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Sample records for acousto-optic modulators aom

  1. Compact acousto-optic modulator operatingin the purely Raman - Nath diffraction regime as a phase modulator in FM spectroscopy

    SciTech Connect

    Baryshev, Vyacheslav N; Epikhin, V M

    2010-08-03

    We report fabrication of a new acousto-optic modulator (AOM-RN) operating purely in the Raman - Nath diffraction regime. This device can be used as an external phase modulator in frequency-modulation (FM) optical heterodyne spectroscopy for fast and broadband frequency control of diode lasers. The AOM-RN design is significantly simplified, and its dimensions are minimised due to a decrease (by almost an order of magnitude in comparison with the existing AOMs) in the acousto-optic interaction length and the absence of impedance matching circuit. The FM spectroscopy based on AOM-RN makes it possible to analyse both absorption and dispersion properties of optical resonances under study; this possibility is shown by the example of saturated-absorption resonances in cesium vapour. The possibility of detecting coherent population trapping resonances using FM spectroscopy with AOM-RN as an external phase modulator is experimentally demonstrated.

  2. Note: laser frequency shifting by using two novel triple-pass acousto-optic modulator configurations.

    PubMed

    de Carlos-López, E; López, J M; López, S; Espinosa, M G; Lizama, L A

    2012-11-01

    We report the design of two novel triple-pass acousto-optic modulator systems. These designs are extensions of the well known acousto-optic modulator (AOM) double-pass configuration, which eliminates the angle dependence of the diffracted beam with respect to the modulation frequency. In a triple-pass system, however, the frequency dependence of the angle does not disappear but the frequency shift is larger, spanning 3 times the AOM central frequency. In some applications, such as optically pumped Cesium-beam frequency standards, the frequencies of the two laser beams remain fixed and a triple-pass optical system can be used to reduce to one the number of lasers used in such atomic clocks. The two triple-pass configurations use either a retro-reflecting mirror, or a right angle prism to pass for third time the laser beam through the AOM, obtaining diffraction efficiencies of about 27% and 44%, respectively. PMID:23206109

  3. Note: Laser frequency shifting by using two novel triple-pass acousto-optic modulator configurations

    SciTech Connect

    Carlos-Lopez, E. de; Lopez, J. M.; Lopez, S.; Espinosa, M. G.; Lizama, L. A.

    2012-11-15

    We report the design of two novel triple-pass acousto-optic modulator systems. These designs are extensions of the well known acousto-optic modulator (AOM) double-pass configuration, which eliminates the angle dependence of the diffracted beam with respect to the modulation frequency. In a triple-pass system, however, the frequency dependence of the angle does not disappear but the frequency shift is larger, spanning 3 times the AOM central frequency. In some applications, such as optically pumped Cesium-beam frequency standards, the frequencies of the two laser beams remain fixed and a triple-pass optical system can be used to reduce to one the number of lasers used in such atomic clocks. The two triple-pass configurations use either a retro-reflecting mirror, or a right angle prism to pass for third time the laser beam through the AOM, obtaining diffraction efficiencies of about 27% and 44%, respectively.

  4. Emission spectroscopy of laser ablation plasma with time gating by acousto-optic modulator

    SciTech Connect

    Sakka, Tetsuo; Irie, Kyohei; Fukami, Kazuhiro; Ogata, Yukio H.

    2011-02-15

    The capability of acousto-optic modulator (AOM) to perform time-gated measurements for laser ablation plasma spectroscopy has been examined. Especially, we focused on the capability of the ''AOM gating'' to exclude the continuum and extremely broadened spectra usually observed immediately after the laser ablation. Final goal of the use of the AOM is to achieve considerable downsizing of the system for in situ and on-site analyses. In the present paper, it is shown that narrow and clear spectral lines can be obtained with the AOM gating even if the target is submerged in water. Also, application of this technique to the targets in air is demonstrated. It has been revealed that the AOM gating is fast enough to exclude the continuum and broadened lines, while effectively acquiring sufficiently narrow atomic lines lasting slightly longer than the continuum.

  5. Q-switched fiber laser based on an acousto-optic modulator with injection seeding technique.

    PubMed

    Li, Wencai; Liu, Haowei; Zhang, Ji; Long, Hu; Feng, Sujuan; Mao, Qinghe

    2016-06-10

    The operation mechanism and the pulse property of an actively Q-switched erbium-doped fiber laser based on an acousto-optic modulator (AOM) switch with the injection seeding technique are investigated. Our results show that the Q-switched pulses can be locked to oscillate near a fixed frequency higher than that of the seed laser, though the frequency-shift effect of the AOM impedes stable cavity mode oscillations. The operation mechanism of such Q-switch fiber lasers can be explained by the mutual locking-in among the shifted frequency components originated from the injected coherence seed with the help of the gain dynamics of the Q-switch cavity. Moreover, narrow-linewidth Q-switched pulses with different repetition rates can be obtained with different cavity lengths for incredibly stable output pulses without any use of cavity-stabilized techniques. PMID:27409015

  6. Simulation research of acousto optic modulator drive based on Multisim

    NASA Astrophysics Data System (ADS)

    Wang, Shiqian; Guo, Yangkuan; Zhu, Lianqing; Na, Yunxiao; Zhang, Yinmin; Liu, Qianzhe

    2013-10-01

    The acousto optic modulator drive is mainly made with 2 amplitude shift keying (2ASK)circuit, pre-amplifier circuit and power operational amplifier circuit, and the simulation of the acousto optic modulator drive is realized. Firstly, the acousto optic modulator drive works as follows.The modulation function is realized by the analoged switch circuit, and the on-off of the analoged switch chip (CD4066) are controlled by the pulse signal generated by the electronic conversion circuit. The voltage amplification of the modulated signal is achieved by two reverse proportional operation implements voltage amplifier circuit, and the circuit is mainly made with the AD8001 chip. Then the amplified signal is transfered into a two-stage power operational amplifier circuit of class C which is mainly made with the chip of MRF158. Secondly, both of the simulating structures and the union debugging based on the designed system are realized by Multisim. Finally, obtaining the modulation signal of 150(MHz) frequency and 5(μs) pulse width illustrates that a 2ASk modulation of the 150 (MHz)carrier signal and the 20(kHz) modulation signal is achieved. Besides, as the frequency of input signal and amplitude of voltage change, the output power of the power operational amplifier circuit also changes, and the conclusion is drawn that the output power increases when the frequency of input signal decreases and the amplitude of voltage increases. The component selection of the drive's PCB design, the performance parameter and of the actual circuit and the debugging of the actual circuit are based on the simulation results.

  7. Nonlinear dynamics of Ytterbium-doped fiber laser Q-switched using acousto-optical modulator

    NASA Astrophysics Data System (ADS)

    Barmenkov, Y. O.; Kir'yanov, A. V.; Andres, M. V.

    2014-12-01

    A comprehensive experimental analysis of the dynamics of an ytterbium-doped fiber laser actively Q-switched (QS) using an intracavity acousto-optical modulator (AOM) is presented. It is shown that type of QS pulsing strongly depends on AOM repetition rate and pump power. In particular, at low repetition rates, including zero-rate, and at relatively high pump powers peculiar QS pulsing, switched by stimulated Brillouin scattering (SBS), is established in the laser. The cause of such kind of pulsing is the SBS-process boosted by spurious narrow-line CW lasing that arises in auxiliary low-Q cavity formed by an output coupler (in our experiments - fiber Bragg gratings) and weak reflections from blocked AOM. The parameters' area where this regime occurs is limited by certain values of pump power and AOM repetition rate. At increasing AOM repetition rate or decreasing pump power spurious CW lasing is not attained in the system; consequently, the SBS type of QS fades, while "conventional" QS (CQS) lasing is established in the system and remains. However CQS pulsing strongly suffers the nonlinear-dynamics effects: depending on AOM repetition rate and pump power the laser switches to common P1, P2, or P3 attractors, when QS pulses arise at sub-harmonics of AOM repetition rate, or to the specific transient regimes between them, or to chaotic operation. These and other sides (e.g. pulse jittering) of operation of the QS ytterbium-doped fiber laser with AOM are under scope of the present review as they have big interest for practical applications.

  8. Two-frequency acousto-optic modulator driver to improve the beam pointing stability during intensity ramps

    SciTech Connect

    Froehlich, B.; Lahaye, T.; Kaltenhaeuser, B.; Kuebler, H.; Mueller, S.; Koch, T.; Fattori, M.; Pfau, T.

    2007-04-15

    We report on a scheme to improve the pointing stability of the first order beam diffracted by an acousto-optic modulator (AOM). Due to thermal effects inside the crystal, the angular position of the beam can change by as much as 1 mrad when the radio-frequency power in the AOM is reduced to decrease the first order beam intensity. This is done, for example, to perform forced evaporative cooling in ultracold atom experiments using far-off-resonant optical traps. We solve this problem by driving the AOM with two radio frequencies f{sub 1} and f{sub 2}. The power of f{sub 2} is adjusted relative to the power of f{sub 1} to keep the total power constant. Using this, the beam displacement is decreased by a factor of 20. The method is simple to implement in existing experimental setups, without any modification of the optics.

  9. Acousto-optic modulation of a photonic crystal nanocavity with Lamb waves in microwave K band

    SciTech Connect

    Tadesse, Semere A.; Li, Huan; Liu, Qiyu; Li, Mo

    2015-11-16

    Integrating nanoscale electromechanical transducers and nanophotonic devices potentially can enable acousto-optic devices to reach unprecedented high frequencies and modulation efficiency. Here, we demonstrate acousto-optic modulation of a photonic crystal nanocavity using Lamb waves with frequency up to 19 GHz, reaching the microwave K band. The devices are fabricated in suspended aluminum nitride membrane. Excitation of acoustic waves is achieved with interdigital transducers with period as small as 300 nm. Confining both acoustic wave and optical wave within the thickness of the membrane leads to improved acousto-optic modulation efficiency in these devices than that obtained in previous surface acoustic wave devices. Our system demonstrates a scalable optomechanical platform where strong acousto-optic coupling between cavity-confined photons and high frequency traveling phonons can be explored.

  10. Post-Flight Test Results of Acousto-Optic Modulator Devices Subjected to Space Exposure

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Trivedi, Sudhir; Rosemeier, Jolanta; Diestler, Mark

    2014-01-01

    The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment for several months. MISSE missions provide an opportunity for developing space qualifiable materials. Several laser and lidar components were sent by NASA Langley Research Center (LaRC) as a part of the MISSE 7 mission. The MISSE 7 module was transported to the international space station (ISS) via STS 129 mission that was launched on Nov 16, 2009. Later, the MISSE 7 module was brought back to the earth via the STS 134 that landed on June 1, 2011. The MISSE 7 module that was subjected to exposure in a space environment for more than one and a half years included fiber laser, solid-state laser gain materials, detectors, and semiconductor laser diode. Performance testing of these components is now progressing. In this paper, the results of performance testing of a laser diode module sent by NASA Langley Research Center on MISSE 7 mission will be discussed. This paper will present the comparison of pre-flight and post-flight performance of two different COTS acousto-optic modulator (AOM) devices. Post-flight measurements indicate that these two devices did not undergo any significant performance degradation.

  11. Tandem-pulsed acousto-optics: an analytical framework of modulated high-contrast speckle patterns.

    PubMed

    Resink, S G; Steenbergen, W

    2015-06-01

    Recently we presented acousto-optic (AO) probing of scattering media using addition or subtraction of speckle patterns due to tandem nanosecond pulses. Here we present a theoretical framework for ideal (polarized, noise-free) speckle patterns with unity contrast that links ultrasound-induced optical phase modulation, the fraction of light that is tagged by ultrasound, speckle contrast, mean square difference of speckle patterns and the contrast of the summation of speckle patterns acquired at different ultrasound phases. We derive the important relations from basic assumptions and definitions, and then validate them with simulations. For ultrasound-generated phase modulation angles below 0.7 rad (assuming uniform modulation), we are now able to relate speckle pattern statistics to the acousto-optic phase modulation. Hence our theory allows quantifying speckle observations in terms of ultrasonically tagged fractions of light for near-unity-contrast speckle patterns. PMID:25985079

  12. Optoelectronic oscillator using an acousto-optic delay line

    NASA Astrophysics Data System (ADS)

    Yim, Sin Hyuk; Kim, Tae Hyun; Lee, Sangkyung; Roh, Hee Sook; Shim, Kyu Min

    2015-05-01

    We demonstrate an optoelectronic oscillator (OEO) based on an acousto-optic modulator (AOM). The free spectral range between the modes is a function of the total loop length of the OEO, which is dependent on the propagation time of the acoustic wave through the AOM. By using the huge difference in the magnitude between the speed of light and the acoustic velocity in the AOM, we can extend the effective loop length of the OEO up to 3.8 km. We have measured phase noise of the OEO. Further developments will be made by using a dual-loop configuration. Agency for Defense Development.

  13. Laser communication system with acousto-optic tracking and modulation: experimental study

    NASA Astrophysics Data System (ADS)

    Nikulin, Vladimir V.; Sofka, Jozef

    2009-12-01

    Laser communication systems are highly preferred for broadband applications. This technology uses higher regions of the spectrum, and offers unsurpassed throughput, information security, reduced weight and size of the components, and power savings. Unfortunately, small beam divergence requires precise positioning, which becomes very critical at high data rates. Complex motion patterns of the communicating platforms, vibrations, and atmospheric effects cause significant signal losses due to the pointing errors, beam wander, and other higher order effects. Mitigation of those effects is achieved by fast tracking, which can be successfully combined with signal modulation. In this work, we focus on the application of acousto-optic technology and its effect on communication performance. We present experimental results for a laser communication link affected by pointing distortions. These distortions are generated to emulate specific operation environments with particular spectral characteristics. The acousto-optic technology is used to build an agile tracking system combined with signal modulation in the same device to assure maximum signal reception, in spite of the harsh operational conditions. The received communication signal is recorded and statistically analyzed to calculate the bit error rates. This work presents synthesis of a tracking system and experimental results characterizing the communication performance under uncompensated pointing disturbance and with tracking.

  14. Construction and characterization of ultraviolet acousto-optic based femtosecond pulse shapers

    SciTech Connect

    Mcgrane, Shawn D; Moore, David S; Greenfield, Margo T

    2008-01-01

    We present all the information necessary for construction and characterization of acousto optic pulse shapers, with a focus on ultraviolet wavelengths, Various radio-frequency drive configurations are presented to allow optimization via knowledgeable trade-off of design features. Detailed performance characteristics of a 267 nm acousto-optic modulator (AOM) based pulse shaper are presented, Practical considerations for AOM based pulse shaping of ultra-broad bandwidth (sub-10 fs) amplified femtosecond pulse shaping are described, with particular attention paid to the effects of the RF frequency bandwidth and optical frequency bandwidth on the spatial dispersion of the output laser pulses.

  15. Modern optical signal processing experiments demonstrating intensity and pulse-width modulation using an acousto-optic modulator

    NASA Astrophysics Data System (ADS)

    Poon, Ting-Chung; McNeill, Mark D.; Moore, Daniel J.

    1997-09-01

    Two experiments are presented to introduce undergraduate students in electrical engineering or physics to modern optical signal processing. Both experiments use an acousto-optic (AO) Bragg cell together with additional electronics to modify the intensity of a laser beam. Specifically, we show how an AO feedback system operating in the Bragg regime can be configured to produce amplitude modulated (AM) and pulse-width modulated optical signals. The basic components of the AO feedback system include a laser, an AO Bragg cell, an electronic AM modulator, a photodetector, an amplifier, and an electronic adder. Except for the laser, the AM modulator, and the Bragg cell, each of these components can be constructed with low cost electronics. A tutorial outlining the principles of acousto-optics is included to provide sufficient understanding of the Bragg cell. The project described in the paper has been used as a demonstration for junior- and senior-level undergraduate students in electrical engineering communications and optics classes.

  16. Mode locking of an all-fiber laser by acousto-optic superlattice modulation.

    PubMed

    Cuadrado-Laborde, C; Diez, A; Delgado-Pinar, M; Cruz, J L; Andrés, M V

    2009-04-01

    Active mode locking of an erbium-doped all-fiber laser with a Bragg-grating-based acousto-optic modulator is demonstrated. The fiber Bragg grating was acoustically modulated by a standing longitudinal elastic wave, which periodically modulates the sidebands at twice the acoustic frequency. The laser has a Fabry-Perot configuration in which cavity loss modulation is achieved by tuning the output fiber Bragg grating to one of the acoustically induced sidebands. Optical pulses at 9 MHz repetition rate, 120 mW peak power, and 780 ps temporal width were obtained. The output results to be stable and has a timing jitter below 40 ps. The measured linewidth, 2.8 pm, demonstrates that these pulses are transform limited. PMID:19340236

  17. Addressable, large-field second harmonic generation microscopy based on 2D acousto-optical deflector and spatial light modulator

    PubMed Central

    Shao, Yonghong; Liu, Honghai; Qin, Wan; Qu, Junle; Peng, Xiang; Niu, Hanben

    2013-01-01

    We present an addressable, large-field second harmonic generation microscope by combining a 2D acousto-optical deflector with a spatial light modulator. The SLM shapes an incoming mode-locked, near-infrared Ti:Sapphire laser beam into a multifocus array, which can be rapidly scanned by changing the incident angle of the laser beam using a 2D acousto-optical deflector. Compared to the single-beam-scan technique, the multifocus array scan can increase the scanning rate and the field-of-view size with the multi-region imaging ability. PMID:24307756

  18. Modulation frequency characteristics of the Q-switched envelope in a doubly Q-switched and mode-locked laser with acousto-optic modulator and Cr4+:YAG saturable absorber

    NASA Astrophysics Data System (ADS)

    Qiao, Junpeng; Zhao, Jia; Li, Yufei; Zhao, Shengzhi; Li, Guiqiu; Li, Dechun; Qiao, Wenchao; Chu, Hongwei

    2015-11-01

    The modulation frequency characteristics of the Q-switched envelope in a doubly Q-switched and mode-locked Nd:GGG laser with an acousto-optic modulator (AOM) and Cr4+:YAG saturable absorber are given. At a fixed incident pump power, the repetition rates of the Q-switched envelope and the related laser characteristics versus the modulation frequency of AOM for different small signal transmissions of Cr4+:YAG saturable absorbers have been measured. The experimental results show that the repetition rates of the Q-switched envelope, the average output power, the average peak power, and the pulse widths of the Q-switched envelopes are subharmonics of the modulation frequency at a fixed incident pump power. Furthermore, the mechanism for these behaviors is discussed.

  19. Actively mode-locked fiber ring laser by intermodal acousto-optic modulation.

    PubMed

    Bello-Jiménez, M; Cuadrado-Laborde, C; Sáez-Rodríguez, D; Diez, A; Cruz, J L; Andrés, M V

    2010-11-15

    We report an actively mode-locked fiber ring laser. A simple and low-insertion-loss acousto-optic modulator driven by standing flexural waves, which couples core-to-cladding modes in a standard single-mode optical fiber, is used as an active mechanism for mode locking. Among the remarkable features of the modulator, we mention its high modulation depth (72%), broad bandwidth (187 GHz), easy tunability in the optical wavelength, and low insertion losses (0.7 dB). The narrowest optical pulses obtained were of 95 ps time width, 21 mW peak power, repetition rate of 4.758 MHz, and 110 mW of pump power. PMID:21081995

  20. Gain-switched Ho:YAG ceramic laser with an acousto-optic modulator

    NASA Astrophysics Data System (ADS)

    Zhang, Jianing; Shen, Deyuan; Zhang, Jian; Tang, Dingyuan; Chen, Hao

    2016-04-01

    We demonstrate a gain-switched Ho:YAG ceramic laser in-band pumped by an acousto-optically modulated thulium fiber laser at ˜1908 nm. The laser pulse repetition rate could be tuned continuously from 60 to 100 kHz with the pulse energy kept constant for a certain pump power level. The shortest pulse width of 204 ns and a maximum peak power of 75 W have been obtained at 60 kHz under the maximum pump power level of 11 W. A maximum average output power of 1.4 W has been achieved with a pulse repetition rate of 100 kHz, corresponding to a slope efficiency of 57% with respect to the incident pump power. The prospects for further improvement in laser performance are discussed.

  1. Secure chaotic transmission of electrocardiography signals with acousto-optic modulation under profiled beam propagation.

    PubMed

    Almehmadi, Fares S; Chatterjee, Monish R

    2015-01-10

    Electrocardiography (ECG) signals are used for both medical purposes and identifying individuals. It is often necessary to encrypt this highly sensitive information before it is transmitted over any channel. A closed-loop acousto-optic hybrid device acting as a chaotic modulator is applied to ECG signals to achieve this encryption. Recently improved modeling of this approach using profiled optical beams has shown it to be very sensitive to key parameters that characterize the encryption and decryption process, exhibiting its potential for secure transmission of analog and digital signals. Here the encryption and decryption is demonstrated for ECG signals, both analog and digital versions, illustrating strong encryption without significant distortion. Performance analysis pertinent to both analog and digital transmission of the ECG waveform is also carried out using output signal-to-noise, signal-to-distortion, and bit-error-rate measures relative to the key parameters and presence of channel noise in the system. PMID:25967617

  2. High-peak-power sub-nanosecond intracavity KTiOPO4 optical parametric oscillator pumped by a dual-loss modulated laser with acousto-optic modulator and single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Qiao, Junpeng; Zhao, Shengzhi; Yang, Kejian; Zhao, Jia; Li, Guiqiu; Li, Dechun; Li, Tao; Qiao, Wenchao; Lu, Jianren; Wang, Yonggang; Chu, Hongwei; Luan, Chao

    2016-08-01

    A high-peak-power low-repetition-rate sub-nanosecond intracavity KTiOPO4 (KTP) optical parametric oscillator (OPO) pumped by a doubly Q-switched and mode-locked (QML) YVO4/Nd:YVO4 laser with an acousto-optic modulator (AOM) and a single-walled carbon nanotube saturable absorber (SWCNT-SA) has been demonstrated. A maximum output power of 373 mW at a signal wavelength of 1570 nm was obtained. The smallest pulse width, highest pulse energy, and greatest peak power of mode-locking pulses were estimated to be 119 ps, 124 µJ, and 1.04 MW, respectively, under a maximum incident pump power of 8.3 W and an AOM repetition rate of 2 kHz. This OPO operation paves a simple way to produce eye-safe laser sources at 1570 nm with low repetition rates, small pulse widths, and high peak powers.

  3. Post-flight test results of acousto-optic modulator devices subjected to space exposure

    NASA Astrophysics Data System (ADS)

    Prasad, Narasimha S.; Trivedi, Sudhir; Rosemeier, Jolanta; Diestler, Mark

    2014-09-01

    The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment for several months. MISSE missions provide an opportunity for developing space qualifiable materials. Several laser and lidar components were sent by NASA Langley Research Center (LaRC) as a part of the MISSE 7 mission. The MISSE 7 module was transported to the international space station (ISS) via STS 129 mission that was launched on Nov 16, 2009. Later, the MISSE 7 modulewas brought back to the earth via the STS 134 that landed on June 1, 2011. The MISSE 7 module that was subjected to exposure in space environment for more than one and a half year included fiber laser, solid-state laser gain materials, detectors, and semiconductor laser diode. Performance testing of these components is now progressing. In this paper, the results of performance testing of a laser diode module sent by NASA Langley Research Center on MISSE 7 mission will be discussed. This paper will present the comparison of pre-flight and post-flight performance of two different COTS acousto-optic modulator devices. Post-flight measurements indicate that these two devices did not undergo any significant performance degradation.

  4. Self-acousto-optic modulation and orthogonality violation in the transverse modes of a broad-area Nd-doped yttrium-aluminum-garnet single-shot laser

    SciTech Connect

    Soler Rus, M. Odin; Cabrera-Granado, E.; Guerra Perez, J. M.

    2011-05-15

    Self-acousto-optic Raman-Nath modulation and nonorthogonal transversal modes are found in a broad-area Nd:YAG single-shot laser. The device is free from the thermal-induced effects previously related to orthogonality violation and the acousto-optic modulation comes from a shock wave produced by the discharge of the flash lamps that optically pump the laser. The experimental findings are reproduced by a general model of a class B laser.

  5. Wave packet interferometry and quantum state reconstruction by acousto-optic phase modulation

    SciTech Connect

    Tekavec, Patrick F.; Dyke, Thomas R.; Marcus, Andrew H.

    2006-11-21

    Studies of wave packet dynamics often involve phase-selective measurements of coherent optical signals generated from sequences of ultrashort laser pulses. In wave packet interferometry (WPI), the separation between the temporal envelopes of the pulses must be precisely monitored or maintained. Here we introduce a new (and easy to implement) experimental scheme for phase-selective measurements that combines acousto-optic phase modulation with ultrashort laser excitation to produce an intensity-modulated fluorescence signal. Synchronous detection, with respect to an appropriately constructed reference, allows the signal to be simultaneously measured at two phases differing by 90 deg. Our method effectively decouples the relative temporal phase from the pulse envelopes of a collinear train of optical pulse pairs. We thus achieve a robust and high signal-to-noise scheme for WPI applications, such as quantum state reconstruction and electronic spectroscopy. The validity of the method is demonstrated, and state reconstruction is performed, on a model quantum system - atomic Rb vapor. Moreover, we show that our measurements recover the correct separation between the absorptive and dispersive contributions to the system susceptibility.

  6. Wave packet interferometry and quantum state reconstruction by acousto-optic phase modulation

    NASA Astrophysics Data System (ADS)

    Tekavec, Patrick F.; Dyke, Thomas R.; Marcus, Andrew H.

    2006-11-01

    Studies of wave packet dynamics often involve phase-selective measurements of coherent optical signals generated from sequences of ultrashort laser pulses. In wave packet interferometry (WPI), the separation between the temporal envelopes of the pulses must be precisely monitored or maintained. Here we introduce a new (and easy to implement) experimental scheme for phase-selective measurements that combines acousto-optic phase modulation with ultrashort laser excitation to produce an intensity-modulated fluorescence signal. Synchronous detection, with respect to an appropriately constructed reference, allows the signal to be simultaneously measured at two phases differing by 90°. Our method effectively decouples the relative temporal phase from the pulse envelopes of a collinear train of optical pulse pairs. We thus achieve a robust and high signal-to-noise scheme for WPI applications, such as quantum state reconstruction and electronic spectroscopy. The validity of the method is demonstrated, and state reconstruction is performed, on a model quantum system—atomic Rb vapor. Moreover, we show that our measurements recover the correct separation between the absorptive and dispersive contributions to the system susceptibility.

  7. A novel acousto-optic modulation-deflection mechanism using refractive index grating as graded index beam router

    NASA Astrophysics Data System (ADS)

    Jangjoo, Alireza; Reza Baezzat, Mohammad; Razavizadeh, Ahmad

    2014-03-01

    A novel acousto-optic modulation mechanism will be addressed in this paper. Focused Gaussian beam passing through acousto-optic media experiences different refractive index regions arising from acoustic waves generated by ultrasonic source. In this way according to the snell's law of refraction the beam propagation path will be altered when these periodic traveling waves reach the incoming radiation where a typical p-n junction photodiode located inside the rising or falling lobe of the undiffracted Gaussian beam senses these small lateral deflections. Due to small variations of the refractive index the magnitude of deflection will be up to tens of micron outside the modulator. Hence, sharp intensity gradient is required for detecting such small beam movements by appropriate lens configuration to focus the Gaussian profile on the detector junction area. In the other words intensity profile of zero order beam oscillates proportional to the time dependent amplitude of the acoustic waves versus previous methods that intensity of diffracted beam changes with applied ultrasonic intensity. The extracted signal properties depend on the beam collimation, quality of beam profile and depth of focus inside the modulator. The first experimental approach was proceeded using a collimated 532 nm diode laser source (TEM00), distilled water as interaction media and 10 MHz transducer as ultrasonic generator where a cylindrical glass column with input-output flat windows was used for liquid support. The present method has advantages over common acoustooptical techniques as low cost, simplicity of operation, direct modulation of the signal and minimum alignment requirement.

  8. Optical single sideband modulation radio over fiber system by using a fiber-Bragg-grating-based acousto-optic filter

    NASA Astrophysics Data System (ADS)

    Gao, Song; Pei, Li; Li, Zhuoxuan; Liu, Chao; Wang, Yiqun; Weng, Sijun

    2013-03-01

    An optical single sideband (OSSB) modulation radio over a fiber system, by using an acousto-optic filter (AOF), is proposed and demonstrated. In the AOF, a uniform fiber Bragg grating is etched and modulated by an axially propagating acoustic wave. Due to the acousto-optic superlattice modulation, two secondary reflection peaks, centered on the primary reflection peak, are generated. In the scheme, an optical double-sideband signal passes though the AOF to realize OSSB modulation. Because the reflect depth of the primary peak is much deeper than those of the secondary peaks, the carrier experiences higher attenuation than the upper sideband, which means the carrier-to-sideband ratio (CSR) can be optimized at the same time. We demonstrate this scheme via simulations, and successfully reduce the CSR from 9.73 to 2.9 dB. As a result, the receiving sensitivity improved from -23.43 to -31.18 dBm at BER of 10-9 with 30 km long SMF.

  9. Acousto-Optic Devices For Use In Radio Frequency Target Simulators

    NASA Astrophysics Data System (ADS)

    Kirchner, Ernst K.

    1980-01-01

    Acousto-optic devices have been analyzed and developed for use as modulators, filters and correlators, and in spectrum analyzers. The ability of the acousto-optic unit to amplitude-modulate, frequency-modulate, and deflect laser beams, makes them suitable for these applications. The various signal processing and control functions provided by the acousto-optic devices are optimized by controlling the ratio of divergence angles of the optical beam and the acoustic beam in the acousto-optic interaction region. Another application of acousto-optic devices is to simulate moving targets to test fuzing altimeters and active missile control systems. The frequency modulation, amplitude modulation, and deflection properties of acousto-optic components are all utilized in a single acousto-optic unit to provide the variable range and Doppler simulation. Development of a suitable acousto-optic component for this simulation application is described, as is a description of a simulator employing this acousto-optic device.

  10. Precise modulation of laser radiation by an acousto-optic modulator for stabilisation of the Nd : YAG laser on optical resonances in molecular iodine

    NASA Astrophysics Data System (ADS)

    Denisov, V. I.; Ignatovich, S. M.; Kvashnin, N. L.; Skvortsov, M. N.; Farnosov, S. A.

    2016-05-01

    A system of precise frequency modulation of laser radiation by an acousto-optic modulator, which makes it possible to stabilise the radiation power and simultaneously suppress the residual amplitude modulation to a level of 10-8 of the total laser power at the third harmonic of modulation frequency (~500 Hz), is presented. The use of this system for the Nd : YAG/I2 optical frequency standard and application of digital signal synthesis and processing methods provided a level of frequency standard instability as small as ~10-15 for ~6 × 104 s.

  11. Dual-loss-modulated Q-switched Tm:LuAG laser with AOM and monolayer graphene.

    PubMed

    Luan, Chao; Yang, Ke Jian; Zhao, Jia; Zhao, Sheng Zhi; Qiao, Wen Chao; Li, Tao; Feng, Tian Li; Liu, Cheng; Qiao, Jun Peng; Zheng, Li He; Xu, Jun; Wang, Qing Guo; Su, Liang Bi

    2015-09-20

    A laser-diode-pumped dual-loss-modulated Q-switching Tm:LuAG laser with an acousto-optic modulator (AOM) and monolayer graphene saturable absorber (SA) around 2 μm is presented for the first time to the best of our knowledge. The average output power and the pulse widths for different repetition rates have been measured. In comparison with the singly Q-switching laser with AOM or with monolayer graphene SA, the dual-loss-modulated Q-switching laser could generate shorter pulse width and higher peak power. The maximum pulse width compression ratio was found to be 3.11, and the highest peak power was enhanced 97.4 times. The experimental results show that the dual-loss-modulated technology is an efficient method for compressing the pulse width, improving the peak power, and enhancing the pulse stability for the Q-switched lasers at 2 μm. PMID:26406500

  12. Acousto-optic modulation of a fiber Bragg grating in suspended core fiber for mode-locked all-fiber lasers

    NASA Astrophysics Data System (ADS)

    Silva, Ricardo E.; Tiess, Tobias; Becker, Martin; Eschrich, Tina; Rothhardt, Manfred; Jäger, Matthias; Pohl, Alexandre A. P.; Bartelt, Hartmut

    2015-04-01

    The interaction of a fiber Bragg grating and longitudinal acoustic waves in a three-air-holes suspended core fiber is experimentally investigated and employed to mode-lock an ytterbium-doped fiber laser. An optimized design of an acousto-optic modulator based on two piezoelectric transducers and 1 cm grating length is also proposed. For an electrical signal strength of 10 V applied to the modulator, the results indicate output pulses with a width of less than 550 ps at a repetition rate of 10 MHz. The reduction of the grating length and the power consumed by the transducer, when compared to previous studies, points out to more efficient, compact and fast acousto-optic modulators for mode-locked all-fiber lasers.

  13. LIGHT MODULATION: Quasi-collinear tunable acousto-optic paratellurite crystal filters for wavelength division multiplexing and optical channel selection

    NASA Astrophysics Data System (ADS)

    Molchanov, V. Ya; Voloshinov, V. B.; Makarov, O. Yu

    2009-04-01

    Quasi-collinear acousto-optic interaction is studied in acoustically and optically anisotropic paratellurite crystals. The possible applications of this interaction in acousto-optic tunable filters with a high spectral resolution are discussed. Different modifications of devices are compared and variants of devices intended for processing light beams and selection of light signals in fibreoptic communication systems with wavelength division multiplexing (WDM) at λ simeq 1550 nm are considered.

  14. An experimental distribution of analog and digital information in a hybrid wireless visible light communication system based on acousto-optic modulation and sinusoidal gratings

    NASA Astrophysics Data System (ADS)

    Gómez Colín, R.; García Juárez, A.; Zaldívar Huerta, I. E.; Marquina, A. Vera; García Delgado, L. A.; Leal Cruz, A. L.; Gómez Fuentes, R.

    2016-03-01

    In this paper we propose a photonic architecture as an alternative tool to distribute point to multipoint analog and digital information over a hybrid wireless visible optical communication system. The experimental set-up is composed of a red laser pointer, an acousto-optic modulator, a sinusoidal grating and a photo-detector array. By using a simple and variable interferometric system, diffraction gratings with different spatial frequencies are generated and recorded on a photoemulsion which is composed of vanilla with dichromate gelatin. Analog video and digital information are first transmitted and recovered over a wireless communication system using a microwave carrier at 4.52 GHz which is generated by distributed feedback lasers operating in the low laser threshold current region. Separately, the recovered video information and digital data are combined with a radio frequency signal of 80 MHz, obtaining a subcarrier of information that is imposed on the optical carrier of the pointer laser using an acousto-optic modulator which is operated with an angle of incident light that satisfies the Bragg condition. The modulated optical carrier is sent to a sinusoidal grating, the diffraction pattern is photo-detected using an array of PIN photo-detectors. The use of sinusoidal gratings with acousto-optic modulators allows that number of channels to be increased when both components are placed in cascade.

  15. Laser frequency stabilisation by the Pound - Drever - Hall method using an acousto-optic phase modulator operating in the pure Raman - Nath diffraction regime

    SciTech Connect

    Baryshev, Vyacheslav N

    2012-04-30

    Frequency stabilisation of diode laser radiation has been implemented by the Pound - Drever - Hall method using a new acousto-optic phase modulator, operating in the pure Raman - Nath diffraction regime. It is experimentally shown that, as in the case of saturated-absorption spectroscopy in atomic vapour, the spatial divergence of the frequency-modulated output spectrum of this modulator does not interfere with obtaining error signals by means of heterodyne frequency-modulation spectroscopy with a frequency discriminator based on a high-Q Fabry - Perot cavity with finesse of several tens of thousands.

