facets comprise a grating array that provides light-weight coverage of large-area telescope apertures. Here we present fabrication results on the integration of CAT gratings and the different high-throughput support mesh levels and on membrane-frame bonding. We also summarize recent x-ray data analysis of 3 and 6 micron deep wet-etched CAT grating prototypes.

  18. The Kinematics and Physical Conditions of the Ionized Gas in NGC 4593 from Chandra High-Energy Grating Spectroscopy

    CERN Document Server

    McKernan, B; George, I M; Turner, T J

    2003-01-01

    We observed the Seyfert 1 galaxy NGC 4593 with the Chandra high energy transmission gratings and present a detailed analysis of the soft X-ray spectrum. We measure strong absorption lines from He-like O, Ne, Mg, Si, H-like N, O, Ne, Mg, Si and highly ionized Fe XIX-XXV. Only the NLya, OLya and MgLya lines appear to be marginally resolved. We identify a spectral feature at $\\sim 0.707$ keV with a neutral Fe L edge, which might suggest that there is dust along the line-of-sight to \

  19. Efficient EUV transmission gratings for plasma diagnostics

    Science.gov (United States)

    Braig, Christoph; Kley, Ernst-Bernhard

    2010-07-01

    We report on a theoretical study of binary phase transmission gratings for high-resolution EUV and soft X-ray spectroscopy and investigate their optical properties. Designed for wavelengths between about 2 and 40 nm, the devices may provide a first order diffraction efficiency beyond 30%. We use RCWA methods in order to optimize the grating design parameters and discuss special features of segmented grating arrays. Several elemental as well as compound materials like Be, Mo, LiF and PMMA are considered with respect to their potential and practical limitations in terms of feasibility and sensitivity to radiation damage. Simulations are performed for several samples on the radiation produced by a table-top EUV plasma source and applications to astrophysical problems are considered.

  20. Plasmonic Transmission Gratings – Fabrication and Characterization

    DEFF Research Database (Denmark)

    Sierant, Aleksandra; Jany, Benedykt; Bartoszek-Bober, Dobrosława;

    realization is given by the use of a metallic diffraction grating, where the diffracted light couples to the SPP. Here, we propose metallic periodic transmission gratings, processed onto a glass substrate, with various periods and fill factors. The gratings are milled in a plain gold layer with a focused ion......Surface plasmon polaritons (SPPs) are collective electron oscillations, confined at metal-dielectric interfaces. Coupling incident photons to SPPs may lead to spectrally broad field enhancement and confinement below the diffraction limit [1]. This phenomenon facilitates various applications......) Simulations. [1] W. L. Barnes, A. Dereux, T. W. Ebbesen, Nature 424, 824–830 (2003) [2] X. D. Hoa, A. G. Kirk, M. Tabrizian, Biosensors and Bioelectronics, 23, 2, 151-160 (2007) [3] T. Kawalec, et al., Opt. Lett. 39, 2932 (2014)...

  1. Advanced experimental applications for x-ray transmission gratings Spectroscopy using a novel grating fabrication method

    OpenAIRE

    Hurvitz, G.; Ehrlich, Y.; Strum, G.; Shpilman, Z.; Levy, I.; Fraenkel, M.

    2012-01-01

    A novel fabrication method for soft x-ray transmission grating and other optical elements is presented. The method uses Focused-Ion-Beam (FIB) technology to fabricate high-quality free standing grating bars on Transmission Electron Microscopy grids (TEM-grid). High quality transmission gratings are obtained with superb accuracy and versatility. Using these gratings and back-illuminated CCD camera, absolutely calibrated x-ray spectra can be acquired for soft x-ray source diagnostics in the 100...

  2. Fabrication of large-area and low mass critical-angle x-ray transmission gratings

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alex R.; Guan, Dong; Schattenburg, Mark L.

    2014-07-01

    Soft x-ray spectroscopy of celestial sources with high resolving power R = E/ΔE and large collecting area addresses important science listed in the Astro2010 Decadal Survey New Worlds New Horizons, such as the growth of the large scale structure of the universe and its interaction with active galactic nuclei, the kinematics of galactic outflows, as well as coronal emission from stars and other topics. Numerous studies have shown that a transmission grating spectrometer based on lightweight critical-angle transmission (CAT) gratings can deliver R = 3000-5000 and large collecting area with high efficiency and minimal resource requirements, providing spectroscopic figures of merit at least an order of magnitude better than grating spectrometers on Chandra and XMM-Newton, as well as future calorimeter-based missions. The recently developed CAT gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Their working principle based on blazing through reflection off the smooth, ultra-high aspect ratio grating bar sidewalls has previously been demonstrated on small samples with x rays. For larger gratings (area greater than 1 inch square) we developed a fabrication process for grating membranes with a hierarchy of integrated low-obscuration supports. The fabrication involves a combination of advanced lithography and highly anisotropic dry and wet etching techniques. We report on the latest fabrication results of free-standing, large-area CAT gratings with polished sidewalls and preliminary x-ray tests.

  3. High-efficiency blazed transmission gratings for high-resolution soft x-ray spectroscopy

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alexander R.; Schattenburg, Mark L.

    2015-09-01

    High-resolution spectroscopy of astrophysical sources is the key to gaining a quantitative understanding of the history, dynamics, and current conditions of the cosmos. A large-area (> 1,000 cm2), high resolving power (R = λ/Δλ> 3000) soft x-ray grating spectrometer (XGS) that covers the lines of C, N, O, Ne and Fe ions is the ideal tool to address a number of high-priority science questions from the 2010 Decadal Survey, such as the connection between super-massive black holes and large-scale structure via cosmic feedback, the evolution of large- scale structure, the behavior of matter at high densities, and the conditions close to black holes. While no grating missions or instruments are currently approved, an XGS aboard a potential future X-ray Surveyor could easily surpass the above performance metrics. To improve the chances for future soft x-ray grating spectroscopy missions or instruments, grating technology has to progress and advance to higher Technology Readiness Levels (TRLs). To that end we have developed Critical-Angle Transmission (CAT) gratings that combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of conventional transmission gratings (low mass, relaxed alignment tolerances and temperature requirements, high transparency at higher energies). A CAT grating-based spectrometer can provide performance 1-2 orders of magnitude better than current grating instruments on Chandra and Newton-XMM with minimal resource requirements. At present we have fabricated large-area freestanding CAT gratings with narrow integrated support structures from silicon-on- insulator wafers using advanced lithography and a combination of deep reactive-ion and wet etching. Our latest x-ray test results show record high absolute diffraction efficiencies in blazed orders in excess of 30% with room for improvement.

  4. Advanced experimental applications for x-ray transmission gratings Spectroscopy using a novel grating fabrication method

    CERN Document Server

    Hurvitz, G; Strum, G; Shpilman, Z; Levy, I; Fraenkel, M

    2012-01-01

    A novel fabrication method for soft x-ray transmission grating and other optical elements is presented. The method uses Focused-Ion-Beam (FIB) technology to fabricate high-quality free standing grating bars on Transmission Electron Microscopy grids (TEM-grid). High quality transmission gratings are obtained with superb accuracy and versatility. Using these gratings and back-illuminated CCD camera, absolutely calibrated x-ray spectra can be acquired for soft x-ray source diagnostics in the 100-3000 eV spectral range. Double grating combinations of identical or different parameters are easily fabricated, allowing advanced one-shot application of transmission grating spectroscopy. These applications include spectroscopy with different spectral resolutions, bandwidths, dynamic ranges, and may serve for identification of high-order contribution, and spectral calibrations of various x-ray optical elements.

  5. Advanced experimental applications for x-ray transmission gratings spectroscopy using a novel grating fabrication method

    Science.gov (United States)

    Hurvitz, G.; Ehrlich, Y.; Strum, G.; Shpilman, Z.; Levy, I.; Fraenkel, M.

    2012-08-01

    A novel fabrication method for soft x-ray transmission grating and other optical elements is presented. The method uses focused-ion-beam technology to fabricate high-quality free standing grating bars on transmission electron microscopy grids. High quality transmission gratings are obtained with superb accuracy and versatility. Using these gratings and back-illuminated CCD camera, absolutely calibrated x-ray spectra can be acquired for soft x-ray source diagnostics in the 100-3000 eV spectral range. Double grating combinations of identical or different parameters are easily fabricated, allowing advanced one-shot application of transmission grating spectroscopy. These applications include spectroscopy with different spectral resolutions, bandwidths, dynamic ranges, and may serve for identification of high-order contribution, and spectral calibrations of various x-ray optical elements.

  6. Enhanced acoustic transmission through a slanted grating

    CERN Document Server

    Norris, Andrew N

    2015-01-01

    It is known that an acoustic wave incident on an infinite array of aligned rectangular blocks of a different acoustic material exhibits total transmission if certain conditions are met [1] which relate the unique "intromission" angle of incidence with geometric and material properties of the slab. This extraordinary acoustic transmission phenomenon holds for any slab thickness, making it analogous to a Brewster effect in optics, and is independent of frequency as long as the slab microstructure is sub-wavelength in the length-wise direction. Here we show that the enhanced transmission effect is obtained in a slab with grating elements oriented obliquely to the slab normal. The dependence of the intromission angle $\\theta_i$ is given explicitly in terms of the orientation angle. Total transmission is achieved at incidence angles $\\pm \\theta_i$, with a relative phase shift between the transmitted amplitudes of the $+\\theta_i$ and $- \\theta_i$ cases. These effects are shown to follow from explicit formulas for t...

  7. Topology-optimized broadband surface relief transmission grating

    DEFF Research Database (Denmark)

    Andkjær, Jacob; Ryder, Christian P.; Nielsen, Peter C.;

    2014-01-01

    We propose a design methodology for systematic design of surface relief transmission gratings with optimized diffraction efficiency. The methodology is based on a gradient-based topology optimization formulation along with 2D frequency domain finite element simulations for TE and TM polarized plane...... waves. The goal of the optimization is to find a grating design that maximizes diffraction efficiency for the -1st transmission order when illuminated by unpolarized plane waves. Results indicate that a surface relief transmission grating can be designed with a diffraction efficiency of more than 40...

  8. Critical-angle Transmission Grating Development for AXSIO

    Science.gov (United States)

    Bautz, Mark W.; Heilmann, R. K.; Schattenburg, M.; Marshall, H. L.; Huenemoerder, D.; Dewey, D.; Schulz, N. S.; Davis, J. E.

    2013-04-01

    Large area, high resolving power spectroscopy in the soft x-ray band can at present only be achieved with a state-of-the-art diffraction grating spectrometer. Recently developed critical-angle transmission (CAT) gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Several new mission concepts containing CAT grating based spectrometers such as AXSIO promise to deliver unprecedented order-of-magnitude improvements in soft x-ray spectroscopy figures of merit. The CAT grating principle has previously been demonstrated with x rays using small wet-etched samples. We report the latest progress in the fabrication and testing of large (32x32 mm2) CAT grating prototypes with an integrated hierarchy of low-obstruction support structures. The gratings are fabricated from silicon-on-insulator wafers using advanced lithography and highly anisotropic dry and wet etching techniques. We present our latest grating fabrication results.

  9. Colossal optical transmission through buried metal gratings (Presentation Recording)

    Science.gov (United States)

    Roberts, Christopher M.; Liu, Runyu; Zhao, Xiang; Yu, Lan; Li, Xiuling; Wasserman, Daniel M.; Podolskiy, Viktor A.

    2015-09-01

    In Extraordinary Optical Transmission (EOT), a metallic film perforated with an array of [periodic] apertures exhibits transmission over 100% normalized to the total aperture area, at selected frequencies. EOT devices have potential applications as optical filters and as couplers in hybrid electro-optic contacts/devices. Traditional passive extraordinary optical transmission structures, typically demonstrate un-normalized transmission well below 50%, and are typically outperformed by simpler thin-film techniques. To overcome these limitations, we demonstrate a new breed of extraordinary optical transmission devices, by "burying" an extraordinary optical transmission grating in a dielectric matrix via a metal-assisted-chemical etching process. The resulting structure is an extraordinary optical transmission grating on top of a dielectric substrate with dielectric nano-pillars extruded through the grating apertures. These structures not only show significantly enhanced peak transmission when normalized to the open area of the metal film, but more importantly, peak transmission greater than that observed from the bare semiconductor surface. The structures were modeled using three-dimensional rigorous coupled wave analysis and characterized experimentally by Fourier transform infrared reflection and transmission spectroscopy, and the good agreement between the two has been demonstrated. The drastic enhancement of light transmission in our structures originates from structuring of high-index dielectric substrate, with pillars effectively guiding light through metal apertures.

  10. Broadband enhanced transmission of acoustic waves through serrated metal gratings

    Science.gov (United States)

    Qi, Dong-Xiang; Fan, Ren-Hao; Deng, Yu-Qiang; Peng, Ru-Wen; Wang, Mu; Jiangnan University Collaboration

    In this talk, we present our studies on broadband properties of acoustic waves through metal gratings. We have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the acoustic transmission properties of metal gratings with or without serrated boundaries. The average transmission is obviously enhanced for serrated metal gratings within a wide frequency range, while the Fabry-Perot resonance is significantly suppressed. An effective medium hypothesis with varying acoustic impedance is proposed to analyze the mechanism, which was verified through comparison with finite-element simulation. The serrated boundary supplies gradient mass distribution and gradient normal acoustic impedance, which could efficiently reduce the boundary reflection. Further, by increasing the region of the serrated boundary, we present a broadband high-transmission grating for wide range of incident angle. Our results may have potential applications to broadband acoustic imaging, acoustic sensing and new acoustic devices. References: [1] Dong-Xiang Qi, Yu-Qiang Deng, Di-Hu Xu, Ren-Hao Fan, Ru-Wen Peng, Ze-Guo Chen, Ming-Hui Lu, X. R. Huang and Mu Wang, Appl. Phys. Lett. 106, 011906 (2015); [2] Dong-Xiang Qi, Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Ming-Hui Lu, Xu Ni, Qing Hu, and Mu Wang, Applied Physics Letters 101, 061912 (2012).

  11. Critical-angle transmission grating spectrometer for high-resolution soft x-ray spectroscopy on the International X-ray Observatory

    Science.gov (United States)

    Heilmann, Ralf K.; Davis, John E.; Dewey, Daniel; Bautz, Mark W.; Foster, Rick; Bruccoleri, Alex; Mukherjee, Pran; Robinson, David; Huenemoerder, David P.; Marshall, Herman L.; Schattenburg, Mark L.; Schulz, Norbert S.; Guo, L. Jay; Kaplan, Alex F.; Schweikart, Russell B.

    2010-07-01

    High-resolution spectroscopy at energies below 1 keV covers the lines of C, N, O, Ne and Fe ions, and is central to studies of the Interstellar Medium, the Warm Hot Intergalactic Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, etc. The large collecting area, long focal length, and 5 arcsecond half power diameter telescope point-spread function of the International X-ray Observatory will present unprecedented opportunity for a grating spectrometer to address these areas at the forefront of astronomy and astrophysics. We present the current status of a transmission grating spectrometer based on recently developed high-efficiency critical-angle transmission (CAT) gratings that combine the traditional advantages of blazed reflection and transmission gratings. The optical design places light-weight grating arrays close to the telescope mirrors, which maximizes dispersion distance and thus spectral resolution and minimizes demands on mirror performance. It merges features from the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer, and provides resolving power R = E/ΔE = 3000 - 5000 (full width half max) and effective area >1000 cm2 in the soft x-ray band. We discuss recent results on ray-tracing and optimization of the optical design, instrument configuration studies, and grating fabrication.

  12. Nanofabrication advances for high efficiency critical-angle transmission gratings

    Science.gov (United States)

    Bruccoleri, Alexander R.; Guan, Dong; Heilmann, Ralf K.; Vargo, Steve; DiPiazza, Frank; Schattenburg, Mark L.

    2013-09-01

    We report several break-through nanofabrication developments enabling high efficiency and high resolving power spectrometers in the soft x-ray band. The device is the critical-angle transmission (CAT) grating, which combines the low mass and relaxed alignment tolerances of a transmission grating with the high broad-band efficiency and high diffraction orders of a blazed reflection grating. Past work successfully demonstrated the CAT grating concept; however, the open-area fraction was often less than 20% whilst more than 50% is desired. This presents numerous nanofabrication challenges including a requirement for a freestanding silicon membrane of ultra high-aspect ratio bars at a period of 200 nanometers with minimal cross support blockage. Furthermore, the sidewalls must be smooth to a few nanometers to efficiently reflect soft x-rays. We have developed a complete nanofabrication process for creating freestanding CAT gratings via plasma-etching silicon wafers with a buried layer of SiO2. This removable buried layer enables combining a record-performance plasma etch for the CAT grating with a millimeter-scale honeycomb structural support to create a large-area freestanding membrane. We have also developed a process for polishing sidewalls of plasma-etched ultra-high aspect ratio nanoscale silicon structures via potassium hydroxide (KOH). This process utilizes the anisotropic etch nature of single crystal silicon in KOH. We developed a novel alignment technique to align the CAT grating bars to the {111} planes of silicon within 0.2 degrees, which enables KOH to etch away sidewall roughness without destroying the structure, since the {111} planes etch approximately 100 times slower than the non-{111} planes. Preliminary results of a combined freestanding grating with polishing are presented to enable efficient diffraction of soft x-rays.

  13. Progress in the development of critical-angle transmission gratings

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alex R.; Mukherjee, Pran; Schattenburg, Mark L.

    2012-09-01

    Recently developed Critical-Angle Transmission (CAT) grating technology - in combination with x-ray CCD cameras and large collecting-area focusing optics - will enable a new generation of soft x-ray spectrometers with unprecedented resolving power and effective area and with at least an order of magnitude improvement in figures-of-merit for emission and absorption line detection. This technology will be essential to address a number of high-priority questions identified in the Astro2010 Decadal Survey “New Worlds New Horizons” and open the door to a new discovery space. CAT gratings combine the advantages of soft x-ray transmission gratings (low mass, relaxed figure and alignment tolerances, transparent at high energies) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders to increase resolving power). We report on progress in the fabrication of large-area (31× 31 mm2) free-standing gratings with two levels of low-blockage support structures using highly anisotropic deep reactive-ion etching.

  14. Optimization of top polymer gratings to improve GaN LEDs light transmission

    Institute of Scientific and Technical Information of China (English)

    Xiaomin Jin; Bei Zhang; Tao Dai; Wei Wei; Xiangning; Guoyi Zhang; Simeon Trieu; Fei Wang

    2008-01-01

    @@ We present a grating model of two-dimensional (2D) rigorous coupled wave analysis (RCWA) to study top diffraction gratings on light-emitting diodes(LEDs). We compare the integrated-transmission of the non-grating,rectangular-grating,and triangular-grating cases for the same grating period of 6μm,and show that the triangular grating has the best performance. For the triangular grating with 6-μmperiod, the LED achieves the highest light transmission at 6-μ gratingbottom width and 2.9-μm grating depth. Compared with the non-grating case, the optimized light transmission improvement is about 74.6%.The simulation agrees with the experimental data of the thin ploymer grating encapsulated flip-chip(FC) GaN-based LEDs for the light extraction improvement.

  15. Efficient extreme ultraviolet transmission gratings for plasma diagnostics

    Science.gov (United States)

    Braig, Christoph; Predehl, Peter; Kley, Ernst-Bernhard

    2011-06-01

    We report on a theoretical study of free-standing phase transmission gratings for high-resolution extreme ultraviolet (EUV) and soft x-ray spectroscopy and investigate their properties. Designed for wavelengths between about 2 and 40 nm, the devices may provide a first order diffraction efficiency beyond 30%. We use rigorous coupled wave analysis methods in order to optimize the grating design parameters and discuss features of segmented grating arrays. Elemental, as well as compound, materials such as Be, Mo, LiF, and poly-(methylmethacrylate) are considered with respect to their potential and practical limitations in terms of feasibility and sensitivity to radiation damage. Simulations are performed for several samples on the radiation produced by a table-top EUV plasma source and applications to astrophysical problems are considered.

  16. Modeling the NeIX Triplet Spectral Region of Capella with the Chandra and XMM-Newton Gratings

    CERN Document Server

    Ness, J U

    2003-01-01

    High resolution X-ray spectroscopy with the diffraction gratings of Chandra and XMM-Newton offers new chances to study a large variety of stellar coronal phenomena. A popular X-ray calibration target is Capella, which has been observed with all gratings with significant exposure times. We gathered together all available data of the HETGS (155ks), LETGS (219ks), and RGS (53ks) for comparative analysis focusing on the NeIX triplet at around 13.5A, a region that is severely blended by strong iron lines. We identify 18 emission lines in this region of the HEG spectrum, including many from FeXIX, and find good agreement with predictions from a theoretical model constructed using the Astrophysical Plasma Emission Code (APEC). The model uses an emission measure distribution derived from FeXV to FeXXIV lines. While these 18 emission lines cannot be isolated in the LETGS or RGS spectra, their wavelengths and fluxes as measured with HEG are consistent with the lower resolution spectra. In the Capella model for HEG, the...

  17. The nature of transmission resonances in plasmonic metallic gratings

    CERN Document Server

    D'Aguanno, G; Bloemer, M J; de Ceglia, D; Vincenti, M A; Alu', A

    2010-01-01

    Using the Fourier modal method (FMM) we report our analysis of the transmission resonances of a plasmonic grating with sub-wavelength period and extremely narrow slits for wavelengths of the incoming, transverse magnetic (TM)-polarized, radiation ranging from 240nm to 1500nm and incident angles from 0 degree to 90 degree. In particular, we study the case of a silver grating placed in vacuo. Consistent with previous studies on the topic, we highlight that the main mechanism for extraordinary transmission is a TM-Fabry-Perot (FP) branch supported by waveguide modes inside each slit. The TM-FP branch may also interact with surface plasmons (SPs) at the air/Ag interface through the reciprocal lattice vectors of the grating, for periods comparable with the incoming wavelength. When the TM-FP branch crosses a SP branch, a band gap is formed along the line of the SP dispersion. The gap has a Fano-Feshbach resonance at the low frequency band edge and a ridge resonance with extremely long lifetime at the high frequenc...

  18. Application of the Transmission Bragg Gratings for Vibration Monitoring

    CERN Document Server

    Tikhonov, E A

    2010-01-01

    It is shown that the optical-electronic system consisted of the transmission Bragg grating, a laser and the intermediate sensitive to the vibrations mirror can detect the vibrations, when touched by them laser beam scan will exceed the angular divergence of the beam. The mathematical model of the sensor of the vibrations presented in the form of Taylor series describes the system response taking into account the operating point, in particular, describes the effect of the doubling of the modulation frequency response relative to the frequency of acting vibrations.

  19. Study of transmission grating diffraction efficiencies for soft X—ray

    Institute of Scientific and Technical Information of China (English)

    YANGJiamin; CUIMingqi; 等

    1999-01-01

    Tansmission grating spectrometers are extensively used to measure absolute X-ray spectra in a photon-energy range below 1000eV.the transmission grating,as its dispersive element,must be calibrated to obtain its diffraction efficiencies.Calibrations of absolute diffraction efficiencies of the transmission grating at photon energy of 844eV have been caried out on Bejing synchrotron Radiation Facility.With the aid of grating model,all of the grating structure parameters have been determined and the absolute diffraction efficeencies in a photon-energy range below 2000eV have also been calculated and discussed.

  20. Transmission-grating spectrometer for highly efficient and high-resolution soft X-ray emission studies

    Energy Technology Data Exchange (ETDEWEB)

    Yamane, Hiroyuki [Institute for Molecular Science and The Graduate University for Advanced Studies, Okazaki 444-8585 (Japan); Kosugi, Nobuhiro, E-mail: kosugi@ims.ac.jp [Institute for Molecular Science and The Graduate University for Advanced Studies, Okazaki 444-8585 (Japan); Hatsui, Takaki, E-mail: hatsui@spring8.or.jp [RIKEN SPring-8 Center, RIKEN, Hyogo 679-5148 (Japan)

    2013-06-15

    Highlights: ► We develop a highly efficient and high-resolution soft X-ray emission spectrometer. ► We combine a transmission grating, a Wolter type I mirror, and normal-incident CCD. ► X-ray emission resolution proves to be 15–34 meV in the photon energy of 60–100 eV. -- Abstract: A high-resolution soft X-ray emission spectrometer has been developed for site-specific electronic structure analysis of functional materials in the photon energy range of 50–600 eV on the in-vacuum undulator beamline BL3U of the UVSOR facility. In order to realize the high detection efficiency without sacrificing the energy resolution to the signal intensity, the present X-ray emission spectrometer adopts an optical design, which was originally adopted in the field of astrophysics such as Chandra X-ray observatory. This new-type X-ray emission spectrometer consists of a Wolter type I mirror, a freestanding transmission grating, and a charge coupled device (CCD) detector, allowing the focusing with 20 times larger acceptance angle (1.5 × 10{sup −3} sr) than commercially available compact spectrometers with reflection-type gratings such as VG-SCIENTA XES350. The X-ray emission energy resolution of 15–34 meV has successfully been achieved in the photon energy of 60–100 eV by using a transmission grating with the groove density of 5555 lines/mm.

  1. Theoretical models of diffraction efficiencies of arc profiled bar transmission grating

    Science.gov (United States)

    Shang, Wanli; Mei, Lusheng; Yang, Jiamin

    2012-06-01

    Diffraction efficiencies of transmission grating play important roles in accurate measurement of soft X-ray and grating applications. Circular, horizontal elliptical, and vertical elliptical arc profiled bar models were established from Kirchhoff diffraction theory with the Fraunhofer diffraction approximation to calculate the diffraction efficiencies of arc profiled bar transmission grating. The calculated results were compared with the available data from X-ray Optics web site of Lawrence Berkeley Laboratory's Center. Excellent agreements have been obtained. With these modes the diffraction efficiencies of the particular type of transmission grating having arc profiled bars can be simulated accurately and the best fit bar profiles can be obtained.

  2. Spectrophotometry with a transmission grating for detecting faint occultations

    CERN Document Server

    Kenworthy, M A

    2002-01-01

    High-precision spectrophotometry is highly desirable in detecting and characterizing close-in extrasolar planets to learn about their makeup and temperature. For such a goal, a modest-size telescope with a simple low-resolution spectroscopic instrument is potentially as good or better than a complex general purpose spectrograph since calibration and removal of systematic errors is expected to dominate. We use a transmission grating placed in front of an imaging CCD camera on Steward Observatory's Kuiper 1.5 m telescope to provide a high signal-to-noise, low dispersion visible spectrum of the star HD 209458. We attempt to detect the reflected light signal from the extra-solar planet HD 209458b by differencing the signal just before and after secondary occultation. We present a simple data reduction method and explore the limits of ground based low-dispersion spectrophotometry with a diffraction grating. Reflected light detection levels of 0.1% are achievable for 5000-7000A, too coarse for useful limits on ESPs...

  3. Diffraction pattern of self-supporting transmission gratings.

    Science.gov (United States)

    Meekins, J F

    1989-03-15

    Self-supporting transmission gratings suitable for the soft x-ray and extreme ultraviolet must be reinforced by support structures which, if regularly placed, tend to produce undesirable artifacts in the diffraction plane. Because these artifacts appear in the neighborhood of the principal maxima and can be substantial in magnitude, they may confuse the spectrum. Methods are described whereby these unwanted diffraction effects are much reduced or eliminated. In one method, the members of the support structure parallel to the grating slits are placed in a random pattern so that on the average the coherence of the support structure is drastically reduced everywhere. In a second method, these support structure members are distributed pseudorandomly in such a manner that the diffraction pattern of the support structure is completely removed from the diffraction plane. A third method is investigated in which the pseudorandom placement of supports is organized into a repeated pattern, which may be easier to manufacture than the configurations of the first two methods. PMID:20548643

  4. Elimination of higher-order diffraction using zigzag transmission grating in soft x-ray region

    Science.gov (United States)

    Zang, H. P.; Wang, C. K.; Gao, Y. L.; Zhou, W. M.; Kuang, L. Y.; Wei, L.; Fan, W.; Zhang, W. H.; Zhao, Z. Q.; Cao, L. F.; Gu, Y. Q.; Zhang, B. H.; Jiang, G.; Zhu, X. L.; Xie, C. Q.; Zhao, Y. D.; Cui, M. Q.

    2012-03-01

    We present a realization of the sinusoidal transmission function using a series of zigzag-profiled strips where the transmission takes on the binary values 0 and 1 in a two-dimensional distribution. A zigzag transmission grating of 1000 line/mm has been fabricated and demonstrated on the soft x-ray beam of synchrotron radiation. The axial single-order diffraction indicates that the zigzag transmission grating is adequate for spectroscopic application.

  5. Asymmetric transmission of surface plasmon polaritons on planar gratings

    CERN Document Server

    Kuzmiak, Vladimir

    2016-01-01

    We describe a surface structure consisting of a metal-air interface where the metallic part consists of two metallic segments with a periodic modulation of the interface between them. Such a structure possesses a different transmissivity for a surface plasmon polariton incident on it from one side of it than it has for a surface plasmon polariton incident on it from the opposite side. This asymmetric transmission of a surface plasmon polariton is based on the suppression of the zero-order Bragg beam which, for a certain value of the modulation depth, is not transmitted through the structure, while the diffraction efficiencies of the +1 and -1 Bragg beams can be modified by varying the period of grating and/or the angle of incidence. For a certain range of the incidence angle one can observe asymmetry in transmittance for the -1 mode while the +1 mode is completely suppressed. By varying the material and geometrical parameters of the diffractive structure one can control the contrast transmission that characte...

  6. Imaging of Volume Phase Gratings in a Photosensitive Polymer, Recorded in Transmission and Reflection Geometry

    Directory of Open Access Journals (Sweden)

    Tina Sabel

    2014-02-01

    Full Text Available Volume phase gratings, recorded in a photosensitive polymer by two-beam interference exposure, are studied by means of optical microscopy. Transmission gratings and reflection gratings, with periods in the order of 10 μm down to 130 nm, were investigated. Mapping of holograms by means of imaging in sectional view is introduced to study reflection-type gratings, evading the resolution limit of classical optical microscopy. In addition, this technique is applied to examine so-called parasitic gratings, arising from interference from the incident reference beam and the reflected signal beam. The appearance and possible avoidance of such unintentionally recorded secondary structures is discussed.

  7. Study of a displacement sensor based on transmission varied-line-space phase grating

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jing; OUYANG Min; SHEN Yan; LIU Da-he

    2008-01-01

    A displacement sensor based on transmission varied-line-space (VLS) phase gratings is proposed.The relationship between the properties of the sensor and the parameters of VLS is discussed.Compared with the displacement sensor manufactured by the reflective VLS grating,this type of sensor contains a grating with simpler structure and high diffraction efficiency.It also has good stability with the change of temperature.

  8. Alternative radiative and dark mode-induced multi-broadband transmission in asymmetrical metallic grating

    Science.gov (United States)

    Li, Yue; Fei, Guang Tao; Xu, Shao Hui; Shang, Guo Liang; De Zhang, Li

    2016-01-01

    The phenomenon of extraordinary and multi-broadband optical transmission through sub-wavelength metallic grating with symmetry breaking has been theoretically investigated. Under normal incident light, the radiative and dark modes appear in adjacent slits of the grating with asymmetric heights. Through the destructive interference of alternative radiative and dark modes, multiple broadband transmission and enhanced light propagation is realized. The counter-propagating light circulation results in sharp dips in the transmission spectrum. These characteristics of the asymmetric grating could provide highly controllable ways to design novel devices.

  9. High-resolution x-ray studies of an AXAF high-energy transmission grating

    DEFF Research Database (Denmark)

    Abdali, S.; Christensen, Finn Erland; Schnopper, H. W.;

    1993-01-01

    A triple axis X-ray diffractometer, designed and built at the Danish Space Research Institute, was used to make a high resolution study of the performance of a 2000 angstroms period, high energy X-ray transmission grating developed at MIT for one of the grating spectrometers on the Advanced X...

  10. Unidirectional transmission realized by two nonparallel gratings made of isotropic media.

    Science.gov (United States)

    Ye, Wei-Min; Yuan, Xiao-Dong; Zeng, Chun

    2011-08-01

    We realize a unidirectional transmission by cascading two nonparallel gratings (NPGs) made of isotropic, lossless, and linear media. For a pair of orthogonal linear polarizations, one of the gratings is designed as a polarizer, which is a reflector for one polarization and a transmitter for the other; another grating is designed as a polarization converter, which converts most of one polarized incident wave into another polarized transmitted wave. It is demonstrated by numerical calculation that more than 85% of the incident light energy can be transmitted with less than 1% transmission in the opposite direction for linearly polarized light at normal incidence, and the relative bandwidth of the unidirectional transmission is nearly 9%. The maximum transmission contrast ratio between the two directions is 62 dB. Unlike one-way diffraction grating, the transmitted light of the NPGs is collinear with the incident light, but their polarizations are orthogonal. PMID:21808331

  11. Quasi-sinusoidal single-order diffraction transmission grating used in x-ray spectroscopy.

    Science.gov (United States)

    Kuang, Longyu; Cao, Leifeng; Zhu, Xiaoli; Wu, Shunchao; Wang, Zhebin; Wang, Chuanke; Liu, Shenye; Jiang, Shaoen; Yang, Jiamin; Ding, Yongkun; Xie, Changqing; Zheng, Jian

    2011-10-15

    A novel design of quasi-sinusoidal single-order diffraction transmission grating (QSTG) is proposed, which can achieve a line density up to thousands line/millimeter as that of traditional transmission gratings with the current level of nanofabrication technique. We fabricate a 1000 line/mm QSTG using the new design approach, and display the calibration results of such QSTG on the soft x-ray beam of synchrotron radiation. PMID:22002350

  12. [Transmission grating spectrograph for soft X-ray spectrum measurements with a pre-optics].

    Science.gov (United States)

    Wang, Z; Tian, Z; Chen, B; Wang, Z; Gao, J; Tian, X; Chen, Z; Fan, P; Chen, X

    1999-12-01

    A novel diffraction spectroscopic instrument consisting of a large area transmission grating and a grazing-incidence pre-optics comprising of a toroidal mirror, a slit and a cylindrical mirror has been implemented. A nearly perfect stigmatism and a medium spectral resolution are due to the separation of the focusing and dispersing function. The experimental results show that it is possible to construct large area transmission grating spectrograph with high collecting efficiency and good spatial resolution. PMID:15822323

  13. Soft x-ray blazed transmission grating spectrometer with high resolving power and extended bandpass

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alexander Robert; Schattenburg, Mark

    2016-04-01

    A number of high priority questions in astrophysics can be addressed by a state-of-the-art soft x-ray grating spectrometer, such as the role of Active Galactic Nuclei in galaxy and star formation, characterization of the Warm-Hot Intergalactic Medium and the “missing baryon” problem, characterization of halos around the Milky Way and nearby galaxies, as well as stellar coronae and surrounding winds and disks. An Explorer-scale, large-area (> 1,000 cm2), high resolving power (R = λ/Δλ > 3,000) soft x-ray grating spectrometer is highly feasible based on Critical-Angle Transmission (CAT) grating technology. Still significantly higher performance can be provided by a CAT grating spectrometer on an X-ray-Surveyor-type mission. CAT gratings combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of conventional transmission gratings (low mass, relaxed alignment tolerances and temperature requirements, transparent at higher energies) with minimal mission resource requirements. They are high-efficiency blazed transmission gratings that consist of freestanding, ultra-high aspect-ratio grating bars fabricated from silicon-on-insulator (SOI) wafers using advanced anisotropic dry and wet etch techniques. Blazing is achieved through grazing-incidence reflection off the smooth grating bar sidewalls. The reflection properties of silicon are well matched to the soft x-ray band. Nevertheless, CAT gratings with sidewalls made of higher atomic number elements allow extension of the CAT grating principle to higher energies and larger dispersion angles. We show x-ray data from metal-coated CAT gratings and demonstrate efficient blazing to higher energies and larger blaze angles than possible with silicon alone. We also report on measurements of the resolving power of a breadboard CAT grating spectrometer consisting of a Wolter-I slumped-glass focusing mirror pair from Goddard Space Flight Center and CAT gratings, to be

  14. Resonant transmission and mode modulation of acoustic waves in H-shaped metallic gratings

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yu-Qiang; Fan, Ren-Hao; Zhang, Kun; Peng, Ru-Wen, E-mail: rwpeng@nju.edu.cn, E-mail: dongxiang87@gmail.com [National Laboratory of solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Qi, Dong-Xiang, E-mail: rwpeng@nju.edu.cn, E-mail: dongxiang87@gmail.com [National Laboratory of solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); School of Science, Jiangnan University, Wuxi 214122 (China)

    2015-04-15

    In this work, we demonstrate that resonant full transmission of acoustic waves exists in subwavelength H-shaped metallic gratings, and transmission peaks can be efficiently tuned by adjusting the grating geometry. We investigate this phenomenon through both numerical simulations and theoretical calculations based on rigorous-coupled wave analysis. The transmission peaks are originated from Fabry-Perot resonances together with the couplings between the diffractive wave on the surface and the multiple guided modes in the slits. Moreover, the transmission modes can be efficiently tuned by adjusting the cavity geometry, without changing the grating thickness. The mechanism is analyzed based on an equivalent circuit model and verified by both the theoretical calculations and the numerical simulations. This research has potential application in acoustic-device miniaturization over a wide range of wavelengths.

  15. Plasmonic band edge effects on the transmission properties of metal gratings

    Directory of Open Access Journals (Sweden)

    D. de Ceglia

    2011-09-01

    Full Text Available We present a detailed analysis of the optical properties of one-dimensional arrays of slits in metal films. Although enhanced transmission windows are dominated by Fabry-Perot cavity modes localized inside the slits, the periodicity introduces surface modes that can either enhance or inhibit light transmission. We thus illustrate the interaction between cavity modes and surface modes in both finite and infinite arrays of slits. In particular we study a grating that clearly separates surface plasmon effects from Wood-Rayleigh anomalies. The periodicity of the grating induces a strong plasmonic band gap that inhibits coupling to the cavity modes for frequencies near the center of the band gap, thereby reducing the transmission of the grating. Strong field localization at the high energy plasmonic band edge enhances coupling to the cavity modes while field localization at the low energy band edge leads to weak cavity coupling and reduced transmission.

  16. Analysis of transmission mode of a matched fiber Bragg grating interrogation scheme.

    Science.gov (United States)

    Wade, Scott A; Attard, Daniel P; Stoddart, Paul R

    2010-08-20

    A detailed investigation has been undertaken into the transmission mode of the matched fiber Bragg grating interrogation scheme with respect to its use in optical fiber sensor applications. Analytical and numerical models of the scheme have been developed. Experimental studies presented include the effect of the spectral characteristics of the gratings on system performance, results of strain and compression calibrations, a scheme to correct for intensity fluctuations, and the correction of temperature-induced shifts by collocating sensor and reference gratings. The results are in good agreement with a simplified model of the transmission mode. The analysis provides quantitative relationships between key sensor design parameters, such as sensitivity and measurement range as a function of grating bandwidth. PMID:20733619

  17. Development of lightweight blazed transmission gratings and large-area soft x-ray spectrographs

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alex R.; Guan, Dong; Schattenburg, Mark L.

    2013-09-01

    Large area, high resolving power spectroscopy in the soft x-ray band can only be achieved with a state-of-the-art diffraction grating spectrometer, comprised of large collecting-area focusing optics with a narrow point spread function, large-area high-resolving power diffraction gratings, and small pixel, order sorting x-ray detectors. Recently developed critical-angle transmission (CAT) gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Several new mission concepts containing CAT grating based spectrometers (AEGIS, AXSIO, SMART-X) promise to deliver unprecedented order-of-magnitude improvements in soft x-ray spectroscopy figures of merit related to the detection and characterization of emission and absorption lines, thereby addressing high-priority questions identified in the Astro2010 Decadal Survey "New Worlds New Horizons". We review the current status of CAT grating fabrication, present recent fabrication results, and describe our plans and technology development roadmap for the coming year and beyond.

  18. Study of transmission grating diffraction efficiencies for soft X-ray

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Tansmission grating spectrometers are extensively used tomeasure absolute X-ray spectra in a photon-energy rangebelow 1000 eV. The transmission grating, as its dispersive element, must be calibrated to obtain its diffraction efficiencies.Calibrations of absolute diffraction efficiencies of the transmissiongrating at photon energy of 844 eV have been carried out onBeijing Synchrotron Radiation Facility. With the aid of gratingmodel, all of the grating structure parameters have been determinedand the absolute diffraction efficiencies in a photon-energy rangebelow 2000 eV have also been calculated and discussed.

  19. Normal incidence narrowband transmission filtering capabilities using symmetry-protected modes of a subwavelength, dielectric grating.

    Science.gov (United States)

    Foley, Justin M; Phillips, Jamie D

    2015-06-01

    We computationally study a normal incidence narrowband transmission filter based on a subwavelength dielectric grating that operates through Fano interference between supported guided leaky modes of the system. We characterize the filtering capabilities as the cross section of the grating is manipulated and suggest techniques for experimental demonstration. Using group theory, we study the plane wave coupling to the supported modes that leads to broadband reflectance and narrowband transmittance responses for rectangular, pentagonal, rhomboidal, and right trapezoidal cross-sectional geometries. PMID:26030577

  20. High-Resolution Chandra X-ray Imaging and Spectroscopy of the Sigma Orionis Cluster

    OpenAIRE

    Skinner, S.L.; Sokal, K. R.; Cohen, D. H.; Gagne, M.; Owocki, S.P.; Townsend, R. D.

    2008-01-01

    We present results of a 90 ksec Chandra X-ray observation of the young sigma Orionis cluster (age ~3 Myr) obtained with the High Energy Transmission Grating Spectrometer. We use the high resolution grating spectrum and moderate resolution CCD spectrum of the massive central star sigma Ori AB (O9.5V + B0.5V) to test wind shock theories of X-ray emission and also analyze the high spatial resolution zero-order ACIS-S image of the central cluster region. Chandra detected 42 X-ray sources on the p...

  1. IR color separation in transmission through gratings on (110) silicon: FTIR experiment versus theory

    CERN Document Server

    Auslender, Mark

    2012-01-01

    The phenomenon of filtering in zero-diffraction order is studied for transmission through 1D-periodic structures on a silicon wafer. Our study combines FTIR spectrometry in the range from 2.5 to 25 microns, and a rigorous full-vector simulation. The phenomenon exhibits itself as 'bright' and 'dark' bands in the spectra of normal transmission through grating samples, which replace each other quasi-periodically with respect to wave number, at wavelengths smaller than the grating period. The transmission modulation ratio is extremely high for two-side polished samples. Good agreement between the rigorous theory and experiment both in the range of the transmission oscillations and in the region of enhanced absorption is obtained

  2. Manipulation and analysis of atomic and molecular beams using transmission gratings and Fresnel zone plates

    Energy Technology Data Exchange (ETDEWEB)

    Grisenti, R.E.

    2000-06-01

    In this thesis experimental results on the diffraction of rare gas atoms (He, Ne, Ar, Kr) and molecular (D{sub 2}) beams by a 100 nm period transmission grating and on the focusing of a helium atom beam through a Fresnel zone plate have been reported. (orig.)

  3. Transmission comb of a distributed Bragg reflector induced by two surface dielectric gratings

    CERN Document Server

    Zhao, Xiaobo; Zhang, Yongyou

    2015-01-01

    With transfer matrix theory, we study the transmission of a distributed Bragg reflector (DBR) with two dielectric gratings on top and on the bottom. Owing to the diffraction of the two gratings, the transmission shows a comb-like spectrum which red shifts with increasing the grating period during the forbidden band of the DBR. The number density of the comb peaks increases with increasing the number of the DBR cells, while the ratio of the average full width at half maximum (FWHM) of the transmission peaks in the transmission comb to the corresponding average free spectral range, being about 0.04 and 0.02 for the TE and TM incident waves, is almost invariant. The average FWHM of the TM waves is about half of the TE waves, and both they could be narrower than 0.1 nm. In addition, the transmission comb peaks of the TE and TM waves can be fully separated during certain waveband. We further prove that the transmission comb is robust against the randomness of the heights of the DBR layers, even when a 15\\% randomn...

  4. Transmission and Reflection through $1$D Metallo-Dielectric Gratings of Real Metals under Sub-wavelength Condition

    CERN Document Server

    Rahman, A T M Anishur; Vasilev, Krasimir

    2015-01-01

    Under the sub-wavelength condition ($w<\\lambda/2$), an analytical model of light transmission and reflection through $1$D metallo-dielectric gratings of real metals has been developed. It has been shown that the transmission intensity associated with the Fabry-Perot (FP) resonance of a $1$D metallo-dielectric grating of a real metal decreases with the increasing grating thickness and the dielectric constant of the ridge material. Further, it has also been demonstrated that the intensity of the FP resonance increases with the increasing slit width while it is independent of the grating period ($P$) and the incidence angle (when $P << \\lambda$

  5. Chandra X-ray Grating Spectrometry of Eta Carinae near X-ray Minimum: I. Variability of the Sulfur and Silicon Emission Lines

    CERN Document Server

    Henley, D B; Pittard, J M; Stevens, I R; Hamaguchi, K; Gull, T R

    2008-01-01

    We report on variations in important X-ray emission lines in a series of Chandra grating spectra of the supermassive colliding wind binary star Eta Carinae, including key phases around the X-ray minimum/periastron passage in 2003.5. The X-rays arise from the collision of the slow, dense wind of Eta Car with the fast, low-density wind of an otherwise hidden companion star. The X-ray emission lines provide the only direct measure of the flow dynamics of the companion's wind along the wind-wind collision zone. We concentrate here on the silicon and sulfur lines, which are the strongest and best resolved lines in the X-ray spectra. Most of the line profiles can be adequately fit with symmetric Gaussians with little significant skewness. Both the silicon and sulfur lines show significant velocity shifts and correlated increases in line widths through the observations. The R = forbidden-to-intercombination ratio from the Si XIII and S XV triplets is near or above the low-density limit in all observations, suggestin...

  6. Transmission Properties of THz Radiation Pulses through Very Deep Zero-Order Metallic Gratings

    Institute of Scientific and Technical Information of China (English)

    XING Qi-Rong; LI Shu-Xin; ZHANG Wei-Li; LANG Li-Ying; MAO Fang-Lin; XU Shi-Xiang; CHAI Lu; WANG Qing-Yue

    2005-01-01

    @@ Very deep zero-order metallic grating structures are processed to study the transmission properties of THz radiation pulses. The experiments have been performed with two samples. The delay of the THz pulses and the corresponding resonantly enhanced transmission spectra through the samples are observed. To explain the extraordinary transmission we have treated the samples as Fabry-Perot resonators through resonant excitation of the coupled surface plasmon polaritons filled in the cavities between the metal slats. The experimental results are in reasonable agreement with the numerical simulation. Our results show that THz-time-domain spectroscopy may be an effective technique for studying the optical properties of various THz microstructured devices.

  7. Transmission spectra of coated phase shifted long-period fiber gratings

    Institute of Scientific and Technical Information of China (English)

    GU Zheng-tian; ZHAO Xiao-yun; ZHANG Jiang-tao

    2009-01-01

    The transmission spectrum of the coated phase-shifted long-period fiber gratings (LPFGs) with single and multiple phase shifts is analyzed by the coupled-mode theory and the transfer matrix method, and the influences of the film parameters on the spectral characteristics are also studied. It is shown that these parameters will affect the LPFG filtering characteristics. The loss peak of transmission spectrum decreases with the increase of film thickness, and the peak position shifts with the film refractive index. Compared with the non-coated phase-shifted LPFG, the coated one has the similar desirable filtering characteristics, and it has a flexile ability to adjust the transmission properties.

  8. Humidity and Temperature Effect on Properties of Transmission Gratings Recorded in PVA/AA-Based Photopolymer Layers

    OpenAIRE

    Mikulchyk, Tatsiana; Martin, Suzanne; Naydenova, Izabela

    2013-01-01

    This paper explores the effects of humidity on gratings recorded in a polyvinylalcohol–acrylamide photopolymer medium. Investigation of the behaviour of transmission gratings exposed to high humidity is of significant interest for two reasons, firstly because the grating's sensitivity to humidity can be exploited for the development of irreversible humidity indicators, secondly because too much sensitivity to humidity can limit the use of these materials in applications where an environmental...

  9. High Sensitivity Transmission-Type SPR Sensor by Using Metallic-Dielectric Mixed Gratings

    Institute of Scientific and Technical Information of China (English)

    WU Bin; WANG Qing-Kang

    2008-01-01

    We theoretically investigate transmission-type SPR sensors with novel metallic-dielectric mixed gratings by rigorous coupled-wave analysis (RCWA),compared to the conventional dielectric gratings based structure.It is found that the transmittance efficiency and the full width at half-maximum (FWHM) of the transmission curve can be modulated by increasing or decreasing the metallic part.Therefore,appropriate proportion of metal part will induce enhancement factor of sensor merit.Furthermore,this novel structure will also bring enhancement of resonant angle shift,which can be explained by plasmonic interpretation based on a surface limited increase of interaction area and excitation of localized surface plasmons (LSPs).The proposed configuration has a wide range of potential applications not only as sensor but also other optical devices.

  10. Study on transmission characteristics of photonic crystal fiber gratings with periodic air hole deformation

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-yan; TIAN Che; QI Yue-feng; GUO Wen-guang

    2011-01-01

    The paper studies a kind of improved photonic crystal fiber gratings fabricated by CO2 laser heating method.The effective refractive index of cladding induced by periodic air hole deformation is computed using multipole method,and the relationship between the effective refractive index and the collapse of air-holes is discussed,thereby the modulation expression of effective refractive index is obtained.The grating transmission characteristics are simulated.The results indicate that with the diameter of air-holes increasing from 3.3 μm to 3.7 μ.m,the resonance wavelength shows blue-shift,the resonance peak intensifies,and the bandwidth becomes narrow.As the collapse degree of cladding enhances,the resonance wavelength shows red-shift,the transmission increases,and the bandwidth tends to narrow.

  11. Time-resolved x-ray transmission grating spectrometer for studying laser-produced plasmas.

    Science.gov (United States)

    Ceglio, N M; Kauffman, R L; Hawryluk, A M; Medecki, H

    1983-01-15

    The development of a new time-resolved x-ray spectrometer is reported in which a free-standing x-ray transmission grating is coupled to a soft x-ray streak camera. The instrument measures continuous x-ray spectra with 20-psec temporal resolution and moderate spectral resolution (deltalambda >/= 1 A) over a broad spectral range (0.1-5 keV) with high sensitivity and large information recording capacity. Its capabilities are well suited to investigation of laser-generated plasmas, and they nicely complement the characteristics of other time-resolved spectroscopic techniques presently in use. The transmission grating spectrometer has been used on a variety of laser-plasma experiments. We report the first measurements of the temporal variation of continuous low-energy x-ray spectra from laser-irradiated disk targets. PMID:18195786

  12. Single-shot calibration of soft x-ray mirrors using a sinusoidal transmission grating

    Science.gov (United States)

    Shpilman, Z.; Ehrlich, Y.; Maman, S.; Levy, I.; Shussman, T.; Oren, G.; Zakosky Nueberger, I.; Hurvitz, G.

    2014-11-01

    Calibration of soft x-ray diagnostics is a challenge due to the lack of laboratory-size calibrated sources. An in situ calibration method for newly developed x-ray mirrors, is presented. The x-ray source is produced by laser-matter interaction, and twin transmission gratings which create two identical dispersion lines. The gratings have a sinusoidal transmission function, which produces a highly precise high-orders free spectrum. An x-ray mirror interacts with one of the dispersion lines, and the mirror efficiency curve as a function of wavelength is extracted. Mirror efficiency shows good agreement with the literature, and evidence of water layer may justify the need of in situ calibration.

  13. Development and commissioning of a transmission grating spectrometer on the National Ignition Facility

    Science.gov (United States)

    Guymer, T. M.; Moore, A. S.; Morton, J.; Stevenson, R. M.

    2013-03-01

    The design and calibration of a soft X-ray transmission grating imaging spectrometer for the National Ignition Facility (NIF) [1] has been discussed elsewhere [2] and will be summarised here for ease. This work primarily discusses the supporting modelling and analysis techniques associated with the transmission grating spectrometer (TGS) and provides further analysis of the dedicated qualification shot on the NIF. Comparisons are made between: the CASSANDRA [3] opacity tables (used within the radiation-hydrodynamics code NYM [4]); the opacity derived from FLYCHK [5]; and the obtained spectrum using different analysis methods. Consideration is also given to the spectral resolution [6] of the diagnostic, the design aims of the diagnostic and limitations in the utilised codes.

  14. Single-shot calibration of soft x-ray mirrors using a sinusoidal transmission grating.

    Science.gov (United States)

    Shpilman, Z; Ehrlich, Y; Maman, S; Levy, I; Shussman, T; Oren, G; Zakosky Nueberger, I; Hurvitz, G

    2014-11-01

    Calibration of soft x-ray diagnostics is a challenge due to the lack of laboratory-size calibrated sources. An in situ calibration method for newly developed x-ray mirrors, is presented. The x-ray source is produced by laser-matter interaction, and twin transmission gratings which create two identical dispersion lines. The gratings have a sinusoidal transmission function, which produces a highly precise high-orders free spectrum. An x-ray mirror interacts with one of the dispersion lines, and the mirror efficiency curve as a function of wavelength is extracted. Mirror efficiency shows good agreement with the literature, and evidence of water layer may justify the need of in situ calibration.

  15. Characterization of imprinted gratings based on transparent materials by transmission scatterometry

    KAUST Repository

    Pietroy, David

    2013-06-01

    Transmission scatterometry is studied as a characterization tool for gratings nanoimprinted in a resist layer spincoated on the top of a transparent substrate. In this case, the larger part of the incident signal is transmitted which can make the reflection analysis harder. Although the backward reflections in the substrate induce an error which is difficult to correct, results are shown to be in good agreement with SEM measurements and reflection mode scatteromerty. © 2013 Elsevier B.V. All rights reserved.

  16. Space-Resolved Spectrum Diagnose by Soft X-Ray Transmission Grating Spectrometer

    Science.gov (United States)

    Shang, Wanli; Zhao, Yang; Xiong, Gang; Yang, Jiamin; Zhu, Tuo

    2011-02-01

    A space-resolving transmission grating spectrometer is established on the “Shenguang-III" prototype laser facility and an iterative procedure for unfolding the X-ray spectrum with spatial resolution is described. The diagnostics is applied to measure the X-ray spectrum from laser-entered gold target and the typical space-resolved spectrum is provided. The relative standard uncertainty of the X-ray spectrum from the laser-generated plasma is also determined.

  17. Transmission comb of a distributed Bragg reflector with two surface dielectric gratings

    Science.gov (United States)

    Zhao, Xiaobo; Zhang, Yongyou; Zhang, Qingyun; Zou, Bingsuo; Schwingenschlogl, Udo

    2016-02-01

    The transmission behaviour of a distributed Bragg reector (DBR) with surface dielectric gratings on top and bottom is studied. The transmission shows a comb-like spectrum in the DBR band gap, which is explained in the Fano picture. The number density of the transmission peaks increases with increasing number of cells of the DBR, while the ratio of the average full width at half maximum to the corresponding average free spectral range, being only few percent for both transversal electric and magnetic waves, is almost invariant. The transmission peaks can be narrower than 0.1 nm and are fully separated from each other in certain wavebands. We further prove that the transmission combs are robust against randomness in the heights of the DBR layers. Therefore, the proposed structure is a candidate for an ultra-narrow-band multichannel filter or polarizer.

  18. Transmission comb of a distributed Bragg reflector with two surface dielectric gratings

    KAUST Repository

    Zhao, Xiaobo

    2016-02-19

    The transmission behaviour of a distributed Bragg reector (DBR) with surface dielectric gratings on top and bottom is studied. The transmission shows a comb-like spectrum in the DBR band gap, which is explained in the Fano picture. The number density of the transmission peaks increases with increasing number of cells of the DBR, while the ratio of the average full width at half maximum to the corresponding average free spectral range, being only few percent for both transversal electric and magnetic waves, is almost invariant. The transmission peaks can be narrower than 0.1 nm and are fully separated from each other in certain wavebands. We further prove that the transmission combs are robust against randomness in the heights of the DBR layers. Therefore, the proposed structure is a candidate for an ultra-narrow-band multichannel filter or polarizer.

  19. PHOTOIONIZATION MODELING OF OXYGEN K ABSORPTION IN THE INTERSTELLAR MEDIUM: THE CHANDRA GRATING SPECTRA OF XTE J1817-330

    Energy Technology Data Exchange (ETDEWEB)

    Gatuzz, E.; Mendoza, C. [Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), P.O. Box 20632, Caracas 1020A (Venezuela, Bolivarian Republic of); Garcia, J.; Lohfink, A. [Department of Astronomy and Maryland Astronomy Center for Theory and Computation, University of Maryland, College Park, MD 20742 (United States); Kallman, T. R.; Witthoeft, M. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bautista, M. A. [Department of Physics, Western Michigan University, Kalamazoo, MI 49008 (United States); Palmeri, P.; Quinet, P., E-mail: egatuzz@ivic.gob.ve, E-mail: claudio@ivic.gob.ve, E-mail: javier@astro.umd.edu, E-mail: alohfink@astro.umd.edu, E-mail: timothy.r.kallman@nasa.gov, E-mail: michael.c.witthoeft@nasa.gov, E-mail: manuel.bautista@wmich.edu, E-mail: palmeri@umons.ac.be, E-mail: quinet@umons.ac.be [Astrophysique et Spectroscopie, Universite de Mons-UMONS, B-7000 Mons (Belgium)

    2013-05-01

    We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the XSTAR code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain a column density of N{sub H} = 1.38 {+-} 0.01 Multiplication-Sign 10{sup 21} cm{sup -2}; an ionization parameter of log {xi} = -2.70 {+-} 0.023; an oxygen abundance of A{sub O}= 0.689{sup +0.015}{sub -0.010}; and ionization fractions of O I/O = 0.911, O II/O = 0.077, and O III/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse and Sauval, a rescaling with the revision by Asplund et al. yields A{sub O}=0.952{sup +0.020}{sub -0.013}, a value close to solar that reinforces the new standard. We identify several atomic absorption lines-K{alpha}, K{beta}, and K{gamma} in O I and O II and K{alpha} in O III, O VI, and O VII-the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n > 2 associated with ISM cold absorption.

  20. Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

    CERN Document Server

    Heilmann, Ralf K; Kolodziejczak, Jeffery; Gaskin, Jessica A; O'Dell, Stephen L; Bhatia, Ritwik; Schattenburg, Mark L

    2016-01-01

    Several high priority subjects in astrophysics can be addressed by a state-of-the-art soft x-ray grating spectrometer (XGS). An Explorer-scale, large-area (> 1,000 cm2), high resolving power (R > 3,000) XGS is highly feasible based on Critical-Angle Transmission (CAT) gratings, even for telescopes with angular resolution of 5-10 arcsec. Significantly higher performance can be provided by a CAT XGS on an X-ray-Surveyor-type mission. CAT gratings combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of transmission gratings (low mass, relaxed alignment and temperature requirements, transparent at high energies) with minimal mission resource demands. They are high-efficiency blazed transmission gratings that consist of freestanding, ultra-high aspect-ratio grating bars made from SOI wafers using anisotropic dry and wet etch techniques. Blazing is achieved through reflection off grating bar sidewalls. Silicon is well matched to the soft x-ray band, and...

