Sample records for wavemeters

  1. A Novel High-Precision Laser Wavemeter

    Institute of Scientific and Technical Information of China (English)

    WANG Li-qiang; ZHENG Hon-gxing


    The wavemeter can measure a wavelength of a tuned laser and an unknown laser. Due to the Doppler shift, the wavemeter operates and establishes coherent interference fringes on the detectors according to the Michelson interference principle. The electronic signals of the reference laser and an unknown laser both are multiplied frequency by PLL (Phase-Locked Loop) unit so as to enhance the resolutions of the wavemeter. PLL unit consists of NE564 and 74LS193.The movable reflector of the wavemeter is driven by a voice-coin motor. The closed loop feedback design can ensure the movable reflector to move in constant speed all the time. Experiment results show that precision of this wavemeter is super to 1×10-6, approaching to 2×10-7.

  2. Harnessing speckle for a sub-femtometre resolved broadband wavemeter and laser stabilization (United States)

    Metzger, Nikolaus Klaus; Spesyvtsev, Roman; Bruce, Graham D.; Miller, Bill; Maker, Gareth T.; Malcolm, Graeme; Mazilu, Michael; Dholakia, Kishan


    The accurate determination and control of the wavelength of light is fundamental to many fields of science. Speckle patterns resulting from the interference of multiple reflections in disordered media are well-known to scramble the information content of light by complex but linear processes. However, these patterns are, in fact, exceptionally rich in information about the illuminating source. We use a fibre-coupled integrating sphere to generate wavelength-dependent speckle patterns, in combination with algorithms based on the transmission matrix method and principal component analysis, to realize a broadband and sensitive wavemeter. We demonstrate sub-femtometre wavelength resolution at a centre wavelength of 780 nm, and a broad calibrated measurement range from 488 to 1,064 nm. This compares favourably to the performance of conventional wavemeters. Using this speckle wavemeter as part of a feedback loop, we stabilize a 780 nm diode laser to achieve a linewidth better than 1 MHz.

  3. A laser spectrometer and wavemeter for pulsed lasers (United States)

    Mckay, J. A.; Laufer, P. M.; Cotnoir, L. J.


    The design, construction, calibration, and evaluation of a pulsed laser wavemeter and spectral analyzer are described. This instrument, called the Laserscope for its oscilloscope-like display of laser spectral structure, was delivered to NASA Langley Research Center as a prototype of a laboratory instrument. The key component is a multibeam Fizeau wedge interferometer, providing high (0.2 pm) spectral resolution and a linear dispersion of spectral information, ideally suited to linear array photodiode detectors. Even operating alone, with the classic order-number ambiguity of interferometers unresolved, this optical element will provide a fast, real-time display of the spectral structure of a laser output. If precise wavelength information is also desired then additional stages must be provided to obtain a wavelength measurement within the order-number uncertainty, i.e., within the free spectral range of the Fizeau wedge interferometer. A Snyder (single-beam Fizeau) wedge is included to provide this initial wavelength measurement. Difficulties in achieving the required wide-spectrum calibration limit the usefulness of this function.

  4. Fibre optics wavemeters calibration using a self-referenced optical frequency comb (United States)

    Galindo-Santos, J.; Velasco, A. V.; Corredera, P.


    Self-referenced optical frequency combs enable the measurement of optical frequencies with a very high accuracy, achieving uncertainties close to the atomic clock used as reference (CSIC and its application to the calibration of two wavemeters in the 1.5 μm optical communication window. Calibration uncertainties down to 12 MHz and 59 MHz were obtained, respectively, for each of the devices. Furthermore, the long-term behaviour of the higher resolution wavemeter was studied during a 750 h period of sustained operation, exhibiting a dispersion in the measurements of 7.72 MHz. Temperature dependence of the device was analysed, enabling to further reduce dispersion down to a 2.15 MHz range, with no significant temporal deviations.

  5. Speckle-based wavemeter

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner; Jakobsen, Michael Linde; Chakrabarti, Maumita


    A spectrometer based on the application of dynamic speckles will be disclosed. The method relies on scattering of primarily coherent radiation from a slanted rough surface. The scattered radiation is collected on a detector array and the speckle displacement is monitored during a change in the in...