  16. Fast mode-hop-free acousto-optically tuned laser: theoretical and experimental investigations.

    PubMed

    Bösel, André; Salewski, Klaus-Dieter

    2009-02-10

    We developed a theory that describes fast mode-hop-free tuning of an external cavity diode laser in Littrow configuration with two acousto-optic modulators (AOMs) inside the laser cavity. The theory is based on synchronous shifting of the external cavity modes and the Littrow grating selectivity. It allows calculating the driving signals of both AOMs in order to reach a desired temporal variation of the laser frequency, including particularly fast tuning as well as an arbitrary shape of the tuning function. Furthermore, we present a laser setup for which the needed signals for both AOMs are generated by two direct digital synthesizer circuits. Thereby we were able to verify the theoretical predictions experimentally, achieving, e.g., sinusoidal single-mode tuning of the laser frequency over 40 GHz at a repetition rate of 10 kHz and over 12 GHz at 25 kHz. Finally, the limitations of the theory are discussed. PMID:19209191

  17. Fast mode-hop-free acousto-optically tuned laser with a simple laser diode.

    PubMed

    Bösel, André; Salewski, Klaus-Dieter; Kinder, Thomas

    2007-07-01

    A mode-hop-free tunable external-cavity Littrow diode laser with intracavity acousto-optic modulators (AOMs) has been built. The modes of the red laser diode without a special antireflection coating are shifted by varying the injection current. The external resonator modes and the grating selectivity are independently electrically alterable by two AOMs. Thus, a tuning of the external resonator over up to 1900 GHz is possible. A precise computer control of laser diode and AOMs allowed a single-mode tuning of the whole laser with a tuning range of 225 GHz in 250 s. Additionally, we demonstrated fast tuning over 90 GHz in 190 micros and a repetition rate of 2.5 kHz. PMID:17603626

  18. LIGHT MODULATION: Wide-aperture diffraction of unpolarised radiation in a system of two acousto-optic filters

    NASA Astrophysics Data System (ADS)

    Magdich, L. N.; Yushkov, K. B.; Voloshinov, V. B.

    2009-04-01

    Light diffraction is studied in two tandem acousto-optic cells filtering unpolarised radiation with a wide angular spectrum. It is shown that the side lobes of the ultrasonic radiation pattern of a piezoelectric transducer produce side diffraction intensity maxima at the output of the system consisting of two filters. Diffraction in paratellurite filters is studied experimentally at 1.06 μm.

  19. Acousto-optic spectrometer for radio astronomy

    NASA Technical Reports Server (NTRS)

    Chin, G.; Buhl, D.; Florez, J. M.

    1980-01-01

    Recent developments in acousto-optic techniques and in photodetector arrays have made feasible a new type of RF spectrometer, offering the advantages of wide bandwidth, high resolution, large number of channels in compact, lightweight, energy efficient, and relatively low cost systems. Such a system employs an acousto-optic diffraction cell which serves the key role of converting RF signals to ultrasonic traveling-waves modulating the optical index of the cell. The cell is illuminated across its aperture by a monochromatic laser beam. A fraction of the light is diffracted by the acoustic waves. A focusing lens follows the cell and essentially performs a Fourier transform of the RF signal into a far-field intensity pattern. CSIRO in Australia and the Tokyo Astronomical Observatory in Japan have taken the lead in using acousto-optic techniques in astronomical applications. The first practical device was successfully made at CSIRO for obtaining dynamical spectrographs of solar radio emission.

  20. Acousto-optic tomography using amplitude-modulated focused ultrasound and a near-IR laser

    SciTech Connect

    Yao Yong; Xing Da; He Yonghong; Ueda, Ken-ichi

    2001-11-30

    A novel tomographic method that can be applied in strongly scattering optical media is proposed. 1-MHz focused ultrasound is used to tag the scattering photons in the biological tissue; it carries a 10-KHz sinusoidal wave to act as a detection wave through amplitude-modulation (AM). The scattering photons that come from the focused zone carry the modulated information. Their optoelectronic signal is demodulated by real-time FFT. By detecting and discriminating ultrasound-modulated information carried by scattered photons, the optical tomographic images of the media simulating biological tissue and of a buried object are reconstructed by the AM spectral intensity. This ultrasound-tagged optical tomography can be applied to tissue structures with different optical parameters. For the first time, by using this method, we obtained the tomographic image of a 5 mm-wide soft rubber cube buried in a biological tissue-simulating media with a detecting depth of 30 mm. (laser applications and other topics in quantum electronics)

  1. Detachable 400-MHz acousto-optic phase modulator for a single-mode optical fiber.

    PubMed

    Patterson, D B; Godil, A A; Kino, G S; Khuri-Yakub, B T

    1989-02-15

    A single-mode-fiber phase modulator was constructed by contacting the fiber with a lapped glass capillary tube. The capillary's inner surface provides a long, effectively semicircular contact region to the fiber, allowing throughput of acoustic waves launched from a thin-film ZnO transducer fabricated directly onto the capillary's other lapped face. The device operated at a center frequency of 416 MHz with a FWHM bandwidth of 14 MHz. The maximum phase shift was 0.033 rad/ radicalmw, with a largest measured value of 1.2 rad at 1.3-W input electrical power. PMID:19749885

  2. External cavity quantum cascade lasers with ultra rapid acousto-optic tuning

    SciTech Connect

    Lyakh, A. Barron-Jimenez, R.; Dunayevskiy, I.; Go, R.; Patel, C. Kumar N.

    2015-04-06

    We report operation of tunable external cavity quantum cascade lasers with emission wavelength controlled by an acousto-optic modulator (AOM). A long-wave infrared quantum cascade laser wavelength tuned from ∼8.5 μm to ∼9.8 μm when the AOM frequency was changed from ∼41MHz to ∼49 MHz. The laser delivered over 350 mW of average power at the center of the tuning curve in a linewidth of ∼4.7 cm{sup −1}. Measured wavelength switching time between any two wavelengths within the tuning range of the QCL was less than 1 μs. Spectral measurements of infrared absorption features of Freon demonstrated a capability of obtaining complete spectral data in less than 20 μs.

  3. External cavity quantum cascade lasers with ultra rapid acousto-optic tuning

    NASA Astrophysics Data System (ADS)

    Lyakh, A.; Barron-Jimenez, R.; Dunayevskiy, I.; Go, R.; Patel, C. Kumar N.

    2015-04-01

    We report operation of tunable external cavity quantum cascade lasers with emission wavelength controlled by an acousto-optic modulator (AOM). A long-wave infrared quantum cascade laser wavelength tuned from ˜8.5 μm to ˜9.8 μm when the AOM frequency was changed from ˜41MHz to ˜49 MHz. The laser delivered over 350 mW of average power at the center of the tuning curve in a linewidth of ˜4.7 cm-1. Measured wavelength switching time between any two wavelengths within the tuning range of the QCL was less than 1 μs. Spectral measurements of infrared absorption features of Freon demonstrated a capability of obtaining complete spectral data in less than 20 μs.

  4. High repetition rate laser-induced breakdown spectroscopy using acousto-optically gated detection

    NASA Astrophysics Data System (ADS)

    Pořízka, Pavel; Klessen, Benjamin; Kaiser, Jozef; Gornushkin, Igor; Panne, Ulrich; Riedel, Jens

    2014-07-01

    This contribution introduces a new type of setup for fast sample analysis using laser-induced breakdown spectroscopy (LIBS). The novel design combines a high repetition rate laser (up to 50 kHz) as excitation source and an acousto-optical modulator (AOM) as a fast switch for temporally gating the detection of the emitted light. The plasma radiation is led through the active medium of the AOM where it is diffracted on the transient ultrasonic Bragg grid. The diffracted radiation is detected by a compact Czerny-Turner spectrometer equipped with a CCD line detector. Utilizing the new combination of high repetition rate lasers and AOM gated detection, rapid measurements with total integration times of only 10 ms resulted in a limit of detection (LOD) of 0.13 wt.% for magnesium in aluminum alloys. This short integration time corresponds to 100 analyses/s. Temporal gating of LIP radiation results in improved LODs and consecutively higher sensitivity of the LIBS setup. Therefore, an AOM could be beneficially utilized to temporally detect plasmas induced by high repetition rate lasers. The AOM in combination with miniaturized Czerny-Turner spectrometers equipped with CCD line detectors and small footprint diode pumped solid state lasers results in temporally gateable compact LIBS setups.

  5. High repetition rate laser-induced breakdown spectroscopy using acousto-optically gated detection

    SciTech Connect

    Pořízka, Pavel; Kaiser, Jozef

    2014-07-15

    This contribution introduces a new type of setup for fast sample analysis using laser-induced breakdown spectroscopy (LIBS). The novel design combines a high repetition rate laser (up to 50 kHz) as excitation source and an acousto-optical modulator (AOM) as a fast switch for temporally gating the detection of the emitted light. The plasma radiation is led through the active medium of the AOM where it is diffracted on the transient ultrasonic Bragg grid. The diffracted radiation is detected by a compact Czerny-Turner spectrometer equipped with a CCD line detector. Utilizing the new combination of high repetition rate lasers and AOM gated detection, rapid measurements with total integration times of only 10 ms resulted in a limit of detection (LOD) of 0.13 wt.% for magnesium in aluminum alloys. This short integration time corresponds to 100 analyses/s. Temporal gating of LIP radiation results in improved LODs and consecutively higher sensitivity of the LIBS setup. Therefore, an AOM could be beneficially utilized to temporally detect plasmas induced by high repetition rate lasers. The AOM in combination with miniaturized Czerny-Turner spectrometers equipped with CCD line detectors and small footprint diode pumped solid state lasers results in temporally gateable compact LIBS setups.

  6. Tandem pulsed acousto-optics: obtaining the tagged light fraction from modulated non-ideal speckle patterns

    NASA Astrophysics Data System (ADS)

    Resink, S. G.; Steenbergen, W.

    2016-01-01

    Recently we presented novel methods for acousto-optic (AO) imaging of biological tissues, taking (1) the mean square difference of speckle patterns (subtraction method) or (2) the contrast of the summation of speckle patterns (summation method) acquired from nanosecond pulses of coherent light, fired at different ultrasound phases. In this study we relate the two methods both analytically and experimentally. We experimentally show that these two methods are nearly identical provided that the maximum achievable speckle contrast is determined correctly. We show with simulations that after correction the outcome is independent of experimental detection parameters. This makes the AO methods in this study reliable, allowing quantifying speckle observations in terms of the ultrasonically tagged fractions of light. The use of tandem nanosecond pulses in one burst of ultrasound overcomes the challenge of tissue dynamics.

  7. Study of radiation-induced effects in photonic devices: Acousto-optic modulators and deflectors. Final report, 15 August 1991--15 August 1997

    SciTech Connect

    Taylor, E.W.; Sanchez, A.D.; Winter, J.E.; McKinney, S.J.; Paxton, A.H.

    1998-01-01

    In a preliminary report acousto-optic devices (AODs) were exposed to flash x-ray, linearly accelerated electrons, and gamma ray irradiations to determine their sensitivity to radiation and applicability to space and enhanced radiation environments. This final report is a continuation and finalization of those initial studies and details the findings of a comprehensive investigation of radiation induced effects in lead molybdate (PbMoO{sub 4}), gallium phosphide (GaP) , indium phosphide (InP), tellurium dioxide (TeO{sub 2}), and lithium niobate (LiNbO{sub 3}) acousto-optic Bragg cell deflectors and modulators. Gamma ray, X-ray, electrons, proton and neutron irradiations were conducted to bound, delineate and differentiate radiation induced changes to operational AO Bragg Cells. The majority of the irradiations were performed in situ, wherein the Bragg cells were fully operational during the radiation exposures. Using this approach, instantaneous changes to Bragg cell parameters such as spatial intensities, deflection angles, bandwidth, material absorption, diffraction efficiency and polarization states were determined. A majority of the radiation induced effects observed were determined to evolve from the heating associated with the interaction of radiation with matter, thus resulting in observable thermo-optic effects. The effects of heating in AO Bragg crystals were investigated and confirmed using three independent approaches: traditional broad area source irradiations, ion microbeam irradiations, and irradiation by a CO{sub 2} laser. It was concluded that AO Bragg deflectors and modulators are quite insensitive to the long term low dose radiation environments that would be encountered in the natural space environment. However, under pulsed high dose (or high fluence) irradiations, Bragg cell transient responses could result in disruption of normal operations.

  8. MTF formalism for measurement of spectral resolution of acousto-optical devices with synthesized transmission function.

    PubMed

    Yushkov, Konstantin B; Molchanov, Vladimir Ya

    2013-09-15

    We demonstrate use of the modulation transfer function method in the spectral domain for dynamic measurement of the spectral resolution and modulation contrast of acousto-optic light dispersive delay lines and programmable filters with synthesized transmission. The method is useful for performance characterization of acousto-optic devices for ultrafast pulse shaping and adaptive spectroscopy. PMID:24104818

  9. Holographic topography using acousto-optically generated large synthetic wavelengths

    NASA Astrophysics Data System (ADS)

    Abeywickrema, U.; Beamer, D.; Banerjee, P.; Poon, T.-C.

    2016-03-01

    Digital holography uses phase imaging in a variety of techniques to produce a three-dimensional phase resolved image that includes accurate depth information about the object of interest. Multi-wavelength digital holography is an accurate method for measuring the topography of surfaces. Typically, the object phases are reconstructed for two wavelengths separately and the phase corresponding to the synthetic wavelength (obtained from the two wavelengths) is obtained by calculating the phase difference. Then the surface map can be obtained using proper phase-unwrapping techniques. Usually these synthetic wavelengths are on the order of microns which can be used to resolve depths on the order of microns. In this work, two extremely close wavelengths generated by an acousto-optic modulator (AOM) are used to perform two-wavelength digital holography. Since the difference between the two wavelengths is on the order of picometers, a large synthetic wavelength (on the order of centimeters) can be obtained which can be used to determine the topography of macroscopic surface features. Also since the synthetic wavelength is large, an accurate surface map can be obtained without using a phase-unwrapping technique. A 514 nm Argon-ion laser is used as the optical source, and used with an AOM to generate the zeroth-order and frequency-shifted first-order diffracted orders which are used as the two wavelengths. Both beams are aligned through the same spatial filter assembly. Holograms are captured sequentially using a typical Mach-Zehnder interferometric setup by blocking one beam at a time. Limitations of the large synthetic wavelength are also discussed.

  10. Hybrid wide-band, low-phase-noise scheme for Raman lasers in atom interferometry by integrating an acousto-optic modulator and a feedback loop.

    PubMed

    Wang, Kai; Yao, Zhanwei; Li, Runbing; Lu, Sibin; Chen, Xi; Wang, Jin; Zhan, Mingsheng

    2016-02-10

    We report a hybrid scheme for phase-coherent Raman lasers with low phase noise in a wide frequency range. In this scheme, a pair of Raman lasers with a frequency difference of 3.04 GHz is generated by the ±1-order diffracted lights of an acousto-optic modulator (1.52 GHz), where a feedback loop is simultaneously applied for suppressing the phase noise. The beat width of the Raman lasers is narrower than 3 Hz. In the low-frequency range, the phase noise of the Raman lasers is suppressed by 35 dB with the feedback. The phase noise is less than -109  dBc/Hz in the high-frequency range. The sensitivity of an atom gyroscope employing the hybrid Raman lasers can be implicitly improved 10 times. Due to the better high-frequency response, the sensitivity is not limited by the durations of Raman pulses. This work is important for improving the performance of atom-interferometer-based measurements. PMID:26906364

  11. Passive long range acousto-optic sensor

    NASA Astrophysics Data System (ADS)

    Slater, Dan

    2006-08-01

    Alexander Graham Bell's photophone of 1880 was a simple free space optical communication device that used the sun to illuminate a reflective acoustic diaphragm. A selenium photocell located 213 m (700 ft) away converted the acoustically modulated light beam back into sound. A variation of the photophone is presented here that uses naturally formed free space acousto-optic communications links to provide passive multichannel long range acoustic sensing. This system, called RAS (remote acoustic sensor), functions as a long range microphone with a demonstrated range in excess of 40 km (25 miles).

  12. High-frequency acousto-optic effects in Bragg reflectors.

    PubMed

    Farmer, D J; Akimov, A V; Gippius, N A; Bailey, J; Sharp, J S; Kent, A J

    2014-06-16

    Picosecond acoustic interferometry was used to study the acousto-optic properties of a distributed Bragg reflector (DBR) manufactured from two immiscible polymers (cellulose acetate and polyvinylcarbyzole). Picosecond strain pulses were injected into the structure and changes in its reflectance were monitored as a function of time. The reflectance exhibited single-frequency harmonic oscillations as the strain pulse traversed the DBR. A transfer matrix method was used to model the reflectance of the DBR in response to interface modulation and photo-elastic effects. This work shows that photo-elastic effects can account for the acousto-optic response of DBRs with acoustically matched layers. PMID:24977613

  13. FPGA-based phase control of acousto-optic modulator Fourier synthesis system through gradient descent phase-locking algorithm.

    PubMed

    Underwood, Kenneth J; Jones, Andrew M; Gopinath, Juliet T

    2015-06-20

    We present a new application of the stochastic parallel gradient descent (SPGD) algorithm to fast active phase control in a Fourier synthesis system. Pulses (4.9 ns) with an 80 MHz repetition rate are generated by feedback from a single phase-sensitive metric. Phase control is applied via fast current modulation of a tapered amplifier using an SPGD algorithm realized on a field-programmable gate array (FPGA). The waveforms are maintained by constant active feedback from the FPGA. We also discuss the extension of this technique to many more semiconductor laser emitters in a diode laser array. PMID:26193004

  14. Simple Digital Feed-Forward Circuit to Compensate for AOM Thermal Lensing

    NASA Astrophysics Data System (ADS)

    Hill, Joshua; Aman, James; Killian, Thomas; Neutral Experiment Team

    2016-05-01

    I demonstrate a simple digital feed-forward circuit which, when combined with two-frequency radio frequency (RF) electronics, maintains constant total RF power driving an acousto-optic modulator (AOM). Consistency in total power is desirable to mitigate thermal lensing effects that otherwise displace and misshape the laser beam when the primary frequency drive RF power is changed to, for example, alter the laser power in a diffracted beam. The Arduino-based feed-forward circuit is cost-effective, quick to implement, and easily modified.

  15. Acousto-optic laser projection systems for displaying TV information

    NASA Astrophysics Data System (ADS)

    Gulyaev, Yu V.; Kazaryan, M. A.; Mokrushin, Yu M.; Shakin, O. V.

    2015-04-01

    This review addresses various approaches to television projection imaging on large screens using lasers. Results are presented of theoretical and experimental studies of an acousto-optic projection system operating on the principle of projecting an image of an entire amplitude-modulated television line in a single laser pulse. We consider characteristic features of image formation in such a system and the requirements for its individual components. Particular attention is paid to nonlinear distortions of the image signal, which show up most severely at low modulation signal frequencies. We discuss the feasibility of improving the process efficiency and image quality using acousto-optic modulators and pulsed lasers. Real-time projectors with pulsed line imaging can be used for controlling high-intensity laser radiation.

  16. Small acousto-optic modulation for active mode locking in the iodine photodissociation laser and the effect of supplementary saturable absorber

    SciTech Connect

    Kim, Y.S.; Lee, S.S.

    1985-02-01

    Active, passive, and active--passive mode locking of the iodine photodissociation laser are investigated. The peak-to-background ratio (PBR) of the acousto-optically mode-locked pulse is 85% for rf power of 5 W. Passive mode locking using BDN dye gives PBR of 75% and has inferior reproducibility. The active--passive mode locking using the two methods simultaneously is useful for the pressure broadened iodine laser line and gives a PBR of 91%. In this case the rf power required for complete mode locking is calculated to be 7 W which is much less than the required power of 11 W in using active mode locking alone.

  17. Acousto-optical/Magneto-optical Correlator Or Convolver

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang; Davis, Jeffrey A.

    1989-01-01

    Experimental system demonstrates optical processing of multiple channels of binary signals. One input channel contains signal that varies with time and applied to one-dimensional acousto-optical cell. Other input channel contains two-dimensional pattern that is stationary or can vary with time and applied to magneto-optical spatial light modulator. Output is time-varying correlation or convolution of first input with one of rows in second input.

  18. Systolic acousto-optic binary convolver

    SciTech Connect

    Guilfoyle, P.S.

    1984-01-01

    A novel high speed array processing optical architecture is described. A multichannel acousto-optic binary convolver is architecturally configured as a systolic array processor. The architecture provides a high speed means of matrix/vector multiplications using the digital multiplication via an analog convolution algorithm. This algorithm and a systolic acousto-optic implementation permit the speed of optics to be combined with the accuracy of digital computation. 15 references.

  19. Polarization-independent operation of an acousto-optical device at the transmit end of a single-laser transmission system using self-heterodyning

    NASA Astrophysics Data System (ADS)

    Olivier, L.; Rocks, M.

    1991-03-01

    This paper describes the way in which a new integrated acousto-optical LiNbO 3 device combining the three functions of an electro-optical phase modulator, an acousto-optical TE/TM or TM/TE mode converter and an acousto-optical frequency shifter can be operated in a polarization-independent manner as a transmitter unit in a single-laser transmission system using self-heterodyning.

  20. Real-time polarization mode dispersion monitoring system for a multiple-erbium-doped fiber amplifier, dense wavelength division multiplexing optical fiber transmission by amplified spontaneous emission modulation and acousto-optic tunable fiber scanning techniques.

    PubMed

    Tseng, Bao-Jang; Tarn, Chen-Wen

    2009-03-01

    Without interruption or affecting the transmission of ordinary payload channels, we propose a real time polarization mode dispersion (PMD) monitoring system for long-haul, multiple erbium-doped fiber amplifier (EDFA), dense wavelength division multiplexing (DWDM) optical fiber transmission using modulated amplified spontaneous emission (ASE) of one of the EDFAs as the supervisory (SV) signal source. An acousto-optic tunable filter (AOTF) at the receiver side is adopted to scan the spectrum of the transmitted ASE SV signal. Using the fixed-analyzer method, PMDs of different wavelength bands that range from 1545 to 1580 nm of a DWDM fiber-optic communication system can be found by adaptively changing the radio frequency of the AOTF. The resolution and the measuring range of the proposed monitoring system can be significantly improved by cascading the AOTFs at the receiver side. PMID:19252622

  1. Acousto-optic spectrometer for radio astronomy

    NASA Technical Reports Server (NTRS)

    Chin, G.; Buhl, D.; Florez, J. M.

    1980-01-01

    A prototype acousto-optic spectrometer which uses a discrete bulk acoustic wave Itek Bragg cell, 5 mW Helium Neon laser, and a 1024 element Reticon charge coupled photodiode array is described. The analog signals from the photodiode array are digitized, added, and stored in a very high speed custom built multiplexer board which allows synchronous detection of weak signals to be performed. The experiment is controlled and the data are displayed and stored with an LSI-2 microcomputer system with dual floppy discs. The performance of the prototype acousto-optic spectrometer obtained from initial tests is reported.

  2. Quasi-collinear tunable acousto-optic paratellurite crystal filters for wavelength division multiplexing and optical channel selection

    SciTech Connect

    Molchanov, V Ya; Makarov, O Yu; Voloshinov, V B

    2009-04-30

    Quasi-collinear acousto-optic interaction is studied in acoustically and optically anisotropic paratellurite crystals. The possible applications of this interaction in acousto-optic tunable filters with a high spectral resolution are discussed. Different modifications of devices are compared and variants of devices intended for processing light beams and selection of light signals in fibreoptic communication systems with wavelength division multiplexing (WDM) at {lambda} {approx_equal} 1550 nm are considered. (light modulation)

  3. Growth of high quality mercurous halide single crystals by physical vapor transport method for AOM and radiation detection applications

    NASA Astrophysics Data System (ADS)

    Amarasinghe, Priyanthi M.; Kim, Joo-Soo; Chen, Henry; Trivedi, Sudhir; Qadri, Syed B.; Soos, Jolanta; Diestler, Mark; Zhang, Dajie; Gupta, Neelam; Jensen, Janet L.; Jensen, James

    2016-09-01

    Single crystals of mercurous halide were grown by physical vapor transport method (PVT). The orientation and the crystalline quality of the grown crystals were determined using high resolution x-ray diffraction (HRXRD) technique. The full width at half maximum (FWHM) of the grown mercurous bromide crystals was measured to be 0.13 degrees for (004) reflection, which is the best that has been achieved so far for PVT grown mercurous halide single crystals. The extended defects of the crystals were also analyzed using high resolution x-ray diffraction topography. Preliminary studies were carried out to evaluate the performance of the crystals on acousto-optic modulator (AOM) and gamma-ray detector applications. The results indicate the grown mercurous halide crystals are excellent materials for acousto-optic modulator device fabrication. The diffraction efficiencies of the fabricated AOM device with 1152 and 1523 nm wavelength lasers polarizing parallel to the acoustic wave were found to be 35% and 28%, respectively. The results also indicate the grown crystals are a promising material for gamma-ray detector application with a very high energy resolution of 1.86% FWHM.

  4. Acousto-optical spectrometers' frequency performance stability

    NASA Astrophysics Data System (ADS)

    Ivanov, Sergei I.; Lavrov, Aleksandr P.; Molodyakov, Sergey A.; Saenko, Igor I.

    2004-02-01

    Performance characteristics of the acoutsto-optical spectrometers for some radioastronomical applications are discussed. The main attention is given to the long-term stability of the acousto-optical spectrometer's frequency characteristics. It is shown that a problem of the frequency scale thermal instabilities can be overcome by using the suitable correction, based on the proposed model of the frequency scale drifts. For the acousto-optical spectrometers under consideration a simple method of the frequency scale drifts correction by using the data from measuring of a single reference signal's frequency was developed and applied for correction of molecular lines observations data. More careful procedure for more exigent applications, such as pulsar timing, is considered.

  5. Experimental demonstration of remote, passive acousto-optic sensing.

    PubMed

    Antonelli, Lynn; Blackmon, Fletcher

    2004-12-01

    Passively detecting underwater sound from the air can allow aircraft and surface vessels to monitor the underwater acoustic environment. Experimental research into an optical hydrophone is being conducted for remote, aerial detection of underwater sound. A laser beam is directed onto the water surface to measure the velocity of the vibrations occurring as the underwater acoustic signal reaches the water surface. The acoustically generated surface vibrations modulate the phase of the laser beam. Sound detection occurs when the laser is reflected back towards the sensor. Therefore, laser alignment on the specularly reflecting water surface is critical. As the water surface moves, the laser beam is reflected away from the photodetector and no signal is obtained. One option to mitigate this problem is to continually steer the laser onto a spot on the water surface that provides a direct back-reflection. Results are presented from a laboratory test that investigates the feasibility of the acousto-optic sensor detection on hydrostatic and hydrodynamic surfaces using a laser Doppler vibrometer in combination with a laser-based, surface normal glint tracker for remotely detecting underwater sound. This paper outlines the acousto-optic sensor and tracker concepts and presents experimental results comparing sensor operation under various sea surface conditions. PMID:15658691

  6. The quantum acousto-optic effect in Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Bhattacherjee, Aranya B.

    2009-09-01

    We investigate the interaction between a single mode light field and an elongated cigar shaped Bose-Einstein condensate (BEC), subject to a temporal modulation of the trap frequency in the tight confinement direction. Under appropriate conditions, the longitudinal sound like waves (Faraday waves) in the direction of weak confinement acts as a dynamic diffraction grating for the incident light field analogous to the acousto-optic effect in classical optics. The change in the refractive index due to the periodic modulation of the BEC density is responsible for the acousto-optic effect. The dynamics is characterised by Bragg scattering of light from the matter wave Faraday grating and simultaneous Bragg scattering of the condensate atoms from the optical grating formed due to the interference between the incident light and the diffracted light fields. Varying the intensity of the incident laser beam we observe the transition from the acousto-optic effect regime to the atomic Bragg scattering regime, where Rabi oscillations between two momentum levels of the atoms are observed. We show that the acousto-optic effect is reduced as the atomic interaction is increased.

  7. Theoretical study of Fourier-transform acousto-optic imaging.

    PubMed

    Barjean, Kinia; Ramaz, François; Tualle, Jean-Michel

    2016-05-01

    We propose a full theoretical study of Fourier-transform acousto-optic imaging, which we recently introduced and experimentally assessed in [Opt. Lett.40, 705-708 (2015)OPLEDP0146-959210.1364/OL.40.000705] as an alternative to achieve axial resolution in acousto-optic imaging with a higher signal-to-noise ratio. PMID:27140883

  8. Display system employing acousto-optic tunable filter

    NASA Technical Reports Server (NTRS)

    Lambert, James L. (Inventor)

    1995-01-01

    An acousto-optic tunable filter (AOTF) is employed to generate a display by driving the AOTF with a RF electrical signal comprising modulated red, green, and blue video scan line signals and scanning the AOTF with a linearly polarized, pulsed light beam, resulting in encoding of color video columns (scan lines) of an input video image into vertical columns of the AOTF output beam. The AOTF is illuminated periodically as each acoustically-encoded scan line fills the cell aperture of the AOTF. A polarizing beam splitter removes the unused first order beam component of the AOTF output and, if desired, overlays a real world scene on the output plane. Resolutions as high as 30,000 lines are possible, providing holographic display capability.

  9. Display system employing acousto-optic tunable filter

    NASA Technical Reports Server (NTRS)

    Lambert, James L. (Inventor)

    1993-01-01

    An acousto-optic tunable filter (AOTF) is employed to generate a display by driving the AOTF with a RF electrical signal comprising modulated red, green, and blue video scan line signals and scanning the AOTF with a linearly polarized, pulsed light beam, resulting in encoding of color video columns (scan lines) of an input video image into vertical columns of the AOTF output beam. The AOTF is illuminated periodically as each acoustically-encoded scan line fills the cell aperture of the AOTF. A polarizing beam splitter removes the unused first order beam component of the AOTF output and, if desired, overlays a real world scene on the output plane. Resolutions as high as 30,000 lines are possible, providing holographic display capability.

  10. Wideband acousto-optic correlator for an ESM receiver upgrade

    NASA Astrophysics Data System (ADS)

    Anderson, C.; Dorsett, A.; Tepper, S.; Zari, M.; Filipov, A.; Adler, E.; Pellegrino, J.

    An acousto-optic (AO) correlator is being constructed that offers a small, lightweight solution to detecting and analyzing wide-bandwidth, spread-spectrum signals. The processor is being inserted into an existing electronic support measure (ESM) test-bed under the Defense Advanced Research Projects Agency (DARPA) Transition of Optical Processors into Systems (TOPS) program. The correlator has a processing bandwidth of 500 MHz and will be used to detect direct-sequence, phase-modulated signals, frequency-hopped signals, chirps, and impulses. A description of the processor is provided along with experimental results obtained from an interim developmental breadboard. Subsequent digital processing, which includes nonlinear detection and Fourier transformation, is used to determine center frequencies, bandwidths, and band shape. Theoretical descriptions of the post-processing are provided.

  11. Wideband acousto-optic correlator for an ESM receiver upgrade

    NASA Astrophysics Data System (ADS)

    Anderson, Christopher S.; Dorsett, Anne-Marie; Tepper, Sandi K.; Zari, Michael C.; Filipov, Andree N.; Adler, Eric D.; Pellegrino, John M.

    1993-09-01

    An acousto-optic (AO) correlator is being constructed that offers a small, lightweight solution to detecting and analyzing wide-bandwidth, spread-spectrum signals. The processor is being inserted into an existing electronic support measure (ESM) test-bed under the Defense Advanced Research Projects Agency (DARPA) Transition of Optical Processors into Systems (TOPS) program. The correlator has a processing bandwidth of 500 MHz and will be used to detect direct-sequence, phase-modulated signals, frequency-hopped signals, chirps, and impulses. A description of the processor is provided along with experimental results obtained from an interim developmental breadboard. Subsequent digital processing, which includes nonlinear detection and Fourier transformation, is used to determine center frequencies, bandwidths, and band shape. Theoretical descriptions of the post-processing are provided and simulations results are discussed.

  12. Fast spatial beam shaping by acousto-optic diffraction for 3D non-linear microscopy.

    PubMed

    Akemann, Walther; Léger, Jean-François; Ventalon, Cathie; Mathieu, Benjamin; Dieudonné, Stéphane; Bourdieu, Laurent

    2015-11-01

    Acousto-optic deflection (AOD) devices offer unprecedented fast control of the entire spatial structure of light beams, most notably their phase. AOD light modulation of ultra-short laser pulses, however, is not straightforward to implement because of intrinsic chromatic dispersion and non-stationarity of acousto-optic diffraction. While schemes exist to compensate chromatic dispersion, non-stationarity remains an obstacle. In this work we demonstrate an efficient AOD light modulator for stable phase modulation using time-locked generation of frequency-modulated acoustic waves at the full repetition rate of a high power laser pulse amplifier of 80 kHz. We establish the non-local relationship between the optical phase and the generating acoustic frequency function and verify the system for temporal stability, phase accuracy and generation of non-linear two-dimensional phase functions. PMID:26561090

  13. Intracavity KTP OPO pumped by a doubly Q-switched laser with AOM and a monolayer graphene saturable abosorber

    NASA Astrophysics Data System (ADS)

    Qiao, Junpeng; Zhao, Jia; Yang, Kejian; Zhao, Shengzhi; Li, Guiqiu; Li, Dechun; Li, Tao; Qiao, Wenchao; Chu, Hongwei

    2015-12-01

    An intracavity KTiOPO4 (KTP) optical parametric oscillator (IOPO) pumped by a doubly Q-switched YVO4/Nd:YVO4 laser with an acousto-optic modulator (AOM) and a monolayer graphene saturable absorber has been realized for the first time. The average output power, the pulse duration, single pulse energy and the peak power of signal light versus incident pump power have been measured. At an incident pump power of 11.7 W and an AOM repetition rate of 10 kHz, the shortest pulse duration of 1.24 ns was obtained, corresponding to a single pulse energy of 9.5 μJ and a peak power of 7.9 kW. In comparison, the doubly IOPO (DIOPO) pumped by doubly Q-switched laser with AOM and graphene saturable absorber can generate pulses with narrower pulse width and higher peak power than the singly IOPO (SIOPO) pumped only by AOM Q-switched laser.

  14. Acousto-optically tuned isotopic CO{sub 2} lasers for long-range differential absorption LIDAR

    SciTech Connect

    Thompson, D.C.; Busch, G.E.; Hewitt, C.J.; Remelius, D.K.; Shimada, Tsutomu; Strauss, C.E.M.; Wilson, C.W.

    1998-12-01

    The authors are developing 2--100 kHz repetition rate CO{sub 2} lasers with milliJoule pulse energies, rapid acousto-optic tuning and isotopic gas mixes, for Differential Absorption LIDAR (DIAL) applications. The authors explain the tuning method, which uses a pair of acousto-optic modulators and is capable of random access to CO{sub 2} laser lines at rates of 100 kHz or more. The laser system is also described, and they report on performance with both normal and isotopic gas mixes.

  15. Wide-aperture diffraction of unpolarised radiation in a system of two acousto-optic filters

    SciTech Connect

    Magdich, L N; Yushkov, K B; Voloshinov, V B

    2009-04-30

    Light diffraction is studied in two tandem acousto-optic cells filtering unpolarised radiation with a wide angular spectrum. It is shown that the side lobes of the ultrasonic radiation pattern of a piezoelectric transducer produce side diffraction intensity maxima at the output of the system consisting of two filters. Diffraction in paratellurite filters is studied experimentally at 1.06 {mu}m. (light modulation)

  16. An acousto-optical imaging spectrometer for astrophysical measurements

    NASA Astrophysics Data System (ADS)

    Anikin, S. P.; Esipov, V. F.; Molchanov, V. Ya.; Tatarnikov, A. M.; Yushkov, K. B.