  1. Chandra X-ray Grating Spectrometry of Eta Carinae near X-ray Minimum: I. Variability of the Sulfur and Silicon Emission Lines

    Science.gov (United States)

    Henley, D. B.; Corcoran, M. F.; Pittard, J. M.; Stevens, I. R.; Hamaguchi, K.; Gull, T. R.

    2008-01-01

    We report on variations in important X-ray emission lines in a series of Chandra grating spectra of the supermassive colliding wind binary star eta Car, including key phases around the X-ray minimum/periastron passage in 2003.5. The X-rays arise from the collision of the slow, dense wind of eta Car with the fast, low-density wind of an otherwise hidden companion star. The X-ray emission lines provide the only direct measure of the flow dynamics of the companion's wind along the wind-wind collision zone. We concentrate here on the silicon and sulfur lines, which are the strongest and best resolved lines in the X-ray spectra. Most of the line profiles can be adequately fit with symmetric Gaussians with little significant skewness. Both the silicon and sulfur lines show significant velocity shifts and correlated increases in line widths through the observations. The R = forbidden-to-intercombination ratio from the Si XIII and S XV triplets is near or above the low-density limit in all observations, suggesting that the line-forming region is > 1.6 stellar radii from the companion star, and that the emitting plasma may be in a non-equilibrium state. We show that simple geometrical models cannot simultaneously fit both the observed centroid variations and changes in line width as a function of phase. We show that the observed profiles can be fitted with synthetic profiles with a reasonable model of the emissivity along the wind-wind collision boundary. We use this analysis to help constrain the line formation region as a function of orbital phase, and the orbital geometry. Subject headings: X-rays: stars -stars: early-type-stars: individual (q Car)

  2. Generation of tunable-volume transmission-holographic gratings at low light levels

    International Nuclear Information System (INIS)

    By utilizing giant Kerr nonlinearity obtained by electromagnetically induced transparency (EIT), tunable volume transmission holographic gratings for a weak probe field can be generated by means of a standing-wave signal field at low light levels in a four-level N-type ultracold atomic ensemble. The induced grating can be characterized as a mixed volume holographic grating with a strong phase modulation accompanied by a weak amplitude modulation. Based on Kogelnik's coupled-wave theory in optical holography, we find that high diffraction efficiency (up to 85%) and sensitive angular selectivity (up to ±0.000149 rad) can be achieved for the induced grating in the Bragg diffraction regime. And, both of them can be dynamically controlled by tuning the weak standing-wave signal field and the coupling field. Our study not only develops a fundamental understanding of volume diffraction effects in EIT media, but also provides a practical prototype of EIT-based holographic devices for all-optical classical and quantum information processing.

  3. Single-Order Transmission Diffraction Gratings based on Dispersion Engineered All-dielectric Metasurfaces

    CERN Document Server

    Gupta, Shulabh

    2016-01-01

    A single-order transmission diffraction grating based on dispersion engineered all-dielectric metasurfaces is proposed and its wavelength discriminating properties have been theoretically described and confirmed using numerical simulations. The metasurface is designed using a 2D array of all-dielectric resonators, which emulates a Huygens source configuration to achieve a perfect match to free-space in broad bandwidth. Using a holey dielectric nanodisk structure as the unit cell, the resonant wavelength is tapered across the metasurface to engineer the wavelength dependent spatial phase gradient, to emulate a dispersive prism. Consequently, different wavelengths are steered towards different directions and thus are discriminated on the output image plane. Due to subwavelength periodicities involved, the wavelength discrimination is achieved directly in the zeroth diffraction order of the device, unlike conventional diffraction gratings, thereby providing a high efficiency wavelength discriminating device.

  4. Single-order transmission diffraction gratings based on dispersion engineered all-dielectric metasurfaces.

    Science.gov (United States)

    Gupta, Shulabh

    2016-08-01

    A single-order transmission diffraction grating based on dispersion engineered all-dielectric metasurfaces is proposed, and its wavelength discriminating properties have been theoretically described and confirmed using numerical simulations. The metasurface is designed using a 2D array of all-dielectric resonators, which emulates a Huygens' source configuration to achieve a perfect match to free space in broad bandwidth. Using a holey dielectric nanodisk structure as the unit cell, the resonant wavelength is tapered across the metasurface to engineer the wavelength-dependent spatial phase gradient, to emulate a dispersive prism. Consequently, different wavelengths are steered toward different directions and thus are discriminated on the output image plane. Due to the subwavelength periodicities involved, wavelength discrimination is achieved directly in the zeroth diffraction order of the device, unlike conventional diffraction gratings, thereby providing a high-efficiency wavelength discriminating device. PMID:27505664

  5. Dense WDM transmission at 2  μm enabled by an arrayed waveguide grating.

    Science.gov (United States)

    Zhang, H; Gleeson, M; Ye, N; Pavarelli, N; Ouyang, X; Zhao, J; Kavanagh, N; Robert, C; Yang, H; Morrissey, P E; Thomas, K; Gocalinska, A; Chen, Y; Bradley, T; Wooler, J P; Hayes, J R; Numkam Fokoua, E; Li, Z; Alam, S U; Poletti, F; Petrovich, M N; Richardson, D J; Kelly, B; O'Carroll, J; Phelan, R; Pelucchi, E; O'Brien, P; Peters, F; Corbett, B; Gunning, F

    2015-07-15

    We show, for the first time, dense WDM (8×20  Gbit/s) transmission at 2 μm enabled by advanced modulation formats (4-ASK Fast-OFDM) and the development of key components, including a new arrayed waveguide grating (AWGr) at 2 μm. The AWGr shows -12.8±1.78  dB of excess loss with an 18-dB extinction ratio and a thermal tunability of 0.108 nm/°C. PMID:26176456

  6. Curved gratings as an integrated photon fluence monitor in x-ray transmission scattering experiments.

    Science.gov (United States)

    Schneider, Michael; Günther, Christian Michael; von Korff Schmising, Clemens; Pfau, Bastian; Eisebitt, Stefan

    2016-06-13

    A concept to obtain a measure of the photon flux accepted by a solid sample in single-shot transmission experiments with extreme ultraviolet (XUV) or soft x-ray radiation is demonstrated. Shallow, continuously distorted gratings are used to diffract a constant fraction of the incident photons onto an extended area of a CCD detector. The signal can be tailored to fit the dynamic range of the detector, i.e. matching the scattered intensity of the studied structure of interest. Furthermore, composite grating designs that also allow for the measurement of the spatial photon distribution on the sample are demonstrated. The gratings are directly fabricated by focused ion-beam (FIB) lithography into a Si3N4 membrane that supports the actual sample layer. This allows for rapid fabrication of hundreds of samples, making the concept suitable for systematic studies in destructive single-shot measurements at free-electron laser (FEL) sources. We demonstrate relative photon flux measurements in magnetic scattering experiments with synchrotron and FEL radiation at 59.6 eV photon energy. PMID:27410328

  7. Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

    OpenAIRE

    Heilmann, Ralf K.; Bruccoleri, Alexander R.; Kolodziejczak, Jeffery; Gaskin, Jessica A.; O'Dell, Stephen L.; Bhatia, Ritwik; Schattenburg, Mark L.

    2016-01-01

    Several high priority subjects in astrophysics can be addressed by a state-of-the-art soft x-ray grating spectrometer (XGS). An Explorer-scale, large-area (> 1,000 cm2), high resolving power (R > 3,000) XGS is highly feasible based on Critical-Angle Transmission (CAT) gratings, even for telescopes with angular resolution of 5-10 arcsec. Significantly higher performance can be provided by a CAT XGS on an X-ray-Surveyor-type mission. CAT gratings combine the advantages of blazed reflection grat...

  8. Composite second-order performance improvement in optical fibre CATV transmission system using chirped fibre grating

    Institute of Scientific and Technical Information of China (English)

    Ye Qing; Liu Feng; Cai Hai-Wen; Qu Rong-Hui; Fang Zu-Jie

    2005-01-01

    Theoretically, we analyse the dispersion compensation characteristics of the chirped fibre grating (CFG) in an optical fibre cable television (CATV) system and obtain the analytic expression of the composite second-order (CSO)distortion using the time-domain form of the field envelope wave equation. The obtained result is in good agreement with the numerical simulation result. Experimentally, we verify the result by making use of the tunable characteristics of CFG to change the dispersion compensation amount and obtain an optimal CSO performance in a 125km fibre transmission link. Both the theoretical and experimental results show that the CSO performance can be improved by properly choosing the dispersion compensation amount for a certain fibre transmission link.

  9. Dispersion compensation of fiber Bragg gratings in 3100 km high speed optical fiber transmission system

    Institute of Scientific and Technical Information of China (English)

    Li PEI; Tigang NING; Fengping YAN; Xiaowei DONG; Zhongwei TAN; Yan LIU; Shuisheng JIAN

    2009-01-01

    By optimizing the fabrication process of the chirped optical fiber Bragg grating (CFBG), some key problems of CFBG are solved, such as fabrication repetition, temperature stability, group delay ripple (GDR), fluctuation of the reflection spectrum, polarization mode dispersion (PMD), interaction of cascaded CFBG, and so on. The CFBG we fabricated can attain a temperature coefficient less than 0.0005 nm/℃, and the smoothed GDR and the fluctuation of the reflection spectrum are smaller than 10ps and 0.5dB, respec-tively. The PMD of each CFBG is less than 1 ps and the dispersion of each grating is larger than -2600 ps/(nm·km). With dispersion compensated by the CFBGs we fabricated, a 13×10 Gbit/s 3100 km ultra long G.652 fiber transmission system is successfully imple-mented without electric regenerator. The bit error rate (BER) of the system is below 10-4 without forward error correction (FEC); when FEC is added, the BER is below 10-12. The power penalty of the carrier-suppressed return-to-zero (CSRZ) code transmission system is only 2.5 dB.

  10. The Chandra/HETG view of NGC 1365 in a Compton-thick state

    OpenAIRE

    Nardini, E.; Gofford, J; Reeves, JN; Braito, V.; Risaliti, G.; Costa, M.

    2015-01-01

    We present the analysis of a Chandra High-Energy Transmission Grating (HETG) observation of the local Seyfert galaxy NGC 1365. The source, well known for its dramatic X-ray spectral variability, was caught in a reflection-dominated, Compton-thick state. The high spatial resolution afforded by Chandra allowed us to isolate the soft X-ray emission from the active nucleus, neglecting most of the contribution from the kpc-scale starburst ring. The HETG spectra thus revealed a wealth of He- and H-...

  11. Effects of monomer functionality on performances of scaffolding morphologic transmission gratings recorded in polymer dispersed liquid crystals

    International Nuclear Information System (INIS)

    The effects of monomer functionality on performances of holographic polymer dispersed liquid crystal (HPDLC) transmission gratings are systematically investigated. Acrylate monomers with an average functionality ranging from 2.0 to 5.0 are used to prepare these samples. We find scaffolding morphologic transmission gratings (characterized by a high phase separation degree, a well alignment of LCs and low scattering loss) can be obtained irrespective of the monomer functionality, although the exact optimal curing intensity varies. The temporal evolution of the grating formation is studied and the onset time of the LC phase separation decreases significantly with the increase in average monomer functionality. It is also shown that the gratings prepared from low average functionality monomers require a comparatively low switch-off electric field (∼8 V μm−1) whilst suffering from mechanical fragility and long-term instability. Our results not only provide a complete understanding of scaffolding morphologic gratings in terms of the material composition effect, but also provide insight into the formation mechanisms of non-droplet morphologic HPDLC gratings. (paper)

  12. The origin of emission and absorption features in Ton S180 Chandra observations

    OpenAIRE

    Różańska, A.; Czerny, B.; Siemiginowska, A.; Dumont, A. -M.; Kawaguchi, T.

    2003-01-01

    We present new interpretation of Ton S180 spectrum obtained by {\\it Chandra} Spectrometer (Low Energy Transmission Grating). Several narrow absorption lines and a few emission disk lines have been successfully fitted to the data. We have not found any significant edges accompanying line emission. We propose the interpretation of narrow lines consistent with the paper recently written by Krolik (2002), where warm absorber is strongly inhomogeneous. Such situation is possible in so called multi...

  13. A soft x-ray transmission grating imaging-spectrometer for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Moore, A. S.; Guymer, T. M.; Morton, J.; Bentley, C.; Stevenson, M. [Directorate Science and Technology, AWE Aldermaston, Reading, RG7 4PR (United Kingdom); Kline, J. L.; Taccetti, M.; Lanier, N. E.; Workman, J.; Peterson, B.; Mussack, K.; Cowan, J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Prasad, R.; Richardson, M.; Burns, S.; Kalantar, D. H.; Benedetti, L. R.; Bell, P.; Bradley, D.; Hsing, W. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States)

    2012-10-15

    A soft x-ray transmission grating spectrometer has been designed for use on high energy-density physics experiments at the National Ignition Facility (NIF); coupled to one of the NIF gated x-ray detectors it records 16 time-gated spectra between 250 and 1000 eV with 100 ps temporal resolution. The trade-off between spectral and spatial resolution leads to an optimized design for measurement of emission around the peak of a 100-300 eV blackbody spectrum. Performance qualification results from the NIF, the Trident Laser Facility and vacuum ultraviolet beamline at the National Synchrotron Light Source, evidence a <100 {mu}m spatial resolution in combination with a source-size limited spectral resolution that is <10 eV at photon energies of 300 eV.

  14. Calibrated time-resolved transmission grating spectrometer for the study of ultrafast x-ray sources.

    Science.gov (United States)

    Pelletier, J F; Chaker, M; Kieffer, J C

    1996-01-01

    A transmission grating spectrometer has been coupled to a high-temporal-resolution soft x-ray streak camera for the study of picosecond laser-plasma x-ray sources. A procedure to deconvolve the overlapping contributions of diffraction orders and to calibrate the instrument has been established in order to obtain absolute time-resolved x-ray emission spectra in the 0.1-1.2 keV spectral region. The deconvolution and calibration techniques are presented along with measurements establishing the temporal resolution of this diagnostic at ~2 ps. Examples of calibrated spectra of laser-plasma x-ray sources created by 400 fs laser pulses at intensities of 1018 W/cm2 are also shown. PMID:21307534

  15. A soft x-ray transmission grating imaging-spectrometer for the National Ignition Facility

    Science.gov (United States)

    Moore, A. S.; Guymer, T. M.; Kline, J. L.; Morton, J.; Taccetti, M.; Lanier, N. E.; Bentley, C.; Workman, J.; Peterson, B.; Mussack, K.; Cowan, J.; Prasad, R.; Richardson, M.; Burns, S.; Kalantar, D. H.; Benedetti, L. R.; Bell, P.; Bradley, D.; Hsing, W.; Stevenson, M.

    2012-10-01

    A soft x-ray transmission grating spectrometer has been designed for use on high energy-density physics experiments at the National Ignition Facility (NIF); coupled to one of the NIF gated x-ray detectors it records 16 time-gated spectra between 250 and 1000 eV with 100 ps temporal resolution. The trade-off between spectral and spatial resolution leads to an optimized design for measurement of emission around the peak of a 100-300 eV blackbody spectrum. Performance qualification results from the NIF, the Trident Laser Facility and vacuum ultraviolet beamline at the National Synchrotron Light Source, evidence a <100 μm spatial resolution in combination with a source-size limited spectral resolution that is <10 eV at photon energies of 300 eV.

  16. Fiber Bragg Grating Sensor for Fault Detection in Radial and Network Transmission Lines

    Science.gov (United States)

    Moghadas, Amin A.; Shadaram, Mehdi

    2010-01-01

    In this paper, a fiber optic based sensor capable of fault detection in both radial and network overhead transmission power line systems is investigated. Bragg wavelength shift is used to measure the fault current and detect fault in power systems. Magnetic fields generated by currents in the overhead transmission lines cause a strain in magnetostrictive material which is then detected by Fiber Bragg Grating (FBG). The Fiber Bragg interrogator senses the reflected FBG signals, and the Bragg wavelength shift is calculated and the signals are processed. A broadband light source in the control room scans the shift in the reflected signal. Any surge in the magnetic field relates to an increased fault current at a certain location. Also, fault location can be precisely defined with an artificial neural network (ANN) algorithm. This algorithm can be easily coordinated with other protective devices. It is shown that the faults in the overhead transmission line cause a detectable wavelength shift on the reflected signal of FBG and can be used to detect and classify different kind of faults. The proposed method has been extensively tested by simulation and results confirm that the proposed scheme is able to detect different kinds of fault in both radial and network system. PMID:22163416

  17. Fiber Bragg Grating Sensor for Fault Detection in Radial and Network Transmission Lines

    Directory of Open Access Journals (Sweden)

    Mehdi Shadaram

    2010-10-01

    Full Text Available In this paper, a fiber optic based sensor capable of fault detection in both radial and network overhead transmission power line systems is investigated. Bragg wavelength shift is used to measure the fault current and detect fault in power systems. Magnetic fields generated by currents in the overhead transmission lines cause a strain in magnetostrictive material which is then detected by Fiber Bragg Grating (FBG. The Fiber Bragg interrogator senses the reflected FBG signals, and the Bragg wavelength shift is calculated and the signals are processed. A broadband light source in the control room scans the shift in the reflected signal. Any surge in the magnetic field relates to an increased fault current at a certain location. Also, fault location can be precisely defined with an artificial neural network (ANN algorithm. This algorithm can be easily coordinated with other protective devices. It is shown that the faults in the overhead transmission line cause a detectable wavelength shift on the reflected signal of FBG and can be used to detect and classify different kind of faults. The proposed method has been extensively tested by simulation and results confirm that the proposed scheme is able to detect different kinds of fault in both radial and network system.

  18. Design of Time-Resolved Shifted Dual Transmission Grating Spectrometer for the X-Ray Spectrum Diagnostics

    Science.gov (United States)

    Wang, Baoqing; Yi, Tao; Wang, Chuanke; Zhu, Xiaoli; Li, Tingshuai; Li, Jin; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun

    2016-07-01

    A new time-resolved shifted dual transmission grating spectrometer (SDTGS) is designed and fabricated in this work. This SDTGS uses a new shifted dual transmission grating (SDTG) as its dispersive component, which has two sub transmission gratings with different line densities, of 2000 lines/mm and 5000 lines/mm. The axes of the two sub transmission gratings in SDTG are horizontally and vertically shifted a certain distance to measure a broad range of 0.1-5 keV time-resolved X-ray spectra. The SDTG has been calibrated with a soft X-ray beam of the synchrotron radiation facility and its diffraction efficiency is also measured. The designed SDTGS can take full use of the space on a record panel and improve the precision for measuring spatial and temporal spectrum simultaneously. It will be a promising application for accurate diagnosis of the soft X-ray spectrum in inertial confinement fusion. supported by National Natural Science Foundation of China (Nos. 11405158 and 11435011) and Development Foundation of China Academy of Engineering Physics (Nos. 2014B0102011 and 2014B0102012)

  19. High-resolution X-ray spectroscopy of Procyon by Chandra and XMM-Newton

    OpenAIRE

    Raassen, A.J.J.; Mewe, R.; Audard, M.; Guedel, M.; Behar, E; Kaastra, J.S.; Van Der Meer, R.L.J.; Foley, C. R.; Ness, J.-U.

    2002-01-01

    We report the analysis of the high-resolution soft X-ray spectrum of the nearby F-type star Procyon in the wavelength range from 5 to 175 Angstrom obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board Chandra and with the Reflection Grating Spectrometers (RGS) and the EPIC-MOS CCD spectrometers on board XMM-Newton. Line fluxes have been measured separately for the RGS and LETGS. Spectra have been fitted globally to obtain self-consistent temperatures, emission measur...

  20. Giant reflection band and anomalous negative transmission in a resonant dielectric grating slab: application to a planar cavity

    CERN Document Server

    Pilozzi, L; Tomassini, N; D'Andrea, A

    2012-01-01

    The fundamental optical effects that are at basis of giant reflection band and anomalous negative transmission in a self-sustained rectangular dielectric grating slab in P polarization and for incidence angle not very far from the Brewster's angle of the equivalent slab, are investigated. Notice, that the self sustained dielectric grating slab is the simplest system that, due to the Bragg diffraction, can show both the former optical effects. A systematic study of its optical response is performed by an analytical exact solution of the Maxwell equations for a general incidence geometry. At variance of the well known broad reflection bands in high contrast dielectric grating slab in the sub-wavelength regime, obtained by the destructive interference between the travelling fundamental wave and the first diffracted wave (a generalization of the so called second kind Wood's anomalies), the giant reflection band is a subtle effect due to the interplay, as well as among the travelling fundamental wave and the first...

  1. Linear to radial/azimuthal polarization converter in transmission using form birefringence in a segmented silicon grating manufactured by high productivity microelectronic technologies

    OpenAIRE

    Kampfe, Thomas; Sixt, Pierre; Renaud, Denis; Lagrange, Armelle; Perrin, Fabrice; Parriaux, Olivier

    2014-01-01

    International audience A polarization rotation is realized by subwavelength binary gratings, where the TE and TM round trip phases of the smallest grating modes are fixed to the smallest possible integer numbers of 2pi that allow a straight-through phase difference of pi This results in a subwavelength grating allowing to realize a half-wave element of almost 100% transmission. The principle is applied to a polarization transformation in the 1030-1064 nm wavelength range, using a segmented...

  2. Design of a transmission grating hard X-ray spectrometer for laser-driven undulator sources

    Energy Technology Data Exchange (ETDEWEB)

    Werle, Christian; Maier, Andreas; Zeitler, Benno; Delbos, Niels; Gruener, Florian [University of Hamburg - CFEL, Hamburg (Germany); Kajumba, Nathaniel [Ludwig Maximilian Univ., Muenchen (Germany)

    2013-07-01

    State-of-the-art laser-driven undulator sources are already becoming very versatile and powerful light sources, especially due to their wavelength tunability and ultra-short pulses. However, being still in development, they suffer from instabilities, which can make the spectral characterization of their radiation rather challenging, especially in the few-nm range. The hard X-ray transmission grating spectrometer, presented in this talk, was specifically optimized to tackle these difficulties. Its simple base design and its fully motorized optical components grant a high degree of flexibility during operation, fitting nicely to the nature of this radiation source. During calibration the device has been proven to measure wavelengths from 18 nm to 5 nm, but was in general also designed to address the sub-nm range. Following these test runs, the spectrometer was installed during a undulator campaign and was successfully used to measure laser-driven undulator radiation from 100 eV up to 300 eV, being the highest energy photons ever demonstrated with such a source.

  3. Transmission-type SPR sensor based on coupling of surface plasmons to radiation modes using a dielectric grating

    Institute of Scientific and Technical Information of China (English)

    Changkui HU; Deming LIU

    2009-01-01

    A transmission-type surface plasmon resonance (SPR) sensor is presented. In the transmission-type SPR structure, surface plasmon waves are outcoupled to radia-tion modes by the use of dielectric grating on a thin-film layer of Ag. Compared with the traditional reflection-type SPR sensor, the new method provides larger detectable range, which might be useful to investigate thick targets such as in cell analysis. Theoretical simulations show that the structures provide high transmission efficiency for surface plasmon resonance and the devices present extre-mely linear sensing characteristics. Furthermore, it is found that the transmission efficiency and the refractive index detection sensitivity of the SPR sensor can be improved by the use of a lower refractive index glass prism.

  4. Transmissive grating-reflective mirror-based fiber optic accelerometer for stable signal acquisition in industrial applications

    Science.gov (United States)

    Lee, Yeon-Gwan; Kim, Dae-Hyun; Kim, Chun-Gon

    2012-05-01

    This paper discusses an applicable fiber-optic accelerometer composed of a transmissive grating panel, a reflection mirror, and two optical fibers with a separation of quarter grating pitch as transceivers that monitor the low-frequency accelerations of civil engineering structures. This sensor structure brings together the advantages of both a simple sensor structure, which leads to simplified cable design by 50% in comparison with the conventional transmission-type fiber optic accelerometer, and a stable reflected signals acquisition with repeatability in comparison to the researched grating-reflection type fiber optic accelerometer. The vibrating displacement and sinusoidal acceleration measured from the proposed fiber optic sensor demonstrated good agreement with those of a commercial laser displacement sensor and a MEMS accelerometer without electromagnetic interference. The developed fiber optic accelerometer can be used in frequency ranges below 4.0 Hz with a margin of error that is less than 5% and a high sensitivity of 5.06 rad/(m/s)2.

  5. Electrically tunable transmission of gold binary-grating metasurfaces integrated with liquid crystals.

    Science.gov (United States)

    Chen, Kuo-Ping; Ye, Shi-Cheng; Yang, Chi-Yin; Yang, Zong-Han; Lee, Wei; Sun, Mao-Guo

    2016-07-25

    Planar photonics using metasurfaces is of great interest because a metasurface can control the flow of light beyond that attainable with natural materials. The resonance wavelength of a binary-grating metasurface is adjustable by changing the width and thickness of the nanostructure. We propose a novel combination of nematic liquid crystals and a binary-grating metasurface with which the diffraction efficiency can be controlled by adjusting the applied voltage. PMID:27464134

  6. Theoretical analysis of transmission characteristics for all fiber, multi-cavity Fabry-Perot filters based on fiber Bragg gratings

    Institute of Scientific and Technical Information of China (English)

    XU OU; LU ShaoHua; DONG XiaoWei; LI Bin; NING TiGang; JIAN ShuiSheng

    2008-01-01

    The characteristics of transmission spectra for the all fiber, multi-cavity FabryPerot (FP) configuration based on fiber Bragg gratings (FBG) are theoretically analyzed and modeled. The general transmission matrix function for the structure with any number of cavities is derived, and explicit expression of the power trans-mission coefficient for symmetrical two-cavity FP is presented. The general condi-tions for flat-top single resonant peak at the central wavelength in FBG stop band are derived and verified in the numerical simulation section. The transmission peaks of single-cavity and two-cavity FP structures are compared and discussed, and results show that compared to the single-cavity FP, flatness of the top and steepness at the edge of transmission peak can be improved by introducing one more cavity. The resonant transmission peak properties of two-cavity structure are investigated in detail for various values of cavity length and FBGs with different reflection characteristics, and the design guidelines for transmission-type filters are presented. The results show that the steepness of peak slope can be improved by increase of FBG reflectivities, and these kinds of filters can be used as nar-row-band single-channel selectors and multi-channel wavelength de-multiplexing by properly choosing the length of cavities and reflectivities of FBGs.

  7. Fabrication and characterization of free-standing, high-line-density transmission gratings for the vacuum UV to soft X-ray range

    OpenAIRE

    Goh, S. J.; Bastiaens, H.J.M.; Vratzov, B.; Huang, Q; Bijkerk, F.; Boller, K-J.

    2015-01-01

    We present state-of-the-art high resolution transmission gratings, applicable for spectroscopy in the vacuum ultraviolet (VUV) and the soft X-ray (SRX) wavelength range, fabricated with a novel process using ultraviolet based nano imprint lithography (UV-NIL). Free-standing, high-line-density gratings with up to 10,000 lines per mm and various space-to-period ratios were fabricated. An optical characterization of the gratings was carried out in the range from 17 to 34 nm wavelength using high...

  8. High-Resolution X-ray and Ultraviolet Spectroscopy of the Complex Intrinsic Absorption in NGC 4051 with Chandra and HST

    OpenAIRE

    Collinge, M. J.; Brandt, W. N.; Kaspi, Shai; Crenshaw, D. Michael; Elvis, Martin; Kraemer, Steven B.; Reynolds, Christopher S.; Sambruna, Rita M.; Wills, Beverley J.

    2001-01-01

    We present the results from simultaneous observations of the Narrow-Line Seyfert 1 galaxy NGC 4051 with the Chandra High Energy Transmission Grating Spectrometer and the HST Space Telescope Imaging Spectrograph. The X-ray grating spectrum reveals absorption and emission lines from hydrogen-like and helium-like ions of O, Ne, Mg and Si. We resolve two distinct X-ray absorption systems: a high-velocity blueshifted system at -2340+/-130 km/s and a low-velocity blueshifted system at -600+/-130 km...

  9. Chandra Observations of Variable Embedded X-ray sources in Orion. Paper I: Resolving Orion Trapezium

    OpenAIRE

    Schulz, N. S.; Canizares, C.; Huenemoerder, D.; Kastner, J.H.; Taylor, S. C.; Bergstrom, E. J.

    2000-01-01

    We used the High Energy Transmission Grating Spectrometer (HETGS) onboard the Chandra X-ray Observatory to perform two observations, separated by three weeks, of the Orion Trapezium region. The zeroth order images on the Advanced CCD Imaging Spectrometer (ACIS) provide spatial resolution of 0.5" and moderate energy resolution. Within a 160"x140" region around the Orion Trapezium we resolve 111 X-ray sources with luminosities between 7x10^{28} ergs/s and 2x10^{32} ergs/s. We do not detect any ...

  10. The Soft X-ray Spectrum from NGC 1068 Observed with LETGS on Chandra

    OpenAIRE

    Brinkman, A. C.; Kaastra, J.S.; Van Der Meer, R.L.J.; Kinkhabwala, A.; Behar, E; Kahn, S. M.; Paerels, F. B. S.; Sako, M.

    2002-01-01

    Using the combined spectral and spatial resolving power of the Low Energy Transmission Grating (LETGS) on board Chandra, we obtain separate spectra from the bright central source of NGC 1068 (Primary region), and from a fainter bright spot 4" to the NE (Secondary region). Both spectra are dominated by line emission from H- and He-like ions of C through S, and from Fe L-shell ions, but also include narrow radiative recombination continua, indicating that most of the soft X-ray emission arises ...

  11. A Deep Chandra X-ray Spectrum of the Accreting Young Star TW Hydrae

    OpenAIRE

    Brickhouse, N. S.; Cranmer, S. R.; Dupree, A. K.; Luna, G. J. M.; Wolk, S.

    2010-01-01

    We present X-ray spectral analysis of the accreting young star TW Hydrae from a 489 ks observation using the Chandra High Energy Transmission Grating. The spectrum provides a rich set of diagnostics for electron temperature T_e, electron density N_e, hydrogen column density N_H, relative elemental abundances and velocities and reveals its source in 3 distinct regions of the stellar atmosphere: the stellar corona, the accretion shock, and a very large extended volume of warm postshock plasma. ...

  12. Contemporaneous Chandra HETG and Suzaku X-ray Observations of NGC 4051

    OpenAIRE

    Lobban, AP; Reeves, JN; Miller, LL; Turner, TJ; Braito, V.; Kraemer, SB; Crenshaw, DM

    2011-01-01

    We present the results of a deep 300ks Chandra High Energy Transmission Grating (HETG) observation of the highly variable narrow-line Seyfert Type 1 galaxy NGC 4051. The HETG spectrum reveals 28 significant soft X-ray ionized lines in either emission or absorption; primarily originating from H-like and He-like K-shell transitions of O, Ne, Mg and Si (including higher order lines and strong forbidden emission lines from Ovii and Neix) plus high-ionization L-shell transitions from Fexvii to Fex...

  13. HDE 245059: A Weak-Lined T Tauri Binary Revealed by Chandra and Keck

    OpenAIRE

    Saavedra, C. Baldovin; Audard, M.; Duchêne, G.; Güdel, M.; Skinner, S.L.; Paerels, F. B. S.; Ghez, A.; McCabe, C.

    2009-01-01

    We present the Chandra High Energy Transmission Grating Spectrometer (HETGS) and Keck observations of HDE 245059, a young weak-lined T Tauri star (WTTS), member of the pre-main sequence group in the Lambda Orionis Cluster. Our high spatial resolution, near-infrared observations with Keck reveal that HDE 245059 a binary separated by 0.87". Based on this new information we have obtained an estimate of the masses of the binary components; 3M_{sun} and 2.5M_{sun} for the north and south component...

  14. Linear to radial/azimuthal polarization converter in transmission using form birefringence in a segmented silicon grating manufactured by high productivity microelectronic technologies

    Science.gov (United States)

    Kaempfe, T.; Sixt, P.; Renaud, D.; Lagrange, A.; Perrin, F.; Parriaux, O.

    2014-05-01

    A polarization rotation is realized by subwavelength binary gratings, where the TE and TM round trip phases of the smallest grating modes are fixed to the smallest possible integer numbers of 2π that allow a straight-through phase difference of π. This results in a subwavelength grating allowing to realize a half-wave element of almost 100% transmission. The principle is applied to a polarization transformation in the 1030-1064 nm wavelength range, using a segmented polarization rotating element converting a linearly polarized incidence to a radial or azimuthal polarization distribution. The elevated costs of such kind of polarization transformers based on assembled birefringent crystals are avoided by using mass-fabrication compatible silicon on insulator technology on a wafer scale. It shows the general potential of microelectronic technology, concerning the batch manufacturing of wavelength-scale diffractive, grating based elements for processing free space waves

  15. Influence of 4,4’-azobis (4-cyanopentanoic acid in Transmission and Reflection Gratings Stored in a PVA/AA Photopolymer

    Directory of Open Access Journals (Sweden)

    Elena Fernandez

    2016-03-01

    Full Text Available Holographic transmission gratings with a spatial frequency of 2658 lines/mm and reflection gratings with a spatial frequency of 4553 lines/mm were stored in a polyvinyl alcohol (PVA/acrylamide (AA based photopolymer. This material can reach diffraction efficiencies close to 100% for spatial frequencies about 1000 lines/mm. However, for higher spatial frequencies, the diffraction efficiency decreases considerably as the spatial frequency increases. To enhance the material response at high spatial frequencies, a chain transfer agent, the 4,4’-azobis (4-cyanopentanoic acid, ACPA, is added to the composition of the material. Different concentrations of ACPA are incorporated into the main composition of the photopolymer to find the concentration value that provides the highest diffraction efficiency. Moreover, the refractive index modulation and the optical thickness of the transmission and reflection gratings were obtained, evaluated and compared to procure more information about the influence of the ACPA on them.

  16. AEGIS: An Astrophysics Experiment for Grating and Imaging Spectroscopy---a Soft X-ray, High-resolution Spectrometer

    Science.gov (United States)

    Huenemoerder, David; Bautz, M. W.; Davis, J. E.; Heilmann, R. K.; Houck, J. C.; Marshall, H. L.; Neilsen, J.; Nicastro, F.; Nowak, M. A.; Schattenburg, M. L.; Schulz, N. S.; Smith, R. K.; Wolk, S.; AEGIS Team

    2012-01-01

    AEGIS is a concept for a high-resolution soft X-ray spectroscopic observatory developed in response to NASA's request for definitions of the next X-ray astronomy mission. At a small fraction of the cost of the once-planned International X-ray Observatory (IXO), AEGIS has capabilities that surpass IXO grating spectrometer requirements, and which are far superior to those of existing soft X-ray spectrometers. AEGIS incorporates innovative technology in X-ray optics, diffraction gratings and detectors. The mirror uses high area-to-mass ratio segmented glass architecture developed for IXO, but with smaller aperture and larger graze angles optimized for high-throughput grating spectroscopy with low mass and cost. The unique Critical Angle Transmission gratings combine low mass and relaxed figure and alignment tolerances of Chandra transmission gratings but with high diffraction efficiency and resolving power of blazed reflection gratings. With more than an order of magnitude better performance over Chandra and XMM grating spectrometers, AEGIS can obtain high quality spectra of bright AGN in a few hours rather than 10 days. Such high resolving power allows detailed kinematic studies of galactic outflows, hot gas in galactic haloes, and stellar accretion flows. Absorption line spectroscopy will be used to study large scale structure, cosmic feedback, and growth of black holes in thousands of sources to great distances. AEGIS will enable powerful multi-wavelength investigations, for example with Hubble/COS in the UV to characterize the intergalactic medium. AEGIS will be the first observatory with sufficient resolution below 1 keV to resolve thermally-broadened lines in hot ( 10 MK) plasmas. Here we describe key science investigations enable by Aegis, its scientific payload and mission plan. Acknowledgements: Support was provided in part by: NASA SAO contract SV3-73016 to MIT for the Chandra X-ray Center and Science Instruments; NASA grant NNX08AI62G; and the MKI

  17. Fabrication and characterization of free-standing, high-line-density transmission gratings for the vacuum UV to soft X-ray range

    NARCIS (Netherlands)

    Goh, S.J.; Bastiaens, H.J.M.; Vratzov, B.; Huang, Q.; Bijkerk, F.; Boller, K-J.

    2015-01-01

    We present state-of-the-art high resolution transmission gratings, applicable for spectroscopy in the vacuum ultraviolet (VUV) and the soft X-ray (SRX) wavelength range, fabricated with a novel process using ultraviolet based nano imprint lithography (UV-NIL). Free-standing, high-line-density gratin

  18. Single order X-ray diffraction with binary sinusoidal transmission grating

    Science.gov (United States)

    Cao, Leifeng

    2013-10-01

    All existing x-ray dispersive devices including crystals, multilayers and diffraction gratings generate spectra in multiple orders, whereas soft x-ray spectroscopy applications usually require only the first order spectrum. The other diffraction orders can overlap and contaminate the first order spectrum of interest. In this letter we describe how an axis-symmetrically-distributed sinusoidal-shaped aperture with binary transmittance values can be used to disperse x-rays and with a superior diffraction pattern where, along its symmetry axis, all higher-order diffractions can be effectively suppressed. Hence this sophisticated dispersive element generates pure soft x-ray spectra in the first diffraction order, free from interference from higher diffraction orders.

  19. Soft X-ray freestanding blazed transmission gratings%软X射线自支撑闪耀透射光栅

    Institute of Scientific and Technical Information of China (English)

    徐向东; 陈勇; 邱克强; 刘正坤; 付绍军

    2012-01-01

    To meet the requirements of the International X-ray Observatory (IXO), a new kind of diffraction grating called the soft X-ray freestanding blazed transmission grating, or critical-angle transmis- sion (CAT) grating, has been developed by the Massachusetts Institute of Technology team. The CAT grating has the advantages of both transmission and reflection gratings, while avoiding their disadvantages. Its basic concept, principle, and fabrication process are reviewed. Recent advances in this field are also presented.%软X射线自支撑闪耀透射光栅或临界角透射光栅是美国麻省理工学院为满足国际X射线天文台X射线光栅谱仪的科学要求而提出的一种新型衍射光栅,它集中了透射和反射光栅的优点,同时避免它们的缺点.文章对软x射线自支撑闪耀透射光栅的概念、基本原理、制作工艺进行了综述,介绍了美国麻省理工学院的光栅研制工作进展和文章作者的初步研究结果.

  20. Characterization of a quasi-sinusoidal transmission grating without membrane substrate in the 200-1500 eV photon energy regions

    Science.gov (United States)

    Wang, Chuanke; Wang, Baoqing; Yi, Tao; Fan, Quanping; Kuang, Longyu; Li, Jin; Li, Tingshuai; Zhu, Xiaoli; Liu, Shenye; Jiang, Gang

    2016-02-01

    A 1000-line/mm quasi-sinusoidal transmission grating (QSTG) without membrane substrate has been designed and fabricated, which is utilized to eliminate the higher order diffraction for soft X-ray spectrum measurement in the experiments of inertial confinement fusion. The grating was calibrated using an X-ray beam on synchrotron radiation facility. It shows that the QSTG has the desired diffraction property and the higher order diffraction components are efficiently suppressed in the photon energy ranges from 200 to 1500 eV.

  1. High-resolution X-ray spectroscopy of Procyon by Chandra and XMM-Newton

    CERN Document Server

    Raassen, A J J; Audard, M; Güdel, M; Behar, E; Kaastra, J S; Van der Meer, R L J; Foley, C R; Ness, J U

    2002-01-01

    We report the analysis of the high-resolution soft X-ray spectrum of the nearby F-type star Procyon in the wavelength range from 5 to 175 Angstrom obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board Chandra and with the Reflection Grating Spectrometers (RGS) and the EPIC-MOS CCD spectrometers on board XMM-Newton. Line fluxes have been measured separately for the RGS and LETGS. Spectra have been fitted globally to obtain self-consistent temperatures, emission measures, and abundances. The total volume emission measure is ~4.1 x 10e50/cm3 with a peak between 1 and 3 MK. No indications for a dominant hot component (T > 4 MK) were found. We present additional evidence for the lack of a solar-type FIP-effect, confirming earlier EUVE results.

  2. Upscaling of Helmholtz Equation Originating in Transmission through Metallic Gratings in Metamaterials

    Science.gov (United States)

    2016-01-01

    We investigate the transmission properties of a metallic layer with narrow slits. We consider (time-harmonic) Maxwell's equations in the H-parallel case with a fixed incident wavelength. We denote η > 0 as the typical size of the complex structure and obtain the effective equations by letting η → 0. For metallic permittivities with negative real part, plasmonic waves can be excited on the surfaces of the slits. For the waves to be in resonance with the height of the metallic layer, the corresponding results can be perfect transmission through the layer. PMID:27738650

  3. 准随机矩形孔阵列透射光栅%Qusia-random rectangular holes self-supporting transmission grating

    Institute of Scientific and Technical Information of China (English)

    刘钰薇; 曹磊峰; 张文海; 张继成; 范全平; 魏来; 晏卓阳; 赵屹东; 崔明启; 邱荣

    2015-01-01

    Support-mesh structures of a self-supporting transmission grating may decrease the transmission area and diffraction efficiency, thus exert a ill effect on the original diffraction pattern of the grating and make it complicated to apply, especially in soft X-ray region. To solve this problem, we put forward a method to realize a kind of totally self-supporting transmission grating by arranging the rectangular transmission holes in a high Z foil quasi-randomly. Based on Fraunhofer’s diffraction theory, we make a theoretical analysis on the diffraction pattern of this new kind of grating. We also calculate the diffraction pattern of this new kind of grating based on the Kirchhoff’s diffraction theory. Further more, we fabricate a sample grating of 1000 lines/mm using a focused ion beam (FIB) technology and then test it with the beam line 4B7B on the Beijing synchrotron radiation facility. Theoretical analysis and experimental result both show that the diffraction of the transmission grating can remove the ill effect of the support-mesh structures by using this newly designed method. Such a method can profit us in applications of this kind of X-ray dispersive element to a wide extent.%自支撑透射光栅的周期加强筋结构在降低光栅的通光面积、减少光栅衍射效率的同时,也影响了光栅原有的衍射模式,致使其应用更加复杂。为了应对这一问题,作者提出了利用在高Z材料薄膜上准随机排布矩形孔实现自支撑透射光栅的技术方法。理论分析与实验结果表明,利用新方法制作的透射光栅较好地摆脱了周期性加强筋对透射光栅衍射模式的强加干扰。

  4. Helium-like triplet density diagnostics: Applications to CHANDRA--LETGS X-ray observations of Capella and Procyon

    OpenAIRE

    Ness, J. U.; Mewe, R.; Schmitt, J. H. M. M.; Raassen, A. J. J.; Porquet, D.; Kaastra, J. S.; Van Der Meer, R.L.J.; Burwitz, V.; Predehl, P.

    2000-01-01

    Electron density diagnostics based on the triplets of Helium-like CV, NVI, and OVII are applied to the X-ray spectra of Capella and Procyon measured with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory. New theoretical models for the calculation of the line ratios between the forbidden (f), intercombination (i), and the resonance (r) lines of the helium-like triplets are used. The derived densities are quite typical of densities found in the sol...

  5. High-resolution transmission electron microscopy studies of quantum wire structures grown on submicrometre gratings of V-grooves

    Science.gov (United States)

    Gustafsson, A.; Malm, J.-O.; Carlsson, A.; Vermeire, G.

    1996-11-01

    We present an extensive characterization of a quantum wire (QWR) structure using transmission electron microscopy (TEM). The structure consisted of a single GaAs layer in between AlGaAs barriers, grown on a GaAs substrate patterned with a submicrometre grating of V-grooves. For reference we also studied other QWR, as well as, quantum well (QW) samples, fabricated under similar conditions. We used bright field and dark field imaging to study the overall structure, high-resolution TEM to study the layer thickness and the interface quality, and chemical lattice imaging to study the compositional variations across the interfaces. In the QWR sample, there were mainly two distinctly different areas of the QW: on the (100) planes between the V-grooves, the QW was flat, whereas the QW on the near 0268-1242/11/11/018/img5 side walls of the V-grooves had a flat lower interface and a saw-tooth shaped upper interface. The QWRs at the bottom of the V-grooves were crescent shaped. We also observed a fundamental difference in growth of the GaAs and the AlGaAs on the side wall, where the AlGaAs formed straight interfaces, determined by high-index planes, whereas the GaAs tended to form alternating low-index planes giving a saw-tooth appearance of the GaAs QW.

  6. Transmission Grating Measuring System in X-ray Wavelength%软X射线波段透射光栅检测系统

    Institute of Scientific and Technical Information of China (English)

    李旭; 何飞; 陈波

    2012-01-01

    目前,透射光栅被广泛地应用于软X射线波段光谱测量当中.但由于在软X射线波段几乎所有材料都有非常明显的吸收,因此利用传统方法很难在该波段对透射光栅进行检测.为了检测透射光栅在软X射线波段的光谱分辨本领,我们基于掠入射理论,采用凹面反射光栅单色仪配X射线CCD相机组成一套软X射线波段透射光栅检测装置.首先利用He空心阴极光源的30.38nm、53.70nm和58.43nm三条线谱对透射光栅检测系统进行波长标定.然后更换激光等离子体光源,测量并得到了金自支撑式透射光栅在6.67nm和9.10nm两个波长位置上一级衍射位置和一级衍射光谱线宽度,利用半宽度法计算并得出在以上两个波长位置时被测透射光栅一级谱所能分辨的最小波长差为2.38nm和2.05nm.实验结果表明该投射光栅检测系统完全可以应用于软X射线波段透射光栅检测工作当中.%Transmission gratings have been widely used in spectrummeasurements in soft X-ray wavelength.But it is too difficulty to measure the transmission grating in traditionmethod . Because the most of materials have much absorbtion in X-ray wavelength.A transmission grating measuring system that is composed by concave reflective gratingmonochromator and X-ray CCD camera is setup to test the spectrum resolution of transmission grating in soft X-ray wavelength. Three lines of 30.38nm, 53.70nm and 58.43nm from Helium hollow cathode source are used first to calibrate the wavelength of the transmission gratingmeasuring system. Then the first-order relative spectrum resolution of the golden self-supporting type transmission grating at 6.67nm and 9.10nm are measured with laser plasma source. According to the experimental results, using half-widthmethod, the distinguishableminimum wavelength differences of the first-order spectra of the golden transmission grating aremeasured to be 2.38nm and 2.05nm respectively at the two wavelengths

  7. A Phase-shifted Chirped Fiber Bragg Grating with Dual-wavelength Transmission%双波长啁啾相移光纤光栅

    Institute of Scientific and Technical Information of China (English)

    陈金林; 孙军强; 夏利; 刘爽

    2009-01-01

    理论研究并实验验证了一种含有两段π相移的啁啾相移光纤光栅.采用F矩阵对啁啾相移光纤光栅进行计算并分析了该光栅的谱特性.含有两段π相移的啁啾相移光纤光栅可以在普通啁啾光栅透射谱阻带中产生双波长透射峰,透射峰位置直接取决于光栅中π相移的位置,透射峰的线宽和透射峰的波长间隔没有关系,仅随着啁啾率的增大而增大.采用带相位掩模的逐点扫描法对含有两段π相移的双波长啁啾相移光栅进行了制作,获得波长间隔为8 nm的双波长透射谱的光栅器件.该光栅的消光比和3 dB谱线宽分别为20 dB和0.08 nm,实验结果和理论设计一致.%A phase-shifted chirped fiber Bragg grating with two π phase shifts was studied theoretically and experimentally.The grating was calculated by F matrix,based on which the properties of the spectra were analyzed.The phase-shifted chirped fiber Bragg grating has a transmission spectrum with dual-wavelength peaks.The wavelength position of the peaks is directly dependent on the position of the π phase shifts.The linewidth of the peaks increases only with the chirp of the grating,and is not related with the wavelength difference of the two peaks.Due to the local character of chirped fiber gratings,the design of the phase-shifted chirped fiber Bragg gratings is simple.A phase-shifted chirped fiber Bragg grating with two π phase shifts was fabricated by ultraviolet scanning with a phase mask.The wavelength difference,the extinction ratio,and the 3dB linewidth of the two peaks in the transmission spectrum are 8nm,20dB and 0.08nm,respectively,which agree with the theoretical design.

  8. Dynamics of the Shocked Gas in the Eta Carinae System as Seen by Chandra

    Science.gov (United States)

    Corcoran, M. F.; Hamaguchi, K.; Henley, D. B.; Ishibashi, K.; Gull, T.; Nielsen, K.; Pittard, J. M.

    2006-01-01

    We report on a series of X-ray spectra of the supermassive star Eta Carinae obtained by the High Energy Transmission Grating Spectrometer on the CHANDRA X-ray observatory before, during and after the star's X-ray minimum in the summer of 2003. The X-ray spectra show significant variations in emission measure and absorption, in the strength of the iron K edge and fluorescent iron emission, but show little change in the distribution of emission measure with temperature. The CHANDRA spectra also resolve emission from Si, S, Fe and other elements in H-like and He-like configurations. The HETGS spectra show that these lines change in centroid energy along with evidence of changes in the forbidden-to-intercombination ratios of the He-like triplets. These spectra offer strong support that the X-ray emission originates within a shock cone around an unseen, massive companion. The variations of the X-ray line spectrum provide a direct measure of the dynamics of the shocked gas in this cone and also evidence that the hottest region of the shock is not always in collisional ionization equilibrium. We discuss these results in light of the recent discovery of He II 4686 emission and the reported discovery of FUV emission from the companion star. This work was supported by SAO/Chandra grant GO3-4008A.

  9. HDE 245059: A Weak-Lined T Tauri Binary Revealed by Chandra and Keck

    CERN Document Server

    Saavedra, C Baldovin; Duchêne, G; Güdel, M; Skinner, S L; Paerels, F B S; Ghez, A; McCabe, C

    2009-01-01

    We present the Chandra High Energy Transmission Grating Spectrometer (HETGS) and Keck observations of HDE 245059, a young weak-lined T Tauri star (WTTS), member of the pre-main sequence group in the Lambda Orionis Cluster. Our high spatial resolution, near-infrared observations with Keck reveal that HDE 245059 a binary separated by 0.87". Based on this new information we have obtained an estimate of the masses of the binary components; 3M_{sun} and 2.5M_{sun} for the north and south components, respectively. We have estimated the age of the system to be ~2-3 Myr. We detect both components of the binary in the zeroth order Chandra image and in the grating spectra. Our fits to the spectrum of the binary have shown that the emission is dominated by a plasma between 8 and 15 MK, a soft component at 4 MK and a hard component at 50 MK are also detected. The value of the hydrogen column density was low, 8 x 10^{19} cm^{-2}, likely due to the clearing of the inner region of the Lambda Orionis cloud. The abundance pat...

  10. High-Resolution Chandra X-ray Imaging and Spectroscopy of the Sigma Orionis Cluster

    CERN Document Server

    Skinner, S L; Cohen, D H; Gagné, M; Owocki, S P; Townsend, R D

    2008-01-01

    We present results of a 90 ksec Chandra X-ray observation of the young sigma Orionis cluster (age ~3 Myr) obtained with the High Energy Transmission Grating Spectrometer. We use the high resolution grating spectrum and moderate resolution CCD spectrum of the massive central star sigma Ori AB (O9.5V + B0.5V) to test wind shock theories of X-ray emission and also analyze the high spatial resolution zero-order ACIS-S image of the central cluster region. Chandra detected 42 X-ray sources on the primary CCD (ACIS-S3). All but five have near-IR or optical counterparts and about one-fourth are variable. Notable high-mass stellar detections are sigma Ori AB, the magnetic B star sigma Ori E, and the B5V binary HD 37525. Most of the other detections have properties consistent with lower mass K or M-type stars. We present the first X-ray spectrum of the unusual infrared source IRS1 located 3.3 arc-sec north of sigma Ori AB, which is likely an embedded T Tauri star whose disk/envelope is being photoevaporated by sigma Or...

  11. Surface-plasmon-enhanced light transmission intensity with a basic grating in GaN-based LED

    International Nuclear Information System (INIS)

    The transmitting light in GaN-based LED with 30 nm thickness metal film grating is investigated. We proposed a basic grating structure model to enhance light intensity in GaN material, which was simpler and cheaper. We calculated and analyzed the structure with different parameters, and studied the numerical simulation results of Ag-films/Al-films/Au-films. With a simple Al or Ag basic grating structure, the 7.4–7.6 times intensity of 550 nm light can be obtained easily, and the enhancement efficiency is better than others. (semiconductor materials)

  12. Chandra and XMM-Newton view of the warm absorbing gas in Mrk 290

    Science.gov (United States)

    Zhang, S. N.; Ji, L.; Marshall, H. L.; Longinotti, A. L.; Evans, D.; Gu, Q. S.

    2011-02-01

    We present a detailed analysis of the Chandra High Energy Transmission Grating Spectrometer (HETGS) and XMM-Newton high-resolution spectra of the bright Seyfert 1 galaxy, Mrk 290. The Chandra HETGS spectra reveal complex absorption features that can be best described by a combination of three ionized absorbers. The outflow velocities of these warm absorbers are about 450 km s-1, consistent with the three absorption components found in a previous far-UV study. The ionizing continuum of Mrk 290 fluctuated by a factor of 1.4 during Chandra observations on a time-scale of 17 d. Using the response in opacity of the three absorbers to this fluctuation, we put a lower limit on the distance from the ionizing source of 0.9 pc for the medium ionized absorber and an upper limit on a distance of 2.5 pc for the lowest ionized absorber. The three ionization components lie on the stable branch of the thermal equilibrium curve, indicating roughly the same gas pressure. Therefore, the thermal wind from the torus is most likely the origin of warm absorbing gas in Mrk 290. During the XMM-Newton observation, the ionizing luminosity was 50 per cent lower compared to that in the Chandra observation. The Reflection Grating Spectrometer spectrum is well fitted by a two-phase warm absorber, with several additional absorption lines attributed to a Galactic high-velocity cloud, complex C. Neither the ionization parameter ξ nor the column density NH of the two absorbing components varied significantly, compared to the results from Chandra observations. The outflow velocities of both components were 1260 km s-1. We suggest that an entirely new warm absorber from the torus passed through our line of sight. Assuming the torus wind model, the estimated mass outflow rate is ˜0.1 M⊙ per year while the nuclear accretion rate is ˜0.04 M⊙ per year. The O VII and Ne IX forbidden lines are the most prominent soft X-ray emission lines, with a mean redshift of 700 km s-1 relative to the systematic

  13. Chandra Examines Black Holes Large and Small in Nearby Galaxy

    Science.gov (United States)

    2001-05-01

    's supermassive black hole." On astronomical scales, this galaxy is considered quite close, a mere13 million light years from Earth. Since it’s located near the plane of our own Milky Way Galaxy, the Circinus galaxy is partially hidden by intervening dust along our line of sight. As a result, the galaxy went unnoticed until about 25 years ago. Along with Sambruna and Bauer, the first research group included Hagai Netzer of Tel-Aviv University and the following collaborators from Penn State: Niel Brandt, George Chartas, Gordon Garmire, John Nousek, and Shai Kaspi. The University of Maryland team also included Andrew Wilson. The results of theses Chandra observations appear in recent and upcoming papers in The Astrophysical and Astronomical Journals. Observations with Chandra, using the Advanced CCD Imaging Spectrometer (ACIS) and the High Energy Transmission Grating Spectrometer (HETGS), were made on June 6-7, 2000 and observations without the HETGS were made on March 14, 2000. The HETG and ACIS instruments were built for NASA by the Massachusetts Institute of Technology, Cambridge, MA, and Pennsylvania State University, University Park. NASA's Marshall Space Flight Center, Huntsville, AL, manages the Chandra program for the Office of Space Science, Washington, DC. TRW, Inc., Redondo Beach, California, is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, MA. Images associated with this release are available on the World Wide Web at: http://chandra.harvard.edu AND http://chandra.nasa.gov

  14. Interstellar X-ray Absorption Spectroscopy of Oxygen, Neon, and Iron with the Chandra LETGS Spectrum of X0614+091

    CERN Document Server

    Paerels, F B S; Van der Meer, R L J; Kaastra, J S; Kuulkers, E; Den Boggende, A J F; Predehl, P; Drake, J J; Kahn, S M; Savin, D W; McLaughlin, B M; Paerels, Frits; Drake, Jeremy J.; Kahn, Steven M.; Savin, Daniel W.; Laughlin, Brendan M. Mc

    2000-01-01

    We find resolved interstellar O K, Ne K, and Fe L absorption spectra in the Chandra Low Energy Transmission Grating Spectrometer spectrum of the low mass X-ray binary X0614+091. We measure the column densities in O and Ne, and find direct spectroscopic constraints on the chemical state of the interstellar O. These measurements probably probe a low-density line of sight through the Galaxy and we discuss the results in the context of our knowledge of the properties of interstellar matter in regions between the spiral arms.

  15. Chandra view of the warm-hot intergalactic medium toward 1ES 1553+113: Absorption-line detections and identifications. I

    OpenAIRE

    F. Nicastro; Barcons, Xavier; Paerels, F. B. S.

    2013-01-01

    We present the first results from our pilot 500 ks Chandra Low Energy Transmission Grating Large Program observation of the soft X-ray brightest source in the z ≳ 0.4 sky, the blazar 1ES 1553+113, aimed to secure the first uncontroversial detections of the missing baryons in the X-rays. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2σ and 4.1σ. Six of these lines are detected at high single-line statistical significance (3.6 ≤ σ ≤ 4....

  16. Diffraction efficiencies of holographic laminar and blazed types gratings for use in a flat-field spectrograph in the 50-200 eV range for transmission electron microscopes

    Science.gov (United States)

    Imazono, T.; Koike, M.; Kawachi, T.; Koeda, M.; Nagano, T.; Sasai, H.; Oue, Y.; Yonezawa, Z.; Kuramoto, S.; Sano, K.

    2011-09-01

    A versatile soft x-ray flat-field grating spectrograph to be installed to a conventional transmission electron microscope has been developed. A holographic spherical grating of a 1200-lines/mm effective groove density which places emphasis on the low energy region of 50-200 eV is designed by an aspheric wavefront recording system. Laminar and blazed types master (LM and BM) gratings and their respective replica (LR and BR) gratings are fabricated by holographic exposure and ion-beam etching methods. Absolute diffraction efficiencies in the 50-300 eV range at the angle of incidence of 86.0 degrees were measured using a synchrotron radiation. The first order diffraction efficiencies are 6.1-7.5% (or 12%) for LM (or BM) and 7.4-9.6% (or 13%) for LR (or BR) gratings at near 55 eV, and over 5% (or 8%) in the 50-200 eV range for LM and LR (or BM and BR) gratings. The replica gratings show the comparable first-order diffraction efficiencies with their respective laminar and blazed types of master gratings.