  6. 单片机控制的高精度Michelson干涉型波长计%Michelson Interferometer Wave-Meter with High Precision Under the Control of Single-Chip Computer

    Institute of Scientific and Technical Information of China (English)

    彭月祥; 王利强; 宁可庆


    设计了Michelson干涉型激光波长计干涉条纹的单片微机计数硬件电路,编写了8254计数和Keil C51波长运算程序.为提高仪器的测量精度,在硬件和软件上提出了新的设计方案.两个8254计数器可以在单片微机的控制下自动从参考光脉冲信号的下降沿开始对参考信号和被测信号同时计数;参考激光干涉条纹计数满1 500 000后,参考信号和被测信号的计数器可以同时被自动锁定;单片微机得到锁定信号后,完成两个计数值的读取、波长运算、10次移位平均和7位波长显示.对633 nm和532 nm两种稳频激光波长进行了实际测量,测量数据表明该计数系统使波长的测量精度达到2×10-7.

  7. Hard Collisions in Rubidium using Sub-Doppler Spectroscopy (United States)


    Experiment Verdi V-18 ! = 532nm Ti:Sapphire Matisse Ring Laser ! = 780 nm Wavemeter Fabry-Perot Interferrometer Chopper N.D. Filter P.D. N.D. Filter N.D...beam samplers, P.D. are photodiodes, and N.D. Filter are neutral density filters. A diagram of the experiment apparatus can be seen in Fig.9. The Verdi

  8. Heavy Rydberg Photo-dissociation Cross-section Calculations and Experimental Progress Towards Cold Collisions in Lithium

    CERN Document Server

    Ugray, Lisa Madeleine


    This thesis is divided into two parts, each of which supports constructing and using a lithium magneto-optical trap for cold collision studies: Part I: One outgoing channel of interest from cold collisions is the production of ion pairs. We describe an effective method for calculating bound-to-continuum cross-sections for charged binary systems by examining transitions to states above the binding energy that become bound when the system is placed within an infinite spherical well. This approach is verified for ionization of a hydrogen atom, and is then applied to the heavy Rydberg system Li+...I-. Part II: A wavemeter previously built in the lab is redesigned for increased reliability and ease of use by replacing the optical hardware with a rocker system, which can be aligned in mere minutes rather than half a day as was previously the case. The new wavemeter has been tested through saturated absorption spectroscopy of lithium.

  9. Advanced optical design and control of multi-colored SSL system for stage lighting application

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita

    mixing system and provides a solution which is capable of replacing both the Fresnel lens spotlight Halogen lamp (2kW) and the commercially available LED luminaire (~160W), which have applications in stage lighting, theater lighting, TV studio lighting, etc. Since the optical design comprises LEDs...... in wavelength for a laser color mixing system can be detected by a new speckle based wavemeter, which is easy for use and cost‐effective compared to the commercially available expensive spectrometers. The thesis also reports on the fabrication of a tool for replicating the microlens structure used for beam...

  10. Atmospheric transmission for cesium DPAL using TDLAS (United States)

    Rice, Christopher A.; Perram, Glen P.


    The cesium (Cs) Diode Pumped Alkali Laser (DPAL) operates near 894 nm, in the vicinity of atmospheric water vapor absorption lines. An open-path Tunable Diode Laser Absorption (TDLAS) system composed of narrow band (~300 kHz) diode laser fiber coupled to a 12" Ritchey-Chrétien transmit telescope has been used to study the atmospheric transmission characteristics of Cs DPALs over extended paths. The ruggedized system has been field deployed and tested for propagation distances of greater than 1 km. By scanning the diode laser across many free spectral ranges, many rotational absorption features are observed. Absolute laser frequency is monitored with a High Finesse wavemeter to an accuracy of less than 10 MHz. Phase sensitive detection is employed with an absorbance of less than 1% observable under field conditions.

  11. Evaluation of the frequency stability of a VCSEL locked to a micro-fabricated Rubidium vapour cell (United States)

    Di Francesco, J.; Gruet, F.; Schori, C.; Affolderbach, C.; Matthey, R.; Mileti, G.; Salvadé, Y.; Petremand, Y.; De Rooij, N.


    We present our evaluation of a compact laser system made of a 795 nm VCSEL locked to the Rubidium absorption line of a micro-fabricated absorption cell. The spectrum of the VCSEL was characterised, including its RIN, FM noise and line-width. We optimised the signal-to-noise ratio and determined the frequency shifts versus the cell temperature and the incident optical power. The frequency stability of the laser (Allan deviation) was measured using a high-resolution wavemeter and an ECDL-based reference. Our results show that a fractional instability of anodic bonding. The overall thickness of the reference cell is 1.5 mm. No buffer gas was added. The potential applications of this compact and low-consumption system range from optical interferometers to basic laser spectroscopy. It is particularly attractive for mobile and space instruments where stable and accurate wavelength references are needed.