    2016-07-01

    An optical scheme of an acousto-optical imaging spectrometer for observing extended astrophysical objects with line emission spectra is proposed. The use of an additional prism with a specified angular dispersion makes it possible to separate images of an extended object at different emission lines and images generated by minor maxima of the acousto-optical filter transmission function. A prototype of the imaging spectrometer has been designed.

  17. Holographic video display based on guided-wave acousto-optic devices

    NASA Astrophysics Data System (ADS)

    Smalley, Daniel E.; Smithwick, Quinn Y. J.; Bove, V. Michael, Jr.

    2007-02-01

    We introduce a new holo-video display architecture ("Mark III") developed at the MIT Media Laboratory. The goal of the Mark III project is to reduce the cost and size of a holo-video display, making it into an inexpensive peripheral to a standard desktop PC or game machine which can be driven by standard graphics chips. Our new system is based on lithium niobate guided-wave acousto-optic devices, which give twenty or more times the bandwidth of the tellurium dioxide bulk-wave acousto-optic modulators of our previous displays. The novel display architecture is particularly designed to eliminate the high-speed horizontal scanning mechanism that has traditionally limited the scalability of Scophony- style video displays. We describe the system architecture and the guided-wave device, explain how it is driven by a graphics chip, and present some early results.

  18. Acousto-optical properties of metamaterials

    NASA Astrophysics Data System (ADS)

    Pustovoit, V. I.

    2016-02-01

    The possibility of the effective use of metamaterials in acousto-optics is demonstrated. It is shown that photoelastic constants that determine a change in the dielectric constant of a heterogeneous medium under the action of a sound wave can significantly exceed the corresponding constants for conventional crystals. We have analysed the mechanisms of the dielectric constant variation in a heterogeneous medium consisting of nanoparticles in the form of ellipsoids and have found explicitly the values of the photoelastic constants. It is shown that the mechanism of the dielectric constant variation in a longitudinal sound wave is reduced to a change in the local concentration of nanoparticles in the bulk and in a transverse acoustic wave - to a local rotation of space-oriented nanoellipsoids. It is also shown that the use of metamedia with a nonuniform distribution of nanoparticles provides a unique opportunity for designing qualitatively new instruments and devices that cannot be produced on the basis of conventional crystals. It is noted that metamaterials open ample opportunities for creating devices of the IR region of the spectrum due to the absence of restrictions on the size of such media.

  19. Investigation of acoustic beam reflection influence on the collinear acousto-optic interaction characteristics.

    PubMed

    Mantsevich, S N

    2016-08-01

    Significant part of acousto-optic devices apply the acoustic beam reflection to arouse the desired type of acoustic mode propagating along the required direction in crystal. The influence of acoustic beam reflection process on the ultrasound field structure in the acousto-optic cell and the collinear acousto-optic diffraction characteristics is examined in this paper. The investigation is carried on the example of the collinear acousto-optic filter fabricated on the base of calcium molybdate crystal. It is shown that the reflection process changes the acoustic field structure and affects the acousto-optic filter transmission function shape and diffraction efficiency. PMID:27153373

  20. Nonreciprocal acousto-optical effect in planar waveguides

    SciTech Connect

    Nanii, Oleg E

    2000-03-31

    The amplitude nonreciprocal effect in planar waveguides during the interaction of waveguide optical modes with a travelling surface acoustic wave was calculated. The possibility of constructing an optical isolator (circulator) by using collinear acousto-optical diffraction with conversion of the type of waveguide mode is demonstrated. (laser applications and other topics in quantum electronics)

  1. Acousto-optical confirmation of the localized wave phenomena

    SciTech Connect

    Lewis, D.K.

    1992-09-09

    An acousto-optical measurement method is described which was used to conduct proof of principle experiments for a novel acoustic pulse system. The pulse theory, the Localized Wave pulse, is discussed and the system explained and described. The results of the experiments confirm the Localized Wave theory.

  2. Guided-wave acousto-optic devices for space applications

    NASA Astrophysics Data System (ADS)

    Ciminelli, C.; Peluso, F.; Armenise, M. N.

    2005-09-01

    Production of high- performance and low-cost new devices to be used in space applications is strongly required due to the remarkable development of innovative technologies in the last few years. Guided-wave optoelectronics technologies, including integrated optics, acousto-optics and electro-optics can provide some significant benefits to the space applications. In particular, they can overcome the intrinsic limits of the conventional technologies improving also the cost/performance figures, and enabling new services. Earth observation, telecommunications, radar surveillance and navigation control are the main space areas where guided-wave devices can contribute significantly. In this paper, after some general considerations on the potential of optoelectronics for space, on the use of acousto-optic guided-wave devices, a brief description of the acousto-optic interaction is given. Some functional devices reported in literature having significant potential impact in space applications are described with the aim of highlighting the main features of the acousto-optic technology. The performance limits of guided-wave devices for space applications are also shortly discussed.

  3. Acousto-optic deflector of depolarized laser radiation

    NASA Astrophysics Data System (ADS)

    Antonov, S. N.

    2016-01-01

    An original acousto-optic deflector is based on the anisotropic diffraction in the paratellurite crystal. The deflector is characterized by a relatively high diffraction efficiency for depolarized laser radiation. The deflector consists of two sequential acousto-optic cells. Each cell deflects one of the orthogonally polarized components of the originally depolarized radiation. The first and second cells scan the low- and highfrequency parts of the angular interval, respectively. The simultaneous and independent operation of the cells makes it possible to use the entire optical (laser) power. A frequency band of 32 MHz is almost reached for depolarized radiation with a wavelength of 1.06 µm and the absolute angular interval is 50 mrad at a total efficiency of no less than 70%.

  4. Acousto-optic processor for distributed interactive video system

    NASA Astrophysics Data System (ADS)

    Volner, Rudolf; Ticha, Dasa

    1999-12-01

    This article describes information network - a backbone network structure, a video switch topology and acousto- optics processor applications - AOP. Cable is a natural network for carrying high-capacity, bandwidth - in tensity information. In the age of analog program signals, cable capacity was a natural transmission media for broadcasting of color TV and high-fidelity stereo sound programs. In the new digital program signal age, cable high capacity is a natural network for carrying interactive computer-based, data-multimedia programs.

  5. Ultrafast acousto-optic mode conversion in optically birefringent ferroelectrics

    NASA Astrophysics Data System (ADS)

    Lejman, Mariusz; Vaudel, Gwenaelle; Infante, Ingrid C.; Chaban, Ievgeniia; Pezeril, Thomas; Edely, Mathieu; Nataf, Guillaume F.; Guennou, Mael; Kreisel, Jens; Gusev, Vitalyi E.; Dkhil, Brahim; Ruello, Pascal

    2016-08-01

    The ability to generate efficient giga-terahertz coherent acoustic phonons with femtosecond laser makes acousto-optics a promising candidate for ultrafast light processing, which faces electronic device limits intrinsic to complementary metal oxide semiconductor technology. Modern acousto-optic devices, including optical mode conversion process between ordinary and extraordinary light waves (and vice versa), remain limited to the megahertz range. Here, using coherent acoustic waves generated at tens of gigahertz frequency by a femtosecond laser pulse, we reveal the mode conversion process and show its efficiency in ferroelectric materials such as BiFeO3 and LiNbO3. Further to the experimental evidence, we provide a complete theoretical support to this all-optical ultrafast mechanism mediated by acousto-optic interaction. By allowing the manipulation of light polarization with gigahertz coherent acoustic phonons, our results provide a novel route for the development of next-generation photonic-based devices and highlight new capabilities in using ferroelectrics in modern photonics.

  6. Ultrafast acousto-optic mode conversion in optically birefringent ferroelectrics.

    PubMed

    Lejman, Mariusz; Vaudel, Gwenaelle; Infante, Ingrid C; Chaban, Ievgeniia; Pezeril, Thomas; Edely, Mathieu; Nataf, Guillaume F; Guennou, Mael; Kreisel, Jens; Gusev, Vitalyi E; Dkhil, Brahim; Ruello, Pascal

    2016-01-01

    The ability to generate efficient giga-terahertz coherent acoustic phonons with femtosecond laser makes acousto-optics a promising candidate for ultrafast light processing, which faces electronic device limits intrinsic to complementary metal oxide semiconductor technology. Modern acousto-optic devices, including optical mode conversion process between ordinary and extraordinary light waves (and vice versa), remain limited to the megahertz range. Here, using coherent acoustic waves generated at tens of gigahertz frequency by a femtosecond laser pulse, we reveal the mode conversion process and show its efficiency in ferroelectric materials such as BiFeO3 and LiNbO3. Further to the experimental evidence, we provide a complete theoretical support to this all-optical ultrafast mechanism mediated by acousto-optic interaction. By allowing the manipulation of light polarization with gigahertz coherent acoustic phonons, our results provide a novel route for the development of next-generation photonic-based devices and highlight new capabilities in using ferroelectrics in modern photonics. PMID:27492493

  7. Ultrafast acousto-optic mode conversion in optically birefringent ferroelectrics

    PubMed Central

    Lejman, Mariusz; Vaudel, Gwenaelle; Infante, Ingrid C.; Chaban, Ievgeniia; Pezeril, Thomas; Edely, Mathieu; Nataf, Guillaume F.; Guennou, Mael; Kreisel, Jens; Gusev, Vitalyi E.; Dkhil, Brahim; Ruello, Pascal

    2016-01-01

    The ability to generate efficient giga–terahertz coherent acoustic phonons with femtosecond laser makes acousto-optics a promising candidate for ultrafast light processing, which faces electronic device limits intrinsic to complementary metal oxide semiconductor technology. Modern acousto-optic devices, including optical mode conversion process between ordinary and extraordinary light waves (and vice versa), remain limited to the megahertz range. Here, using coherent acoustic waves generated at tens of gigahertz frequency by a femtosecond laser pulse, we reveal the mode conversion process and show its efficiency in ferroelectric materials such as BiFeO3 and LiNbO3. Further to the experimental evidence, we provide a complete theoretical support to this all-optical ultrafast mechanism mediated by acousto-optic interaction. By allowing the manipulation of light polarization with gigahertz coherent acoustic phonons, our results provide a novel route for the development of next-generation photonic-based devices and highlight new capabilities in using ferroelectrics in modern photonics. PMID:27492493

  8. Triple product acousto-optical processor for the astrophysical applications

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Alexandre S.; Hanessian de la Garza, Ana Virginia; Chavushyan, Vahram; Campos Acosta, Joaquin

    2012-10-01

    This processor is oriented to studies in the extra-galactic astronomy as well as to searching the extra-solar planets, so that algorithm of the space-and-time integrating is desirable for a wideband spectrum analysis with an improved resolution. It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this algorithm is based on exploiting the chirp Z - transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of designing the triple product acousto-optical processor in frames of the astrophysical instrumentation is presented.

  9. Bulk and integrated acousto-optic spectrometers for molecular astronomy with heterodyne spectrometers

    NASA Technical Reports Server (NTRS)

    Chin, G.; Buhl, D.; Florez, J. M.

    1981-01-01

    A survey of acousto-optic spectrometers for molecular astronomy is presented, noting a technique of combining the acoustic bending of a collimated coherent light beam with a Bragg cell followed by an array of sensitive photodetectors. This acousto-optic spectrometer has a large bandwidth, a large number of channels, high resolution, and is energy efficient. Receiver development has concentrated on high-frequency heterodyne systems for the study of the chemical composition of the interstellar medium. RF spectrometers employing acousto-optic diffraction cells are described. Acousto-optic techniques have been suggested for applications to electronic warfare, electronic countermeasures and electronic support systems. Plans to use integrated optics for the further miniaturization of acousto-optic spectrometers are described. Bulk acousto-optic spectrometers with 300 MHz and 1 GHz bandwidths are being developed for use in the back-end of high-frequency heterodyne receivers for astronomical research.

  10. Wide-band acousto-optic deflectors for large field of view two-photon microscope.

    PubMed

    Jiang, Runhua; Zhou, Zhenqiao; Lv, Xiaohua; Zeng, Shaoqun

    2012-04-01

    Acousto-optic deflector (AOD) is an attractive scanner for two-photon microscopy because it can provide fast and versatile laser scanning and does not involve any mechanical movements. However, due to the small scan range of available AOD, the field of view (FOV) of the AOD-based microscope is typically smaller than that of the conventional galvanometer-based microscope. Here, we developed a novel wide-band AOD to enlarge the scan angle. Considering the maximum acceptable acoustic attenuation in the acousto-optic crystal, relatively lower operating frequencies and moderate aperture were adopted. The custom AOD was able to provide 60 MHz 3-dB bandwidth and 80% peak diffraction efficiency at 840 nm wavelength. Based on a pair of such AOD, a large FOV two-photon microscope was built with a FOV up to 418.5 μm (40× objective). The spatiotemporal dispersion was compensated simultaneously with a single custom-made prism. By means of dynamic power modulation, the variation of laser intensity within the FOV was reduced below 5%. The lateral and axial resolution of the system were 0.58-2.12 μm and 2.17-3.07 μm, respectively. Pollen grain images acquired by this system were presented to demonstrate the imaging capability at different positions across the entire FOV. PMID:22559541

  11. Investigation of a mercurous chloride acousto-optic cell based on longitudinal acoustic mode.

    PubMed

    Gupta, Neelam

    2009-03-01

    A number of spectral imagers using acousto-optic tunable filters (AOTFs) operating from the UV to the longwave infrared (LWIR) using KDP, MgF(2), TeO(2), and Tl(3)AsSe(3) crystals to cover different spectral regions have been developed. In the LWIR there is a lack of high quality acousto-optic (AO) materials. Mercurous halide (Hg(2)Cl(2) and Hg(2)Br(2)) crystals are highly anisotropic with a high AO figure of merit due to slow acoustic velocities and high photoelastic constants and are transparent over a wide spectral region from 0.35 to 20 mum for Hg(2)Cl(2) and from 0.4 to 30 mum for Hg(2)Br(2). AO modulators, deflectors, and AOTFs based on these crystals can operate over a wide spectral range. Single crystals of these materials are being grown and some prototype devices have been fabricated. Results are presented from device characterization for an AO cell fabricated in Hg(2)Cl(2) based on longitudinal acoustic mode propagation. This device was very useful in demonstrating the AO interaction as well as soundness of the transducer bonding technique. Acoustic phase velocity is calculated and measured, diffraction efficiency is obtained from experiments, and the AO figure of merit of the sample is evaluated. PMID:19252608

  12. Bulk and integrated acousto-optic spectrometers for radio astronomy

    NASA Technical Reports Server (NTRS)

    Chin, G.; Buhl, D.; Florez, J. M.

    1981-01-01

    The development of sensitive heterodyne receivers (front end) in the centimeter and millimeter range, and the construction of sensitive RF spectrometers (back end) enable the spectral lines of interstellar molecules to be detected and identified. A technique was developed which combines acoustic bending of a collimated coherent light beam by a Bragg cell followed by detection by a sensitive array of photodetectors (thus forming an RF acousto-optic spectrometer (AOS). An AOS has wide bandwidth, large number of channels, and high resolution, and is compact, lightweight, and energy efficient. The thrust of receiver development is towards high frequency heterodyne systems, particularly in the millimeter, submillimeter, far infrared, and 10 micron spectral ranges.

  13. An acousto-optic sensor based on resonance grating waveguide structure

    PubMed Central

    Xie, Antonio Jou; Song, Fuchuan; Seo, Sang-Woo

    2014-01-01

    This paper presents an acousto-optic (AO) sensor based on resonance grating waveguide structure. The sensor is fabricated using elastic polymer materials to achieve a good sensitivity to ultrasound pressure waves. Ultrasound pressure waves modify the structural parameters of the sensor and result in the optical resonance shift of the sensor. This converts into a light intensity modulation. A commercial ultrasound transducer at 20 MHz is used to characterize a fabricated sensor and detection sensitivity at different optical source wavelength within a resonance spectrum is investigated. Practical use of the sensor at a fixed optical source wavelength is presented. Ultimately, the geometry of the planar sensor structure is suitable for two-dimensional, optical pressure imaging applications such as pressure wave detection and mapping, and ultrasound imaging. PMID:25045203

  14. Guided-wave multichannel acousto-optic devices based on collinear wave propagation

    NASA Astrophysics Data System (ADS)

    Proklov, Valery V.; Korablev, E. M.

    1992-11-01

    Recently, there appeared in acousto-optics (AO) a tendency to develop the optical information processing technology based on AO spatial light modulators, which are very promising in relation to very fast analog signal processing and algebraic data processing with digital accuracy. The best widely distinguished way to win many other marketing counterparts lies in the performance of AO interactions in guided wave structures with highly developed planar technology. In contrast to numerous developments devoted to guided wave AO devices the collinear ones facilitate multichannel or 2-D-devices to increase their throughput and processing gain. We discuss general backgrounds of the guided wave AO devices, especially in the case of the collinear wave propagations. Some applications similar to the multichannel collinear AO Bragg cell on LiNbO for 2-D-beam scanning, AO spectrum analysis, 2-D- Fourier signal processing, frequency multiplexing/demultiplexing, and digital vector-matrix multiplication are presented.

  15. Ultrasonic power measurement system based on acousto-optic interaction.

    PubMed

    He, Liping; Zhu, Fulong; Chen, Yanming; Duan, Ke; Lin, Xinxin; Pan, Yongjun; Tao, Jiaquan

    2016-05-01

    Ultrasonic waves are widely used, with applications including the medical, military, and chemical fields. However, there are currently no effective methods for ultrasonic power measurement. Previously, ultrasonic power measurement has been reliant on mechanical methods such as hydrophones and radiation force balances. This paper deals with ultrasonic power measurement based on an unconventional method: acousto-optic interaction. Compared with mechanical methods, the optical method has a greater ability to resist interference and also has reduced environmental requirements. Therefore, this paper begins with an experimental determination of the acoustic power in water contained in a glass tank using a set of optical devices. Because the light intensity of the diffraction image generated by acousto-optic interaction contains the required ultrasonic power information, specific software was written to extract the light intensity information from the image through a combination of filtering, binarization, contour extraction, and other image processing operations. The power value can then be obtained rapidly by processing the diffraction image using a computer. The results of this work show that the optical method offers advantages that include accuracy, speed, and a noncontact measurement method. PMID:27250458

  16. Ultrasonic power measurement system based on acousto-optic interaction

    NASA Astrophysics Data System (ADS)

    He, Liping; Zhu, Fulong; Chen, Yanming; Duan, Ke; Lin, Xinxin; Pan, Yongjun; Tao, Jiaquan

    2016-05-01

    Ultrasonic waves are widely used, with applications including the medical, military, and chemical fields. However, there are currently no effective methods for ultrasonic power measurement. Previously, ultrasonic power measurement has been reliant on mechanical methods such as hydrophones and radiation force balances. This paper deals with ultrasonic power measurement based on an unconventional method: acousto-optic interaction. Compared with mechanical methods, the optical method has a greater ability to resist interference and also has reduced environmental requirements. Therefore, this paper begins with an experimental determination of the acoustic power in water contained in a glass tank using a set of optical devices. Because the light intensity of the diffraction image generated by acousto-optic interaction contains the required ultrasonic power information, specific software was written to extract the light intensity information from the image through a combination of filtering, binarization, contour extraction, and other image processing operations. The power value can then be obtained rapidly by processing the diffraction image using a computer. The results of this work show that the optical method offers advantages that include accuracy, speed, and a noncontact measurement method.

  17. Effect of input phase modulation to a phase-sensitive optical amplifier.

    PubMed

    Li, Tian; Anderson, Brian E; Horrom, Travis; Jones, Kevin M; Lett, Paul D

    2016-08-22

    Many optical applications depend on amplitude modulating optical beams using devices such as acousto-optical modulators (AOMs) or optical choppers. Methods to add amplitude modulation (AM) often inadvertently impart phase modulation (PM) onto the light as well. While this PM is of no consequence to many phase-insensitive applications, phase-sensitive processes can be affected. Here we study the effects of input phase and amplitude modulation on the output of a quantum-noise limited phase-sensitive optical amplifier (PSA) realized in hot 85Rb vapor. We investigate the dependence of PM on AOM alignment and demonstrate a novel approach to quantifying PM by using the PSA as a diagnostic tool. We then use this method to measure the alignment-dependent PM of an optical chopper which arises due to diffraction effects as the chopper blade passes through the optical beam. PMID:27557263

  18. Collinear Acousto-Optical Transformation of Bessel Light Beams in Biaxial Gyrotropic Crystals

    NASA Astrophysics Data System (ADS)

    Belyi, V. N.; Kulak, G. V.; Krokh, G. V.; Shakin, O. V.

    2016-05-01

    The collinear acousto-optical transformation of Bessel light beams in biaxial gyrotropic crystals into two annular, internal conical refraction beams with orthogonal elliptical polarization is studied. It is found that the diffraction efficiency is maximal (~50-60%) for low ultrasound intensities and varies slightly with further increases in acoustic power. At high ultrasound intensities, the intensities of the transmitted and diffracted annular beams differ insignificantly. The possible use of this acousto-optical interaction for creating collinear tuneable narrow-band acousto-optical filters at low ultrasonic frequencies is demonstrated.

  19. Acousto-Optic Imaging Spectrometers for Mars Surface Science

    NASA Technical Reports Server (NTRS)

    Glenar, D. A.; Blaney, D. L.

    2000-01-01

    NASA's long term plan for Mars sample collection and return requires a highly streamlined approach for spectrally characterizing a landing site, documenting the mineralogical make-up of the site and guiding the collections of samples which represent the diversity of the site. Ideally, image data should be acquired at hundreds of VIS and IR wavelengths, in order to separately distinguish numerous anticipated species, using principal component analysis and linear unmixing. Cameras with bore-sighted point spectrometers can acquire spectra of isolated scene elements, but it requires 10(exp 2) to 10(exp 2) successive motions and precise relative pointing knowledge in order to create a single data cube which qualifies as a spectral map. These and other competing science objectives have to be accomplished within very short lander/rover operational lifetime (a few sols). True, 2-D imaging spectroscopy greatly speeds up the data acquisition process, since the spectra of all pixels in the scene are collected at once. This task can be accomplished with cameras that use electronically tunable acousto-optic tunable filters (AOTFs) as the optical tuning element. AOTFs made from TeO2 are now a mature technology, and operate at wavelengths from near-UV to about 5 microns. Because of incremental improvements in the last few years, present generation devices are rugged, radiation-hard and operate at temperatures down to at least 150K so they can be safely integrated into the ambient temperature optics of in-situ instruments such as planetary or small-body landers. They have been used for ground-based astronomy, and were also baselined for the ST-4 Champollion IR comet lander experiment (CIRCLE), prior to cancellation of the ST-4 mission last year. AIMS (for Acousto-optic Imaging spectrometer), is a prototype lander instrument which is being built at GSFC with support by the NASA OSS Advanced Technologies and Mission Studies, Mars Instrument Definition and Development Program (MIDP

  20. Electro-optic and acousto-optic laser beam scanners

    NASA Astrophysics Data System (ADS)

    Heberle, Johannes; Bechtold, Peter; Strauß, Johannes; Schmidt, Michael

    2016-03-01

    Electro-optical deflectors (EOD) and acousto-optical deflectors (AOD) are based on deflection of laser light within a solid state medium. As they do not contain any moving parts, they yield advantages compared to mechanical scanners which are conventionally used for laser beam deflection. Even for arbitrary scan paths high feed rates can be achieved. In this work the principles of operation and characteristic properties of EOD and AOD are presented. Additionally, a comparison to mirror based mechanical deflectors regarding deflection angles, speed and accuracy is made in terms of resolvable spots and the rate of resolvable spots. Especially, the latter one is up to one order of magnitude higher for EOD and AOD systems compared to conventional systems. Further characteristic properties such as response time, damage threshold, efficiency and beam distortions are discussed. Solid state laser beam deflectors are usually characterized by small deflection angles but high angular deflection velocities. As mechanical deflectors exhibit opposite properties an arrangement of a mechanical scanner combined with a solid state deflector provides a solution with the benefits of both systems. As ultrashort pulsed lasers with average power above 100 W and repetition rates in the MHz range have been available for several years this approach can be applied to fully exploit their capabilities. Thereby, pulse overlap can be reduced and by this means heat affected zones are prevented to provide proper processing results.

  1. Recent advance in application of acousto-optic tunable filters

    NASA Astrophysics Data System (ADS)

    Khansuvarov, Ruslan A.; Shakin, Oleg V.; Vaganov, Mikhail A.; Zhdanov, Arseniy Y.; Prokashev, Vadim N.

    2014-09-01

    This paper aims to inform those interested in the scientific work of a large group of scientists: workers of the Department of Electronics and Optical communications of St. Petersburg State University of Aerospace Instrumentation in collaboration with workers of the Department of Quantum Electronics of St. Petersburg State Technical University in the area of researches and development of acousto-optic tunable filters (AOTF). Paper discusses the important features of the AOTF structure and their parameters that affect its work, such as: spectral range of optical radiation, spectral resolution, active aperture of the optical radiation, optical transmission of the working spectral range, optical radiation polarization (linear, circular or arbitrary) , diffraction efficiency, contrast, distortion of the optical radiation's front, frequency range of elastic waves, switching time, maximum electric control power, impedance. Also the AOTF using is considered: AOTF's implications for control of laser radiation, AOTF's application to determine the counterfeit money. The last part of the report focuses on materials that act as antireflection thin films. Spectral characteristics of "clean" and enlightened substrates of ZnSe and Ge are shown. As seen from the examples in the report, antireflection thin films increase transmittance of optical elements.

  2. Materials for imaging acousto-optic tunable filters

    NASA Astrophysics Data System (ADS)

    Gupta, Neelam

    2014-05-01

    Research and development of robust compact hyperspectral imagers that can acquire both spectral and spatial features from a scene of interest is of utmost importance for standoff detection of targets as well as chemical and biological agents and backgrounds. Hyperspectral imagers can acquire images with a large number of narrow spectral bands and take advantage of the characteristic spectral signatures of different materials making up the scene. At the Army Research Laboratory (ARL), we are developing hyperspectral imagers based on acousto-optic tunable filters (AOTFs) that can provide adaptive no-moving-parts imagers from the ultraviolet (UV) to the long wave infrared (LWIR) to acquire a two-dimensional spectral image and build up a two-dimensional image cube as a function of time instead of using traditional grating or prism based approach that requires relative motion between sensor and scene. Here, we will review the development of different imaging AOTFs operating from the UV to the LWIR based on a variety of birefringent materials and include the spectral imaging carried out with these filters including both with single and double piezoelectric transducers. We will also include the theoretical background needed to carry out the filter design and discuss development of mercurous halide crystals that can be used to develop AOTFs operating over a wide spectral region from the visible to the LWIR.

  3. Double tungsten coil atomic absorption spectrometer based on an acousto-optic tunable filter

    NASA Astrophysics Data System (ADS)

    Jora, M. Z.; Nóbrega, J. A.; Rohwedder, J. J. R.; Pasquini, C.

    2015-01-01

    An atomic absorption spectrometer based on a quartz acousto-optic tunable filter (AOTF) monochromator operating in the 271-453 nm range, is described. The instrument was tailored to study the formation and evolution of electrothermal atomic cloud induced either by one or two tungsten coils. The spectrometer also includes a fast response programmable photomultiplier module for data acquisition, and a power supply capable of driving two parallel tungsten coils independently. The atomization cell herein described was manufactured in PTFE and presents a new design with reduced size. Synchronization between the instant of power delivering to start the atomization process and the detection was achieved, allowing for monitoring the atomization and thermal events synchronously and in real time. Absorption signals can be sampled at a rate of a few milliseconds, compatible with the fast phenomena that occur with electrothermal metallic atomizers. The instrument performance was preliminarily evaluated by monitoring the absorption of radiation of atomic clouds produced by standard solutions containing chromium or lead. Its quantitative performance was evaluated by using Cr aqueous solutions, resulting in detection limits as low as 0.24 μg L- 1, and a relative standard deviation of 3%.

  4. Transformation of phase dislocations under acousto-optic interaction of optical and acoustical Bessel beams

    NASA Astrophysics Data System (ADS)

    Belyi, V. N.; Khilo, P. A.; Kazak, N. S.; Khilo, N. A.

    2016-07-01

    The generation of wavefront phase dislocations of vortex Bessel light beams under acousto-optic (AO) diffraction in uniaxial crystals has been investigated. For the first time the process of AO interaction is studied with participation of Bessel acoustic beams instead of plane waves. A mathematical description of AO interaction is provided, which supposes the satisfaction of two types of phase-matching condition. The acousto-optic processes of transferring optical singularities onto the wavefront of BLBs are investigated and the generation of high-order optical vortices is considered at the interaction of optical and acoustical Bessel beams. The change of Bessel function order or phase dislocation order is explained as a result of the spin–orbital interaction under acousto-optic diffraction of vortex Bessel beams.

  5. High-Resolution Broadband Millimeter-Wave Astrophysical Spectrometer with Triple Product Acousto-Optical Processor

    NASA Astrophysics Data System (ADS)

    Dagostino, Miguel Chavez; Shcherbakov, Alexandre S.; Arellanes, Adan Omar; Chavushyan, Vahram

    An advanced conceptual design of a high-bit-rate triple product acousto-optical processor is presented that can be applied in a number of astrophysical problems. We briefly describe the Large Millimeter Telescope as one of the potential observational infrastructures where the acousto-optical spectrometer can be successfully used. A summary on the study of molecular gas in relatively old (age > 10 Myr) disks around main sequence stars is provided. We have identified this as one of the science cases in which the proposed processor can have a big impact. Then we put forward triple product acousto-optical processor is able to realize algorithm of the space-and-time integrating, which is desirable for a wide- band spectrum analysis of radio-wave signals with an improved resolution providing the resolution power of about 105 - 106. It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this al- gorithm is based on exploiting the chirp Z-transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of developing the triple product acousto-optical processor in frames of the astrophysical instrumentation is shortly discussed.

  6. Comparison of high repetition rate Q-switched 355nm ultraviolet lasers with EOM and AOM

    NASA Astrophysics Data System (ADS)

    Lu, Tingting; Li, Xiaolei; Zang, Huaguo; Zhu, Xiaolei

    2013-05-01

    Two kinds of Q-switched ultraviolet lasers using an acousto-optic modulator and an electro-optic modulator in the same cavity structure are demonstrated, with type I phase-matched LBO as second harmonic generation crystal and type II phase-matched LBO as third harmonic generation crystal. For acousto-optic Q-switched UV laser-a maximum average power of 6.3W with the shortest pulse width of 12 ns was obtained at the repetition rate of 22 kHz when the pump power reached 52.4 W. The optical conversion efficiency was up to 12%. Then we used a La3Ga5SiO14 crystal electro-optic modulator to replace the acousto-optic modulator. The 1.29W output power at 355nm wavelength was obtained at the repetition rate of 10 kHz when the pump power was increased to 20.4W, and the UV laser pulse width was as short as 9.6ns.The optical conversion efficiency was up to 6.3%.

  7. Depth discrimination in acousto-optic cerebral blood flow measurement simulation

    NASA Astrophysics Data System (ADS)

    Tsalach, A.; Schiffer, Z.; Ratner, E.; Breskin, I.; Zeitak, R.; Shechter, R.; Balberg, M.

    2016-03-01

    Monitoring cerebral blood flow (CBF) is crucial, as inadequate perfusion, even for relatively short periods of time, may lead to brain damage or even death. Thus, significant research efforts are directed at developing reliable monitoring tools that will enable continuous, bed side, simple and cost-effective monitoring of CBF. All existing non invasive bed side monitoring methods, which are mostly NIRS based, such as Laser Doppler or DCS, tend to underestimate CBF in adults, due to the indefinite effect of extra-cerebral tissues on the obtained signal. If those are to find place in day to day clinical practice, the contribution of extra-cerebral tissues must be eliminated and data from the depth (brain) should be extracted and discriminated. Recently, a novel technique, based on ultrasound modulation of light was developed for non-invasive, continuous CBF monitoring (termed ultrasound-tagged light (UTL or UT-NIRS)), and shown to correlate with readings of 133Xe SPECT and laser Doppler. We have assembled a comprehensive computerized simulation, modeling this acousto-optic technique in a highly scattering media. Using the combination of light and ultrasound, we show how depth information may be extracted, thus distinguishing between flow patterns taking place at different depths. Our algorithm, based on the analysis of light modulated by ultrasound, is presented and examined in a computerized simulation. Distinct depth discrimination ability is presented, suggesting that using such method one can effectively nullify the extra-cerebral tissues influence on the obtained signals, and specifically extract cerebral flow data.

  8. Highly efficient acousto-optic diffraction in Sn2P2S6 crystals.

    PubMed

    Martynyuk-Lototska, I Yu; Mys, O G; Grabar, A A; Stoika, I M; Vysochanskii, Yu M; Vlokh, R O

    2008-01-01

    We have studied the acousto-optic (AO) diffraction in Sn2P2S6 crystals and found that they manifest high values of an AO figure of merit. The above crystals may therefore be used as highly efficient materials in different AO applications. PMID:18157276

  9. Influence of Acoustic Field Structure on Polarization Characteristics of Acousto-optic Interaction in Crystals

    NASA Astrophysics Data System (ADS)

    Muromets, A. V.; Trushin, A. S.

    Influence of acoustic field structure on polarization characteristics of acousto-optic interaction is investigated. It is shown that inhomogeneity of acoustic field and mechanism of ultrasound excitation causes changes in values of acousto-optic figure of merit for ordinary and extraordinary light beams in comparison with theoretic values. The theoretic values were derived under assumption that acoustic wave is homogeneous. Experimental analysis was carried out in acousto-optic cell based on lithium niobate crystal where the acoustic wave propagates at the angle 13 degrees to Z axis of the crystal. We used three different methods of ultrasound generation in the crystal: by means of external piezotransducer, by interdigital transducer and by two sets of electrodes placed on top of the crystal surface. In the latter case, the first pair of the electrodes was directed along X crystal axis, while the second pair of the electrodes was directed orthogonally to X crystal axis and the direction of ultrasound. Obtained values for diffraction efficiencies for ordinary and extraordinary polarized optical beams were qualitatively different which may be caused by spatial inhomogeneity of the generated acoustic waves in the crystal. Structure of acoustic field generated by these sets of electrodes was examined by laser probing. We performed the analysis of the acoustic field intensity using acousto-optic method. A relation of diffraction efficiencies for ordinary and extraordinary light waves was measured during each iteration of the laser probing.

  10. Acousto-Optic Tunable Filter Hyperspectral Microscope Imaging Method for Characterizing Spectra from Foodborne Pathogens.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral microscope imaging (HMI) method, which provides both spatial and spectral characteristics of samples, can be effective for foodborne pathogen detection. The acousto-optic tunable filter (AOTF)-based HMI method can be used to characterize spectral properties of biofilms formed by Salmon...

  11. Acoustic waveguide technique for sensing incipient faults in underground power-transmission cables: including acousto-optic techniques. Final report

    SciTech Connect

    Harrold, R.T.