  17. Research on tunable phase shift induced by piezoelectric transducer in linearly chirped fiber Bragg grating with the V-I transmission matrix formalism

    Science.gov (United States)

    Wu, Liangying; Pei, Li; Liu, Chao; Wang, Jianshuai

    2016-05-01

    In this study, the V-I transmission matrix (V-I TM) is proposed to analyze the tunable single phase shift (SPS) and multiple phase shifts (MPS) inserted in a linearly chirped fiber Bragg grating (LCFBG). According to the simulation results, the peaks appear on the transmission spectrum, when the phase shifts are induced in the LCFBG. With the increase of the phase shift, the center wavelength of the peak moves toward long wavelength region. A remarkable degree of bilateral symmetry can be found as characteristic of the depth of peaks. The maximum depth caused by inserted π-shift is the symmetric axis. Moreover, when MPS are inserted simultaneously, the appeared peaks are independent and the variation tendency of each peak is the same with that caused by SPS. The experiment of phase shift induced by a piezoelectric transducer (PZT) verifies the correctness of the simulation, and a narrow bandwidth of 0.028 nm is acquired.

  18. Characteristics of the transmission spectrum of the long period fiber gratings based on the coupling of core mode to the higher order cladding modes

    Institute of Scientific and Technical Information of China (English)

    Zijia Zhang(张自嘉); Wenkang Shi(施文康)

    2003-01-01

    The characteristics of the transmission spectrum of the Long-period fiber gratings (LPFGs) based on thecoupling of core mode to a higher order cladding mode (HE mode) are investigated using the coupled modetheory. This kind of LPFGs is different from that based on the coupling of core mode to a lower ordercladding mode because of the effect of the coupling of core mode to EH cladding mode. When the claddingmode order is higher, the coupling coefficients of core mode to HE and EH cladding modes are comparableand both of the propagation constants of HE and EH cladding modes approach, so the spectrum has anadditional loss peak. The bandwidth of LPFG based on the coupling of core mode to different claddingmode differs greatly. With the change of the mode orders from lower to higher, the transmission spectrumchanges from narrow to wide and more narrow.

  19. The origin of emission and absorption features in Ton S180 Chandra observations

    CERN Document Server

    nska, A R; Siemiginowska, A L; Dumont, A M; Kawaguchi, T

    2004-01-01

    We present new interpretation of Ton S180 spectrum obtained by {\\it Chandra} Spectrometer (Low Energy Transmission Grating). Several narrow absorption lines and a few emission disk lines have been successfully fitted to the data. We have not found any significant edges accompanying line emission. We propose the interpretation of narrow lines consistent with the paper recently written by Krolik (2002), where warm absorber is strongly inhomogeneous. Such situation is possible in so called multi-phase medium, where regions with different ionization states, densities and temperatures may coexist in thermal equilibrium under constant pressure. We illustrate this scenario with theoretical spectra of radiation transfered through a stratified cloud with constant pressure (instead of constant density) computed by code {\\sc titan} in plane parallel approximation. Detected spectral features are faint and their presence do not alter the broad band continuum. We model the broad band continuum of Ton S180 assuming an irrad...

  20. A Deep Chandra X-ray Spectrum of the Accreting Young Star TW Hydrae

    CERN Document Server

    Brickhouse, N S; Dupree, A K; Luna, G J M; Wolk, S

    2010-01-01

    We present X-ray spectral analysis of the accreting young star TW Hydrae from a 489 ks observation using the Chandra High Energy Transmission Grating. The spectrum provides a rich set of diagnostics for electron temperature T_e, electron density N_e, hydrogen column density N_H, relative elemental abundances and velocities and reveals its source in 3 distinct regions of the stellar atmosphere: the stellar corona, the accretion shock, and a very large extended volume of warm postshock plasma. The presence of Mg XII, Si XIII, and Si XIV emission lines in the spectrum requires coronal structures at ~10 MK. Lower temperature lines (e.g., from O VIII, Ne IX, and Mg XI) formed at 2.5 MK appear more consistent with emission from an accretion shock. He-like Ne IX line ratio diagnostics indicate that T_e = 2.50 +/- 0.25 MK and N_e = 3.0 +/- 0.2 x 10^(12) cm^(-3) in the shock. These values agree well with standard magnetic accretion models. However, the Chandra observations significantly diverge from current model pred...

  1. The Chandra/HETG view of NGC 1365 in a Compton-thick state

    CERN Document Server

    Nardini, E; Reeves, J N; Braito, V; Risaliti, G; Costa, M

    2015-01-01

    We present the analysis of a Chandra High-Energy Transmission Grating (HETG) observation of the local Seyfert galaxy NGC 1365. The source, well known for its dramatic X-ray spectral variability, was caught in a reflection-dominated, Compton-thick state. The high spatial resolution afforded by Chandra allowed us to isolate the soft X-ray emission from the active nucleus, neglecting most of the contribution from the kpc-scale starburst ring. The HETG spectra thus revealed a wealth of He- and H-like lines from photoionized gas, whereas in larger aperture observations these are almost exclusively produced through collisional ionization in the circumnuclear environment. Once the residual thermal component is accounted for, the emission-line properties of the photoionized region close to the hard X-ray continuum source indicate that NGC 1365 has some similarities to the local population of obscured active galaxies. In spite of the limited overall data quality, several soft X-ray lines seem to have fairly broad prof...

  2. The First Chandra Field

    Energy Technology Data Exchange (ETDEWEB)

    Weisskopf, Martin C.; /NASA, Marshall; Aldcroft, Thomas L.; /Harvard-Smithsonian Ctr. Astrophys.; Cameron, Robert A.; /Harvard-Smithsonian Ctr. Astrophys. /SLAC; Gandhi,; Foellmi, Cedric; /European Southern Obs., Chile; Elsner, Ronald F.; /NASA, Marshall; Patel, Sandeep K.; /USRA, Huntsville; Wu, Kinwah; /Mullard Space Sci. Lab.; O' Dell, Stephen; /NASA, Marshall

    2005-09-09

    Before the official first-light images, the Chandra X-ray Observatory obtained an X-ray image of the field to which its focal plane was first exposed. We describe this historic observation and report our study of the first Chandra field. Chandra's Advanced CCD Imaging Spectrometer (ACIS) detected 15 X-ray sources, the brightest being dubbed ''Leon X-1'' to honor the Chandra Telescope Scientist, Leon Van Speybroeck. Based upon our analysis of the X-ray data and spectroscopy at the European Southern Observatory (ESO; La Silla, Chile), we find that Leon X-1 is a Type-1 (unobscured) active galactic nucleus (AGN) at a redshift z = 0.3207. Leon X-1 exhibits strong Fe II emission and a broad-line Balmer decrement that is unusually flat for an AGN. Within the context of the Eigenvector-1 correlation space, these properties suggest that Leon X-1 may be a massive ({ge} 10{sup 9} M{sub {circle_dot}}) black hole, accreting at a rate approaching its Eddington limit.

  3. Design and Operation of a Frequency Doubled Nd:YAG Thomson Scattering System with Transmission Grating ICCD Spectrometer

    Science.gov (United States)

    Schoenbeck, N. L.; Dowd, A. S.; Fonck, R. J.; Schlossberg, D. J.; Winz, G. R.

    2012-10-01

    A novel Thomson scattering system has been deployed on the Pegasus Toroidal Experiment. It provides a relatively low-cost, simplified design. Scattering is achieved using a 7 ns, 2 J frequency doubled Nd:YAG laser operating at 532 nm. The laser focuses to ˜3 mm diameter within the plasma via a 7 m beam-line. The beam-line contains cameras as beam finders and remotely adjustable mirrors for shot-to-shot alignment. A custom multi-element lens collects scattered photons from 15 cm 40%) image intensified CCD (ICCD) camera. Three spectrometers provide a total of 24 channels. Two interchangeable gratings exist to cover low (Te = 10--100 eV) and high (Te = 0.10--1 keV) electron temperature regimes on Pegasus. The spectrometer is optimized for ne from mid-10^18 to mid-10^19 m-3. The signal-to-noise expected is ˜0.5 of an equivalent system using Nd:YAG at 1064 nm and avalanche photodiode detectors.

  4. Ten Years of Chandra

    Science.gov (United States)

    Weisskopf, Martin C.

    2009-01-01

    We celebrated the 10-th anniversary of the Launch of the Chandra X-ray Observatory on July 13, 2009. During these 10 years data from this Great Observatory have had a profound impact on 21st century astrophysics. With its unrivaled capability to produce sub-arcsecond images, the Observatory has enabled astronomers to make new discoveries in topics as diverse as comets and cosmology. We shall review some of the highlights, discuss the current status, and future plans.

  5. An X-ray look at the Seyfert 1 Galaxy Mrk 590: XMM-Newton and Chandra reveal complexity in circumnuclear gas

    CERN Document Server

    Longinotti, A L; Santos-Lleó, M; Rodriguez-Pascual, P; Guainazzi, M; Cardaci, M; Pollock, A M T

    2007-01-01

    This paper reports on a partially simultaneous observation of the bright Seyfert 1 Galaxy Mrk590, performed by XMM-Newton and Chandra. The long exposure (~100 ks) allows to investigate with great detail the Fe K complex at 6-7 keV and the presence of soft X-ray spectral features. We have analysed XMM-Newton data from the European Photon Imaging Camera (EPIC) in the 0.5-12 keV band and from the Reflection Grating Spectrometer (RGS) in the 0.35-2.5 keV band, and data from the High Energy Transmission Gratings (HETGs) onboard Chandra. UV and optical data from the Optical Monitor (OM) onboard XMM-Newton are also included in the analysis. The broad band spectrum is well described by an unabsorbed power law and three unresolved Fe~K lines in the 6-7 keV range. The presence of a Compton reflection component and a narrow Fe K line at 6.4 keV is consistent with an origin via torus reflection. The ionised Fe lines at ~6.7 and 7 keV are instead most likely originated by scattering on a warm and ionised gas. The soft X-r...

  6. Experimental calibration of transmission grating and theoretical calculation of diffraction efficiency%透射光栅的实验标定和衍射效率的理论模拟

    Institute of Scientific and Technical Information of China (English)

    尚万里; 杨家敏; 赵屹东; 崔明启; 郑雷; 韩勇; 周克瑾; 马陈燕; 朱托; 熊刚; 赵阳; 张文海; 易荣清; 况龙钰; 曹磊峰; 高宇林

    2011-01-01

    透射光栅广泛应用于软X射线能谱测量.为了获得用于惯性约束聚变研究的透射光栅的各级衍射效率及其他参数,在北京同步辐射源上200-1600eV能量范围内对其进行了标定,获得了透射光栅衍射效率的实验结果.扩展了透射光栅衍射效率的计算方法,提出了7边准梯形截面衍射效率计算模型.分析拟合了实验数据,理论结果与实验结果很好符合.得到了7边准梯形的透射光栅栅线截面结构.%Transmission grating is widely used in measurement of soft X rays. In order to measure the diffraction efficiencies of the transmission grating which is used in laser fusion, the transmission grating was calibrated on Beijing Synchrotron Radiation Facility in the energy region from 200eV to 1600eV, and the experimental results have been obtained. The model for grating efficiency simulation has been developed and calculations using a new so called 7-side quasi-trapezoidal cross section model were carried out. The results from the new model are in good agreement with the experimental data.The exact grating wire cross section is described.

  7. Galaxy Clusters with Chandra

    CERN Document Server

    Forman, W; Markevitch, M L; Vikhlinin, A A; Churazov, E

    2002-01-01

    We discuss Chandra results related to 1) cluster mergers and cold fronts and 2) interactions between relativistic plasma and hot cluster atmospheres. We describe the properties of cold fronts using NGC1404 in the Fornax cluster and A3667 as examples. We discuss multiple surface brightness discontinuities in the cooling flow cluster ZW3146. We review the supersonic merger underway in CL0657. Finally, we summarize the interaction between plasma bubbles produced by AGN and hot gas using M87 and NGC507 as examples.

  8. Lunar Prospecting With Chandra

    Science.gov (United States)

    2003-09-01

    Observations of the bright side of the Moon with NASA's Chandra X-ray Observatory have detected oxygen, magnesium, aluminum and silicon over a large area of the lunar surface. The abundance and distribution of those elements will help to determine how the Moon was formed. "We see X-rays from these elements directly, independent of assumptions about the mineralogy and other complications," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., at a press conference at the "Four Years with Chandra" symposium in Huntsville, Alabama. "We have Moon samples from the six widely-space Apollo landing sites, but remote sensing with Chandra can cover a much wider area," continued Drake. "It's the next best thing to being there, and it's very fast and cost-effective." The lunar X-rays are caused by fluorescence, a process similar to the way that light is produced in fluorescent lamps. Solar X-rays bombard the surface of the Moon, knock electrons out of the inner parts of the atoms, putting them in a highly unstable state. Almost immediately, other electrons rush to fill the gaps, and in the process convert their energy into the fluorescent X-rays seen by Chandra. According to the currently popular "giant impact" theory for the formation of the Moon, a body about the size of Mars collided with the Earth about 4.5 billion years ago. This impact flung molten debris from the mantle of both the Earth and the impactor into orbit around the Earth. Over the course of tens of millions of years, the debris stuck together to form the Moon. By measuring the amounts of aluminum and other elements over a wide area of the Moon and comparing them to the Earth's mantle, Drake and his colleagues plan to help test the giant impact hypothesis. "One early result," quipped Drake, "is that there is no evidence for large amounts of calcium, so cheese is not a major constituent of the Moon." Illustration of Earth's Geocorona Illustration of Earth's Geocorona The same

  9. 10Gb/s transmission over 100 km of standard single-mode fiber with a dispersion tunable chirped fiber grating

    Institute of Scientific and Technical Information of China (English)

    秦子雄; 杜卫冲; 曾庆科; 刘宁; 郭旗; 廖常俊; 刘颂豪; 孙健; 陈雪; 蔡连峰; 余重秀

    1999-01-01

    A simple strain method is used to change uniform gratings into chirped gratings. The correspondent theory is presented. It is deduced that the product of the maximum bandwidth and the corresponding dispersion is nearly equal to a constant. The dispersion compensation distance for standard single-mode fiber G. 652, 10 Gb/s systems over 100 km is realized by using this method.

  10. Chandra Finds Oxygen and Neon Ring in Ashes of Exploded Star

    Science.gov (United States)

    2000-01-01

    NASA's Chandra X-ray Observatory has revealed an expanding ring-like structure of oxygen and neon that was hurled into space by the explosion of a massive star. The image of E0102-72 provides unprecedented details about the creation and dispersal of heavy elements necessary to form planets like Earth. The results were reported by Professor Claude Canizares of the Massachusetts Institute of Technology (MIT), Cambridge, at the 195th national meeting of the American Astronomical Society in Atlanta, Ga. Drs. Kathryn Flanagan, David Davis, and John Houck of MIT collaborated with Canizares in this investigation. E0102-72 is the remnant of a supernova explosion located in our neighbor galaxy, the Small Magellanic Cloud, nearly 200,000 light years away. It was created by the explosion of a star that was more than ten times as massive as our Sun. We are seeing the aftermath of the explosion a thousand or more years after the outburst. Shock waves are heating gas to temperatures of nearly 10 million degrees, so it glows with X-rays that are detected by Chandra's instruments. By using the High Energy Transmission Grating Spectrometer (HETG), astronomers were able to pinpoint the distribution of each chemical element individually and measure the velocities of different parts of the expanding ring. They also show the shock wave in a kind of "freeze-frame," revealing the progressive heating of the stellar matter as it plows into the surrounding gas. This is the first time such detailed X-ray information has ever been obtained for a supernova remnant, and should provide critical clues to the nature of supernovas. The grating spectrometer, which was built by an MIT team led by Canizares, spreads the X-rays according to their wavelength, giving distinct images of the object at specific wavelengths characteristic of each chemical element. Small wavelength shifts caused by the Doppler effect are used to measure the expansion velocities of each element independently. "We've been

  11. New Results from Chandra

    CERN Document Server

    Forman, W; Jones, C; Vikhlinin, A A; Churazov, E

    2001-01-01

    We discuss two themes from Chandra observations of galaxies and clusters. First, we describe the effects of radio-emitting plasmas or ``bubbles'', inflated by active galactic nuclei, on the hot X-ray emitting gaseous atmospheres in galaxies and clusters. We describe the interaction of the ``bubbles'' and the X-ray emitting gas as the buoyant bubbles rise through the hot gas. Second, we describe sharp, edge-like surface brightness structures in clusters. Chandra observations show that these features are not shock fronts as was originally thought, but ``cold fronts'', most likely the boundaries of the remaining cores of merger components. Finally, we present recent observations of M86 and NGC507 which show similar sharp features around galaxies. For M86, the sharp edge is the boundary between the galaxy's X-ray corona and the Virgo cluster gas. The structures around NGC507, the central galaxy in a group, could be relics of galaxy formation or may reflect the motion of NGC507 in the larger potential of the group...

  12. Fabrication of large area plasmonic nanoparticle grating structure on silver halide based transmission electron microscope film and its application as a surface enhanced Raman spectroscopy substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Singh, M. N.; Sinha, A. K.; Rai, V. N.; Srivastava, A. K. [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India); Bhartiya, S. [Laser Material Development and Device Division, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India); Mukherjee, C. [Mechanical and Optical Support Section, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India)

    2015-08-14

    The plasmonic responses of silver nanoparticle grating structures of different periods made on silver halide based electron microscope film are investigated. Raster scan of the conventional scanning electron microscope (SEM) is used to carry out electron beam lithography for fabricating the plasmonic nanoparticle grating (PNG) structures. Morphological characterization of the PNG structures, carried out by the SEM and the atomic force microscope, indicates that the depth of the groove decreases with a decrease in the grating period. Elemental characterization performed by the energy dispersive spectroscopy and the x-ray diffraction shows the presence of nanoparticles of silver in the PNG grating. The optical characterization of the gratings shows that the localized surface plasmon resonance peak shifts from 366 to 378 nm and broadens with a decrease in grating period from 10 to 2.5 μm. The surface enhanced Raman spectroscopy of the Rhodamine-6G dye coated PNG structure shows the maximum enhancement by two orders of magnitude in comparison to the randomly distributed silver nanoparticles having similar size and shape as the PNG structure.

  13. Fabrication of large area plasmonic nanoparticle grating structure on silver halide based transmission electron microscope film and its application as a surface enhanced Raman spectroscopy substrate

    International Nuclear Information System (INIS)

    The plasmonic responses of silver nanoparticle grating structures of different periods made on silver halide based electron microscope film are investigated. Raster scan of the conventional scanning electron microscope (SEM) is used to carry out electron beam lithography for fabricating the plasmonic nanoparticle grating (PNG) structures. Morphological characterization of the PNG structures, carried out by the SEM and the atomic force microscope, indicates that the depth of the groove decreases with a decrease in the grating period. Elemental characterization performed by the energy dispersive spectroscopy and the x-ray diffraction shows the presence of nanoparticles of silver in the PNG grating. The optical characterization of the gratings shows that the localized surface plasmon resonance peak shifts from 366 to 378 nm and broadens with a decrease in grating period from 10 to 2.5 μm. The surface enhanced Raman spectroscopy of the Rhodamine-6G dye coated PNG structure shows the maximum enhancement by two orders of magnitude in comparison to the randomly distributed silver nanoparticles having similar size and shape as the PNG structure

  14. The Chandra/HETG view of NGC 1365 in a Compton-thick state

    Science.gov (United States)

    Nardini, E.; Gofford, J.; Reeves, J. N.; Braito, V.; Risaliti, G.; Costa, M.

    2015-11-01

    We present the analysis of a Chandra High-Energy Transmission Grating (HETG) observation of the local Seyfert galaxy NGC 1365. The source, well known for its dramatic X-ray spectral variability, was caught in a reflection-dominated, Compton-thick state. The high spatial resolution afforded by Chandra allowed us to isolate the soft X-ray emission from the active nucleus, neglecting most of the contribution from the kpc-scale starburst ring. The HETG spectra thus revealed a wealth of He- and H-like lines from photoionized gas, whereas in larger aperture observations these are almost exclusively produced through collisional ionization in the circumnuclear environment. Once the residual thermal component is accounted for, the emission-line properties of the photoionized region close to the hard X-ray continuum source indicate that NGC 1365 has some similarities to the local population of obscured active galaxies. In spite of the limited overall data quality, several soft X-ray lines seem to have fairly broad profiles (˜800-1300 km s-1 full width at half-maximum), and a range of outflow velocities (up to ˜1600 km s-1, but possibly reaching a few thousand km s-1) appears to be involved. At higher energies, the Kα fluorescence line from neutral iron is resolved with >99 per cent confidence, and its width of ˜3000 km s-1 points to an origin from the same broad-line region clouds responsible for eclipsing the X-ray source and likely shielding the narrow-line region.

  15. The Chandra HelpDesk

    Science.gov (United States)

    Galle, Elizabeth C.

    2008-03-01

    The Chandra X-ray Center (CXC) HelpDesk has answered hundreds of user questions over the course of the Chandra mission, ranging from basic syntax errors to advanced analysis questions. This talk gives an introduction to the HelpDesk system and staff, presents a sample of recent HelpDesk requests, and discusses how user-submitted questions improve the software and documentation.

  16. X-ray emission line spectroscopy of cataclysmic variables. II. Temperatures and densities from line ratios in the Chandra HETG band

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, E. M.; Shipley, H. V. [Department of Physics and Astronomy, University of Texas-San Antonio, San Antonio, TX 78249 (United States); Rana, V. R. [Space Radiation Laboratory, Caltech, Pasadena, CA 91125 (United States); Barrett, P. E. [US Naval Observatory, Washington, DC 20392-5420 (United States); Singh, K. P., E-mail: eric.schlegel@utsa.edu, E-mail: vrana@srl.caltech.edu, E-mail: barrett.paul@usno.navy.mil, E-mail: singh@tifr.res.in [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai (India)

    2014-12-10

    We summarize the results of a line-by-line fitting analysis of the available spectra obtained using the Chandra High-Energy Transmission Grating. We confirm the existence of broad ionization and electron temperature ranges and high number densities in cataclysmic variables (CVs) of all subtypes. Temperatures range from ∼0.4 keV to ∼5-10 keV or more with a broad range detected in any given CV. In other words, single-temperature models do not describe the line emission. Number densities also cover a broad range, from 10{sup 12} to >10{sup 16} cm{sup –3}. We demonstrate that much of the plasma is in a nonequilibrium state; the Fe emission, however, may arise from plasma in the ionization equilibrium.

  17. X-ray emission line spectroscopy of cataclysmic variables. II. Temperatures and densities from line ratios in the Chandra HETG band

    International Nuclear Information System (INIS)

    We summarize the results of a line-by-line fitting analysis of the available spectra obtained using the Chandra High-Energy Transmission Grating. We confirm the existence of broad ionization and electron temperature ranges and high number densities in cataclysmic variables (CVs) of all subtypes. Temperatures range from ∼0.4 keV to ∼5-10 keV or more with a broad range detected in any given CV. In other words, single-temperature models do not describe the line emission. Number densities also cover a broad range, from 1012 to >1016 cm–3. We demonstrate that much of the plasma is in a nonequilibrium state; the Fe emission, however, may arise from plasma in the ionization equilibrium.

  18. Predicting Chandra CCD Degradation with the Chandra Radiation Model

    Science.gov (United States)

    Minow, Joseph I.; Blackwell, William C.; DePasquale, Joseph M.; Grant, Catherine E.; O'Dell, Stephen L.; Plucinsky, Paul P.; Schwartz, Daniel A.; Spitzbart, Bradley D.; Wolk, Scott J.

    2008-01-01

    Not long after launch of the Chandra X-Ray Observatory, it was discovered that the Advanced CCD Imaging Spectrometer (ACIS) detector was rapidly degrading due to radiation. Analysis by Chandra personnel showed that this degradation was due to 10w energy protons (100 - 200 keV) that scattered down the optical path onto the focal plane. In response to this unexpected problem, the Chandra Team developed a radiation-protection program that has been used to manage the radiation damage to the CCDs. This program consists of multiple approaches - scheduled sating of the ACIS detector from the radiation environment during passage through radiation belts, real-time monitoring of space weather conditions, on-board monitoring of radiation environment levels, and the creation of a radiation environment model for use in computing proton flux and fluence at energies that damage the ACIS detector. This radiation mitigation program has been very successful. The initial precipitous increase in the CCDs' charge transfer inefficiency (CTI) resulting from proton damage has been slowed dramatically, with the front-illuminated CCDS having an increase in CTI of only 2.3% per year, allowing the ASIS detector's expected lifetime to exceed requirements. This paper concentrates on one aspect of the Chandra radiation mitigation program, the creation of the Chandra Radiation Model (CRM). Because of Chandra's highly elliptical orbit, the spacecraft spends most of its time outside of the trapped radiation belts that present the severest risks to the ACIS detector. However, there is still a proton flux environment that must be accounted for in all parts of Chandra's orbit. At the time of Chandra's launch there was no engineering model of the radiation environment that could be used in the outer regions of the spacecraft's orbit, so the CRM was developed to provide the flux environment of 100 - 200 keV protons in the outer magnetosphere, magnetosheath, and solar wind regions of geospace. This

  19. 1000线/毫米软X射线自支撑闪耀透射光栅的设计与制作%Design and fabrication of 1000 line/mm soft X-ray freestanding blazed transmission gratings

    Institute of Scientific and Technical Information of China (English)

    陈勇; 邱克强; 徐向东; 刘正坤; 刘颖; 付绍军

    2012-01-01

    The performance prediction of freestanding blazed transmission grating is discussed using scalar diffraction theory, and grating design parameters are accodingly given. A freestanding transmission grating with a period of 1 lxm, duty cycle of 0.1-0.2, aspect ratio of about 100, thickness of 10 μm and fractional area of 65% is successfully fabricated by holographic lithography and anisotropic wet etching. The size of a single die is 15 mmx 15 mm divided into four 5 mmx 5 mm windows. The diffraction efficiency of the fabricated grating is tested at the National Synchrotron Radiation Laboratory in a wavelength region of 5-50 nm. The wavelength scanning results show a strong blazing effect in the direction of specular reflection from mirror-like grating sidewalls, as expected. The measured and normalized diffraction efficiency is consistent with the theoretical prediction within 38%-49% due to grating structural imperfections. These experimental results prove not only the concept of blazed transmission grating but also practicability of the fabrication process.%基于标量衍射理论讨论了软x射线自支撑闪耀透射光栅的特性并设计了光栅的结构参数.采用全息光刻和湿法腐蚀技术,成功制作了周期1μm、占空比0.1—0.2、高宽比约100、栅线厚度10μm、有效面积比为65%的自支撑闪耀透射光栅.单元尺寸为15minx15mm的硅绝缘体上含有四个5mmX5mm的自支撑闪耀透射光栅窗口.在国家同步辐射实验室检测了该光栅在5—50nm波长范围内的衍射效率.波长扫描测量结果表明,闪耀效应明显地发生在类似镜面的光栅侧壁镜面反射方向上,闪耀级次位置及其特征与标量理论预测的一致.衍射效率的实测结果基本与理论模拟符合,只是因光栅结构上的缺陷致使衍射效率偏低,峰值只有理论值的38%-49%.实验结果证明了闪耀透射光栅的概念和湿法制作工艺的可行性.

  20. CHANDRA-LETGS X-ray observations of Capella Temperature, density and abundance diagnostics

    CERN Document Server

    Ness, J U; Schmitt, J H M M; Raassen, A J J; Porquet, D; Kaastra, J S; Van der Meer, R L J; Burwitz, V; Predehl, P

    2001-01-01

    Electron density diagnostics based on the triplets of Helium-like CV, NVI, and OVII are applied to the X-ray spectra of Capella and Procyon measured with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory. New theoretical models for the calculation of the line ratios between the forbidden (f), intercombination (i), and the resonance (r) lines of the helium-like triplets are used. The derived densities are quite typical of densities found in the solar active regions, and also pressures and temperatures in Procyon's and Capella's corona at a level of T=10^6K are quite similar. We find no evidence for densities as high as measured in solar flares. Comparison of our Capella and Procyon measurements with the Sun shows little difference in the physical properties of the layers producing the CV, NVI, and OVII emission. Assuming the X-ray emitting plasma to be confined in magnetic loops, we obtain typical loop length scales of L_Capella > 8 L_Procyon from the loop scaling ...

  1. X-Ray Spectroscopy of diffuse Galactic Interstellar Matter with Chandra

    Science.gov (United States)

    Schulz, Norbert S.; Paerels, Frits

    One of the expectations with the advent of the High Energy Transmission Grating (HETG) spectrometer onboard the Chandra X-ray Observatory was to measure precise photoelectric edges of major cosmic elements such as O, Ne, Mg, Si, S, Ar, Ca, and Fe. Early studies revealed complex absorption structures around the O K, Fe L, and Ne K edges which were identified with absorption from the various phases of the interstellar medium and which could place limits on ionization fractions in these phases. The dust content in interstellar matter as well as, for example, the fraction of how much oxygen is locked into dust are issues of importance and here resolved X-ray edges can determine significant limits. I will review predictions made by cross-sections and depletion factors and compare with current observations specifically with respect to silicon absorption in the interstellar medium. Dust grain models and in conjunction with laboratory measurements are now used to improve current interstellar X-ray absorption models.

  2. The High Resolution X-ray Spectrum of SS 433 using the Chandra HETGS

    CERN Document Server

    Marshall, H L; Schulz, N S; Marshall, Herman L.; Canizares, Claude R.; Schulz, Norbert S.

    2001-01-01

    We present observations of SS 433 using the Chandra High Energy Transmission Grating Spectrometer. Many emission lines of highly ionized elements are detected with the relativistic blue and red Doppler shifts. The lines are measurably broadened to 1700 km/s (FWHM) and the widths do not depend significantly on the characteristic emission temperature, suggesting that the emission occurs in a freely expanding region of constant collimation with opening angle of 1.23 +/- 0.06 deg. The blue shifts of lines from low temperature gas are the same as those of high temperature gas within our uncertainties, again indicating that the hottest gas we observe to emit emission lines is already at terminal velocity. Fits to the emission line fluxes give a range of temperatures in the jet from 5e6 to 1e8 K. We derive the emission measure as a function of temperature for a four component model that fits the line flux data. Using the density sensitive Si XIII triplet, the characteristic electron density is 1e14 cm^{-3}, where th...

  3. The X-ray Spectrum of the Rapid Burster using the Chandra HETGS

    CERN Document Server

    Marshall, H L; Fox, D; Miller, J M; Guerriero, R; Morgan, E; Van der Klis, M; Bildsten, L; Dotani, T; Lewin, W H G

    2001-01-01

    We present observations of the Rapid Burster (RB, also known as MXB 1730-335) using the Chandra High Energy Transmission Grating Spectrometer. The average interval between type II (accretion) bursts was about 40 s. There was one type I (thermonuclear flash) burst and about 20 "mini-bursts" which are probably type II bursts whose peak flux is 10-40% of the average peak flux of the other type II bursts. The time averaged spectra of the type II bursts are well fit by a blackbody with a temperature of kT = 1.6 keV, a radius of 8.9 km for a distance of 8.6 kpc, and an interstellar column density of 1.7e22 per sq. cm. No narrow emission or absorption lines were clearly detected. The 3 sigma upper limits to the equivalent widths of any features are < 10 eV in the 1.1-7.0 keV band and as small as 1.5 eV near 1.7 keV. We suggest that Comptonization destroys absorption features such as the resonance line of Fe XXVI.

  4. The Soft X-ray Spectrum from NGC 1068 Observed with LETGS on Chandra

    CERN Document Server

    Brinkman, A C; Van der Meer, R L J; Kinkhabwala, A; Behar, E; Kahn, S M; Paerels, F B S; Sako, M

    2002-01-01

    Using the combined spectral and spatial resolving power of the Low Energy Transmission Grating (LETGS) on board Chandra, we obtain separate spectra from the bright central source of NGC 1068 (Primary region), and from a fainter bright spot 4" to the NE (Secondary region). Both spectra are dominated by line emission from H- and He-like ions of C through S, and from Fe L-shell ions, but also include narrow radiative recombination continua, indicating that most of the soft X-ray emission arises in low-temperature (kT few eV) photoionized plasma. We confirm the conclusions of Kinkhabwala et al. (2002), based on XMM-Newton RGS observations, that the entire nuclear spectrum can be explained by recombination/radiative cascade following photoionization, and radiative decay following photoexcitation, with no evidence for hot, collisionally ionized plasma. In addition, this model also provides an excellent fit to the spectrum of the Secondary region, albeit with radial column densities a factor of three lower, as would...

  5. High-Resolution X-Ray Spectroscopy of the Seyfert 2 Galaxy Circinus with Chandra

    Science.gov (United States)

    Sambruna, Rita M.; Netzer, Hagai; Kaspi, Shai; Brandt, W. N.; Chartas, G.; Garmire, G. P.; Nousek, John A.; Weaver, K. A.

    2000-01-01

    Results from a 60 ks Chandra High Energy Transmission Grating Spectrometer (HETGS) observation of the nearby Seyfert 2 Circinus are presented. The spectrum shows a wealth of emission lines at both soft and hard X-rays, including lines of Ne, Mg, Si, S, Ar, Ca, and Fe, and a prominent Fe K(alpha) line at 6.4 keV. We identify several of the He-like components and measure several of the Lyman lines of the N-like ions. The lines' profiles are unresolved at the limited signal-to-noise ratio of the data. Our analysis of the zeroth-order image in a companion paper constrains the size of the emission region to be 20-60 pc, suggesting that emission within this volume is almost entirely due to the reprocessing of the obscured central source. Here we show that a model containing two distinct components can reproduce almost all the observed properties of this gas. The ionized component can explain the observed intensities of the ionized species, assuming twice-solar composition and an N is proportional r(exp -1.5) density distribution. The neutral component is highly concentrated, well within the 0.8" point source, and is responsible for almost all of the observed K(alpha) (6.4 keV) emission. Circinus seems to be different than Mkn 3 in terms of its gas distribution.

  6. Chandra LETGS observation of the variable NLS1 galaxy Ark 564

    Science.gov (United States)

    Ramírez, J. M.

    2013-03-01

    We present an analysis of the 100 ks X-ray spectrum of the narrow-line Seyfert 1 Galaxy Ark 564, taken with the Low Energy Transmission Grating Spectrometer (LETGS) on board Chandra. Using χ2 statistics, several continuum models of the time-averaged spectrum of this object are compared, obtaining a semi-empirical solution for the description of the intrinsic emission continuum and a physical solution for the intrinsic absorption of the system. We find that the 0.1-10 keV spectrum can be well described by a power law plus two thermal components that account for the soft step. We are also able to detect and measure several narrow, unresolved absorption lines arising from highly ionized species of C, N, O, and Fe. The material seems to have a velocity consistent with the systemic velocity of the galaxy. This piece of evidence, in addition to the very low observed column density of NH ~ 1020 cm-2, is in good agreement with the scenario of a transverse biconical outflow with a gas density of n ≲ 3 × 1012 cm-3 at distances beyond the broad-line region r ≳ 10 lt-days, but a dust torus origin cannot be ruled out. The reduced spectrum is only available in electronic form at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr(130.79.128.5) or via cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A95

  7. A Chandra/HETGS Census of X-ray Variability From Sgr A* During 2012

    CERN Document Server

    Neilsen, J; Gammie, C; Dexter, J; Markoff, S; Haggard, D; Nayakshin, S; Wang, Q D; Grosso, N; Porquet, D; Tomsick, J A; Degenaar, N; Fragile, P C; Wijnands, R; Miller, J M; Baganoff, F K

    2013-01-01

    We present the first systematic analysis of the X-ray variability of Sgr A* during the Chandra X-ray Observatory's 2012 Sgr A* X-ray Visionary Project (XVP). With 38 High Energy Transmission Grating Spectrometer (HETGS) observations spaced an average of 7 days apart, this unprecedented campaign enables detailed study of the X-ray emission from this supermassive black hole at high spatial, spectral and timing resolution. In 3 Ms of observations, we detect 39 X-ray flares from Sgr A*, lasting from a few hundred seconds to approximately 8 ks, and ranging in 2-10 keV luminosity from ~1e34 erg/s to 2e35 erg/s. Despite tentative evidence for a gap in the distribution of flare peak count rates, there is no evidence for X-ray color differences between faint and bright flares. Our preliminary X-ray flare luminosity distribution dN/dL is consistent with a power law with index -1.9 (+0.3 -0.4); this is similar to some estimates of Sgr A*'s NIR flux distribution. The observed flares contribute one-third of the total X-ra...

  8. Diffractive centrosymmetric 3D-transmission phase gratings positioned at the image plane of optical systems transform lightlike 4D-WORLD as tunable resonators into spectral metrics...

    Science.gov (United States)

    Lauinger, Norbert

    1999-08-01

    Diffractive 3D phase gratings of spherical scatterers dense in hexagonal packing geometry represent adaptively tunable 4D-spatiotemporal filters with trichromatic resonance in visible spectrum. They are described in the (lambda) - chromatic and the reciprocal (nu) -aspects by reciprocal geometric translations of the lightlike Pythagoras theorem, and by the direction cosine for double cones. The most elementary resonance condition in the lightlike Pythagoras theorem is given by the transformation of the grating constants gx, gy, gz of the hexagonal 3D grating to (lambda) h1h2h3 equals (lambda) 111 with cos (alpha) equals 0.5. Through normalization of the chromaticity in the von Laue-interferences to (lambda) 111, the (nu) (lambda) equals (lambda) h1h2h3/(lambda) 111-factor of phase velocity becomes the crucial resonance factor, the 'regulating device' of the spatiotemporal interaction between 3D grating and light, space and time. In the reciprocal space equal/unequal weights and times in spectral metrics result at positions of interference maxima defined by hyperbolas and circles. A database becomes built up by optical interference for trichromatic image preprocessing, motion detection in vector space, multiple range data analysis, patchwide multiple correlations in the spatial frequency spectrum, etc.

  9. Supersymmetric Bragg gratings

    CERN Document Server

    Longhi, Stefano

    2015-01-01

    The supersymmetric (SUSY) structure of coupled-mode equations that describe scattering of optical waves in one-dimensional Bragg gratings is highlighted. This property can find applications to the synthesis of special Bragg filters and distributed-feedback (DFB) optical cavities. In particular, multiple SUSY (Darboux-Crum) transformations can be used to synthesize DFB filters with any desired number of resonances at target frequencies. As an example, we describe the design of a DFB structure with a set of equally-spaced resonances, i.e. a frequency comb transmission filter.

  10. Supersymmetric Bragg gratings

    International Nuclear Information System (INIS)

    The supersymmetric (SUSY) structure of coupled-mode equations that describe scattering of optical waves in one-dimensional Bragg gratings is highlighted. This property can find applications to the synthesis of special Bragg filters and distributed-feedback (DFB) optical cavities. In particular, multiple SUSY (Darboux–Crum) transformations can be used to synthesize DFB filters with any desired number of resonances at target frequencies. As an example, we describe the design of a DFB structure with a set of equally-spaced resonances, i.e. a frequency comb transmission filter. (paper)

  11. A New Method for Filter Design Based on Long-Period Fibre Grating

    Institute of Scientific and Technical Information of China (English)

    CHEN Kai; SHENG Qiu-Qin; DONG Xiao-Yi

    2004-01-01

    @@ We present a simple method to induce mechanically a long-period fibre grating in a general sing mode fibre. The transmission spectrum of the new type of grating can be tailored by changing the external applied pressure or by introducing a phase-shift in the grating. The tunability this kind of gratings exhibit will be particularly useful for the filter design.

  12. The Chandra Galactic Bulge Survey

    NARCIS (Netherlands)

    Hynes, Robert I.; Jonker, P.G.; Bassa, C. G.; Dieball, A.; Greiss, S.; Maccarone, T. J.; Nelemans, G.; Steeghs, D.; Torres, M. A. P.; Britt, C. T.; Clem, J. L.; Gossen, L.; Grindlay, J. E.; Groot, P.J.; Kuiper, L.; Kuulkers, E.; Mendez, M.; Mikles, V. J.; Ratti, E. M.; Rea, N.; van Haaften, L.; Wijnands, R.; in't Zand, J. J. M.

    2011-01-01

    The Chandra Galactic Bulge Survey (CGBS) is a shallow but wide survey of two approximately 6x1 degree strips of the Galactic Bulge about a degree above and below the plane. The survey by design targets regions where extinction and crowding are manageable and optical counterparts are accessible to de

  13. The Chandra Galactic Bulge Survey

    NARCIS (Netherlands)

    Hynes, Robert I.; Jonker, P. G.; Bassa, C. G.; Nelemans, G.; Steeghs, D.; Torres, M. A. P.; Maccarone, T. J.; Greiss, S.; Clem, J.; Dieball, A.; Mikles, V. J.; Britt, C. T.; Gossen, L.; Collazzi, A. C.; Wijnands, R.; In't Zand, J. J. M.; Mendez, M.; Rea, N.; Kuulkers, E.; Ratti, E. M.; van Haaften, L. M.; Heinke, C.; Ozel, F.; Groot, P. J.; Verbunt, F.

    2012-01-01

    The Chandra Galactic Bulge Survey (GBS) is a shallow but wide survey of two approximately 6x1 degree strips of the Galactic Bulge about a degree above and below the plane. The survey by design targets regions where extinction and crowding are manageable and optical counterparts are accessible to det

  14. Theoretical analysis on x-ray cylindrical grating interferometer

    CERN Document Server

    Cong, Wenxiang; Wang, Ge

    2015-01-01

    Grating interferometer is a state of art x-ray imaging approach, which can simultaneously acquire information of x-ray attenuation, phase shift, and small angle scattering. This approach is very sensitive to micro-structural variation and offers superior contrast resolution for biological soft tissues. The present grating interferometer often uses flat gratings, with serious limitations in the field of view and the flux of photons. The use of curved gratings allows perpendicular incidence of x-rays on the gratings, and gives higher visibility over a larger field of view than a conventional interferometer with flat gratings. In the study, we present a rigorous theoretical analysis of the self-imaging of curved transmission gratings based on Rayleigh-Sommerfeld diffraction. Numerical simulations have demonstrated the self-imaging phenomenon of cylindrical grating interferometer. The theoretical results are in agreement with the results of numerical simulations.

  15. High-Resolution X-ray and Ultraviolet Spectroscopy of the Complex Intrinsic Absorption in NGC 4051 with Chandra and HST

    CERN Document Server

    Collinge, M J; Kaspi, S; Crenshaw, D M; Elvis, M; Krämer, S B; Reynolds, C S; Sambruna, R M; Wills, B J; Kaspi, Shai; Elvis, Martin; Kraemer, Steven B.; Reynolds, Christopher S; Sambruna, Rita M.; Wills, Beverley J.

    2001-01-01

    We present the results from simultaneous observations of the Narrow-Line Seyfert 1 galaxy NGC 4051 with the Chandra High Energy Transmission Grating Spectrometer and the HST Space Telescope Imaging Spectrograph. The X-ray grating spectrum reveals absorption and emission lines from hydrogen-like and helium-like ions of O, Ne, Mg and Si. We resolve two distinct X-ray absorption systems: a high-velocity blueshifted system at -2340+/-130 km/s and a low-velocity blueshifted system at -600+/-130 km/s. In the UV spectrum we detect strong absorption, mainly from C IV, N V and Si IV, that is resolved into as many as nine different intrinsic absorption systems with velocities between -650 km/s and 30 km/s. Although the low-velocity X-ray absorption is consistent in velocity with many of the UV absorption systems, the high-velocity X-ray absorption seems to have no UV counterpart. In addition to the absorption and emission lines, we also observe rapid X-ray variability and a state of low X-ray flux during the last ~15 k...

  16. 大面积软X射线自支撑金透射光栅的研制%Fabrication of large area self-supported gold transmission grating for soft X-ray

    Institute of Scientific and Technical Information of China (English)

    邱克强; 刘正坤; 陈火耀; 徐向东; 刘颖; 洪义麟; 付绍军

    2011-01-01

    To meet the need of soft X-ray self-supported transmission gratings for space detecting and plasma diagnostics, self-supported gold transmission gratings were successfully fabricated with the holographic lithography and plating technology. To obtain photo-resist mask patterns with steep side-walls, a layer of Anti-reflection Coating (ARC) was used to attenuate standing wave resulting from the substrate with high reflectivity. Then,a plating mask was obtained by coating a protective chrome on the mask and using Reactive Ion Etching (RIE). In this process, the plating mask with desired duty cycle could be fabricated via changing the thickness of the protective coating. Finally, a self-supported transmission grating with a line density of 3 450 gr/mm (290 nm period), a duty cycle of 0. 55 and 400 nm thick gold bars was fabricated by plating gold in grooves of plating mask. The grating size is up to 10 mm× 15 mm, and its +1 order diffraction efficiency is about 5% in the soft X-ray band be-tween 5 and 12 nm in the National Synchrotron Radiation Laboratory (NSRL).%针对等离子体诊断及空间环境探测等领域对软X射线透射光栅的需要,采用全息光刻和微电镀技术制作了自支撑软X射线金透射光栅.在基底与光刻胶之间增加减反膜层以降低高反射基底引起的驻波效应对掩模槽形的影响,使用全息光刻技术获得了侧壁陡直的光栅掩模.然后,在掩模顶部镀保护层并使用反应离子刻蚀获得电镀掩模,通过改变保护层厚度来调节电镀掩模的占宽比.最后,利用微电镀技术沉积金,成功制作了线条密度为3 450 gr/mm的自支撑透射光栅,光栅周期约为290 nm,占宽比为0.55,金吸收体为500 nm,光栅尺寸达到10 mm× 15 mm.在国家同步辐射装置上,测得在5~12 nm软X射线波段其+1级透射衍射效率约为5%.

  17. Chandra Independently Determines Hubble Constant

    Science.gov (United States)

    2006-08-01

    A critically important number that specifies the expansion rate of the Universe, the so-called Hubble constant, has been independently determined using NASA's Chandra X-ray Observatory. This new value matches recent measurements using other methods and extends their validity to greater distances, thus allowing astronomers to probe earlier epochs in the evolution of the Universe. "The reason this result is so significant is that we need the Hubble constant to tell us the size of the Universe, its age, and how much matter it contains," said Max Bonamente from the University of Alabama in Huntsville and NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala., lead author on the paper describing the results. "Astronomers absolutely need to trust this number because we use it for countless calculations." Illustration of Sunyaev-Zeldovich Effect Illustration of Sunyaev-Zeldovich Effect The Hubble constant is calculated by measuring the speed at which objects are moving away from us and dividing by their distance. Most of the previous attempts to determine the Hubble constant have involved using a multi-step, or distance ladder, approach in which the distance to nearby galaxies is used as the basis for determining greater distances. The most common approach has been to use a well-studied type of pulsating star known as a Cepheid variable, in conjunction with more distant supernovae to trace distances across the Universe. Scientists using this method and observations from the Hubble Space Telescope were able to measure the Hubble constant to within 10%. However, only independent checks would give them the confidence they desired, considering that much of our understanding of the Universe hangs in the balance. Chandra X-ray Image of MACS J1149.5+223 Chandra X-ray Image of MACS J1149.5+223 By combining X-ray data from Chandra with radio observations of galaxy clusters, the team determined the distances to 38 galaxy clusters ranging from 1.4 billion to 9.3 billion

  18. Chandra Catches "Piranha" Black Holes

    Science.gov (United States)

    2007-07-01

    Supermassive black holes have been discovered to grow more rapidly in young galaxy clusters, according to new results from NASA's Chandra X-ray Observatory. These "fast-track" supermassive black holes can have a big influence on the galaxies and clusters that they live in. Using Chandra, scientists surveyed a sample of clusters and counted the fraction of galaxies with rapidly growing supermassive black holes, known as active galactic nuclei (or AGN). The data show, for the first time, that younger, more distant galaxy clusters contained far more AGN than older, nearby ones. Galaxy clusters are some of the largest structures in the Universe, consisting of many individual galaxies, a few of which contain AGN. Earlier in the history of the universe, these galaxies contained a lot more gas for star formation and black hole growth than galaxies in clusters do today. This fuel allows the young cluster black holes to grow much more rapidly than their counterparts in nearby clusters. Illustration of Active Galactic Nucleus Illustration of Active Galactic Nucleus "The black holes in these early clusters are like piranha in a very well-fed aquarium," said Jason Eastman of Ohio State University (OSU) and first author of this study. "It's not that they beat out each other for food, rather there was so much that all of the piranha were able to really thrive and grow quickly." The team used Chandra to determine the fraction of AGN in four different galaxy clusters at large distances, when the Universe was about 58% of its current age. Then they compared this value to the fraction found in more nearby clusters, those about 82% of the Universe's current age. The result was the more distant clusters contained about 20 times more AGN than the less distant sample. AGN outside clusters are also more common when the Universe is younger, but only by factors of two or three over the same age span. "It's been predicted that there would be fast-track black holes in clusters, but we never

  19. Sampled phase-shift fiber Bragg gratings

    Institute of Scientific and Technical Information of China (English)

    Xu Wang(王旭); Chongxiu Yu(余重秀); Zhihui Yu(于志辉); Qiang Wu(吴强)

    2004-01-01

    A phase-shift fiber Bragg grating (FBG) with sampling is proposed to generate a multi-channel bandpass filter in the background of multi-channel stopbands. The sampled noire fiber gratings are analyzed by Fourier transform theory first, and then simulation and experiment are performed, the results show that transmission peaks are opened in every reflective channel, the spectrum shape of every channel is identical.It can be used to fabricate multi-wavelength distributed feedback (DFB) fiber laser.

  20. A Deep Chandra X-Ray Spectrum of the Accreting Young Star TW Hydrae

    Science.gov (United States)

    Brickhouse, N. S.; Cranmer, S. R.; Dupree, A. K.; Luna, G. J. M.; Wolk, S.

    2010-02-01

    We present X-ray spectral analysis of the accreting young star TW Hydrae from a 489 ks observation using the Chandra High Energy Transmission Grating. The spectrum provides a rich set of diagnostics for electron temperature Te , electron density Ne , hydrogen column density NH , relative elemental abundances, and velocities, and reveals its source in three distinct regions of the stellar atmosphere: the stellar corona, the accretion shock, and a very large extended volume of warm postshock plasma. The presence of Mg XII, Si XIII, and Si XIV emission lines in the spectrum requires coronal structures at ~10 MK. Lower temperature lines (e.g., from O VIII, Ne IX, and Mg XI) formed at 2.5 MK appear more consistent with emission from an accretion shock. He-like Ne IX line ratio diagnostics indicate that Te = 2.50 ± 0.25 MK and Ne = 3.0 ± 0.2 × 1012 cm-3 in the shock. These values agree well with standard magnetic accretion models. However, the Chandra observations significantly diverge from current model predictions for the postshock plasma. This gas is expected to cool radiatively, producing O VII as it flows into an increasingly dense stellar atmosphere. Surprisingly, O VII indicates Ne = 5.7+4.4 -1.2 × 1011 cm-3, 5 times lower than Ne in the accretion shock itself and ~7 times lower than the model prediction. We estimate that the postshock region producing O VII has roughly 300 times larger volume and 30 times more emitting mass than the shock itself. Apparently, the shocked plasma heats the surrounding stellar atmosphere to soft X-ray emitting temperatures and supplies this material to nearby large magnetic structures—which may be closed magnetic loops or open magnetic field leading to mass outflow. Our model explains the soft X-ray excess found in many accreting systems as well as the failure to observe high Ne signatures in some stars. Such accretion-fed coronae may be ubiquitous in the atmospheres of accreting young stars.

  1. Chandra Discovers the X-ray Signature of a Powerful Wind from a Galactic Microquasar

    Science.gov (United States)

    2000-11-01

    profiles have been observed for over one hundred years. "When you see a P Cygni profile, you immediately know the object you are observing is producing a powerful outflow," Brandt says. Chandra is the first X-ray observatory capable of capturing data of sufficiently high resolution to reveal an X-ray P Cygni profile. Brandt and Schulz say their discovery occurred because they were able to use Chandra continuously for one-third of a day to observe Circinus X-1, plus its signal in X rays is generally very bright, partly because it is relatively nearby in our own Galaxy. P Cygni lines at ultraviolet or optical wavelengths had not been previously seen from Circinus X-1 because a large amount of dust in the galactic plane lies between Earth and this system and this dust is an efficient absorber of ultraviolet and optical light. However, the energetic X rays created by Circinus X-1 could easily penetrate through the obscuring dust and gas--similar to the way medical X-rays on Earth can penetrate through people's bodies. "We were hoping to detect some kind of X-ray line emission from the accreting neutron star in Circinus X-1, but it caught us totally by surprise to observe a complex emission structure like a P Cygni profile in high-energy X rays." schulz says. "This detection clearly marks a new area in X-ray astrophysics, where we will be able to study dynamical structures in the universe like we currently do at ultraviolet or optical wavelengths." Brandt and Schulz used two of Chandra's instruments, known together as the High-Energy Transmission Grating Spectrometer (HETGS), to detect the X rays and produce a high-resolution X-ray spectrum of Circinus X-1. This spectrum is analogous to the rainbow we can see at optical wavelengths. "Chandra's X-ray spectrum is 50 times more detailed than previous X-ray observatories could obtain," Schulz says. First, the super-fine transmission gratings acted like a prism to separate the X-rays into discrete energy bands. Then, the Advanced

  2. A Census of X-ray gas in NGC 1068: Results from 450ks of Chandra HETG Observations

    Science.gov (United States)

    Kallman, T.; Evans, Daniel A.; Marshall, H.; Canizares, C.; Longinotti, A.; Nowak, M.; Schulz, N.

    2016-01-01

    We present models for the X-ray spectrum of the Seyfert 2 galaxy NGC 1068. These are fitted to data obtained using the High Energy Transmission Grating (HETG) on the Chandra X-ray observatory. The data show line and radiative recombination continuum (RRC) emission from a broad range of ions and elements. The models explore the importance of excitation processes for these lines including photoionization followed by recombination, radiative excitation by absorption of continuum radiation and inner shell fluorescence. The models show that the relative importance of these processes depends on the conditions in the emitting gas, and that no single emitting component can fit the entire spectrum. In particular, the relative importance of radiative excitation and photoionization/recombination differs according to the element and ion stage emitting the line. This in turn implies a diversity of values for the ionization parameter of the various components of gas responsible for the emission, ranging from log(ξ)=1 – 3. Using this, we obtain an estimate for the total amount of gas responsible for the observed emission. The mass flux through the region included in the HETG extraction region is approximately 0.3 M⊙ yr−1 assuming ordered flow at the speed characterizing the line widths. This can be compared with what is known about this object from other techniques.

  3. Chandra Detection of the First X-ray Forest along the Line of Sight To Mkn 421

    CERN Document Server

    Nicastro, F; Elvis, M; Drake, J; Fiore, F; Fang, T; Fruscione, A; Krongold, Y; Marshall, H; Williams, R; Nicastro, Fabrizio; Mathur, Smita; Elvis, Martin; Drake, Jeremy; Fiore, Fabrizio; Fang, Taotao; Fruscione, Antonella; Krongold, Yair; Marshall, Herman; Williams, Rik

    2005-01-01

    We present the first >=3.5 sigma (conservative) or >=5.8 sigma (sum of lines significance) detection of two Warm-Hot Intergalactic Medium (WHIM) filaments at z>0, which we find along the line of sight to the blazar Mkn 421. These systems are detected through highly ionized resonant metal absorption in high quality Chandra-ACIS and -HRC Low Energy Transmission Grating (LETG) spectra of Mkn 421, obtained following our two Target of Opportunity requests during two outburst phases. The two intervening WHIM systems that we detect, have OVII and NVII columns of N(OVII)=(1.0 +/- 0.3) x 1e15 cm-2} N(NVII)=(0.8 +/- 0.4) x 1e15 cm-2, and N(OVII)=(0.7 +/- 0.3) x 1e15 cm-2, N(NVII)=(1.4 +/- 0.5) x 1e15 cm-2 respectively. From the detected number of WHIM filaments along this line of sight we can estimate the number of OVII filaments per unit redshift with columns larger than 7e14 cm-2, dP(OVII)/dz(N(OVII)>=7e14) = 67^{+88}_{-43}, consistent, within the large 1-sigma errors, with the hydrodynamical simulation predictions o...

  4. Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State

    CERN Document Server

    Nowak, Michael A; Trowbridge, Sarah N; Markoff, Sera B; Wilms, Joern; Pottschmidt, Katja; Coppi, Paolo; Maitra, Dipankar; Davis, John E; Tramper, Frank

    2010-01-01

    Using Suzaku and the Rossi X-ray Timing Explorer, we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard low states. Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the focused wind from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating. These latter spectra are crucial for revealing the ionized absorption due to the secondary's focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All thre...

  5. The complex circumnuclear environment of the broad-line radio galaxy 3C 390.3 revealed by Chandra HETG

    CERN Document Server

    Tombesi, F; Kallman, T; Reynolds, C S; Mushotzky, R F; Braito, V; Behar, E; Leutenegger, M A; Cappi, M

    2016-01-01

    We present the first high spectral resolution X-ray observation of the broad-line radio galaxy 3C 390.3 obtained with the high energy transmission grating (HETG) spectrometer on board the Chandra X-ray Observatory. The spectrum shows complex emission and absorption features in both the soft X-rays and Fe K band. We detect emission and absorption lines in the energy range between E = 700-1000 eV associated with ionized Fe L transitions (Fe XVII-XX). An emission line at the energy of E=6.4 keV consistent with the Fe K\\alpha is also observed. Our best-fit model requires at least three different components: (i) a hot emission component likely associated with the hot interstellar medium in this elliptical galaxy with temperature kT=0.5+/-0.1 keV; (ii) a warm absorber with ionization parameter log\\xi=2.3+/-0.5 erg s^{-1} cm, column density logN_H=20.7+/-0.1 cm^{-2}, and outflow velocity of v_{out}<150 km s^{-1}; (iii) a lowly ionized reflection component in the Fe K band likely associated with the optical broad ...

  6. Investigation into the design and diffraction efficiency of shifted dual transmission grating%基于移位双光栅色散元件的X射线谱仪研制∗

    Institute of Scientific and Technical Information of China (English)

    易涛; 王传珂; 杨进文; 朱效立; 谢常青; 刘慎业

    2016-01-01

    In inertial confined fusion (ICF) experiments, the temporal evolution of X-ray spectrum can provide important diagnostic information such as electron temperature and density on laser-plasma interaction. Accurate diagnostic requires a wide range of X-ray spectrum from several hundred eV to kilo eV to be measured with high temporal resolution. For traditional single grating spectrometer coupled with streak cameras, the limited recording length of streak cameras severely restricts measured X-ray spectral range in one laser shot. Here we design a shifted dual transmission grating (SDTG) spectrometer for laser-produced plasma X-ray diagnostics in ICF experiments which can provide wide-range X-ray spectrum measurement from 100 eV to 5 keV with high temporal and spectral resolution. This SDTG spectrometer comprises two X-ray gratings: one with high line density and the other with low line density. The high line density grating is used to measure X-ray spectrum from 1000 eV to 5000 eV and the low line density grating measures X-ray spectrum from 100 eV to 1000 eV respectively. These two kinds of X-ray gratings are arranged in a plane with their centers shifted by a certain distance. A shifted double slit component is designed according to the spatial positions of the two gratings and set in front of the photocathode in the streak camera to ensure that two sets of X-ray spectra by two shifted gratings are projected on the photocathode without overlapping. This novel SDTG-based X-ray spectrometer can take the most of recording panel space, offering a path to realize a high resolution and broad spectral ranges in diagnosing soft X-rays. In this paper, the design method and the technical data of the SDTG-based X-ray spectrometer are given. The SDTG-based X-ray spectrometer is integrated, debugged and used to measure X-ray pulse at SG-III prototype facility located in Laser Fusion Research Center of Chinese Academy of Engineering Physics. The time integral results are captured

  7. Ultrafast transient grating radiation to optical image converter

    Science.gov (United States)

    Stewart, Richard E; Vernon, Stephen P; Steel, Paul T; Lowry, Mark E

    2014-11-04

    A high sensitivity transient grating ultrafast radiation to optical image converter is based on a fixed transmission grating adjacent to a semiconductor substrate. X-rays or optical radiation passing through the fixed transmission grating is thereby modulated and produces a small periodic variation of refractive index or transient grating in the semiconductor through carrier induced refractive index shifts. An optical or infrared probe beam tuned just below the semiconductor band gap is reflected off a high reflectivity mirror on the semiconductor so that it double passes therethrough and interacts with the radiation induced phase grating therein. A small portion of the optical beam is diffracted out of the probe beam by the radiation induced transient grating to become the converted signal that is imaged onto a detector.