  12. Precise measurements of hyperfine components in the spectrum of molecular iodine

    Energy Technology Data Exchange (ETDEWEB)

    Sansonetti, C.J. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)


    Absolute wave numbers with a typical uncertainty of 1 MHz (95% confidence) were measured for 102 hyperfine-structure components of {sup 127}I{sub 2}. The data cover the range 560-656 nm, with no gaps over 50 cm{sup -1}. The spectra were observed using Doppler-free frequency modulation spectroscopy with tunable cw laser. The laser was locked to selected iodine components and its wave number measured with a high precision Fabry-Perot wavemeter. Accuracy is confirmed by good agreement of 9 of the lines with previous results from other laboratories. These measurements provide a well-distributed set of precise reference lines for this spectral region.

  13. High-power, continuous-wave, mid-infrared optical parametric oscillator based on MgO:sPPLT. (United States)

    Chaitanya Kumar, S; Ebrahim-Zadeh, M


    We report a stable, high-power, cw, mid-IR optical parametric oscillator using MgO-doped stoichiometric periodically poled LiTaO₃ (MgO:sPPLT) pumped by a Yb fiber laser at 1064 nm. The singly resonant oscillator (SRO), based on a 30 mm long crystal, is tunable over 430 nm from 3032 to 3462 nm and can generate as much as 5.5 W of mid-IR output power, with >4 W of over 60% of the tuning range and under reduced thermal effects, enabling room temperature operation. Idler power scaling measurements at ~3.3 μm are compared with an MgO-doped periodically poled LiNbO₃ cw SRO, confirming that MgO:sPPLT is an attractive material for multiwatt mid-IR generation. The idler output at 3299 nm exhibits a peak-to-peak power stability better than 12.8% over 5 h and frequency stability of ~1 GHz, while operating close to room temperature, and has a linewidth of ~0.2 nm, limited by the resolution of the wavemeter. The corresponding signal linewidth at 1570 nm is ~21 MHz.

  14. Absolute frequency measurement of unstable lasers with optical frequency combs (United States)

    Beverini, N.; Poli, N.; Sutyrin, D.; Wang, F.-Y.; Schioppo, M.; Tarallo, M. G.; Tino, G. M.


    Here we report on absolute frequency measurements of a commercial high power CW diode-pumped solid-state laser (Coherent Verdi-V5). This kind of lasers usually presents large frequency jitter (up to 50 MHz) both in the short term (1 ms time scale) and in the long term (>10 s time scale). A precise measurement of absolute frequency deviations in both temporal scales should require a set of different devices (optical cavities, optical wave-meters), each suited for measurements only at a specific integration time. Here we demonstrate how a frequency comb can be used to overcome this difficulty, allowing in a single step a full characterization of both short ( 103 s) absolute frequency jitter with a resolution better than 1 MHz. We demonstrate in this way the flexibility of optical frequency combs for absolute frequency measurements not only of ultra-stable lasers but also of relatively unstable lasers. The absolute frequency calibration of the Verdi laser that we have obtained have been used in order to improve the accuracy of the measurements of the local gravitational acceleration value with 88Sr atoms trapped in 1D vertical lattices.

  15. A robust optical parametric oscillator and receiver telescope for differential absorption lidar of greenhouse gases (United States)

    Robinson, Iain; Jack, James W.; Rae, Cameron F.; Moncrieff, John B.


    We report the development of a differential absorption lidar instrument (DIAL) designed and built specifically for the measurement of anthropogenic greenhouse gases in the atmosphere. The DIAL is integrated into a commercial astronomical telescope to provide high-quality receiver optics and enable automated scanning for three-dimensional lidar acquisition. The instrument is portable and can be set up within a few hours in the field. The laser source is a pulsed optical parametric oscillator (OPO) which outputs light at a wavelength tunable near 1.6 μm. This wavelength region, which is also used in telecommunications devices, provides access to absorption lines in both carbon dioxide at 1573 nm and methane at 1646 nm. To achieve the critical temperature stability required for a laserbased field instrument the four-mirror OPO cavity is machined from a single aluminium block. A piezoactuator adjusts the cavity length to achieve resonance and this is maintained over temperature changes through the use of a feedback loop. The laser output is continuously monitored with pyroelectric detectors and a custom-built wavemeter. The OPO is injection seeded by a temperature-stabilized distributed feedback laser diode (DFB-LD) with a wavelength locked to the absorption line centre (on-line) using a gas cell containing pure carbon dioxide. A second DFB-LD is tuned to a nearby wavelength (off-line) to provide the reference required for differential absorption measurements. A similar system has been designed and built to provide the injection seeding wavelengths for methane. The system integrates the DFB-LDs, drivers, locking electronics, gas cell and balanced photodetectors. The results of test measurements of carbon dioxide are presented and the development of the system is discussed, including the adaptation required for the measurement of methane.