    1981-09-01

    The feasibility of using acoustic waveguide techniques for sensing incipient faults in underground power transmission cables was determined. Theoretical and practical studies were made of both the acoustic emission spectrum signatures associated with cable incipient faults, and the attenuation of acoustic waves in waterfilled metal tubes used as waveguides. Based on critical data, it can be estimated that in favorable circumstances, the acoustic waveguide system would only be useful for sensing incipient faults in underground cables of approx. 800 meters (approx. 0.5 miles) or less in length. As underground power transmission cables are often several kilometers in length, it was clear at this stage of the study, that simple acoustic waveguide sensing techniques would not be adequate, and some modification would be needed. With DOE approval it was decided to investigate acousto-optic sensing techniques in order to extend the detection range. In particular, a system in which acoustic emissions from cable incipient faults impinge on a fiber-optic lightguide and locally change its refractive indes, and as a consequence, modulate laser light transmitted along the light guide. Experiments based on this concept were successful, and it has been demonstrated that it is possible to sense acoustic emissions with energy levels below one micro-joule. A practical test of this system in the laboratory using a section of compressed gas-insulated cable with an internal flashover was successfully carried out. Long distance fault sensing with this technique should be feasible as laser light can be transmitted several kilometers in fiber optic lightguides. It is believed that laser-acousto-optic fault sensing is a viable technique which, with development, could be applied for fault sensing in power cables and other apparatus.

  12. Photorefractive acousto-optic imaging in thick scattering media at 790 nm with a Sn(2)P(2)S(6):Te crystal.

    PubMed

    Farahi, Salma; Montemezzani, Germano; Grabar, Alexander A; Huignard, Jean-Pierre; Ramaz, François

    2010-06-01

    Acousto-optic imaging is based on ultrasound modulation of multiply scattered light in thick media. We experimentally demonstrate the possibility to perform a self-adaptive wavefront holographic detection at 790nm, within the optical therapeutic window where absorption of biological tissues is minimized. A high-gain Te-doped Sn(2)P(2)S(6) crystal is used for this purpose. Optical absorbing objects embedded within a thick scattering phantom are imaged by use of pulsed ultrasound to get a dynamic millimetric axial resolution. Our technique represents an interesting approach for breast cancer detection. PMID:20517420

  13. Acousto-optic devices for operation with 2μm fibre lasers

    NASA Astrophysics Data System (ADS)

    Ward, J. D.; Stevens, G.; Shardlow, P. C.

    2016-03-01

    Fibre lasers operating in the 2μm region are of increasing interest for a range of applications, including laser machining and biomedical systems. The large mode area compared to 1μm fibre lasers combined with operation in an "eye-safe" region of the spectrum makes them particularly attractive. When developing fibre lasers at 1μm and 1·5μm manufacturers were able to call upon enabling technologies used by the telecoms industry, but at longer wavelengths, including 2μm, many such components are either unavailable or immature. We report on recent developments of Acousto-Optic Modulators and Tunable Filters that are specifically optimised for use with fibre systems operating at or around 2μm. AO devices are interesting due to their ability to conserve spatial-coherence, making them appropriate for use with single-mode optical fibres. We describe how the choice of interaction medium is an important consideration, particularly affecting the drive power and the polarisation behaviour of the device - the latter being an important parameter when used in a fibre system. We also describe two designs of AO Tunable Filter intended for laser tuning. Both designs have been demonstrated intracavity in 2μm fibre lasers. The first gives exceptionally narrow resolution (δλ/λ<0·1%). The second design is of a novel type of AOTF where a matched pair of AOTFs is configured to give a substantially net zero frequency-shift with little or no loss of pointing stability, any minor deviations in manufacture being self-compensated. Furthermore, small controlled frequency-shifts (up to about 10kHz) may be introduced with little or no detriment to the alignment of the system.

  14. Extending single molecule fluorescence observation time by amplitude-modulated excitation

    PubMed Central

    Kisley, Lydia; Chang, Wei-Shun; Cooper, David; Mansur, Andrea P; Landes, Christy F

    2014-01-01

    We present a hardware-based method that can improve single molecule fluorophore observation time by up to 1500% and super-localization by 47% for the experimental conditions used. The excitation was modulated using an acousto-optic modulator (AOM) synchronized to the data acquisition and inherent data conversion time of the detector. The observation time and precision in super-localization of four commonly used fluorophores were compared under modulated and traditional continuous excitation, including direct total internal reflectance excitation of Alexa 555 and Cy3, non-radiative Förster resonance energy transfer (FRET) excited Cy5, and direct epi-fluorescence wide field excitation of Rhodamine 6G. The proposed amplitude-modulated excitation does not perturb the chemical makeup of the system or sacrifice signal and is compatible with multiple types of fluorophores. Amplitude-modulated excitation has practical applications for any fluorescent study utilizing an instrumental setup with time-delayed detectors. PMID:24587894

  15. Piezo-optic, photoelastic, and acousto-optic properties of SrB4O7 crystals.

    PubMed

    Mytsyk, Bohdan; Demyanyshyn, Natalia; Martynyuk-Lototska, Irina; Vlokh, Rostyslav

    2011-07-20

    On the basis of studies of the piezo-optic effect, it has been shown that SrB(4)O(7) crystals can be used as efficient acousto-optic materials in the vacuum ultraviolet spectral range. The full matrices of piezo-optic and photoelastic coefficients have been experimentally obtained for these crystals. The acousto-optic figure of merit and the diffraction efficiency have been estimated for both the visible and deep ultraviolet spectral ranges. PMID:21772372

  16. Use of Multiband Acousto-optic Filters for Spectrally Encoded Signals Generation in Incoherent Optical Communication Systems

    NASA Astrophysics Data System (ADS)

    Byshevski-Konopko, O. A.; Proklov, V. V.; Filatov, A. L.; Lugovskoi, A. V.; Korablev, E. M.

    New acousto-optical (AO) coder of spectrally optical signals for optical code division multiple access systems (O-CDMA) was proposed and investigated. The coder was developed on a base of multi-frequency acousto-optical filter (MAOF). Control RF signals for MAOF were synthesized taking into account intermodulation distortions and interferences between different carrier frequencies incoming to MAOF. An industrial LED was used under system investigation.

  17. Independent acousto-optic separation of the two wavelengths of a polychromatic light beam

    NASA Astrophysics Data System (ADS)

    Kastelik, J. C.; Gazalet, Marc G.; Haine, F.; Pommeray, Michel

    1997-02-01

    A special configuration based on two successive acousto- optic interactions in uniaxial crystals with two noncollinear acoustic waves is presented. It leads to two angularly split wavelengths from a multiline laser beam with independent acousto-optic efficiencies. General expressions of the angular deviation and the spectral bandwidth are derived. Since the application concerns the restitution of colored images, a novel combination of wavelengths using the blue primary at 458 nm is investigated for trichromatic color matching. Numerical computations have been drawn for paratellurite. A practical separator using the slow shear wave in paratellurite is designed, and experimental results for the independent separation of 514- and 458-nm wavelengths of an Ar laser are reported.

  18. JPL activities on development of acousto-optic tunable filter imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Chao, Tien-Hsin; Reyes, George

    1992-01-01

    Recent activities of JPL in the development of a new type of imaging spectrometers for earth observation and planetary exploration are reported. This instrument uses the acousto-optic tunable filter (AOTF) as high resolution and fast programmable bandpass filter. AOTF operates in the principle of acousto-optic interaction in an anisotropic medium. This filter can be tuned in sequential, random, and multiwavelength access modes, providing observational flexibility. The diffraction process in the filter generates two diffracted monochromatic beams with polarization orthogonal to each other, creating a unique capability to measure both polarimetric and spectral properties of the incoming light simultaneously with a single instrument. The device gives wide wavelength operations with reasonably large throughput. In addition, it is in a compact solid-state structure without moving parts, providing system reliability. These attractive features give promising opportunities to develop a new generation of airborne/spaceborne and ground, real-time, imaging spectrometer systems for remote sensing applications.

  19. A recirculating delayed self-heterodyne method using a Mach-Zehnder modulator for kHz-linewidth measurement

    NASA Astrophysics Data System (ADS)

    Deng, Shuo; Li, Min; Gao, Hongyun; Dai, Yawen

    2016-09-01

    A laser linewidth measurement method which uses a Mach-Zehnder electro-optic modulator (MZM) is proposed in a loss-compensated recirculating delayed self-heterodyne interferometer (LC-RDSHI). Compared with the traditional acousto-optic modulator (AOM), the electro-optic modulator has the merits of broader bandwidth, lower insertion loss, higher extinction ratio and thus, a wider application. A theoretical analysis shows that the power spectrum curve of the novel measurement system is a Lorentzian line, which fits well with experiment. The linewidth is measured to be 137 ± 7 kHz at a frequency shift of 4 GHz. Measurement of a distributed feedback Bragg (DFB) laser has manifested that the linewidth broadens from 98.5 kHz to 137.4 kHz as the operating temperature changes by 16 °C. This work will allow investigation of narrow linewidth semiconductor and fiber laser stability.

  20. Acousto-optic interaction in alpha-BaB(2)O(4)and Li(2)B(4)O(7) crystals.

    PubMed

    Martynyuk-Lototska, Irina; Mys, Oksana; Dudok, Taras; Adamiv, Volodymyr; Smirnov, Yevgen; Vlokh, Rostyslav

    2008-07-01

    Experimental studies and analysis of acousto-optic diffraction in alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are given. Ultrasonic wave velocity, elastic compliance and stiffness coefficients, and piezo-optic and photoelastic coefficients of alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are determined. The acousto-optic figure of merit has been estimated for different possible geometries of acousto-optic interaction. It is shown that the acousto-optic figures of merit for alpha-BaB(2)O(4) crystals reach the value M(2)=(270 +/- 70) x 10(-15) s(3)/kg for the case of interaction with the slowest ultrasonic wave. The directions of propagation and polarization of those acoustic waves are obtained on the basis of construction of acoustic slowness surfaces. The acousto-optic diffraction is experimentally studied for alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals. PMID:18594591

  1. Some recollections on acousto-optics research at the University of Gdańsk in the light of international cooperation and of the history of Spring Schools on Acousto-Optics and Applications.

    PubMed

    Kwiek, Piotr; Sliwiński, Antoni

    2009-03-01

    Some historical features of international cooperation that have been a background for originating the idea to organize since 1980 special international meetings named Spring Schools on Acousto-Optics and Applications and for continuing the events until now are presented. Thanks to the establishment of the Spring Schools, the group of acousto-opticians at the Gdańsk University have had the opportunity to exchange scientific experience and continue mutual cooperation in research with several acousto-optic centers and to publish a number of common papers. A few examples from these achievements and some historical facts illustrating research activity in the field of acousto-optics during past 30 years are recollected. PMID:19252605

  2. Acousto-optic resonant coupling of three spatial modes in an optical fiber.

    PubMed

    Park, Hee Su; Song, Kwang Yong

    2014-01-27

    A fiber-optic analogue to an externally driven three-level quantum state is demonstrated by acousto-optic coupling of the spatial modes in a few-mode fiber. Under the condition analogous to electromagnetically induced transparency, a narrow-bandwidth transmission within an absorption band for the fundamental mode is demonstrated. The presented structure is an efficient converter between the fundamental mode and the higher-order modes that cannot be easily addressed by previous techniques, therefore can play a significant role in the next-generation space-division multiplexing communications as an arbitrarily mode-selectable router. PMID:24515208

  3. Study on spectrally agile staring sensor using acousto-optic tunable filter

    NASA Astrophysics Data System (ADS)

    Cui, Yan; Zhang, Minghui

    1992-08-01

    The spectrally agile staring sensor (SASS) is an instrument system that is able to get image and spectrum information. This paper analyzes the expression of signal-to-noise ratio and overall performance of the SASS system that uses an acousto-optic tunable filter as its spectral filter, and points out improving methods and limiting factors of the system performance. The complete SASS system experimental set-up is constructed. Using this set-up, the theory is verified, and the image and spectrum information of the simulated target is acquired.

  4. Acousto-optics bandwidth broadening in a Bragg cell based on arbitrary synthesized signal methods.

    PubMed

    Peled, Itay; Kaminsky, Ron; Kotler, Zvi

    2015-06-01

    In this work, we present the advantages of driving a multichannel acousto-optical deflector (AOD) with a digitally synthesized multifrequency RF signal. We demonstrate a significant bandwidth broadening of ∼40% by providing well-tuned phase control of the array transducers. Moreover, using a multifrequency, complex signal, we manage to suppress the harmonic deflections and return most of the spurious energy to the main beam. This method allows us to operate the AOD with more than an octave of bandwidth with negligible spurious energy going to the harmonic beams and a total bandwidth broadening of over 70%. PMID:26192666

  5. Wide-aperture acousto-optic tunable filters for visible and UV lights

    NASA Astrophysics Data System (ADS)

    Ponomarev, Andrei N.; Rodionov, Igor D.; Teterin, George E.

    1995-02-01

    Acousto optic filters (AOF) with optical size approximately 8 - 10 mm for visible and ultraviolet spectrum on the base of TeO2 and KH2 PO4 crystals correspondingly are developed and manufactured. The spectral resolution is better than 1 nm. The frequency bandwidth of both filters is 55 - 90 MHz, that allows us to use the only high frequency generator with two different power amplifiers. Acoustic power level for the AOFs on the base of TeO2 and KH2PO4 was about 1 W and 5 W, respectively. The optical tuning is carried out by means of a computer program.

  6. Electronically tunable coherent Raman spectroscopy using acousto-optics tunable filter.

    PubMed

    Petrov, Georgi I; Meng, Zhaokai; Yakovlev, Vladislav V

    2015-09-21

    Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, we demonstrated a novel instrumentation to the broadband coherent Raman spectroscopy. System's tunability allows assessing Raman transitions ranging from <400 cm(-1) to 4500 cm(-1). We validated the use of the new instrumentation by collecting coherent anti-Stokes spectra and stimulated Raman spectra of various samples. PMID:26406668

  7. Acoustic wave velocities in two-dimensional composite structures based on acousto-optical crystals

    NASA Astrophysics Data System (ADS)

    Mal'neva, P. V.; Trushin, A. S.

    2015-04-01

    Sound velocities in two-dimensional composite structures based on isotropic and anisotropic acousto-optical crystals have been determined by numerical simulations. The isotropic materials are represented by fused quartz (SiO2) and flint glass, while anisotropic materials include tetragonal crystals of paratellurite (TeO2) and rutile (TiO2) and a trigonal crystal of tellurium (Te). It is established that the acoustic anisotropy of periodic composite structures strongly depends on both the chemical composition and geometric parameters of components.

  8. Spin-to-orbit conversion at acousto-optic diffraction of light: conservation of optical angular momentum.

    PubMed

    Skab, Ihor; Vlokh, Rostyslav

    2012-04-01

    Acousto-optic diffraction of light in optically active cubic crystals is analyzed from the viewpoint of conservation of optical angular momentum. It is shown that the availability of angular momentum in the diffracted optical beam can be necessarily inferred from the requirements of angular momentum conservation law. As follows from our analysis, a circularly polarized diffracted wave should bear an orbital angular momentum. The efficiency of the spin-to-orbit momentum conversion is governed by the efficiency of acousto-optic diffraction. PMID:22505104

  9. Exploring Ramsey-coherent population trapping atomic clock realized with pulsed microwave modulated laser

    SciTech Connect

    Yang, Jing; Yun, Peter; Tian, Yuan; Tan, Bozhong; Gu, Sihong

    2014-03-07

    A scheme for a Ramsey-coherent population trapping (CPT) atomic clock that eliminates the acousto-optic modulator (AOM) is proposed and experimentally studied. Driven by a periodically microwave modulated current, the vertical-cavity surface-emitting laser emits a continuous beam that switches between monochromatic and multichromatic modes. Ramsey-CPT interference has been studied with this mode-switching beam. In eliminating the AOM, which is used to generate pulsed laser in conventional Ramsey-CPT atomic clock, the physics package of the proposed scheme is virtually the same as that of a conventional compact CPT atomic clock, although the resource budget for the electronics will slightly increase as a microwave switch should be added. By evaluating and comparing experimentally recorded signals from the two Ramsey-CPT schemes, the short-term frequency stability of the proposed scheme was found to be 46% better than the scheme with AOM. The experimental results suggest that the implementation of a compact Ramsey-CPT atomic clock promises better frequency stability.

  10. The Development and Field Testing of the Portable Acousto-optic Spectrometer for Astrobiology

    NASA Astrophysics Data System (ADS)

    Chanover, Nancy J.; Uckert, Kyle; Voelz, David; Boston, Penelope

    2014-11-01

    The development of in situ instrumentation for the detection of biomarkers on planetary surfaces is critical for the search for evidence of present or past life in our solar system. In our earlier instrument development efforts we addressed this need through the development of a near-infrared point spectrometer intended for quick-look examinations of samples that could be subsequently analyzed with a laser desorption time-of-flight mass spectrometer. The point spectrometer utilized an acousto-optic tunable filter (AOTF) crystal as the wavelength selecting element. In parallel with the aforementioned development efforts we identified the need for a portable version of the AOTF spectrometer that we could test and demonstrate in a range of field locations on Earth chosen to serve as terrestrial analogs for extreme environments elsewhere in the solar system. Here we describe the development and field testing of the Portable Acousto-optic Spectrometer for Astrobiology (PASA). We demonstrated this instrument in two very different cave environments, a predominantly gypsum and calcite cave in New Mexico and an actively forming cave rich in hydrated sulfates in Tabasco, Mexico. Both of these microbially active environments contain evidence of biologic alteration of minerals, which can be detected using IR spectroscopy. We will describe the instrument operations and present some data acquired with PASA to demonstrate its efficacy as a tool for biomarker detection on planetary surfaces. This work was supported by NASA's EPSCoR program through grant number NNX12AK77A.

  11. Spread function of acousto-optic filter with high-speed spectral image analysis

    NASA Astrophysics Data System (ADS)

    Zadorin, Anatoly S.; Nemtchenko, Andrei S.

    1998-08-01

    The contradictory requirements are presented to acousto- optic tunable filters (AOF) of spectral image analysis. On the one hand AOF should have high speed. On the other hand it should have good spectral resolution and wide angular aperture. Thus when AOF is fastly tuned with chirp transients, the diffracted wave intensity at different moments of transient process can considerably diverge form its quasistatic level. It means that spread function (SF) depends on the velocity of frequency tuning, i.e., it is described by 2D function with variables - wave length and velocity of frequency tuning. In Cartesian frame this dependence is presented by some surface being dynamic SF (DSF). It characterizes speed and selectivity properties of AOF. In this work DCF mathematical model was constructed and basic properties of spectral image analysis AOF were investigated. It has been established that the greatest distortions of DSF occur if velocity of frequency tuning has exceeded some critical value connected with acousto-optic interaction geometry and aperture sizes of beams. In this case the side lobes of SF will make 'false' maxima which begin to prevail over the basic. In addition under the conditions of phase mismatch DSF loses the symmetry to position of the main maximum. These effects reduce the accuracy of spectral measurements when tuning velocity is high.

  12. Acousto-optic Imaging System for In-situ Measurement of the High Temperature Distribution in Micron-size Specimens

    NASA Astrophysics Data System (ADS)

    Machikhin, Alexander S.; Zinin, Pavel V.; Shurygin, Alexander V.

    We developed a unique acousto-optic imaging system for in-situ measurement of high temperature distribution on micron-size specimens. The system was designed to measure temperature distribution inside minerals and functional material phases subjected to high pressure and high temperatures in a diamond anvil cell (DAC) heated by a high powered laser.

  13. Contrast enhancement in microscopy of human thyroid tumors by means of acousto-optic adaptive spatial filtering

    NASA Astrophysics Data System (ADS)

    Yushkov, Konstantin B.; Molchanov, Vladimir Y.; Belousov, Pavel V.; Abrosimov, Aleksander Y.

    2016-01-01

    We report a method for edge enhancement in the images of transparent samples using analog image processing in coherent light. The experimental technique is based on adaptive spatial filtering with an acousto-optic tunable filter in a telecentric optical system. We demonstrate processing of microscopic images of unstained and stained histological sections of human thyroid tumor with improved contrast.

  14. Electro-optic tuning and sidelobe control in acousto-optic tunable filters

    NASA Astrophysics Data System (ADS)

    Aronson, L. B.

    1995-01-01

    Both the center wavelength and the sidelobe structure of an integrated acousto-optic tunable filter (AOTF) are determined by the effective waveguide birefringence along the length of the device. By altering the birefringence by means of the electro-optic effect, one can control these device characteristics in potentially useful ways. Electro-optic tuning of the center frequency of an AOTF is demonstrated, and it is shown that this tuning mode, while limited to smaller ranges than acoustic frequency tuning, is many orders of magnitude faster. By use of multisection electrodes, dynamic control over the shape of the filter function is demonstrated. Finally, a number of practical uses of this technique are discussed.

  15. Use of acousto-optic tunable filter in fluorescence imaging endoscopy

    NASA Astrophysics Data System (ADS)

    Bouhifd, Mounir; Whelan, Maurice; Aprahamian, Marc

    2003-10-01

    A prototype instrument for fluorescence-based medical diagnostics in vivo is described. The system consists of a rigid endoscope comprising a UV laser-source for fluorescence excitation and a white light source for direct imaging. An acousto-optic tuneable filter (AOTF) is employed as a full-field tuneable bandpass filter. This allows fast continuous or random-access tuning with high filtering efficiency. A study of the diagnostic potential of fluorescence imaging for pancreatitis was conducted on a rat model. In particular, the aim was to detect autofluorescence of endogenous protoporphyrin IX (PpIX) that has been shown to accumulate in early-stage diseased tissue undergoing an inflammatory response.

  16. Tapered acoustical directional couplers for integrated acousto-optical mode converters with weighted coupling

    NASA Astrophysics Data System (ADS)

    Herrmann, Harald; Rust, Ulrich; Schafer, Klaus

    1995-03-01

    Weighted coupling for strong sidelobe suppression of integrated acoustooptical mode converters in LiNbO3 using acoustical directional couplers has been studied theoretically and experimentally. A parameter free model for the propagation of surface acoustic waves in guiding structures has been developed based on a step-like variation of the acoustic velocity. Comparisons of theoretical results with experimental ones for acoustic waveguides and directional coupler structures confirm the applicability of the model. A coupled mode description of the acousto-optical polarization conversion in converters with acoustical directional couplers has been developed and applied to several tapered acoustical directional couplers. The model reveals that the conversion characteristics are usually strongly asymmetric. If the directional coupler is appropriately designed, a sidelobe suppression of about 30 dB can be achieved. First experimental results with tapered directional couplers confirm within some limits the theoretical predictions.

  17. Acousto-optic method used to control water pollution by miscible liquids

    NASA Astrophysics Data System (ADS)

    Ferria, Kouider; Griani, Lazhar; Laouar, Naamane

    2012-05-01

    An acousto-optic (A.O.) method has been developed for controlling the quality of water mixed by miscible liquids like acetone or ethanol… The liquid mixture is filled in a rectangular glass cell, which is placed orthogonally to the incident collimated beam of light. This cell consists of a piezoelectric transducer for generating ultrasonic waves. The collimated light while passing through this cell undergoes a diffraction phenomenon. The diffracted dots are collected by a converging photographic objective and displayed in its back focal plane. The location of the diffracted dots and their intensity are sensitive to any variation of the interaction medium. This result leads to decide about the quality of the water.

  18. Effect of metal coating in all-fiber acousto-optic tunable filter using torsional wave.

    PubMed

    Song, Du-Ri; Jun, Chang Su; Do Lim, Sun; Kim, Byoung Yoon

    2014-12-15

    Torsional mode acousto-optic tunable filter (AOTF) is demonstrated using a metal-coated birefringent optical fiber for an improved robustness. The changes in acoustic and optical properties of a metal-coated birefringent optical fiber induced by the thin metal coating were analyzed experimentally and theoretically. The filter wavelength shift is successfully explained as a result of combined effect of acoustic wavelength change and optical birefringence change. We also demonstrated a small form-factor configuration by coiling the fiber with 6 cm diameter without performance degradation. The center wavelength of the filter can be tuned >35 nm by changing the applied frequency, and the coupling efficiency is higher than 92% with <5 nm 3-dB bandwidth. PMID:25607036

  19. Dynamic 3D imaging based on acousto-optic heterodyne fringe interferometry.

    PubMed

    Guan, Yingjian; Yin, Yongkai; Li, Ameng; Liu, Xiaoli; Peng, Xiang

    2014-06-15

    An acoustic-optics heterodyne fringe interferometry coupled with a three-camera system is developed for dynamic 3D imaging. In this system, first-order beams with a slight frequency difference diffracted from two acousto-optic deflectors (AODs) form a beat intensity fringe pattern. Setting the frequency of the trigger signal for the CCD cameras into four times the beat frequency, four-step phase-shifting fringe patterns can be obtained, and the wrapped phase map (WPM) can be calculated. Under the epipolar constraint among three cameras, the homologous points can be determined unambiguously with the assistant of a WPM; thus the 3D shape can be reconstructed while skipping the phase unwrapping step. Experimental results are presented to validate this approach. PMID:24978566

  20. Dynamic acousto-optic control of a strongly coupled photonic molecule

    PubMed Central

    Kapfinger, Stephan; Reichert, Thorsten; Lichtmannecker, Stefan; Müller, Kai; Finley, Jonathan J.; Wixforth, Achim; Kaniber, Michael; Krenner, Hubert J.

    2015-01-01

    Strongly confined photonic modes can couple to quantum emitters and mechanical excitations. To harness the full potential in quantum photonic circuits, interactions between different constituents have to be precisely and dynamically controlled. Here, a prototypical coupled element, a photonic molecule defined in a photonic crystal membrane, is controlled by a radio frequency surface acoustic wave. The sound wave is tailored to deliberately switch on and off the bond of the photonic molecule on sub-nanosecond timescales. In time-resolved experiments, the acousto-optically controllable coupling is directly observed as clear anticrossings between the two nanophotonic modes. The coupling strength is determined directly from the experimental data. Both the time dependence of the tuning and the inter-cavity coupling strength are found to be in excellent agreement with numerical calculations. The demonstrated mechanical technique can be directly applied for dynamic quantum gate operations in state-of-the-art-coupled nanophotonic, quantum cavity electrodynamic and optomechanical systems. PMID:26436203

  1. Acousto-optic interaction in biconical tapered fibers: shaping of the stopbands

    NASA Astrophysics Data System (ADS)

    Ramírez-Meléndez, Gustavo; Bello-Jiménez, Miguel Ángel; Cuadrado-Laborde, Christian; Díez, Antonio; Cruz, José Luis; Rodríguez-Cobos, Amparo; Balderas-Navarro, Raúl; Andrés Bou, Miguel Vicente

    2016-03-01

    The effect of a gradual reduction of the fiber diameter on the acousto-optic (AO) interaction is reported. The experimental and theoretical study of the intermodal coupling induced by a flexural acoustic wave in a biconical tapered fiber shows that it is possible to shape the transmission spectrum, for example, substantially broadening the bandwidth of the resonant couplings. The geometry of the taper transitions can be regarded as an extra degree of freedom to design the AO devices. Optical bandwidths above 45 nm are reported in a tapered fiber with a gradual reduction of the fiber down to 70 μm diameter. The effect of including long taper transition is also reported in a double-tapered structure. A flat attenuation response is reported with 3-dB stopband bandwidth of 34 nm.

  2. [Preliminary study on using acousto-optic tunable filter as wavelength selector for atomic absorption spectrometry].

    PubMed

    Zhao, Li-wei; Zhang, Yi-hua; Wang, Mei-jia; Song, Da-qian; Zhang, Han-qi; Jin, Qin-han

    2002-06-01

    An acousto-optic tunable filter (AOTF) is an all-solid-state, electronic monochromator that is based on the diffraction of light by an acoustic wave in an anisotropic crystal. It is a new kind of tunable small filter with narrow band compared with traditional unicolor filter. The filter can diffract incident white light at a specific wavelength when a specific radio frequency is applied into it. An AAS experimental setup using a microwave plasma torch (MPT) as the atomizer, and a visible AOTF as the wavelength selector was developed and the analytical performance was evaluated by determination of Na. The effect on the absorption signal of some operating conditions, including the observation height, the microwave forward power and the carrier and support gas flow rates for MPT, were investigated. The detection limit for Na was shown to be 0.23 microgram.mL-1 and the relative standard deviation was 2.6% (n = 6). PMID:12938338

  3. Time and space integrating acousto-optic folded spectrum processing for SETI

    NASA Technical Reports Server (NTRS)

    Wagner, K.; Psaltis, D.

    1986-01-01

    Time and space integrating folded spectrum techniques utilizing acousto-optic devices (AOD) as 1-D input transducers are investigated for a potential application as wideband, high resolution, large processing gain spectrum analyzers in the search for extra-terrestrial intelligence (SETI) program. The space integrating Fourier transform performed by a lens channels the coarse spectral components diffracted from an AOD onto an array of time integrating narrowband fine resolution spectrum analyzers. The pulsing action of a laser diode samples the interferometrically detected output, aliasing the fine resolution components to baseband, as required for the subsequent charge coupled devices (CCD) processing. The raster scan mechanism incorporated into the readout of the CCD detector array is used to unfold the 2-D transform, reproducing the desired high resolution Fourier transform of the input signal.

  4. Compensation of spatial dispersion of an acousto-optic deflector with a special Keplerian telescope.

    PubMed

    Hu, Qinglei; Zhou, Zhenqiao; Lv, Xiaohua; Zeng, Shaoqun

    2016-01-15

    Compensation of spatial dispersion caused by the acousto-optic deflector (AOD) when using a femtosecond laser is difficult across the whole scanning range of the system, and this is a significant impediment to its use. In conventional methods, the dispersion of the AOD was compensated only when it was at a particular position, while at other positions, the quality of the light beam was reduced. We developed a novel method for compensating the spatial dispersion within the entire scanning range using a special Keplerian telescope. Our experimental results show that the residual dispersion of the AOD is compensated sufficiently, and the focal spots of the laser reach the diffraction limit within a 40-MHz ultrasound bandwidth. PMID:26766675

  5. Exact solution for four-order acousto-optic Bragg diffraction with arbitrary initial conditions.

    PubMed

    Pieper, Ron; Koslover, Deborah; Poon, Ting-Chung

    2009-03-01

    An exact solution to the four-order acousto-optic (AO) Bragg diffraction problem with arbitrary initial conditions compatible with exact Bragg angle incident light is developed. The solution, obtained by solving a 4th-order differential equation, is formalized into a transition matrix operator predicting diffracted light orders at the exit of the AO cell in terms of the same diffracted light orders at the entrance. It is shown that the transition matrix is unitary and that this unitary matrix condition is sufficient to guarantee energy conservation. A comparison of analytical solutions with numerical predictions validates the formalism. Although not directly related to the approach used to obtain the solution, it was discovered that all four generated eigenvalues from the four-order AO differential matrix operator are expressed simply in terms of Euclid's Divine Proportion. PMID:19252607

  6. Tunable broadband light coupler based on two parallel all-fiber acousto-optic tunable filters.

    PubMed

    Zhang, Wending; Huang, Ligang; Gao, Feng; Bo, Fang; Zhang, Guoquan; Xu, Jingjun

    2013-07-15

    Based on the evanescent-field coupling between the cladding modes of two adjacent and parallel all-fiber acousto-optic tunable filters, tunable broadband light coupling with relatively uniform insertion loss of trapping spectrum was achieved. In the experiments, a wide spectral tuning range from 1490 nm to 1610 nm, covering the whole C- and L-band and parts of S-bands, was demonstrated with a wavelength tunability slope of -0.72 nm/kHz. The insertion loss of the trapping spectrum was uniform (around -5.0 dB, which can be improved with a longer evanescent-field coupling length) within the whole tuning spectral range. Such a light coupling structure would be useful in tunable broadband light coupler and broadband optical fiber add/drop multiplexer for applications in coarse wavelength division multiplexing systems. PMID:23938513

  7. AOM/DSS Model of Colitis-Associated Cancer.

    PubMed

    Parang, Bobak; Barrett, Caitlyn W; Williams, Christopher S

    2016-01-01

    Our understanding of colitis-associated carcinoma (CAC) has benefited substantially from mouse models that faithfully recapitulate human CAC. Chemical models, in particular, have enabled fast and efficient analysis of genetic and environmental modulators of CAC without the added requirement of time-intensive genetic crossings. Here we describe the Azoxymethane (AOM)/Dextran Sodium Sulfate (DSS) mouse model of inflammatory colorectal cancer. PMID:27246042

  8. An acousto-optical method for registration of erythrocytes' agglutination reaction—sera color influence on the resolving power

    NASA Astrophysics Data System (ADS)

    Doubrovski, V. A.; Medvedeva, M. F.; Torbin, S. O.

    2016-01-01

    The absorption spectra of agglutinating sera were used to determine blood groups. It was shown experimentally that the sera color significantly affects the resolving power of the acousto-optical method of blood typing. In order to increase the resolving power of the method and produce an invariance of the method for sera color, we suggested introducing a probing light beam individually for different sera. The proposed technique not only improves the resolving power of the method, but also reduces the risk of false interpretation of the experimental results and, hence, error in determining the blood group of the sample. The latter is especially important for the typing of blood samples with weak agglutination of erythrocytes. This study can be used in the development of an instrument for instrumental human blood group typing based on the acousto-optical method.

  9. Analytical study of acousto/optical holography-interfacing methods for acoustical and optical holography NDT research

    NASA Technical Reports Server (NTRS)

    El-Sum, H. M. A.

    1976-01-01

    The international status of the art of acousto optical imaging techniques adaptable to nondestructive testing and, interfacing methods for acoustical and optical holography in nondestructive testing research are studied. Evaluation of 20 different techniques encompassed investigation of varieties of detectors and detection schemes, all of which are described and summarized. Related investigation is reported in an Appendix. Important remarks on image quality, factors to be considered in designing a particular system, and conclusions and recommendations are presented. Three bibliographies are included.

  10. Simultaneous multiple-depths en-face optical coherence tomography using multiple signal excitation of acousto-optic deflectors.

    PubMed

    Zurauskas, Mantas; Rogers, John; Podoleanu, Adrian Gh

    2013-01-28

    We present a novel low-coherence interferometer configuration, equipped with acousto-optic deflectors that can be used to simultaneously acquire up to eight time domain optical coherence tomography en-face images. The capabilities of the configuration are evaluated in terms of depth resolution, signal to noise ratio and crosstalk. Then the configuration is employed to demonstrate simultaneous en-face optical coherence tomography imaging at five different depths in a specimen of armadillidium vulgare. PMID:23389175

  11. Generation of spectral-encoded signals in noncoherent optical communication systems based on acousto-optic multiwavelength filters

    NASA Astrophysics Data System (ADS)

    Proklov, V. V.; Byshevski-Konopko, O. A.; Filatov, A. L.

    2015-10-01

    New acousto-optical (AO) methods and devices necessary for the creation of noncoherent optical code division multiple access (O-CDMA) systems are considered. Based on an AO multiwavelength filter, an original device generating spectral-encoded signals for O-CDMA systems with optimum WDM has been created and studied. It is shown that modern AO technology is capable of surmounting difficulties that previously hindered the transition of optical communication systems to CDMA data transmission.