  8. Chandra Observations of Neutron Stars -- An Overview

    OpenAIRE

    Weisskopf, M. C.

    2002-01-01

    We present a brief review of Chandra observations of neutron stars, with a concentration on neutron stars in supernova remnants. The early Chandra results clearly demonstrate how critical the angular resolution has been in order to separate the neutron star emission from the surrounding nebulosity.

  9. Chandra Multi-wavelength Plane Survey

    NARCIS (Netherlands)

    P. Zhao; J.E. Grindlay; J. Hong; M. Servillat; M. van den Berg

    2014-01-01

    Chandra Multi-wavelength Plane Survey (ChaMPlane) surveys the X-ray point sources discovered by the Chandra X-ray Observatory in the galactic plane in order to constrain the populations of faint (L x ≤ 1033 erg/s) accretion-powered sources in the Galaxy. This multi-wavelength survey includes data fr

  10. Contemporaneous Chandra HETG and Suzaku X-ray observations of NGC 4051

    Science.gov (United States)

    Lobban, A. P.; Reeves, J. N.; Miller, L.; Turner, T. J.; Braito, V.; Kraemer, S. B.; Crenshaw, D. M.

    2011-07-01

    We present the results of a deep 300 ks Chandra High Energy Transmission Grating (HETG) observation of the highly variable narrow-line Seyfert Type 1 galaxy NGC 4051. The HETG spectrum reveals 28 significant soft X-ray ionized lines in either emission or absorption; primarily originating from H-like and He-like K-shell transitions of O, Ne, Mg and Si (including higher order lines and strong forbidden emission lines from O VII and Ne IX) plus high-ionization L-shell transitions from Fe XVII to Fe XXII and lower ionization inner-shell lines (e.g. O VI). Modelling the data with XSTAR requires four distinct ionization zones for the gas, all outflowing with velocities log ξ= 4.1+0.2-0.1; vout˜-0.02c) which potentially may have a significant effect on the host galaxy environment via feedback. Finally, we also simultaneously model the broad-band 2008 XIS+HXD (Hard X-ray Detector) Suzaku data with archival Suzaku data from 2005 when the source was observed to have entered an extended period of low flux in an attempt to analyse the cause of the long-term spectral variability. We find that we can account for this by allowing for large variations in the normalization of the intrinsic power-law component which may be interpreted as being due to significant changes in the covering fraction of a Compton-thick partial-coverer obscuring the central continuum emission.

  11. Coordinated Optical/X-ray observations of the CTTS V2129 Oph The Chandra View

    Science.gov (United States)

    Flaccomio, E.; Argiroffi, C.; Alencar, S. H. P.; Bouvier, J.; Donati, J.-F.; Getman, K.; Gregory, S. G.; Hussain, G.; Ibrahimov, M.; Jardine, M. M.; Skelly, M.; Walter, F.

    2011-12-01

    Young low-mass accreting stars (classical T Tauri stars; CTTSs) possess strong magnetic fields that are responsible for the regulation of the accretion and outflow processes, and the confinement and heating of coronal plasma. Understanding the physics of CTTS magnetospheres and of their interaction with circumstellar disks can elucidate the history and evolution of our own Sun and Solar System, at the stage when planets were being formed. In June 2009 we have conducted an extensive multi-wavelength observing campaign of V2129 Oph, a K5 CTTS in the ρ Ophiuchi molecular cloud, with the goal of obtaining a synoptic view of its photosphere, magnetic field, coronal plasma, and of its accretion spot(s) and funnel flow(s). We here report on the X-ray emission, as observed by the Chandra High Energy Transmission Grating (HETG). High-density plasma, presumably from the accretion shock, is responsible for the soft X-ray emission, at least during the first half of the observation. The X-ray emission from both the coronal plasma (T˜20MK) and the cooler and denser material from the accretion spot (T˜3MK) is observed to vary between the first and second half of the observation. From the high-resolution X-ray spectra we constrain the emission measure of the two components and the density of the cool plasma. Finally we interpret the time variability of the cool plasma component in terms of stellar rotation and the time-changing viewing angle of the accretion stream, as constrained by simultaneous optical observations.

  12. Chandra Observations of Starburst Galaxies

    Science.gov (United States)

    Prestwich, Andrea; Lavoie, Anthony R. (Technical Monitor)

    2000-01-01

    We present early X-ray results from Chandra for two starburst galaxies, M82 and NGC3256, obtained using AXAF CCD Imaging Spectrometer (ACIS-I) and the HRC. For M82 the arcsecond spatial resolution enables us to separate the point source component from the extended emission for the first time. Astrometry reveals that most of the X-ray sources are not coincident with the family of compact radio sources believed to be Super Nova Remnants (SNRs). In addition, based on three epoch Chandra observations, several of the X-ray sources are clearly variable indicating that they are binaries. When we deconvolve the extended and point source components detected in the hard X-ray band, we find that 50 percent arises from the extended component. This fact, together with its morphology, constrains the various models proposed to explain the hard X-ray emission. For NGC3256 we resolve two closely separated nuclei. These new data support a pure starburst origin for the total X-ray emission rather than a composite AGN/starburst, thereby making NGC3256 one of the most X-ray luminous starburst galaxies known.

  13. Evolution of the Chandra CCD Spectra of SNR 1987A: Probing the Reflected-Shock Picture

    CERN Document Server

    Zhekov, Svetozar A; McCray, Richard; Racusin, Judith L; Burrows, David N

    2010-01-01

    We continue to explore the validity of the reflected shock structure (RSS) picture in SNR 1987A that was proposed in our previous analyses of the X-ray emission from this object. We used an improved version of our RSS model in a global analysis of 14 CCD spectra from the monitoring program with Chandra. In the framework of the RSS picture, we are able to match both the expansion velocity curve deduced from the analysis of the X-ray images and light curve. Using a simplified analysis, we also show that the X-rays and the non-thermal radio emission may originate from the same shock structure (the blast wave). We believe that using the RSS model in the analysis of grating data from the Chandra monitoring program of SNR 1987A that cover a long enough time interval, will allow us to build a more realistic physical picture and model of SNR 1987A.

  14. Investigations on birefringence effects in polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Hu, Xiaolian; Saez-Rodriguez, D.; Bang, Ole;

    2014-01-01

    birefringence effects in (m)POFBGs. To achieve this, highly reflective gratings were inscribed with the phase mask technique. They were then monitored in transmission with polarized light. For this, (m)POF sections a few cm in length containing the gratings were glued to angled silica fibers. Polarization...

  15. Compact Bragg Gratings for Long-Range Surface Plasmon Polaritons

    DEFF Research Database (Denmark)

    Boltasseva, Alexandra; Bozhevolnyi, Sergey I; Nikolajsen, Thomas;

    2006-01-01

    By introducing periodic thickness-modulation of thin metal stripes embedded in a dielectric, we realize compact and efficient Bragg gratings for long-range surface plasmon polaritons (LR-SPPs) operating around 1550 nm. We measure reflection and transmission spectra of the gratings having different...

  16. Wavelength-independent field enhancement in subwavelength gratings

    DEFF Research Database (Denmark)

    Ivinskaya, Aliaksandra; Novitsky, Andrey; Shyroki, D.;

    2011-01-01

    We show that lamellar metal gratings exhibit total transmission of incident radiation and strong nonresonant electric field enhancement in extremely subwavelength regime (in the nanometer-sized slits). With high accuracy the enhancement equals the ratio of the grating period to the slit width, it...... is independent on the wavelength and metal thickness....

  17. Subwavelength metal grating metamaterial for polarization selective optical antireflection coating

    CERN Document Server

    Kim, Wonkyu; Hendrickson, Joshua

    2015-01-01

    A metamaterial structure consisting of a one-dimensional metal/air-gap subwavelength grating is investigated for optical antireflection coating on germanium substrate in the infrared regime. For incident light polarized perpendicularly to the grating lines, the metamaterial exhibits effective dielectric property and Fabry-Perot like plasmon-coupled optical resonance results in complete elimination of reflection and enhancement of transmission. It is found that the subwavelength grating metamaterial antireflection structure does not require a deep subwavelength grating period, which is advantageous for device fabrication. Maximal transmittance of 93.4% with complete elimination of reflection is seen in the mid-wave infrared range.

  18. Thin film coated submicron gratings: theory, design, fabrication and application

    Energy Technology Data Exchange (ETDEWEB)

    Heine, C.

    1996-12-31

    The realization of new applications of submicron grating structures requires efficient theoretical methods and elaborate fabrication techniques. In this work rigorous diffraction theory for one-dimensional gratings has been investigated and optimization techniques, based on methods used in thin film optics, have been developed. Submicron gratings embossed in polycarbonate have been fabricated and characterized. This includes transmission measurements which are in good agreement with theoretical calculations. Designs for a wide range of optical filters, which lead to improved optical and mechanical properties, are presented. This has been demonstrated for broadband antireflection structures for solar energy applications, based on MgF{sub 2}-coated gratings. (author) figs., tabs., refs.

  19. First order Bragg grating filters in silicon on insulator waveguides

    Science.gov (United States)

    Waugh, Peter Michael

    2008-08-01

    The subject of this project is the design; analysis, fabrication and characterisation of first order Bragg Grating optical filters in Silicon-on-Insulator (SOI) planar waveguides. It is envisaged that this work will result in the possibility of Bragg Grating filters for use in Silicon Photonics. It is the purpose of the work to create as far as is possible flat surface waveguides so as to facilitate Thermo-Optic tuning and also the incorporation into rib-waveguide Silicon Photonics. The spectral response of the shallow Bragg Gratings was modelled using Coupled Mode Theory (CMT) by way of RSoft Gratingmod TM. Also the effect of having a Bragg Grating with alternate layers of refractive index of 1.5 and 3.5 was simulated in order to verify that Silica and Silicon layered Bragg Gratings could be viable. A series of Bragg Gratings were patterned on 1.5 micron SOI at Philips in Eindhoven, Holland to investigate the variation of grating parameters with a) the period of the gratings b) the mark to space ratio of the gratings and c) the length of the region converted to Bragg Gratings (i.e. the number of grating period repetitions). One set of gratings were thermally oxidised at Philips in Eindhoven and another set were ion implanted with Oxygen ions at the Ion Beam Facility, University of Surrey, England. The gratings were tested and found to give transmission minima at approximately 1540 nanometres and both methods of creating flat surfaces were found to give similar minima. Atomic Force Microscopy was applied to the grating area of the as-implanted samples in the Advanced Technology Institute, University of Surrey, which were found to have surface undulations in the order of 60 nanometres.

  20. The Chandra X-Ray Optics

    CERN Document Server

    Weisskopf, Martin C

    2011-01-01

    Significant advances in science always take place when the state of the art in instrumentation improves dramatically. NASA's Chandra X-Ray Observatory represents such an advance. Launched in July of 1999, Chandra is an observatory designed to study the x-ray emission from all categories of astronomical objects --- from comets, planets, and normal stars to quasars, galaxies, and clusters of galaxies. At the heart of this observatory is the precision X-Ray optic that has been vital for Chandra's outstanding success and which features an angular resolution improved by an order of magnitude compared to its forerunners. The Chandra mission is now entering its 13-th year of operation. Given that the Observatory was designed for a minimum of 3 years of operation testifies to its robust and carefully thought out design. We review the design and construction of the remarkable telescope, present examples of its usage for astronomy and astrophysics, and speculate upon the future.

  1. Chandra Observations of SNR RCW 103

    OpenAIRE

    Frank, Kari A.; Burrows, David N.; Park, Sangwook

    2015-01-01

    We analyze three Chandra observations, with a combined exposure time of 99 ks, of the Galactic supernova remnant RCW 103, a young supernova remnant, previously with no clear detection of metal-rich ejecta. Based on our imaging and spectral analyses of these deep Chandra data, we find evidence for metal-rich ejecta emission scattered throughout the remnant. X-ray emission from the shocked ejecta is generally weak, and the shocked circumstellar medium (CSM) is a largely dominant component acros...

  2. Solving the problem of electromagnetic wave diffraction at a finite plane grating with small elements

    Science.gov (United States)

    Kyurkchan, A. G.; Manenkov, S. A.

    2016-09-01

    Two approaches for solving the three-dimensional problem of wave diffraction at a finite grating consisting of bodies of revolution are proposed. An approximate solution is obtained for a grating with small elements. This solution is applied to consider gratings with a large number of elements. The coincidence of the results obtained by the two methods is shown. The reflection and transmission coefficients are compared for finite and infinite gratings.

  3. Flat acoustic lens by acoustic grating with curled slits

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Pai; Xiao, Bingmu; Wu, Ying, E-mail: ying.wu@kaust.edu.sa

    2014-10-03

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry–Perot resonance. - Highlights: • Expression of transmission coefficient of an acoustic grating with curled slits. • Non-dispersive and tunable effective medium parameters for the acoustic grating. • A flat acoustic focusing lens with gradient index by using the acoustic grating.

  4. History of grating images

    Science.gov (United States)

    Iwata, Fujio

    2001-06-01

    Toppan Printing Co., Ltd. originated the name of 'grating image'. It means an image that consists of diffraction grating dots that look similar to the halftone dots of conventional printing. We proposed this new display method using simple gratings in order to enhance the visual effects when illumination is made by a fluorescent lamp. We considered the use of simple gratings as elemental dots, and used a number of elemental dots to display a 2D image. This method produces an effect something like the halftone dots of printing. The grating image technology grows from its starting to become able to produce 3D images and a 3D-video system using an electron beam grating-writing system.

  5. Grating image technology

    Science.gov (United States)

    Iwata, Fujio

    1995-07-01

    The word 'grating image' was first named by Toppan Printing Company, Ltd. It means that an image consists of grating dots. In 1988, we presented this new technology at the Optical Security Systems Symposium, in Switzerland. Then it was improved and applied in display application. Recently, it was further applied in 3D video systems. In this report, the development history and the recent situations of grating image technology are described.

  6. Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system I. The non-dip spectrum in the low/hard state

    CERN Document Server

    Hanke, Manfred; Nowak, Michael A; Pottschmidt, Katja; Schulz, Norbert S; Lee, Julia C

    2008-01-01

    We present analyses of a 50 ks observation of the supergiant X-ray binary system Cygnus X-1/HDE 226868 taken with the Chandra High Energy Transmission Grating Spectrometer (HETGS). Cyg X-1 was in its spectrally hard state and the observation was performed during superior conjunction of the black hole, allowing for the spectroscopic analysis of the accreted stellar wind along the line of sight. A significant part of the observation covers X-ray dips as commonly observed for Cyg X-1 at this orbital phase, however, here we only analyze the high count rate non-dip spectrum. The full 0.5-10 keV continuum can be described by a single model consisting of a disk, a narrow and a relativistically broadened Fe Kalpha line, and a power law component, which is consistent with simultaneous RXTE broad band data. We detect absorption edges from overabundant neutral O, Ne and Fe, and absorption line series from highly ionized ions and infer column densities and Doppler shifts. With emission lines of He-like Mg XI, we detect t...

  7. High-Energy Processes in Young Stars: Chandra X-ray Spectroscopy of HDE 283572, RY Tau, and LkCa 21

    CERN Document Server

    Audard, M; Smith, K W; Güdel, M; Pallavicini, R; Audard, Marc; Skinner, Stephen L.; Smith, Kester W.; Guedel, Manuel; Pallavicini, Roberto

    2004-01-01

    Weak-lined T Tauri stars (WTTS) represent the important stage of stellar evolution between the accretion phase and the zero-age main sequence. At this stage, the star decouples from its accretion disk, and spins up to a higher rotation rate than in the preceding classical T Tauri phase. Consequently, dynamo processes can be expected to become even stronger at this stage. High energy processes can have effects on the remaining circumstellar material, possibly including protoplanets and planetesimals, and these effects may account for certain observable properties of asteroids in the current solar system. Chandra observed for 100 ks the WTTS HDE 283572 which probes the PMS stage of massive A-type stars. We present first results of the analysis of its high-resolution X-ray spectrum obtained with the High-Energy Transmission Grating Spectrometer. A wide range of Fe lines of high ionization states are observed, indicating a continuous emission measure distribution. No significant signal is detected longward of the...

  8. Fiber Bragg grating sensors

    NARCIS (Netherlands)

    Cheng, L.K.; Nieuwland, R.A.; Toet, P.M.; Agovic, K.

    2010-01-01

    A brief overview of fiber Bragg grating based sensor technology from sensor head, read out unit and commercial applications is given. Fiber Bragg grating based sensor systems are becoming mature rapidly. Components for commercial pressure sensors and temperature sensors are available and slowly gett

  9. Bragg gratings in Topas

    DEFF Research Database (Denmark)

    Zhang, C.; Webb, D.J.; Kalli, K.;

    We report for the first time fibre Bragg grating inscription in microstructured optical fibre fabricated from Topas® cyclic olefin copolymer. The temperature sensitivity of the grating was studied revealing a positive Bragg wavelength shift of approximately 0.8 nmK-1,the largest sensitivity yet...

  10. Bidirectional grating compressors

    Science.gov (United States)

    Wang, Cheng; Li, Zhaoyang; Li, Shuai; Liu, Yanqi; Leng, Yuxin; Li, Ruxin

    2016-07-01

    A bidirectional grating compressor for chirped pulse amplifiers is presented. It compresses a laser beam simultaneously in two opposite directions. The pulse compressor is shown to promote chirped pulse amplifiers' output energy without grating damages. To verify the practicability, an experiment is carried out. In addition, a crosscorrelation instrument is designed and set up to test the time synchronization between these two femtosecond pulses.

  11. Fractal Diffraction Grating

    OpenAIRE

    Bak, Dongsu; Kim, Sang Pyo; Kim, Sung Ku; Soh, Kwang-Sup; Yee, Jae Hyung

    1998-01-01

    We consider an optical diffraction grating in which the spatial distribution of open slits forms a fractal set. The Fraunhofer diffraction patterns through the fractal grating are obtained analytically for the simplest triad Cantor type and its generalized version. The resulting interference patterns exhibit characteristics of the original fractals and their scaling properties.

  12. Effect of Effective Refractive Index of Grating in FBG Splitter

    Directory of Open Access Journals (Sweden)

    DINESH ARORA

    2011-09-01

    Full Text Available The Fiber Bragg Gratings have been used extensively in the communication industry. Fiber Bragg grating is written directly into the core of the optical fiber and it is quite an attractive technique for wavelength splitter since it provides high reflectivity at a certain wavelength, with negligible transmission losses for others, providing a wavelength-channel selection with low crosstalk between adjacent channels.In this paper we propose a Fiber Bragg Grating base splitter with alteration of effective refractive index of grating for Ethernet passive optical network. With the increase in the effective refractive index the reflectivity of grating is increased. We analysed the effect of effective refractive index on reflectivity of grating. In our work the Bragg wavelength has been fixed at 1550 nm,length of the grating as 10mm and with effective refractive index as 4.0 it has been found that the reflectivity of the grating or the effectiveness of the grating in extracting the wavelength is 92-93%.

  13. NASA's Chandra Finds Black Holes Are "Green"

    Science.gov (United States)

    2006-04-01

    Black holes are the most fuel efficient engines in the Universe, according to a new study using NASA's Chandra X-ray Observatory. By making the first direct estimate of how efficient or "green" black holes are, this work gives insight into how black holes generate energy and affect their environment. The new Chandra finding shows that most of the energy released by matter falling toward a supermassive black hole is in the form of high-energy jets traveling at near the speed of light away from the black hole. This is an important step in understanding how such jets can be launched from magnetized disks of gas near the event horizon of a black hole. Illustration of Fuel for a Black Hole Engine Illustration of Fuel for a Black Hole Engine "Just as with cars, it's critical to know the fuel efficiency of black holes," said lead author Steve Allen of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University, and the Stanford Linear Accelerator Center. "Without this information, we cannot figure out what is going on under the hood, so to speak, or what the engine can do." Allen and his team used Chandra to study nine supermassive black holes at the centers of elliptical galaxies. These black holes are relatively old and generate much less radiation than quasars, rapidly growing supermassive black holes seen in the early Universe. The surprise came when the Chandra results showed that these "quiet" black holes are all producing much more energy in jets of high-energy particles than in visible light or X-rays. These jets create huge bubbles, or cavities, in the hot gas in the galaxies. Animation of Black Hole in Elliptical Galaxy Animation of Black Hole in Elliptical Galaxy The efficiency of the black hole energy-production was calculated in two steps: first Chandra images of the inner regions of the galaxies were used to estimate how much fuel is available for the black hole; then Chandra images were used to estimate the power required to produce

  14. Beyond Chandra - the X-ray Surveyor

    CERN Document Server

    Weisskopf, Martin C; Tananbaum, Harvey; Vikhlinin, Alexey

    2015-01-01

    Over the past 16 years, NASA's Chandra X-ray Observatory has provided an unparalleled means for exploring the universe with its half-arcsecond angular resolution. Chandra studies have deepened our understanding of galaxy clusters, active galactic nuclei, galaxies, supernova remnants, planets, and solar system objects addressing almost all areas of current interest in astronomy and astrophysics. As we look beyond Chandra, it is clear that comparable or even better angular resolution with greatly increased photon throughput is essential to address even more demanding science questions, such as the formation and subsequent growth of black hole seeds at very high redshift; the emergence of the first galaxy groups; and details of feedback over a large range of scales from galaxies to galaxy clusters. Recently, NASA Marshall Space Flight Center, together with the Smithsonian Astrophysical Observatory, has initiated a concept study for such a mission named the X-ray Surveyor. This study starts with a baseline payloa...

  15. Two-degree-of-freedom displacement measurement system based on double diffraction gratings

    Science.gov (United States)

    Lu, Zhengang; Wei, Peipei; Wang, Chaoqun; Jing, Jialei; Tan, Jiubin; Zhao, Xiping

    2016-07-01

    A two-degree-of-freedom (2-DOF) displacement measurement system based on double diffraction gratings is proposed in this paper, which consists of a reflective-type scale grating and a grating read head with a scanning transmission grating. Combining the traditional three-grating interference principle with the Michelson interference principle, the system can measure the displacements of a precision stage along the horizontal direction (X-axis, in the scanning grating plane and vertical to the scanning grating lines) and vertical direction (Z-axis, vertical to the scanning grating plane) simultaneously. The system has the merits of compact structure and uncoupled interference signals in the two axes. By simulating the output signals of the system and comparing them with the experimental results, the validity and feasibility of the system have been verified. The 2-DOF system will be favorable in the displacement measurement of multi-dimensional stages and multi-DOF machines.

  16. Chandra High-resolution Spectroscopy of the Circumnuclear Matter in the Broad-line Radio Galaxy 3C 445

    Science.gov (United States)

    Reeves, J. N.; Gofford, J.; Braito, V.; Sambruna, R.

    2010-12-01

    We present evidence for X-ray line emitting and absorbing gas in the nucleus of the broad-line radio galaxy 3C 445. A 200 ks Chandra Low Energy Transmission Grating observation of 3C 445 reveals the presence of several highly ionized emission lines in the soft X-ray spectrum, primarily from the He- and H-like ions of O, Ne, Mg, and Si. Radiative recombination emission is detected from O VII and O VIII, indicating that the emitting gas is photoionized. The He-like emission appears to be resolved into forbidden and intercombination line components, which implies a high density of >1010 cm-3, while the oxygen lines are velocity broadened with a mean width of ~2600 km s-1 (FWHM). The density and widths of the ionized lines indicate an origin of the gas on sub-parsec scales in the broad-line region. The X-ray continuum of 3C 445 is heavily obscured either by a partial coverer or by a photoionized absorber of column density N H = 2 × 1023 cm-2 and ionization parameter log ξ = 1.4 erg cm s-1. However, the view of the X-ray line emission is unobscured, which requires the absorber to be located at radii well within any parsec-scale molecular torus. Instead we suggest that the X-ray absorber in 3C 445 may be associated with an outflowing but clumpy accretion disk wind, with an observed outflow velocity of ~10, 000 km s-1.

  17. Investigation on multilayer microstructure grating for three-port splitting

    Science.gov (United States)

    Shu, Wenhao; Wang, Bo; Pei, Hao; Li, Hongtao; Chen, Li; Lei, Liang; Zhou, Jinyun

    2016-06-01

    A new structure of microstructure reflection three-port beam splitter grating is described in this paper. The grating includes two dielectric layers and a metal slab on the substrate, where incident waves are reflected into the zeroth-order and the ± first-order with polarization-independent property. With the optimized grating profile, reflection efficiencies’ ratios between the first-order and the zeroth-order can reach 0.998 and 1.001 for TE and TM polarizations, respectively. Especially, the reflection grating can diffract efficiencies more than 30% into the ± first-order and the zeroth-order with the incident angular bandwidth of ‑1.9-1.9∘ for TM polarization, which can have merits compared with single-layer transmission grating.

  18. Thomson scattering and collisional ionization in the X-ray grating spectra of the recurrent nova U Scorpii

    Science.gov (United States)

    Orio, M.; Behar, E.; Gallagher, J.; Bianchini, A.; Chiosi, E.; Luna, G. J. M.; Nelson, T.; Rauch, T.; Schaefer, B. E.; Tofflemire, B.

    2013-02-01

    We present a Chandra observation of the recurrent nova U Scorpii, done with the High Resolution camera-S (HRC-S) detector and the Low Energy Transmission Grating (LETG) on day 18 after the observed visual maximum of 2010, and compare it with XMM-Newton observations obtained on days 23 and 35 after maximum. The total absorbed flux was in the range 2.2-2.6 × 10-11 erg cm-2 s-1, corresponding to unabsorbed luminosity 7-8.5 × 1036 ×(d/12 kpc)2 for N(H) = 2-2.7 × 1021 cm-2. On day 18, 70 per cent of the soft X-tray flux was in a continuum typical of a very hot white dwarf (WD) atmosphere, which accounted for about 80 per cent of the flux on days 23 and 35. In addition, all spectra display very broad emission lines, due to higher ionization stages at later times. With Chandra we observed apparent P Cygni profiles. We find that these peculiar profiles are not due to blueshifted absorption and redshifted emission in photoionized ejecta, like the optical P Cyg of novae, but they are rather a superposition of WD atmospheric absorption features reflected by the already discovered Thomson scattering corona, and emission lines due to collisional ionization in condensations in the ejecta. On days 23 and 35, the absorption components were no longer measurable, having lost the initial large blueshift that displaced them from the core of the broad emission lines. We interpret this as an indication that mass-loss ceased between day 18 and day 23. On day 35, the emission line spectrum became very complex, with several different components. Model atmospheres indicate that the WD atmospheric temperature was about 730 000 K on day 18 and reached 900 000-1000 000 K on day 35. This peak temperature is consistent with a WD mass of at least 1.3 M⊙.

  19. The Chandra Source Catalog: Processing and Infrastructure

    Science.gov (United States)

    Evans, Janet; Evans, Ian N.; Glotfelty, Kenny J.; Hain, Roger; Hall, Diane M.; Miller, Joseph B.; Plummer, David A.; Zografou, Panagoula; Primini, Francis A.; Anderson, Craig S.; Bonaventura, Nina R.; Chen, Judy C.; Davis, John E.; Doe, Stephen M.; Fabbiano, Giuseppina; Galle, Elizabeth C.; Gibbs, Danny G., II; Grier, John D.; Harbo, Peter N.; He, Xiang Qun (Helen); Houck, John C.; Karovska, Margarita; Kashyap, Vinay L.; Lauer, Jennifer; McCollough, Michael L.; McDowell, Jonathan C.; Mitschang, Arik W.; Morgan, Douglas L.; Mossman, Amy E.; Nichols, Joy S.; Nowak, Michael A.; Refsdal, Brian L.; Rots, Arnold H.; Siemiginowska, Aneta L.; Sundheim, Beth A.; Tibbetts, Michael S.; van Stone, David W.; Winkelman, Sherry L.

    2009-09-01

    Chandra Source Catalog processing recalibrates each observation using the latest available calibration data, and employs a wavelet-based source detection algorithm to identify all the X-ray sources in the field of view. Source properties are then extracted from each detected source that is a candidate for inclusion in the catalog. Catalog processing is completed by matching sources across multiple observations, merging common detections, and applying quality assurance checks. The Chandra Source Catalog processing system shares a common processing infrastructure and utilizes much of the functionality that is built into the Standard Data Processing (SDP) pipeline system that provides calibrated Chandra data to end-users. Other key components of the catalog processing system have been assembled from the portable CIAO data analysis package. Minimal new software tool development has been required to support the science algorithms needed for catalog production. Since processing pipelines must be instantiated for each detected source, the number of pipelines that are run during catalog construction is a factor of order 100 times larger than for SDP. The increased computational load, and inherent parallel nature of the processing, is handled by distributing the workload across a multi-node Beowulf cluster. Modifications to the SDP automated processing application to support catalog processing, and extensions to Chandra Data Archive software to ingest and retrieve catalog products, complete the upgrades to the infrastructure to support catalog processing.

  20. Spectral analysis of the Chandra comet survey

    NARCIS (Netherlands)

    Bodewits, D.; Christian, D. J.; Torney, M.; Dryer, M.; Lisse, C. M.; Dennerl, K.; Zurbuchen, T. H.; Wolk, S. J.; Tielens, A. G. G. M.; Hoekstra, R.

    2007-01-01

    Aims. We present results of the analysis of cometary X-ray spectra with an extended version of our charge exchange emission model (Bodewits et al. 2006). We have applied this model to the sample of 8 comets thus far observed with the Chandra X-ray observatory and acis spectrometer in the 300 - 1000

  1. Holographic liquid crystal polarization grating with Fabry-Perot structure.

    Science.gov (United States)

    Sakamoto, Moritsugu; Yamaguchi, Haruki; Noda, Kohei; Sasaki, Tomoyuki; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2016-03-15

    A holographic liquid crystal polarization grating with a Fabry-Perot structure was developed. Because of its resonant structure, the device offers high levels of control of the diffraction properties of incident-polarized light beams, depending on the resonance conditions. The diffracted light beams are emitted in both the reflection and transmission directions, and the device thus works as a multibranch polarization grating with double optical paths, unlike a conventional polarization grating. These device features were experimentally demonstrated and were also explained theoretically.

  2. Chandra X-ray Observatory Optical Axis and Aimpoint

    Science.gov (United States)

    Zhao, Ping

    2016-01-01

    Chandra X-ray Observatory revolutionized the X-ray astronomy as being the first, and so far the only, X-ray telescope achieving sub-arcsecond resolution. Chandra comprises of three principal elements: the High Resolution Mirror Assembly (HRMA), Pointing Control and Aspect Determination (PCAD) system, and the Science Instrument Module (SIM). To achieve and retain the unprecedented imaging quality, it is critical that these three principal elements stay rigid and stable for the entire life time of the Chandra operation. Tracking the Chandra optical axis and aimpoint with respect to detector positions is the most relevant measurement for understanding telescope stability. The study shows that both the optical axis and the aimpoint has been drifting since Chandra launch. I will discuss the telescope focal-point, optical axis, aimpoint, their positiondrifts during the mission, the impact to Chandra operations, and the permanent default aimpoint, to be implemented in Chandra cycle 18.

  3. Fused-silica sandwiched three-port grating under second Bragg angle incidence

    Science.gov (United States)

    Li, Hongtao; Wang, Bo; Pei, Hao; Chen, Li; Lei, Liang; Zhou, Jinyun

    2016-05-01

    The fused-silica sandwiched three-port grating under second Bragg angle incidence is presented with operation in transmission. To obtain a highly-efficient three-port grating for a working wavelength of 800 nm, the grating depth and period should be optimized by using rigorous coupled-wave analysis. With the optimized different three-port grating depths and periods, both TE-polarized and TM-polarized waves can be diffracted into three orders with nearly 33% efficiency for the given duty cycle of 0.6. Based on the grating parameters of numerical optimization, modal method may be employed to explain the physical mechanism of the beam propagation in the grating and analyze the splitting behavior. For the sandwiched three-port grating, it is feasible that the diffraction efficiencies can be enhanced for both TE and TM polarizations.

  4. Chandra hardware and systems: keeping things running

    Science.gov (United States)

    Paton, Lisa

    2006-06-01

    System management for any organization can be a challenge, but satellite projects present their own issues. I will be presenting the network and system architecture chosen to support the scientists in the Chandra X-ray Center. My group provides the infrastructure for science data processing, mission planning, user support, archive support and software development. Our challenge is to create a stable environment with enough flexibility to roll with the changes during the mission. I'll discuss system and network choices, web service, backups, security and systems monitoring. Also, how to build infrastructure that's flexible, how to support a large group of scientists with a relatively small staff, what challenges we faced (anticipated and unanticipated) and what lessons we learned over the past 6 years since the launch of Chandra. Finally I'll outline our plans for the future including beowulf cluster support, an improved helpdesk system, methods for dealing with the explosive amount of data that needs to be managed.

  5. Karakterisasi Fiber Bragg Grating (FBG) Untuk Pengembangan Sistem Sensor Strain Tanah

    OpenAIRE

    Sinuhaji, Depi Santi

    2010-01-01

    Fiber Bragg Grating (FBG) is a periodic change of refractive index which is the length of optical fiber. Has been developed Fiber Bragg Grating (FBG)-based laser diodes for monitoring landslide-prone areas. This sensor has been developed because high sensitivity and is not affected by electromagnetic induction that can be placed at a distance from the location where the power supply and monitor. FBG transmission peak will shift when the grating is change resulting from a change in temperature...

  6. Numerical Analysis of Thermal Dependence of the Spectral Response of Polymer Optical Fiber Bragg Gratings

    OpenAIRE

    Hisham K. Hisham

    2016-01-01

    The thermal dependence of the spectral response (i.e. transmission, reflection and time delay (r) responses) of uniform polymer optical fiber (POF) Bragg gratings has been investigated. In addition to the temperature dependence, the effects of grating strength (kLg) and fiber index modulation (n) have been investigated. Besides high capability of tunable wavelength due to the unique large and negative thermo-optic coefficient of POF, the spectral response for POF Bragg gratings sh...

  7. Influence of Non-uniform Temperature Field on Spectra of Fibre Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yan; HE Xing-Fang; YUAN Jie; YIN Li-Qun; FANG Xiao-Yong; CAO Mao-Sheng

    2009-01-01

    We simulate the spectrum characteristics of fibre Bragg grating (FBG) with non-uniform temperature using the transmission matrix method, and the results are analysed. It is found that firstly the modulated coefficient of average refractive index is a very important parameter that influences the spectrum characteristic of the fibre Bragg grating, and secondly the spectrum curves are different in different temperature fields at the same parameter. Hence, we can determine the metrical temperature by analysing the spectrum of fibre Bragg grating.

  8. Application of Metallic Strip Gratings for Enhancement of Electromagnetic Performance of A-sandwich Radome

    OpenAIRE

    Raveendranath U. Nair; J. Madhumitha; R. M. Jha

    2013-01-01

    Enhancement of the electromagnetic (EM) performance characteristics of A-sandwich radome wall over X-band using metallic strip gratings is presented in this work. Equivalent transmission line method in conjunction with equivalent circuit model (ECM) is used for modeling the A-sandwich radome panel with metallic strip gratings and the computation of radome performance parameters. Metallic strip grating embedded in the mid-plane of the core and those in the skin-core interface are the configura...

  9. Research on the polarization and temperature characteristics of subwavelength aluminum gratings

    International Nuclear Information System (INIS)

    An aluminum grating with period of 152 nm is designed and manufactured based on rigorous coupled wave analysis. Its transmissions of TM and TE waves are measured at 532 nm, 632.8 nm and 810 nm, respectively. From the agreement between the experimental results and simulations, a grating thickness of 80 ± 5 nm can be determined. The analysis of and experiments on the grating temperature dependence reveal its thermal stability in ambient conditions. (paper)

  10. Tutorial: Applications of Fibre Gratings

    Institute of Scientific and Technical Information of China (English)

    Hwayaw; Tam; Bai; ou; Guan; Shunyee; Liu

    2003-01-01

    Fibre grating is an important enabling technology that has found numerous applications in both telecommunications and sensor systems. This tutorial describes the basic characteristics of fibre gratings and gives examples of where they are being employed.

  11. Integral Method for Gratings

    CERN Document Server

    Maystre, Daniel

    2014-01-01

    The chapter contains a detailed presentation of the surface integral theory for modelling light diffraction by surface-relief diffraction gratings having a one-dimensional periodicity. Several different approaches are presented, leading either to a single integral equation, or to a system of coupled integral equations. Special attention is paid to the singularities of the kernels, and to different techniques to accelerate the convergence of the numerical computations. The theory is applied to gratings having different profiles with or without edges, to real metal and dielectrics, and to perfectly conducting substrates.

  12. Ultra-High Temperature Gratings

    Institute of Scientific and Technical Information of China (English)

    John Canning; Somnath Bandyopadhyay; Michael Stevenson; Kevin Cook

    2008-01-01

    Regenerated gratings seeded by type-Ⅰ gratings are shown to withstand temperatures beyond 1000 ℃. The method of regeneration offers a new approach to increasing temperature resistance of stable fibre Bragg and other gratings. These ultra-high temperature (UHT) gratings extend the applicability of silicate based components to high temperature applications such as monitoring of smelters and vehicle and aircraft engines to high power fibre lasers.

  13. Holographic diffraction gratings as laser radiation protection filters

    Energy Technology Data Exchange (ETDEWEB)

    Pantelic, D. [Institute of Physics, Zemun, Belgrade, Serbia and Montenegro (Serbia); Pantelic, G. [Institute of occupational health and radiation protection, Belgrade, Serbia and Montenegro (Serbia)

    2006-07-01

    Holographic volume diffraction gratings are used as attenuation filters, due to their selective spectral transmission. They can be tailored to reflect or transmit narrow spectral ranges by adjusting spatial frequency of Bragg grating in carefully chosen photosensitive materials, like silver-halide emulsion or di-chromated gelatin layers. If properly recorded and chemically processed, resulting gratings can significantly attenuate light at wavelengths corresponding to various laser spectral lines. Thus, they can be used as filters in laser protection goggles. We analyze the characteristics of Bragg gratings necessary to obtain high attenuation coefficients. Also, their angular selectivity is taken into account and corresponding experimental conditions are investigated. Although di-chromated gelatin seems to be almost ideal material, due to its almost 100% diffraction efficiency, environmental stability is poor (degradation under humid environment), thus making its practical usage difficult. Thus, we have analyzed alternative materials like di-chromated pullulan, which is stable under normal environmental conditions (without drop in diffraction efficiency after prolonged exposure to humidity). Pullulan is polymer (polysaccharide) of biologic origin produced by certain bacteria. If doped with chromium ions it becomes photosensitive, enabling recording of diffraction gratings with spatial frequency of more than 3000 lines/mm. Material is chemically processed by mixture of isopropyl alcohol and water. Both thick and thin layers can be produced by gravity settling. Spectral properties of resulting gratings are analyzed, showing that they can significantly attenuate laser light of particular wavelength, depending of grating period and its slant angle. (authors)

  14. [Diffraction gratings used in x-ray spectroscopy]: Final report

    International Nuclear Information System (INIS)

    This subcontract was initiated in order to facilitate the development at MIT of technologies for fabricating the very fine diffraction grating required in x-ray spectroscopy at Lawrence Livermore Laboratory (LLL). These gratings are generally gold transmission gratings with spatial periods of 200 nm or less. The major focus of our efforts was to develop a means of fabricating gratings of 100 nm period. We explored two approaches: e-beam fabrication of x-ray lithography masks, and achromatic holographic lithography. This work was pursued by Erik Anderson as a major component of his Ph.D. thesis. Erik was successful in both the e-beam and holographic approaches. However, the e-beam method proved to be highly impractical: exposure times of about 115 days would be required to cover an area of 1 cm2. The achromatic holography, on the other hand, should be capable of exposing areas well in excess of 1 cm2 in times under 1 hour. Moreover, 100 nm-period gratings produced by achromatic holography are coherent over their entire area whereas gratings produced by e-beam lithography are coherent only over areas /approximately/100 μm. The remainder of this report consists of portions excerpted from Erik Anderson's thesis. These contain all the details of our work on 100 nm period gratings. 26 refs., 17 figs

  15. Contributions of the NASA's Chandra X-Ray Observatory

    Science.gov (United States)

    Weisskopf, Martin C.

    2011-01-01

    NASA's Chandra X-ray Observatory performed its first observations over a decade ago. Chandra's spectacular images and detailed spectra of astrophysical systems ranging from solar system objects to distant galaxies and galaxy clusters have provided information on such diverse topics as the properties of planetary and cometary atmospheres, stellar formation and demise, black hole-galaxy-cluster interactions, and properties of dark matter and dark energy. This presentation highlights some discoveries made with Chandra and briefly discusses future prospects.

  16. Chandra Catches Cannibal Galaxy in the Act

    Science.gov (United States)

    2000-07-01

    NASA's Chandra X-ray Observatory image of Perseus A provides new insight into how this supergiant galaxy has grown by cannibalizing other galaxies and gas in the vicinity. For the first time astronomers see an X-ray shadow cast by a smaller galaxy as its gas is being stripped away by the enormous galaxy. The research was reported by Professor Andrew Fabian of the Institute of Astronomy, Cambridge, England on June 7 at the 196th National Meeting of the American Astronomical Society, in Rochester, NY. Other members of the research team are Jeremy Sanders, Stefano Ettori, Steve Allen, Carolin Crawford, Kazushi Iwasawa, and Roderick Johnstone of the Institute of Astronomy, Gregory Taylor on the National Radio Astronomy Observatory, Socorro, NM, and Patrick Ogle of the Massachusetts Institute of Technology, Cambridge, MA. Perseus A, or NGC 1275, is in the center of a large galaxy cluster 320 million light years from Earth. The cluster, which contains thousands of galaxies and enough gas to make thousands more, is one of the largest gravitationally bound objects in the universe. Over the eons, Perseus A has accumulated hundreds of billions of stars to become one of the most massive known galaxies as gas and galaxies have been pulled inward by gravity. The Chandra observation shows a region of hot gas that extends over several hundred thousand light years. The gas in the outer portion of the cluster has a temperature of 70 million degrees. The cluster gas cools gradually and settles toward the center of the cluster. A galaxy with "only" about 20 billion stars is falling into Perseus A (located at two o'clock from the center of the image) and appears as a small dark patch due to absorption of X rays by cool gas in the infalling galaxy. Another larger hole seen further out is thought to be due to a bubble of high-energy particles ejected in an explosion from Perseus A hundreds of millions of years ago. These outbursts are presumably fueled by matter releasing tremendous

  17. Chandra HETGS Multi-Phase Spectroscopy of the Young Magnetic O Star theta^1 Orionis C

    CERN Document Server

    Gagné, M; MacFarlane, J J; Oksala, M E; Owocki, S P; Tonnesen, S K; Townsend, R H D; ud-Doula, A; Cohen, David H.; Farlane, Joseph J. Mac; Gagne, Marc; Oksala, Mary E.; Owocki, Stanley P.; Tonnesen, Stephanie K.; Townsend, Richard H. D.; ud-Doula, Asif

    2005-01-01

    We report on four Chandra grating observations of the oblique magnetic rotator theta^1 Ori C (O5.5 V) covering a wide range of viewing angles with respect to the star's 1060 G dipole magnetic field. We employ line-width and centroid analyses to study the dynamics of the X-ray emitting plasma in the circumstellar environment, as well as line-ratio diagnostics to constrain the spatial location, and global spectral modeling to constrain the temperature distribution and abundances of the very hot plasma. We investigate these diagnostics as a function of viewing angle and analyze them in conjunction with new MHD simulations of the magnetically channeled wind shock mechanism on theta^1 Ori C. This model fits all the data surprisingly well, predicting the temperature, luminosity, and occultation of the X-ray emitting plasma with rotation phase.

  18. Coherently controlling Raman-induced grating in atomic media

    CERN Document Server

    Arkhipkin, V G; Timofeev, I V

    2015-01-01

    We consider dynamically controllable periodic structures, called Raman induced gratings, in three- and four-level atomic media, resulting from Raman interaction in a standing-wave pump. These gratings are due to periodic spatial modulation of the Raman nonlinearity and fundamentally differ from the ones based on electromagnetically induced transparency. The transmission and reflection spectra of such gratings can be simultaneously amplified and controlled by varying the pump field intensity. It is shown that a transparent medium with periodic spatial modulation of the Raman gain can be opaque near the Raman resonance and yet at the same time it can be a non-linear amplifying mirror. We also show that spectral properties of the Raman induced grating can be controlled with the help of an additional weak control field.

  19. Imaging properties of high aspect ratio absorption gratings for use in preclinical x-ray grating interferometry

    Science.gov (United States)

    Trimborn, Barbara; Meyer, Pascal; Kunka, Danays; Zuber, Marcus; Albrecht, Frederic; Kreuer, Sascha; Volk, Thomas; Baumbach, Tilo; Koenig, Thomas

    2016-01-01

    X-ray grating interferometry is one among various methods that allow extracting the so-called phase and visibility contrasts in addition to the well-known transmission images. Crucial to achieving a high image quality are the absorption gratings employed. Here, we present an in-depth analysis of how the grating type and lamella heights influence the final images. Benchmarking gratings of two different designs, we show that a frequently used proxy for image quality, a grating’s so-called visibility, is insufficient to predict contrast-to-noise ratios (CNRs). Presenting scans from an excised rat lung, we demonstrate that the CNRs obtained for transmission and visibility images anti-correlate. This is explained by the stronger attenuation implied by gratings that are engineered to provide high visibilities by means of an increased lamella height. We show that even the visibility contrast can suffer from this effect when the associated reduced photon flux on the detector is not outweighed by a corresponding gain in visibility. Resulting in an inevitable trade-off between the quality of the two contrasts, the question of how an optimal grating should be designed can hence only be answered in terms of Pareto optimality.

  20. Bragg grating rogue wave

    CERN Document Server

    Degasperis, Antonio; Aceves, Alejandro B

    2015-01-01

    We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing, may lead to extreme waves at extremely low powers.

  1. Bragg grating rogue wave

    Energy Technology Data Exchange (ETDEWEB)

    Degasperis, Antonio [Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma (Italy); Wabnitz, Stefan, E-mail: stefan.wabnitz@unibs.it [Dipartimento di Ingegneria dell' Informazione, Università degli Studi di Brescia and INO-CNR, via Branze 38, 25123 Brescia (Italy); Aceves, Alejandro B. [Southern Methodist University, Dallas (United States)

    2015-06-12

    We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing may lead to extreme waves at extremely low powers.

  2. A Chandra HETGS observation of the Narrow-line Seyfert 1 galaxy Ark 564

    CERN Document Server

    Matsumoto, C; Marshall, H L; Matsumoto, Chiho; Leighly, Karen M.; Marshall, Herman L.

    2004-01-01

    We present results from a 50 ks observation of the narrow-line Seyfert 1 galaxy Ark 564 with the Chandra HETGS. The spectra above 2 keV are modeled by a power-law with a photon-index of 2.56+/-0.06. We confirm the presence of the soft excess below about 1.5 keV. If we fit the excess with blackbody model, the best-fit temperature is 0.124 keV. Ark 564 has been reported to show a peculiar emission line-like feature at 1 keV in various observations using lower resolution detectors, and the Chandra grating spectroscopy rules out an origin of blends of several narrow emission lines. We detect an edge-like feature at 0.712 keV in the source rest frame. The preferred interpretation of this feature is combination of the O VII K-edge and a number of L-absorption lines from slightly ionized iron, which suggests a warm absorber with ionization parameter xi~1 and N_H ~ 10^21 cm^-2. These properties are roughly consistent with those of the UV absorber. We also detect narrow absorption lines of O VII, O VIII, Ne IX, Ne X, ...

  3. Numerical Analysis of Fiber Bragg Grating and Long Period Fiber Grating Undergoing Linear and Quadratic Temperature Change

    Institute of Scientific and Technical Information of China (English)

    YUAN Yinquan; DING Liyun

    2009-01-01

    The coupled-mode equations for fiber Bragg grating(FBG)and long period fiber grating(LPFG)undergoing linear and quadratic temperature change were given.The effects of tem-perature gradient and quadratic temperature change on the reflectivity spectrum of fiber Braggs grating and the transmission spectrum of long period fiber grating were investigated using the numerical simulation,and the dependence relationships of the central wavelength shift,the full-width-at-half-maximum,and the peak intensity upon temperature gradient were also obtained.These relation-ships may be used to design a novel fiber optical sensor which can simultaneously measure the tem-perature and temperature gradient.

  4. CHANDRA VIEW OF THE WARM-HOT INTERGALACTIC MEDIUM TOWARD 1ES 1553+113: ABSORPTION-LINE DETECTIONS AND IDENTIFICATIONS. I

    Energy Technology Data Exchange (ETDEWEB)

    Nicastro, F.; Zappacosta, L. [Osservatorio Astronomico di Roma-INAF, Via di Frascati 33, I-00040 Monte Porzio Catone, RM (Italy); Elvis, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS-04, Cambridge, MA 02138 (United States); Krongold, Y. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Mexico City Mexico (Mexico); Mathur, S.; Gupta, A. [Ohio State University, Columbus, OH (United States); Danforth, C.; Shull, J. M. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Barcons, X. [Instituto de Fisica de Cantabria (CSIC-UC), E-39005 Santander (Spain); Borgani, S. [Dipartimento di Astronomia dell' Universita di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste (Italy); Branchini, E. [Dipartimento di Fisica ' ' E. Amaldi' ' , Universita degli Studi ' ' Roma Tre' ' , via della Vasca Navale 84, I-00146 Roma (Italy); Cen, R. [Princeton University Observatory, Princeton, NJ 08544 (United States); Dave, R. [Astronomy Department, University of Arizona, Tucson, AZ 85721 (United States); Kaastra, J. [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht (Netherlands); Paerels, F. [Columbia Astrophysics Laboratory and Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Piro, L. [INAF-IAPS, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Takei, Y. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

    2013-06-01

    We present the first results from our pilot 500 ks Chandra Low Energy Transmission Grating Large Program observation of the soft X-ray brightest source in the z {approx}> 0.4 sky, the blazar 1ES 1553+113, aimed to secure the first uncontroversial detections of the missing baryons in the X-rays. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2{sigma} and 4.1{sigma}. Six of these lines are detected at high single-line statistical significance (3.6 {<=} {sigma} {<=} 4.1), while the remaining five are regarded as marginal detections in association with either other X-ray lines detected at higher significance and/or far-ultraviolet (FUV) signposts. Three of these lines are consistent with metal absorption at z {approx_equal} 0, and we identify them with Galactic O I and C II. The remaining eight lines may be imprinted by intervening absorbers and are all consistent with being high-ionization counterparts of FUV H I and/or O VI intergalactic medium signposts. In particular, five of these eight possible intervening absorption lines (single-line statistical significances of 4.1{sigma}, 4.1{sigma}, 3.9{sigma}, 3.8{sigma}, and 2.7{sigma}), are identified as C V and C VI K{alpha} absorbers belonging to three WHIM systems at z{sub X} = 0.312, z{sub X} = 0.237, and (z{sub X} ) = 0.133, which also produce broad H I (and O VI for the z{sub X} = 0.312 system) absorption in the FUV. For two of these systems (z{sub X} = 0.312 and 0.237), the Chandra X-ray data led the a posteriori discovery of physically consistent broad H I associations in the FUV (for the third system the opposite applies), so confirming the power of the X-ray-FUV synergy for WHIM studies. The true statistical significances of these three X-ray absorption systems, after properly accounting for the number of redshift trials, are 5.8{sigma} (z{sub X} = 0.312; 6.3{sigma} if the low-significance O V and C V K{beta} associations are considered), 3.9{sigma} (z

  5. Chandra View of the Warm-hot Intergalactic Medium toward 1ES 1553+113: Absorption-line Detections and Identifications. I.

    Science.gov (United States)

    Nicastro, F.; Elvis, M.; Krongold, Y.; Mathur, S.; Gupta, A.; Danforth, C.; Barcons, X.; Borgani, S.; Branchini, E.; Cen, R.; Davé, R.; Kaastra, J.; Paerels, F.; Piro, L.; Shull, J. M.; Takei, Y.; Zappacosta, L.

    2013-06-01

    We present the first results from our pilot 500 ks Chandra Low Energy Transmission Grating Large Program observation of the soft X-ray brightest source in the z >~ 0.4 sky, the blazar 1ES 1553+113, aimed to secure the first uncontroversial detections of the missing baryons in the X-rays. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2σ and 4.1σ. Six of these lines are detected at high single-line statistical significance (3.6 X-ray lines detected at higher significance and/or far-ultraviolet (FUV) signposts. Three of these lines are consistent with metal absorption at z ~= 0, and we identify them with Galactic O I and C II. The remaining eight lines may be imprinted by intervening absorbers and are all consistent with being high-ionization counterparts of FUV H I and/or O VI intergalactic medium signposts. In particular, five of these eight possible intervening absorption lines (single-line statistical significances of 4.1σ, 4.1σ, 3.9σ, 3.8σ, and 2.7σ), are identified as C V and C VI Kα absorbers belonging to three WHIM systems at zX = 0.312, zX = 0.237, and langzX rang = 0.133, which also produce broad H I (and O VI for the zX = 0.312 system) absorption in the FUV. For two of these systems (zX = 0.312 and 0.237), the Chandra X-ray data led the a posteriori discovery of physically consistent broad H I associations in the FUV (for the third system the opposite applies), so confirming the power of the X-ray-FUV synergy for WHIM studies. The true statistical significances of these three X-ray absorption systems, after properly accounting for the number of redshift trials, are 5.8σ (zX = 0.312; 6.3σ if the low-significance O V and C V Kβ associations are considered), 3.9σ (zX = 0.237), and 3.8σ (langzX rang = 0.133), respectively.

  6. ASA's Chandra Neon Discovery Solves Solar Paradox

    Science.gov (United States)

    2005-07-01

    NASA's Chandra X-ray Observatory survey of nearby sun-like stars suggests there is nearly three times more neon in the sun and local universe than previously believed. If true, this would solve a critical problem with understanding how the sun works. "We use the sun to test how well we understand stars and, to some extent, the rest of the universe," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "But in order to understand the sun, we need to know exactly what it is made of," he added. It is not well known how much neon the sun contains. This is critical information for creating theoretical models of the sun. Neon atoms, along with carbon, oxygen and nitrogen, play an important role in how quickly energy flows from nuclear reactions in the sun's core to its edge, where it then radiates into space. Chandra X-ray Spectrum of II Pegasi Chandra X-ray Spectrum of II Pegasi The rate of this energy flow determines the location and size of a crucial stellar region called the convection zone. The zone extends from near the sun's surface inward approximately 125,000 miles. The zone is where the gas undergoes a rolling, convective motion much like the unstable air in a thunderstorm. "This turbulent gas has an extremely important job, because nearly all of the energy emitted at the surface of the sun is transported there by convection," Drake said. The accepted amount of neon in the sun has led to a paradox. The predicted location and size of the solar convection zone disagree with those deduced from solar oscillations. Solar oscillations is a technique astronomers previously relied on to probe the sun's interior. Several scientists have noted the problem could be fixed if the abundance of neon is in fact about three times larger than currently accepted. Attempts to measure the precise amount of neon in the Sun have been frustrated by a quirk of nature; neon atoms in the Sun give off no signatures in visible light. However, in a gas

  7. The Chandra Delta Ori Large Project: Occultation Measurements of the Shocked Gas tn the Nearest Eclipsing O-Star Binary

    Science.gov (United States)

    Corcoran, Michael F.; Nichols, Joy; Naze, Yael; Rauw, Gregor; Pollock, Andrew; Moffat, Anthony; Richardson, Noel; Evans, Nancy; Hamaguchi, Kenji; Oskinova, Lida; Hamann, W. -R.; Gull, Ted; Ignace, Rico; Hole, Tabetha; Iping, Rosina; Walborn, Nolan; Hoffman, Jennifer; Lomax, Jamie; Waldron, Wayne; Owocki, Stan; Maiz-Apellaniz, Jesus; Leutenegger, Maurice; Hole, Tabetha; Gayley, Ken; Russell, Chris

    2013-01-01

    Delta Ori is the nearest massive, single-lined eclipsing binary (O9.5 II + B0.5III). As such it serves as a fundamental calibrator of the mass-radius-luminosity relation in the upper HR diagram. It is also the only eclipsing O-type binary system which is bright enough to be observable with the CHANDRA gratings in a reasonable exposure. Studies of resolved X-ray line complexes provide tracers of wind mass loss rate and clumpiness; occultation by the X-ray dark companion of the line emitting region can provide direct spatial information on the location of the X-ray emitting gas produced by shocks embedded in the wind of the primary star. We obtained phase-resolved spectra with Chandra in order to determine the level of phase-dependent vs. secular variability in the shocked wind. Along with the Chandra observations we obtained simultaneous photometry from space with the Canadian MOST satellite to help understand the relation between X-ray and photospheric variability.

  8. Coronal density diagnostics with Helium-like triplets CHANDRA--LETGS observations of Algol, Capella, Procyon, Eps Eri, Alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR1099

    CERN Document Server

    Ness, J U; Burwitz, V; Mewe, R; Raassen, A J J; Van der Meer, R L J; Predehl, P; Brinkman, A C

    2002-01-01

    We present an analysis of ten cool stars (Algol, Capella, Procyon, Eps Eri, Alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR1099) observed with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory. This sample contains all cools stars observed with the LETGS presently available to us with integration times sufficiently long to warrant a meaningful spectral analysis. Our sample comprises inactive, moderately active, and hyperactive stars and samples the bulk part of activity levels encountered in coronal X-ray sources. We use the LETGS spectra to carry out density and temperature diagnostics with an emphasis on the H-like and the He-like ions. We find a correlation between line flux ratios of the Lyman-Alpha and He-like resonance lines with the mean X-ray surface flux. We determine densities using the He-like triplets. For active stars we find no significant deviations from the low-density limit for the ions of Ne, Mg, and Si, while the measured line ratios for the i...