  12. Acousto-Optic Tunable Filter Spectroscopic Instrumentation for Quantitative Near-Ir Analysis of Organic Materials.

    NASA Astrophysics Data System (ADS)

    Eilert, Arnold James

    1995-01-01

    The utility of near-IR spectroscopy for routine quantitative analyses of a wide variety of compositional, chemical, or physical parameters of organic materials is well understood. It can be used for relatively fast and inexpensive non-destructive bulk material analysis before, during, and after processing. It has been demonstrated as being a particularly useful technique for numerous analytical applications in cereal (food and feed) science and industry. Further fulfillment of the potential of near-IR spectroscopic analysis, both in the process and laboratory environment, is reliant upon the development of instrumentation that is capable of meeting the challenges of increasingly difficult applications. One approach to the development of near-IR spectroscopic instrumentation that holds a great deal of promise is acousto-optic tunable filter (AOTF) technology. A combination of attributes offered by AOTF spectrometry, including speed, optical throughput, wavelength reproducibility, ruggedness (no -moving-parts operation) and flexibility, make it particularly desirable for numerous applications. A series of prototype (research model) acousto -optic tunable filter instruments were developed and tested in order to investigate the feasibility of the technology for quantitative near-IR spectrometry. Development included design, component procurement, assembly and/or configuration of the optical and electronic subsystems of which each functional spectrometer arrangement was comprised, as well as computer interfacing and acquisition/control software development. Investigation of this technology involved an evolution of several operational spectrometer systems, each of which offered improvements over its predecessor. Appropriate testing was conducted at various stages of development. Demonstrations of the potential applicability of our AOTF spectrometer to quantitative process monitoring or laboratory analysis of numerous organic substances, including food materials, were

  13. Calomel-made crystalline acousto-optical cell designed for an advanced regime of noncollinear two-phonon light scattering

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Alexandre S.; Arellanes, Adan Omar

    2016-03-01

    We study the potentials of a wide-aperture crystalline calomel-made acousto-optical cell. Characterizing this cell is nontrivial due to the chosen regime based on an advanced noncollinear two-phonon light scattering. Recently revealed important features of this phenomenon are essentially exploited in the cell and are investigated in more detail. These features can be observed more easily and simply in tetragonal crystals, e.g., calomel, exhibiting specific acousto-optical nonlinearity caused by the acoustic waves of finite amplitude. This parametric nonlinearity manifests itself at low acoustic powers in calomel possessing linear acoustic attenuation. The formerly identified additional degree of freedom, unique to this regime, is exploited for designing the cell with an eye to doubling the resolution due to two-phonon processes. We clarify the role of varying the central acoustic frequency and acoustic attenuation using that degree of freedom. Then the efficiency of calomel is exploited to expand the cell's bandwidth with a cost of its efficiency. Proof-of-principle experiments confirm the developed approaches and illustrate their applicability to innovative techniques of optical spectrum analysis with the improved resolution. The achieved spectral resolution of 0.205 Å at 405 nm and the resolving power 19,800 are the best for acousto-optical spectrometers dedicated to space or airborne operations to date as far as we know.

  14. Optimization of spectral filtering parameters of acousto-optic pure rotational Raman lidar for atmospheric temperature profiling

    NASA Astrophysics Data System (ADS)

    Zhu, Jianhua; Wan, Lei; Nie, Guosheng; Guo, Xiaowei

    2003-12-01

    In this paper, as far as we know, it is the first time that a novel acousto-optic pure rotational Raman lidar based on acousto-optic tunable filter (AOTF) is put forward for the application of atmospheric temperature measurements. AOTF is employed in the novel lidar system as narrow band-pass filter and high-speed single-channel wavelength scanner. This new acousto-optic filtering technique can solve the problems of conventional pure rotational Raman lidar, e.g., low temperature detection sensitivity, untunability of filtering parameters, and signal interference between different detection channels. This paper will focus on the PRRS physical model calculation and simulation optimization of system parameters such as the central wavelengths and the bandwidths of filtering operation, and the required sensitivity. The theoretical calculations and optimization of AOTF spectral filtering parameters are conducted to achieve high temperature dependence and sensitivity, high signal intensities, high temperature of filtered spectral passbands, and adequate blocking of elastic Mie and Rayleigh scattering signals. The simulation results can provide suitable proposal and theroetical evaluation before the integration of a practical Raman lidar system.

  15. An acousto-optic tunable filter enhanced CO{sub 2} lidar atmospheric monitor

    SciTech Connect

    Taylor, L.H.; Suhre, D.R.; Mani, S.S.

    1996-12-31

    The atmospheric monitor conceptual design is based on a pulsed CO{sub 2} laser. The narrow laser lines provide high spectral selectivity in the 9-11 {mu}m region, within the 8-14 {mu}m ``fingerprint`` region where most large molecules have unique spectral absorption signatures. Laser power has been chosen so that topological objects, e.g., trees or buildings, as far as 4 km can be used as backreflectors, but the laser intensity is sufficiently low that the laser beam is eye-safe. Time-of-flight measurements give the distance to the topological reflector. The lidar system is augmented with an acousto-optic tunable filter (AOTF) which measures the thermal emission spectra from 3 to 14 {mu}m with a 3 cm{sup -1} passband. Sensitivity to narrow emission lines is enhanced by derivative spectroscopy in which the passband of the AOTF is dithered via the rf drive. Path-averaged concentrations are determined from the emission intensity and laser- determined range.

  16. Advanced fluorescence imaging endoscopy using an acousto-optic tuneable filter

    NASA Astrophysics Data System (ADS)

    Whelan, Maurice P.; Bouhifd, Mounir; Aprahamian, Marc

    2004-07-01

    Two novel prototype instruments for in vivo fluorescence-based medical diagnostics are described. The devices are based on an acousto-optic tuneable filter (AOTF) and can be easily attached to the eyepiece of most commercially available endoscopes. The instruments developed offer significant advantages over typical fixed-filter or filter-wheel fluorescence imaging systems in terms of flexibility, performance and diagnostic potential. Any filtering center-wavelength in the range from 450 to 700 nm can be rapidly selected either by random access or sequential tuning using simple commands delivered over a PC serial interface. In addition, both filtered and unfiltered light can be imaged to facilitate the direct association of fluorescence signals with specific anatomical sites. To demonstrate the system in vivo, a study of the diagnostic potential of fluorescence imaging for pancreatitis was conducted on rats. The aim was to detect extremely low-levels of endogenous protoporphyrin IX (PpIX) that has been shown to accumulate in early-stage diseased tissue undergoing an inflammatory response. Results show clearly that the device is effective in diagnosing mild pancreatitis in rats without the necessity of administering PpIX promoting agents such as ALA. Planning of human clinical trials is currently underway to demonstrate its potential as a tool for non-invasive early diagnosis of gastroenterological diseases.

  17. SWAS-AOS: the first acousto-optical spectrometer in space

    NASA Astrophysics Data System (ADS)

    Frerick, Johannes; Klumb, Markus; Schieder, Rudolf; Tolls, Volker; Winnewisser, Gisbert F.

    1999-12-01

    On December 5, 1998, the Submillimeter Wave Astronomy Satellite has been launched with a PEGASUS carrier after more than 3 years delay. SWAS is observing molecular line signals (H2O, 13CO, Cl, O2 and H2 18O) from astronomical sources at frequencies between 487 and 557 GHz. SWAS is the first sub-millimeter heterodyne space mission, and, for the spectral analysis of the received signals, it carries the first acousto-optical spectrometer (AOS) in space. The AOS has been built at University of Cologne, and it covers 1.4 GHz bandwidth with approximately 1400 frequency channels. The total weight is 7.5 kg and the power consumption is 5.5 Watts only. The very stable temperature conditions on SWAS allow longtime integrations at total observing times far above 100 hours still with radiometric performance. So far, the AOS- spectra have not been degraded by particle hits, particularly the CCD detector of the AOS does not exhibit any visible effect due to cosmic rays. SWAS has already observed many interstellar sources in our galaxy. Emission of water is seen to be very abundant, while signals of molecular oxygen seem to be too weak to be observable.

  18. Investigation of acousto-optic properties of tellurium-based glasses for infrared applications

    NASA Astrophysics Data System (ADS)

    Voloshinov, V. B.; Gupta, N.; Kulakova, L. A.; Khorkin, V. S.; Melekh, B. T.; Knyazev, G. A.

    2016-02-01

    We examined the physical properties of infrared optical glasses composed of tellurium, germanium, selenium, sulfur and silicon. In particular, we measured optical, acoustic and photoelastic parameters of the following alloy compounds: germanium-selenium-tellurium (Ge-Se-Te), germanium-selenium-sulfur-tellurium (Ge-Se-S-Te), germanium-silicon-tellurium (Ge-Si-Te) and silicon-tellurium (Si-Te). Like single-crystal tellurium, the glasses demonstrate good acousto-optic (AO) diffraction efficiency and have reasonable optical transparency in a wide spectral region covering wavelengths from 1.5 to 20 μm. The optical, acoustic and photoelastic properties of the tellurium-based compounds were measured using infrared lamp sources of radiation as well as He-Ne and CO2 lasers. In this paper, we report on the optical, acoustic and photoelastic parameters of a selection of these compounds and discuss the advantages and disadvantages of using these glasses for AO device applications. We also present the measured characteristics of an AO cell fabricated in a Si20Te80 glass material which exhibited high optical uniformity and long-term chemical stability.

  19. A Lyman-alpha tunable acousto-optic filter for detecting superthermal flare protons

    NASA Technical Reports Server (NTRS)

    Mickey, Donald L.

    1994-01-01

    The goal of this project was to develop and characterize a narrow-band, tunable filter for use near the Lyman-alpha line of hydrogen at 121.6 nm. Such a filter could form the critical component of an instrument to observe asymmetries in the solar Lyman-alpha line, caused by energetic protons accelerated during the impulsive phase of solar flares. Characteristic charge-exchange nonthermal emission at Lyman alpha should be produced when sub-MeV protons are injected into the chromosphere, but no instrument suitable for their detection has been developed. Such an instrument would require a narrow-band (less than 0.01 nm) tunable filter with aperture and throughput consistent with imaging a solar active region at 0.1 second intervals. The development of acousto-optic tunable filters (AOTF) suitable for use as compact, simple tunable filters for astronomical work suggested an investigation into the use of an AOTF at Lyman-alpha.

  20. The Aerosol Limb Imager: acousto-optic imaging of limb scattered sunlight for stratospheric aerosol profiling

    NASA Astrophysics Data System (ADS)

    Elash, B. J.; Bourassa, A. E.; Loewen, P. R.; Lloyd, N. D.; Degenstein, D. A.

    2015-12-01

    The Aerosol Limb Imager (ALI) is an optical remote sensing instrument designed to image scattered sunlight from the atmospheric limb. These measurements are used to retrieve spatially resolved information of the stratospheric aerosol distribution, including spectral extinction coefficient and particle size. Here we present the design, development and test results of an ALI prototype instrument. The long term goal of this work is the eventual realization of ALI on a satellite platform in low earth orbit, where it can provide high spatial resolution observations, both in the vertical and cross-track. The instrument design uses a large aperture Acousto-Optic Tunable Filter (AOTF) to image the sunlit stratospheric limb in a selectable narrow wavelength band ranging from the visible to the near infrared. The ALI prototype was tested on a stratospheric balloon flight from the Canadian Space Agency (CSA) launch facility in Timmins, Canada, in September 2014. Preliminary analysis of the hyperspectral images indicate that the radiance measurements are of high quality, and we have used these to retrieve vertical profiles of stratospheric aerosol extinction coefficient from 650-1000 nm, along with one moment of the particle size distribution. Those preliminary results are promising and development of a satellite prototype of ALI within the Canadian Space Agency is ongoing.

  1. Double-filtering method based on two acousto-optic tunable filters for hyperspectral imaging application.

    PubMed

    Wang, Pengchong; Zhang, Zhonghua

    2016-05-01

    A hyperspectral imaging system was demonstrated based on two acousto-optic tunable filters (AOTFs). Efficient regulation of the incoherent beam was executed by means of the wide-angular regime of Bragg diffraction in the birefringent materials. A double-filtering process was achieved when these two AOTFs operated with a central wavelength difference. In comparison with the single-filtering method, the spectral bandwidth was greatly compressed, giving an increment of 42.02% in spectral resolution at the wavelength of 651.62 nm. Experimental results and theoretical calculations are basically identical. Furthermore, the sidelobe was found to be suppressed by the double-filtering process with the first order maximum decreased from -9.25 dB to -22.35 dB. The results indicated high spectral resolution and high spectral purity were obtained simultaneously from this method. The basic spectral resolution performance was examined with a didymium glass by this configuration. We present our experimental methods and the detailed results obtained. PMID:27137600

  2. Radiometric calibration and noise estimation of acousto-optic tunable filter hyperspectral imaging systems.

    PubMed

    Katrašnik, Jaka; Pernuš, Franjo; Likar, Boštjan

    2013-05-20

    The accuracy of the radiometric response of acousto-optic tunable filter (AOTF) hyperspectral imaging systems is crucial for obtaining reliable measurements. It is therefore important to know the radiometric response and noise characteristics of the hyperspectral imaging system used. A radiometric model of an AOTF hyperspectral imaging system composed of an imaging sensor radiometric model (CCD, CMOS, and sCMOS) and an AOTF light transmission model is proposed. Using the radiometric model, a method for obtaining the fixed pattern noise (FPN) of the imaging system by displacing and imaging an illuminated reference target is developed. Methods for estimating the temporal noise of the imaging system, using the photon transfer method, and for correcting FPN are also presented. Noise estimation and image restoration methods were tested on an AOTF hyperspectral imaging system. The results indicate that the developed methods can accurately calculate temporal and FPN, and can effectively correct the acquired images. After correction, the signal-to-noise ratio of the acquired images was shown to increase by 26%. PMID:23736239

  3. Performance of a laser communication system with acousto-optic tracking: an experimental study

    NASA Astrophysics Data System (ADS)

    Nikulin, V.; Khandekar, R.; Sofka, J.

    2006-02-01

    Laser communication systems hold great promise for broadband applications. This technology uses much higher-than-RF region of the spectrum and allows concentration of the signal within a very small spatial angle, thus offering unsurpassed throughput, information security, reduced weight and size of the components and power savings. Unfortunately, these intrinsic advantages do not come without a price: small beam divergence requires precise positioning, which becomes very critical at high bit rates. Complex motion patterns of the communicating platforms, resident vibrations, and atmospheric effects are known to cause significant signal losses through the mechanisms of the pointing errors, beam wander and other higher-order effects. Mitigation of those effects is achieved through the multiple means of fast tracking and wavefront control. In this paper we focus on the application of a beam steering technology and its effect on the communication performance of the system. We present the results of an experimental study of a laser communication link subjected to pointing distortions. These distortions are generated by a special disturbance element in the optical setup, which recreates specific operation environments with particular spectral characteristics. The acousto-optic technology is used to build an agile tracking system to assure the maximum signal reception in spite of the harsh operational conditions. The received communication signal is recorded and statistically analyzed to calculate the bit-error-rates. This paper presents the synthesis of a tracking system and the experimental results characterizing the communication performance under uncompensated pointing disturbance and with tracking.

  4. Director-density coupling theory of the acousto-optic effect in nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Sátiro, Caio; Vitoriano, Carlindo

    2011-10-01

    Experiments with nematic liquid crystals have proved that an ultrasonic wave exerts a torque on the liquid-crystal molecules, causing a change in its optical properties (acousto-optic effect). In this work we report a theoretical study on the theory proposed by Selinger [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.66.051708 66, 051708 (2002).] and, independently, by Boneto [Chem. Phys. Lett.CHPLBC0009-261410.1016/S0009-2614(02)00906-5 361, 237 (2002).] for this effect. We solved exactly the Euler-Lagrange equation, which determines the equilibrium configuration of the director profile. The liquid-crystal director is also calculated in powers of the acoustic intensity and a comparison of this expansion with the solution in a closed form is given. We show the existence of minimizers that does not satisfy the Euler-Lagrange equation and report the possibility of observing a Fréedericksz-type transition. Finally, a possibility of controlling light by ultrasonic wave is also discussed in the limit of low acoustic intensity.

  5. Configurable-bandwidth imaging spectrometer based on an acousto-optic tunable filter

    NASA Astrophysics Data System (ADS)

    Vila-Francés, Joan; Calpe-Maravilla, Javier; Muñoz-Mari, Jordi; Gómez-Chova, Luis; Amorós-López, Julia; Ribes-Gómez, Emilio; Durán-Bosch, Vicente

    2006-07-01

    This article presents a new imaging spectrometer called autonomous tunable filtering system. The instrument acquires sequential images at different spectral wavelengths in the visible and near infrared range of the electromagnetic spectrum. The spectral selection is performed by an acousto-optic tunable filter (AOTF), which is driven by a custom radio-frequency (rf) generator based on a direct digital synthesizer (DDS). The DDS allows a high flexibility in terms of acquisition speed and bandwidth selection. The rf power is dynamically controlled to drive the AOTF with the optimum value for each wavelength. The images are formed through a carefully designed optical layout and acquired with a high performance digital camera. The application software controls the instrument and acquires the raw spectral images from the camera. This software optionally corrects the image for the AOTF nonidealities, such as diffraction efficiency variations, spatial nonuniformity, and chromatic aberration, and generates a single multiband image file. Moreover, the software can calculate the reflectance or transmittance of the acquired images. The instrument has been calibrated to give precise and repetitive measurements and has been validated against a high performance point spectrometer. As a case example, the instrument has been successfully used for the mapping of chlorophyll content of plant leaves from their multispectral reflectance images.

  6. Instrumentation of a compact random-access photostimulator based on acousto-optic deflectors

    NASA Astrophysics Data System (ADS)

    Liu, Yafeng; Zhao, Yuan; Lv, Xiaohua; Li, Yiding; Zhang, Xiaohui; Zhang, Jie; Wang, Liping; Zeng, Shaoqun

    2012-02-01

    Recently developed optogenetics provides a fast, non-invasive, and efficient method for cell activation. However, it is difficult for the optical stimulators used for optogenetics to realize selective multi-site fast activation. In this paper, we developed a random-access photostimulator based on a pair of perpendicularly oriented acousto-optic deflectors. Precise laser targeting in the x-y plane was verified, and the lateral spatial resolution of laser intensity after the objective was measured as ˜1.38 μm. Photostimulaton of ChETA-expressing astrocytes induced reliable inward currents only if the laser beam was directed onto the targeted cell. In the ChR2-expresing neuron, multiple locations along two dendrites were stimulated, and spatiotemporal integration was observed in the soma with fast multi-site activation. These results demonstrated that this random-access photostimulator would be a powerful tool for selective multi-site fast activation. The compact and modular design of this photostimulator makes it easily integrated with different commercial microscopes, and thus widely popularized in many laboratories.

  7. Deflection of a monochromatic THz beam by acousto-optic methods

    SciTech Connect

    Voloshinov, V B; Nikitin, P A; Gerasimov, V V; Choporova, Yu Yu; Knyazev, B A

    2013-12-31

    The possibility of controlled deflection of an electromagnetic THz beam of a free-electron laser by acousto-optic (AO) methods has been demonstrated for the first time. The material of the AO deflector was chosen to be single-crystal germanium, which has a fairly large refractive index (n = 4.0) and a relatively low absorption coefficient for electromagnetic waves. The absorption coefficient α in germanium is 0.75 ± 0.02 cm{sup -1} at a wavelength λ = 140 μm. The diffracted beam intensity is shown to be maximum at an effective AO interaction length l = 1/α. A diffraction efficiency of 0.05% at a travelling acoustic wave power of 1.0 W is experimentally obtained. It is established that a change in the ultrasonic frequency from 25 to 39 MHz leads to variation in the external Bragg angle in the range from 19.5° to 27.5°. At a fixed Bragg angle θ{sub B} = 22.4° the frequency band of diffraction is 4.2 ± 0.1 MHz and the angular range of laser beam scanning reaches 2.5° ± 0.5°. The results obtained indicate that AO interaction can be used for controlled deflection of electromagnetic THz beams. (terahertz radiation)

  8. A RAPIDLY-TUNABLE ACOUSTO-OPTIC SPECTROMETER FOR A SPACE ENVIRONMENT

    SciTech Connect

    D. THOMPSON; C. HEWITT; C. WILSON

    2000-08-01

    As a complement to our work developing rapidly-tunable ({approximately}10-100 kHz) CO{sub 2} lasers for differential absorption lidar (DIAL) applications,l we have developed a rapidly-tunable spectrometer. A rapid spectral diagnostic is critical for a high speed DIAL system, since analysis of the return signals depends on knowing the spectral purity of the transmitted beam. The spectrometer developed for our lidar system is based on a double-passed large- (75 mm) aperture acousto-optic deflector, a grating, and a fast single-element room temperature mercury-cadmium-telluride detector. The spectrometer has a resolution of {approximately}0.5 cm{sup {minus}1}, a tuning range of 9.0-11.4 pm, a random-access tuning speed of greater than 80 kHz and a S/N ratio of greater than 100:1. We describe the design and performance of this device, as well as of future devices featuring improved resolution, higher speed and easier and more robust alignment. We will also briefly discuss the applications and limitations of the technique in a space environment.

  9. The effect of scattering-medium parameters on signal magnitude under acousto-optic tomography

    NASA Astrophysics Data System (ADS)

    Zyuryukina, O. V.; Volkova, E. K.; Perchenko, M. I.; Solov'ev, A. P.

    2014-04-01

    We have experimentally studied the influence of scattering anisotropy parameter g of a medium on the magnitude of signal S (visualization parameter) at an ultrasonic frequency that is registered upon acoustooptic tomography. Aqueous solutions of mixtures of cream and skimmed milk with different ratios between them were used as scattering media. The optical properties of media (absorption coefficient μa and reduced scattering coefficient μ' S ) have been measured on a spectrophotometer (Perkin-Elmer Lambda 950 UV-VIS-NIR) using the inverse adding-doubling technique. As a result of the investigation, we have found that there is a certain correlation between the value of the scattering anisotropy parameter g of aqueous solutions of investigated mixtures and the percentage of the mixture in the aqueous solution, which ensures the required small value of extinction coefficient μ of the scattering medium. An increase in signal S has been revealed with increasing anisotropy parameter g of the medium at a invariable value of extinction coefficient μ. We have concluded that, to solve an inverse problem on the acousto-optic tomography, it is necessary to take into account possible changes in the g factor in scattering media, including biological ones.

  10. Acousto-optic tunable filter for dispersion characterization of time-domain optical coherence tomography systems.

    PubMed

    Chin, Catherine; Toadere, Florin; Feuchter, Thomas; Leick, Lasse; Moselund, Peter; Bradu, Adrian; Podoleanu, Adrian

    2016-07-20

    A broadband supercontinuum light source with an acousto-optic tunable filter (AOTF) are used to characterize dispersion in two time-domain OCT systems, at 850 and 1300 nm. The filter is designed to sweep across two spectral ranges, which are restricted here from 800 to 900 nm and from 1200 to 1500 nm, respectively. Dispersion compensation for 850 nm was achieved with a spectral delay line. Dispersion compensation for 1300 nm was achieved using BK 7 rod glasses in the reference arm. The AOTF allows evaluation of dispersion in under as well as overcompensated systems. The AOTF method is based on wavelength dependence of the optical path difference corresponding to the maximum strength of the interference signal recorded using a mirror as object. Comparison is made between the AOTF method and the more usual method based on measurement of the full width at half-maximum of the autocorrelation peak. This comparison shows that the AOTF method is more accurate in terms of evaluation of the dispersion left uncompensated after each adjustment. The AOTF method additionally provides information on the direction of dispersion compensation. PMID:27463927

  11. Tunable acousto-optic spectral imager for atmospheric composition measurements in the visible spectral domain.

    PubMed

    Dekemper, Emmanuel; Loodts, Nicolas; Van Opstal, Bert; Maes, Jeroen; Vanhellemont, Filip; Mateshvili, Nina; Franssens, Ghislain; Pieroux, Didier; Bingen, Christine; Robert, Charles; De Vos, Lieve; Aballea, Ludovic; Fussen, Didier

    2012-09-01

    We describe a new spectral imaging instrument using a TeO(2) acousto-optical tunable filter (AOTF) operating in the visible domain (450-900 nm). It allows for fast (~1 second), monochromatic (FWHM ranges from 0.6 nm at 450 nm to 3.5 nm at 800 nm) picture acquisition with good spatial resolution. This instrument was designed as a breadboard of the visible channel of a new satellite-borne atmospheric limb spectral imager, named the Atmospheric Limb Tracker for the Investigation of the Upcoming Stratosphere (ALTIUS), that is currently being developed. We tested its remote sensing capabilities by observing the dense, turbulent plume exhausted by a waste incinerator stack at two wavelengths sensitive to NO(2). An average value of 6.0±0.4×10(17) molecules cm(-2) has been obtained for the NO(2) slant column density within the plume, close to the stack outlet. Although this result was obtained with a rather low accuracy, it demonstrates the potential of spectral imaging by using AOTFs in remote sensing. PMID:22945175

  12. Deep-UV Based Acousto-Optic Tunable Filter for Spectral Sensing Applications

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.

    2006-01-01

    In this paper, recent progress made in the development of quartz and KDP crystal based acousto-optic tunable filters (AOTF) are presented. These AOTFs are developed for operation over deep-UV to near-UV wavelengths of 190 nm to 400 nm. Preliminary output performance measurements of quartz AOTF and design specifications of KDP AOTF are presented. At 355 nm, the quartz AOTF device offered approx.15% diffraction efficiency with a passband full-width-half-maximum (FWHM) of less than 0.0625 nm. Further characterization of quartz AOTF devices at deep-UV wavelengths is progressing. The hermetic packaging of KDP AOTF is nearing completion. The solid-state optical sources being used for excitation include nonlinear optics based high-energy tunable UV transmitters that operate around 320 nm and 308 nm wavelengths, and a tunable deep-UV laser operating over 193 nm to 210 nm. These AOTF devices have been developed as turn-key devices for primarily for space-based chemical and biological sensing applications using laser induced Fluorescence and resonance Raman techniques.

  13. A novel acousto-optic tunable filter for use in hyperspectral imaging systems

    NASA Astrophysics Data System (ADS)

    Stedham, C.; Draper, M.; Ward, J.; Wachman, E.; Pannell, C.

    2008-02-01

    The design and performance characteristics of a novel Acousto Optic Tunable Filter (AOTF) are presented. Particular attention has been paid to the reduction of optical side lobes, maximising the light throughput and achieving efficient wideband RF matching of a device for use in hyperspectral imaging systems. Conventional AOTFs are known to yield an optical pass band with side lobes at unacceptable levels of ~-10dB relative to the transmission peak. It is known that shaping the acoustic beam ("apodisation") can suppress the side lobe transmission of the AOTF and improve its imaging capabilities. Results of a novel electrode apodisation pattern are presented, reducing sidelobes to ~-25dB. This produces an AOTF which is capable of being placed in a diffraction limited optical system and introduces negligible amounts of image degradation. The large transducer area (associated with the large optical aperture) and acoustic impedance mismatch between the AO substrate (TeO II) and transducer (LiNbO 3) pose a challenge in achieving wideband RF performance. Acoustic mismatch between substrate and transducer has been addressed by the introduction of a special acoustic matching layer in the bond. The layer reduces dispersion in the transducer impedance easing broadband matching. The transducer has a low (<1 Ohm) radiation resistance which must be matched to the RF driver (typically 50 ohms). This very low impedance may be swamped by the parasitic impedances of the electrode, bond layers and wire bonds used for electrical connection. Thus, the transducer is split into series-connected sections to increase the "bare" impedance. We present results to show the performance increase that can be obtained this way.

  14. Development and application of a ray-based model of light propagation through a spherical acousto-optic lens

    PubMed Central

    Evans, Geoffrey J.; Kirkby, Paul A.; Nadella, K. M. Naga Srinivas; Marin, Bóris; Silver, R. Angus

    2016-01-01

    A spherical acousto-optic lens (AOL) consists of four acousto-optic deflectors (AODs) that can rapidly and precisely control the focal position of an optical beam in 3D space. Development and application of AOLs has increased the speed at which 3D random access point measurements can be performed with a two-photon microscope. This has been particularly useful for measuring brain activity with fluorescent reporter dyes because neuronal signalling is rapid and sparsely distributed in 3D space. However, a theoretical description of light propagation through AOLs has lagged behind their development, resulting in only a handful of simplified principles to guide AOL design and optimization. To address this we have developed a ray-based computer model of an AOL incorporating acousto-optic diffraction and refraction by anisotropic media. We extended an existing model of a single AOD with constant drive frequency to model a spherical AOL: four AODs in series driven with linear chirps. AOL model predictions of the relationship between optical transmission efficiency and acoustic drive frequency including second order diffraction effects closely matched experimental measurements from a 3D two-photon AOL microscope. Moreover, exploration of different AOL drive configurations identified a new simple rule for maximizing the field of view of our compact AOL design. By providing a theoretical basis for understanding optical transmission through spherical AOLs, our open source model is likely to be useful for comparing and improving different AOL designs, as well as identifying the acoustic drive configurations that provide the best transmission performance over the 3D focal region. PMID:26368449

  15. Study on the characteristics of an imaging spectrum system by means of an acousto-optic tunable filter

    NASA Astrophysics Data System (ADS)

    Cui, Yan; Cui, Dunjie; Tang, Jiu-Hua

    1993-11-01

    The spectrally agile staring sensor (SASS) is an instrument system that is able to acquire image and spectrum information simultaneously. We analyze the expression of SNR and overall performance of the SASS system consisting of an acousto-optic tunable filter and point out improvement methods and limiting factors of the system performance. The complete SASS system setup is constructed. By means of this setup, the theoretical analysis is verified and the image and spectrum information of the simulated target is obtained. These results demonstrate the ability of the SASS to acquire image and spectrum information.

  16. Optimization of the input losses in fiber-optic communications with an acousto-optic all-optical switch.

    PubMed

    Danilyan, A V; Shulgin, V A; Chernov, V E

    2006-06-20

    We study optical losses in the single-mode fiber system with an all-optical switch based on the anisotropic acousto-optic (AO) TeO(2) 2D deflector. It is shown, theoretically and experimentally, that the mismatch of the output-fiber mode profile and the switched optical beam shape depends significantly on the monochromaticity of the light beam and is determined by the frequency dispersion of the laser beam diffracted on a Bragg AO cell. A quantitative analysis of the dependence of the input optical losses on the spectral width of the light beam is presented. PMID:16778941

  17. Kilohertz generation of high contrast polarization states for visible femtosecond pulses via phase-locked acousto-optic pulse shapers

    SciTech Connect

    Seiler, Hélène; Walsh, Brenna; Palato, Samuel; Kambhampati, Patanjali; Thai, Alexandre; Forget, Nicolas; Crozatier, Vincent

    2015-09-14

    We present a detailed analysis of a setup capable of arbitrary amplitude, phase, and polarization shaping of broadband visible femtosecond pulses at 1 kHz via a pair of actively phase stabilized acousto-optic programmable dispersive filters arranged in a Mach-Zehnder interferometer geometry. The setup features phase stability values around λ/225 at 580 nm as well as degrees of polarization of at least 0.9 for any polarization state. Both numbers are important metrics to evaluate a setup's potential for applications based on polarization-shaped femtosecond pulses, such as fully coherent multi-dimensional electronic spectroscopy.

  18. Scanning microphotolysis: a new photobleaching technique based on fast intensity modulation of a scanned laser beam and confocal imaging.

    PubMed

    Wedekind, P; Kubitscheck, U; Peters, R

    1994-10-01

    The fluorescence photobleaching method has been widely used to study molecular transport in single living cells and other microsystems while confocal microscopy has opened new avenues to high-resolution, three-dimensional imaging. A new technique, scanning microphotolysis (Scamp), combines the potential of photobleaching, beam scanning and confocal imaging. A confocal scanning laser microscope was equipped with a sufficiently powerful laser and a novel device, the 'Scamper'. This consisted essentially of a filter changer, an acousto-optical modulator (AOM) and a computer. The computer was programmed to activate the AOM during scanning according to a freely defined image mask. As a result, almost any desired pattern could be bleached ('written') into fluorescent samples at high definition and then imaged ('read') at non-bleaching conditions, employing full confocal resolution. Furthermore, molecular transport could be followed by imaging the dissipation of bleach patterns. Experiments with living cells concerning dynamic processes in cytoskeletal filaments and the lateral mobility of membrane lipids suggest a wide range of potential biological applications. Thus, Scamp offers new possibilities for the optical manipulation and analysis of both technical and biological microsystems. PMID:7799426

  19. Multistage spectral polarimeter based on integrated acousto-optical Ti:LiNbO3 TE-TM converters for WDM system monitoring

    NASA Astrophysics Data System (ADS)

    Noe, Reinhold; Maucher, A.; Ricken, Raimund

    1999-04-01

    A 4-stage spectral polarimeter based on Ti:LiNbO3 acousto- optical TE-TM converters has been realized. It has about 20 dB stopband suppression and can measure polarimetric spectra as well as the time evolution of the state of polarization. A simple optical spectrum analyzer is also proposed.

  20. On the possibility of developing incoherent fibre-optic data transmission systems based on signal spectral coding with matched acousto-optical filters

    NASA Astrophysics Data System (ADS)

    Proklov, Valerii V.; Byshevski-Konopko, O. A.; Grigorievski, V. I.

    2013-06-01

    The scheme is suggested for developing the optical communication line based on the principle of code division of multiple access with matched acousto-optical filters and a 16-bit long Walsh sequence. Results of modelling show that such a line can operate if adjacent spectral lines are separated by at least double the Rayleigh criterion.

  1. A compact acousto-optic lens for 2D and 3D femtosecond based 2-photon microscopy

    PubMed Central

    Kirkby, Paul A.; Naga Srinivas, N.K.M.; Silver, R. Angus

    2010-01-01

    We describe a high speed 3D Acousto-Optic Lens Microscope (AOLM) for femtosecond 2-photon imaging. By optimizing the design of the 4 AO Deflectors (AODs) and by deriving new control algorithms, we have developed a compact spherical AOL with a low temporal dispersion that enables 2-photon imaging at 10-fold lower power than previously reported. We show that the AOLM can perform high speed 2D raster-scan imaging (>150 Hz) without scan rate dependent astigmatism. It can deflect and focus a laser beam in a 3D random access sequence at 30 kHz and has an extended focusing range (>137 μm; 40X 0.8NA objective). These features are likely to make the AOLM a useful tool for studying fast physiological processes distributed in 3D space PMID:20588506

  2. Integrated acousto-optic polarization converter in a ZX-cut LiNbO(3) waveguide superlattice.

    PubMed

    Yudistira, D; Janner, D; Benchabane, S; Pruneri, V

    2009-10-15

    We report an integrated acousto-optic polarization converter exploiting a novel surface acoustic superlattice (S-ASL) transducer. The S-ASL transducer is made of a ZX-cut periodically poled lithium niobate (PPLN) crystal with uniform coplanar electrodes for surface acoustic wave (SAW) generation. For a PPLN period of 20 microm the SAW is excited at an rf of about 190 MHz, while the phase matching occurs at an optical wavelength of around 1456 nm. The measured mode conversion efficiency of 90% at an input rf power of 1 W and the 3 dB optical bandwidth of 2.5 nm confirm the confinement of the SAW between the electrode gap and the constructive interaction along the whole 10 mm electrode length. PMID:19838274

  3. Pure electrical, highly-efficient and sidelobe free coherent Raman spectroscopy using acousto-optics tunable filter (AOTF)

    PubMed Central

    Meng, Zhaokai; Petrov, Georgi I.; Yakovlev, Vladislav V.

    2016-01-01

    Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. Stimulated Raman spectroscopy offers a substantial improvement in the signal-to-noise ratio but is often limited to a discrete number of wavelengths. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, a novel approach to a broadband stimulated Raman spectroscopy is demonstrated. The corresponding Raman shift covers the spectral range from 600 cm−1 to 4500 cm−1, sufficient for probing most vibrational Raman transitions. We validated the use of the new instrumentation to both coherent anti-Stokes scattering (CARS) and stimulated Raman scattering (SRS) spectroscopies. PMID:26828198

  4. Pure electrical, highly-efficient and sidelobe free coherent Raman spectroscopy using acousto-optics tunable filter (AOTF)

    NASA Astrophysics Data System (ADS)

    Meng, Zhaokai; Petrov, Georgi I.; Yakovlev, Vladislav V.

    2016-02-01

    Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. Stimulated Raman spectroscopy offers a substantial improvement in the signal-to-noise ratio but is often limited to a discrete number of wavelengths. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, a novel approach to a broadband stimulated Raman spectroscopy is demonstrated. The corresponding Raman shift covers the spectral range from 600 cm-1 to 4500 cm-1, sufficient for probing most vibrational Raman transitions. We validated the use of the new instrumentation to both coherent anti-Stokes scattering (CARS) and stimulated Raman scattering (SRS) spectroscopies.

  5. Pure electrical, highly-efficient and sidelobe free coherent Raman spectroscopy using acousto-optics tunable filter (AOTF).

    PubMed

    Meng, Zhaokai; Petrov, Georgi I; Yakovlev, Vladislav V

    2016-01-01

    Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. Stimulated Raman spectroscopy offers a substantial improvement in the signal-to-noise ratio but is often limited to a discrete number of wavelengths. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, a novel approach to a broadband stimulated Raman spectroscopy is demonstrated. The corresponding Raman shift covers the spectral range from 600 cm(-1) to 4500 cm(-1), sufficient for probing most vibrational Raman transitions. We validated the use of the new instrumentation to both coherent anti-Stokes scattering (CARS) and stimulated Raman scattering (SRS) spectroscopies. PMID:26828198

  6. Femtosecond terahertz time-domain spectroscopy at 36 kHz scan rate using an acousto-optic delay

    NASA Astrophysics Data System (ADS)

    Urbanek, B.; Möller, M.; Eisele, M.; Baierl, S.; Kaplan, D.; Lange, C.; Huber, R.

    2016-03-01

    We present a rapid-scan, time-domain terahertz spectrometer employing femtosecond Er:fiber technology and an acousto-optic delay with attosecond precision, enabling scanning of terahertz transients over a 12.4-ps time window at a waveform refresh rate of 36 kHz, and a signal-to-noise ratio of 1.7 × 105 / √{ H z } . Our approach enables real-time monitoring of dynamic THz processes at unprecedented speeds, which we demonstrate through rapid 2D thickness mapping of a spinning teflon disc at a precision of 10 nm/ √{ H z } . The compact, all-optical design ensures alignment-free operation even in harsh environments.

  7. All-fiber tunable laser based on an acousto-optic tunable filter and a tapered fiber.

    PubMed

    Huang, Ligang; Song, Xiaobo; Chang, Pengfa; Peng, Weihua; Zhang, Wending; Gao, Feng; Bo, Fang; Zhang, Guoquan; Xu, Jingjun

    2016-04-01

    An all-fiber tunable laser was fabricated based on an acousto-optic tunable filter and a tapered fiber. The structure was of a high signal-to-noise ratio, therefore, no extra gain flattening was needed in the laser. In the experiment, the wavelength of the laser could be tuned from 1532.1 nm to 1570.4 nm with a 3-dB bandwidth of about 0.2 nm. Given enough nonlinearity in the laser cavity, it could also generate a sliding-frequency pulse train. The laser gains advantages of fast tuning and agility in pulse generation, and its simple structure is low cost for practical applications. PMID:27137035

  8. Mid infra-red hyper-spectral imaging with bright super continuum source and fast acousto-optic tuneable filter for cytological applications.

    NASA Astrophysics Data System (ADS)

    Farries, Mark; Ward, Jon; Valle, Stefano; Stephens, Gary; Moselund, Peter; van der Zanden, Koen; Napier, Bruce

    2015-06-01

    Mid-IR imaging spectroscopy has the potential to offer an effective tool for early cancer diagnosis. Current development of bright super-continuum sources, narrow band acousto-optic tunable filters and fast cameras have made feasible a system that can be used for fast diagnosis of cancer in vivo at point of care. The performance of a proto system that has been developed under the Minerva project is described.

  9. Modern collinear LiNbO3 acousto-optical filter for optical spectroscopy: the exploration of efficiency and spectral resolution

    NASA Astrophysics Data System (ADS)

    Shcherbakov, A. S.; Arellanes, A. O.; Bertone, E.

    2016-02-01

    Our work is devoted to the collinear acousto-optical filter governed by the acoustic waves of finite amplitude. It represents a novel bulk-optical component, namely, the dispersive element for optical spectroscopy. This filter is based on specifically doped lithium niobate single crystal that unexpectedly works in the near ultraviolet range as well as this material usually works in the visible range. We examine the phenomena affecting the filter transmission efficiency and its resolution, i.e. the light-induced absorption and photorefraction. A new nonlinear approach is used to characterize performances of this collinear LiNbO3 acousto-optical filter exploiting our revealed specific acousto-optical nonlinearity. We have carried out the experiments with the collinear filter based on the congruent LiNbO3 crystal of 6.3 cm length at λ = 405 and 440 nm to verify our analysis and estimations. We also explore an opportunity to trade an amount of the efficiency to improve the spectral resolution. The transmission efficiency steeply increases with increasing light wavelength and with decreasing length of the filter, nevertheless the efficiency still remains higher than 30% in the near ultraviolet, if the spectral resolution is limited by δλ = 0.28-0.29 Å. Moreover, we demonstrate the possibility to reach a resolution as high as δλ = 0.12-0.15 Å (R > 24600), preserving at the same time an efficiency higher than 10% over the spectral interval that we considered. It looks like our filter holds the best to our knowledge experimentally confirmed spectral resolution for any collinear acousto-optical spectrometers dedicated to space/airborne operations.

  10. A novel collinear LiNbO3 acousto optical tunable filter with the improved range of transmission and spectral resolution

    NASA Astrophysics Data System (ADS)

    Arellanes, Adan Omar; Shcherbakov, Alexandre S.; Bertone, Emanuele

    2015-02-01

    This investigation represents a deep and advanced analysis of exploiting lithium niobate (LiNbO3) crystals for the collinear acousto-optical tunable filter (AOTF) in violet and near ultraviolet ranges. The selection of this material is motivated by its high birefringence, which is a key parameter for improving the resolution of AOTF. For this matter, we take into account all the important factors that can deteriorate the resolution in order to find extreme conditions for the best performances. In concrete, we analyze the well- known photorefraction effect accompanied by the light induced absorption in those ranges for the LiNbO3 crystals doped by selected materials. The best observed results have been obtained with magnesium (Mg) dopant in the congruent melt of LiNbO3, which also shifts the absorption edge far into the middle UV-range. This analysis had made it possible to formulate the physical criterion determining the enlarged practical limitations of the incident light power density. Together with previously studied non-uniformity and dispersion of the birefringence along the length of acousto-optical interaction in a crystal, we exploit the recently discovered and experimentally confirmed acousto-optical nonlinearity, which can improve the transmission function inherent in the collinear interaction via applying the acoustic waves of finite amplitude in the AOTF. As a result, the obtained spectral resolution is the best available for any collinear AOTF to our knowledge.

  11. Acousto-optic-tunable-filter-based spectropolarimetric imagers for medical diagnostic applications--instrument design point of view.

    PubMed

    Gupta, Neelam

    2005-01-01

    Compact optical imagers that can detect both spectral and polarization signatures are required in many biomedical applications. An acousto-optic-tunable-filter (AOTF)-based imager is ideally suited to provide both agile spectral and polarization signatures. Such an imager can be readily used for real-time in vivo medical diagnostic applications. We develop a family of small, robust, and programmable hyperspectral imagers operating from the ultraviolet (UV) to the long-wave IR (LWIR). Such imagers require minimal data processing because they can acquire images at only select wavelengths of interest. We use AOTFs made of KDP, TeO2, and TAS with Si-based CCD, InGaAs, InSb, and HgCdTe cameras to cover different spectral regions from the UV to the LWIR. Operation of each of these imagers and image acquisition is computer controlled. The most developed imager covers the visible to near-infrared (VNIR) region from 400 to 900 nm, with a 10-nm spectral resolution at 600 nm, it uses an electronically tunable TeO2 AOTF as a bandpass filter, and a nematic liquid crystal retarder to change polarization. We describe our concept in the development of these imagers and present new results obtained using the VNIR imager. PMID:16292960

  12. Bit error rate optimization of an acousto-optic tracking system for free-space laser communications

    NASA Astrophysics Data System (ADS)

    Sofka, J.; Nikulin, V.

    2006-02-01

    Optical communications systems have been gaining momentum with the increasing demand for transmission bandwidth in the last several years. Optical cable based solutions have become an attractive alternative to copper based system in the most bandwidth demanding applications due to increased bandwidth and longer inter-repeater distances. The promise of similar benefits over radio communications systems is driving the research into free space laser communications. Along with increased communications bandwidth, a free space laser communications system offers lower power consumption and the possibility for covert data links due to the concentration of the energy of the laser into a narrow beam. A narrow beam, however, results in a requirement for much more accurate and agile steering, so that a data link can be maintained in a scenario of communication platforms in relative motion or in the presence of vibrations. This paper presents a laser beam tracking system employing an acousto-optic cell capable of deflecting a laser beam at a very high rate (order of tens of kHz). The tracking system is subjected to vibrations to simulate a realistic implementation, resulting in the increase of BER. The performance of the system can be significantly improved through digital control. A constant gain controller is complemented by a Kalman filter the parameters of which are optimized to achieve the lowest possible BER for a given vibrations spectrum.

  13. The Aerosol Limb Imager: acousto-optic imaging of limb-scattered sunlight for stratospheric aerosol profiling

    NASA Astrophysics Data System (ADS)

    Elash, B. J.; Bourassa, A. E.; Loewen, P. R.; Lloyd, N. D.; Degenstein, D. A.

    2016-03-01

    The Aerosol Limb Imager (ALI) is an optical remote sensing instrument designed to image scattered sunlight from the atmospheric limb. These measurements are used to retrieve spatially resolved information of the stratospheric aerosol distribution, including spectral extinction coefficient and particle size. Here we present the design, development and test results of an ALI prototype instrument. The long-term goal of this work is the eventual realization of ALI on a satellite platform in low earth orbit, where it can provide high spatial resolution observations, both in the vertical and cross-track. The instrument design uses a large-aperture acousto-optic tunable filter (AOTF) to image the sunlit stratospheric limb in a selectable narrow wavelength band ranging from the visible to the near infrared. The ALI prototype was tested on a stratospheric balloon flight from the Canadian Space Agency (CSA) launch facility in Timmins, Canada, in September 2014. Preliminary analysis of the hyperspectral images indicates that the radiance measurements are of high quality, and we have used these to retrieve vertical profiles of stratospheric aerosol extinction coefficient from 650 to 1000 nm, along with one moment of the particle size distribution. Those preliminary results are promising and development of a satellite prototype of ALI within the Canadian Space Agency is ongoing.

  14. A rapid excitation-emission matrix fluorometer utilizing supercontinuum white light and acousto-optic tunable filters

    NASA Astrophysics Data System (ADS)

    Wang, Wenbo; Wu, Zhenguo; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan

    2016-06-01

    Scanning speed and coupling efficiency of excitation light to optic fibres are two major technical challenges that limit the potential of fluorescence excitation-emission matrix (EEM) spectrometer for on-line applications and in vivo studies. In this paper, a novel EEM system, utilizing a supercontinuum white light source and acousto-optic tunable filters (AOTFs), was introduced and evaluated. The supercontinuum white light, generated by pumping a nonlinear photonic crystal fiber with an 800 nm femtosecond laser, was efficiently coupled into a bifurcated optic fiber bundle. High speed EEM spectral scanning was achieved using AOTFs both for selecting excitation wavelength and scanning emission spectra. Using calibration lamps (neon and mercury argon), wavelength deviations were determined to vary from 0.18 nm to -0.70 nm within the spectral range of 500-850 nm. Spectral bandwidth for filtered excitation light broadened by twofold compared to that measured with monochromatic light between 650 nm and 750 nm. The EEM spectra for methanol solutions of laser dyes were successfully acquired with this rapid fluorometer using an integration time of 5 s.

  15. Finite-difference time-domain simulation of compact acousto-optic filters based on multireflection beam expanding

    SciTech Connect

    Tsarev, Andrei V

    2007-04-30

    The results of numerical simulation of acousto-optic (AO) tunable filters of a new type based on multireflection beam expanding in waveguide structures are discussed. Planar waveguide filters based on thin chalcogenide (As{sub 2}S{sub 3}) films of lithium niobate (LiNbO{sub 3}) are considered. The operation of filters is analysed by the finite-difference time-domain (FDTD) method by using the license FullWAVE software package (RSoft Design Group, Inc.). It is shown that AO filters have very good dispersion properties and AO filters of extremely small size provide a narrow filtration line within the tuning range of more than 100 nm (at a wavelength of 1.54 {mu}m). It is important that the normalised linewidth (measured in units of the reciprocal filter length) is an order of magnitude smaller than the theoretical limit for AO filters produced from the same material in the conventional way, without the use of multireflection beam expanding. (acoustooptics)

  16. Characterizing the performances of an advanced acousto-optical filter exploiting the collinear calcium molybdate crystalline cell

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Alexandre S.; Maximov, Je.; Sanchez Lucero, Daniel; Sanchez Perez, Karla J.

    2011-03-01

    In 1970 - 80s, novel optical spectral devices, electronically tunable acousto-optical filters (AOFs) had been proposed and developed. During the years gone AOFs have been remarkably progressed, and now they are widely exploited, for instance, in astrophysical observations. Schematically, AOFs can be separated on collinear and non-collinear filters, depending on the relative directions of passing the waves through crystalline cell, as well as on sequential and parallel ones, depending on the algorithm of spectrum analysis. Their features are characterized by the amplitude and spectral parameters. Here, we consider a few estimations of an advanced collinear AOF based on calcium molybdate single-crystal. In principle, this new AOF with a 15-microsecond time-aperture operates over all the visible range exhibiting 60%-efficiency at the electric power 1.0 W. Direct square-law dependence for crystal's length and inverse square-law dependence for its bandwidth on this minimal size make possible optimizing this advanced collinear AOF.

  17. A rapid excitation-emission matrix fluorometer utilizing supercontinuum white light and acousto-optic tunable filters.

    PubMed

    Wang, Wenbo; Wu, Zhenguo; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan

    2016-06-01

    Scanning speed and coupling efficiency of excitation light to optic fibres are two major technical challenges that limit the potential of fluorescence excitation-emission matrix (EEM) spectrometer for on-line applications and in vivo studies. In this paper, a novel EEM system, utilizing a supercontinuum white light source and acousto-optic tunable filters (AOTFs), was introduced and evaluated. The supercontinuum white light, generated by pumping a nonlinear photonic crystal fiber with an 800 nm femtosecond laser, was efficiently coupled into a bifurcated optic fiber bundle. High speed EEM spectral scanning was achieved using AOTFs both for selecting excitation wavelength and scanning emission spectra. Using calibration lamps (neon and mercury argon), wavelength deviations were determined to vary from 0.18 nm to -0.70 nm within the spectral range of 500-850 nm. Spectral bandwidth for filtered excitation light broadened by twofold compared to that measured with monochromatic light between 650 nm and 750 nm. The EEM spectra for methanol solutions of laser dyes were successfully acquired with this rapid fluorometer using an integration time of 5 s. PMID:27370436

  18. Research Cooperation between Catholic Universityof Leuven Campus Kortrijk and University of Gdansk in Acousto-optics - A Historical Recollection1

    NASA Astrophysics Data System (ADS)

    Śliwiński, A.

    A short review of results achieved during many years of cooperation between the Belgian group of KULAK and the Polish group of Gdansk University (UG) is presented as a tribute to Oswald Leroy for his significant contribution. The scientific research in examination of ultrasonic light interaction phenomena was the area of this fruitful joint collaboration since 1971. Oswald Leroy's crucial role in the cooperation is emphasized and some historical events are recalled. His original theoretical papers predicted new theoretical phenomena which were successfully experimentally verified in the A. O. laboratory at the University of Gdansk. Later on, they have become inspiration for further fundamental search in acousto-optics. Members of Gdansk AO group many times visited Kortrijk to work together on ULD phenomena or attending seminars and symposia organized in Belgium and the Belgian group took part in the international Spring Schools and Applications systematically organized by Gdansk University as the triennial meetings since 1980. Leroy's contribution to the mutual co-operation has been recognized as so important and significant that in 1991 he was honored with the Doctorate Honoris Causa of the University of Gdansk.

  19. Narrow linewidth broadband tunable semiconductor laser at 840 nm with dual acousto-optic tunable configuration for OCT applications

    NASA Astrophysics Data System (ADS)

    Chamorovskiy, Alexander; Shramenko, Mikhail V.; Lobintsov, Andrei A.; Yakubovich, Sergei D.

    2016-03-01

    We demonstrate a tunable narrow linewidth semiconductor laser for the 840 nm spectral range. The laser has a linear cavity comprised of polarization maintaining (PM) fiber. A broadband semiconductor optical amplifier (SOA) in in-line fiber-coupled configuration acts as a gain element. It is based on InGaAs quantum-well (QW) active layer. SOA allows for tuning bandwidth exceeding 25 nm around 840 nm. Small-signal fiber-to-fiber gain of SOA is around 30 dB. A pair of acousto-optic tunable filters (AOTF) with a quasi-collinear interaction of optical and acoustic waves are utilized as spectrally selective elements. AOTF technology benefits in continuous tuning, broadband operation, excellent reproducibility and stability of the signal, as well as a high accuracy of wavelength selectivity due to the absence of mechanically moving components. A single AOTF configuration has typical linewidth in 0.05-0.15 nm range due to a frequency shift obtained during each roundtrip. A sequential AOTF arrangement enables instantaneous linewidth generation of <0.01 nm by compensating for this shift. Linewidth as narrow as 0.0036 nm is observed at 846 nm wavelength using a scanning Fabry-Perot interferometer with 50 MHz spectral resolution. Output power is in the range of 1 mW. While the majority of commercial tunable sources operate in 1060-1550 nm spectral ranges, the 840 nm spectral range is beneficial for optical coherence tomography (OCT). The developed narrow linewidth laser can be relevant for OCT with extended imaging depth, as well as spectroscopy, non-destructive testing and other applications.

  20. Characterization of the non-collinear acousto-optical cell based on calomel (Hg2Cl2) crystal and operating within the two-phonon light scattering

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Alexandre S.; Arellanes, Adan O.

    2016-03-01

    Performances of any system for data processing based on acousto-optical technique are mainly determined by parameters of the acousto-optical cell (AOC) exploited within the schematic arrangement. Here, basic properties of the AOC, involved into a novel processor for precise optical spectrum analysis dedicated to modern astrophysical applications, are considered. Because potential applications of this processor will be focused on investigations in extra-galactic astronomy as well as studies of extra-solar planets, an advanced regime of the non-collinear two-phonon light scattering has been elaborated for spectrum analysis with significantly improved spectral resolution. Under similar uprated requirements, the AOC, based on that specific regime in the calomel (Hg2Cl2) crystal, had been chosen, and its parameters were analyzed theoretically and verified experimentally. Then, the adequate approach to estimating the frequency/spectral bandwidth and spectral resolution had been developed. The bandwidth was calculated and experimentally realized with the additionally involved tilt angle of light incidence, allowing variations for acoustic frequencies. The resolution was characterized taking into account its doubling peculiar to the nonlinear two-phonon mechanism of light scattering. Proof-of-principle experiments were performed with the calomel AOC of 52 mm optical aperture, providing ~94% efficiency in the transmitted light due to the slow-shear acoustic mode of finite amplitude (the acoustic power density ~150 mW/mm2) with the velocity of 0.347×105 cm/s at the radio-wave acoustic frequency ~71 MHz. As a result, we have obtained the spectral resolution <0.235 Å within the spectral bandwidth <290 Å that looks as the best one can mention at the moment in acousto-optics.

  1. Characterization of the optical sub-system in an advanced prototype of a new acousto-optical spectrometer for the Mexican Large Millimeter Telescope

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Alexandre S.; Sanchez Lucero, Daniel; Laskin, Alexander

    2011-09-01

    A few optically matched by each other sub-systems related to an advanced prototype of acousto-optical spectrometer for radio-astronomy are analyzed jointly. Rather precise control over the incident light polarization should be assured in the scheme together with a required expanding of the incident light beam. Moreover, the needed light-beam apodization, suppressing side lobes within registration of each individual resolvable spot and increasing the dynamic range of spectrometer, has to be taken into account as well. The current stage of analysis related to afore-mentioned problems as well as the results of trial experiments are presented.

  2. Improvement in the synchronization between the radio frequency signal and the image detector in an acousto-optic tunable filter imaging spectrometer.

    PubMed

    Zhao, Huijie; Li, Chongchong; Zhang, Ying; Xu, Zefu

    2014-04-10

    An improved synchronization between the radio frequency (RF) signal and the image detector in an acousto-optic tunable filter (AOTF) imaging spectrometer is proposed to optimize power consumption and eliminate image smear. The RF signal is controlled on and off alternately to match the exposure of the image sensor. This scheme reduces the RF power and rejects the light illumination on the image sensor in the interval of charge transfer. An experiment using a visible AOTF, a frame transfer charge-coupled device camera, and an incandescent lamp is conducted for demonstration. The average RF power decreases 7.6%, and the image smear is eliminated. PMID:24787400

  3. A modeling-based assessment of acousto-optic sensing for monitoring high-intensity focused ultrasound lesion formation

    NASA Astrophysics Data System (ADS)

    Adams, Matthew Tyler

    Real-time acousto-optic (AO) sensing---a dual-wave modality that combines ultrasound with diffuse light to probe the optical properties of turbid media---has been demonstrated to non-invasively detect changes in ex vivo tissue optical properties during high-intensity focused ultrasound (HIFU) exposure. The AO signal indicates the onset of lesion formation and predicts resulting lesion volumes. Although proof-of-concept experiments have been successful, many of the underlying parameters and mechanisms affecting thermally induced optical property changes and the AO detectability of HIFU lesion formation are not well understood. In thesis, a numerical simulation was developed to model the AO sensing process and capture the relevant acoustic, thermal, and optical transport processes. The simulation required data that described how optical properties changed with heating. Experiments were carried out where excised chicken breast was exposed to thermal bath heating and changes in the optical absorption and scattering spectra (500 nm--1100 nm) were measured using a scanning spectrophotometer and an integrating sphere assembly. Results showed that the standard thermal dose model currently used for guiding HIFU treatments needs to be adjusted to describe thermally induced optical property changes. To model the entire AO process, coupled models were used for ultrasound propagation, tissue heating, and diffusive light transport. The angular spectrum method was used to model the acoustic field from the HIFU source. Spatial-temporal temperature elevations induced by the absorption of ultrasound were modeled using a finite-difference time-domain solution to the Pennes bioheat equation. The thermal dose model was then used to determine optical properties based on the temperature history. The diffuse optical field in the tissue was then calculated using a GPU-accelerated Monte Carlo algorithm, which accounted for light-sound interactions and AO signal detection. The simulation was

  4. Noise tolerance in wavelength-selective switching of optical differential quadrature-phase-shift-keying pulse train by collinear acousto-optic devices.

    PubMed

    Goto, Nobuo; Miyazaki, Yasumitsu

    2014-06-01

    Optical switching of high-bit-rate quadrature-phase-shift-keying (QPSK) pulse trains using collinear acousto-optic (AO) devices is theoretically discussed. Since the collinear AO devices have wavelength selectivity, the switched optical pulse trains suffer from distortion when the bandwidth of the pulse train is comparable to the pass bandwidth of the AO device. As the AO device, a sidelobe-suppressed device with a tapered surface-acoustic-wave (SAW) waveguide and a Butterworth-type filter device with a lossy SAW directional coupler are considered. Phase distortion of optical pulse trains at 40 to 100  Gsymbols/s in QPSK format is numerically analyzed. Bit-error-rate performance with additive Gaussian noise is also evaluated by the Monte Carlo method. PMID:24922411

  5. Application of independent component analysis method in real-time spectral analysis of gaseous mixtures for acousto-optical spectrometers based on differential optical absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Fadeyev, A. V.; Pozhar, V. E.

    2012-10-01

    It is discussed the reliability problem of time-optimized method for remote optical spectral analysis of gas-polluted ambient air. The method based on differential optical absorption spectroscopy (DOAS) enables fragmentary spectrum registration (FSR) and is suitable for random-spectral-access (RSA) optical spectrometers like acousto-optical (AO) ones. Here, it is proposed the algorithm based on statistical method of independent component analysis (ICA) for estimation of a correctness of absorption spectral lines selection for FSR-method. Implementations of ICA method for RSA-based real-time adaptive systems are considered. Numerical simulations are presented with use of real spectra detected by the trace gas monitoring system GAOS based on AO spectrometer.

  6. Effect of direction of incident light on the basic performance of a TeO2 acousto-optic tunable filter.

    PubMed

    Wang, Pengchong; Zhang, Zhonghua

    2016-08-01

    The selection of the ultrasonic polar angle is vitally important to the performance of an acousto-optic tunable filter (AOTF). The effects of ultrasonic angle on various properties of AOTFs were studied. Then, according to the selected ultrasonic angle, the changes of internal and external separation angles were analyzed in detail when the light was incident upon the crystal surface in two different ways. Additionally, the drift of diffracted light caused by chromatic aberration was analyzed, and an appropriate compensation wedge angle was calculated by the improved derivation formula. The external separation angle increased obviously after placing a wedge angle on the output end. Finally, the effect of incident beam with a cone angle on spectral bandwidth and diffraction efficiency is discussed. PMID:27505364

  7. Acousto-optic Q-switching laser performance of Yb:GdCa(4)O(BO(3))(3)crystal.

    PubMed

    Chen, Xiaowen; Xu, Honghao; Guo, Yunfeng; Han, Wenjuan; Yu, Haohai; Zhang, Huaijin; Liu, Junhai

    2015-08-20

    We report on the active Q-switching laser performance of Yb:GdCa4O(BO3)3 crystal, demonstrated by employing an acousto-optic Q-switch in a compact plano-concave resonator. Stable repetitively Q-switched operation is achieved with pulse repetition rates varying from 30 to 0.2 kHz, producing an average output power of 10.2 W at 1027.5 nm at 30 kHz of repetition rate, with an optical-to-optical efficiency of 30%. The maximum pulse energy generated at the lowest repetition rate of 0.2 kHz is 4.75 mJ, with a pulse width being 11 ns, gives rise to a peak power that amounts to 432 kW. PMID:26368745

  8. Monitoring synaptic and neuronal activity in 3D with synthetic and genetic indicators using a compact acousto-optic lens two-photon microscope☆

    PubMed Central

    Fernández-Alfonso, Tomás; Nadella, K.M. Naga Srinivas; Iacaruso, M. Florencia; Pichler, Bruno; Roš, Hana; Kirkby, Paul A.; Silver, R. Angus

    2014-01-01

    Background Two-photon microscopy is widely used to study brain function, but conventional microscopes are too slow to capture the timing of neuronal signalling and imaging is restricted to one plane. Recent development of acousto-optic-deflector-based random access functional imaging has improved the temporal resolution, but the utility of these technologies for mapping 3D synaptic activity patterns and their performance at the excitation wavelengths required to image genetically encoded indicators have not been investigated. New method Here, we have used a compact acousto-optic lens (AOL) two-photon microscope to make high speed [Ca2+] measurements from spines and dendrites distributed in 3D with different excitation wavelengths (800–920 nm). Results We show simultaneous monitoring of activity from many synaptic inputs distributed over the 3D arborisation of a neuronal dendrite using both synthetic as well as genetically encoded indicators. We confirm the utility of AOL-based imaging for fast in vivo recordings by measuring, simultaneously, visually evoked responses in 100 neurons distributed over a 150 μm focal depth range. Moreover, we explore ways to improve the measurement of timing of neuronal activation by choosing specific regions within the cell soma. Comparison with existing methods These results establish that AOL-based 3D random access two-photon microscopy has a wider range of neuroscience applications than previously shown. Conclusions Our findings show that the compact AOL microscope design has the speed, spatial resolution, sensitivity and wavelength flexibility to measure 3D patterns of synaptic and neuronal activity on individual trials. PMID:24200507

  9. Quantitative analysis of anaerobic oxidation of methane (AOM) in marine sediments: A modeling perspective

    NASA Astrophysics Data System (ADS)

    Regnier, P.; Dale, A. W.; Arndt, S.; LaRowe, D. E.; Mogollón, J.; Van Cappellen, P.

    2011-05-01

    Recent developments in the quantitative modeling of methane dynamics and anaerobic oxidation of methane (AOM) in marine sediments are critically reviewed. The first part of the review begins with a comparison of alternative kinetic models for AOM. The roles of bioenergetic limitations, intermediate compounds and biomass growth are highlighted. Next, the key transport mechanisms in multi-phase sedimentary environments affecting AOM and methane fluxes are briefly treated, while attention is also given to additional controls on methane and sulfate turnover, including organic matter mineralization, sulfur cycling and methane phase transitions. In the second part of the review, the structure, forcing functions and parameterization of published models of AOM in sediments are analyzed. The six-orders-of-magnitude range in rate constants reported for the widely used bimolecular rate law for AOM emphasizes the limited transferability of this simple kinetic model and, hence, the need for more comprehensive descriptions of the AOM reaction system. The derivation and implementation of more complete reaction models, however, are limited by the availability of observational data. In this context, we attempt to rank the relative benefits of potential experimental measurements that should help to better constrain AOM models. The last part of the review presents a compilation of reported depth-integrated AOM rates (ΣAOM). These rates reveal the extreme variability of ΣAOM in marine sediments. The model results are further used to derive quantitative relationships between ΣAOM and the magnitude of externally impressed fluid flow, as well as between ΣAOM and the depth of the sulfate-methane transition zone (SMTZ). This review contributes to an improved understanding of the global significance of the AOM process, and helps identify outstanding questions and future directions in the modeling of methane cycling and AOM in marine sediments.

  10. Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies.

    PubMed

    Tadesse, Semere Ayalew; Li, Mo

    2014-01-01

    Light-sound interactions have long been exploited in various acousto-optic devices based on bulk crystalline materials. Conventionally, these devices operate in megahertz frequency range where the acoustic wavelength is much longer than the optical wavelength and a long interaction length is required to attain significant coupling. With nanoscale transducers, acoustic waves with sub-optical wavelengths can now be excited to induce strong acousto-optic coupling in nanophotonic devices. Here we demonstrate microwave frequency surface acoustic wave transducers co-integrated with nanophotonic resonators on piezoelectric aluminum nitride substrates. Acousto-optic modulation of the resonance modes at above 10 GHz with the acoustic wavelength significantly below the optical wavelength is achieved. The phase and modal matching conditions in this scheme are investigated for efficient modulation. The new acousto-optic platform can lead to novel optical devices based on nonlinear Brillouin processes and provides a direct, wideband link between optical and microwave photons for microwave photonics and quantum optomechanics. PMID:25400144

  11. Advanced collinear LiNbO3 acousto-optical filter for astrophysical spectroscopy in the near-ultraviolet: exploring high-spectral resolution

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Alexandre S.; Arellanes, Adán Omar; Bertone, Emanuele

    2015-10-01

    We explore the potentiality of using an advanced collinear LiNbO3 acousto-optical filter as a dispersive element for a high-resolution optical spectrograph. Our analysis is focused on weak optical signals in the blue to near-ultraviolet range accessible to ground-based facilities. We examine the phenomenon affecting the filter transmission efficiency and its spectral resolution, namely, the light-induced absorption and photorefraction. A new nonlinear approach is used to determine the performance of this collinear LiNbO3 filter governed by acoustic waves of finite amplitude. The highest available spectral resolution attains δλ=0.15 Å at λ=370 nm (the resolving power R˜25,000), with an efficiency of 11%, or δλ=0.18 Å at λ=532 nm (R˜30,000), with an efficiency of 33%. A slight decrease in the spectral resolution would imply a significant increase in transmission efficiency. Then, we carried out proof of principle experiments with the collinear filter based on the congruent LiNbO3 crystal of 6.3-cm length at λ=405 and 440 nm to verify our analysis and estimations. Potential applications are tackling many issues in astronomy, from detailed abundance analysis in a variety of targets to precise radial velocity measurement.

  12. Diode-pumped acousto-optically Q-switched high-repetition-rate Nd:YAG lasers at 946 and 473 nm by intracavity frequency-doubling

    NASA Astrophysics Data System (ADS)

    Chen, F.; Yu, X.; Guo, J.; Guo, L. H.; Yang, G. L.; Xie, J. J.; Zhang, L. M.; Geng, Y. M.; Li, S. M.; Li, D. J.; Shao, C. L.; Meng, F. J.; Zhang, C. S.; Yan, R. P.

    2011-10-01

    A diode-pumped acousto-optically (AO) Q-switched high-repetition-rate Nd:YAG lasers at 946 and 473 nm by intracavity frequency-doubling were reported in this paper. Using a compact V-type laser cavity, a maximum average output power of 4.5 W 946 nm laser was obtained at an operating repetition rate of 10 kHz, corresponding to an optical conversion efficiency of 10.5% and a slope efficiency of 15.6%. With a BiBO crystal as the intracavity frequency-doubler, 1.35 W 473 nm pulsed laser was achieved at 10 kHz. The peak power of the Q-switched blue pulse was up to 4.1 kW, with a pulse width of 33.1 ns. Then, the long-term power instability was less than 1%. Moreover, stable pulsed operation of 946 nm and 473 nm lasers can even reach 50 kHz.

  13. Efficient diode-pumped acousto-optic Q-switched Er:Yb:GdAl(3)(BO(3))(4) pulse laser at 1522  nm.

    PubMed

    Chen, Y J; Lin, Y F; Huang, J H; Gong, X H; Luo, Z D; Huang, Y D

    2015-11-01

    End-pumped by a continuous-wave 976 nm diode laser, efficient 1522 nm laser operation was demonstrated in an Er:Yb:GdAl(3)(BO(3))(4) crystal when a sapphire crystal was used as a heat diffuser. A continuous-wave 1522 nm laser with a maximum output power of 750 mW and slope efficiency of 36% was realized at an absorbed pump power of 4.1 W. The pulse performances of an acousto-optic Q-switched laser with various repetition frequencies were investigated in detail. In a repetition frequency range of 1-10 kHz, 1522 nm pulse lasers with a slope efficiency of about 10%, peak output power at the kilowatt level, and width of about 50 ns were first obtained in an Er:Yb:GdAl(3)(BO(3))(4) crystal pumped by a continuous-wave diode laser. The results indicate that the crystal is a promising gain medium for an actively Q-switched 1.5 μm laser. PMID:26512485

  14. Acoustic waveguide technique for sensing incipient faults in underground power-transmission cables: Including acousto-optic techniques

    NASA Astrophysics Data System (ADS)

    Harrold, R. T.

    1981-09-01

    Theoretical and practical studies were made of both the acoustic emission, spectrum signatures associated with underground cable incipient faults, and the attenuation of acoustic waves in waterfilled metal tubes used as waveguided. Based on critical data, it can be estimated that in favorable circumstances, the acoustic waveguide system would only be useful for sensing incipient faults in underground cables of approx. 800 meters of less in length. A system were investigated which acoustic emissions from cable incipient faults impinge on a fiber-optic lightguide and locally change its refractive index and modulate laser light transmitted along the light guide. Experiments based on this concept show that is is possible t sense acoustic emissions with energy levels below on micro-joule. A test of this system using a section of compressed gas-insulated cable with an internal flashover was successfully carried out.

  15. AOM optimization with ultra stable high power CO2 lasers for fast laser engraving

    NASA Astrophysics Data System (ADS)

    Bohrer, Markus

    2015-05-01

    A new ultra stable CO2 laser in carbon fibre resonator technology with an average power of more than 600W has been developed especially as basis for the use with AOMs. Stability of linear polarisation and beam pointing stability are important issues as well as appropriate shaping of the incident beam. AOMs are tested close to the laser-induced damage threshold with pulses on demand close to one megahertz. Transversal and rotational optimization of the AOMs benefits from the parallel-kinematic principle of a hexapod used for this research.

  16. MO-A-BRD-01: An Investigation of the Dynamic Response of a Novel Acousto-Optic Liquid Crystal Detector for Full-Field Transmission Ultrasound Breast Imaging

    SciTech Connect

    Rosenfield, J.R.; La Riviere, P.J.; Sandhu, J.S.