  9. Chandra X-Ray Spectroscopy of the Focused Wind in the Cygnus X-1 System. II. The Nondip Spectrum in the Low/Hard State - Modulations with Orbital Phase

    CERN Document Server

    Miškovičová, Ivica; Hanke, Manfred; Nowak, Michael A; Pottschmidt, Katja; Schulz, Norbert S; Grinberg, Victoria; Duro, Refiz; Madej, Oliwia K; Lohfink, Anne M; Rodriguez, Jérôme; Bel, Marion Cadolle; Bodaghee, Arash; Tomsick, John A; Lee, Julia C; Brown, Gregory V; Wilms, Jörn

    2016-01-01

    The accretion onto the black hole in the system HDE 226868/Cygnus X-1 is powered by the strong line driven stellar wind of the O-type donor star. We study the X-ray properties of the stellar wind in the hard state of Cyg X-1 as determined with data from the Chandra High Energy Transmission Gratings. Large density and temperature inhomogeneities are present in the wind, with a fraction of the wind consisting of clumps of matter with higher density and lower temperature embedded in a photoionized gas. Absorption dips observed in the light curve are believed to be caused by these clumps. This work concentrates on the non-dip spectra as a function of orbital phase. The spectra show lines of H-like and He-like ions of S, Si, Na, Mg, Al and highly ionized Fe (Fe xvii-Fe xxiv). We measure velocity shifts, column densities, and thermal broadening of the line series. The excellent quality of these five observations allows us to investigate the orbital phase dependence of these parameters. We show that the absorber is ...

  10. Si3N4 Grated Waveguide Optical Cavity based Sensors for Bulk-index Concentration, Label-free Protein, and Mechano-Optical Gas Sensing

    NARCIS (Netherlands)

    Pham, S.V.; Dijkstra, M.; Hollink, A.J.F.; Ridder, de R.M.; Pollnau, M.; Hoekstra, H.J.W.M.

    2011-01-01

    A grated waveguide (GWG), which is a waveguide with a finite-length grated section, acts as an optical resonator, showing sharp fringes in the transmission spectrum near the stop-band edges of the grating. These oscillations are due to Fabry-Perot resonances of Bloch modes propagating in the cavity

  11. Fabrication of Dual-Wavelength Fiber Bragg Grating with a Longitudinal Stretch

    Institute of Scientific and Technical Information of China (English)

    JIANG Li; ZHANG Dong-sheng; ZHANG Wei-gang; KAI Gui-yun; DONG Xiao-yi

    2006-01-01

    A method of fabricating dual-wavelength fiber Bragg grating with a uniform phase mask is demonstrated.Theoretical analysis and numerical simulation using Matrix method arc given.The moving exposing technique is adopted.Good control over the grating's reflectivity and the separation of the two Bragg wavelengths is enabled by adjusting the stretch,the length of the grating,and the exposure.A grating with two equal transmission peaks of 19.5 dB is obtained by using this method,and the separation of the two Bragg wavelengths is 0.78 nm.

  12. Voltage-controlled compression for period tuning of optical surface relief gratings.

    Science.gov (United States)

    Kollosche, Matthias; Döring, Sebastian; Stumpe, Joachim; Kofod, Guggi

    2011-04-15

    This Letter reports on new methods and a consistent model for voltage tunable optical transmission gratings. Elastomeric gratings were molded from holographically written surface relief gratings in an azobenzene sol-gel material. These were placed on top of a transparent electroactive elastomeric substrate. Two different electro-active substrate elastomers were employed, with a large range of prestretches. A novel finite-deformation theory was found to match the device response excellently, without fitting parameters. The results clearly show that the grating underwent pure-shear deformation, and more surprisingly, that the mechanical properties of the electro-active substrate did not affect device actuation.

  13. Calculation of optical-waveguide grating characteristics using Green's functions and Dyson's equation

    DEFF Research Database (Denmark)

    Rindorf, Lars Henning; Mortensen, Asger

    2006-01-01

    We present a method for calculating the transmission spectra, dispersion, and time delay characteristics of optical-waveguide gratings based on Green's functions and Dyson's equation. Starting from the wave equation for transverse electric modes we show that the method can solve exactly both...... the problems of coupling of counterpropagating waves (Bragg gratings) and co-propagating waves (long-period gratings). In both cases the method applies for gratings with arbitrary dielectric modulation, including all kinds of chirp and apodization and possibly also imperfections in the dielectric modulation...

  14. Resonant THz sensor for paper quality monitoring using THz fiber Bragg gratings

    CERN Document Server

    Yan, Guofeng; Mikulic, Predrag; Bock, Wojtek J; Skorobogatiy, Maksim

    2013-01-01

    We report fabrication of THz fiber Bragg gratings (TFBG) using CO2 laser inscription on subwavelength step-index polymer fibers. A fiber Bragg grating with 48 periods features a ~4 GHz-wide stop band and ~15 dB transmission loss in the middle of a stop band. The potential of such gratings in design of resonant sensor for monitoring of paper quality is demonstrated. Experimental spectral sensitivity of the TFBG-based paper thickness sensor was found to be ~ -0.67 GHz / 10 um. A 3D electromagnetic model of a Bragg grating was used to explain experimental findings.

  15. The BMW-Chandra Serendipitous Source Catalog

    Science.gov (United States)

    Romano, P.; Campana, S.; Mignani, R. P.; Moretti, A.; Mottini, M.; Panzera, M. R.; Tagliaferri, G.

    2004-08-01

    We present the BMW-Chandra source catalog drawn from all Chandra ACIS-I pointed observations with an exposure time in excess of 10 ks public as of March 2003 (136 observations). Using the wavelet detection algorithm developed by Lazzati et al. (1999) and Campana et al. (1999), which can characterize point-like as well as extended sources, we identified 21325 sources. Among them, 16758 are serendipitous, i.e. not associated with the targets of the pointings, and do not require a non-automated analysis. This makes our catalog the largest compilation of Chandra sources to date. The 0.5--10 keV absorption corrected fluxes of these sources range from ˜ 3× 10-16 to 9×10-12 erg cm-2 s-1 with a median of 7× 10-15 erg cm-2 s-1. The catalog consists of count rates and relative errors in three energy bands (total, 0.5--7 keV; soft, 0.5--2 keV; and hard band, 2--7 keV), and source positions relative to the highest signal-to-noise detection among the three bands. The wavelet algorithm also provides an estimate of the extension of the source which we refined with a σ -clipping method. We report on the main properties of the sources in our catalog, such as sky coverage ( ˜ 8 deg2 at a limiting flux of ˜ 10-13 erg cm-2 s-1) and cosmological log N--log S for a subset at high Galactic latitude (∣ b ∣ > 20o) for a flux as low as ˜ 1.5 × 10-15 erg cm-2 s-1. Support for this work was provided by the Italian MIUR.

  16. Swift J1644+57: Chandra observations

    Science.gov (United States)

    Levan, A. J.; Tanvir, N. R.

    2012-11-01

    We observed the X-ray counterpart to the candidate relativistic tidal disruption event Swift J1644+57 (Levan et al. 2011 Science, 333 199; Bloom et al. 2011 Science 333 202; Burrows et al. 2011 Nature 476 421; Zauderer et al. 2011 Nature 476 425) with the Chandra X-ray Observatory, beginning on 26 November 2012 at 10:25 UT. A total integration of 24.7 ks was obtained, and the object was placed at the default position on the ACIS S3 chip.

  17. Parameters optimization of π-phase-shifted long-period fiber grating for gas sensing

    Institute of Scientific and Technical Information of China (English)

    JIANG Xiu-li; GU Zheng-tian

    2011-01-01

    @@ The gas-sensitive film coated π-phase-shifted long-period fiber grating (LPFG), consisting of two same long-period fiber gratings cascaded by a regular fiber with length of half of the grating period, is proposed for gas sensing.The sensitivity of the sensor is defined by the change rate of the transmission at specific wavelength with respect to the film refractive index.The qualitative and numerical analyses show that to get a high sensitivity, the optimal coupling strength of each long-period fiber grating is√2π/4 .With this coupling strength, the longer the grating is, the higher sensitivity the sensor has.By choosing appropriate grating period, a high sensitivity for the film with a certain refractive index and thickness can be attained.

  18. Free water in fuel sensor using fiber long period grating

    Science.gov (United States)

    Zhang, W.; Grice, S.; Sugden, K.; Bennion, I.

    2011-05-01

    A fiber optic free water in fuel (WIF) sensor is proposed by utilizing a long period fiber grating (LPFG). The existence of free water in fuel is indicated by the appearance of a characteristic loss band. The free water level in fuel can be determined by measuring the transmissions of two characteristic loss bands.

  19. Enhanced resolution of long-period grating bend sensor

    DEFF Research Database (Denmark)

    Glavind, Lars; Gao, S; Cook, K;

    2013-01-01

    We present an optical fiber bend sensor with enhanced resolution based on the principle of a Mach-Zehnder interferometer in transmission. The sensor is based on two identical Long-Period Gratings separated by approximately 100 mm in a D-shaped single-mode optical fiber. The sensor provides a narrow...

  20. Chandra Observations of SNR RCW 103

    CERN Document Server

    Frank, Kari A; Park, Sangwook

    2015-01-01

    We analyze three Chandra observations, with a combined exposure time of 99 ks, of the Galactic supernova remnant RCW 103, a young supernova remnant, previously with no clear detection of metal-rich ejecta. Based on our imaging and spectral analyses of these deep Chandra data, we find evidence for metal-rich ejecta emission scattered throughout the remnant. X-ray emission from the shocked ejecta is generally weak, and the shocked circumstellar medium (CSM) is a largely dominant component across the entire remnant. The CSM component shows abundances of ~0.5 solar, while Ne, Mg, Si, S, and Fe abundances of the ejecta are up to a few times solar. Comparison of these ejecta abundances with yields from supernova nucleosynthesis models suggests, together with the existence of a central neutron star, a progenitor mass of ~18-20 M$_\\odot$, though the Fe/Si ratios are larger than predicted. The shocked CSM emission suggests a progenitor with high mass-loss rate and subsolar metallicity.

  1. Chandra mission scheduling on-orbit experience

    Science.gov (United States)

    Bucher, Sabina; Williams, Brent; Pendexter, Misty; Balke, David

    2008-07-01

    Scheduling observatory time to maximize both day-to-day science target integration time and the lifetime of the observatory is a formidable challenge. Furthermore, it is not a static problem. Of course, every schedule brings a new set of observations, but the boundaries of the problem change as well. As spacecraft ages, its capabilities may degrade. As in-flight experience grows, capabilities may expand. As observing programs are completed, the needs and expectations of the science community may evolve. Changes such as these impact the rules by which a mission scheduled. In eight years on orbit, the Chandra X-Ray Observatory Mission Planning process has adapted to meet the challenge of maximizing day-to-day and mission lifetime science return, despite a consistently evolving set of scheduling constraints. The success of the planning team has been achieved, not through the use of complex algorithms and optimization routines, but through processes and home grown tools that help individuals make smart short term and long term Mission Planning decisions. This paper walks through the processes and tools used to plan and produce mission schedules for the Chandra X-Ray Observatory. Nominal planning and scheduling, target of opportunity response, and recovery from on-board autonomous safing actions are all addressed. Evolution of tools and processes, best practices, and lessons learned are highlighted along the way.

  2. Stellar Forensics with Striking Image from Chandra

    Science.gov (United States)

    2007-10-01

    A spectacular new image shows how complex a star's afterlife can be. By studying the details of this image made from a long observation by NASA's Chandra X-ray Observatory, astronomers can better understand how some stars die and disperse elements like oxygen into the next generation of stars and planets. At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. The image shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen, other elements such as neon and silicon that were forged in the star before it exploded. Hard X-ray Image of G292.0+1.8 Hard X-ray Image of G292.0+1.8 "We are finding that, just like snowflakes, each supernova remnant is complicated and beautiful in its own way," said Sangwook Park of Penn State who led the work, released in conjunction with the "8 Years of Chandra" symposium in Huntsville, Ala. The new, deep Chandra image - equaling nearly 6 days worth of observing time - shows an incredibly complex structure. Understanding the details of G292.0+1.8 is especially important because astronomers have considered it to be a "textbook" case of a supernova created by the death of a massive star. Chandra X-ray Image of G292.0+1.8 Chandra X-ray Image of G292.0+1.8 By mapping the distribution of X-rays in different energy bands, the Chandra image traces the distribution of chemical elements ejected in the supernova. The results imply that the explosion was not symmetrical. For example, blue (silicon and sulfur) and green (magnesium) are seen strongly in the upper right, while yellow and orange (oxygen) dominate the lower left. These elements light up at different temperatures, indicating that the temperature is higher in the upper right portion of G292.0+1.8. Slightly below and to the left of the center of G292.0+1.8 is a pulsar, a dense, rapidly rotating neutron star that remained behind after the original star

  3. Spectral Analysis of the Chandra Comet Survey

    CERN Document Server

    Bodewits, D; Torney, M; Dryer, M; Lisse, C M; Dennerl, K; Zurbuchen, T H; Wolk, S J; Tielens, A G G M; Hoekstra, R

    2007-01-01

    We present results of the analysis of cometary X-ray spectra with an extended version of our charge exchange emission model (Bodewits et al. 2006). We have applied this model to the sample of 8 comets thus far observed with the Chandra X-ray observatory and ACIS spectrometer in the 300-1000 eV range. The surveyed comets are C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), C/2000 WM1 (LINEAR), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), C/2001 Q4 (NEAT), 9P/2005 (Tempel 1) and 73P/2006-B (Schwassmann-Wachmann 3) and the observations include a broad variety of comets, solar wind environments and observational conditions. The interaction model is based on state selective, velocity dependent charge exchange cross sections and is used to explore how cometary X-ray emission depend on cometary, observational and solar wind characteristics. It is further demonstrated that cometary X-ray spectra mainly reflect the state of the local solar wind. The current sample of Chandra observations was fit using the constrains of ...

  4. Chandra Data Reveal Rapidly Whirling Black Holes

    Science.gov (United States)

    2008-01-01

    A new study using results from NASA's Chandra X-ray Observatory provides one of the best pieces of evidence yet that many supermassive black holes are spinning extremely rapidly. The whirling of these giant black holes drives powerful jets that pump huge amounts of energy into their environment and affects galaxy growth. A team of scientists compared leading theories of jets produced by rotating supermassive black holes with Chandra data. A sampling of nine giant galaxies that exhibit large disturbances in their gaseous atmospheres showed that the central black holes in these galaxies must be spinning at near their maximum rates. People Who Read This Also Read... NASA’s Swift Satellite Catches First Supernova in The Act of Exploding Black Holes Have Simple Feeding Habits Jet Power and Black Hole Assortment Revealed in New Chandra Image Erratic Black Hole Regulates Itself "We think these monster black holes are spinning close to the limit set by Einstein's theory of relativity, which means that they can drag material around them at close to the speed of light," said Rodrigo Nemmen, a visiting graduate student at Penn State University, and lead author of a paper on the new results presented at American Astronomical Society in Austin, Texas. The research reinforces other, less direct methods previously used which have indicated that some stellar and supermassive black holes are spinning rapidly. According to Einstein's theory, a rapidly spinning black hole makes space itself rotate. This effect, coupled with gas spiraling toward the black hole, can produce a rotating, tightly wound vertical tower of magnetic field that flings a large fraction of the inflowing gas away from the vicinity of the black hole in an energetic, high-speed jet. Computer simulations by other authors have suggested that black holes may acquire their rapid spins when galaxies merge, and through the accretion of gas from their surroundings. "Extremely fast spin might be very common for large

  5. Exposure Time Calculator for Immersion Grating Infrared Spectrograph: IGRINS

    OpenAIRE

    Le, Huynh Anh N.; Pak, Soojong; Jaffe, Daniel T.; Kaplan, Kyle; Lee, Jae-Joon; Im, Myungshin; Seifahrt, Andreas

    2015-01-01

    We present an exposure-time calculator (ETC) for the Immersion Grating Infrared Spectrograph (IGRINS). The signal and noise values are calculated by taking into account the telluric background emission and absorption, the emission and transmission of the telescope and instrument optics, and the dark current and read noise of the infrared detector arrays. For the atmospheric transmission, we apply models based on the amount of precipitable water vapor along the line of sight to the target. The...

  6. Research of fiber Bragg grating geophone based on cantilever beam

    Science.gov (United States)

    Wang, Liang; Chen, Shao-hua; Tao, Guo; Lu, Gui-wu; Zhao, Kun

    2009-07-01

    Along with the development of seismic exploration, the demand of frequency, dynamic range, precision and resolution ration is increased. However, the traditional geophone has disadvantages of narrower bandwidth, lower dynamic range and resolution, and cannot meet the new needs of seismic exploration. Geophone technology is a choke point, which constrains the development of petroleum prospecting in recent years. Fiber Bragg Grating seism demodulation technology is the newest kind of seism demodulation technology. The sensing probe of the Fiber Bragg Grating geophone is made up of Fiber Bragg Gating. The information which it collects is embodied by wavelength. The modulation-demodulation is accomplished by Fiber Bragg Gating geophone directly. In this paper, we design different size Fiber Bragg Grating geophones based on the transmission properties of Fiber Bragg Grating and cantilever beam method. Beryllium bronze and stainless steel are chosen as the elastic beam and shell materials, respectively. The parameters such as response function and sensitivity are given theoretically. In addition, we have simulated the transmission characteristics of Fiber Bragg Grating geophone by virtue of finite element analysis. The influences of wavelength, mass block, fiber length on the characteristics of geophones are discussed in detail, and finally the appropriate structural parameters are presented.

  7. Grating Spectroscopes and How to Use Them

    CERN Document Server

    Harrison, Ken M

    2012-01-01

    Transmission grating spectroscopes look like simple filters and are designed to screw into place on the eyepiece tube of a telescope for visual use, or into a camera adapter for digicam or CCD imaging. They are relatively inexpensive and by far the easiest type of astronomical spectroscope to use, and so are the starting point for most beginners. Using the most popular commercially made filter gratings - from Rainbow Optics in the United States to Star Analyser in the United Kingdon - as examples, the book provides all the information needed to set up and use the grating to obtain stellar spectra. It also presents methods of analyzing the results. No heavy mathematics or formulas are involved, although a reasonable level of proficiency in using an astronomic telescope and, if relevant, imaging camera, is assumed. This book contains many practical hints and tips - something that is almost essential to success when starting out. It encourages new users to get quick results, and by following the worked examples,...

  8. Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State

    Science.gov (United States)

    Nowak, Michael A.; Hanke, Manfred; Trowbridge, Sarah N.; Markoff, Sera B.; Wilms, Joern; Pottschmidt, Katja; Coppi, Paolo; Maitra, Dipankar; Davis, Jhn E.; Tramper, Frank

    2009-01-01

    Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states". Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the "focused wind" from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary s focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c2. All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum-dependent, none of the broad line fits allow for an inner disk radius that is > 40 GM/c(sup 2).

  9. Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State

    Science.gov (United States)

    Nowak, Michael A.; Hanke, Manfred; Trowbridge, Sarah N.; Markoff, Sera B.; Wilms, Jörn; Pottschmidt, Katja; Coppi, Paolo; Maitra, Dipankar; Davis, John E.; Tramper, Frank

    2011-02-01

    Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states." Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the "focused wind" from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary's focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c 2. All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus, whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum dependent, none of the broad line fits allow for an inner disk radius that is >40 GM/c 2.

  10. How To Cover NASA's Chandra X-ray Observatory

    Science.gov (United States)

    1999-07-01

    NASA's newest space telescope, the Chandra X-ray Observatory, is scheduled for launch not earlier than July 20, 1999, aboard Space Shuttle mission STS-93. The world's most powerful X-ray observatory, Chandra will join the Hubble Space Telescope and NASA's other great observatories in an unprecedented study of our universe. With its capability to "see" an otherwise invisible but violent, vibrant and ever-changing universe, Chandra will provide insights into the universe's structure and evolution. The following information is designed to assist news media representatives cover launch and activation of the Chandra X-ray Observatory. Covering from the Chandra Control Center NASA will establish a news center at the Chandra X-ray Observatory Operations Control Center in Cambridge, Mass., during the critical period of launch and early activation. The news center will be open from approximately two days prior to launch until the observatory is established in its operating orbit approximately 11 days after launch. The telephone numbers for the news center are: (617) 496-4454 (617) 496-4462 (617) 496-4484 The news center will be staffed around the clock during the Shuttle mission by media relations officers knowledgeable about the Chandra mission and its status. Media covering from the news center will be provided work space and have opportunities for face-to-face interviews with Chandra management, control team members and Chandra scientists. They will be able to participate in daily Chandra status briefings and have access to a special control room viewing area. Additionally, media covering from Cambridge will receive periodic status reports on Chandra and the STS-93 mission, and will be able to participate in interactive televised briefings on the STS-93 mission originating from other NASA centers. While advance accreditation is not required, media interested in covering Chandra from the Operations Control Center should contact Dave Drachlis by telephone at (256) 544

  11. Chandra Captures Flare From Brown Dwarf

    Science.gov (United States)

    2000-07-01

    The first flare ever seen from a brown dwarf, or failed star, was detected by NASA's Chandra X-ray Observatory. The bright X-ray flare has implications for understanding the explosive activity and origin of magnetic fields of extremely low mass stars. Chandra detected no X-rays at all from LP 944-20 for the first nine hours of a twelve hour observation, then the source flared dramatically before it faded away over the next two hours. "We were shocked," said Dr. Robert Rutledge of the California Institute of Technology in Pasadena, the lead author on the discovery paper to appear in the July 20 issue of Astrophysical Journal Letters. "We didn't expect to see flaring from such a lightweight object. This is really the 'mouse that roared.'" Chandra LP 944-20 X-ray Image Press Image and Caption The energy emitted in the brown dwarf flare was comparable to a small solar flare, and was a billion times greater than observed X-ray flares from Jupiter. The flaring energy is believed to come from a twisted magnetic field. "This is the strongest evidence yet that brown dwarfs and possibly young giant planets have magnetic fields, and that a large amount of energy can be released in a flare," said Dr. Eduardo Martin, also of Caltech and a member of the team. Professor Gibor Basri of the University of California, Berkeley, the principal investigator for this observation, speculated that the flare "could have its origin in the turbulent magnetized hot material beneath the surface of the brown dwarf. A sub-surface flare could heat the atmosphere, allowing currents to flow and give rise to the X-ray flare -- like a stroke of lightning." LP 944-20 is about 500 million years old and has a mass that is about 60 times that of Jupiter, or 6 percent that of the Sun. Its diameter is about one-tenth that of the Sun and it has a rotation period of less than five hours. Located in the constellation Fornax in the southern skies, LP 944-20 is one of the best studied brown dwarfs because it is

  12. Femtosecond direct-writing of low-loss fiber Bragg gratings using a continuous core-scanning technique.

    Science.gov (United States)

    Williams, Robert J; Krämer, Ria G; Nolte, Stefan; Withford, Michael J

    2013-06-01

    We report the inscription of low-loss fiber Bragg gratings using focused femtosecond (fs) pulses and a continuous core-scanning technique. This direct-write technique produces high-fidelity Type I-IR gratings that share the inherent advantages of other direct-write methods, such as the point-by-point (PbP) method, for which the grating period is a free parameter. However, here we demonstrate an order of magnitude improvement in scattering loss compared to PbP gratings, to a level comparable with that of phase-mask-based fs inscription. A first-order grating was inscribed in standard telecommunications fiber with -49 dB transmission at the Bragg wavelength and 0.1 dB broadband scattering loss. Potential application of these gratings to large-mode-area fibers and chirped grating fabrication are highlighted.

  13. Electromagnetically induced grating in a crystal of molecular magnets system

    Science.gov (United States)

    Liu, Jibing; Liu, Na; Shan, Chuanjia; Liu, Tangkun; Li, Hong; Zheng, Anshou; Xie, Xiao-Tao

    2016-07-01

    We investigate the response of the molecular system to the magnetic field modulation. Molecular magnets are subjected to a strong standing ac magnetic field and a weak probe magnetic field. The transmission and absorption of the weak probe magnetic field can be changed due to quantum coherence and the spatially modulating of the standing field. And a electromagnetically induced grating is formed in the crystal of molecular magnets via electromagnetically induced transparency (EIT). The diffraction efficiency of the grating can be adjusted efficiently by tuning the intensity of the standing wave field and the single photon detuning.

  14. Symmetry and resonant modes in platonic grating stacks

    CERN Document Server

    Haslinger, Stewart G; Movchan, Natasha V; McPhedran, Ross C

    2013-01-01

    We study the flexural wave modes existing in finite stacks of gratings containing rigid, zero-radius pins. We group the modes into even and odd classes, and derive dispersion equations for each. We study the recently discovered EDIT (elasto-dynamically inhibited transmission) phenomenon, and relate it to the occurrence of trapped waves of even and odd symmetries being simultaneously resonant. We show how the EDIT interaction may be steered over a wide range of frequencies and angles, using a strategy in which the single-grating reflectance is kept high, so enabling the quality factors of the even and odd resonances to be kept large.

  15. Chandra data archive operations: lessons learned

    Science.gov (United States)

    McCollough, Michael L.; Rots, Arnold H.; Winkelman, Sherry L.

    2006-06-01

    We present a discussion of the lessons learned from establishing and operating the Chandra Data Archive (CDA). We offer an overview of the archive, what preparations were done before launch, the transition to operations, actual operations, and some of the unexpected developments that had to be addressed in running the archive. From this experience we highlight some of the important issues that need to be addressed in the creation and running of an archive for a major project. Among these are the importance of data format standards; the integration of the archive with the rest of the mission; requirements throughout all phases of the mission; operational requirements; what to expect at launch; the user interfaces; how to anticipate new tasks; and overall importance of team management and organization.

  16. The BMW-Chandra Serendipitous Source Catalogue

    Science.gov (United States)

    Romano, P.; Campana, S.; Mignani, R. P.; Moretti, A.; Panzera, M. R.; Tagliaferri, G.

    We present the BMW-Chandra Source Catalogue drawn from all Chandra ACIS-I pointed observations with an exposure time in excess of 10 ks public as of March 2003 (136 observations). Using the wavelet detection algorithm developed by \\citep{Lazzatiea99} and \\citep{Campanaea99}, which can characterize point-like as well as extended sources, we identified 21325 sources which were visually inspected and verified. Among them, 16758 are not associated with the targets of the pointings and are considered certain; they have a 0.5-10 keV absorption corrected flux distribution median of ˜ 7 × 10-15 erg cm-2 s-1. The catalogue consists of source positions, count rates, extensions and relative errors in three energy bands (total, 0.5-7 keV; soft, 0.5-2 keV; and hard band, 2-7 keV), as well as the additional information drawn from the headers of the original files. We also extracted source counts in four additional energy bands, (0.5-1.0 keV, 1.0-2.0 keV, 2.0-4.0 keV and 4.0-7.0 keV). We compute the sky coverage in the soft and hard bands. The complete catalogue provides a sky coverage in the soft band (0.5-2 keV, S/N =3) of ˜ 8 deg2 at a limiting flux of ˜ 10-13 erg cm-2 s-1, and ˜ 2 deg2 at a limiting flux of ˜ 10-15 erg cm-2 s-1. http://www.merate.mi.astro.it/~xanadu/BMC/bmc_home.html

  17. Picosecond Holographic-Grating Spectroscopy

    NARCIS (Netherlands)

    Duppen, K.

    1987-01-01

    Interfering light waves produce an optical interference pattern in any medium that interacts with light. This modulation of some physical parameter of the system acts as a classical holographic grating for optical radiation. When such a grating is produced through interaction of pulsed light waves w

  18. Optical Fiber Grating based Sensors

    DEFF Research Database (Denmark)

    Michelsen, Susanne

    2003-01-01

    sampled gratings, was produced and investigated. It is based on the different temperature and strain response of these gratings. Both a transfer matrix method and an overlap calculation is performed to explain the sensor response. Another type of sensor is based on tuning and modulation of a laser...

  19. Stretchable diffraction gratings for spectrometry

    NARCIS (Netherlands)

    Simonov, A.N.; Grabarnik, S.; Vdovine, G.V

    2007-01-01

    We have investigated the possibility of using transparent stretchable diffraction gratings for spectrometric applications. The gratings were fabricated by replication of a triangular-groove master into a transparent viscoelastic. The sample length, and hence the spatial period, can be reversibly cha

  20. Silicon waveguide filter based on cladding modulated anti-symmetric long-period grating.

    Science.gov (United States)

    Liu, Qing; Gu, Zhonghua; Kee, Jack Sheng; Park, Mi Kyoung

    2014-12-01

    In this paper, we demonstrate an optical filter using cladding modulated anti-symmetric long-period grating in a two-mode silicon waveguide. The filter consists of a two-mode waveguide connected with an input and output single-mode waveguide through two linear tapers. The anti-symmetric grating is formed by placing two periodic arrays of silicon squares offset by half of a grating pitch along the two-mode waveguide. Light coupling occurs between two co-propagating modes at the coupling wavelength through the grating and results in a rejection band at the output. The grating pitch, coupling coefficient, transmission spectrum and 3-dB bandwidth of the grating are investigated with the coupled-mode theory. By using a cladding modulated grating, the grating coupling strength can be controlled over a wide range by the two-mode waveguide width or separation distance between the grating and waveguide. Band-rejection filters are experimentally demonstrated in 1-μm, 0.8-μm and 0.7-μm wide two-mode silicon waveguides and rejection bands with different bandwidths and maximal attenuation contrasts larger than 15 dB (~97% coupling efficiency) have been achieved.

  1. Process monitor gratings

    Science.gov (United States)

    Brunner, T. A.; Ausschnitt, C. P.

    2007-03-01

    Despite the increasing use of advanced imaging methods to pattern chip features, process windows continue to shrink with decreasing critical dimensions. Controlling the manufacturing process within these shrinking windows requires monitor structures designed to maximize both sensitivity and robustness. In particular, monitor structures must exhibit a large, measurable response to dose and focus changes over the entire range of the critical features process window. Any process variations present fundamental challenges to the effectiveness of OPC methods, since the shape compensation assumes a repeatable process. One particular process parameter which is under increasing scrutiny is focus blur, e.g. from finite laser bandwidth, which can cause such OPC instability, and thereby damage pattern fidelity. We introduce a new type of test target called the Process Monitor Grating (PMG) which is designed for extreme sensitivity to process variation. The PMG design principle is to use assist features to zero out higher diffraction orders. We show via simulation and experiment that such structures are indeed very sensitive to process variation. In addition, PMG targets have other desirable attributes such as mask manufacturability, robustness to pattern collapse, and compatibility with standard CD metrology methods such as scatterometry. PMG targets are applicable to the accurate determination of dose and focus deviations, and in combination with an isofocal grating target, allow the accurate determination of focus blur. The methods shown in this paper are broadly applicable to the characterization of process deviations using test wafers or to the control of product using kerf structures.

  2. An X-ray look at the Seyfert 1 Galaxy Mrk 590: XMM-Newton and Chandra reveal complexity in circumnuclear gas

    OpenAIRE

    Longinotti, A. L.; Bianchi, S.; Santos-Lleo, M.; Rodriguez-Pascual, P.; Guainazzi, M.; Cardaci, M.; Pollock, A.M.T.

    2007-01-01

    This paper reports on a partially simultaneous observation of the bright Seyfert 1 Galaxy Mrk590, performed by XMM-Newton and Chandra. The long exposure (~100 ks) allows to investigate with great detail the Fe K complex at 6-7 keV and the presence of soft X-ray spectral features. We have analysed XMM-Newton data from the European Photon Imaging Camera (EPIC) in the 0.5-12 keV band and from the Reflection Grating Spectrometer (RGS) in the 0.35-2.5 keV band, and data from the High Energy Transm...

  3. Six Years of Chandra Observations of Supernova Remnants

    OpenAIRE

    Weisskopf, Martin C.; Hughes, John P.

    2005-01-01

    We present a review of the first six years of Chandra X-ray Observatory observations of supernova remnants. From the official "first-light" observation of Cassiopeia A that revealed for the first time the compact remnant of the explosion, to the recent million-second spectrally-resolved observation that revealed new details of the stellar composition and dynamics of the original explosion, Chandra observations have provided new insights into the supernova phenomenon. We present an admittedly ...

  4. In Brief: Chandra Observatory marks 10 years in space

    Science.gov (United States)

    Showstack, Randy

    2009-08-01

    NASA's Chandra X-ray Observatory, originally envisioned as a 5-year mission, was deployed into an elliptical orbit around Earth 10 years ago, on 23 July 1999. The most powerful X-ray telescope yet, Chandra has provided a peak into the high-energy universe and has independently confirmed the existence of dark energy. Martin Weisskopf, Chandra project scientist at NASA's Marshall Space Flight Center, Huntsville, Ala., said discoveries made possible by the observatory “have made dramatic changes to our understanding of the universe and its constituents.” “The Great Observatories program—of which Chandra is a major part—shows how astronomers need as many tools as possible to tackle the big questions out there,” said Ed Weiler, associate administrator of NASA's Science Mission Directorate at NASA Headquarters in Washington. The Hubble Space Telescope, Compton Gamma Ray Observatory, and Spitzer Space Telescope are NASA's other Great Observatories. For more information, visit http://chandra.harvard.edu/ten/ and http://chandra.nasa.gov.

  5. Chandra Observations of QSO 2237+0305

    CERN Document Server

    Dai, X; Agol, E; Bautz, M W; Garmire, G P

    2003-01-01

    We present the observations of the gravitationally lensed system QSO 2237+0305 performed with the Chandra X-ray Observatory on 2000 Sept. 6, and on 2001 Dec. 8 for 30.3 ks and 9.5 ks, respectively. Imaging analysis resolves the four X-ray images of the Einstein Cross. A possible fifth image is detected; however, this detection less certain. Fits to the combined spectrum of all images of the Einstein Cross assuming a simple power law with Galactic and intervening absorption at the lensing galaxy yield a photon index of 1.90(+0.05,-0.05). For the first observation, this spectral model yields a 0.4-8.0 keV X-ray flux of 4.6e-13 erg cm-2 s-1 and a 0.4-8.0 keV lensed luminosity of 1.0e46 erg s-1. The source exhibits variability both over long and short time scales. The X-ray flux has dropped by 20% between the two observations, and the K-S test showed that image A is variable at the 97% confidence level within the first observation. Furthermore, a possible time-delay of 2.7(+0.5,-0.9) hours between images A and B ...

  6. Deep Chandra observations of Pictor A

    CERN Document Server

    Hardcastle, M J; Birkinshaw, M; Croston, J H; Goodger, J L; Marshall, H L; Perlman, E S; Siemiginowska, A; Stawarz, L; Worrall, D M

    2015-01-01

    We report on deep Chandra observations of the nearby broad-line radio galaxy Pictor A, which we combine with new Australia Telescope Compact Array (ATCA) observations. The new X-ray data have a factor 4 more exposure than observations previously presented and span a 15-year time baseline, allowing a detailed study of the spatial, temporal and spectral properties of the AGN, jet, hotspot and lobes. We present evidence for further time variation of the jet, though the flare that we reported in previous work remains the most significantly detected time-varying feature. We also confirm previous tentative evidence for a faint counterjet. Based on the radio through X-ray spectrum of the jet and its detailed spatial structure, and on the properties of the counterjet, we argue that inverse-Compton models can be conclusively rejected, and propose that the X-ray emission from the jet is synchrotron emission from particles accelerated in the boundary layer of a relativistic jet. For the first time, we find evidence that...

  7. Chandra observations of Cygnus OB2

    CERN Document Server

    Wright, Nicholas J; Drew, Janet E; Vink, Jorick S

    2011-01-01

    Cygnus OB2 is the nearest example of a massive star forming region, containing over 50 O-type stars and hundreds of B-type stars. We have analyzed two Chandra pointings in Cyg OB2, detecting ~1700 X-ray sources, of which ~1450 are thought to be members of the association. Optical and near-IR photometry has been obtained for ~90% of these sources from recent deep Galactic plane surveys. We have performed isochrone fits to the near-IR color-magnitude diagram, deriving ages of 3.5(+0.75,-1.0) and 5.25(+1.5,-1.0) Myrs for sources in the two fields, both with considerable spreads around the pre-MS isochrones. The presence of a second population in the region, somewhat older than the present-day O-type stars, has been suggested by other authors and fits with the ages derived here. The fraction of sources with inner circumstellar disks (as traced by the K-band excess) is found to be very low, but appropriate for a population of age ~5 Myrs. We measure the stellar mass functions and find a power-law slope of Gamma = ...

  8. Fiber Bragg gratings in the radiation environment: Change under the influence of radiolytic hydrogen

    Science.gov (United States)

    Butov, Oleg V.; Golant, Konstantin M.; Shevtsov, Igor'A.; Fedorov, Artem N.

    2015-08-01

    The change of the transmission spectra of fiber Bragg gratings written in the optical fibers, whose silica cores are doped with either germanium or nitrogen, is studied experimentally under the influence of gamma-radiation. The transmission spectra in the neighborhood of the resonance (Bragg) wavelengths were regularly recorded "in-situ" in the course of irradiation during 24 days. For this purpose, uncoated gratings were placed in a pool near the spent fuel rods of a nuclear reactor. The fibers with the gratings written in them were in immediate contact with water. The estimated total absorbed radiation dose of the fibers is approximately 5 MGy. Molecular hydrogen, which is produced by radiolysis of water and penetrates into the core of silica fiber, is found to interact with the defects of Ge-doped silica induced by gamma-radiation, thereby causing a strong impact on the parameters of the spectrum of the Bragg gratings. On the contrary, in the case of gratings inscribed in N-doped silica fibers, the hydrogen molecules interact with defects induced in the course of laser UV exposure during the grating writing only. The possible subsequent formation of additional defects in N-doped silica under the influence of gamma-radiation has no substantial impact on the transmission spectra of Bragg gratings, which remained stable. The obtained results suggest that a small amount of molecular hydrogen resided in the fiber core is the main source of radiation instability of Ge-doped fiber Bragg grating sensors in radiation environments. These hydrogen molecules can remain in the Bragg gratings, in particular, after the inscription process in the hydrogen-loaded fibers.

  9. Fiber Bragg gratings in the radiation environment: Change under the influence of radiolytic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Butov, Oleg V., E-mail: obutov@mail.ru; Golant, Konstantin M. [Kotel' nikov Institute of Radio-Engineering and Electronics of RAS, 11-7 Mokhovaya Str., Moscow 125009 (Russian Federation); Shevtsov, Igor' A.; Fedorov, Artem N. [Prolog LLC, PO Box 3007, Obninsk, the Kaluga Region 249033 (Russian Federation)

    2015-08-21

    The change of the transmission spectra of fiber Bragg gratings written in the optical fibers, whose silica cores are doped with either germanium or nitrogen, is studied experimentally under the influence of gamma-radiation. The transmission spectra in the neighborhood of the resonance (Bragg) wavelengths were regularly recorded “in-situ” in the course of irradiation during 24 days. For this purpose, uncoated gratings were placed in a pool near the spent fuel rods of a nuclear reactor. The fibers with the gratings written in them were in immediate contact with water. The estimated total absorbed radiation dose of the fibers is approximately 5 MGy. Molecular hydrogen, which is produced by radiolysis of water and penetrates into the core of silica fiber, is found to interact with the defects of Ge-doped silica induced by gamma-radiation, thereby causing a strong impact on the parameters of the spectrum of the Bragg gratings. On the contrary, in the case of gratings inscribed in N-doped silica fibers, the hydrogen molecules interact with defects induced in the course of laser UV exposure during the grating writing only. The possible subsequent formation of additional defects in N-doped silica under the influence of gamma-radiation has no substantial impact on the transmission spectra of Bragg gratings, which remained stable. The obtained results suggest that a small amount of molecular hydrogen resided in the fiber core is the main source of radiation instability of Ge-doped fiber Bragg grating sensors in radiation environments. These hydrogen molecules can remain in the Bragg gratings, in particular, after the inscription process in the hydrogen-loaded fibers.

  10. Extreme Silica Optical Fibre Gratings

    Directory of Open Access Journals (Sweden)

    Kevin Cook

    2008-10-01

    Full Text Available A regenerated optical fibre Bragg grating that survives temperature cycling up to 1,295°C is demonstrated. A model based on seeded crystallisation or amorphisation is proposed.

  11. A Full Year's Chandra Exposure on SDSS Quasars from the Chandra Multiwavelength Project

    CERN Document Server

    Green, Paul J; Richards, G T; Barkhouse, W A; Constantin, A; Haggard, D; Karovska, M; Kim, D -W; Kim, M; Vikhlinin, A; Mossman, A; Silverman, J D; Anderson, S F; Kashyap, V; Wilkes, B J; Tananbaum, H

    2008-01-01

    We study the spectral energy distributions and evolution of a large sample of optically selected quasars from the Sloan Digital Sky Survey (SDSS) that were observed in 323 Chandra images analyzed by the Chandra Multiwavelength Project (ChaMP). Our highest-confidence matched sample includes 1135 X-ray detected quasars in the redshift range 0.23 QSOs detected, we find no evidence for evolution out to z~5 for either the X-ray photon index Gamma or for the ratio of optical/UV to X-ray flux alpha_ox. About 10% of detected QSOs are obscured (Nh>1E22), but the fraction might reach ~1/3 if most non-detections are absorbed. We confirm a significant correlation between alpha_ox and optical luminosity, but it flattens or disappears for fainter AGN alone. Gamma hardens significantly both towards higher X-ray luminosity, and for relatively X-ray loud quasars. These trends may represent a relative increase in non-thermal X-ray emission, and our findings thereby strengthen analogies between Galactic black hole binaries and ...

  12. Chandra Spectroscopy of a Remarkable Neutron Star

    Science.gov (United States)

    Miller, Jon

    2013-09-01

    IGR J17062-6143 is one of only 5 sources that have displayed a super-expansion burst. This requires a special mode of continuous low-level accretion that allows material to accumulate on the stellar surface, without triggering smaller bursts. Swift spectroscopy of a super-expansion burst in IGR J17062-6143 revealed the only strong detections of atomic emission and absorption lines in a burst observed at CCD or gratings resolution. Whereas atomic features from the stellar surface have not been detected in other neutron stars, the accretion mode in IGR J17062-6143 may provide the right conditions. To search for lines from the surface, and to better understand the nature of low-level accretion, we request a 100 ksec HETGS observation of IGR J17062-6143.

  13. Optical fiber long-period grating with solgel coating for gas sensor

    Science.gov (United States)

    Gu, Zhengtian; Xu, Yanping; Gao, Kan

    2006-08-01

    The novel long-period fiber grating (LPFG) film sensor is composed of the long-period grating coated with solgel-derived sensitive films. The characteristics of the transmissivity of the LPFG film sensor are studied. By analyzing the relation among the sensitivity Sn, the thin film optical parameters, and the fiber grating parameters, the optimal design parameters of the LPFG film sensor are obtained. Data simulation shows that the resolution of the refractive index of this LPFG film sensor is predicted to be 10-8. Experimentally, a LPFG film sensor for detection of C2H5OH was fabricated, and a preliminary gas-sensing test was performed.

  14. Multiband processing of multimode light: combining 3D photonic lanterns with waveguide Bragg gratings

    OpenAIRE

    Spaleniak, Izabela; Gross, Simon; Jovanovic, Nemanja; Williams, Robert J.; Lawrence, Jon S.; Ireland, Michael J.; Withford, Michael J.

    2013-01-01

    The first demonstration of narrowband spectral filtering of multimode light on a 3D integrated photonic chip using photonic lanterns and waveguide Bragg gratings is reported. The photonic lanterns with multi-notch waveguide Bragg gratings were fabricated using the femtosecond direct-write technique in boro-aluminosilicate glass (Corning, Eagle 2000). Transmission dips of up to 5 dB were measured in both photonic lanterns and reference single-mode waveguides with 10.4-mm-long gratings. The res...

  15. Resonant Response in Mechanically Tunable Metasurface based on Crossed Metallic Gratings with Controllable Crossing Angle

    CERN Document Server

    Yachin, Vladimir V; Polevoy, Sergey Y; Tarapov, Sergey I

    2016-01-01

    We report on a resonant response in transmission spectra of a linearly polarized wave passing through the system of crossed gratings. Each grating consists of an array of parallel metallic strips located on the top of a dielectric substrate. It is revealed that the resonant position appears to be dependent on the angle of gratings crossing. It is found out that the resonant shift on the frequency scale appears as a result of increasing in the length of the resonating portion of the parallelogram periodic cell formed by the crossed metallic strips with decreasing crossing angle and the proposed design can be used in new types of planar metamaterials and filters.

  16. MEMS Bragg grating force sensor

    DEFF Research Database (Denmark)

    Reck, Kasper; Thomsen, Erik Vilain; Hansen, Ole

    2011-01-01

    We present modeling, design, fabrication and characterization of a new type of all-optical frequency modulated MEMS force sensor based on a mechanically amplified double clamped waveguide beam structure with integrated Bragg grating. The sensor is ideally suited for force measurements in harsh...... environments and for remote and distributed sensing and has a measured sensitivity of -14 nm/N, which is several times higher than what is obtained in conventional fiber Bragg grating force sensors. © 2011 Optical Society of America....

  17. All-optical switching of diffraction gratings infiltrated with dye-doped liquid crystals

    Science.gov (United States)

    Lucchetta, D. E.; Vita, F.; Simoni, F.

    2010-12-01

    We report the realization and the characterization of an all-optical switching device based on a transmission grating recorded in a polymeric substrate infiltrated with a methyl red-doped liquid crystal. The properties of this highly nonlinear mixture are exploited to modulate the diffraction of the grating by a pump beam when a static electric field is applied. The behavior of the device is in agreement with the existing model for methyl red-doped liquid crystals.

  18. Calculation of shear angles in holographic gratings recorded in bleached silver-halide emulsions

    OpenAIRE

    Beléndez Vázquez, Augusto; Pascual Villalobos, Inmaculada; Fuentes Rosillo, Rosa; Fimia Gil, Antonio

    1993-01-01

    Shearing phenomena in holographic gratings formed in bleached silver-halide emulsions due to chemical processing are evaluated. These effects are introduced because of the inability of emulsion-thickness changes to explain the anomalous detuning of the peak diffraction efficiency from the expected Bragg condition. Experimental results obtained with transmission and reflection gratings are presented and discussed considering shearing effects, and the values of the shear angles calculated from ...

  19. Coupled-mode analysis for single-helix chiral fiber gratings with small core-offset

    Institute of Scientific and Technical Information of China (English)

    Li Yang; Linlin Xue; Jue Su; Jingren Qian

    2011-01-01

    Using conventional coupled-mode theory,a set of coupled-mode equations are formulated for single-helix chiral fiber long-period gratings.A helical-core fiber is analyzed as an example.The analysis is simple in mathematical form and intuitive in physical concept.Based on the analysis,the polarization independence of mode coupling in special fiber gratings is revealed.The transmission characteristics of helical-core fibers are also simulated and discussed.

  20. Plasmonic V-groove waveguides with Bragg grating filters via nanoimprint lithography

    DEFF Research Database (Denmark)

    Smith, Cameron L. C.; Desiatov, Boris; Goykmann, Ilya;

    2012-01-01

    We demonstrate spectral filtering with state-of-the-art Bragg gratings in plasmonic V-groove waveguides fabricated by wafer scale processing based on nanoimprint lithography. Transmission spectra of the devices having 16 grating periods exhibit spectral rejection of the channel plasmon polaritons...... with effective refractive index values calculated by finite element simulations in COMSOL. The results represent advancement towards the implementation of plasmonic V-grooves with greater functional complexity and mass-production compatibility....

  1. The new neutron grating interferometer at the ANTARES beamline - Design, Principle, and Applications -

    OpenAIRE

    Reimann, Tommy; Mühlbauer, Sebastian; Horisberger, Michael; Böni, Peter; Schulz, Michael

    2016-01-01

    Neutron grating interferometry is an advanced method in neutron imaging that allows the simultaneous recording of the transmission, the differential phase and the dark-field image. Especially the latter has recently received high interest because of its unique contrast mechanism which marks ultra-small-angle neutron scattering within the sample. Hence, in neutron grating interferometry, an imaging contrast is generated by scattering of neutrons off micrometer-sized inhomogeneities. Although t...

  2. Pure Bending Characteristic of Tilted Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    Bo Liu; Yin-Ping Miao; Hai-Bin Zhou; Qi-Da Zhao

    2008-01-01

    a novel structure of the pure macro-bending sensor based on the tilted fiber Bragg grating (TFBG) is proposed. The TFBG located in the half circle with the different diameters is bent at a constant angle with respect to the tilted grating planes. With the variations of the curvature, the core-mode resonance is unchanged and the transmission power of cladding modes detected by the photodiodes varies linearly with curvature, while the ghost mode changes by the form of two-order polynomial. So we can use the transmission power of ghost mode or other cladding modes to detect bending curvature as shape sensor. From a practical point of view, the sensor proposed here is simple, low cost and easy to implement. Moreover, it is possible to make a temperature-insensitive shape sensor due to the same temperature characteristic between the core mode and the cladding modes.

  3. Time delay in double micro-ring resonator with grating

    Science.gov (United States)

    Li, Qiliang; Chen, Xin; Song, Junfeng; Bi, Meihua; Hu, Miao; Li, Shuqin

    2016-10-01

    In this paper, using the transfer matrix which is obtained by coupled mode theory, we have studied the transmission and time delay characteristics of the micro-ring resonator with the grating. We find that fast- and slow-light can occur in double ring resonator which contains the grating. We also study the effect of coupling coefficient on transmission characteristics. The results reveal that the increase of the coupling coefficient can lead to the change of the time delay at various ports at the resonant point. Thus by adjusting the frequency of the incident light and selecting the device with different coupling coefficient, we can realize the output of the fast and slow light.

  4. Bragg gratings inscription in step-index PMMA optical fiber by femtosecond laser pulses at 400 nm

    Science.gov (United States)

    Hu, X.; Kinet, D.; Chah, K.; Mégret, P.; Caucheteur, C.

    2016-05-01

    In this paper, we report photo-inscription of uniform Bragg gratings in trans-4-stilbenemethanol-doped photosensitive step-index polymer optical fiber. Gratings were produced at ~1575 nm by the phase mask technique with a femtosecond laser emitting at 400 nm with different average optical powers (8 mW, 13 mW and 20 mW). The grating growth dynamics in transmission were monitored during the manufacturing process, showing that the grating grows faster with higher power. Using 20 mW laser beam power, the reflectivity reaches 94 % (8 dB transmission loss) in 70 seconds. Finally, the gratings were characterized in temperature in the range 20 - 45 °C. The thermal sensitivity has been computed equal to - 86.6 pm/°C.

  5. High-Resolution {\\it Chandra} Spectroscopy of tau Scorpii A Narrow-Line X-ray Spectrum From a Hot Star

    CERN Document Server

    Cohen, D H; MacFarlane, J J; Miller, N A; Cassinelli, J P; Owocki, S P; Liedahl, D A; Cohen, David H.; Messi\\`{e}res, Genevi\\`{e}ve E. de; Farlane, Joseph J. Mac; Miller, Nathan A.; Cassinelli, Joseph P.; Owocki, Stanley P.; Liedahl, Duane A.

    2003-01-01

    Long known to be an unusual early-type star by virtue of its hard and strong X-ray emission, tau Scorpii poses a severe challenge to the standard picture of O star wind-shock X-ray emission. The Chandra HETGS spectrum now provides significant direct evidence that this B0.2 star does not fit this standard wind-shock framework. The many emission lines detected with the Chandra gratings are significantly narrower than what would be expected from a star with the known wind properties of tau Sco, although they are broader than the corresponding lines seen in late-type coronal sources. While line ratios are consistent with the hot plasma on this star being within a few stellar radii of the photosphere, from at least one He-like complex there is evidence that the X-ray emitting plasma is located more than a stellar radius above the photosphere. The Chandra spectrum of tau Sco is harder and more variable than those of other hot stars, with the exception of the young magnetized O star theta Ori C. We discuss these new...

  6. Optimization design of flat-band long-period grating

    Institute of Scientific and Technical Information of China (English)

    Yumin Liu(刘玉敏); Zhongyuan Yu(俞重远); Jianzhong Zhang(张建忠); Bojun Yang(杨伯君); Xiaoguang Zhang(张晓光)

    2004-01-01

    We present a method to optimize the flat-band long-period fiber Bragg grating (FBG) in this letter. The method is based on the particle swarm optimization method and the matrix transmission method. The optimized refractive modulation profile does not introduce so many phase shifts and is easier to fabricate compared with that of layer-peeling method which introduces lots of π phase shift at each zero point of apodization profile in designing for the same problem.

  7. Photonic scanning receiver using an electrically tuned fiber Bragg grating.

    Science.gov (United States)

    Rugeland, P; Yu, Z; Sterner, C; Tarasenko, O; Tengstrand, G; Margulis, W

    2009-12-15

    A 5-cm-long electrically tuned fiber Bragg grating is used to filter a microwave signal on an optical carrier at 1.55 mum. A chirped distributed-feedback structure is employed, with a transmission bandwidth of 54 MHz and relative optical carrier rejection of >30 dB for rf frequencies >2 GHz. The rapid monotonic sweep of the Bragg wavelength is translated into a fast-frequency sweep for rf analysis. PMID:20016616

  8. Deep Chandra observations of Pictor A

    Science.gov (United States)

    Hardcastle, M. J.; Lenc, E.; Birkinshaw, M.; Croston, J. H.; Goodger, J. L.; Marshall, H. L.; Perlman, E. S.; Siemiginowska, A.; Stawarz, Ł.; Worrall, D. M.

    2016-02-01

    We report on deep Chandra observations of the nearby broad-line radio galaxy Pictor A, which we combine with new Australia Telescope Compact Array (ATCA) observations. The new X-ray data have a factor of 4 more exposure than observations previously presented and span a 15 yr time baseline, allowing a detailed study of the spatial, temporal and spectral properties of the AGN, jet, hotspot and lobes. We present evidence for further time variation of the jet, though the flare that we reported in previous work remains the most significantly detected time-varying feature. We also confirm previous tentative evidence for a faint counterjet. Based on the radio through X-ray spectrum of the jet and its detailed spatial structure, and on the properties of the counterjet, we argue that inverse-Compton models can be conclusively rejected, and propose that the X-ray emission from the jet is synchrotron emission from particles accelerated in the boundary layer of a relativistic jet. For the first time, we find evidence that the bright western hotspot is also time-varying in X-rays, and we connect this to the small-scale structure in the hotspot seen in high-resolution radio observations. The new data allow us to confirm that the spectrum of the lobes is in good agreement with the predictions of an inverse-Compton model and we show that the data favour models in which the filaments seen in the radio images are predominantly the result of spatial variation of magnetic fields in the presence of a relatively uniform electron distribution.

  9. Writing Bragg Gratings in Multicore Fibers.

    Science.gov (United States)

    Lindley, Emma Y; Min, Seong-Sik; Leon-Saval, Sergio G; Cvetojevic, Nick; Lawrence, Jon; Ellis, Simon C; Bland-Hawthorn, Joss

    2016-01-01

    Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers. PMID:27167576

  10. Volume phase holographic gratings for the Subaru Prime Focus Spectrograph: performance measurements of the prototype grating set

    Science.gov (United States)

    Barkhouser, Robert H.; Arns, James; Gunn, James E.

    2014-08-01

    The Prime Focus Spectrograph (PFS) is a major instrument under development for the 8.2 m Subaru telescope on Mauna Kea. Four identical, fixed spectrograph modules are located in a room above one Nasmyth focus. A 55 m fiber optic cable feeds light into the spectrographs from a robotic fiber positioner mounted at the telescope prime focus, behind the wide field corrector developed for Hyper Suprime-Cam. The positioner contains 2400 fibers and covers a 1.3 degree hexagonal field of view. Each spectrograph module will be capable of simultaneously acquiring 600 spectra. The spectrograph optical design consists of a Schmidt collimator, two dichroic beamsplitters to separate the light into three channels, and for each channel a volume phase holographic (VPH) grating and a dual- corrector, modified Schmidt reimaging camera. This design provides a 275 mm collimated beam diameter, wide simultaneous wavelength coverage from 380 nm to 1.26 µm, and good imaging performance at the fast f/1.1 focal ratio required from the cameras to avoid oversampling the fibers. The three channels are designated as the blue, red, and near-infrared (NIR), and cover the bandpasses 380-650 nm (blue), 630-970 nm (red), and 0.94-1.26 µm (NIR). A mosaic of two Hamamatsu 2k×4k, 15 µm pixel CCDs records the spectra in the blue and red channels, while the NIR channel employs a 4k×4k, substrate-removed HAWAII-4RG array from Teledyne, with 15 µm pixels and a 1.7 µm wavelength cutoff. VPH gratings have become the dispersing element of choice for moderate-resolution astronomical spectro- graphs due their potential for very high diffraction efficiency, low scattered light, and the more compact instru- ment designs offered by transmissive dispersers. High quality VPH gratings are now routinely being produced in the sizes required for instruments on large telescopes. These factors made VPH gratings an obvious choice for PFS. In order to reduce risk to the project, as well as fully exploit the performance

  11. Theoretical analysis of novel fiber grating pair

    Science.gov (United States)

    Wang, Liao; Jia, Hongzhi; Fang, Liang; You, Bei

    2016-06-01

    A novel fiber grating pair that consists of a conventional long-period fiber grating and a fiber Bragg cladding grating (FBCG) is proposed. The FBCG is a new type of fiber grating in which refractive index modulation is formed in the cladding. Through the coupled-mode theory, we accurately calculate the coupling coefficients between modes supported in the fibers. And some other mode coupling features in the fiber cladding gratings are analyzed in detail. The calculation of the modes involved in this paper is based on a model of three-layer step-index fiber geometry. Then, we have investigated the sensitivity characteristics for variation of the modulation strengths of the fiber Bragg cladding gratings' resonance peaks and the long-period cladding gratings' (LPCGs) dual resonant peaks. Finally, the modulation strength sensitivity of the grating pair's three resonant peaks is demonstrated, and the results indicate that these grating pairs may find potential applications in optical fiber sensing.

  12. 75 FR 7471 - Chandra Coffee and Rabun Boatworks, Complainants v. Georgia Power Company, Respondent; Notice of...

    Science.gov (United States)

    2010-02-19

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Chandra Coffee and Rabun Boatworks, Complainants v. Georgia Power Company... January 8, 2010, Chandra Coffee and Rabun Boatworks (Complainants) filed with the Federal...

  13. Innovations in the Analysis of Chandra-ACIS Observations

    CERN Document Server

    Broos, Patrick S; Feigelson, Eric D; Getman, Konstantin V; Bauer, Franz E; Garmire, Gordon P

    2010-01-01

    As members of the instrument team for the Advanced CCD Imaging Spectrometer (ACIS) on NASA's Chandra X-ray Observatory and as Chandra General Observers, we have developed a wide variety of data analysis methods that we believe are useful to the Chandra community, and have constructed a significant body of publicly-available software (the ACIS Extract package) addressing important ACIS data and science analysis tasks. This paper seeks to describe these data analysis methods for two purposes: to document the data analysis work performed in our own science projects, and to help other ACIS observers judge whether these methods may be useful in their own projects (regardless of what tools and procedures they choose to implement those methods). The ACIS data analysis recommendations we offer here address much of the workflow in a typical ACIS project, including data preparation, point source detection via both wavelet decomposition and image reconstruction, masking point sources, identification of diffuse structure...