    2014-06-15

    Purpose: To characterize the dynamic response of a novel acousto-optic (AO) liquid crystal detector for high-resolution transmission ultrasound breast imaging. Transient and steady-state lesion contrast were investigated to identify optimal transducer settings for our prototype imaging system consistent with the FDA limits of 1 W/cm{sup 2} and 50 J/cm{sup 2} on the incident acoustic intensity and the transmitted acoustic energy flux density. Methods: We have developed a full-field transmission ultrasound breast imaging system that uses monochromatic plane-wave illumination to acquire projection images of the compressed breast. The acoustic intensity transmitted through the breast is converted into a visual image by a proprietary liquid crystal detector operating on the basis of the AO effect. The dynamic response of the AO detector in the absence of an imaged breast was recorded by a CCD camera as a function of the acoustic field intensity and the detector exposure time. Additionally, a stereotactic needle biopsy breast phantom was used to investigate the change in opaque lesion contrast with increasing exposure time for a range of incident acoustic field intensities. Results: Using transducer voltages between 0.3 V and 0.8 V and exposure times of 3 minutes, a unique one-to-one mapping of incident acoustic intensity to steady-state optical brightness in the AO detector was observed. A transfer curve mapping acoustic intensity to steady-state optical brightness shows a high-contrast region analogous to the linear portion of the Hurter-Driffield curves of radiography. Using transducer voltages between 1 V and 1.75 V and exposure times of 90 s, the lesion contrast study demonstrated increasing lesion contrast with increasing breast exposure time and acoustic field intensity. Lesion-to-background contrast on the order of 0.80 was observed. Conclusion: Maximal lesion contrast in our prototype system can be obtained using the highest acoustic field intensity and the

  17. Numerical analysis of first-order acousto-optic Bragg diffraction of profiled optical beams using open-loop transfer functions

    NASA Astrophysics Data System (ADS)

    Chatterjee, Monish R.; Almehmadi, Fares S.

    2014-03-01

    In standard acousto-optic Bragg analysis, the incident light and sound beams are assumed to be uniform plane waves (with constant profiles) leading to the results based on standard weak interaction theory. As a follow-up to earlier work dealing with nonuniform incident optical beams, we revisit the problem of Bragg diffraction under nonuniform profiles, and include Gaussian, third-order Hermite-Gaussian, and zeroth-order Bessel profiles in our investigation, along with a few others. The first-order diffracted beam is examined (using a transfer function formalism based on angular spectra) under several parametric limits [such as the Klein-Cook parameter Q, the effective profile width, and the optical phase-shift parameter (α) in the sound cell]. Wherever feasible, the numerical results are compared with analytic theory. The scattered first-order profile output versus the optical phase-shift appears to maintain behavior similar to the known first-order characteristics (sin2 in intensity) encountered for the uniform incident beam case. It is observed, however, that such conformity exists seemingly only at relatively small values of Q (typically about 20 to 50). At higher Qs, on the other hand (where one would otherwise expect behavior closer to standard Bragg theory based on large Qs), it is found that the first-order intensity deviates substantially from the expected sin2- (or related) pattern. This deviation actually becomes more severe at even higher Qs. Additionally, the output profiles at higher Qs are also found to be distorted relative to the incident profiles. These results, though anomalous, are nevertheless generally compatible with earlier studies. Based on the transfer function theory, it is also known that for very large optical phase shifts (i.e., when α goes to infinity), the scattered first-order output for a Gaussian profile undergoes an axial (spatial) shift past the output plane of the sound cell. This predicted result is corroborated in our

  18. Theoretical study of cw to short pulse conversion in an active cw-injected ring cavity with a Yb3+:YAG amplifier.

    PubMed

    Huang, Zhiyun; Bourdet, Gilbert L

    2007-05-10

    The short laser pulse generated from an active cw-injected ring cavity with Yb3+:YAG crystal, which is treated as the homogeneously broadened amplifier, is studied theoretically. Based on the derived results, the impacts of the amplifier length, the seeding laser intensity and frequency, the pump intensity, the efficiency of the acousto-optic modulator (AOM), and the frequency shift generated by the AOM on the performance of the laser pulse are analyzed. PMID:17446920

  19. Continuous wave operation of quantum cascade lasers with frequency-shifted feedback

    NASA Astrophysics Data System (ADS)

    Lyakh, A.; Barron-Jimenez, R.; Dunayevskiy, I.; Go, R.; Tsvid, G.; Patel, C. Kumar N.

    2016-01-01

    Operation of continuous wave quantum cascade lasers with a frequency-shifted feedback provided by an acousto-optic modulator is reported. Measured linewidth of 1.7 cm-1 for these devices, under CW operating conditions, was in a good agreement with predictions of a model based on frequency-shifted feedback seeded by spontaneous emission. Linewidth broadening was observed for short sweep times, consistent with sound wave grating period variation across the illuminated area on the acousto-optic modulator. Standoff detection capability of the AOM-based QCL setup was demonstrated for several solid materials.

  20. Simulation of the advective methane transport and AOM in Shenhu area, the Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Liu, L.; Wu, N.

    2012-04-01

    Anaerobic Oxidation of Methane (AOM) occurs in the transition zone between the presence of sulfate and methane. This reaction is an important process for methane and the global carbon cycle. Methane gas hydrates bearing sediments were recovered in Shenhu Area, the Northern South China Sea, and methane advective transport was detected in this area as well. A one dimension numerical simulation tool was implemented to study the AOM process combined with the advective methane transport in Shenhu Area according to the local drilling data and geochemical information. The modeled results suggest that local methane flux will be consumed in the sediment column via dissolution, sorption and AOM reaction. A portion of methane will enter water column and possibly atmosphere if the methane flux was one order of magnitude higher than current level. Furthermore, the calculated rates of AOM in Shenhu area range similar to that of gas hydrate mounds in Mexico Golf. However, AOM is ability to consume more methane than that in Golf of Mexico due to the lower permeable sediment associated with a deeper sulfate methane transition layer.

  1. Compact repetitively Q-switched Yb:YCa4O(BO3)3 laser with an acousto-optic modulator

    NASA Astrophysics Data System (ADS)

    Chen, Xiaowen; Xu, Honghao; Han, Wenjuan; Yi, Hongying; Yu, Haohai; Zhang, Huaijin; Liu, Junhai

    2015-07-01

    Repetitively Q-switched operation was achieved with a Yb:YCa4O(BO3)3 laser in a wide repetition rate range from 20 down to 0.1 kHz. An output power of 6.81 W at 20 kHz was generated with pulse duration of 42 ns; while operated at a low repetition rate of 0.1 kHz, the laser produced 0.53 W of output power with pulse width of 21 ns, the resulting pulse energy and peak power amounted respectively to 5.3 mJ and 252.4 kW.

  2. Effect of algogenic organic matter (AOM) and sodium chloride on Nannochloropsis salina flocculation efficiency.

    PubMed

    Garzon-Sanabria, Andrea J; Ramirez-Caballero, Silvia S; Moss, Francesca E P; Nikolov, Zivko L

    2013-09-01

    This study evaluates the effect of polymer molecular weight and charge density, algogenic organic matter (AOM), and salt concentration on harvesting efficiency of marine microalgae. Aluminum chloride (AlCl3), chitosan, and five synthetic cationic polymers of different molecular weights and charge density levels were used as flocculation agents. Polymer flocculation of marine microalgae was most efficient when using the highest charge density polymer (FO4990). The flocculant dosage irrespectively of the agent chemistry and charge density was affected by the amount of AOM secreted into the culture media. The presence of AOM increased the amount of required flocculant 7-fold when using synthetic cationic polymers; 10-fold with chitosan; and ~3-fold with AlCl3. Salt concentration of 5 or 35 g/L NaCl alone did not significantly affect removal efficiency, indicating that AOM were the main cause for the increased flocculant dosage requirement. The synthetic cationic polymer (FO4990) was the least expensive flocculation agent. PMID:23796606

  3. Improving transverse resolution of confocal microscopy through spatiotemporal modulation

    NASA Astrophysics Data System (ADS)

    Wang, Baokai; Zou, Limin; Zhang, Su; Tan, Jiubin

    2015-11-01

    A new method is proposed in this paper to improve transverse resolution of a confocal microscope. By setting up the model of a confocal microscope system through spatiotemporal modulation with moving gratings or acousto-optical modulation without defocus distance under coherent light illumination and deducing two-dimensional coherent image formula and transfer function, simulation tests are run with or without spatiotemporal modulation to prove the effectiveness of the proposed method. Simulation results indicate the proposed method can be used to improve the transverse resolution of a confocal microscope system.

  4. Characterizing algogenic organic matter (AOM) and evaluating associated NF membrane fouling.

    PubMed

    Her, Namguk; Amy, Gary; Park, Hyoung-Ryun; Song, Myoungsuk

    2004-03-01

    Occasional algal blooms, comprised of blue-green algae and/or green algae, cause significant challenges in drinking water treatment due to the release of algogenic organic matter (AOM) into water extracellularly and, upon cell lysis, intracellularly. AOM has been extracted from blue-green algae (cyanobacteria) by various means and analyzed by UV absorbance scanning, HPSEC-UV-fluorescence-DOC, UV absorbance ratio index (URI), FTIR, and fluorescence excitation emission matrix (EEM). AOM extracted in water as a solvent exhibited a high hydrophilic fraction (57.3%) with a low SUVA (1.0 L/m-mg). The molecular weight (MW) distribution showed a significant heterogeneity (high value of polydispersivity) and high protein content (as indicated by specific fluorescence). Significant amounts of proteinaceous components such as mycosporine-like amino acids (MAAs, UV-screening components) and phycobilins (light-harvesting pigment) were detected by UV/visible absorption. The presence of proteins was confirmed by FTIR (at 1661 and 1552 cm(-1)), EEM spectra (EX:278-282 nm and EM:304-353 nm), and high URI values (3.1-6.0). A bench-scale cross-flow unit, employing a flat-sheet membrane specimen, was used to examine nanofiltration (NF) membrane fouling and removal of natural organic matter (NOM) derived from different blends of Suwannee River humic acid (SRHA) and AOM: SRHA 10 mgC/L, AOM 3mg C/L + SRHA 7 mgC/L, AOM 7 mgC/L + SRHA 3 mgC/L, and AOM 10 mgC/L. The study focused mainly on the effects of two different sources of organic matter on NF (NF 200) membrane fouling under otherwise similar conditions. Flux decline and organic matter rejection as a function of delivered DOC (cumulative mass of feed DOC per unit area) showed significantly different results depending on the organic matter composition of samples even though the test conditions were the same (organic matter concentration, pH, temperature, inorganic salt composition and concentration, and recovery). A higher flux decline

  5. Broadband optical modulators based on graphene supercapacitors.

    PubMed

    Polat, Emre O; Kocabas, Coskun

    2013-01-01

    Optical modulators are commonly used in communication and information technology to control intensity, phase, or polarization of light. Electro-optic, electroabsorption, and acousto-optic modulators based on semiconductors and compound semiconductors have been used to control the intensity of light. Because of gate tunable optical properties, graphene introduces new potentials for optical modulators. The operation wavelength of graphene-based modulators, however, is limited to infrared wavelengths due to inefficient gating schemes. Here, we report a broadband optical modulator based on graphene supercapacitors formed by graphene electrodes and electrolyte medium. The transparent supercapacitor structure allows us to modulate optical transmission over a broad range of wavelengths from 450 nm to 2 μm under ambient conditions. We also provide various device geometries including multilayer graphene electrodes and reflection type device geometries that provide modulation of 35%. The graphene supercapacitor structure together with the high-modulation efficiency can enable various active devices ranging from plasmonics to optoelectronics. PMID:24215484

  6. Flavonoids Extracted from Licorice Prevents Colitis-Associated Carcinogenesis in AOM/DSS Mouse Model.

    PubMed

    Huo, Xiaowei; Liu, Dongyu; Gao, Li; Li, Liyong; Cao, Li

    2016-01-01

    Inflammatory bowel disease (IBD) is generally considered as a major risk factor in the progression of colitis-associated carcinogenesis (CAC). Thus, it is well accepted that ameliorating inflammation creates a potential to achieve an inhibitory effect on CAC. Licorice flavonoids (LFs) possess strong anti-inflammatory activity, making it possible to investigate its pharmacologic role in suppressing CAC. The purpose of the present study was to evaluate the anti-tumor potential of LFs, and further explore the underlying mechanisms. Firstly, an azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced mouse model was established and administered with or without LFs for 10 weeks, and then the severity of CAC was examined macroscopically and histologically. Subsequently, the effects of LFs on expression of proteins associated with apoptosis and proliferation, levels of inflammatory cytokine, expression of phosphorylated-Janus kinases 2 (p-Jak2) and phosphorylated-signal transducer and activator of transcription 3 (p-Stat3), and activation of nuclear factor-κB (NFκB) and P53 were assessed. We found that LFs could significantly reduce tumorigenesis induced by AOM/DSS. Further study revealed that LFs treatment substantially reduced activation of NFκB and P53, and subsequently suppressed production of inflammatory cytokines and phosphorylation of Jak2 and Stat3 in AOM/DSS-induced mice. Taken together, LFs treatment alleviated AOM/DSS induced CAC via P53 and NFκB/IL-6/Jak2/Stat3 pathways, highlighting the potential of LFs in preventing CAC. PMID:27563884

  7. High-power PPMgLN-based optical parametric oscillator pumped by a linearly polarized, semi-fiber-coupled acousto-optic Q-switched fiber master oscillator power amplifier.

    PubMed

    Chen, Tao; Jiang, Peipei; Yang, Dingzhong; Hu, Chengzhi; Wu, Bo; Shen, Yonghang

    2013-09-01

    We have experimentally demonstrated a periodically poled magnesium-oxide-doped lithium niobate (PPMgLN)-based, fiber-laser-pumped optical parametric oscillator (OPO) generating idler wavelength of 3.82 μm. The pump fiber laser was constructed with a linearly polarized, semi-fiber-coupled acousto-optic Q-switched fiber oscillator and a polarization-maintaining fiber amplifier with pulse duration of 190 ns at the highest output power. The OPO was specifically configured in single-pass, singly resonant linear cavity structure to avoid the damage risk of the pump fiber laser, which is always a serious issue in the fiber-laser-pumped, double-pass, singly oscillating structured OPOs. Under the highest pump power of 25 W, an idler average output power of 3.27 W with one-hour peak-to-peak instability of 5.2% was obtained. The measured M2 factors were 1.98 and 1.44 for horizontal and vertical axis, respectively. The high power stability and good beam quality demonstrated the suitability of such technology for practical application. PMID:24085093

  8. A process to control light in a micro resonator through a coupling modulation by surface acoustic waves

    PubMed Central

    Fan, Guofang; Li, Yuan; Hu, Chunguang; Lei, Lihua; Guo, Yanchuan

    2016-01-01

    A novel process to control light through the coupling modulation by surface acoustic wave (SAW) is presented in an optical micro resonator. An optical waveguide modulator of a racetrack resonator on silicon-on-insulator (SOI) technology is took as an example to explore the mechanism. A finite-difference time-domain (FDTD) is developed to simulate the acousto-optical (AO) modulator using the mechanism. An analytical method is presented to verify our proposal. The results show that the process can work well as an optical modulator by SAW. PMID:27485470

  9. A process to control light in a micro resonator through a coupling modulation by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Fan, Guofang; Li, Yuan; Hu, Chunguang; Lei, Lihua; Guo, Yanchuan

    2016-08-01

    A novel process to control light through the coupling modulation by surface acoustic wave (SAW) is presented in an optical micro resonator. An optical waveguide modulator of a racetrack resonator on silicon-on-insulator (SOI) technology is took as an example to explore the mechanism. A finite-difference time-domain (FDTD) is developed to simulate the acousto-optical (AO) modulator using the mechanism. An analytical method is presented to verify our proposal. The results show that the process can work well as an optical modulator by SAW.

  10. A process to control light in a micro resonator through a coupling modulation by surface acoustic waves.

    PubMed

    Fan, Guofang; Li, Yuan; Hu, Chunguang; Lei, Lihua; Guo, Yanchuan

    2016-01-01

    A novel process to control light through the coupling modulation by surface acoustic wave (SAW) is presented in an optical micro resonator. An optical waveguide modulator of a racetrack resonator on silicon-on-insulator (SOI) technology is took as an example to explore the mechanism. A finite-difference time-domain (FDTD) is developed to simulate the acousto-optical (AO) modulator using the mechanism. An analytical method is presented to verify our proposal. The results show that the process can work well as an optical modulator by SAW. PMID:27485470

  11. Optical modulators with 2D layered materials

    NASA Astrophysics Data System (ADS)

    Sun, Zhipei; Martinez, Amos; Wang, Feng

    2016-04-01

    Light modulation is an essential operation in photonics and optoelectronics. With existing and emerging technologies increasingly demanding compact, efficient, fast and broadband optical modulators, high-performance light modulation solutions are becoming indispensable. The recent realization that 2D layered materials could modulate light with superior performance has prompted intense research and significant advances, paving the way for realistic applications. In this Review, we cover the state of the art of optical modulators based on 2D materials, including graphene, transition metal dichalcogenides and black phosphorus. We discuss recent advances employing hybrid structures, such as 2D heterostructures, plasmonic structures, and silicon and fibre integrated structures. We also take a look at the future perspectives and discuss the potential of yet relatively unexplored mechanisms, such as magneto-optic and acousto-optic modulation.

  12. Evidence on Anaerobic Methane Oxidation (AOM) in a boreal cultivated peatland with natural and added electron acceptors

    NASA Astrophysics Data System (ADS)

    Dorodnikov, Maxim; Silvennoinen, Hanna; Martikainen, Pertti; Dörsch, Peter

    2015-04-01

    Anaerobic oxidation of methane (AOM) is a process of methane (CH4) consumption under anoxic conditions driven by microorganisms, which oxidize CH4 with various alternate electron acceptors (AEA): sulfate, nitrate, nitrite, metals-(Fe, Mn, Cu), organic compounds. AOM is common in marine ecosystems, where microbial sulfate reduction (SR) consumes most of the CH4 produced in sediments. Despite the global significance of AOM, the exact mechanisms and relevance of the process in terrestrial ecosystems are almost unknown. In the current study the occurrence of AOM was tested for two organic soil horizons (30 and 40 cm depth) and one mineral sub-soil (sand, 50 cm depth) of a cultivated boreal peatland (Linnansuo, Eastern Finland, energy crop Phalaris arundinacea - reed canarygrass) under controlled conditions with the addition of 13C-labeled CH4 and two common AEAs - SO4-2 and Fe+3. Concentrations of CH4, CO2 and O2 were continuously measured during 10 days of incubation and CO2 was sampled periodically under anaerobic conditions for stable 13C analysis. Oxygen dynamics revealed negligible O2 contamination during incubation and its trace amounts (0.05-0.8% from the atmospheric) were accounted in the net CH4 uptake. Application of 13C-enriched CH4 (4.9 atom%) allowed to track the label in CO2 as the end-product of AOM. The highest 13CO2 enrichment (up to 60‰) was observed in mineral sub-soil, however AOM was quantitatively more pronounced in the upper 30 cm horizon (2.1 vs. 0.2 μg CO2 g soil DW-1 in the 50 cm sub-soil). The highest AOM rate of 8.9 ng CO2 g soil DW-1 h-1 was estimated for the control treatment where no AEAs were added indicating sufficient amount of naturally available AEAs, likely organic compounds. This rate was 50 times more intensive (on the C basis) than the CH4 production potential of the same soil. In contrast, external AEAs decreased AOM rates but added Fe+3 stimulated decomposition of native SOM (as seen from the most depleted 13CO2 signatures

  13. Panax notoginseng attenuates experimental colitis in AOM/DSS mouse model

    PubMed Central

    Wen, Xiao-Dong; Wang, Chong-Zhi; Yu, Chunhao; Zhao, Lei; Zhang, Zhiyu; Matin, Adiba; Wang, Yunwei; Li, Ping; Xiao, Shu-Yuan; Du, Wei; He, Tong-Chuan; Yuan, Chun-Su

    2013-01-01

    Patients suffering from inflammatory bowel disease are at a high risk of developing colorectal cancer. To assess the anti-cancer potential of botanicals, in this study, we evaluated the effects of Panax notoginseng on azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colitis. One week after A/J mice received AOM, the animals received DSS for 8 days, or were supplemented with P. notoginseng extract, at 30 or 90 mg/kg. DSS-induced colitis was scored with the disease activity index (DAI). The severity of the inflammatory lesions was evaluated by a colon tissue histological assessment. The expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were also explored. We observed that the effects of P. notoginseng on the reduction of colon inflammation, expressed in DAI score, were in a dose-related manner (P < 0.01). P. notoginseng inhibited the reduction of the colon length and the loss of bodyweight in dose-related manner (all P < 0.05). The histological assessment of the colitis and inflammatory related immunohistochemical data also supported the pharmacological observations. Our data suggest that P. notoginseng is a promising candidate in preventing and treating colitis and inflammation-associated colon carcinogenesis. PMID:24142591

  14. Dual-mode single-crystal photoelastic modulator and possible applications.

    PubMed

    Petkovsek, Rok; Bammer, Ferdinand; Schuöcker, Dieter; Mozina, Janez

    2009-03-01

    A new type of acousto-optic device based on a LiTaO(3) crystal is presented. A harmonic voltage with a proper frequency applied to the piezoelectric LiTaO(3) crystal generates mechanical oscillations in the material. Due to photoelasticity, an artificial modulated birefringence is induced by this oscillation. By using a properly adjusted polarizer and analyzer, the transmission of trough-going polarized light can be modulated. By simultaneous excitation of two modes, an advanced optical response can be achieved. For the applications presented here, the first shear eigenmode must have exactly three times the frequency of the first longitudinal eigenmode. PMID:19252621

  15. Anaerobic oxidation of methane (AOM) in marine sediments from the Skagerrak (Denmark): II. Reaction-transport modeling

    NASA Astrophysics Data System (ADS)

    Dale, A. W.; Regnier, P.; Knab, N. J.; Jørgensen, B. B.; Van Cappellen, P.

    2008-06-01

    A steady-state reaction-transport model is applied to sediments retrieved by gravity core from two stations (S10 and S13) in the Skagerrak to determine the main kinetic and thermodynamic controls on anaerobic oxidation of methane (AOM). The model considers an extended biomass-implicit reaction network for organic carbon degradation, which includes extracellular hydrolysis of macromolecular organic matter, fermentation, sulfate reduction, methanogenesis, AOM, acetogenesis and acetotrophy. Catabolic reaction rates are determined using a modified Monod rate expression that explicitly accounts for limitation by the in situ catabolic energy yields. The fraction of total sulfate reduction due to AOM in the sulfate-methane transition zone (SMTZ) at each site is calculated. The model provides an explanation for the methane tailing phenomenon which is observed here and in other marine sediments, whereby methane diffuses up from the SMTZ to the top of the core without being consumed. The tailing is due to bioenergetic limitation of AOM in the sulfate reduction zone, because the methane concentration is too low to engender favorable thermodynamic drive. AOM is also bioenergetically inhibited below the SMTZ at both sites because of high hydrogen concentrations (∼3-6 nM). The model results imply there is no straightforward relationship between pore water concentrations and the minimum catabolic energy needed to support life because of the highly coupled nature of the reaction network. Best model fits are obtained with a minimum energy for AOM of ∼11 kJ mol-1, which is within the range reported in the literature for anaerobic processes.

  16. Dietary cholesterol promotes AOM-induced colorectal cancer through activating the NLRP3 inflammasome.

    PubMed

    Du, Qianming; Wang, Qing; Fan, Huimin; Wang, Jianing; Liu, Xiuting; Wang, Hong; Wang, Yajing; Hu, Rong

    2016-04-01

    Prolonged ingestion of a cholesterol-enriched diet induces chronic, auto-inflammatory responses resulting in significant health problems including colorectal cancer. Inflammasomes are thought to mediate intestinal homeostasis, and their dysregulation contributes to inflammatory bowel diseases and colitis-associated cancer (CAC). However, in vitro and in vivo information regarding the inflammation-inducing and tumor-promoting effect of cholesterol is lacking. Here we show that the cholesterol promoted colon carcinogenesis in azoxymethane (AOM)-treated mice through activating the NLRP3 inflammasome. High cholesterol diet (HCD) significantly increased inflammatory responses and tumor burden. Cholesterol crystals, detected in the colon of mice fed with HCD, also promoted NLRP3 inflammasome activation in macrophages, as indicated by elevated expression of cleaved caspase-1, formation of NLRP3-ASC-caspase-1 complex assembly, and higher IL-1β secretion. Importantly, cholesterol was found to inhibit the activity of AMPKα in macrophages, leading to a significant production of mitochondrial ROS, which in turn activated the NLRP3 inflammasome. Moreover, crystal uptake and cathepsin B accounted for cholesterol crystal-induced inactivation of AMPKα. Finally, HCD-induced increase in IL-1β secretion, macrophage infiltration and tumor burden was diminished by the deletion of NLRP3 in AOM-treated mice. Taken together, our findings demonstrate that the pro-inflammatory and cancer-promoting effects of HCD are mediated by the activation of NLRP3 inflammasome. Our study extended our knowledge on how dietary choices can influence processes involved in chronic inflammatory disorders and colorectal cancer. PMID:26921636

  17. Ultra stable carbon fiber high power CO2 laser with high quality laser beam and AOM implementation

    NASA Astrophysics Data System (ADS)

    Bohrer, Markus

    2015-03-01

    High security printing as well as ultra high precision engraving need laser resonators with very stable laser beams (600 - 800W) especially in combination with AOMs. Based upon a unique carbon fiber structure - stable within the sub-micrometer range - a new resonator has been developed, accompanied by most recent thermo-mechanical FEM calculations. The resulting beam is evaluated on an automated optical bench allowing to optimize the complete beam path with collimators and AOM. Synchronous on-line evaluation with PyroCams and thus knowledge about how to minimize distortions within the nonlinear elements is presented in this paper.

  18. Numerical and experimental analysis of the modulation of fiber Bragg gratings by low-frequency complex acoustic waves

    NASA Astrophysics Data System (ADS)

    Silva, Ricardo E.; Franco, Marcos A. R.; Neves, Paulo T.; Bartelt, Hartmut; Pohl, Alexandre A. P.

    2016-07-01

    The acoustically modulated bandwidth of fiber Bragg gratings is simulated and experimentally demonstrated. Finite element and transfer matrix methods are used to investigate a superposition of flexural and longitudinal acoustic waves and the induced complex strain in the grating, for the first time. The results show that the longitudinal strain is suitable to generate a bandwidth-voltage response. The modeling is useful for the design and characterization of acousto-optic modulators, which is attractive for the fast control of several photonic devices.

  19. Continuous-wave phase-matched molecular optical modulator

    PubMed Central

    Zaitsu, Shin-ichi; Izaki, Hirotomo; Tsuchiya, Takao; Imasaka, Totaro

    2016-01-01

    In optical modulation, the highest available modulation rate is basically limited to the GHz frequency range at best. This is because optical modulation is often performed using electro-optic or acousto-optic effects that require application of an external signal to solid-state nonlinear optical materials. Here we describe optical modulation of continuous-wave radiation at frequencies exceeding 10 THz based on ultrafast variation of molecule polarizability arising from coherent molecular motion. The optical modulation efficiency is extensively enhanced by fulfilling phase-matching conditions with the help of dispersion control of the optical cavity, generating sidebands with a highest ratio of 7.3 × 10−3. These results will pave the way for development of versatile optical modulation-based techniques in a wide range of research fields in optical sciences, such as mode-locked lasers operating in the THz range. PMID:26887500

  20. The AOM/DSS murine model for the study of colon carcinogenesis: From pathways to diagnosis and therapy studies

    PubMed Central

    Robertis, Mariangela De; Massi, Emanuela; Poeta, Maria Luana; Carotti, Simone; Morini, Sergio; Cecchetelli, Loredana; Signori, Emanuela; Fazio, Vito Michele

    2011-01-01

    Colorectal cancer (CRC) is a major health problem in industrialized countries. Although inflammation-linked carcinogenesis is a well accepted concept and is often observed within the gastrointestinal tract, the underlying mechanisms remain to be elucidated. Inflammation can indeed provide initiating and promoting stimuli and mediators, generating a tumour-prone microenvironment. Many murine models of sporadic and inflammation-related colon carcinogenesis have been developed in the last decade, including chemically induced CRC models, genetically engineered mouse models, and xenoplants. Among the chemically induced CRC models, the combination of a single hit of azoxymethane (AOM) with 1 week exposure to the inflammatory agent dextran sodium sulphate (DSS) in rodents has proven to dramatically shorten the latency time for induction of CRC and to rapidly recapitulate the aberrant crypt foci–adenoma–carcinoma sequence that occurs in human CRC. Because of its high reproducibility and potency, as well as the simple and affordable mode of application, the AOM/DSS has become an outstanding model for studying colon carcinogenesis and a powerful platform for chemopreventive intervention studies. In this article we highlight the histopathological and molecular features and describe the principal genetic and epigenetic alterations and inflammatory pathways involved in carcinogenesis in AOM/DSS–treated mice; we also present a general overview of recent experimental applications and preclinical testing of novel therapeutics in the AOM/DSS model. PMID:21483655

  1. Acousto-Optical/Electronic Processor For SAR

    NASA Technical Reports Server (NTRS)

    Bicknell, T. J.; Farr, W. H.

    1992-01-01

    Lightweight, compact, low-power apparatus processes synthetic-aperture-radar (SAR) returns in real time, providing imagery aboard moving aircraft or spacecraft platform. Processor includes optical and electronic subsystems that, together, resolve range and azimuth coordinates of radar targets by combination of spatial and temporal integrations.

  2. Multiple acousto-optic q-switch

    DOEpatents

    Deason, Vance A.

    1993-01-01

    An improved dynamic moire interferometer comprised of a lasing medium providing a plurality of beams of coherent light, a multiple q-switch producing multiple trains of 100,000 or more pulses per second, a combining means collimating multiple trains of pulses into substantially a single train and directing beams to specimen gratings affixed to a test material, and a controller, triggering and sequencing the emission of the pulses with the occurrence and recording of a dynamic loading event.

  3. Multiple acousto-optic q-switch

    DOEpatents

    Deason, Vance A.

    1993-12-07

    An improved dynamic moire interferometer comprised of a lasing medium providing a plurality of beams of coherent light, a multiple q-switch producing multiple trains of 100,000 or more pulses per second, a combining means collimating multiple trains of pulses into substantially a single train and directing beams to specimen gratings affixed to a test material, and a controller, triggering and sequencing the emission of the pulses with the occurrence and recording of a dynamic loading event.

  4. Depth selective acousto-optic flow measurement

    PubMed Central

    Tsalach, Adi; Schiffer, Zeev; Ratner, Eliahu; Breskin, Ilan; Zeitak, Reuven; Shechter, Revital; Balberg, Michal

    2015-01-01

    Optical based methods for non-invasive measurement of regional blood flow tend to incorrectly assess cerebral blood flow, due to contribution of extra-cerebral tissues to the obtained signal. We demonstrate that spectral analysis of phase-coded light signals, tagged by specific ultrasound patterns, enables differentiation of flow patterns at different depths. Validation of the model is conducted by Monte Carlo simulation. In-vitro experiments demonstrate good agreement with the simulations' results and provide a solid validation to depth discrimination ability. These results suggest that signal contamination originating from extra-cerebral tissue may be eliminated using spectral analysis of ultrasonically tagged light. PMID:26713201

  5. Frequency modulation and demodulation of a 10.6-micron CO2 laser

    NASA Astrophysics Data System (ADS)

    Yasuoka, Y.; Takahashi, T.; Gustafson, T. K.

    1980-01-01

    Frequency modulation and demodulation in optical communication is done using the 10.6-micron CO2 laser beam as a carrier. A Ge-LiNbO3 acousto-optic device and W-Ni point-contact diode are used as a modulator and a detector, respectively. The frequency of the carrier shifts by f sub zero by driving the modulator with the signal of f sub zero. By using the nonreflected laser beam as a local oscillator, the beat note when the transducer was driven by the signal from the sweep signal generator is obtained at the receiving station. Present experimental observations have demonstrated this, using the subcarrier of 38 MHz and the signal of 1 MHz as the driving frequencies of the modulator.

  6. Deflecting light into resonant cavities for spectroscopy

    DOEpatents

    Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.

    1998-01-01

    Light is coupled into a cavity ring down spectroscopy (CRDS) resonant cavity using an acousto-optic modulator. The AOM allows in-coupling efficiencies in excess of 40%, which is two to three orders of magnitude higher than in conventional systems using a cavity mirror for in-coupling. The AOM shutoff time is shorter than the roundtrip time of the cavity. The higher light intensities lead to a reduction in shot noise, and allow the use of relatively insensitive but fast-responding detectors such as photovoltaic detectors. Other deflection devices such as electro-optic modulators or elements used in conventional Q-switching may be used instead of the AOM. The method is particularly useful in the mid-infrared, far-infrared, and ultraviolet wavelength ranges, for which moderately reflecting input mirrors are not widely available.

  7. Deflecting light into resonant cavities for spectroscopy

    DOEpatents

    Zare, R.N.; Martin, J.; Paldus, B.A.

    1998-09-29

    Light is coupled into a cavity ring down spectroscopy (CRDS) resonant cavity using an acousto-optic modulator. The AOM allows in-coupling efficiencies in excess of 40%, which is two to three orders of magnitude higher than in conventional systems using a cavity mirror for in-coupling. The AOM shutoff time is shorter than the roundtrip time of the cavity. The higher light intensities lead to a reduction in shot noise, and allow the use of relatively insensitive but fast-responding detectors such as photovoltaic detectors. Other deflection devices such as electro-optic modulators or elements used in conventional Q-switching may be used instead of the AOM. The method is particularly useful in the mid-infrared, far-infrared, and ultraviolet wavelength ranges, for which moderately reflecting input mirrors are not widely available. 5 figs.

  8. Novel intercore-cladding lithium niobate thin film coated MOEMS fiber sensor/modulator

    NASA Technical Reports Server (NTRS)

    Jamlson, Tracee L.; Konreich, Phillip; Yu, Chung

    2005-01-01

    A MOEMS fiber modulator/sensor is fabricated by depositing a lithium niobate sol-gel thin film between the core and cladding of a fiber preform. The preform is then drawn into 125-micron fibers. Such a MOEMS modulator design is expected to enhance existing lithium niobate undersea acousto-optic sound wave detectors. In our proposed version, the lithium niobate thin film alters the ordinary silica core/cladding boundary conditions such that, when a stress or strain is applied to the fiber, the core light confinement factor changes, leading to modulation of fiber light transmission. Test results of the lithium niobate embedded fiber with a 1550-nm, 4-mW laser source revealed a reduction in light transmission with applied tension. As a comparison, using the same laser source, an ordinary silica core/cladding fiber did not exhibit any reduction in transmitted light when the same strain was applied. Further experimental work and theoretical analysis is ongoing.

  9. Two-Phonon Absorption

    ERIC Educational Resources Information Center

    Hamilton, M. W.