  14. The X-ray spectrum of delta Orionis observed by LETGS aboard Chandra

    CERN Document Server

    Raassen, A J J

    2013-01-01

    We analyze the high-resolution X-ray spectrum of the supergiant O-star delta Orionis (O9.5II) with line ratios of He-like ions and a thermal plasma model, and we examine its variability. The O-supergiant delta Ori was observed in the wavelength range 5-175 Angstrom by the X-ray detector HRC-S in combination with the grating LETG aboard Chandra. We studied the He-like ions in combination with the UV-radiation field to determine local plasma temperatures and to establish the distance of the X-ray emitting ions to the stellar surface. We measured individual lines by means of Gaussian profiles, folded through the response matrix, to obtain wavelengths, line fluxes, half widths at half maximum (HWHM) and line shifts to characterize the plasma. We consider multitemperature models in collisional ionization equilibrium (CIE) to determine temperatures, emission measures, and abundances. Analysis of the He-like triplets extended to N VI and C V implies ionization stratification with the hottest plasma to be found withi...

  15. Visible light metasurfaces based on gallium nitride high contrast gratings

    Science.gov (United States)

    Wang, Zhenhai; He, Shumin; Liu, Qifa; Wang, Wei

    2016-05-01

    We propose visible-light metasurfaces (VLMs) capable of serving as lens and beam deflecting element based on gallium nitride (GaN) high contrast gratings (HCGs). By precisely manipulating the wavefront of the transmitted light, we theoretically demonstrate an HCG focusing lens with transmissivity of 86.3%, and a VLM with beam deflection angle of 6.09° and transmissivity as high as 91.4%. The proposed all-dielectric metasurfaces are promising for GaN-based visible light-emitting diodes (LEDs), which would be robust and versatile for controlling the output light propagation and polarization, as well as enhancing the extraction efficiency of the LEDs.

  16. The Chandra X-Ray Observatory: Observations of Neutron Stars

    OpenAIRE

    Weisskopf, Martin C.

    2004-01-01

    We present here an overview of the status of the Chandra X-ray Observatory which has now been operating for five years. The Observatory is running smoothly, and the scientific return continues to be outstanding. We provide some details on the molecular contamination of the ACIS filters and its impact on observations. We review the observations with Chandra of the pulsar in the Crab Nebula and add some general comments as to the analysis of X-ray spectra. We conclude with comments about the fu...

  17. Lessons We Learned Designing and Building the Chandra Telescope

    Science.gov (United States)

    Arenberg, Jonathan; Matthews, Gary; Atkinson, C.; Cohen, L.; Golisano, C.; Havey, K.; Hefner, K.; Jones, C.; Kegley, J.; Knollenberg, P.; Lavoie, T.; Oliver, J.; Plucinsky, P.; Tananbaun, H.; Texter, S.; Weisskopf, M.

    2014-01-01

    2014 marks the crystal (15th) anniversary of the launch of the Chandra X-ray Observatory. This paper offers some of the major lessons learned by some of the key members of the Chandra Telescope team. We offer some of the lessons gleaned from our experiences developing, designing, building and testing the telescope and its subsystems, with 15 years of hindsight. Among the topics to be discussed are the early developmental tests, known as VETA-I and VETA-II, requirements derivation, the impact of late requirements and reflection on the conservatism in the design process.

  18. Chandra Observations of Eight Sources Discovered by INTEGRAL

    Science.gov (United States)

    Tomsick, John A.; Krivonos, Roman; Wang, Qinan; Bodaghee, Arash; Chaty, Sylvain; Rahoui, Farid; Rodriguez, Jerome; Fornasini, Francesca M.

    2016-01-01

    We report on 0.3-10 keV observations with the Chandra X-ray Observatory of eight hard X-ray sources discovered within 8° of the Galactic plane by the International Gamma-ray Astrophysics Laboratory satellite. The short (˜5 ks) Chandra observations of the IGR source fields have yielded very likely identifications of X-ray counterparts for three of the IGR sources: IGR J14091-6108, IGR J18088-2741, and IGR J18381-0924. The first two have very hard spectra in the Chandra band that can be described by a power law with photon indices of Γ = 0.6 ± 0.4 and -{0.7}-0.3+0.4, respectively (90% confidence errors are given), and both have a unique near-IR counterpart consistent with the Chandra position. IGR J14091-6108 also displays a strong iron line and a relatively low X-ray luminosity, and we argue that the most likely source type is a cataclysmic variable (CV), although we do not completely rule out the possibility of a high mass X-ray binary. IGR J18088-2741 has an optical counterpart with a previously measured 6.84 hr periodicity, which may be the binary orbital period. We also detect five cycles of a possible 800-950 s period in the Chandra light curve, which may be the compact object spin period. We suggest that IGR J18088-2741 is also most likely a CV. For IGR J18381-0924, the spectrum is intrinsically softer with {{Γ }}={1.5}-0.4+0.5, and it is moderately absorbed, NH = (4 ± 1) × 1022 cm-2. There are two near-IR sources consistent with the Chandra position, and they are both classified as galaxies, making it likely that IGR J18381-0924 is an active galactic nucleus. For the other five IGR sources, we provide lists of nearby Chandra sources, which may be used along with further observations to identify the correct counterparts, and we discuss the implications of the low inferred Chandra count rates for these five sources.

  19. Polarization Dependence Suppression of Optical Fiber Grating Sensor in a π-Shifted Sagnac Loop Interferometer

    Directory of Open Access Journals (Sweden)

    Jaebum Son

    2010-04-01

    Full Text Available In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port of a π-shifted Sagnac loop interferometer. General expressions for the transmittance and reflectance are derived for transmission-type, reflection-type, and partially reflecting/transmitting-type polarization-dependent optical devices. The compensation of polarization dependence through the counter propagation in the Sagnac loop interferometer is quantitatively measured for a commercial in-line polarizer and an acousto-optic long-period fiber grating sensor.

  20. High efficiency multilayer blazed gratings for EUV and soft X-rays: Recent developments

    Energy Technology Data Exchange (ETDEWEB)

    Voronov, Dmitriy; Ahn, Minseung; Anderson, Erik; Cambie, Rossana; Chang, Chih-Hao; Goray, Leonid; Gullikson, Eric; Heilmann, Ralf; Salmassi, Farhad; Schattenburg, Mark; Warwick, Tony; Yashchuk, Valeriy; Padmore, Howard

    2011-07-26

    Multilayer coated blazed gratings with high groove density are the best candidates for use in high resolution EUV and soft x-ray spectroscopy. Theoretical analysis shows that such a grating can be potentially optimized for high dispersion and spectral resolution in a desired high diffraction order without significant loss of diffraction efficiency. In order to realize this potential, the grating fabrication process should provide a perfect triangular groove profile and an extremely smooth surface of the blazed facets. Here we report on recent progress achieved at the Advanced Light Source (ALS) in fabrication of high quality multilayer coated blazed gratings. The blazed gratings were fabricated using scanning beam interference lithography followed by wet anisotropic etching of silicon. A 200 nm period grating coated with a Mo/Si multilayer composed with 30 bi-layers demonstrated an absolute efficiency of 37.6percent in the 3rd diffraction order at 13.6 nm wavelength. The groove profile of the grating was thoroughly characterized with atomic force microscopy before and after the multilayer deposition. The obtained metrology data were used for simulation of the grating efficiency with the vector electromagnetic PCGrate-6.1 code. The simulations showed that smoothing of the grating profile during the multilayer deposition is the main reason for efficiency losses compared to the theoretical maximum. Investigation of the grating with cross-sectional transmission electron microscopy revealed a complex evolution of the groove profile in the course of the multilayer deposition. Impact of the shadowing and smoothing processes on growth of the multilayer on the surface of the sawtooth substrate is discussed.

  1. High-efficiency multilayer blazed gratings for EUV and soft x-rays: recent developments

    Science.gov (United States)

    Voronov, Dmitriy L.; Ahn, Minseung; Anderson, Eric H.; Cambie, Rossana; Chang, Chih-Hao; Goray, Leonid I.; Gullikson, Eric M.; Heilmann, Ralf K.; Salmassi, Farhad; Schattenburg, Mark L.; Warwick, Tony; Yashchuk, Valeriy; Padmore, Howard A.

    2010-09-01

    Multilayer coated blazed gratings with high groove density are the best candidates for use in high resolution EUV and soft x-ray spectroscopy. Theoretical analysis shows that such a grating can be potentially optimized for high dispersion and spectral resolution in a desired high diffraction order without significant loss of diffraction efficiency. In order to realize this potential, the grating fabrication process should provide a perfect triangular groove profile and an extremely smooth surface of the blazed facets. Here we report on recent progress achieved at the Advanced Light Source (ALS) in fabrication of high quality multilayer coated blazed gratings. The blazed gratings were fabricated using scanning beam interference lithography followed by wet anisotropic etching of silicon. A 200 nm period grating coated with a Mo/Si multilayer composed with 30 bi-layers demonstrated an absolute efficiency of 37.6% in the 3rd diffraction order at 13.6 nm wavelength. The groove profile of the grating was thoroughly characterized with atomic force microscopy before and after the multilayer deposition. The obtained metrology data were used for simulation of the grating efficiency with the vector electromagnetic PCGrate-6.1 code. The simulations showed that smoothing of the grating profile during the multilayer deposition is the main reason for efficiency losses compared to the theoretical maximum. Investigation of the grating with cross-sectional transmission electron microscopy revealed a complex evolution of the groove profile in the course of the multilayer deposition. Impact of the shadowing and smoothing processes on growth of the multilayer on the surface of the sawtooth substrate is discussed.

  2. Nonperiodic metallic gratings transparent for broadband terahertz waves

    Science.gov (United States)

    Fan, Ren-Hao; Ren, Xiao-Ping; Peng, Ru-Wen; Huang, Xian-Rong; Wang, Mu

    Recently, we demonstrate both theoretically and experimentally that nonperiodic metallic gratings can become transparent for broadband terahertz waves. Quasiperiodic and disordered metallic gratings effectively weaken and even eliminate Wood's anomalies, which are the diffraction-related characters of periodic gratings. Consequently, both the transparence bandwidth and transmission efficiency are significantly increased due to the structural aperiodicity. Furthermore, we show that for a specific light source, for example, a line source, a corresponding nonperiodic transparent grating can be also designed. We expect that our findings can be applied for transparent conducting panels, perfect white-beam polarizers, antireflective conducting solar cells, and beyond. References: X. P. Ren, R. H. Fan, R. W. Peng, X. R. Huang, D. H. Xu, Y. Zhou, and Mu Wang, Physical Review B, 91, 045111 (2015); R. H. Fan, R. W. Peng, X. R. Huang, J. Li, Y. Liu, Q. Hu, Mu. Wang, and X. Zhang, Advanced Materials, 24, 1980 (2012); and X. R. Huang, R. W. Peng, and R. H. Fan. Physical Review Letters, 105, 243901 (2010).

  3. Chandra and XMM-Newton X-ray Observations of the Hyperactive T Tauri Star RY Tau

    CERN Document Server

    Skinner, Stephen L; Guedel, Manuel

    2016-01-01

    We present results of pointed X-ray observations of the accreting jet-driving T Tauri star RY Tau using Chandra and XMM-Newton. We obtained high-resolution grating spectra and excellent-quality CCD spectra and light curves with the objective of identifying the physical mechanisms underlying RY Tau's bright X-ray emission. Grating spectra reveal numerous emission lines spanning a broad range of temperature superimposed on a hot continuum. The X-ray emission measure distribution is dominated by very hot plasma at T_hot ~ 50 MK but higher temperatures were present during flares. A weaker cool plasma component is also present as revealed by low-temperature lines such as O VIII. X-ray light curves show complex variability consisting of short-duration (~hours) superhot flares accompanied by fluorescent Fe emission at 6.4 keV superimposed on a slowly-varying (~one day) component that may be tied to stellar rotation. The hot flaring component is undoubtedly of magnetic (e.g. coronal) origin. Soft and hard-band light ...

  4. Chandra and XMM-Newton X-Ray Observations of the Hyperactive T Tauri Star RY Tau

    Science.gov (United States)

    Skinner, Stephen L.; Audard, Marc; Güdel, Manuel

    2016-07-01

    We present results of pointed X-ray observations of the accreting jet-driving T Tauri star RY Tau using Chandra and XMM-Newton. We obtained high-resolution grating spectra and excellent-quality CCD spectra and light curves with the objective of identifying the physical mechanisms underlying RY Tau’s bright X-ray emission. Grating spectra reveal numerous emission lines spanning a broad range of temperature superimposed on a hot continuum. The X-ray emission measure distribution is dominated by very hot plasma at T hot ˜ 50 MK, but higher temperatures were present during flares. A weaker cool plasma component is also present as revealed by low-temperature lines such as O viii. X-ray light curves show complex variability consisting of short-duration (˜hours) superhot flares accompanied by fluorescent Fe emission at 6.4 keV superimposed on a slowly varying (˜one day) component that may be tied to stellar rotation. The hot flaring component is undoubtedly of magnetic (e.g., coronal) origin. Soft- and hard-band light curves undergo similar slow variability implying that at least some of the cool plasma shares a common magnetic origin with the hot plasma. Any contribution to the X-ray emission from cool shocked plasma is small compared to the dominant hot component but production of individual low-temperature lines such as O viii in an accretion shock is not ruled out.

  5. NASA Unveils First Images From Chandra X-Ray Observatory

    Science.gov (United States)

    1999-08-01

    Extraordinary first images from NASA's Chandra X-ray Observatory trace the aftermath of a gigantic stellar explosion in such stunning detail that scientists can see evidence of what may be a neutron star or black hole near the center. Another image shows a powerful X-ray jet blasting 200,000 light years into intergalactic space from a distant quasar. Released today, both images confirm that NASA's newest Great Observatory is in excellent health and its instruments and optics are performing up to expectations. Chandra, the world's largest and most sensitive X-ray telescope, is still in its orbital check-out and calibration phase. "When I saw the first image, I knew that the dream had been realized," said Dr. Martin Weisskopf, Chandra Project Scientist, NASA's Marshall Space Flight Center, Huntsville, AL. "This observatory is ready to take its place in the history of spectacular scientific achievements." "We were astounded by these images," said Harvey Tananbaum, Director of the Smithsonian Astrophysical Observatory's Chandra X- ray Center, Cambridge, MA. "We see the collision of the debris from the exploded star with the matter around it, we see shock waves rushing into interstellar space at millions of miles per hour, and, as a real bonus, we see for the first time a tantalizing bright point near the center of the remnant that could possibly be a collapsed star associated with the outburst." Chandra's PKS 0637-752 PKS 0637-752 After the telescope's sunshade door was opened last week, one of the first images taken was of the 320-year-old supernova remnant Cassiopeia A, which astronomers believe was produced by the explosion of a massive star. Material blasted into space from the explosion crashed into surrounding material at 10 million miles per hour. This collision caused violent shock waves, like massive sonic booms, creating a vast 50-million degree bubble of X-ray emitting gas. Heavy elements in the hot gas produce X-rays of specific energies. Chandra's ability

  6. Novel Bandwidth Sensor Based Fiber Grating

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, the basic principle and the design method of the bandwidth sensing of fiber grating are expounded, respectively. Several novel bandwidth sensor based fiber grating are analyzed and discussed.

  7. High Efficiency Low Scatter Echelle Grating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A high efficiency low scatter echelle grating will be developed using a novel technique of multiple diamond shaving cuts. The grating will have mirror surfaces on...

  8. Polymer optical fiber bragg grating sensors

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, Scott Wu; Andresen, Søren;

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings are reported. We have written fiber Bragg gratings for 1550 nm and 850 nm operations, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  9. Grating-Coupled Waveguide Cloaking

    Institute of Scientific and Technical Information of China (English)

    WANG Jia-Fu; QU Shao-Bo; XU Zhuo; MA Hua; WANG Cong-Min; XIA Song; WANG Xin-Hua; ZHOU Hang

    2012-01-01

    Based on the concept of a grating-coupled waveguide (GCW),a new strategy for realizing EM cloaking is presented.Using metallic grating,incident waves are firstly coupled into the effective waveguide and then decoupled into free space behind,enabling EM waves to pass around the obstacle.Phase compensation in the waveguide keeps the wave-front shape behind the obstacle unchanged.Circular,rectangular and triangular cloaks are presented to verify the robustness of the GCW cloaking.Electric field animations and radar cross section (RCS)comparisons convincingly demonstrate the cloaking effect.

  10. Embossed Bragg Gratings Based on Organically Modified Silane Waveguides in InP.

    Science.gov (United States)

    Liu, J; Lam, Y L; Chan, Y C; Zhou, Y; Ooi, B S; Tan, G; Yao, J

    2000-09-20

    Considering the large variety of applications for optical glass waveguide gratings, the effective production method of embossing for micropatterning, and the unique advantages of InP-based materials, we expect that hybridization of embossed optical glass waveguide gratings and InP substrates will inevitably lead to new applications in integrated optics. We present our preliminary results of research toward the development of solgel-derived glass waveguide gratings made by embossing on InP. Theoretically, the dependence of the stop-band FWHM and transmission contrast of the grating filter on the grating length, and the relationship between the Bragg grating's reflective wavelength and the dopant concentration in the solgel waveguide, are obtained. Experimentally, using organically modified silane, we solve the problem of mismatching of SiO(2) and InP, and successfully fabricate an embossed glass grating with a second-order Bragg reflection wavelength of 1580 nm and a FWHM of 0.7 nm fabricated upon a solgel waveguide on an InP substrate. PMID:18350088

  11. Highlights and Discoveries from the Chandra X-ray Observatory

    CERN Document Server

    Tananbaum, H; Tucker, W; Wilkes, B; Edmonds, P

    2014-01-01

    Within 40 years of the detection of the first extrasolar X-ray source in 1962,NASA's Chandra X-ray Observatory has achieved an increase in sensitivity of 10 orders of magnitude, comparable to the gain in going from naked-eye observations to the most powerful optical telescopes over the past 400 years. Chandra is unique in its capabilities for producing sub-arcsecond X-ray images with 100-200 eV energy resolution for energies in the range 0.08Chandra mission provides a long observing baseline with stable and well-calibrated instruments, enabling temporal studies over time-scales from milliseconds to years. In this report we present a selection of highlights that illustrate how observations using Chandra, sometimes alone, but often in conjunction with other telescopes, have deepened, and in some instances revolutionized, our understanding ...

  12. Chandra: Ten Years of Amazing Science with a Great Observatory

    Science.gov (United States)

    Weisskopf, Martin C.

    2009-01-01

    We review briefly review the history of the development of the Chandra X-Ray Observatory, highlighting certain details that many attendees of this Conference might not be aware of. We then present a selection of scientific highlights of the first 10 years of this remarkable and unique mission.

  13. The Chandra X-Ray Observatory: Progress Report and Highlights

    CERN Document Server

    Weisskopf, Martin C

    2012-01-01

    Over the past 13 years, the Chandra X-ray Observatory's ability to provide high resolution X-ray images and spectra have established it as one of the most versatile and powerful tools for astrophysical research in the 21st century. Chandra explores the hot, x-ray-emitting regions of the universe, observing sources with fluxes spanning more than 10 orders of magnitude, from the X-ray brightest, Sco X-1, to the faintest sources in the Chandra Deep Field South survey. Thanks to its continuing operational life, the Chandra mission now also provides a long observing baseline which, in and of itself, is opening new research opportunities. In addition, observations in the past few years have deepened our understanding of the co-evolution of supermassive black holes and galaxies, the details of black hole accretion, the nature of dark energy and dark matter, the details of supernovae and their progenitors, the interiors of neutron stars, the evolution of massive stars, and the high-energy environment of protoplanetar...

  14. Romanticism or Reality? An Exploration of Frances Mary Hendry's "Chandra."

    Science.gov (United States)

    Johnson, Jilaine

    This paper singles out a novel written for children about India, "Chandra" (1995) by Frances Mary Hendry, as a powerful and useful novel to present to today's 11 to 14 year old students. The paper contends that the novel allows students to explore and consider different value systems, challenges them to become aware of prejudice and the making of…

  15. Chandra Observations of Eight Sources Discovered by INTEGRAL

    CERN Document Server

    Tomsick, John A; Wang, Qinan; Bodaghee, Arash; Chaty, Sylvain; Rahoui, Farid; Rodriguez, Jerome; Fornasini, Francesca M

    2015-01-01

    We report on 0.3-10 keV observations with the Chandra X-ray Observatory of eight hard X-ray sources discovered within 8 degrees of the Galactic plane by the INTEGRAL satellite. The short (5 ks) Chandra observations of the IGR source fields have yielded very likely identifications of X-ray counterparts for three of the IGR sources: IGR J14091-6108, IGR J18088-2741, and IGR J18381-0924. The first two have very hard spectra in the Chandra band that can be described by a power-law with photon indices of Gamma = 0.6+/-0.4 and -0.7(+0.4)(-0.3), respectively (90% confidence errors are given), and both have a unique near-IR counterpart consistent with the Chandra position. IGR J14091-6108 also displays a strong iron line and a relatively low X-ray luminosity, and we argue that the most likely source type is a Cataclysmic Variable (CV), although we do not completely rule out the possibility of a High Mass X-ray Binary. IGR J18088-2741 has an optical counterpart with a previously measured 6.84 hr periodicity, which may...

  16. The Chandra X-Ray Observatory: Five Years of Operation

    OpenAIRE

    Weisskopf, Martin C.

    2005-01-01

    The Chandra X-ray Observatory is the X-ray component of NASA's Great Observatory Program and has been operating successfully for over five years. We present here brief overview of the technical performance and some of the remarkable discoveries.

  17. Cosmological constraints from Chandra observations of galaxy clusters.

    Science.gov (United States)

    Allen, Steven W

    2002-09-15

    Chandra observations of rich, relaxed galaxy clusters allow the properties of the X-ray gas and the total gravitating mass to be determined precisely. Here, we present results for a sample of the most X-ray luminous, dynamically relaxed clusters known. We show that the Chandra data and independent gravitational lensing studies provide consistent answers on the mass distributions in the clusters. The mass profiles exhibit a form in good agreement with the predictions from numerical simulations. Combining Chandra results on the X-ray gas mass fractions in the clusters with independent measurements of the Hubble constant and the mean baryonic matter density in the Universe, we obtain a tight constraint on the mean total matter density of the Universe, Omega(m), and an interesting constraint on the cosmological constant, Omega(Lambda). We also describe the 'virial relations' linking the masses, X-ray temperatures and luminosities of galaxy clusters. These relations provide a key step in linking the observed number density and spatial distribution of clusters to the predictions from cosmological models. The Chandra data confirm the presence of a systematic offset of ca. 40% between the normalization of the observed mass-temperature relation and the predictions from standard simulations. This finding leads to a significant revision of the best-fit value of sigma(8) inferred from the observed temperature and luminosity functions of clusters.

  18. The Chandra Observation of the IP TX Col

    OpenAIRE

    Schlegel, Eric M.; Salinas, Anandi

    2003-01-01

    We present a preliminary look at the serendipitous observation of the intermediate polar TX Col by Chandra. The 52 ksec observation is uninterrupted, providing an opportunity to disentangle the light curve and power spectra components. We illustrate the energy-dependence of the power spectrum.

  19. INNOVATIONS IN THE ANALYSIS OF CHANDRA-ACIS OBSERVATIONS

    International Nuclear Information System (INIS)

    As members of the instrument team for the Advanced CCD Imaging Spectrometer (ACIS) on NASA's Chandra X-ray Observatory and as Chandra General Observers, we have developed a wide variety of data analysis methods that we believe are useful to the Chandra community, and have constructed a significant body of publicly available software (the ACIS Extract package) addressing important ACIS data and science analysis tasks. This paper seeks to describe these data analysis methods for two purposes: to document the data analysis work performed in our own science projects and to help other ACIS observers judge whether these methods may be useful in their own projects (regardless of what tools and procedures they choose to implement those methods). The ACIS data analysis recommendations we offer here address much of the workflow in a typical ACIS project, including data preparation, point source detection via both wavelet decomposition and image reconstruction, masking point sources, identification of diffuse structures, event extraction for both point and diffuse sources, merging extractions from multiple observations, nonparametric broadband photometry, analysis of low-count spectra, and automation of these tasks. Many of the innovations presented here arise from several, often interwoven, complications that are found in many Chandra projects: large numbers of point sources (hundreds to several thousand), faint point sources, misaligned multiple observations of an astronomical field, point source crowding, and scientifically relevant diffuse emission.

  20. An Introduction to the Chandra Carina Complex Project

    CERN Document Server

    Townsley, Leisa K; Corcoran, Michael F; Feigelson, Eric D; Gagné, Marc; Montmerle, Thierry; Oey, M S; Smith, Nathan; Garmire, Gordon P; Getman, Konstantin V; Povich, Matthew S; Evans, Nancy Remage; Nazé, Yaël; Parkin, E R; Preibisch, Thomas; Wang, Junfeng; Wolk, Scott J; Chu, You-Hua; Cohen, David H; Gruendl, Robert A; Hamaguchi, Kenji; King, Robert R; Mac Low, Mordecai-Mark; McCaughrean, Mark J; Moffat, Anthony F J; Oskinova, L M; Pittard, Julian M; Stassun, Keivan G; ud-Doula, Asif; Walborn, Nolan R; Waldron, Wayne L; Churchwell, Ed; Nichols, J S; Owocki, Stanley P; Schulz, N S

    2011-01-01

    The Great Nebula in Carina provides an exceptional view into the violent massive star formation and feedback that typifies giant HII regions and starburst galaxies. We have mapped the Carina star-forming complex in X-rays, using archival Chandra data and a mosaic of 20 new 60ks pointings using the Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer, as a testbed for understanding recent and ongoing star formation and to probe Carina's regions of bright diffuse X-ray emission. This study has yielded a catalog of properties of >14,000 X-ray point sources; >9800 of them have multiwavelength counterparts. Using Chandra's unsurpassed X-ray spatial resolution, we have separated these point sources from the extensive, spatially-complex diffuse emission that pervades the region; X-ray properties of this diffuse emission suggest that it traces feedback from Carina's massive stars. In this introductory paper, we motivate the survey design, describe the Chandra observations, and present some simple results, pr...

  1. Efficient iterative technique for designing bragg gratings

    DEFF Research Database (Denmark)

    Plougmann, Nikolai; Kristensen, Martin

    2004-01-01

    We present a new iterative method for designing Bragg gratings based on the Levenberg-Marquardt method of minimizing a chi-squared merit function. It is effective for designing both weak and strong gratings and is particularly well suited for unchirped gratings....

  2. Gratings in passive and active optical waveguides

    DEFF Research Database (Denmark)

    Berendt, Martin Ole

    1999-01-01

    This research project has focused on gratings in optical waveguides. These gratings may be produced by UV photon imprinting in optical fibers or planar technology waveguides. The gratings are optical waveguide equivalents of bulk dielectric mirrors or diffraction grating. For a grating in a waveg......This research project has focused on gratings in optical waveguides. These gratings may be produced by UV photon imprinting in optical fibers or planar technology waveguides. The gratings are optical waveguide equivalents of bulk dielectric mirrors or diffraction grating. For a grating...... mode losses confirmed. An elaborated grating model, including the detailed shape of the index modulation, has been developed. This model improves the interpretation of grating growth dynamic, which is of value to both; analysis of the UV imprinting set-ups, and to the investigation of photosensitivity...... mechanisms in silica. An other important part of the project aimed at perfection of distributed feed back DFB fiber lasers. At the outset of this project, DFB fiber lasers had been demonstrated, now the DFB fiber lasers are in commercial production. One of the problems that had to be overcome was to secure...

  3. Hybrid grating reflectors: Origin of ultrabroad stopband

    DEFF Research Database (Denmark)

    Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug

    2016-01-01

    Hybrid grating (HG) reflectors with a high-refractive-index cap layer added onto a high contrast grating (HCG) provide a high reflectance close to 100% over a broader wavelength range than HCGs. The combination of a cap layer and a grating layer brings a strong Fabry-Perot (FP) resonance as well...

  4. Tunable Fiber Gratings and Their Applications

    Institute of Scientific and Technical Information of China (English)

    Z.; Fang; L.; Zhao; L.; Li; K.; Gao; Y.; Zhou; J.; Geng; R.; Qu; G.; Chen

    2003-01-01

    Some practical research topics on tunable fiber gratings in author's group are presented, including tuning speed, tuning range, tuning characteristics of gratings in HB fiber, and the tunability of the line-width. The applications of fiber gratings in communication and sensing are also discussed.

  5. Grating light reflection spectroelectrochemistry for detection of trace amounts of aromatic hydrocarbons in water

    Energy Technology Data Exchange (ETDEWEB)

    KELLY,MICHAEL J.; SWEATT,WILLIAM C.; KEMME,SHANALYN A.; KASUNIC,K.J.; BLAIR,DIANNA S.; ZAIDI,S.H.; MCNEIL,J.R.; BURGESS,L.W.; BRODSKY,A.M.; SMITH,S.A.

    2000-04-01

    Grating light reflection spectroscopy (GLRS) is an emerging technique for spectroscopic analysis and sensing. A transmission diffraction grating is placed in contact with the sample to be analyzed, and an incident light beam is directed onto the grating. At certain angles of incidence, some of the diffracted orders are transformed from traveling waves to evanescent waves. This occurs at a specific wavelength that is a function of the grating period and the complex index of refraction of the sample. The intensities of diffracted orders are also dependent on the sample's complex index of refraction. The authors describe the use of GLRS, in combination with electrochemical modulation of the grating, for the detection of trace amounts of aromatic hydrocarbons. The diffraction grating consisted of chromium lines on a fused silica substrate. The depth of the grating lines was 1 {micro}m, the grating period was 1 {micro}m, and the duty cycle was 50%. Since chromium was not suitable for electrochemical modulation of the analyte concentration, a 200 nm gold layer was deposited over the entire grating. This gold layer slightly degraded the transmission of the grating, but provided satisfactory optical transparency for the spectroelectrochemical experiments. The grating was configured as the working electrode in an electrochemical cell containing water plus trace amounts of the aromatic hydrocarbon analytes. The grating was then electrochemically modulated via cyclic voltammetry waveforms, and the normalized intensity of the zero order reflection was simultaneously measured. The authors discuss the lower limits of detection (LLD) for two analytes, 7-dimethylamino-1,2-benzophenoxazine (Meldola's Blue dye) and 2,4,6-trinitrotoluene (TNT), probed with an incident HeNe laser beam ({lambda} = 543.5 nm) at an incident angle of 52.5{degree}. The LLD for 7-dimethylamino-1,2-benzophenoxazine is approximately 50 parts per billion (ppb), while the LLD for TNT is approximately

  6. Gravitational Lens Helps Chandra Find Rare Type of Black Hole

    Science.gov (United States)

    2000-03-01

    A team of astronomers from England and France have reported strong evidence for the existence of a rare type of black hole, called a Type 2 quasar. Using NASA's Chandra X-ray Observatory, they have discovered a powerful source of X rays that appears to be a giant black hole that is hidden from optical telescopes by a veil of obscuring material. The latest discovery comes from a team led by British astronomers Andrew Fabian of the Institute of Astronomy in Cambridge and Ian Smail of the University of Durham. They used Chandra, NASA's Hubble Space Telescope, and the James Clerk Maxwell submillimeter telescope on Mauna Kea in Hawaii. By concentrating their search near two galaxy clusters, the astronomers exploited a gravitational lensing effect that can lead to a significant brightening of distant sources. Four new X-ray sources and seven submillimeter sources were discovered. The brightest X-ray source is concentrated in the center of a distant galaxy. The point-like source has a deficit of low energy X rays, consistent with absorption by a thick cloud of gas. The combination of powerful X-ray emission, absorption of low energy X rays, and the relatively normal optical appearance of the galaxy led the scientists to conclude that the source is a strong contender to be a genuine Type 2 quasar. Type 2 quasars have been predicted to exist by a popular model for quasars. Their discovery would confirm the so-called unified model for quasars, and help clarify the nature of the pervasive background glow at X-ray and submillimeter energies. Evidence for Type 2 quasars has been reported by other researchers, but the data were ambiguous. Now, the cloud of uncertainty is lifting, as scientists use Chandra to intensify the search. According to the unified model of quasars, a thick doughnut of gas and dust surrounds a central black hole. The source looks different, depending on whether it is observed through the doughnut, through the hole, or at an intermediate angle. In extreme

  7. A novel dual-wavelength fiber Bragg grating and its application in fiber ring laser

    Institute of Scientific and Technical Information of China (English)

    姜莉; 张东生; 董兴法; 开桂云; 董孝义

    2004-01-01

    A novel method for fabricating dual-wavelength fiber Bragg gratings (FBGs) by using one phase mask is developed. The method is based on a double-exposure technique. Our technique lends itself to writing gratings with controllable reflectivity and separation of two Bragg wavelengths. A grating with two equal transmission peaks of 20.25 dB is obtained by this method and the separation of the two Bragg wavelengths is about 0.8 nm. With the grating, we demonstrate a dual-wavelength erbium-doped fiber ring laser whose interval of the two peaks is 0.8 nm. The laser's peak powers can get 3.1 mW above and have a good stability.

  8. Polarization-independent light-dispersing optical device consisting of two diffraction gratings and a waveplate.

    Science.gov (United States)

    Amako, J; Fujii, E

    2014-06-10

    We report on a light-dispersing device consisting of two transmission gratings and a waveplate. The gratings separate two orthogonal polarization components of light incident at the Bragg angle. The waveplate, which is sandwiched between the gratings, functions as a polarization converter for oblique light incidence. With these optical parts suitably integrated, the resulting device efficiently diffracts unpolarized light with high spectral resolution. Using coupled-wave theories and Mueller matrix analysis, we constructed a device for a wavelength range of 680±50  nm with a 400 nm grating period. From the characterization of this optical device, we validated the proposed polarization-independent, light-dispersing concept. PMID:24921129

  9. Multiband processing of multimode light: combining 3D photonic lanterns with waveguide Bragg gratings

    CERN Document Server

    Spaleniak, Izabela; Jovanovic, Nemanja; Williams, Robert J; Lawrence, Jon S; Ireland, Michael J; Withford, Michael J

    2013-01-01

    The first demonstration of narrowband spectral filtering of multimode light on a 3D integrated photonic chip using photonic lanterns and waveguide Bragg gratings is reported. The photonic lanterns with multi-notch waveguide Bragg gratings were fabricated using the femtosecond direct-write technique in boro-aluminosilicate glass (Corning, Eagle 2000). Transmission dips of up to 5 dB were measured in both photonic lanterns and reference single-mode waveguides with 10.4-mm-long gratings. The result demonstrates efficient and symmetrical performance of each of the gratings in the photonic lantern. Such devices will be beneficial to space-division multiplexed communication systems as well as for units for astronomical instrumentation for suppression of the atmospheric telluric emission from OH lines.

  10. Design and development of long-period grating sensors for temperature monitoring

    Indian Academy of Sciences (India)

    Smita Chaubey; Purushottam Joshi; Manoj Kumar; Rajesh Arya; A K Nath; Sanjay Kher

    2007-10-01

    Long Period Gratings (LPGs) have been developed using carbon dioxide laser in a standard optical fibre. LPGs with a periodicity of 600 m and grating length of 24 mm have been inscribed on standard single mode fibre. Such gratings have been used in designing temperature sensors and temperature is monitored up to 80°C. The sensitivity of such type of sensor is 0·06 nm/° C where as for standard Fibre Bragg Grating (FBG) it is 0·011 nm/°C. The LPG performance is also evaluated after -ray irradiation for total dose of 5 KGy and has not shown any effect on transmission spectrum.

  11. Demonstrating and optimizing the dual dispersion and focusing functionality of grating-Fresnel lens

    Science.gov (United States)

    Zhou, Qian; Zhang, Jinchao; Ni, Kai; Pang, Jinchao; Tian, Rui

    2014-11-01

    As optical spectroscopy plays a vital role in many of modern science and engineering, there is a growing need for developing an inexpensive and miniature spectrometers. Many attempts have been tried to solve the issue. Grating-Fresnel is a hybrid device that fuses the functions of a grating and Fresnel lens into a single device. In this paper, we try to simulate reflection type and transmission type G-Fresnel device in ZAMAX. And with the aids of ZEMAX, we try to optimize the Fresnel lens, grating pattern. A better alignment for the CCD detector could also improve sensitivity of the system as well. In order to improve the resolution and sensitivity, the length between Fresnel lens and gratings will be optimized.

  12. Super-Period Gold Nanodisc Grating-Enabled Surface Plasmon Resonance Spectrometer Sensor.

    Science.gov (United States)

    Tian, Xueli; Guo, Hong; Bhatt, Ketan H; Zhao, Song Q; Wang, Yi; Guo, Junpeng

    2015-10-01

    We experimentally demonstrate a surface plasmon resonance spectrometer sensor by using an e-beam-patterned super-period gold nanodisc grating on a glass substrate. The super-period gold nanodisc grating has a small subwavelength period and a large diffraction grating period. The small subwavelength period enhances localized surface plasmon resonance, and the large diffraction grating period diffracts surface plasmon resonance radiation into different directions corresponding to different wavelengths. Surface plasmon resonance spectra are measured in the first order diffraction spatial profiles captured by a charge-coupled device (CCD) in addition to the traditional way of measurement using an external optical spectrometer in the zeroth order transmission. A surface plasmon resonance sensor for the bovine serum albumin protein nanolayer bonding is demonstrated by measuring the surface plasmon resonance shift in the first order diffraction spatial intensity profiles captured by the CCD.

  13. Tailoring absorption in metal gratings with resonant ultra-thin bridges

    CERN Document Server

    Vincenti, M A; Grande, M; D'Orazio, A; Scalora, M

    2013-01-01

    We present a theoretical analysis of the effects of short range surface plasmon polariton excitation on sub-wavelength bridges in metal gratings. We show that localized resonances in thin metal bridges placed within the slit of a free-standing silver grating dramatically modify transmission spectra and boost absorption regardless of the periodicity of the grating. Additionally, the interference of multiple localized resonances makes it possible to tailor the absorption properties of ultrathin gratings, regardless of the apertures' geometrical size. This tunable, narrow-band, enhanced-absorption mechanism triggered by resonant, short range surface plasmon polaritons may also enhance nonlinear optical processes like harmonic generation, in view of the large third-order susceptibility of metals.

  14. Reproducibility of splicer-based long-period fiber gratings for gain equalization

    Institute of Scientific and Technical Information of China (English)

    I. Cacciari; M. Brenci; R. Falclai; G. Nunzi Conti; S. Pelli; G. C. Righini

    2007-01-01

    We fabricated long-period fiber gratings (LPFGs) using electric arc discharges. We observed that the fiber becomes slightly tapered due to longitudinal tension during the arc: this effect depends on the arc current and time length. We experimentally investigated how these characteristics can influence grating' s performances, especially in view of employing the LPFG as gain equalizer for an erbium-doped optical amplifier. As expected, we found that the spectral response of the grating depends on the period A, the intensity of the perturbation, the grating length and the type of mode-coupling induced. Since this last parameter cannot be estimated directly from the transmission spectra, we propose a method to determine the modecoupling occurring in the device and to assess the index modulation induced by the electric arcs. This method combines both experimental and simulated data, and can be used to characterize LPFGs made-up by any method.

  15. First Terrestrial Soft X-ray Aurora Observations by Chandra

    Science.gov (United States)

    Bhardwaj, Anil; Elsner, Ronald F.; Gladstone, G. Randall; Waite, J. Hunter, Jr.; Cravens, Thomas E.; Ostgaard, Nikolai; Chang, Shen-Wu; Metzger, Albert E.; Majeed, Tariq

    2004-01-01

    Northern polar "auroral" regions of Earth was observed by High-Resolution Camera in imaging mode (T32C-I) aboard Chandra X-Ray Observatory (CXO) during mid December 2003 - mid April 2004. Ten CXO observations, each approximately 20 min duration, were made in a non-conventional method (due to CXO technical issues), such that Chandra was aimed at a fixed point in sky and the Earth's polar cusp was allowed to drift through the HRC-I field-of-view. The observations were performed when CXO was near apogee and timed during northern winter mostly near midnight (6 hr), except two observations which occurred around 1200 UT, so that northern polar region is entirely in dark and solar fluoresced x-ray contamination can be avoided. These observations were aimed at searching the Earth's soft x-ray aurora and to do a comparative study with Jupiter's x-ray aurora, where a pulsating x-ray hot-spot near the northern magnetic pole has been observed by Chandra that implies a particle source region near Jupiter's magnetopause, and entry of heavy solar wind ions due to high-latitude reconnection as a viable explanation for the soft x-ray emissions. The first Chandra soft (0.1-2 keV) x-ray observations of Earth's aurora show that it is highly variable (intense arc, multiple arcs, diffuse, at times almost absent). In at least one of the observations an isolated blob of emission is observed where we expect cusp to be: giving indication of solar wind charge-exchange signature in x-rays. We are comparing the Chandra x-ray observations with observations at other wavelengths and particle data from Earth-orbiting satellites and solar wind measurements from near-Earth ACE and SOH0 spacecraft. Preliminary results from these unique CXO-Earth observations will be presented and discussed.

  16. Asymmetric acoustic transmission in multiple frequency bands

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hong-xiang, E-mail: jsdxshx@ujs.edu.cn [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Yuan, Shou-qi, E-mail: Shouqiy@ujs.edu.cn [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Zhang, Shu-yi [Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-11-23

    We report both experimentally and numerically that the multi-band device of the asymmetric acoustic transmission is realized by placing two periodic gratings with different periods on both sides of two brass plates immersed in water. The asymmetric acoustic transmission can exist in four frequency bands below 1500 kHz, which arises from the interaction between various diffractions from the two gratings and Lamb modes in the brass plates immersed in water. The results indicate that the device has the advantages of multiple band, broader bandwidth, and simpler structure. Our finding should have great potential applications in ultrasonic devices.

  17. Compact Imaging Spectrometer Utilizing Immersed Gratings

    Energy Technology Data Exchange (ETDEWEB)

    Chrisp, Michael P. (Danville, CA); Lerner, Scott A. (Corvallis, OR); Kuzmenko, Paul J. (Livermore, CA); Bennett, Charles L. (Livermore, CA)

    2006-03-21

    A compact imaging spectrometer with an immersive diffraction grating that compensates optical distortions. The imaging spectrometer comprises an entrance slit for transmitting light, a system for receiving the light and directing the light, an immersion grating, and a detector array. The entrance slit, the system for receiving the light, the immersion grating, and the detector array are positioned wherein the entrance slit transmits light to the system for receiving the light and the system for receiving the light directs the light to the immersion grating and the immersion grating receives the light and directs the light through an optical element to the detector array.

  18. Calculation of thermal noise in grating reflectors

    CERN Document Server

    Heinert, Daniel; Friedrich, Daniel; Hild, Stefan; Kley, Ernst-Bernhard; Leavey, Sean; Martin, Iain W; Nawrodt, Ronny; Tünnermann, Andreas; Vyatchanin, Sergey P; Yamamoto, Kazuhiro

    2013-01-01

    Grating reflectors have been repeatedly discussed to improve the noise performance of metrological applications due to the reduction or absence of any coating material. So far, however, no quantitative estimate on the thermal noise of these reflective structures exists. In this work we present a theoretical calculation of a grating reflector's noise. We further apply it to a proposed 3rd generation gravitational wave detector. Depending on the grating geometry, the grating material and the temperature we obtain a thermal noise decrease by up to a factor of ten compared to conventional dielectric mirrors. Thus the use of grating reflectors can substantially improve the noise performance in metrological applications.

  19. Flexible nanofiber-coupled hybrid plasmonic Bragg grating.

    Science.gov (United States)

    Liu, Sheng; Zhou, Linjie; Xu, Jian; Wang, Xinyi; Chen, Jianping

    2016-05-01

    We report a hybrid plasmonic Bragg grating composed of a nanofiber coupled with orthogonally oriented metal strips. Numerical simulations are performed to study the transmission and reflection spectra of the grating. It shows that the TM polarization has much stronger Bragg reflection due to the excitation of hybrid plasmonic modes. The dependence of reflection peaks on several key device parameters is analyzed. Light propagation simulation further reveals that both fundamental and first-order TM modes are excited upon Bragg reflection, leading to two separate peaks in the spectrum. We implement the prototype device by attaching a nanofiber onto the surface of an array of sub-micrometer-wide metal strips. The main reflection peak is measured to have a 3-dB bandwidth of 15 nm and out-of-band rejection of more than 30 dB. The effects of nanofiber radius, alignment angle and coupling length on the device performance are also experimentally investigated. PMID:27137547

  20. Flat acoustic lens by acoustic grating with curled slits

    KAUST Repository

    Peng, Pai

    2014-10-01

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry-Perot resonance.

  1. High aspect ratio tungsten grating on ultrathin Si membranes for extreme UV lithography

    Science.gov (United States)

    Peng, Xinsheng; Ying, Yulong

    2016-09-01

    Extreme ultraviolet lithography is one of the modern lithography tools for high-volume manufacturing with 22 nm resolution and beyond. But critical challenges exist to the design and fabrication of large-scale and highly efficient diffraction transmission gratings, significantly reducing the feature sizes down to 22 nm and beyond. To achieve such a grating, the surface flatness, the line edge roughness, the transmission efficiency and aspect ratio should be improved significantly. Delachat et al (2015 Nanotechnology 26 108262) develop a full process to fabricate a tungsten diffraction grating on an ultrathin silicon membrane with higher aspect ratio up to 8.75 that met all the aforementioned requirements for extreme ultraviolet lithography. This process is fully compatible with standard industrial extreme ultraviolet lithography.

  2. Effective grating theory for resonance domain surface-relief diffraction gratings.

    Science.gov (United States)

    Golub, Michael A; Friesem, Asher A

    2005-06-01

    An effective grating model, which generalizes effective-medium theory to the case of resonance domain surface-relief gratings, is presented. In addition to the zero order, it takes into account the first diffraction order, which obeys the Bragg condition. Modeling the surface-relief grating as an effective grating with two diffraction orders provides closed-form analytical relationships between efficiency and grating parameters. The aspect ratio, the grating period, and the required incidence angle that would lead to high diffraction efficiencies are predicted for TE and TM polarization and verified by rigorous numerical calculations.

  3. Experimental observation of plasmons in a graphene monolayer resting on a two-dimensional subwavelength silicon grating

    DEFF Research Database (Denmark)

    Zhu, Xiaolong; Yan, Wei; Jepsen, Peter Uhd;

    2013-01-01

    as a template. Measured transmission spectra illustrate the excitation of graphene-plasmon polaritons, which is further supported by numerical simulations and theoretical prediction of plasmon-band diagrams. Our grating-assisted coupling to graphene-plasmon polaritons forms an important platform for graphene......We experimentally demonstrate graphene-plasmon polariton excitation in a continuous graphene monolayer resting on a two-dimensional subwavelength silicon grating. The subwavelength silicon grating is fabricated by a nanosphere lithography technique with a self-assembled nanosphere array......-based opto-electronics applications....

  4. Study of silicon strip waveguides with diffraction gratings and photonic crystals tuned to a wavelength of 1.5 µm

    Energy Technology Data Exchange (ETDEWEB)

    Barabanenkov, M. Yu., E-mail: barab@iptm.ru; Vyatkin, A. F.; Volkov, V. T.; Gruzintsev, A. N.; Il’in, A. I.; Trofimov, O. V. [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials (Russian Federation)

    2015-12-15

    Single-mode submicrometer-thick strip waveguides on silicon-on-insulator substrates, fabricated by silicon-planar-technology methods are considered. To solve the problem of 1.5-µm wavelength radiation input-output and its frequency filtering, strip diffraction gratings and two-dimensional photonic crystals are integrated into waveguides. The reflection and transmission spectra of gratings and photonic crystals are calculated. The waveguide-mode-attenuation coefficient for a polycrystalline silicon waveguide is experimentally estimated.

  5. Fiber Optic Fabry-Perot Current Sensor Integrated with Magnetic Fluid Using a Fiber Bragg Grating Demodulation

    OpenAIRE

    Ji Xia; Qi Wang; Xu Liu; Hong Luo

    2015-01-01

    An optical fiber current sensor based on Fabry-Perot interferometer using a fiber Bragg grating demodulation is proposed. Magnetic fluid is used as a sensitive medium in fiber optical Fabry-Perot (F-P) cavity for the optical characteristic of magnetic-controlled refractive index. A Fiber Bragg grating (FBG) is connected after the F-P interferometer which is used to reflect the optical power at the Bragg wavelength of the interference transmission spectrum. The corresponding reflective power o...

  6. A Technique for Characterization of Dimensional Changes in Slanted Holographic Gratings by Monitoring the Angular Selectivity Profile

    OpenAIRE

    Pandey, Nitesh; Naydenova, Izabela; Martin, Suzanne; Toal, Vincent

    2008-01-01

    A method has been developed for retrieving the complete angular selectivity profile of transmission holographic gratings in one step. The method is applied to study in real time the shrinkage and changes in the effective optical thickness of a slanted holographic grating recorded in an acrylamide-based photopolymer. It can form the basis of a holographic sensor of analytes that cause a thickness change in the holographic medium. It can also be useful for the study and optimization of holograp...

  7. Characterization of a Functional Hydrogel Layer on a Silicon-Based Grating Waveguide for a Biochemical Sensor

    OpenAIRE

    Hong, Yoo-Seung; Kim, Jongseong; Sung, Hyuk-Kee

    2016-01-01

    We numerically demonstrated the characteristics of a functional hydrogel layer on a silicon-based grating waveguide for a simple, cost-effective refractive index (RI) biochemical sensor. The RI of the functional hydrogel layer changes when a specific biochemical interaction occurs between the hydrogel-linked receptors and injected ligand molecules. The transmission spectral profile of the grating waveguide shifts depends on the amount of RI change caused by the functional layer. Our character...

  8. Study of silicon strip waveguides with diffraction gratings and photonic crystals tuned to a wavelength of 1.5 µm

    International Nuclear Information System (INIS)

    Single-mode submicrometer-thick strip waveguides on silicon-on-insulator substrates, fabricated by silicon-planar-technology methods are considered. To solve the problem of 1.5-µm wavelength radiation input-output and its frequency filtering, strip diffraction gratings and two-dimensional photonic crystals are integrated into waveguides. The reflection and transmission spectra of gratings and photonic crystals are calculated. The waveguide-mode-attenuation coefficient for a polycrystalline silicon waveguide is experimentally estimated

  9. Highlights and discoveries from the Chandra X-ray Observatory.

    Science.gov (United States)

    Tananbaum, H; Weisskopf, M C; Tucker, W; Wilkes, B; Edmonds, P

    2014-06-01

    Within 40 years of the detection of the first extra-solar x-ray source in 1962, NASA's Chandra X-ray Observatory has achieved an increase in sensitivity of 10 orders of magnitude, comparable to the gain in going from naked-eye observations to the most powerful optical telescopes over the past 400 years. Chandra is unique in its capabilities for producing sub-arcsecond x-ray images with 100-200 eV energy resolution for energies in the range 0.08 black holes; the growth of supermassive black holes and their role in the regulation of star formation and growth of galaxies; impacts of collisions, mergers, and feedback on growth and evolution of groups and clusters of galaxies; and properties of dark matter and dark energy. PMID:24913425

  10. Chandra and Swift Observations of Unidentified Fermi-LAT Objects

    Science.gov (United States)

    Donato, Davide; Cheung, T.; Gehrels, N.

    2010-03-01

    In the last year we targeted some of the unidentified Fermi-LAT objects (UFOs) at high Galactic latitude with Chandra and Swift in order to determine the basic properties (positions, fluxes, hardness ratios) of all X-ray sources within the Fermi-LAT localization circles. These satellites enable us to detect the X-ray conterparts with a flux limit that is at least an order of magnitude lower than achieved in extant RASS data and to further follow-up at other wavelengths, with the ultimate goal to reveal the nature of these enigmatic gamma-ray sources. Here we present the results obtained with 5 Chandra pointings of high Galactic latitude UFOs in the Fermi-LAT 3-months bright source list. The association of detected X-ray sources within the improved 11-months Fermi-LAT localization circles with available optical and radio observations is discussed.

  11. Resonant Effects of FPL and SPP for Light Transmitting through Subwavelength Metallic Gratings

    Institute of Scientific and Technical Information of China (English)

    马佑桥; 周骏; 何苗; P. Mormile

    2011-01-01

    A new model is proposed to explain the physical mechanism of the extraordinary transmission enhancement in subwavelength metallic grating. The extraordinary transmission enhancement is described by the co-operation of Fabry Perot-like (FPL) resonance and the surface plasmon polariton (SPP) resonance. The rigorous coupled-wave analysis (RCWA) and the finite difference time domain (FDTD) method are employed to illustrate the model by calcu- lating the transmission and the field distributions in the subwavelength metallic grating, respectively. And the numerical calculations show that transmission enhancement is achieved when the coupling resonance of the incident light, the surface plasmon polariton mode and the Fabry-Perot-Like mode is happened, which are in good agreement with the proposed model.

  12. Bragg waveguide grating as a 1d photonic band gap structure: COST 268 modelling task

    NARCIS (Netherlands)

    Ctyroky, J.; Helfert, S.; Pregla, R.; Bienstman, P.; Baets, R.; Ridder, de R.; Stoffer, R.; Klaasse, G.; Petracek, J.; Lalanne, P.; Hugonin, J.P.; Rue, de la R.M.

    2002-01-01

    Modal reflection, transmission and loss of deeply etched Bragg waveguide gratings were modelled by six European laboratories using independently developed two-dimensional (2D) numerical codes based on four different methods, with very good mutual agreement. It was found that (rather weak) material d

  13. The Chandra X-Ray Observatory (CXO): An Overview

    OpenAIRE

    Weisskopf, Martin C.

    1999-01-01

    Significant advances in science inevitably occur when the state of the art in instrumentation improves. NASA's newest Great Observatory, the Chandra X-Ray Observatory (CXO) -- formally known as the Advanced X-Ray Astrophysics Facility (AXAF) -- launched on July 23, 1999 and represents such an advance. The CXO is designed to study the x-ray emission from all categories of astronomical objects from normal stars to quasars.

  14. Fiber Bragg Grating Based Thermometry

    OpenAIRE

    Ahmed, Zeeshan; Filla, James; Guthrie, William; Quintavalle, John

    2016-01-01

    In recent years there has been considerable interest in developing photonic temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to resistance thermometry. In this study we examine the thermal response of FBGs over the temperature range of 233 K to 393 K. We demonstrate, in a hermetically sealed dry Argon environment, that FBG devices show a quadratic dependence on temperature with expanded uncertainties (k = 2) of ~500 mK. Our measurements indicate that the combined m...

  15. Diffraction gratings for lighting applications

    Science.gov (United States)

    Cornelissen, Hugo J.; de Boer, Dick K. G.; Tukker, Teus

    2013-09-01

    Sub-micron diffraction gratings have been used for two LED illumination applications. One is to create a transparent see through luminaire which can be used to illuminate and read a paper document or e-book. A second is a light sensor that can be used in a feedback loop to control a multicolor LED lamp. Optical design and experimental proof-of-principle are presented.

  16. 10+ more years of Chandra-XMM-Newton Synergy

    Science.gov (United States)

    Wilkes, B.

    2016-06-01

    In this current golden age of X-ray astronomy, the frontiers of the X-ray Universe are continually expanding in multiple, often unexpected, directions, due to the extraordinary success and longevity of both ESA's XMM-Newton and NASA's Chandra X-ray Observatory. These two ground-breaking, major observatories are supported by a number of smaller, more focused missions which feed into and expand the discovery space of X-ray astronomy even further. With the prospect of another decade of observing, now is an excellent time to take stock of how far we have come, and to look forward to the future with a view to maximizing the scientific legacy of both XMM-Newton and Chandra. This not only involves optimizing the contents of the archives and the impact of the science results, but also laying the ground-work for the next generation of X-ray telescopes, led by ESA's Athena mission in the late 2020s. I will summarize the synergy between XMM-Newton and Chandra, including complementary capabilities which facilitate coordinated observations and science programs, and overlapping capabilities which often provide the necessary confirmation (or not) of new, marginal and/or controversial results.

  17. Unveiling obscured accretion in the Chandra Deep Field South

    CERN Document Server

    Fiore, F; Santini, P; Puccetti, S; Brusa, M; Feruglio, C; Fontana, A; Giallongo, E; Comastri, A; Gruppioni, C; Pozzi, F; Zamorani, G; Vignali, C

    2007-01-01

    A large population of heavily obscured, Compton Thick AGNs is predicted by models of galaxy formation, models of Cosmic X-ray Background and by the ``relic'' super-massive black-hole mass function measured from local bulges. However, so far only a handful of Compton thick AGNs have been possibly detected using even the deepest Chandra and XMM surveys. Compton-thick AGNs can be recovered thanks to the reprocessing of the AGN UV emission in the infrared by selecting sources with AGN luminosity's in the mid-infrared and faint near-infrared and optical emission. To this purpose, we make use of deep HST, VLT, Spitzer and Chandra data on the Chandra Deep Field South to constrain the number of Compton thick AGN in this field. We show that sources with high 24micron to optical flux ratios and red colors form a distinct source population, and that their infrared luminosity is dominated by AGN emission. Analysis of the X-ray properties of these extreme sources shows that most of them are indeed likely to be highly obsc...

  18. Chandra Observation of Abell 2065: An Unequal Mass Merger?

    CERN Document Server

    Chatzikos, M; Sarazin, C L; Chatzikos, Marios; Sarazin, Craig L.

    2006-01-01

    We present an analysis of a 41 ks Chandra observation of the merging cluster Abell 2065 with the ACIS-I detector. Previous observations with ROSAT and ASCA provided evidence for an ongoing merger, but also suggested that there were two surviving cooling cores, which were associated with the two cD galaxies in the center of the cluster. The Chandra observation reveals only one X-ray surface brightness peak, which is associated with the more luminous, southern cD galaxy. The gas related with that peak is cool and displaced slightly from the position of the cD. The data suggest that this cool material has formed a cold front. On the other hand, in the higher spatial resolution Chandra image, the second feature to the north is not associated with the northern cD; rather, it appears to be a trail of gas behind the main cD. We argue that only one of the two cooling cores has survived the merger, although it is possible that the northern cD may not have possessed a cool core prior to the merger. We use the cool core...

  19. EIS Data on the Chandra Deep Field South Released

    Science.gov (United States)

    2001-03-01

    The purpose of this note is to announce that the ESO Imaging Survey programme has released a full set of optical/infrared data covering the socalled Chandra Deep Field South (CDF-S) rapidly becoming a favoured target for cosmological studies in the southern hemisphere. The field was originally selected for deep X-ray observations with Chandra and XMM. The former have already been completed producing the deepest high-resolution X-ray image ever taken with a total integration time of one million seconds. The data obtained by EIS include J and Ks infrared observations of an area of 0.1 square degree nearly matching the Chandra image down to JAB ~ 23.4 and KAB ~ 22.6 and UU'BVRI optical observations over 0.25 square degree, matching the XMM field of view, reaching 5 s limiting magnitudes of U'AB = 26.0, UAB = 25.7, BAB = 26.4, VAB = 25.4, RA B = 25.5 and IA B = 24.7 mag, as measured within a 2 ´ FWHM aperture.

  20. All-reflective femtosecond optical pump-probe setup for transient grating spectroscopy.

    Science.gov (United States)

    Cucini, R; Bencivenga, F; Masciovecchio, C

    2011-04-01

    We developed a pump-probe setup that can be used for free electron lasers based four-wave mixing experiments in the extreme ultraviolet/soft x-ray spectral range. The main feature of the proposed optical layout is the absence of transmission optics. Test measurements on liquid and solid samples carried out using the transient grating technique in both transmission and reflection geometry demonstrate the reliability of the setup. PMID:21478973

  1. Numerical Analysis of Thermal Dependence of the Spectral Response of Polymer Optical Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Hisham K. Hisham

    2016-06-01

    Full Text Available The thermal dependence of the spectral response (i.e. transmission, reflection and time delay (r responses of uniform polymer optical fiber (POF Bragg gratings has been investigated. In addition to the temperature dependence, the effects of grating strength (kLg and fiber index modulation (n have been investigated. Besides high capability of tunable wavelength due to the unique large and negative thermo-optic coefficient of POF, the spectral response for POF Bragg gratings show high stability and larger spectrum bandwidth with temperature variation compare with the silica optical fiber (SOF Bragg gratings, especially with the increase of the kLg value. It was found that by increasing kLg, the peak reflectance value increases and the bandwidth of the Bragg reflector become narrower. Also it’s shown by increasing the kLg value, r deceasing significantly and reach its minimum value at the designed wavelength (B. Furthermore, the r for POF Bragg gratings is less than that for SOF Bragg gratings at the same value of kLg. Also it’s found that the peak reflectivity value increases to around 60% when the n value increases from 110-4 to 510-4.

  2. Varied line-space gratings and applications

    International Nuclear Information System (INIS)

    This paper presents a straightforward analytical and numerical method for the design of a specific type of varied line-space grating system. The mathematical development will assume plane or nearly-plane spherical gratings which are illuminated by convergent light, which covers many interesting cases for synchrotron radiation. The gratings discussed will have straight grooves whose spacing varies across the principal plane of the grating. Focal relationships and formulae for the optical grating-pole-to-exist-slit distance and grating radius previously presented by other authors will be derived with a symbolic algebra system. It is intended to provide the optical designer with the tools necessary to design such a system properly. Finally, some possible advantages and disadvantages for application to synchrotron to synchrotron radiation beamlines will be discussed

  3. The spectral combination characteristic of grating and the bi-grating diffraction imaging effect

    Institute of Scientific and Technical Information of China (English)

    ZHANG WeiPing; HE XiaoRong

    2007-01-01

    This paper reports on a new property of grating,namely spectral combination,and on bi-grating diffraction imaging that is based on spectral combination.The spectral combination characteristic of a grating is the capability of combining multiple light beams of different wavelengths incident from specific angles into a single beam.The bi-grating diffraction imaging is the formation of the image of an object with two gratings: the first grating disperses the multi-color light beams from the object and the second combines the dispersed light beams to form the image.We gave the conditions necessary for obtaining the spectral combination.We also presented the equations that relate the two gratings' spatial frequencies,diffraction orders and positions necessary for obtaining the bi-grating diffraction imaging.

  4. Spectral evolution with incremental nanocoating of long period fiber gratings

    Science.gov (United States)

    Del Villar, Ignacio; Corres, Jesus M.; Achaerandio, Miguel; Arregui, Francisco J.; Matias, Ignacio R.

    2006-12-01

    The incremental deposition of a thin overlay on the cladding of a long-period fiber grating (LPFG) induces important resonance wavelength shifts in the transmission spectrum. The phenomenon is proved theoretically with a vectorial method based on hybrid modes and coupled mode theory, and experimentally with electrostatic self-assembly monolayer process. The phenomenon is repeated periodically for specific overlay thickness values with the particularity that the shape of the resonance wavelength shift depends on the thickness of the overlay. The main applications are the design of wide optical filters and multiparameter sensing devices.

  5. Synchrotron Radiation from Outer Space and the Chandra X-Ray Observatory

    OpenAIRE

    Weisskopf, Martin C.

    2006-01-01

    The universe provides numerous extremely interesting astrophysical sources of synchrotron X radiation. The Chandra X-ray Observatory and other X-ray missions provide powerful probes of these and other cosmic X-ray sources. Chandra is the X-ray component of NASA's Great Observatory Program which also includes the Hubble Space telescope, the Spitzer Infrared Telescope Facility, and the now defunct Compton Gamma-Ray Observatory. The Chandra X-Ray Observatory provides the best angular resolution ...

  6. Multilayer dielectric gratings for tiled-gratings compression of petawatt pulses.

    OpenAIRE

    Cotel, Arnaud

    2007-01-01

    Pulse compression diffraction gratings represent currently an important bottleneck for the development of energetic high-intensity Petawatt laser. Indeed, the laser-induced damage threshold of standard gold-coated gratings and the diffraction efficiency are limited. That's why we have developed a new generation of diffraction gratings: ! multilayer dielectric (MLD) gratings. Studies of MLD g! ratings applied to the Pico2000 laser project are the first part of my thesis work. On the other hand...

  7. Chandra Reviews Black Hole Musical: Epic But Off-Key

    Science.gov (United States)

    2006-10-01

    A gigantic sonic boom generated by a supermassive black hole has been found with NASA's Chandra X-ray Observatory, along with evidence for a cacophony of deep sound. This discovery was made by using data from the longest X-ray observation ever of M87, a nearby giant elliptical galaxy. M87 is centrally located in the Virgo cluster of galaxies and is known to harbor one of the Universe's most massive black holes. Scientists detected loops and rings in the hot, X-ray emitting gas that permeates the cluster and surrounds the galaxy. These loops provide evidence for periodic eruptions that occurred near the supermassive black hole, and that generate changes in pressure, or pressure waves, in the cluster gas that manifested themselves as sound. Chandra Low Energy X-ray Images of M87 Chandra Low Energy X-ray Images of M87 "We can tell that many deep and different sounds have been rumbling through this cluster for most of the lifetime of the Universe," said William Forman of the Harvard-Smithsonian Center for Astrophysics (CfA). The outbursts in M87, which happen every few million years, prevent the huge reservoir of gas in the cluster from cooling and forming many new stars. Without these outbursts and resultant heating, M87 would not be the elliptical galaxy it is today. "If this black hole wasn't making all of this noise, M87 could have been a completely different type of galaxy," said team member Paul Nulsen, also of the CfA, "possibly a huge spiral galaxy about 30 times brighter than the Milky Way." Chandra High Energy X-ray Image of M87 Chandra High Energy X-ray Image of M87 The outbursts result when material falls toward the black hole. While most of the matter is swallowed, some of it was violently ejected in jets. These jets are launched from regions close to the black hole (neither light nor sound can escape from the black hole itself) and push into the cluster's gas, generating cavities and sound which then propagate outwards. Chandra's M87 observations also

  8. Perfect crystallike gratings for cold neutrons

    International Nuclear Information System (INIS)

    We report on significant improvements of the performance of thick diffraction gratings for cold neutrons. The basis material for the production of holographic gratings by optical means is photosensitized deuterated poly(methyl methacrylate) (D-PMMA). The properties of these gratings now approach those of perfect monochromator crystals for neutrons of shorter wavelength: for cold neutrons with 1.0 nm wavelength the gratings exhibit a reflectivity in the percent range which makes them suitable for a wide range of applications in neutron optics

  9. Dynamic fiber Bragg grating sensing method

    Science.gov (United States)

    Ho, Siu Chun Michael; Ren, Liang; Li, Hongnan; Song, Gangbing

    2016-02-01

    The measurement of high frequency vibrations is important in many scientific and engineering problems. This paper presents a novel, cost effective method using fiber optic fiber Bragg gratings (FBGs) for the measurement of high frequency vibrations. The method uses wavelength matched FBG sensors, with the first sensor acting as a transmission filter and the second sensor acting as the sensing portion. Energy fluctuations in the reflection spectrum of the second FBG due to wavelength mismatch between the sensors are captured by a photodiode. An in-depth analysis of the optical circuit is provided to predict the behavior of the method as well as identify ways to optimize the method. Simple demonstrations of the method were performed with the FBG sensing system installed on a piezoelectric transducer and on a wind turbine blade. Vibrations were measured with sampling frequencies up to 1 MHz for demonstrative purposes. The sensing method can be multiplexed for use with multiple sensors, and with care, can be retrofitted to work with FBG sensors already installed on a structure.

  10. Nonlinear transmission properties in bacteriorhodopsin-embedded photonic crystal

    Science.gov (United States)

    Okada-Shudo, Yoshiko; Ishihara, Teruya

    2003-11-01

    Transmission spectra and photoinduced transmission change are observed in periodic waveguide which consist of a quartz grating substrate and a thin protein film of bacteriorhodopsin. We propose a scheme to achieve all optical switching using the photoinduced refractive index change of bacteriorhodopsin.

  11. Catching a Galactic Football: Chandra Examines Cygnus A

    Science.gov (United States)

    2000-11-01

    Using NASA's Chandra X-ray Observatory, astronomers have found a giant football-shaped cavity within X-ray emitting hot gas surrounding the galaxy Cygnus A. The cavity in the hot gas has been created by two powerful jets emitted from the central black hole region in the nucleus of Cygnus A. Hot gas is steadily being piled up around the cavity as it continuously expands, creating a bright rim of X-ray emission. The jets themselves terminate in radio and X-ray emitting "hot spots" some 300,000 light years from the center of the galaxy. These results are being presented to the High Energy Astrophysics Division of the American Astronomical Society meeting in Honolulu, HI, by Andrew S. Wilson, Andrew J. Young (University of Maryland) and Patrick L. Shopbell (California Institute of Technology). "This is a spectacular cavity, which is inflated by jets and completely surrounds the Cygnus A galaxy," said Dr. Wilson, who is Professor of Astronomy at the University of Maryland, College Park. "We are witnessing a battle between the gravity of the Cygnus A galaxy, which is trying to pull the hot gas inwards, and the pressure of material created by the jets, which is trying to push the hot gas outwards." Cygnus A has long been famous as the brightest radio source in the sky. It is the nearest powerful radio galaxy. The Chandra X-ray image, which was taken with the Advanced CCD Imaging Spectrometer (ACIS), shows the cavity surrounded by a vast sea of extremely hot gas. The elongated oval shape comes from the force of the outwardly moving jets as they push through the hot gas. Bright bands around the "equator of the football" are also visible, and this may be evidence of material swirling toward the central black hole. Cygnus A Illustration Illustration of Cygnus A Credit: CXC Without the jets, an X-ray image of Cygnus A, which is about 700 million light years from Earth, would appear as a more or less spherical region (about 2 million light years across) of hot gas slowly

  12. Interrogating a Fiber Bragg Grating Vibration Sensor by Narrow Line Width Light

    Institute of Scientific and Technical Information of China (English)

    Jun Chang; Dian-Heng Huo; Liang-Zhu Ma; Xiao-Hui Liu; Tong-Yu Liu; Chang Wang

    2008-01-01

    A method to interrogate fiber Bragg grating vibration sensor by narrow line width light is demonstrated. The interrogation scheme takes advantage of the intensity modulation of narrow spectral bandwidth light, such as distributed feedback laser, when a reflection or transmission spectrum curve of an fiber Bragg grating (FBG) moves due to the strain which is applied on the sensor. The sensor's response to accelerating frequency and amplitude is measured by experiment. The factors which have impacts on the sensitivity of the interrogation system are also discussed.

  13. Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

    Directory of Open Access Journals (Sweden)

    Rosane Falate

    2007-01-01

    Full Text Available We report the use of an optical fiber sensor to measure the soybean oil concentration in samples obtained from the mixture of pure biodiesel and commercial soybean oil. The operation of the device is based on the long-period grating sensitivity to the surrounding medium refractive index, which leads to measurable modifications in the grating transmission spectrum. The proposed analysis method results in errors in the oil concentration of 0.4% and 2.6% for pure biodiesel and commercial soybean oil, respectively. Techniques of total glycerol, dynamic viscosity, density, and hydrogen nuclear magnetic resonance spectroscopy were also employed to validate the proposed method.

  14. Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

    Energy Technology Data Exchange (ETDEWEB)

    Falate, Rosane [Universidade Estadual de Ponta Grossa, PR (Brazil). Dept. de Informatica; Nike, Karen; Costa Neto, Pedro Ramos da [Universidade Tecnologica Federal do Parana, Curitiba (Brazil). Dept. de Quimica; Cacao Junior, Eduardo; Muller, Marcia; Kalinowski, Hypolito Jose; Fabris, Jose Luis [Universidade Tecnologica Federal do Parana, Curitiba (Brazil). Dept. de Fisica]. E-mail: fabris@utfpr.edu.br

    2007-07-01

    We report the use of an optical fiber sensor to measure the soybean oil concentration in samples obtained from the mixture of pure biodiesel and commercial soybean oil. The operation of the device is based on the long-period grating sensitivity to the surrounding medium refractive index, which leads to measurable modifications in the grating transmission spectrum. The proposed analysis method results in errors in the oil concentration of 0.4% and 2.6% for pure biodiesel and commercial soybean oil, respectively. Techniques of total glycerol, dynamic viscosity, density, and hydrogen nuclear magnetic resonance spectroscopy were also employed to validate the proposed method. (author)

  15. Gamma radiation-induced blue shift of resonance peaks of Bragg gratings in pure silica fibres

    Science.gov (United States)

    Faustov, A. V.; Gusarov, A. I.; Mégret, P.; Wuilpart, M.; Kinet, D.; Zhukov, A. V.; Novikov, S. G.; Svetukhin, V. V.; Fotiadi, A. A.

    2016-02-01

    We report the first observation of a significant gamma radiation-induced blue shift of the reflection/transmission peak of fibre Bragg gratings inscribed into pure-silica core fibres via multiphoton absorption of femtosecond pulses. At a total dose of ~100 kGy, the shift is ~20 pm. The observed effect is attributable to the ionising radiation-induced decrease in the density of the silica glass when the rate of colour centre formation is slow. We present results of experimental measurements that provide the key parameters of the dynamics of the gratings for remote dosimetry and temperature sensing.

  16. High resolution on-chip optical filter array based on double subwavelength grating reflectors.

    Science.gov (United States)

    Horie, Yu; Arbabi, Amir; Han, Seunghoon; Faraon, Andrei

    2015-11-16

    An optical filter array consisting of vertical narrow-band Fabry-Pérot (FP) resonators formed by two highly reflective high contrast subwavelength grating mirrors is reported. The filters are designed to cover a wide range of operation wavelengths (Δλ/λ = 5%) just by changing the in-plane grating parameters while the device thickness is maintained constant. Operation in the telecom band with transmission efficiencies greater than 40% and quality factors greater than 1,000 are measured experimentally for filters fabricated on the same substrate. PMID:26698468

  17. Recording multiple holographic gratings in silver-doped photopolymer using peristrophic multiplexing

    Indian Academy of Sciences (India)

    V Pramitha; Rani Joseph; K Sreekumar; C Sudha Kartha

    2010-12-01

    Plane-wave transmission gratings were stored in the same location of silver-doped photopolymer film using peristrophic multiplexing techniques. Constant and variable exposure scheduling methods were adopted for storing gratings in the film using He–Ne laser (632.8 nm). The role of recording geometry on the dynamic range of the material was studied by comparing the results obtained from both techniques. Peristrophic multiplexing with rotation of the film in a plane normal to the bisector of the incident beams resulted in better homogenization of diffraction efficiencies and larger /# value.

  18. Fiber Bragg Grating Based Thermometry

    CERN Document Server

    Ahmed, Zeeshan; Guthrie, William; Quintavalle, John

    2016-01-01

    In recent years there has been considerable interest in developing photonic temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to resistance thermometry. In this study we examine the thermal response of FBGs over the temperature range of 233 K to 393 K. We demonstrate, in a hermetically sealed dry Argon environment, that FBG devices show a quadratic dependence on temperature with expanded uncertainties (k = 2) of ~500 mK. Our measurements indicate that the combined measurement uncertainty is dominated by uncertainty in determining the peak center fitting and by thermal aging of polyimide coated fibers.

  19. Analytical and numerical study on grating depth effects in grating coupled waveguide sensors

    DEFF Research Database (Denmark)

    Horvath, R.; Wilcox, L.C.; Pedersen, H.C.;

    2005-01-01

    . Analytical expressions are derived both for the position and width of the in-coupling peaks to illustrate the effects of grating depth on the guided mode resonances in grating coupled waveguide sensors. Numerical computations verify the model for shallow gratings both in terms of peak shape and position......The in-coupling process for grating-coupled planar optical waveguide sensors is investigated in the case of TE waves. A simple analytical model based on the Rayleigh-Fourier-Kiselev method is applied to take into account the depth of the grating coupler, which is usually neglected in the modeling...

  20. A New Idea and Technique of Fiber Gratings and Photodetectors in Broad-band Fiber Communication Systems

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Contents of this thesis are supported by the National Natural Foudation of China under Contract No.69625101, and the item is named “Tunable Optical Technology in Wavelength Division Multiplexing (WDM)” and is under charge of Professor Ren Xiaomin. They are also supported by subject 307 in National Program “863”: i.e., RCE photodetectors (PDs) used in Wavelength Division Multiplexing. Fiber Bragg Gratings (FBGs) have emerged as important optical fiber passive components in a variety of light-wave applications. It is expected that FBGs will play a key role in the next generation of optical fiber communication systems and sensor fileds. Most of these applications are based on the narrow-band reflection of FBGs. In this thesis, transmission dispersion, nonlinearity and tunability of FBGs are studied. The main contents are as follows: Transmission dispersion of FBGs is studied and the capability of dispersion compensation of FBGs is calculated theoretically. In the experiments, the dispersions of 10 Gb/s at 11.1 km and 22.22 km are compensated successfully by an unchirped fiber grating for the first time in China and the tunable compensation is achieved for the first time internationally. The scheme of tunable dispersion compensation using cascaded fiber gratings in WDM is analyzed and designed. It is indicated that the dispersion compensation in transmission using uniform fiber gratings is a better and more effective compensation scheme compared with the tradifitonal dispersion compensation using chirped fiber gratings. It is originally proposed that people can simulate characteristics of a long distance optical fiber by a short uniform fiber grating. This is verified for the first time experimentally. In the experiment, a short grating (about 1 cm) operated in transmission is used to simulate pulse broadening of 11.1 km optical fiber. This method can be used to detect performance of long distance transmission of communication systems. It is originally proposed

  1. Tilt sensitivity of the two-grating interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Christopher N.; Naulleau, Patrick P.

    2008-01-30

    Fringe formation in the two-grating interferometer is analyzed in the presence of a small parallelism error between the diffraction gratings assumed in the direction of grating shear. Our analysis shows that with partially coherent illumination, fringe contrast in the interference plane is reduced in the presence of nonzero grating tilt with the effect proportional to the grating tilt angle and the grating spatial frequencies. Our analysis also shows that for a given angle between the gratings there is an angle between the final grating and the interference plane that optimizes fringe contrast across the field.

  2. Instantaneous characteristics study of the diffracted and transmitted light of a static photorefractive reflection volume holographic grating read by an ultrashort pulse laser

    International Nuclear Information System (INIS)

    The time-domain diffraction and transmission of reflection volume holographic gratings (RVHGs) recorded in photorefractive LiNbO3 crystals are theoretically studied and compared with transmission volume holographic gratings (TVHGs) when they are illuminated by ultrashort pulse laser light. The modified Kogelnik's coupled-wave theory, combining the dispersion effect in the crystal, is used. The results show that larger diffraction intensity can be obtained by choosing a larger grating period, grating thickness and modulation index for a given pulse duration. The RVHG has higher diffraction intensity than the TVHG with the same grating parameters. Also, it is found that the diffracted pulse of the RVHG and the TVHG shift in opposite directions along the time-axis. The values of the shifts are functions of the readout pulse duration and grating parameters. The overmodulation phenomenon appears in the diffracted pulse of the TVHG at high values of the grating thickness and refractive index modulation, but it does not occur in the RVHG. The results of our study can be used in choosing proper grating parameters for pulse shaping and signal processing applications

  3. Chandra Finds Most Distant X-ray Galaxy Cluster

    Science.gov (United States)

    2001-02-01

    The most distant X-ray cluster of galaxies yet has been found by astronomers using NASA’s Chandra X-ray Observatory. Approximately 10 billion light years from Earth, the cluster 3C294 is 40 percent farther than the next most distant X-ray galaxy cluster. The existence of such a distant galaxy cluster is important for understanding how the universe evolved. "Distant objects like 3C294 provide snapshots to how these galaxy clusters looked billions of years ago," said Andrew Fabian of the Institute of Astronomy, Cambridge, England and lead author of the paper accepted for publication in the Monthly Notices of Britain’s Royal Astronomical Society. "These latest results help us better understand what the universe was like when it was only 20 percent of its current age." Chandra’s image reveals an hourglass-shaped region of X-ray emission centered on the previously known central radio source. This X-ray emission extends outward from the central galaxy for at least 300,000 light years and shows that the known radio source is in the central galaxy of a massive cluster. Scientists have long suspected that distant radio-emitting galaxies like 3C294 are part of larger groups of galaxies known as "clusters." However, radio data provides astronomers with only a partial picture of these distant objects. Confirmation of the existence of clusters at great distances - and, hence, at early stages of the universe - requires information from other wavelengths. Optical observations can be used to pinpoint individual galaxies, but X-ray data are needed to detect the hot gas that fills the space within the cluster. "Galaxy clusters are the largest gravitationally bound structures in the universe," said Fabian. "We do not expect to find many massive objects, such as the 3C294 cluster, in early times because structure is thought to grow from small scales to large scales." The vast clouds of hot gas that envelope galaxies in clusters are thought to be heated by collapse toward the

  4. Development of tilted fibre Bragg gratings using highly coherent 255 nm radiation

    Indian Academy of Sciences (India)

    O Prakash; J Kumar; R Mahakud; U Kumbhkar; S V Nakhe; S K Dixit

    2014-02-01

    This paper reports the study on development of tilted fibre Bragg gratings using highly coherent 255 nm radiation, obtained from the second harmonic generation (SHG) of copper vapour laser (CVL). The transmission and reflection spectra of the tilted fibre Bragg gratings (TFBG) were studied for the tilt angles of 0° (normal FBG), 1°, 3° and 4° between the fibre axis and the interference fringe plane. It was observed that as the angle of fibre axis and phase mask increased, the main Bragg peak shifted towards the higher wavelength and transmission dip decreased. The transmission dip of the cladding mode first increased and then decreased after reaching a maximum with the increase in the tilt angle.

  5. The spectral combination characteristic of grating and the bi-grating diffraction imaging effect

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper reports on a new property of grating, namely spectral combination, and on bi-grating diffraction imaging that is based on spectral combination. The spectral combination characteristic of a grating is the capability of combining multiple light beams of different wavelengths incident from specific angles into a single beam. The bi-grating diffraction imaging is the formation of the image of an object with two gratings: the first grating disperses the multi-color light beams from the object and the second combines the dispersed light beams to form the image. We gave the conditions necessary for obtaining the spectral combination. We also presented the equations that relate the two gratings’ spatial frequencies, diffraction orders and positions necessary for obtaining the bi-grating diffraction imaging.

  6. Inverse Scattering for Gratings and Wave Guides

    OpenAIRE

    Eskin, Gregory; Ralston, James; Yamamoto, Masahiro

    2007-01-01

    We consider the problem of unique identification of dielectric coefficients for gratings and sound speeds for wave guides from scattering data. We prove that the "propagating modes" given for all frequencies uniquely determine these coefficients. The gratings may contain conductors as well as dielectrics and the boundaries of the conductors are also determined by the propagating modes.

  7. Straw combustion on slow-moving grates

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    2005-01-01

    Combustion of straw in grate-based boilers is often associated with high emission levels and relatively poor fuel burnout. A numerical grate combustion model was developed to assist in improving the combustion performance of these boilers. The model is based on a one-dimensional ‘‘walking...

  8. Reflectivity-modulated grating-mirror

    DEFF Research Database (Denmark)

    2012-01-01

    to the oscillation axis. A modulated voltage (91) is applied in reverse bias between the n- and p-doped layers to modulate the refractive index of the electrooptic material layer (12) and thereby the reflectivity spectrum of the grating mirror (1). The reflectivity of the grating mirror (1) can be modulated between...

  9. Antireflective characteristics of hemispherical grid grating

    Institute of Scientific and Technical Information of China (English)

    REN Zhibin; JIANG Huilin; LIU Guojun; SUN Qiang

    2005-01-01

    In this paper, the optical characteristics of new type hemispherical grid subwavelength grating are studied by using multi-level column structure approximation and rigorous coupled-wave analysis. This kind of grating could be fabricated by chemical methods, thus simplifying the fabrication technology of subwavelength gratings for visible light. By computer simulation and calculation, the hemispherical grid subwavelength gratings are proved to have antireflective characteristics. Two design schemes of this kind of grating are presented. In the first scheme, the grating could achieve a reflectivity as low as 3.4416×10-7, which can be adapted to 0.46―0.7 μm of visible waveband and ±12° incident angle field. In the second scheme, the grating can achieve a reflectivity as low as 3.112×10-4 and adapted to the whole visible waveband and ±23° incident angle field. The application field of the latter scheme is wider than that of the former. The results of this paper could provide reference for the applications of the hemispherical grid subwavelength gratings for the visible waveband.

  10. Yes, High School Students Can Analyze Chandra Data

    Science.gov (United States)

    Keohane, J. W.; Clearfield, C. R.; Olbert, C. M.

    2002-12-01

    For the past two years, high school students at the North Carolina School of Science and Math (NCSSM) have worked with new and archival Chandra data, and have produced interesting scientific results. These results have included one refereed paper in the Ap.J., and about a dozen presentations at scientific meetings (including three at this meeting). The students were selected, based on interest, from the junior class at NCSSM, to stay on campus and work intensively for 2 to 4 weeks over the summer. Each team of students selected an object with public Chandra ACIS data, and were taught how to produce data products such as images and spectra, as well as conduct a literature search. In most cases, a paper had already been published using those data, and the students were usually able to reproduce the results. As the students waded through the literature, they would search for a theory to test or an interesting new phenomenon. Often the students would request an image in another wavelength to compare in detail to the Chandra data. After the summer, many students continued to work throughout the following fall semester, producing a paper for submission to the Siemens Westinghouse Science and Technology Competition by the beginning of October. In the process of conducting research, the students learn to apply many physics concepts, and learn valuable scientific research and writing skills. Those students that choose to continue with astrophysics can often dive directly into a high-level research project immediately when they arrive at college. These programs have been funded by NASA, through E/PO grants attached to parent research grants.

  11. Finite-number-of-periods holographic gratings with finite-width incident beams: analysis using the finite-difference frequency-domain method

    Science.gov (United States)

    Wu, Shun-Der; Glytsis, Elias N.

    2002-10-01

    The effects of finite number of periods (FNP) and finite incident beams on the diffraction efficiencies of holographic gratings are investigated by the finite-difference frequency-domain (FDFD) method. Gratings comprising 20, 15, 10, 5, and 3 periods illuminated by TE and TM incident light with various beam sizes are analyzed with the FDFD method and compared with the rigorous coupled-wave analysis (RCWA). Both unslanted and slanted gratings are treated in transmission as well as in reflection configurations. In general, the effect of the FNP is a decrease in the diffraction efficiency with a decrease in the number of periods of the grating. Similarly, a decrease in incident-beam width causes a decrease in the diffraction efficiency. Exceptions appear in off-Bragg incidence in which a smaller beam width could result in higher diffraction efficiency. For beam widths greater than 10 grating periods and for gratings with more than 20 periods in width, the diffraction efficiencies slowly converge to the values predicted by the RCWA (infinite incident beam and infinite-number-of-periods grating) for both TE and TM polarizations. Furthermore, the effects of FNP holographic gratings on their diffraction performance are found to be comparable to their counterparts of FNP surface-relief gratings. 2002 Optical Society of America

  12. Chandra Observations of Tycho’s Supernova Remnant

    Indian Academy of Sciences (India)

    U. Hwang; R. Petre; A. E. Szymkowiak; S. S. Holt

    2002-03-01

    We present a new Chandra observation of Tycho’s supernova remnant with the Advanced CCD Imaging Spectrometer. Multicolor X-ray imaging reveals new details of the outer shock and ejecta. At energies between 4 and 6 keV, the outline of the outer shock is clearly revealed in X-rays for the first time. The distribution of the emission from lines of Si and Fe are confirmed to have a different morphology from each other, and the Si ejecta are shown to extend to the blast shock at several locations. Characteristic spectra of the outer shock and ejecta are also presented.

  13. "Hidden" Seyfert 2 Galaxies in the Chandra Deep Field North

    OpenAIRE

    Cardamone, Carolin N.; Moran, Edward C.; Kay, Laura E.

    2007-01-01

    We have compared the X-ray--to--optical flux ratios (F_x/F_opt) of absorbed active galactic nuclei (AGNs) in the Chandra Deep Field North (CDF-N) with those of nearby, optically classified Seyfert 2 galaxies. The comparison provides an opportunity to explore the extent to which the local population of absorbed AGNs can account for the properties of the distant, spectroscopically ambiguous sources that produce the hard X-ray background. Our nearby sample consists of 38 objects that well repres...

  14. A Million-Second Chandra View of Cassiopeia A

    CERN Document Server

    Hwang, U; Badenes, C; Berends, F A; Blondin, J M; Cioffi, D; Delaney, T A; Dewey, D; Fesen, R A; Flanagan, K A; Fryer, C L; Ghavamian, P; Hughes, J P; Morse, J A; Plucinsky, P P; Petre, R; Pohl, M; Rudnick, L; Sankrit, R; Slane, P O; Smith, R K; Vink, J; Warren, J S; Hwang, Una; Badenes, Carles; Berendse, Fred; Blondin, John; Cioffi, Denis; Laney, Tracey De; Dewey, Daniel; Fesen, Robert; Flanagan, Kathryn A.; Fryer, Christopher L.; Ghavamian, Parviz; Hughes, John P.; Morse, Jon A.; Plucinsky, Paul P.; Petre, Robert; Pohl, Martin; Rudnick, Lawrence; Sankrit, Ravi; Slane, Patrick O.; Smith, Randall K.; Vink, Jacco; Warren, Jessica S.

    2004-01-01

    We introduce a million-second observation of the supernova remnant Cassiopeia A with the Chandra X-ray Observatory. The bipolar structure of the Si-rich ejecta (NE jet and SW counterpart) is clearly evident in the new images, and their chemical similarity is confirmed by their spectra. These are most likely due to jets of ejecta as opposed to cavities in the circumstellar medium, since we can reject simple models for the latter. The properties of these jets and the Fe-rich ejecta will provide clues to the explosion of Cas A.

  15. Chandra Sees Shape of Universe During Formative, Adolescent Years

    Science.gov (United States)

    2003-03-01

    Scientists using NASA's Chandra X-ray Observatory have taken a snapshot of the adolescent universe from about five billion years ago when the familiar web-like structure of galaxy chains and voids first emerged. The observation reveals distant and massive galaxies dotting the sky, clustered together under the gravitational attraction of deep, unseen pockets of dark matter. This provides important clues of how the universe matured from its chaotic beginnings to its elegant structure we see today. These results are presented today in a press conference at the meeting of the High Energy Astrophysics Division of the American Astronomical Society at Mt. Tremblant, Quebec. "Piece by piece, we are assembling a photo album of the universe through the ages," said Yuxuan Yang, a doctorate candidate at the University of Maryland, College Park, who conducted the analysis. "Last month we saw a picture of the infant universe taken with the Wilkinson Microwave Anisotropy Probe. Now we can add a snapshot of its adolescence." The Chandra observation traced a patch of sky known as the Lockman Hole in the constellation Ursa Major (containing the Big Dipper). Chandra saw a rich density of active galaxies, seven times denser than what has been detected in previous optical and radio surveys at similar distances. This provides the clearest picture yet at the large-scale structure of the universe at such distances (and age), according to Dr. Richard Mushotzky of NASA Goddard Space Flight Center in Greenbelt, Md., who led the observation. Lockman Hole JPEG, TIFF, PS An image that has been "blurred" to allow better view of the structures outlined by the X-ray sources. The color represents the spectra of the AGN. The red color indicates the sources on average radiates at longer wavelength while green and blue colors indicates the sources radiates at shorter wavelength. The Green and blue regions appear to form a wall, or shows more lumpiness than the "red" sources. If one could capture the

  16. The discovery of X-rays from Venus with Chandra

    OpenAIRE

    Dennerl, K.; Burwitz, V.; Englhauser, J.; Lisse, C.; Wolk, S.

    2002-01-01

    On January 10 and 13, 2001, Venus was observed for the first time with an X-ray astronomy satellite. The observation, performed with the ACIS-I and LETG/ACIS-S instruments on Chandra, yielded data of high spatial, spectral, and temporal resolution. Venus is clearly detected as a half-lit crescent, with considerable brightening on the sunward limb. The morphology agrees well with that expected from fluorescent scattering of solar X-rays in the planetary atmosphere. The radiation is observed at...

  17. Discovery of X-rays from Venus with Chandra

    OpenAIRE

    Dennerl, K.; Burwitz, V.; Englhauser, J.; Lisse, C.; Wolk, S.

    2002-01-01

    On January 10 and 13, 2001, Venus was observed for the first time with an X-ray astronomy satellite. The observation, performed with the ACIS-I and LETG/ACIS-S instruments on Chandra, yielded data of high spatial, spectral, and temporal resolution. Venus is clearly detected as a half-lit crescent, with considerable brightening on the sunward limb. The morphology agrees well with that expected from fluorescent scattering of solar X-rays in the planetary atmosphere. The radiation is observed at...

  18. Discovery of X-rays from Mars with Chandra

    OpenAIRE

    Dennerl, Konrad

    2002-01-01

    On 4 July 2001, X-rays from Mars were detected for the first time. The observation was performed with the ACIS-I detector onboard Chandra and yielded data of high spatial and temporal resolution, together with spectral information. Mars is clearly detected as an almost fully illuminated disk, with an indication of limb brightening at the sunward side, accompanied by some fading on the opposite side. The morphology and the X-ray luminosity of ~4 MW are fully consistent with fluorescent scatter...

  19. A Chandra Proper Motion for PSR J1809-2332

    CERN Document Server

    Van Etten, Adam; Ng, C -Y

    2012-01-01

    We report on a new Chandra exposure of PSR J1809-2332, the recently discovered pulsar powering the bright EGRET source 3EG J1809-2328. By registration of field X-ray sources in an archival exposure, we measure a significant proper motion for the pulsar point source over an ~11 year baseline. The shift of 0.30+/-0.06" (at PA= 153.3+/-18.4) supports an association with proposed SNR parent G7.5-1.7. Spectral analysis of diffuse emission in the region also supports the interpretation as a hard wind nebula trail pointing back toward the SNR.

  20. A Chandra Proper Motion for PSR J1809-2332

    OpenAIRE

    Van Etten, Adam; Romani, Roger W.; Ng, C. -Y.

    2012-01-01

    We report on a new Chandra exposure of PSR J1809-2332, the recently discovered pulsar powering the bright EGRET source 3EG J1809-2328. By registration of field X-ray sources in an archival exposure, we measure a significant proper motion for the pulsar point source over an ~11 year baseline. The shift of 0.30+/-0.06" (at PA= 153.3+/-18.4) supports an association with proposed SNR parent G7.5-1.7. Spectral analysis of diffuse emission in the region also supports the interpretation as a hard wi...

  1. Chandra Observes the End of an Era SN 1987A

    OpenAIRE

    Frank, Kari A.; Zhekov, Svetozar A.; Park, Sangwook; McCray, Richard; Dwek, Eli; Burrows, David N.

    2016-01-01

    Updated imaging and photometric results from Chandra observations of SN 1987A, covering the last 16 years, are presented. We find that the 0.5-2 keV light curve has remained constant at ~8x10^-12 erg s^-1 cm^-2 since 9500 days, with the 3-8 keV light curve continuing to increase until at least 10000 days. The expansion rate of the ring is found to be energy dependent, such that after day 6000 the ring expands faster in the 2-10 keV band than it does at energies

  2. Chandra Discovers Eruption and Pulsation in Nova Outburst

    Science.gov (United States)

    2001-09-01

    NASA's Chandra X-ray Observatory has discovered a giant outburst of X-rays and unusual cyclical pulsing from a white dwarf star that is closely orbiting another star -- the first time either of these phenomena has been seen in X-rays. The observations are helping scientists better understand the thermonuclear explosions that occur in certain binary star systems. The observations of Nova Aquilae were reported today at the "Two Years of Science with Chandra" symposium by an international team led by Sumner Starrfield of Arizona State University. "We found two important results in our Chandra observations. The first was an underlying pulsation every 40 minutes in the X-ray brightness, which we believe comes from the cyclical expansion and contraction of the outer layers of the white dwarf," said Starrfield. "The other result was an enormous flare of X-rays that lasted for 15 minutes. Nothing like this has been seen before from a nova, and we don't know how to explain it." Novas occur on a white dwarf (a star which used up all its nuclear fuel and shrank to roughly the size of the Earth) that is orbiting a normal size star. Strong gravity tides drag hydrogen gas off the normal star and onto the white dwarf, where it can take more than 100,000 years for enough hydrogen to accumulate to ignite nuclear fusion reactions. Gradually, these reactions intensify until a cosmic-sized hydrogen bomb blast results. The outer layers of the white dwarf are then blown away, producing a nova outburst that can be observed for a period of months to years as the material expands into space. "Chandra has allowed us to see deep into the gases ejected by this giant explosion and extract unparalleled information on the evolution of the white dwarf whose surface is exploding," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics. The brightening of Nova Aquilae was first detected by optical astronomers in December 1999. "Although this star is at a distance of more than 6

  3. Alignment free characterization of 2D gratings

    CERN Document Server

    Madsen, Morten Hannibal; Hansen, Poul-Erik; Jørgensen, Jan Friis

    2015-01-01

    Fast characterization of 2-dimensional gratings is demonstrated using a Fourier lens optical system and a differential optimization algorithm. It is shown that both the grating specific parameters such as the basis vectors and the angle between them and the alignment of the sample, such as the rotation of the sample around the x-, y-, and z-axis, can be deduced from a single measurement. More specifically, the lattice vectors and the angle between them have been measured, while the corrections of the alignment parameters are used to improve the quality of the measurement, and hence reduce the measurement uncertainty. Alignment free characterization is demonstrated on both a 2D hexagonal grating with a period of 700 nm and a checkerboard grating with a pitch of 3000 nm. The method can also be used for both automatic alignment and in-line characterization of gratings.

  4. Compact imaging spectrometer utilizing immersed gratings

    Energy Technology Data Exchange (ETDEWEB)

    Chrisp, Michael P. (Danville, CA); Lerner, Scott A. (Corvallis, OR); Kuzmenko, Paul J. (Livermore, CA); Bennett, Charles L. (Livermore, CA)

    2007-07-03

    A compact imaging spectrometer with an immersive diffraction grating that compensates optical distortions. The imaging spectrometer comprises an entrance slit for transmitting light, means for receiving the light and directing the light, an immersion grating, and a detector array. The entrance slit, the means for receiving the light, the immersion grating, and the detector array are positioned wherein the entrance slit transmits light to the means for receiving the light and the means for receiving the light directs the light to the immersion grating and the immersion grating receives the light and directs the light to the means for receiving the light, and the means for receiving the light directs the light to the detector array.

  5. Historical Remembrances of the Chandra X-ray Observatory: How Partnerships Created Success

    Science.gov (United States)

    Burke, Robert

    2009-09-01

    As the astronomy community plans for new ventures in space, we're forced to find creative solutions to operate within the ever increasing fiscal constraints of the current economic environment. The Chandra X-ray Observatory program offers an example of how missions can be successfully developed within manageable budget constraints. The ten year anniversary offers us the chance to look back at the Chandra team's special partnership between scientists, managers, and industry that led to our success.Chandra experienced many of the challenges common to major observatories: state-of-the-art technical requirements, budget-induced slips, and restructurings. Yet the Chandra team achieved excellent performance for dramatically lower cost. In fact, Chandra completed its prime mission for billions of dollars less than originally planned. In 1992, NASA MSFC and Northrop Grumman (then TRW) together led a major restructure that saved approximately 3.4B in program cost, while we improved the imaging capability and observing efficiency of Chandra. This was accomplished by a combination of team-work, systems engineering, advanced technology insertion, and effective approaches for program implementation, combined with a high performance culture that aligned goals and focused on mission success. Northrop Grumman is proud of our role in supporting the NASA Marshall Space Flight Center and our academic partners in advancing the frontiers of x-ray astronomy and scientific discovery with Chandra. As Chandra continues its extended mission, the observatory continues to provide superb scientific performance.

  6. Chandra and XMM–Newton Observations of H2O Maser Galaxy Mrk 348

    Indian Academy of Sciences (India)

    J. Wang; J. S. Zhang; Q. Guo

    2014-09-01

    For H2O megamaser galaxy Mrk 348, Chandra and XMM–Newton data are analysed. The nuclear fitting results of XMM–Newton data suggest the possible existence of a heavily obscured AGN. But the nuclear spectrum extracted from Chandra cannot be well-fitted by the best fitting model for XMM–Newton. Further optimal fitting and discussions are needed.

  7. Tumour visualisation in human soft tissue using grating-based X-ray phase contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Herzen, Julia; Willner, Marian; Schleede, Simone; Bech, Martin; Tapfer, Arne; Stockmar, Marco; Achterhold, Klaus; Pfeiffer, Franz [Department of Physics (E17) and Institute of Medical Engineering (IMETUM), Technische Universitaet Muenchen (Germany)

    2011-07-01

    The grating-based phase-contrast imaging provides enhanced image structure details, which are partly complementary or even not attainable with standard X-ray absorption imaging. Especially in the case of biological soft tissue when standard x-ray radiography is often limited due to the weak absorption contrast, this method represents a real alternative. Based on X-ray optical transmission gratings this modality has transferred the phase-contrast imaging from the highly brilliant synchrotron radiation sources to conventional laboratory-based broadband x-ray tubes. Here, we present a study on human soft tissue specimens containing tumours using the grating-based phase contrast imaging at both highly brilliant synchrotron (ESRF, Grenoble), and at conventional X-ray laboratory radiation sources. Our results demonstrate a superior contrast for different kinds of soft tissue in the phase contrast and verify this imaging modality to be a promising candidate to establish phase-contrast imaging in clinical radiology.

  8. Numerical investigation of slow solitons in Bragg gratings with a hyperbolic tangent apodization

    International Nuclear Information System (INIS)

    This paper numerically and analytically investigates the formation and propagation motion of optical soliton in the Bragg grating. We choose the fibre Bragg grating with hyperbolic tangent apodization in the middle section in order to obtain slower solitons. Optical fibre soliton but not Bragg grating soliton is used as input pulse in the discussion, which is much more approximate to the light source for the practical purpose. We discuss in detail the effects of the soliton's velocity with some parameters in the process of transmission. The results show that by choosing special parameters, one can make the soliton slow-down with a little distortion and energy decay and obtain tunable time-delay on a small scale. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  9. Spectrometer sensor using patterned nano-structure plasmon resonance grating (Conference Presentation)

    Science.gov (United States)

    Guo, Hong; Tian, Xueli; Guo, Junpeng

    2016-03-01

    Localized surface plasmon resonance has been extensively investigated for biochemical sensor applications. In traditional localized surface plasmon resonance biosensors, resonance spectra were measured in the reflection or transmission from the nanostructure devices. In this work, we demonstrate a new surface plasmon resonance sensor platform with which the localized surface plasmon resonance and shift were measured by using a CCD imager instead of using an optical spectrometer. In additional to the metal nanostructures which support localized plasmon resonance, we pattern the nanostructures into diffraction gratings with super-wavelength grating periods. The nanostructure diffraction gratings support localized plasmon resonance and also diffract localized plasmon resonance radiations into non-zeroth order diffractions. Plasmon resonance spectrum and shift are measured with a CCD imager in one of the diffraction orders. The new plasmon resonance spectrometer sensor combines the functions of sensing and spectral analysis into one apparatus and is capable of real-time visualization of the biochemical bonding process with an imager.

  10. Numerical investigation of slow solitons in Bragg gratings with a hyperbolic tangent apodization

    Institute of Scientific and Technical Information of China (English)

    Wang Kui-Ru; Cheng Jie-Lin; Sang Xin-Zhu; Chen Gong

    2011-01-01

    This paper numerically and analytically investigates the formation and propagation motion of optical soliton in the Bragg grating. We choose the fibre Bragg grating with hyperbolic tangent apodization in the middle section in order to obtain slower solitons. Optical fibre soliton but not Bragg grating soliton is used as input pulse in the discussion, which is much more approximate to the light source for the practical purpose. We discuss in detail the effects of the soliton's velocity with some parameters in the process of transmission. The results show that by choosing special parameters, one can make the soliton slow-down with a little distortion and energy decay and obtain tunable time-delay on a small scale.

  11. Fano-like coupling between two oppositely enhanced processes by diffraction in a dielectric grating.

    Science.gov (United States)

    Zhang, Jian; Zhang, Xinping

    2015-11-16

    Fano-like coupling was investigated extensively in plasmonic nanostructures, which is based on the interaction between the photonic and plasmonic resonance modes. Metallic photonic crystals consisting of waveguide metallic gratings are typical devices exhibiting strong Fano-coupling between waveguide and plasmon resonance modes. However, we demonstrate here that similar effects can also be achieved in waveguide dielectric grating structures. In this case, the broad-band strong optical extinction results from multifold diffraction processes, instead of the plasmonic absorption and scattering of light. The diffraction efficiency of the waveguide dielectric gratings was tuned by changing the duty cycle through adjusting the exposure time in interference lithography. Enhanced diffraction efficiency reduces the direct transmission while enhances the waveguide resonance mode, leading to a Fano-like coupling process. PMID:26698522

  12. Chandra X-ray Observations of the Young Stellar Cluster NGC 6193 in the Ara OB1 Association

    CERN Document Server

    Skinner, S L; Palla, F; Barbosa, C L D R

    2005-01-01

    A 90 ks Chandra HETG observation of the young stellar cluster NGC 6193 in the southern Ara OB1 association detected 43 X-ray sources in a 2' x 2' core region centered on the young O stars HD 150135 (O6.5V) and HD 150136 (O3+O6V). The cluster is dominated by exceptionally bright X-ray emission from the two O stars, which are separated by only 10 arcsecs. The X-ray luminosity of HD 150136 is log Lx = 33.39 (ergs/s), making it one of the most luminous O-star X-ray sources known. All of the fainter X-ray sources in the core region have near-IR counterparts, but JHK photometry provides little evidence for near-IR excesses. These core sources have typical mean photon energies of 2 keV and about one-third are variable. It is likely that some are young low-mass stars in the cluster, but cluster membership remains to be determined. Grating spectra show that the X-ray properties of HD 150135 and HD 150136 are similar, but not identical. Both have moderately broadened unshifted emission lines and their emission is domin...

  13. Chandra Observations of SN 1987A: The Soft X-Ray Light Curve Revisited

    Science.gov (United States)

    Helder, E. A.; Broos, P. S.; Dewey, D.; Dwek, E.; McCray, R.; Park, S.; Racusin, J. L.; Zhekov, S. A.; Burrows, D. N.

    2013-01-01

    We report on the present stage of SN 1987A as observed by the Chandra X-Ray Observatory. We reanalyze published Chandra observations and add three more epochs of Chandra data to get a consistent picture of the evolution of the X-ray fluxes in several energy bands. We discuss the implications of several calibration issues for Chandra data. Using the most recent Chandra calibration files, we find that the 0.5-2.0 keV band fluxes of SN 1987A have increased by approximately 6 x 10(exp-13) erg s(exp-1)cm(exp-2) per year since 2009. This is in contrast with our previous result that the 0.5-2.0 keV light curve showed a sudden flattening in 2009. Based on our new analysis, we conclude that the forward shock is still in full interaction with the equatorial ring.

  14. Multiwavelength campaign on Mrk 509 XIV. Chandra HETGS spectra

    CERN Document Server

    Kaastra, J S; Arav, N; Behar, E; Bianchi, S; Branduardi-Raymont, G; Cappi, M; Costantini, E; Kriss, G A; De Marco, B; Mehdipour, M; Paltani, S; Petrucci, P -O; Pinto, C; Ponti, G; Steenbrugge, K C; de Vries, C P

    2014-01-01

    We present in this paper the results of a 270 ks Chandra HETGS observation in the context of a large multiwavelength campaign on the Seyfert galaxy Mrk 509. The HETGS spectrum allows us to study the high ionisation warm absorber and the Fe-K complex in Mrk 509. We search for variability in the spectral properties of the source with respect to previous observations in this campaign, as well as for evidence of ultra-fast outflow signatures. The Chandra HETGS X-ray spectrum of Mrk 509 was analysed using the SPEX fitting package. We confirm the basic structure of the warm absorber found in the 600 ks XMM-Newton RGS observation observed three years earlier, consisting of five distinct ionisation components in a multikinematic regime. We find little or no variability in the physical properties of the different warm absorber phases with respect to previous observations in this campaign, except for component D2 which has a higher column density at the expense of component C2 at the same outflow velocity (-240 km/s). ...

  15. The Chandra COSMOS Survey, I: Overview and Point Source Catalog

    CERN Document Server

    Elvis, Martin; Vignali, Cristian; Puccetti, Simonetta; Fiore, Fabrizio; Cappelluti, Nico; Aldcroft, T L; Fruscione, Antonella; Zamorani, G; Comastri, Andrea; Brusa, Marcella; Gilli, Roberto; Miyaji, Takamitsu; Koekemoer, Francesco Damiani Anton; Finoguenov, Alexis; Brunner, Hermann; Urry, C M; Silverman, John; Mainieri, Vincenzo; Hasinger, Guenther; Griffiths, Richard; Carollo, Marcella; Hao, Heng; Guzzo, Luigi; Blain, Andrew; Calzetti, Daniela; Carilli, C; Capak, Peter; Ettori, Stefano; Fabbiano, Giuseppina; Impey, Chris; Lilly, Simon; Mobasher, Bahram; Rich, Michael; Salvato, Mara; Sanders, D B; Schinnerer, Eva; Scoville, N; Shopbell, Patrick; Taylor, James E; Taniguchi, Yoshiaki; Volonteri, Marta

    2009-01-01

    The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra} program that has imaged the central 0.5 sq.deg of the COSMOS field (centered at 10h, +02deg) with an effective exposure of ~160ksec, and an outer 0.4sq.deg. area with an effective exposure of ~80ksec. The limiting source detection depths are 1.9e-16 erg cm^-2 s$-1 in the Soft (0.5-2 keV) band, 7.3e^-16 erg cm^-2 s^-1 in the Hard (2-10 keV) band, and 5.7e^-16 erg cm^-2 s^-1 in the Full (0.5-10 keV) band. Here we describe the strategy, design and execution of the C-COSMOS survey, and present the catalog of 1761 point sources detected at a probability of being spurious of <2e^-5 (1655 in the Full, 1340 in the Soft, and 1017 in the Hard bands). By using a grid of 36 heavily (~50%) overlapping pointing positions with the ACIS-I imager, a remarkably uniform (to 12%) exposure across the inner 0.5 sq.deg field was obtained, leading to a sharply defined lower flux limit. The widely different PSFs obtained in each exposure at each point in the field r...

  16. The Chandra COSMOS Legacy survey: optical/IR identifications

    CERN Document Server

    Marchesi, S; Elvis, M; Salvato, M; Brusa, M; Comastri, A; Gilli, R; Hasinger, G; Lanzuisi, G; Miyaji, T; Treister, E; Urry, C M; Vignali, C; Zamorani, G; Allevato, V; Cappelluti, N; Cardamone, C; Finoguenov, A; Griffiths, R E; Karim, A; Laigle, C; LaMassa, S M; Jahnke, K; Ranalli, P; Schawinski, K; Schinnerer, E; Silverman, J D; Smolcic, V; Suh, H; Trakhtenbrot, B

    2015-01-01

    We present the catalog of optical and infrared counterparts of the Chandra COSMOS-Legacy Survey, a 4.6 Ms Chandra program on the 2.2 square degrees of the COSMOS field, combination of 56 new overlapping observations obtained in Cycle 14 with the previous C-COSMOS survey. In this Paper we report the i, K, and 3.6 micron identifications of the 2273 X-ray point sources detected in the new Cycle 14 observations. We use the likelihood ratio technique to derive the association of optical/infrared (IR) counterparts for 97% of the X-ray sources. We also update the information for the 1743 sources detected in C-COSMOS, using new K and 3.6 micron information not available when the C-COSMOS analysis was performed. The final catalog contains 4016 X-ray sources, 97% of which have an optical/IR counterpart and a photometric redshift, while 54% of the sources have a spectroscopic redshift. The full catalog, including spectroscopic and photometric redshifts and optical and X-ray properties described here in detail, is availa...

  17. Chandra Observes the End of an Era SN 1987A

    CERN Document Server

    Frank, Kari A; Park, Sangwook; McCray, Richard; Dwek, Eli; Burrows, David N

    2016-01-01

    Updated imaging and photometric results from Chandra observations of SN 1987A, covering the last 16 years, are presented. We find that the 0.5-2 keV light curve has remained constant at ~8x10^-12 erg s^-1 cm^-2 since 9500 days, with the 3-8 keV light curve continuing to increase until at least 10000 days. The expansion rate of the ring is found to be energy dependent, such that after day 6000 the ring expands faster in the 2-10 keV band than it does at energies <2 keV. Images show a reversal of the east-west asymmetry between 7000 and 8000 days after the explosion. The latest images suggest the southeastern side of the equatorial ring is beginning to fade. Consistent with the latest optical and infrared results, our Chandra analysis indicates the blast wave is now leaving the dense equatorial ring, which marks the beginning of a major change in the evolutionary phase of the supernova remnant 1987A.

  18. Chandra Identification of Two AGN Discovered by INTEGRAL

    CERN Document Server

    Tomsick, John A; Rahoui, Farid; Ajello, Marco; Rodriguez, Jerome; Barriere, Nicolas; Bodaghee, Arash; Chaty, Sylvain

    2015-01-01

    Here, we report on observations of two hard X-ray sources that were originally discovered with the INTEGRAL satellite: IGR J04059+5416 and IGR J08297-4250. We use the Chandra X-ray Observatory to localize the sources and then archival near-IR images to identify the counterparts. Both sources have counterparts in the catalog of extended 2 Micron All-Sky Survey sources, and the counterpart to IGR J04059+5416 has been previously identified as a galaxy. Thus, we place IGR J04059+5416 in the class of Active Galactic Nuclei (AGN), and we suggest that IGR J08297-4250 is also an AGN. If this identification is correct, the near-IR images suggest that the host galaxy of IGR J08297-4250 may be merging with a smaller nearby galaxy. For IGR J04059+5416, the 0.3-86 keV spectrum from Chandra and INTEGRAL is consistent with an absorbed power-law with a column density of N_H = 3.1(+2.0)(-1.5)e22 cm-2 and a photon index of Gamma = 1.4+/-0.7, and we suggest that it is a Seyfert galaxy. For IGR J08297-4250, the photon index is s...

  19. Spatial Correlation Function of the Chandra Selected Active Galactic Nuclei

    Science.gov (United States)

    Yang, Y.; Mushotzky, R. F.; Barger, A. J.; Cowie, L. L.

    2006-01-01

    We present the spatial correlation function analysis of non-stellar X-ray point sources in the Chandra Large Area Synoptic X-ray Survey of Lockman Hole Northwest (CLASXS). Our 9 ACIS-I fields cover a contiguous solid angle of 0.4 deg(exp 2) and reach a depth of 3 x 10(exp -15) erg/square cm/s in the 2-8 keV band. We supplement our analysis with data from the Chandra Deep Field North (CDFN). The addition of this field allows better probe of the correlation function at small scales. A total of 233 and 252 sources with spectroscopic information are used in the study of the CLASXS and CDFN fields respectively. We calculate both redshift-space and projected correlation functions in co-moving coordinates, averaged over the redshift range of 0.1 luminosity and clustering amplitude is weak, which, however, is fully consistent with the expectation using the simplest relations between X-ray luminosity, black hole mass, and dark halo mass. We study the evolution of the AGN clustering by dividing the samples into 4 redshift bins over 0.1 Mpcmass of the dark matter halo derived from the bias estimates show little change with redshift. The average halo mass is found to be log (M(sub halo)/M(sun))approximates 12.1. Subject headings: cosmology: observations - large-scale structure of the universe - x-rays: diffuse background - galaxies: nuclei

  20. Chandra Opens New Line of Investigation on Dark Energy

    Science.gov (United States)

    2004-05-01

    Astronomers have detected and probed dark energy by applying a powerful, new method that uses images of galaxy clusters made by NASA's Chandra X-ray Observatory. The results trace the transition of the expansion of the Universe from a decelerating to an accelerating phase several billion years ago, and give intriguing clues about the nature of dark energy and the fate of the Universe. "Dark energy is perhaps the biggest mystery in physics," said Steve Allen of the Institute of Astronomy (IoA) at the University of Cambridge in England, and leader of the study. "As such, it is extremely important to make an independent test of its existence and properties." Abell 2029 Chandra X-ray Image of Abell 2029 Allen and his colleagues used Chandra to study 26 clusters of galaxies at distances corresponding to light travel times of between one and eight billion years. These data span the time when the Universe slowed from its original expansion, before speeding up again because of the repulsive effect of dark energy. "We're directly seeing that the expansion of the Universe is accelerating by measuring the distances to these galaxy clusters," said Andy Fabian also of the IoA, a co-author on the study. The new Chandra results suggest that the dark energy density does not change quickly with time and may even be constant, consistent with the "cosmological constant" concept first introduced by Albert Einstein. If so, the Universe is expected to continue expanding forever, so that in many billions of years only a tiny fraction of the known galaxies will be observable. More Animations Animation of the "Big Rip" If the dark energy density is constant, more dramatic fates for the Universe would be avoided. These include the "Big Rip," where dark energy increases until galaxies, stars, planets and eventually atoms are eventually torn apart. The "Big Crunch," where the Universe eventually collapses on itself, would also be ruled out. Chandra's probe of dark energy relies on the unique

  1. The BMW-Chandra survey. Serendipitous Source Catalogue

    CERN Document Server

    Romano, P; Campana, S; Moretti, A; Panzera, M R; Tagliaferri, G; Mottini, M

    2009-01-01

    We present the BMW-Chandra source catalogue derived from Chandra ACIS-I observations (exposure time >10ks) public as of March 2003 by using a wavelet detection algorithm (Lazzati et al. 1999; Campana et al. 1999). The catalogue contains a total of 21325 sources, 16758 of which are serendipitous. Our sky coverage in the soft band (0.5-2 keV, S/N =3) is ~8 deg^2 for F_X > 10^-13 erg cm^-2 s-1, and ~2 deg^2 for F_X >10^-15 erg cm^-2 s^-1. The catalogue contains information on positions, count rates (and errors) in three energy bands. (total, 0.5-7 keV; soft, 0.5-2 keV; and hard, 2-7keV), and in four additional energy bands, SB1 (0.5-1keV), SB2 (1-2 keV), HB1 (2-4 keV), and HB2 (4-7keV), as well as information on the source extension, and cross-matches with the FIRST, IRAS, 2MASS, and GSC-2 catalogues.

  2. The BMW-Chandra survey. Serendipitous Source Catalogue

    Science.gov (United States)

    Romano, P.; Mignani, R. P.; Campana, S.; Moretti, A.; Panzera, M. R.; Tagliaferri, G.; Mottini, M.

    2009-07-01

    We present the BMW-Chandra source catalogue derived from Chandra ACIS-I observations (exposure time > 10ks) public as of March 2003 by using a wavelet detection algorithm (Lazzati et al. 1999; Campana et al. 1999). The catalogue contains a total of 21325 sources, 16758 of which are serendipitous. Our sky coverage in the soft band (0.5-2keV, S/N=3) is ~ 8 deg2 for FX ≥ 10-13 erg cm-2 s-1, and ~ 2 deg2 for FX ≥ 10-15 erg cm-2 s-1. The catalogue contains information on positions, count rates (and errors) in three energy bands (total, 0.5-7keV; soft, 0.5-2keV; and hard, 2-7keV), and in four additional energy bands, SB1 (0.5-1keV), SB2 (1-2keV), HB1 (2-4keV), and HB2 (4-7keV), as well as information on the source extension, and cross-matches with the FIRST, IRAS, 2MASS, and GSC-2 catalogues.

  3. A Deep Chandra ACIS Survey of M51

    Science.gov (United States)

    Kuntz, K. D.; Long, Knox S.; Kilgard, Roy E.

    2016-08-01

    We have obtained a deep X-ray image of the nearby galaxy M51 using Chandra. Here we present the catalog of X-ray sources detected in these observations and provide an overview of the properties of the point-source population. We find 298 sources within the D 25 radii of NGC 5194/5, of which 20% are variable, a dozen are classical transients, and another half dozen are transient-like sources. The typical number of active ultraluminous X-ray sources in any given observation is ˜5, and only two of those sources persist in an ultraluminous state over the 12 yr of observations. Given reasonable assumptions about the supernova remnant population, the luminosity function is well described by a power law with an index between 1.55 and 1.7, only slightly shallower than that found for populations dominated by high-mass X-ray binaries (HMXBs), which suggests that the binary population in NGC 5194 is also dominated by HMXBs. The luminosity function of NGC 5195 is more consistent with a low-mass X-ray binary dominated population. Based on observations made with NASA's Chandra X-ray Observatory, which is operated by the Smithsonian Astrophysical Observatory under contract #NAS83060, and the data were obtained through program GO1-12115.

  4. Grating assisted optical waveguide coupler to excite individual modes of a multi-mode waveguide

    Science.gov (United States)

    Bremer, K.; Lochmann, S.; Roth, B.

    2015-12-01

    Spatial division multiplexing (SDM) in the form of mode division multiplexing (MDM) in multi-mode (MM) waveguides is currently explored to overcome the capacity limitation of single-mode (SM) waveguides in data transmission technology. In this work a new approach towards mode selective optical waveguide couplers to multiplex and demultiplex individual modes of MM waveguides is presented. We discuss a grating assisted mode selective optical waveguide coupler and evaluate numerically its coupling efficiency. The approach relies on a grating structure in a SM waveguide which is used to excite individual modes of an adjacent unmodified MM waveguide via evanescent field coupling. The simulations verify that by using the grating structure and tailoring the grating period, light from the SM waveguide can be coupled selectively into the fundamental mode or any higher-order mode of a MM waveguide with high efficiency and low crosstalk to adjacent mode-channels. The results indicate the potential of the grating assisted waveguide coupler approach for future applications in on-chip photonic networks and the (de)multiplexing of individual modes of MM waveguides.

  5. Application of Metallic Strip Gratings for Enhancement of Electromagnetic Performance of A-sandwich Radome

    Directory of Open Access Journals (Sweden)

    Raveendranath U. Nair

    2013-09-01

    Full Text Available Enhancement of the electromagnetic (EM performance characteristics of A-sandwich radome wall over X-band using metallic strip gratings is presented in this work. Equivalent transmission line method in conjunction with equivalent circuit model (ECM is used for modeling the A-sandwich radome panel with metallic strip gratings and the computation of radome performance parameters. Metallic strip grating embedded in the mid-plane of the core and those in the skin-core interface are the configurations considered in the present work. For a given thickness of metallic strip grating, its width and pitch are optimized at different angles of incidence such that the new radome wall configuration offers superior EM performance over the entire X-band as compared to the conventional A-sandwich wall. The EM analysis shows that the superior EM performance of A-sandwich with metallic strip gratings makes it suitable for the design of normal incidence and streamlined airborne radomes.Defence Science Journal, 2013, 63(5, pp.508-514, DOI:http://dx.doi.org/10.14429/dsj.63.2458

  6. One-dimensional space resolving flat-field holographic grating soft x-ray framing camera spectrograph for laser plasma diagnostics

    International Nuclear Information System (INIS)

    A 1D space resolving x-ray spectrum diagnostic system has been developed to study the radiation opacity of hot plasma on SG-II laser facility. The diagnostic system consists of a 2400 lines/mm flat-field holographic grating and a gated microchannel plate coupled with an optical CCD and covers the wavelength range of 5-50 A. The holographic grating was compared with a ruled one by measuring the emission spectra from a laser-produced molybdenum plasma. The results indicate that the holographic grating possesses better sensitivity than the ruled grating having nearly similar spectral resolution. The spectrograph has been used in radiative opacity measurement of Fe plasma. Simultaneous measurements of the backlight source and the transmission spectrum in appointed time range in one shot have been accomplished successfully with the holographic grating spectrometer. The 2p-3d transition absorption of Fe plasma near 15.5A in has been observed clearly.

  7. One-dimensional space resolving flat-field holographic grating soft x-ray framing camera spectrograph for laser plasma diagnostics

    Science.gov (United States)

    Xiong, Gang; Hu, Zhimin; Li, Hang; Zhao, Yang; Shang, Wanli; Zhu, Tuo; Wei, Minxi; Yang, Guohong; Zhang, Jiyan; Yang, Jiamin

    2011-04-01

    A 1D space resolving x-ray spectrum diagnostic system has been developed to study the radiation opacity of hot plasma on SG-II laser facility. The diagnostic system consists of a 2400 lines/mm flat-field holographic grating and a gated microchannel plate coupled with an optical CCD and covers the wavelength range of 5-50 Å. The holographic grating was compared with a ruled one by measuring the emission spectra from a laser-produced molybdenum plasma. The results indicate that the holographic grating possesses better sensitivity than the ruled grating having nearly similar spectral resolution. The spectrograph has been used in radiative opacity measurement of Fe plasma. Simultaneous measurements of the backlight source and the transmission spectrum in appointed time range in one shot have been accomplished successfully with the holographic grating spectrometer. The 2p-3d transition absorption of Fe plasma near 15.5Å in has been observed clearly.

  8. Second and third harmonic generation at UV and soft x-ray wavelengths from semiconductor gratings

    Science.gov (United States)

    Vincenti, M. A.; de Ceglia, D.; Scalora, M.

    2011-10-01

    Extraordinary transmission properties are demonstrated in the UV range for GaAs gratings with sub-wavelength apertures under TM-polarization excitation. The metal-like response below 270nm, typical of several semiconductors such as GaAs or GaP, in fact may be used to excite surface waves that lead to enhance transmission in the linear regime and for novel nonlinear optical phenomena in the UV and soft X-ray ranges. An investigation of the linear transmission as a function of geometrical parameters of the grating reveals the formation of surface waves and relatively high transmission values even in regimes where the nominal absorption is significant. Strong field localization in subwavelength cavities and on the surface of the grating can be achieved under proper excitation conditions leading to the enhancement of harmonic generation. Nonlinear contributions to harmonic generation arise from symmetry breaking, the nonlinear magnetic Lorentz force, and from intrinsic, dipolar volume contributions. Preliminary results show promising nonlinear conversion efficiencies at wavelengths below 100nm, and demonstrate cross-coupling of TE and TM polarizations for pump and harmonic signals. A down-conversion process that can re-generate pump photons of polarization orthogonal compared to the incident pump field is also demonstrated.

  9. Fiber Bragg Grating Sensors for Harsh Environments

    Directory of Open Access Journals (Sweden)

    Stephen J. Mihailov

    2012-02-01

    Full Text Available Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments.

  10. Thermal annealing of tilted fiber Bragg gratings

    Science.gov (United States)

    González-Vila, Á.; Rodríguez-Cobo, L.; Mégret, P.; Caucheteur, C.; López-Higuera, J. M.

    2016-05-01

    We report a practical study of the thermal decay of cladding mode resonances in tilted fiber Bragg gratings, establishing an analogy with the "power law" evolution previously observed on uniform gratings. We examine how this process contributes to a great thermal stability, even improving it by means of a second cycle slightly increasing the annealing temperature. In addition, we show an improvement of the grating spectrum after annealing, with respect to the one just after inscription, which suggests the application of this method to be employed to improve saturation issues during the photo-inscription process.

  11. An electromagnetically induced grating by microwave modulation

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Zhi-Hong; Shin, Sung Guk; Kim, Kisik, E-mail: kisik@inha.ac.k [Department of Physics, Inha University, Incheon 402-751 (Korea, Republic of)

    2010-08-28

    We study the phenomenon of an electromagnetically induced phase grating in a double-dark state system of {sup 87}Rb atoms, the two closely placed lower fold levels of which are coupled by a weak microwave field. Owing to the existence of the weak microwave field, the efficiency of the phase grating is strikingly improved, and an efficiency of approximately 33% can be achieved. Under the action of the weak standing wave field, the high efficiency of the phase grating can be maintained by modulating the strength and detuning of the weak microwave field, increasing the strength of the standing wave field. (fast track communication)

  12. Diffraction by m-bonacci gratings

    Science.gov (United States)

    Monsoriu, Juan A.; Giménez, Marcos H.; Furlan, Walter D.; Barreiro, Juan C.; Saavedra, Genaro

    2015-11-01

    We present a simple diffraction experiment with m-bonacci gratings as a new interesting generalization of the Fibonacci ones. Diffraction by these non-conventional structures is proposed as a motivational strategy to introduce students to basic research activities. The Fraunhofer diffraction patterns are obtained with the standard equipment present in most undergraduate physics labs and are compared with those obtained with regular periodic gratings. We show that m-bonacci gratings produce discrete Fraunhofer patterns characterized by a set of diffraction peaks which positions are related to the concept of a generalized golden mean. A very good agreement is obtained between experimental and numerical results and the students’ feedback is discussed.

  13. Influence of grating thickness in low-contrast subwavelength grating concentrating lenses

    Science.gov (United States)

    Ye, Mao; Yi, Ya Sha

    2016-07-01

    Conventional subwavelength grating concentrating lenses are designed based on calculated phase overlap, wherein the phase change is fixed by the grating thickness, bar-width, and airgap, and therefore the focus. We found that certain concentration effects can still be maintained by changing the grating thickness with the same bar-widths and airgap dimensions. Following that, we discovered the existence of the grating thickness threshold; light concentration intensity spikes upon exceeding this limit. However, the light concentration property does not change continuously with respect to a steady increase in grating thickness. This observation indicates that there exists a concentration mode self-interference effect along the light propagation direction inside the gratings. Our results may provide guidance in designing and fabricating microlenses in a potentially more easy and controllable manner. Such approaches can be utilized in various integrated nanophotonics applications ranging from optical cavities and read/write heads to concentrating photovoltaics.

  14. New transfer matrix method for long-period fiber gratings with coupled multiple cladding modes

    Institute of Scientific and Technical Information of China (English)

    Guodong Wang; Yunjian Wang

    2011-01-01

    A new transfer matrix method for long-period fiber gratings with coupled multiple cladding modes is proposed and numerically characterized. The transmission spectra of uniform and non-uniform long-period fiber gratings are numerically characterized. The theoretical results excellently agree with the experimental measurements. Compared with commonly used methods, such as using the fourth-order adaptive step size control of the Runge-Kutta algorithm in solving the coupled mode equation, the new transfer matrix method exhibits a faster calculation speed.%@@ A new transfer matrix method for long-period fiber gratings with coupled multiple cladding modes is proposed and numerically characterized.The transmission spectra of uniform and non-uniform longperiod fiber gratings are numerically characterized.The theoretical results excellently agree with the experimental measurements.Compared with commonly used methods,such as using the fourth-order adaptive step size control of the Runge-Kutta algorithm in solving the coupled mode equation,the new transfer matrix method exhibits a faster calculation speed.

  15. Chandra Locates Mother Lode of Planetary Ore in Colliding Galaxies

    Science.gov (United States)

    2004-01-01

    NASA's Chandra X-ray Observatory has discovered rich deposits of neon, magnesium, and silicon in a pair of colliding galaxies known as The Antennae. When the clouds in which these elements are present cool, an exceptionally high number of stars with planets should form. These results may foreshadow the fate of the Milky Way and its future collision with the Andromeda Galaxy. "The amount of enrichment of elements in The Antennae is phenomenal," said Giuseppina Fabbiano of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. at a press conference at a meeting of the American Astronomical Society in Atlanta, Ga. "This must be due to a very high rate of supernova explosions in these colliding galaxies." Fabbiano is lead author of a paper on this discovery by a team of U.S. and U.K. scientists that will appear in an upcoming issue of The Astrophysical Journal Letters. When galaxies collide, direct hits between stars are extremely rare, but collisions between huge gas clouds in the galaxies can trigger a stellar baby boom. The most massive of these stars race through their evolution in a few million years and explode as supernovas. Heavy elements manufactured inside these stars are blown away by the explosions and enrich the surrounding gas for thousands of light years. "The amount of heavy elements supports earlier studies that indicate there was a very high rate of relatively recent supernovas, 30 times that of the Milky Way," according to collaborator Andreas Zezas of the CfA. Animation of Colliding Galaxies Animation of Colliding Galaxies The supernova violence also heats the gas to millions of degrees Celsius. This makes much of the matter in the clouds invisible to optical telescopes, but it can be observed by an X-ray telescope. Chandra data revealed for the first time regions of varying enrichment in the galaxies – in one cloud magnesium and silicon are 16 and 24 times as abundant as in the Sun. "These are the kinds of elements that

  16. Chandra Looks Over a Cosmic Four-Leaf Clover

    Science.gov (United States)

    2004-07-01

    A careful analysis of observations by NASA's Chandra X-ray Observatory of a rare quadruple quasar has uncovered evidence that possibly a single star in a foreground galaxy magnified X-rays coming from the quasar. This discovery gives astronomers a new and extremely precise probe of the gas flow around the supermassive black hole that powers the quasar. "If our interpretation is correct, then we are seeing details around this black hole that are 50,000 times smaller than either the Hubble Space Telescope or Chandra could see under ordinary circumstances," said George Chartas of Penn State University in University Park, and lead author of a recent article on the Cloverleaf quasar in The Astrophysical Journal. The Cloverleaf quasar is a single object about 11 billion light years from Earth that appears as four images produced by a process known as gravitational lensing. If one or more galaxies lie along the line of sight to a more distant quasar, the gravitational field of the intervening galaxies can bend and magnify the light from the quasar and produce multiple images of it. The four images of the Cloverleaf quasar have been produced by one or more intervening galaxies. Cloverleaf Quasar Chandra X-ray Image of the Cloverleaf quasar One of the images (A), in the Cloverleaf is brighter than the others in both optical and X-ray light. Chartas and his colleagues found the relative brightness of this image was greater in X-ray than in optical light. The X-rays from iron atoms were also enhanced relative to X-rays at lower energies. Since the amount of brightening due to gravitational lensing does not vary with the wavelength, this means that an additional object has magnified the X-rays. The increased magnification of the X-ray light can be explained by gravitational microlensing, an effect which has been used to search for compact stars and planets in our galaxy. Microlensing occurs when a star or a multiple star system passes in front of light from a background object

  17. Chandra's Find of Lonely Halo Raises Questions About Dark Matter

    Science.gov (United States)

    2004-10-01

    Dark matter continues to confound astronomers, as NASA's Chandra X-ray Observatory demonstrated with the detection of an extensive envelope of dark matter around an isolated elliptical galaxy. This discovery conflicts with optical data that suggest a dearth of dark matter around similar galaxies, and raises questions about how galaxies acquire and keep such dark matter halos. The observed galaxy, known as NGC 4555, is unusual in that it is a fairly large, elliptical galaxy that is not part of a group or cluster of galaxies. In a paper to be published in the November 1, 2004 issue of the Monthly Notices of the Royal Astronomical Society, Ewan O'Sullivan of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA and Trevor Ponman of the University of Birmingham, United Kingdom, use the Chandra data to show that the galaxy is embedded in a cloud of 10-million-degree-Celsius gas. X-ray/Optical Composite of NGC 4555 X-ray/Optical Composite of NGC 4555 This hot gas cloud has a diameter of about 400,000 light years, about twice that of the visible galaxy. An enormous envelope, or halo, of dark matter is needed to confine the hot cloud to the galaxy. The total mass of the dark matter halo is about ten times the combined mass of the stars in the galaxy, and 300 times the mass of the hot gas cloud. A growing body of evidence indicates that dark matter - which interacts with itself and "normal" matter only through gravity - is the dominant form of matter in the universe. According to the popular "cold dark matter" theory, dark matter consists of mysterious particles left over from the dense early universe that were moving slowly when galaxies and galaxy clusters began to form. "The observed properties of NGC 4555 confirm that elliptical galaxies can posses dark matter halos of their own, regardless of their environment," said O'Sullivan. "This raises an important question: what determines whether elliptical galaxies have dark matter halos?" DSS Optical Image of NGC

  18. Chandra Finds Surprising Black Hole Activity In Galaxy Cluster

    Science.gov (United States)

    2002-09-01

    Scientists at the Carnegie Observatories in Pasadena, California, have uncovered six times the expected number of active, supermassive black holes in a single viewing of a cluster of galaxies, a finding that has profound implications for theories as to how old galaxies fuel the growth of their central black holes. The finding suggests that voracious, central black holes might be as common in old, red galaxies as they are in younger, blue galaxies, a surprise to many astronomers. The team made this discovery with NASA'S Chandra X-ray Observatory. They also used Carnegie's 6.5-meter Walter Baade Telescope at the Las Campanas Observatory in Chile for follow-up optical observations. "This changes our view of galaxy clusters as the retirement homes for old and quiet black holes," said Dr. Paul Martini, lead author on a paper describing the results that appears in the September 10 issue of The Astrophysical Journal Letters. "The question now is, how do these black holes produce bright X-ray sources, similar to what we see from much younger galaxies?" Typical of the black hole phenomenon, the cores of these active galaxies are luminous in X-ray radiation. Yet, they are obscured, and thus essentially undetectable in the radio, infrared and optical wavebands. "X rays can penetrate obscuring gas and dust as easily as they penetrate the soft tissue of the human body to look for broken bones," said co-author Dr. Dan Kelson. "So, with Chandra, we can peer through the dust and we have found that even ancient galaxies with 10-billion-year-old stars can have central black holes still actively pulling in copious amounts of interstellar gas. This activity has simply been hidden from us all this time. This means these galaxies aren't over the hill after all and our theories need to be revised." Scientists say that supermassive black holes -- having the mass of millions to billions of suns squeezed into a region about the size of our Solar System -- are the engines in the cores of

  19. Chandra "Hears" A Black Hole For The First Time

    Science.gov (United States)

    2003-09-01

    NASA's Chandra X-ray Observatory detected sound waves, for the first time, from a super-massive black hole. The "note" is the deepest ever detected from an object in the universe. The tremendous amounts of energy carried by these sound waves may solve a longstanding problem in astrophysics. The black hole resides in the Perseus cluster, located 250 million light years from Earth. In 2002, astronomers obtained a deep Chandra observation that shows ripples in the gas filling the cluster. These ripples are evidence for sound waves that have traveled hundreds of thousands of light years away from the cluster's central black hole. perseus animation Illustration of Ripples in Perseus "We have observed the prodigious amounts of light and heat created by black holes, now we have detected the sound," said Andrew Fabian of the Institute of Astronomy (IoA) in Cambridge, England, and leader of the study. In musical terms, the pitch of the sound generated by the black hole translates into the note of B flat. But, a human would have no chance of hearing this cosmic performance, because the note is 57 octaves lower than middle-C (by comparison a typical piano contains only about seven octaves). At a frequency over a million, billion times deeper than the limits of human hearing, this is the deepest note ever detected from an object in the universe. "The Perseus sound waves are much more than just an interesting form of black hole acoustics," said Steve Allen, also of the IoA and a co-investigator in the research. "These sound waves may be the key in figuring out how galaxy clusters, the largest structures in the universe, grow," Allen said. For years astronomers have tried to understand why there is so much hot gas in galaxy clusters and so little cool gas. Hot gas glowing with X-rays should cool, and the dense central gas should cool the fastest. The pressure in this cool central gas should then fall, causing gas further out to sink in towards the galaxy, forming trillions of

  20. Silicon waveguide polarization rotation Bragg grating with phase shift section and sampled grating scheme

    Science.gov (United States)

    Okayama, Hideaki; Onawa, Yosuke; Shimura, Daisuke; Yaegashi, Hiroki; Sasaki, Hironori

    2016-08-01

    We describe a Bragg grating with a phase shift section and a sampled grating scheme that converts input polarization to orthogonal polarization. A very narrow polarization-independent wavelength peak can be generated by phase shift structures and polarization-independent multiple diffraction peaks by sampled gratings. The characteristics of the device were examined by transfer matrix and finite-difference time-domain methods.

  1. Access Platforms for Offshore Wind Turbines Using Gratings

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Rasmussen, Michael R.

    2008-01-01

    The paper deals with forces generated by a stationary jet on different types of gratings and a solid plate. The force reduction factors for the different gratings compared to the solid plate mainly depend on the porosity of the gratings, but the geometry of the grating is also of some importance........ The derived reduction factors are expected to be applicable to design of offshore wind turbine access platforms with gratings where slamming also is an important factor....

  2. Long period fiber gratings induced by mechanical resonance

    CERN Document Server

    Shahal, Shir; Duadi, Hamootal; Fridman, Moti

    2015-01-01

    We present a simple, and robust method for writing long period fiber gratings with low polarization dependent losses. Our method is based on utilizing mechanical vibrations of the tapered fiber while pooling it. Our method enables real-time tunability of the periodicity, efficiency and length of the grating. We also demonstrate complex grating by writing multiple gratings simultaneously. Finally, we utilized the formation of the gratings in different fiber diameters to investigate the Young's modulus of the fiber.

  3. Theory of photorefractive dynamic grating formulation

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The photorefractive holographic recording and two-beam coupling are both dynamic grating formulation process. The interference light intensity of the two coherent beams induces a phase grating though photo-induced refractive index variation and the phase grating changing the intensities of the two beams through beam-coupling take place at the same time. By solving simultaneously the band transport equations and wave-coupled equations, and using the light intensity modulation as the main variable, the analytic solution is obtained, which is valid for any light intensity modulation and constant light excitation efficiency. Here all the mechanics of drift, diffusion and photovoltaic effect are considered. The result shows that the modulation of the dynamic grating varies more slowly compared with that of the linear modulation approximation.

  4. Hydraulic Capacity of an ADA Compliant Street Drain Grate

    Energy Technology Data Exchange (ETDEWEB)

    Lottes, Steven A. [Argonne National Lab. (ANL), Argonne, IL (United States); Bojanowski, Cezary [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-01

    Resurfacing of urban roads with concurrent repairs and replacement of sections of curb and sidewalk may require pedestrian ramps that are compliant with the American Disabilities Act (ADA), and when street drains are in close proximity to the walkway, ADA compliant street grates may also be required. The Minnesota Department of Transportation ADA Operations Unit identified a foundry with an available grate that meets ADA requirements. Argonne National Laboratory’s Transportation Research and Analysis Computing Center used full scale three dimensional computational fluid dynamics to determine the performance of the ADA compliant grate and compared it to that of a standard vane grate. Analysis of a parametric set of cases was carried out, including variation in longitudinal, gutter, and cross street slopes and the water spread from the curb. The performance of the grates was characterized by the fraction of the total volume flow approaching the grate from the upstream that was captured by the grate and diverted into the catch basin. The fraction of the total flow entering over the grate from the side and the fraction of flow directly over a grate diverted into the catch basin were also quantities of interest that aid in understanding the differences in performance of the grates. The ADA compliant grate performance lagged that of the vane grate, increasingly so as upstream Reynolds number increased. The major factor leading to the performance difference between the two grates was the fraction of flow directly over the grates that is captured by the grates.

  5. Quasar Rain: Chandra and the Inner Structure of AGN

    Science.gov (United States)

    Elvis, Martin

    2014-11-01

    Chandra observations of X-ray eclipses (XRE) and Warm Absorbers (WA) in quasars produce a self-consistent view of the X-ray source and of the broad emission line region (BELR). XREs limit the size of the X-ray source and enable topographic imaging of both continuum and relativistic Fe-K. XREs imply the existence of >10(8) discrete absorbing clouds with properties consistent with being BELR clouds. These clouds are being ablated away in months and must be constantly renewed. Both eclipsing and BELR clouds have the same properties as the low ionization phase of the WAs found in LETG/HETG spectra. Hence BELR clouds must be continually condensing out of the quasar disk wind in a mist. If the clouds have not reached escape velocity they will fall toward the black hole as a quasar rain.

  6. Chandra LETG Observations of Supernova Remnant 1987A

    CERN Document Server

    Zhekov, S A; Burrows, D N; McCray, R; Park, S; Borkowski, Kazimierz J.; Burrows, David N.; Cray, Richard Mc; Park, Sangwook; Zhekov, Svetozar A.

    2006-01-01

    We discuss the results from deep Chandra LETG observations of the supernova remnant 1987A (SNR 1987A). We find that a distribution of shocks, spanning the same range of velocities (from 300 to 1700 km/s) as deduced in the first part of our analysis (Zhekov et al. 2005, ApJL, 628, L127), can account for the entire X-ray spectrum of this object. The post-shock temperature distribution is bimodal, peaking at kT 0.5 and 3 keV. Abundances inferred from the X-ray spectrum have values similar to those for the inner circumstellar ring, except that the abundances of nitrogen and oxygen are approximately a factor of two lower than those inferred from the optical/UV spectrum. The velocity of the X-ray emitting plasma has decreased since 1999, apparently because the blast wave has entered the main body of the inner circumstellar ring.

  7. Polarization-resolved sensing with tilted fiber Bragg gratings: theory and limits of detection

    CERN Document Server

    Bialiayeu, Aliaksandr; Albert, Jacques

    2015-01-01

    Polarization based sensing with tilted fiber Bragg grating (TFBG) sensors is analysed theoretically by two alternative approaches. The first method is based on tracking the grating transmission for two orthogonal states of linear polarized light that are extracted from the measured Jones matrix or Stokes vectors of the TFBG transmission spectra. The second method is based on the measurements along the system principle axes and polarization dependent loss (PDL) parameter, also calculated from measured data. It is shown that the frequent crossing of the Jones matrix eigenvalues as a function of wavelength leads to a non-physical interchange of the calculated principal axes; a method to remove this unwanted mathematical artefact and to restore the order of the system eigenvalues and the corresponding principal axes is provided. A comparison of the two approaches reveals that the PDL method provides a smaller standard deviation and therefore lower limit of detection in refractometric sensing. Furthermore, the pol...

  8. Theoretical analysis of ridge gratings for long-range surface plasmon polaritons

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Bozhevolnyi, Sergey I.; Boltasseva, Alexandra

    2006-01-01

    Optical properties of ridge gratings for long-range surface plasmon polaritons (LRSPPs) are analyzed theoretically in a two-dimensional configuration via the Lippmann-Schwinger integral equation method. LRSPPs being supported by a thin planar gold film embedded in dielectric are considered...... to be scattered by an array of equidistant gold ridges on each side of the film designed for in-plane Bragg scattering of LRSPPs at the wavelength ~1550 nm. Out-of-plane scattering (OUPS), LRSPP transmission, reflection, and absorption are investigated with respect to the wavelength, the height of the ridges......, and the length of the grating. Particular attention is paid to the fraction of the LRSPP power lost due to the OUPS. We find an asymmetry in the OUPS spectra in the vicinity of the band gap and relate this asymmetry to that observed in the transmission spectra. It is found that in order to maximize a reflection...

  9. A novel oil level monitoring sensor based on string tilted fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    JIANG Qi

    2011-01-01

    In this paper, we present a novel oil level monitoring sensor based on string tilted fiber Bragg grating (TFBG). The mea- surement range and sensitivity of oil level monitoring can be modulated via changing the length and number of string tilted fiber gratings. The transmission spectrum of string TFBGs immersed in oil changes obviously with the oil level variation. Experiments are conducted on three 2 crn-length serial TFBGs with the same tilted angle of 10°. A sensitivity of 3.28 dB/cm in the string TFBG sensor is achieved with good linearity by means of TFBG spectrum characteristic with peak-low value. The cladding mode transmission power and the amplitude of high order cladding mode resonance are nearly linear to the oil level variation. This kind of sensor is insensitive to temperature and attributed to be employed in extremely harsh environ- ment oil monitoring.

  10. Group velocity dispersion and polarization mode dispersion compensation by high-birefringence linearly chirped fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Muguang Wang(王目光); Tangjun Li(李唐军); Shuisheng Jian(简水生)

    2004-01-01

    A high-birefringence linearly chirped fiber Bragg grating (FBG) is written into a polarization-maintaining photosensitive fiber by ultraviolet (UV) beam through a linearly chirped phase mask. Its performance as group velocity dispersion (GVD) and polarization mode dispersion (PMD) compensator is demonstrated in short pulse fiber optical transmission systems.

  11. Searching for bulk motions in the ICM of massive, merging clusters with Chandra CCD data

    CERN Document Server

    Liu, Ang; Tozzi, Paolo; Zhu, Zong-Hong

    2016-01-01

    We search for bulk motions in the Intra Cluster Medium (ICM) of massive clusters showing evidence of an ongoing or a recent major merger, with spatially resolved spectroscopy in {\\sl Chandra} CCD data. We identify a sample of 6 merging clusters with >150 ks {\\sl Chandra} exposure in the redshift range 0.1 1000$ km/s in the ICM of massive merging clusters at 0.1 < z < 0.3. Despite the CCD spectral resolution is not sufficient for a detailed analysis of the ICM dynamics, {\\sl Chandra} CCD data constitute a key diagnostic tool complementary to X-ray bolometers onboard future X-ray missions.

  12. Chandra resolves the T Tauri binary system RW Aur

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Stephen L. [CASA, University of Colorado, Boulder, CO 80309-0389 (United States); Güdel, Manuel, E-mail: stephen.skinner@colorado.edu, E-mail: manuel.guedel@univie.ac.at [Department of Astrophysics, University of Vienna, Türkenschanzstr. 17, A-1180 Vienna (Austria)

    2014-06-20

    RW Aur is a multiple T Tauri system consisting of an early-K type primary (A) and a K5 companion (B) at a separation of 1.''4. RW Aur A drives a bipolar optical jet that is well characterized optically. We present results of a sensitive Chandra observation whose primary objective was to search for evidence of soft extended X-ray emission along the jet, as has been seen for a few other nearby T Tauri stars. The binary is clearly resolved by Chandra and both stars are detected as X-ray sources. The X-ray spectra of both stars reveal evidence for cool and hot plasma. Surprisingly, the X-ray luminosity of the less-massive secondary is at least twice that of the primary and is variable. The disparity is attributed to the primary whose X-ray luminosity is at the low end of the range for classical T Tauri stars of similar mass based on established correlations. Deconvolved soft-band images show evidence for slight outward elongation of the source structure of RW Aur A along the blueshifted jet axis inside the central arcsecond. In addition, a faint X-ray emission peak is present on the redshifted axis at an offset of 1.''2 ± 0.''2 from the star. Deprojected jet speeds determined from previous optical studies are too low to explain this faint emission peak as shock-heated jet plasma. Thus, unless flow speeds in the redshifted jet have been underestimated, other mechanisms such as magnetic jet heating may be involved.

  13. Automated classification of Chandra X-ray sources

    Science.gov (United States)

    Brehm, Derek; Kargaltsev, O.; Rangelov, B.; Volkov, I.; Pavlov, G. G.

    2014-01-01

    With the advent of the latest generation X-ray telescopes there has been a major influx of data associated with the detection of hundreds of thousands X-ray sources. As one can rarely tell a source type from its X-ray properties alone, the full potential of the X-ray catalogs can only be unlocked by correlating multiwavelength (MW) properties via cross-identification with other surveys. However, one would spend an enormous amount of time classifying these objects by their physical nature if the classification was to be done on a source-by-source basis by humans. Therefore, we are using a supervised learning algorithm to classify sources detected by the Chandra X-ray Observatory. The classifications are based on a training dataset which currently includes about 7,000 X-ray sources of known nature (main sequence stars, Wolf-Rayet stars, young stars, active galactic nuclei, low mass X-ray binaries, high mass x-ray binaries, and neutron stars). For each source, the training dataset includes up to 24 multiwavelength properties. The efficiency and accuracy of the classification is verified by dividing the training dataset in two and performing cross-validation. The results are also inspected by plotting source properties in 2D slices of the parameter space. As an application of our automated procedure we classified unidentified sources in the supernova remnant (SNR) G352.7-0.1, in the field of HESS J1809-193, and in part of the Chandra Source Catalog 1.0. We present the results of the verification tests and the classification results. This research was partially supported by NASA/SAO grant AR3-14017X.

  14. Dynamic optical coupled system employing Dammann gratings

    Science.gov (United States)

    Di, Caihui; Zhou, Changhe; Ru, Huayi

    2004-10-01

    With the increasing of the number of users in optical fiber communications, fiber-to-home project has a larger market value. Then the need of dynamic optical couplers, especially of N broad-band couplers, becomes greater. Though some advanced fiber fusion techniques have been developed, they still have many shortcomings. In this paper we propose a dynamic optical coupled system employing even-numbered Dammann gratings, which have the characteristic that the phase distribution in the first half-period accurately equals to that in the second-period with π phase inversion. In our experiment, we divide a conventional even-numbered Dammann grating into two identical gratings. The system can achieve the beam splitter and combiner as the switch between them according to the relative shift between two complementary gratings. When there is no shift between the gratings, the demonstrated 1×8 dynamic optical coupler achieves good uniformity of 0.06 and insertion loss of around 10.8 dB for each channel as a splitter. When the two gratings have an accurate shift of a half-period between them, our system has a low insertion loss of 0.46 dB as a combiner at a wavelength of 1550 nm.

  15. NASA'S Chandra Finds New Evidence on Origin of Supernovas

    Science.gov (United States)

    2011-04-01

    CAMBRIDGE, Ma. -- Astronomers may now know the cause of an historic supernova explosion that is an important type of object for investigating dark energy in the universe. The discovery, made using NASA's Chandra X-ray Observatory, also provides strong evidence that a star can survive the explosive impact generated when a companion star goes supernova. The new study examined the remnant of a supernova observed by the Danish astronomer Tycho Brahe in 1572. The object, dubbed Tycho for short, was formed by a Type Ia supernova, a category of stellar explosion useful in measuring astronomical distances because of their reliable brightness. Type Ia supernovas have been used to determine that the universe is expanding at an accelerating rate, an effect attributed to the prevalence of an invisible, repulsive force throughout space called dark energy. A team of researchers analyzed a deep Chandra observation of Tycho and found an arc of X-ray emission in the supernova remnant. Evidence supports the conclusion that a shock wave created the arc when a white dwarf exploded and blew material off the surface of a nearby companion star. "There has been a long-standing question about what causes Type Ia supernovas," said Fangjun Lu of the Institute of High Energy Physics, Chinese Academy of Sciences in Beijing. "Because they are used as steady beacons of light across vast distances, it is critical to understand what triggers them." One popular scenario for Type Ia supernovas involves the merger of two white dwarfs. In this case, no companion star or evidence for material blasted off a companion should exist. In the other main competing theory, a white dwarf pulls material from a "normal," or sun-like, companion star until a thermonuclear explosion occurs. Both scenarios may actually occur under different conditions, but the latest Chandra result from Tycho supports the latter one. n addition, the Tycho study seems to show the remarkable resiliency of stars, as the supernova

  16. Chandra Finds Well-Established Black Holes In Distant Quasars

    Science.gov (United States)

    2002-03-01

    Pushing further back toward the first generation of objects to form in the universe, NASA's Chandra X-ray Observatory has observed the three most distant known quasars and found them to be prodigious producers of X-rays. This indicates that the supermassive black holes powering them were already in place when the Universe was only about one billion years old. "Chandra's superb sensitivity has allowed the detection of X-rays from the dawn of the modern universe, when the first massive black holes and galaxies were forming," said Niel Brandt of Penn State University, leader of one the teams involved. "These results indicate that future X-ray surveys should be able to detect the first black holes to form in the Universe." The three quasars were recently discovered at optical wavelengths by the Sloan Digital Sky Survey and are 13 billion light years from Earth, making them the most distant known quasars. The X-rays Chandra detected were emitted when the universe was only a billion years old, about 7 percent of the present age of the Universe. Since X-rays reveal conditions in the immediate vicinity of supermassive black holes, Brandt proposed that Chandra look at these objects in three snapshots of about two hours each to see if they were different from their older counterparts. The observations on January 29, 2002 were made public immediately and the four different teams quickly went to work on them. Brandt's team concluded that the quasars looked similar to ones that were at least twice as old, so the conditions around the central black hole had not changed much in that time, contrary to some theoretical expectations. A team led by Smita Mathur of Ohio State University reached a similar conclusion. "These young quasars do not appear to be any different from their older cousins, based upon our current understanding and assumptions," said Mathur. "Perhaps the most remarkable thing about them may be that they are so absolutely unremarkable." Jill Bechtold of the

  17. Inverse-Gaussian-Apodized Fiber Bragg Grating for Dual Wavelength Lasing

    CERN Document Server

    Lin, Bo; Tjin, Swee Chuan; Tang, Dingyuan; Hao, Jianzhong; Tay, Chia Meng; Liang, Sheng

    2010-01-01

    A fiber Bragg grating (FBG) with an inverse-Gaussian apodization function is proposed and fabricated. It is shown that such a FBG possesses easily controllable dual-wavelength narrow transmission peaks. Incorporating such a FBG filter in a fiber laser with a linear cavity, stable dual-wavelength emission with 0.146 nm wavelength spacing is obtained. It provides a simple and low cost approach of achieving the dual-wavelength fiber laser operation.

  18. Large area fabrication of plasmonic nanoparticle grating structure by conventional scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.; Srivastava, A. K. [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advance Technology, Indore-452013 (India); Mukharjee, C. [Mechanical & Optical Support Section, Raja Ramanna Centre for Advance Technology, Indore 452013 (India)

    2015-06-24

    Plasmonic nanoparticle grating (PNG) structure of different periods has been fabricated by electron beam lithography using silver halide based transmission electron microscope film as a substrate. Conventional scanning electron microscope is used as a fabrication tool for electron beam lithography. Optical microscope and energy dispersive spectroscopy (EDS) have been used for its morphological and elemental characterization. Optical characterization is performed by UV-Vis absorption spectroscopic technique.

  19. Optical nonlinearity of organic dyes as studied by Z-scan and transient grating techniques

    Indian Academy of Sciences (India)

    Umakanta Tripathy; R Justin Rajesh; Prem B Bisht; A Subrahamanyam

    2002-12-01

    The excited state absorption cross-section of 5,5′-dichloro-11-diphenylamino- 3,3′-diethyl-10,12-ethylinethiatricarbocyanine perchlorate (IR140) have been measured by using a single beam transmission technique. Z-scan experiments have been used to find out a few nonlinear parameters. The excited state relaxation times have also been measured by using laser induced transient grating (LITG) technique.

  20. Magneto-Optic Fiber Bragg Gratings with Application to High-Resolution Magnetic Field Sensors

    Institute of Scientific and Technical Information of China (English)

    Bao-Jian Wu; Ying Yang; Kun Qiu

    2008-01-01

    Magneto-optic fiber Bragg gratings (MFBG) based on magneto-optic materials have a lot of potential applications for sensing and optical signal processing. The transmission and reflection spectra of guided optical waves in the MFBG are investigated. According to the sensitivity of MFBG spectral lines to the magneto-optic coupling intensity varying with applied magnetic field, a novel magnetic field sensor of high-resolution up to 0.01 nm/(kA/m) is predicted.

  1. Integrated high-order surface diffraction gratings for diode lasers

    Science.gov (United States)

    Zolotarev, V. V.; Leshko, A. Yu; Pikhtin, N. A.; Slipchenko, S. O.; Sokolova, Z. N.; Lubyanskiy, Ya V.; Voronkova, N. V.; Tarasov, I. S.

    2015-12-01

    High-order surface diffraction gratings acting as a distributed Bragg reflector (DBR) in mesa stripe semiconductor lasers (λ = 1030 nm) have been studied theoretically and experimentally. Higher order interfering radiation modes (IRMs), which propagate off the plane of the waveguide, have been shown to have a crucial effect on the reflection and transmission spectra of the DBR. The decrease in the reflectivity of the DBR in response to the increase in the diffraction efficiency of these modes may reach 80% and more. According to theoretical analysis results, the intensity of the higher order IRMs is determined by the geometry of the DBR groove profile. Experimental data demonstrate that the noncavity modes are responsible for parasitic light leakage losses in the laser cavity. It has been shown that, in the case of nonoptimal geometry of the grating groove profile, the overall external differential quantum efficiency of the parasitic laser emission may exceed 45%, which is more than half of the laser output power. The optimal geometry of the DBR groove profile is trapezoidal, with the smallest possible lower base. Experimental evidence has been presented that this geometry considerably reduces the power of the higher order IRMs and minimises the parasitic light leakage loss.

  2. The grating and filter wheels for the JWST NIRSpec instrument

    Science.gov (United States)

    Weidlich, K.; Sedlacek, M.; Fischer, M.; Trunz, M.; Ellenrieder, M.; Lemke, D.; Krause, O.; Hofferbert, R.; Grözinger, U.; Königsreiter, G.; Neugebauer, C.

    2006-06-01

    The Near-Infrared Spectrograph (NIRSpec) onboard the James Webb Space Telescope can be reconfigured in space for astronomical observation in a range of filter bands as well as spectral resolutions. This will be achieved using a Filter wheel (FWA) which carries 7 transmission filters and a Grating wheel (GWA) which carries six gratings and one prism. The large temperature shift between warm launch and cryogenic operation (30K) and high launch vibration loads on the one hand side and accurate positioning capability and minimum deformation of optical components on the other hand side must be consolidated into a single mechanical design which will be achieved using space-proven concepts derived from the successful ISO filter wheel mechanisms which were manufactured and tested by Carl Zeiss. Carl Zeiss Optronics has been selected by Astrium GmbH for the implementation of both NIRSpec wheel mechanisms. Austrian Aerospace and Max-Planck-Institut fur Astronomie Heidelberg (MPIA) will contribute major work shares to the project. The project was started in October 2005 and the preliminary designs have been finalized recently. Critical performance parameters are properly allocated to respective hardware components, procurements of long-lead items have been initiated and breadboard tests have started. This paper presents an overview of the mechanism designs, discusses its properties and the approach for component level tests.

  3. Quantum-dot-array diffraction grating with single order diffraction property for soft x-ray region

    International Nuclear Information System (INIS)

    A gold transmission grating is used routinely to disperse the x-ray spectrum at the Z soft x-ray facility to measure the spectrum and temporal history of the absolute soft x-ray power emitted from z-pinch and hohlraum radiation sources. A quantum-dot-array diffraction grating (QDADG) of 250 lines/mm for soft x-ray is designed and fabricated for the first time according to the principle of binary sinusoidal transmission grating. The diffraction efficiencies of the grating are measured in the 150-300 eV photon energy range on the Beamline 3W1B of Beijing Synchrotron Radiation Facility. This article describes the basic concept and calibration techniques and presents calibration results. It is shown that the 250 lines/mm QDADG can be used to disperse light without higher-order diffractions in soft x-ray range, and the diffraction efficiencies of this grating are nearly constant (about 25%), which is beneficial in the spectrum analysis.

  4. Quantum-dot-array diffraction grating with single order diffraction property for soft x-ray region

    Science.gov (United States)

    Kuang, Longyu; Wang, Chuanke; Wang, Zhebin; Cao, Leifeng; Zhu, Xiaoli; Xie, Changqing; Liu, Shenye; Ding, Yongkun

    2010-07-01

    A gold transmission grating is used routinely to disperse the x-ray spectrum at the Z soft x-ray facility to measure the spectrum and temporal history of the absolute soft x-ray power emitted from z-pinch and hohlraum radiation sources. A quantum-dot-array diffraction grating (QDADG) of 250 lines/mm for soft x-ray is designed and fabricated for the first time according to the principle of binary sinusoidal transmission grating. The diffraction efficiencies of the grating are measured in the 150-300 eV photon energy range on the Beamline 3W1B of Beijing Synchrotron Radiation Facility. This article describes the basic concept and calibration techniques and presents calibration results. It is shown that the 250 lines/mm QDADG can be used to disperse light without higher-order diffractions in soft x-ray range, and the diffraction efficiencies of this grating are nearly constant (about 25%), which is beneficial in the spectrum analysis.

  5. A novel single-order diffraction grating: Random position rectangle grating

    Science.gov (United States)

    Zuhua, Yang; Qiangqiang, Zhang; Jing, Wang; Quanping, Fan; Yuwei, Liu; Lai, Wei; Leifeng, Cao

    2016-05-01

    Spectral diagnosis of radiation from laser plasma interaction and monochromation of radiation source are hot and important topics recently. Grating is one of the primary optical elements to do this job. Although easy to fabricate, traditional diffraction grating suffers from multi-order diffraction contamination. On the other hand, sinusoidal amplitude grating has the nonharmonic diffraction property, but it is too difficult to fabricate, especially for x-ray application. A novel nonharmonic diffraction grating named random position rectangle grating (RPRG) is proposed in this paper. Theoretical analysis and experiment results show that the RPRG is both higher order diffraction suppressing and not difficult to fabricate. Additionally, it is highly efficient; its first order absolute theoretical diffraction efficiency reaches 4.1%. Our result shows that RPRG is a novel tool for radiation diagnosis and monochromation. Project supported by the National Natural Science Foundation of China (Grant No. 11375160) and the National Science Instruments Major Project of China (Grant No. 2012YQ130125).

  6. Trends and future of fiber Bragg grating sensing technologies: tailored draw tower gratings (DTGs)

    Science.gov (United States)

    Lindner, E.; Hartung, A.; Hoh, D.; Chojetzki, C.; Schuster, K.; Bierlich, J.; Rothhardt, M.

    2014-05-01

    Today fiber Bragg gratings are commonly used in sensing technology as well as in telecommunications. Numerous requirements must be satisfied for their application as a sensor such as the number of sensors per system, the measurement resolution and repeatability, the sensor reusability as well as the sensor costs. In addition current challenges need to be met in the near future for sensing fibers to keep and extend their marketability such as the suitability for sterilization, hydrogen darkening or the separation of strain and temperature (or pressure and temperature). In this contribution we will give an outlook about trends and future of the fiber Bragg gratings in sensing technologies. Specifically, we will discuss how the use of draw tower grating technology enables the production of tailored Bragg grating sensing fibers, and we will present a method of separating strain and temperature by the use of a single Bragg grating only, avoiding the need for additional sensors to realize the commonly applied temperature compensation.

  7. Astronomer R.G. Chandra: In the Light of His Anglo-American Connection

    Science.gov (United States)

    Ray, Saibal; Nath Biswas, Sudhindra; Mukhopadhyay, Utpal

    2014-09-01

    In the present paper we have presented some documents to reveal the longstanding relationship of Indian amateur astronomer R.G. Chandra with the British Astronomical Association and American Association of Variable Star Observers.

  8. The Making of the Chandra X-ray Observatory: the Project Scientist's Perspective

    OpenAIRE

    Weisskopf, Martin C.

    2010-01-01

    The history of the development of the Chandra X-Ray Observatory is reviewed from a personal perspective. This review is necessarily biased and limited by space because it attempts to cover a time span approaching five decades.

  9. Femtosecond soliton diode on heterojunction Bragg-grating structure

    CERN Document Server

    Deng, Zhigui; Li, Hongji; Fu, Shenhe; Liu, Yikun; Xiang, Ying; Li, Yongyao

    2016-01-01

    We numerically propose a scheme for realizing an all-optical femtosecond soliton diode based on a tailored heterojunction Bragg grating, which is designed by two spatially asymmetric chirped cholesteric liquid crystals. Our simulations demonstrate that with the consideration of optical nonlinearity, not only the femtosecond diode effect with nonreciprocal transmission ratio up to 120 can be achieved, but also the optical pulse evolving into soliton which maintains its shape during propagation through the sample is observed. Further, the influence of pulse width and the carrier wavelength to the femtosecond diode effect is also discussed in detail. Our demonstrations might suggest a new direction for experimentally realizing the femtosecond soliton diode based on the cholesteric liquid crystals.

  10. Wide band polarizer with suspended germanium resonant grating

    Institute of Scientific and Technical Information of China (English)

    Wugang Cao; Jianyong Ma; Changhe Zhou

    2012-01-01

    An ultra broad band polarizer that operates in the telecommunication wavelength band is proposed.This device,which consists of a single suspended germanium resonant grating layer,is designed using the inverse mathematical method and the rigorous vector diffraction theory.Calculated results indicate that the ultra broad band polarizer exhibits extremely high reflection (R > 99%) for TE polarization light and high transmission (T > 99%) for TM polarization at the wavelength range greater than 300 nm,and it has an extinction ratio of approximately 1 000 at the 1 550-nm central wavelength.The results of the rigorous coupled wave analysis indicate that the extremely wide band property of the TE polarization is caused by the excitation of strong modulation guided modes in the design wavelength range.

  11. NASA'S Chandra Finds Superfluid in Neutron Star's Core

    Science.gov (United States)

    2011-02-01

    NASA's Chandra X-ray Observatory has discovered the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the core of a neutron star. Superfluids created in laboratories on Earth exhibit remarkable properties, such as the ability to climb upward and escape airtight containers. The finding has important implications for understanding nuclear interactions in matter at the highest known densities. Neutron stars contain the densest known matter that is directly observable. One teaspoon of neutron star material weighs six billion tons. The pressure in the star's core is so high that most of the charged particles, electrons and protons, merge resulting in a star composed mostly of uncharged particles called neutrons. Two independent research teams studied the supernova remnant Cassiopeia A, or Cas A for short, the remains of a massive star 11,000 light years away that would have appeared to explode about 330 years ago as observed from Earth. Chandra data found a rapid decline in the temperature of the ultra-dense neutron star that remained after the supernova, showing that it had cooled by about four percent over a 10-year period. "This drop in temperature, although it sounds small, was really dramatic and surprising to see," said Dany Page of the National Autonomous University in Mexico, leader of a team with a paper published in the February 25, 2011 issue of the journal Physical Review Letters. "This means that something unusual is happening within this neutron star." Superfluids containing charged particles are also superconductors, meaning they act as perfect electrical conductors and never lose energy. The new results strongly suggest that the remaining protons in the star's core are in a superfluid state and, because they carry a charge, also form a superconductor. "The rapid cooling in Cas A's neutron star, seen with Chandra, is the first direct evidence that the cores of these neutron stars are, in fact, made of superfluid and

  12. Using ACIS on the Chandra X-ray Observatory as a particle radiation monitor

    OpenAIRE

    Grant, C. E.; LaMarr, B.; Bautz, M.W.; O'Dell, S. L.

    2010-01-01

    The Advanced CCD Imaging Spectrometer (ACIS) is one of two focal-plane instruments on the Chandra X-ray Observatory. During initial radiation-belt passes, the exposed ACIS suffered significant radiation damage from trapped soft protons scattering off the x-ray telescope's mirrors. The primary effect of this damage was to increase the charge-transfer inefficiency (CTI) of the ACIS 8 front-illuminated CCDs. Subsequently, the Chandra team implemented procedures to remove the ACIS from the telesc...

  13. Double optical bistability and its application in nonlinear chalcogenide-fiber Bragg gratings

    International Nuclear Information System (INIS)

    We study the continuous wave (CW) nonlinear transmission characteristics of chalcogenide-fiber Bragg gratings (c-FBGs). The set of Cubic quintic septic nonlinear coupled mode equations (CQSNLCMEs) is derived analytically to govern nonlinear wave propagation in c-FBGs by counting until seventh-order nonlinearity in chalcogenide glass. Double-optical bistability is observed in the CW nonlinear transmission characteristics of π phase-shifted c-FBG. Based on unstable state principle in the hysteresis, all-optical transistor operation is shown as a prominent application of optical bistability in such device

  14. Resolving galaxy cluster gas properties at z~1 with XMM-Newton and Chandra

    CERN Document Server

    Bartalucci, I; Pratt, G W; Démoclès, J; van der Burg, R F J; Mazzotta, P

    2016-01-01

    We present a pilot X-ray study of the five most massive ($M_{500}>5 \\times 10^{14} M_{\\odot}$), distant (z~1), galaxy clusters detected via the Sunyaev-Zeldovich effect. We optimally combine XMM-Newton and Chandra X-ray observations by leveraging the throughput of XMM to obtain spatially-resolved spectroscopy, and the spatial resolution of Chandra to probe the bright inner parts and to detect embedded point sources. Capitalising on the excellent agreement in flux-related measurements, we present a new method to derive the density profiles, constrained in the centre by Chandra and in the outskirts by XMM. We show that the Chandra-XMM combination is fundamental for morphological analysis at these redshifts, the Chandra resolution being required to remove point source contamination, and the XMM sensitivity allowing higher significance detection of faint substructures. The sample is dominated by dynamically disturbed objects. We use the combined Chandra-XMM density profiles and spatially-resolved temperature prof...

  15. Fabrication of grating-like polystyrene latex monolayer structure as three-dimensional calibration standards for scanning probe microscope

    Institute of Scientific and Technical Information of China (English)

    Zhu Guo-Dong; Zeng Zhi-Gang; Guo Zhang; Du Qiang-Guo; Yan Xue-Jian

    2009-01-01

    This paper illuminates the preparation of grating-like polystyrene latex monolayer structure, which can minimize the effects of the size deviation of spheres and the defect transfer on the accuracy as calibration samples for micro-scopes. The latex films are grown on freshly cleaved mica substrates by vertical deposition method. The concentration dependence of the structure and the topography of latex films is characterized by optical microscope, ultraviolet-visible transmission spectrum and scanning probe microscope. The origination of such a grating-like structure is also discussed.

  16. Diffraction efficiency improvement in high spatial frequency holographic gratings stored in PVA/AA photopolymers: several ACPA concentrations

    International Nuclear Information System (INIS)

    High spatial frequency in holographic gratings is difficult to obtain due to limitations of the recording material. In this paper, the results obtained after storing holographic transmission gratings with a spatial frequency of 2656 lines/mm in a material based on polyvinyl alcohol and acrylamide (PVA/AA) are presented. A chain transfer agent, 4, 4′-azobis (4-cyanopentanoic acid) (ACPA) was incorporated in the composition of the material to improve the response of the material at a high spatial frequency. Different concentrations of ACPA were used in order to find the optimal concentration giving maximum diffraction efficiency for high spatial frequencies. (paper)

  17. Ring fiber resonators based on fused-fiber grating add-drop filters:application to resonator coupling

    OpenAIRE

    Choi, John M.; Lee, Reginald K.; Yariv, Amnon

    2002-01-01

    We introduce a fiber ring optical resonator based on adiabatic fused-fiber grating couplers. The coupling of a through fiber to the resonator is controlled by the strength of the fiber Bragg gratings. By using two of these couplers and incorporating erbium-doped (ED) fiber in the ring, we control the internal loss of the ring by pumping the ED fiber. The transmission spectra of the through port and the drop port of a four-port configuration, a ring coupled to two waveguides, are measured. We ...

  18. Optically switchable, polarization-independent holographic polymer dispersed liquid crystal (H-PDLC) gratings

    Science.gov (United States)

    Hsiao, V. K. S.; Chang, W.-T.

    2010-09-01

    An optically switchable, polarization-independent holographic polymer dispersed liquid crystal (H-PDLC) transmission grating is demonstrated by adding azobenzene-LC and chiral molecules into the H-PDLC formulation. The optical switchable mechanism is from the trans-cis photoisomerization of the doped azobenzene-LC, which modulates the refractive index of the LC rich area. The dependence of the diffraction efficiency of the H-DPLC grating without chiral molecules on light polarization suggests that the orientation of LC directors within the droplet is ellipsoidal and uniaxial. However, the addition of chiral molecules into the H-PDLC formulation helps the formation of isotropic and non-uniaxial LC directors within the droplets. The polarization properties of the grating are investigated and analyzed by the coupled and modified coupled wave theory with a model of sinusoidal dielectric modulation. The results show that the addition of chiral molecules changes the LC phase from nematic to chiral-nematic, where the grating efficiency, which is modulated by the photoinduced phase transition, is independent of the polarization of incident light. Our findings may help improve optical systems that utilize non-polarized light.

  19. Parametric study of the reflective periodic grating for in-plane displacement measurement using optical fibers.

    Science.gov (United States)

    Lee, Yeon-Gwan; Kim, Dae-Hyun; Kim, Chun-Gon

    2012-01-01

    This paper presents a technique for a simple sensing principle that can be used for the measurement of displacement. The proposed sensor head is composed of a reflective grating panel and an optical fiber as a transceiver. The simplified layout contributes to resolving the issues of space restraints during installation and complex cabling problems in transmission fiber optic sensors. In order to verify the effectiveness of the proposed technique, it is important to obtain the sinusoidal signal reflected from the grating for reasonable phase tracking. In the numerical analysis, a real wave based optical beam model is proposed for the extraction of predicted signal according to the grating width and ratio of reflection bar width to spacing. The grating pattern design to obtain a sine wave reflected sensor signal was determined within an R-square value of 0.98 after sine curve fitting analysis. Consequently, the proposed sensor principle achieved the in-plane displacement measurement with a maximum accuracy error of 5.34 μm. PMID:22666030

  20. Parametric Study of the Reflective Periodic Grating for In-Plane Displacement Measurement Using Optical Fibers

    Directory of Open Access Journals (Sweden)

    Chun-Gon Kim

    2012-03-01

    Full Text Available This paper presents a technique for a simple sensing principle that can be used for the measurement of displacement. The proposed sensor head is composed of a reflective grating panel and an optical fiber as a transceiver. The simplified layout contributes to resolving the issues of space restraints during installation and complex cabling problems in transmission fiber optic sensors. In order to verify the effectiveness of the proposed technique, it is important to obtain the sinusoidal signal reflected from the grating for reasonable phase tracking. In the numerical analysis, a real wave based optical beam model is proposed for the extraction of predicted signal according to the grating width and ratio of reflection bar width to spacing. The grating pattern design to obtain a sine wave reflected sensor signal was determined within an R-square value of 0.98 after sine curve fitting analysis. Consequently, the proposed sensor principle achieved the in-plane displacement measurement with a maximum accuracy error of 5.34 µm.