    2007-01-01

    A nonlinear aspect of the acousto-optic interaction that is analogous to multi-photon absorption is discussed. An experiment is described in which the second-order acousto-optically scattered intensity is measured and found to scale with the square of the acoustic intensity. This experiment using a commercially available acousto-optic modulator is…

  10. Lidar-radar velocimetry using a pulse-to-pulse coherent rf-modulated Q-switched laser.

    PubMed

    Vallet, M; Barreaux, J; Romanelli, M; Pillet, G; Thévenin, J; Wang, L; Brunel, M

    2013-08-01

    An rf-modulated pulse train from a passively Q-switched Nd:YAG laser has been generated using an extra-cavity acousto-optic modulator. The rf modulation reproduces the spectral quality of the local oscillator. It leads to a high pulse-to-pulse phase coherence, i.e., phase memory, over thousands of pulses. The potentialities of this transmitter for lidar-radar are demonstrated by performing Doppler velocimetry on indoor moving targets. The experimental results are in good agreement with a model based on elementary signal processing theory. In particular, we show experimentally and theoretically that lidar-radar is a promising technique that allows discrimination between translation and rotation movements. Being independent of the laser internal dynamics, this scheme can be applied to any Q-switched laser. PMID:23913058

  11. Asymmetric laser sideband generation with a tapered semiconductor amplifier

    NASA Astrophysics Data System (ADS)

    Yanakas, Michael; Lim, Michael

    2013-03-01

    We have constructed a free-space, frequency-shifted feedback amplifier using a tapered semiconductor gain element. The general layout of the system is similar to that described in Littler, et al., Opt. Comm. 88, 523 (1992). Traveling-wave feedback is demonstrated with the m = - 1 order of several different acousto-optic modulators driven at variable frequency. Asymmetric sideband production is observed in the rf spectrum of a fast photodiode and in the transmission of a scanning Fabry-Perot interferometer. The number of asymmetric modes is controlled with the AOM rf drive power and the seed laser optical power. Supported by NSF PHY-0613659

  12. Automated laser guidance of neuronal growth cones using a spatial light modulator.

    PubMed

    Carnegie, David J; Cizmár, Tomás; Baumgartl, Jörg; Gunn-Moore, Frank J; Dholakia, Kishan

    2009-11-01

    The growth cone of a developing neuron can be guided using a focused infra-red (IR) laser beam [1]. In previous setups this process has required a significant amount of user intervention to adjust continuously the laser beam to guide the growing neuron. Previously, a system using an acousto-optical deflector (AOD) has been developed to steer the beam [2]. However, to enhance the controllability of this system, here we demonstrate the use of a computer controlled spatial light modulator (SLM) to steer and manipulate the shape of a laser beam for use in guided neuronal growth. This new experimental setup paves the way to enable a comprehensive investigation into beam shaping effects on neuronal growth and we show neuronal growth initiated by a Bessel light mode. This is a robust platform to explore the biochemistry of this novel phenomenon. PMID:19705368

  13. Detection and analysis on versatile coding strategies of high frequency active Q-switched Nd:YVO4 laser for irradiance of different targets

    NASA Astrophysics Data System (ADS)

    El-Sherif, Ashraf F.; Talaat, Mahmoud

    2014-12-01

    We report an active Q-switching with different coded schemes generated in the high power diode end pumped Nd:YVO4 laser (DEPSS) using two different techniques of special combination of optical choppers and acousto-optic modulator (AOM) at higher repetition rates of 100 kHz for the first time to the best of our knowledge in any practical laser target designation (LTD) systems. The highest peak power of 95.4 kW with the lowest pulse repetition frequency of 222 Hz and pulse width of 46 ns at FWHM with the pulse-to-pulse stability of ~95% was measured at certain regime of operation. Special modulation and coding of high stable, high peak power Nd:YVO4 laser pulses at 1064 nm using the combination of different optical chopper blades were achieved. A high peak power of more than 4.84 kW with the shortest pulse width of 25 ns at FWHM has been obtained using an acousto-optic modulator (AOM) as an active Q-switched. The pulse-to-pulse stability was measured and improved to be ~97% at high repetition rate ranges from 10 kHz to 100 kHz. The correlation between the coded laser irradiation (transmitted) and the scattered (received) laser signals for three different targets materials of sand, wood and metal using this laser designation system are examined and discussed.

  14. Fibre laser component technology for 2-micron laser systems

    NASA Astrophysics Data System (ADS)

    Stevens, G.; Robertson, A.

    2014-05-01

    We report on recent developments in fibre laser component technology for use in 2-micron laser systems. A range of `building block' components has been built to allow novel fibre laser architectures that exploit the advantages of fibre lasers based on Thulium and Holmium active fibres. Fibre lasers operating around 2-microns are becoming widely used in an increasing number of applications, which is driving the need for components that can operate reliably at high powers and also integrate easily with other components. To that end, we have designed and built a range of fused fibre, acousto-optic and magneto-optic devices that can be readily integrated into a range of novel fibre laser systems. Research has been carried out into improving fused fibre technology for components operating at 2um wavelengths. Side-coupled feed through combiners have been developed with signal losses as low as 0.02dB and kilowatt level end-coupled pump couplers. Alongside this a range of taps, splitters and WDMs have been developed which allows for the implementation of a variety of laser architectures. Optical isolators based on new Faraday materials have been developed, providing over 30dB isolation, low insertion loss and 30W power handling in a fibre-in, fibre-out version. New cell designs and materials for Acousto-Optic devices have been researched leading to the development of fibre-coupled Acousto-Optic Modulators (AOM) and allows for the realisation of all fibre Thulium and Holmium Q-switched and pulsed fibre lasers. Novel Acousto-Optic Tunable Filters (AOTF) designs have been realised to produce narrow resolution AOTFs and zero-shift AOTFs.

  15. Method for independent and continuous tuning of N lasers phase-locked to the same frequency comb

    NASA Astrophysics Data System (ADS)

    Gunton, Will; Semczuk, Mariusz; Madison, Kirk W.

    2015-09-01

    We present a method of phase-locking any number of continuous-wave lasers to an optical frequency comb (OFC) that enables independent frequency positioning and control of each laser while still maintaining lock to the OFC. The scheme employs an acousto-optic modulator (AOM) in a double pass configuration added to each laser before its light is compared by optical heterodyne with the comb. The only requirement is that the tuning bandwidth of the double pass AOM setup be larger than half the OFC repetition rate. We demonstrate this scheme and achieve an arbitrary frequency tuning precision, a tuning rate of 200~MHz/s and a readout precision at the 1~kHz level.

  16. An Acousto-Optical Sensor with High Angular Resolution

    PubMed Central

    Kaloshin, Gennady; Lukin, Igor

    2012-01-01

    The paper introduces a new laser interferometry-based sensor for diagnosis of random media by means of high accuracy angle measurements and describes the results of its development and testing. Theoretical calculations of the dependence of the range of the laser interferometer on laser beam parameters, device geometry, and atmospheric turbulence characteristics are reported. It is demonstrated that at moderate turbulence intensities corresponding to those observed most frequently in turbulent atmosphere at moderate latitudes and with low interference contrast values, the performance range of the laser interferometer-based device exceeds 5 km. PMID:22737034

  17. Acousto-optic filter for electronic laser tuning

    NASA Technical Reports Server (NTRS)

    Harris, S. E.

    1972-01-01

    Electronically tunable lithium niobate filter utilizes acoustic-optic diffraction for tuning laser to desired frequencies. Filter placed inside laser cavity diffracts incident optical signal of one polarization into orthogonal polarization by collinearly propagating acoustic beam to desired wavelength.

  18. Application of interferometry in analyzing gas flow in microchannels

    NASA Astrophysics Data System (ADS)

    Li, Yongli; Newport, David; Joseph, Shiju; Brandner, Juergen J.

    2011-11-01

    Interferometry is a noninvasive measurement and based on this technique, the measurement or visualization of changes in physical properties of transparent objects can be achieved by detecting the refractive index changes. Gas pressure and temperature can be related to their refractive index, so interferometry can be used for local measurement of changes of these properties along the channel. A Mach-Zehnder interferometer was built with a laser with a wavelength of 633 nm, a high speed camera and two acousto-optic modulators (AOMs). Due to small channel characteristic length and sometimes low gas pressure, the measurement could be much influenced by noise. The AOMs can introduce frequency shifts into the system by acousto-optic effect, which can avoid mechanical noise generally by translating piezoelectric mirrors. The channel sides with optical access are made from crystalline silica (Quartz) that does not show speckle effects and any laser absorbance. For initial tests, the local gas pressure drop distribution along microchannel is studied at room temperature. The research leading to these results has received funding from the European Community's Seventh Framework Programme (ITN - FP7/2007-2013) under grant agreement no. 215504.

  19. Investigation of the low-level modulated light action

    NASA Astrophysics Data System (ADS)

    Antonov, Sergei N.; Sotnikov, V. N.; Koreneva, L. G.

    1994-07-01

    Now there exists no clear complete knowledge about mechanisms and pathways by which low level laser bioactivation works. Modulated laser light action has been investigated two new ways: dynamical infrared thermography and computing image of living brain. These ways permit observation in real time laser action on peripheral blood flow, reflex reactions to functional probes, thermoregulation mechanisms as well as brain electrical activity changes of humans. We have designed a universal apparatus which produced all regimes of the output laser light. It has a built-in He-Ne laser with an acousto-optic modulator and an infrared GaAs laser. The device provided spatial combination of both the light beams and permitted us to irradiate an object both separately and simultaneously. This research shows that the most effective frequencies range from several to dozens of hertz. The duty factor and frequency scanning are also important. On the basis of these results in Russian clinics new treatment methods using modulated light are applied in practical neurology, gynecology, etc.

  20. Advances in modulation spectroscopy: State-of-art photoreflectance metrology

    NASA Astrophysics Data System (ADS)

    Murtagh, M. E.; Ward, S.; Nee, D.; Kelly, P. V.

    2006-10-01

    In this paper, technological advances of modulation spectroscopy are presented, exploiting the sensitivity, room-temperature resolution, as well as the rapid and non-contact (non-destructive) nature of laser-induced photoreflectance (PR). A novel method of asynchronous (switching) modulation is presented to overcome laser-induced non-PR background effects, which limit or even obscure the complex (phase) PR response. The solid-state, acousto-optic based method may even be employed for non-uniform samples, and moreover, exhibits evidence for improved signal-to-noise level. Also presented is a novel optical design in order to achieve multiple, independent and simultaneous spectral acquisition, including auto-calibration. Results are demonstrated for heavily doped n-type and p-type GaAs substrates, and also technologically important HBT device structures, with further applications also emphasised for HEMTs, LEDs, etc. The results demonstrate the importance and role of PR as a successful commercial metrology tool for existing state-of-art, as well as next generation semiconductor characterisation and statistical-process-control (SPC) equipment.

  1. Inhibitory Effects of Soy Protein Isolate on Intestional Carcinogenesis in Azoxymethane (AOM)-treated Sprague-Dawley Rats are Subsite-specific and Linked to Insulin/IGF Action

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our laboratories have reported inhibitory effects on colon carcinogenesis of soy protein isolate (SPI) in AOM-treated male rats. In the present study, we examined regional and hormonal aspects of the intestinal cancer-preventative actions of SPI. Pregnant Sprague-Dawley dams at gestation day 4 were ...

  2. Co-integration of a smart CMOS image sensor and a spatial light modulator for real-time optical phase modulation

    NASA Astrophysics Data System (ADS)

    Laforest, Timothé; Verdant, Arnaud; Dupret, Antoine; Gigan, Sylvain; Ramaz, François; Tessier, Gilles

    2014-03-01

    We present a CMOS light detector-actuator array, in which every pixel combines a spatial light modulator and a photodiode. It will be used in medical imaging based on acousto-optical coherence tomography with a digital holographic detection scheme. Our architecture is able to measure an interference pattern between a scattered beam transmitted through a scattering media and a reference beam. The array of 16 μm pixels pitch has a frame rate of several kfps, which makes this sensor compliant with the correlation time of light in biological tissues. In-pixel analog processing of the interference pattern allows controlling the polarization of a stacked light modulator and thus, to control the phase of the reflected beam. This reflected beam can then be focused on a region of interest, i.e. for therapy. The stacking of a photosensitive element with a spatial light modulator on the same chip brings a significant robustness over the state of the art such as perfect optical matching and reduced delay in controlling light.

  3. Tailoring ultrasonic beams with optoacoustic holography

    NASA Astrophysics Data System (ADS)

    Meyer, Alex; Gspan, Stefan J.; Bernet, Stefan; Ritsch-Marte, Monika

    2003-06-01

    A combination of laser-induced ultrasound generation and ultrasonic holography for spatial control of the generated ultrasonic pulse is presented. Ultrasound is produced by absorption of laser pulses at an absorbing layer in a water tank via the optoacoustic effect. In order to produce a defined ultrasonic frequency in the MHz range, the laser pulses are harmonically time-modulated using an acousto-optic modulator (AOM). Additionally, the laser intensity is spatially controlled. This is realized with a high resolution liquid crystal spatial light modulator (LCD). A computer generated pattern is displayed at the LCD and projected by the expanded laser beam to an absorptive layer in the water tank. As a result, the emitted ultrasonic wave emerges in a predetermined way, which is an acoustical analogue to the effect of a "diffractive optical element" in laser optics. The flexible method of optical ultrasound generation and diffractive steering promises new applications in medical and technical ultrasound diagnostics.

  4. Linearly polarized, dual wavelength frequency-modulated continuous-wave fiber laser for simultaneous coherent distance and speed measurements

    NASA Astrophysics Data System (ADS)

    Chen, Tao; Wu, Jun; Xu, Weiming; He, Zhiping; Qian, Liqun; Shu, Rong

    2016-07-01

    We have experimentally demonstrated a high power linearly polarized, dual wavelength frequency-modulated continuous-wave (FMCW) fiber laser with master-oscillator power-amplifier (MOPA) configuration, which is specially designed for simultaneous coherent distance and speed measurements. Two single longitudinal mode laser diodes working at 1550.12 and 1554.13 nm are employed as the seeds of the fiber MOPA. The wavelengths of the seeds are externally modulated by two acousto-optic frequency shifters (AOFSes) with a symmetrical sawtooth wave from 330–460 MHz in the frequency domain. The modulation periodicities for the two seeds are 26 and 26.3 μs, respectively, by which the distance ambiguity can be eliminated and therefore the detection range can be extended to a great extent. The seeds are then amplified independently to reduce their power differences during frequency modulation. After being coupled and boosted with three successive fiber amplifiers, an output power of 12.1 W is recorded from the FMCW laser with a power instability   <0.14% over 1.5 h. The measured PER and full divergence angle of the laser are  >18 dB and  <25 μrad, respectively, indicating its excellent performance for field measurements.

  5. Laser Metrology for an Optical-Path-Length Modulator

    NASA Technical Reports Server (NTRS)

    Gursel, Yekta

    2005-01-01

    Laser gauges have been developed to satisfy requirements specific to monitoring the amplitude of the motion of an optical-path-length modulator that is part of an astronomical interferometer. The modulator includes a corner-cube retroreflector driven by an electromagnetic actuator. During operation of the astronomical interferometer, the electromagnet is excited to produce linear reciprocating motion of the corner-cube retroreflector at an amplitude of 2 to 4 mm at a frequency of 250, 750, or 1,250 Hz. Attached to the corner-cube retroreflector is a small pick-off mirror. To suppress vibrations, a counterweight having a mass equal to that of the corner-cube retroreflector and pick-off mirror is mounted on another electromagnetic actuator that is excited in opposite phase. Each gauge is required to measure the amplitude of the motion of the pick-off mirror, assuming that the motions of the pick-off mirror and the corner-cube retroreflector are identical, so as to measure the amplitude of motion of the corner- cube retroreflector to within an error of the order of picometers at each excitation frequency. Each gauge is a polarization-insensitive heterodyne interferometer that includes matched collimators, beam separators, and photodiodes (see figure). The light needed for operation of the gauge comprises two pairs of laser beams, the beams in each pair being separated by a beat frequency of 80 kHz. The laser beams are generated by an apparatus, denoted the heterodyne plate, that includes stabilized helium-neon lasers, acousto-optical modulators, and associated optical and electronic subsystems. The laser beams are coupled from the heterodyne plate to the collimators via optical fibers.

  6. Investigation of a 10 MHz, non-steady state cavity for pulse energy enhancement of ultrafast fiber lasers

    NASA Astrophysics Data System (ADS)

    Breitkopf, Sven; Wunderlich, Stefano; Eidam, Tino; Shestaev, Evgeny; Gottschall, Thomas; Carstens, Henning; Holzberger, Simon; Pupeza, Ioachim; Limpert, Jens; Tünnermann, Andreas

    2016-03-01

    Here, we present a passive 30-m long enhancement cavity that supports a steady-state enhancement of 198, which is the highest enhancement that has ever been reached in such a long cavity. Furthermore, we demonstrate the extraction of a short burst with a total energy of 53.6 μJ employing an acousto-optic modulator (AOM) as a switching device. The cavity was seeded with pulses of 1.49 μJ energy at 10 MHz repetition rate. The individual output coupled pulses showed an energy enhancement of up to 8.5 while the whole burst contained the entire energy of 36 input pulses. In the last section theoretical considerations for the single pulse extraction are presented and briefly discussed.

  7. An actively mode-locked Ho: YAG solid laser pumped by a Tm: YLF laser

    NASA Astrophysics Data System (ADS)

    Yao, B. Q.; Cui, Z.; Wang, J.; Duan, X. M.; Dai, T. Y.; Du, Y. Q.; Yuan, J. H.; Liu, W.

    2015-02-01

    A continuous wave mode-locked (CWML) Ho: YAG laser based on an acousto-optic modulator (AOM) pumped by a 1.9 μm Tm: YLF laser is demonstrated. This is the first time a report on an active CWML Ho: YAG laser has been published. A maximum output power of 1.04 W at 2097.25 nm in the CWML regime is obtained at a pump power of 13.2 W, corresponding to a slope efficiency of 13.3%. The mode-locked pulse repetition frequency is 82.76 MHz and the single pulse energy is 12.57 nJ. The mode-locked pulse width is 102 ps measured through a no-background second harmonic autocorrelation with KTP as the nonlinear crystal. Furthermore, the M2 factor is calculated to be 1.146.

  8. Adaptable beam profiles from a dual-cavity Nd:YAG laser.

    PubMed

    Kim, D J; Mackenzie, J I; Kim, J W

    2016-04-15

    We report a technique to tailor a laser beam profile from a donut to quasi-top-hat intensity distribution, directly from the laser, simply achieved by simultaneous excitation and control of the relative contributions of the fundamental (TEM00) and first-order Laguerre-Gaussian (LG01) transverse modes. Exploiting a dual-cavity configuration with a single Nd:YAG gain element, adaptable continuous-wave laser beam profiles from the primary cavity could be obtained by varying the diffraction loss of an acousto-optic modulator in the secondary cavity. We investigate the resultant beam profiles as a function of pump power and the AOM diffraction loss, and discuss the prospects for tunable laser beams profiles. PMID:27082333

  9. 5kW High peak power, 0.2 mJ high pulse energy, linearly-polarized pulsed laser from a single all-fiber oscillator

    NASA Astrophysics Data System (ADS)

    Shi, Chen; Huang, Long; Wang, Xiaolin; Zhou, Pu

    2015-12-01

    We report a high peak power ytterbium-doped fiber laser that emitted linearly-polarized laser at 1064 nm. An intracavity polarization-maintaining (PM) acousto-optic modulator (AOM) was used as a Q-switch to generate pulsed laser output. The whole system was constructed with all-fiber structure. The power of the polarized laser reached 4.21 W and a polarization purity of greater than 97.6% under the repetition rate of 20 kHz. The pulse width was 37 ns, which implied a 5 kW peak power and 0.2 mJ pulse energy. It is the highest peak power output from a linearly-polarized, Q-switched fiber laser oscillator to the best of our knowledge.

  10. Fiber laser-microscope system for femtosecond photodisruption of biological samples

    PubMed Central

    Yavaş, Seydi; Erdogan, Mutlu; Gürel, Kutan; Ilday, F. Ömer; Eldeniz, Y. Burak; Tazebay, Uygar H.

    2012-01-01

    We report on the development of a ultrafast fiber laser-microscope system for femtosecond photodisruption of biological targets. A mode-locked Yb-fiber laser oscillator generates few-nJ pulses at 32.7 MHz repetition rate, amplified up to ∼125 nJ at 1030 nm. Following dechirping in a grating compressor, ∼240 fs-long pulses are delivered to the sample through a diffraction-limited microscope, which allows real-time imaging and control. The laser can generate arbitrary pulse patterns, formed by two acousto-optic modulators (AOM) controlled by a custom-developed field-programmable gate array (FPGA) controller. This capability opens the route to fine optimization of the ablation processes and management of thermal effects. Sample position, exposure time and imaging are all computerized. The capability of the system to perform femtosecond photodisruption is demonstrated through experiments on tissue and individual cells. PMID:22435105

  11. Ultrasound modulated light blood flow measurement using intensity autocorrelation function: a Monte-Carlo simulation

    NASA Astrophysics Data System (ADS)

    Tsalach, A.; Metzger, Y.; Breskin, I.; Zeitak, R.; Shechter, R.

    2014-03-01

    Development of techniques for continuous measurement of regional blood flow, and in particular cerebral blood flow (CBF), is essential for monitoring critical care patients. Recently, a novel technique, based on ultrasound modulation of light was developed for non-invasive, continuous CBF monitoring (termed ultrasound-tagged light (UTL or UT-NIRS)), and shown to correlate with readings of 133 Xe SPECT1 and laser Doppler2. Coherent light is introduced into the tissue concurrently with an Ultrasound (US) field. Displacement of scattering centers within the sampled volume induced by Brownian motion, blood flow and the US field affects the photons' temporal correlation. Hence, the temporal fluctuations of the obtained speckle pattern provide dynamic information about the blood flow. We developed a comprehensive simulation, combining the effects of Brownian motion, US and flow on the obtained speckle pattern. Photons trajectories within the tissue are generated using a Monte-Carlo based model. Then, the temporal changes in the optical path due to displacement of scattering centers are determined, and the corresponding interference pattern over time is derived. Finally, the light intensity autocorrelation function of a single speckle is calculated, from which the tissue decorrelation time is determined. The simulation's results are compared with in-vitro experiments, using a digital correlator, demonstrating decorrelation time prediction within the 95% confidence interval. This model may assist in the development of optical based methods for blood flow measurements and particularly, in methods using the acousto-optic effect.

  12. A flexible master oscillator for a pulse-burst laser system

    NASA Astrophysics Data System (ADS)

    Den Hartog, D. J.; Young, W. C.

    2015-12-01

    A new master oscillator is being installed in the pulse-burst laser system used for high-rep-rate Thomson scattering on the MST experiment. This new master oscillator will enable pulse repetition rates up to 1 MHz, with the ability to program a burst of pulses with arbitrary and varying time separation between each pulse. In addition, the energy of each master oscillator pulse can be adjusted to compensate for gain variations in the power amplifier section of the laser system. This flexibility is accomplished by chopping a CW laser source with a high-bandwidth acousto-optic modulator (AOM). The laser source is a Laser Quantum ventus 1064 diode-pumped solid-state laser with continuous output power variable from 100 to 500 mW. The 1064 nm, 2.7 mm diameter polarized beam is focused into the gallium phosphide crystal of a Brimrose AOM, which deflects the beam by approximately 60 mR when driven by the 400 MHz fixed frequency driver. Beam deflection is controlled by a simple digital input pulse, and is capable of producing deflected pulses of less than 20 ns width at repetition rates much greater than 1 MHz. These deflected pulses from the output of the AOM are collimated and propagated into the laser amplifier system, where they will be amplified to ~ 2 J/pulse and injected into the MST plasma.

  13. Comparisons of 2D IR measured spectral diffusion in rotating frames using pulse shaping and in the stationary frame using the standard method

    NASA Astrophysics Data System (ADS)

    Karthick Kumar, S. K.; Tamimi, A.; Fayer, M. D.

    2012-11-01

    Multidimensional visible spectroscopy using pulse shaping to produce pulses with stable controllable phases and delays has emerged as an elegant tool to acquire electronic spectra faster and with greatly reduced instrumental and data processing errors. Recent migration of this approach using acousto-optic modulator (AOM) pulse shaping to the mid-infrared region has proved useful for acquiring two dimensional infrared (2D IR) vibrational echo spectra. The measurement of spectral diffusion in 2D IR experiments hinges on obtaining accurate 2D line shapes. To date, pulse shaping 2D IR has not been used to study the time-dependent spectral diffusion of a vibrational chromophore. Here we compare the spectral diffusion data obtained from a standard non-collinear 2D IR spectrometer using delay lines to the data obtained from an AOM pulse shaper based 2D IR spectrometer. The pulse shaping experiments are performed in stationary, partially rotating, and fully rotating reference frames and are the first in the infrared to produce 2D spectra collected in a fully rotating frame using a phase controlled pulse sequence. Rotating frame experiments provide a dramatic reduction in the number of time points that must be measured to obtain a 2D IR spectrum, with the fully rotating frame giving the greatest reduction. Experiments were conducted on the transition metal carbonyl complex tricarbonylchloro(1,10-phenanthroline)rhenium(I) in chloroform. The time dependent data obtained from the different techniques and with different reference frames are shown to be in agreement.

  14. Analysis of a crossed Bragg-cell acousto optical spectrometer for SETI

    NASA Technical Reports Server (NTRS)

    Gulkis, S.

    1986-01-01

    The search for radio signals from extraterrestrial intelligent (SETI) beings requires the use of large instantaneous bandwidth (500 MHz) and high resolution (20 Hz) spectrometers. Digital systems with a high degree of modularity can be used to provide this capability, and this method has been widely discussed. Another technique for meeting the SETI requirement is to use a crossed Bragg-cell spectrometer as described by Psaltis and Casasent (1979). This technique makes use of the Folded Spectrum concept, introduced by Thomas (1966). The Folded Spectrum is a two-dimensional Fourier Transform of a raster scanned one-dimensional signal. It is directly related to the long one-dimensional spectrum of the original signal and is ideally suited for optical signal processing.

  15. Analysis of a crossed Bragg cell acousto-optical spectrometer for SETI

    NASA Technical Reports Server (NTRS)

    Gulkis, S.

    1989-01-01

    The search for radio signals from extraterrestrial intelligent beings (SETI) requires the use of large instantaneous bandwidth (500 MHz) and high resolution (20 Hz) spectrometers. Digital systems with a high degree of modularity can be used to provide this capability, and this method has been widely discussed. Another technique for meeting the SETI requirement is to use a crossed Bragg cell spectrometer as described by Psaltis and Casasent. This technique makes use of the Folded Spectrum concept, introduced by Thomas. The Folded Spectrum is a 2-D Fourier Transform of a raster scanned 1-D signal. It is directly related to the long 1-D spectrum of the original signal and is ideally suited for optical signal processing. The folded spectrum technique has received little attention to date, primarily because early systems made use of photographic film which are unsuitable for the real time data analysis and voluminous data requirements of SETI. An analysis of the crossed Bragg cell spectrometer is presented as a method to achieve the spectral processing requirements for SETI. Systematic noise contributions unique to the Bragg cell system will be discussed.

  16. Measurement of acousto-optic interaction in germanium in the far infrared

    SciTech Connect

    Duerr, W.; Schmidt, W.

    1985-10-01

    Acoustooptic interaction in a germanium Bragg cell, which was operated as an acoustic resonator, was measured at 119 microns relative to 10.6 microns. The figure of merit of the material was found to be approximately 20 percent higher in the far infrared. The performance of various acoustooptic materials in the far infrared is briefly discussed. 5 references.

  17. Acousto-optic signature analysis for inspection of the orbiter thermal protection tile bonds

    NASA Technical Reports Server (NTRS)

    Rodriguez, Julio G.; Tow, D. M.; Barna, B. A.

    1990-01-01

    The goal of this research is to develop a viable NDE technique for the inspection of orbiter thermal protection system (TPS) tile bonds. Phase 2, discussed here, concentrated on developing an empirical understanding of the bonded and unbonded vibration signatures of acreage tiles. Controlled experiments in the laboratory have provided useful information on the dynamic response of TPS tiles. It has been shown that several signatures are common to all the pedigree tiles. This degree of consistency in the tile-SIP (strain isolation pad) dynamic response proves that an unbond can be detected for a known tile and establish the basis for extending the analysis capability to arbitrary tiles for which there are no historical data. The field tests of the noncontacting laser acoustic sensor system, conducted at the Kennedy Space Center (KSC), investigated the vibrational environment of the Orbiter Processing Facility (OPF) and its effect on the measurement and analysis techniques being developed. The data collected showed that for orbiter locations, such as the body flap and elevon, the data analysis scheme, and/or the sensor, will require modification to accommodate the ambient motion. Several methods were identified for accomplishing this, and a solution is seen as readily achievable. It was established that the tile response was similar to that observed in the laboratory. Of most importance, however, is that the field environment will not affect the physics of the dynamic response that is related to bond condition. All of this information is fundamental to any future design and development of a prototype system.

  18. Acousto-optic signature analysis for inspection of the orbiter thermal protection tile bonds

    SciTech Connect

    Rodriguez, J.G.; Tow, D.M.; Barna, B.A.

    1989-01-01

    The goal of this research is to develop a viable, on contacting NDE technique for the inspection of orbiter thermal protection system (TPS) tile bonds. Phase 2, discussed here, concentrated on developing an empirical understanding of the b onded and unbonded vibration signatures of acreage tiles. Controlled experiments in the laboratory have provided useful information on the dynamic response of TPS tiles. It has been shown that several signatures are common to all the pedigree'' tiles. This degree of consistency in the tile-SIP (strain isolation pad) dynamic response proves that an unbond can be detected for a known tile and established the basis for extending the analysis capability to arbitrary tiles for which there are no historical data. The field tests of the noncontacting laser acoustic sensor system, conducted at Kennedy Space Center (KSC), investigated the vibrational environment of the Orbiter Processing Facility (OPF) and its effect on the measurement and analysis techniques being developed. The data collected showed that for orbiter locations, such as the body flap and elevon, the data analysis scheme, and/or the sensor, will require modification to accommodate the ambient motion. Several methods have been identified for accomplishing this, and a solution is seen as readily achievable. It was established that the tile response was similar to that observed in the laboratory. Of most importance, however, is that the field environment will not affect the physics of the dynamic response that is related to bond condition. All of this information is fundamental to any future design and development of a prototype system. 2 refs., 9 figs.

  19. Analysis of a crossed Bragg cell acousto-optical spectrometer for SETI.

    PubMed

    Gulkis, S

    1989-01-01

    The search for radio signals from extraterrestrial intelligent beings (SETI) requires the use of large instantaneous bandwidth (500 MHz) and high resolution (20 Hz) spectrometers. Digital systems with a high degree of modularity can be used to provide this capability, and this method has been widely discussed. Another technique for meeting the SETI requirement is to use a crossed Bragg cell spectrometer as described by Psaltis and Casasent. This technique makes use of the Folded Spectrum concept, introduced by Thomas. The Folded Spectrum is a 2-D Fourier Transform of a raster scanned 1-D signal. It is directly related to the long 1-D spectrum of the original signal and is ideally suited for optical signal processing. The folded spectrum technique has received little attention to date, primarily because early systems made use of photographic film which are unsuitable for the real time data analysis and voluminous data requirements of SETI. An analysis of the crossed Bragg cell spectrometer is presented as a method to achieve the spectral processing requirements for SETI. Systematic noise contributions unique to the Bragg cell system will be discussed. PMID:11537748

  20. Space Qualification Issues in Acousto-optic and Electro-optic Devices

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Taylor, Edward W.; Trivedi, Sudhir; Kutcher, Sue; Soos, Jolanta

    2007-01-01

    Satellite and space-based applications of photonic devices and systems require operational reliability in the harsh environment of space for extended periods of time. This in turn requires every component of the systems and their packaging to meet space qualifications. Acousto- and electro-optical devices form the major components of many current space based optical systems, which is the focus of this paper. The major space qualification issues are related to: mechanical stability, thermal effects and operation of the devices in the naturally occurring space radiation environment. This paper will discuss acousto- and electro-optic materials and devices with respect to their stability against mechanical vibrations, thermal cycling in operating and non-operating conditions and device responses to space ionizing and displacement radiation effects. Selection of suitable materials and packaging to meet space qualification criteria will also be discussed. Finally, a general roadmap for production and testing of acousto- and electro-optic devices will be discussed.

  1. Method of analysis of acousto-optic interaction using Kotelnikov-Shannon distribution on sample functions

    NASA Astrophysics Data System (ADS)

    Rysakov, Wladimir; Ston, Marian

    1995-10-01

    A new method of analysis of light interaction with phase lattices limited in space is offered. The method is based on expansion of fields in spectra on the Kotelnikov-Shannon sampling function. this base system of the functions does not have information redundancy and permits one to define directly the power-generating characteristics of a diffracting light, instead of its complex amplitudes. The scattering field appears quantized. The signal is defined simply by the sum of powers of elementary beams in the received aperture. The absence of redundant information about a phase rather simplifies the solution. The possibilities of the method are illustrated by examples of Bragg's diffraction on coherent sound, transition in scattering with decreased degree of coherency, transition in Raman-Nath regime at decreased thickness of the volume of interaction.

  2. A Flexible Master Oscillator for a Thomson Scattering Pulse-Burst Laser System

    NASA Astrophysics Data System (ADS)

    den Hartog, D. J.; Young, W. C.

    2015-11-01

    A new master oscillator will be installed in the pulse-burst laser system used for high-rep-rate Thomson scattering on the MST experiment. This new master oscillator will enable pulse repetition rates up to 1 MHz, with the ability to program a burst of pulses with arbitrary and varying time separation between each pulse. In addition, the energy of each master oscillator pulse can be adjusted to compensate for gain variations in the power amplifier section of the laser system. This flexibility is accomplished by chopping a CW laser source with a high-bandwidth acousto-optic modulator (AOM). The laser source is a 1064 nm diode-pumped solid-state laser with continuous output power variable from 100 to 500 mW. The 2 mm diameter polarized beam is focused into the gallium phosphide crystal of the AOM, which deflects the beam by approximately 60 mrad. Beam deflection is controlled by a simple digital input pulse, and is capable of producing laser pulses of less than 20 ns width at repetition rates much greater than 1 MHz. These pulses from the output of the AOM will be collimated and propagated into the laser amplifier system, where they will be amplified to ~ 2 J/pulse and injected into the MST plasma. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number DE-FC02-05ER54814, and by the National Science Foundation under Award Number PHY-0821899.

  3. Non-digestible fraction of beans (Phaseolus vulgaris L.) modulates signalling pathway genes at an early stage of colon cancer in Sprague-Dawley rats.

    PubMed

    Haydé, Vergara-Castañeda; Ramón, Guevara-González; Lorenzo, Guevara-Olvera; Dave, Oomah B; Rosalía, Reynoso-Camacho; Paul, Wiersma; Guadalupe, Loarca-Piña

    2012-08-01

    Colorectal cancer is one of the most common causes of morbidity and mortality in Western countries, the second cause of cancer mortality in the USA and a major public health problem in Mexico. A diet rich in legumes is directly related to the prevention of colon cancer, showing an inverse relationship with the development of colorectal adenomas in human subjects. The present study shows the results of molecular changes involved in the Tp53 pathway at an early stage in the distal colon tissue of azoxymethane (AOM)-induced colon cancer in rats evaluated by PCR array after exposure to diets containing the non-digestible fraction (NDF) of cooked bean (cultivar Bayo Madero). Significant differences were detected in seventy-two genes of the Tp53-mediated signalling pathway involved in apoptosis, cell-cycle regulation and arrest, inhibition of proliferation and inflammation, and DNA repair. Tp53, Gadd45a, Cdkn1a and Bax were highly expressed (9·3-, 18·3-, 5·5- and 3·5-fold, respectively) in the NDF+AOM group, whereas Cdc25c, Ccne2, E2f1 and Bcl2 were significantly suppressed ( - 9·2-, - 2·6-, - 18·4- and - 3·5-fold, respectively), among other genes, compared with the AOM group, suggesting that chemoprevention of aberrant crypt foci results from a combination of cell-cycle arrest in G1/S and G2/M phases and cell death by apoptotic induction. We demonstrate that the NDF from common bean modulates gene expression profiles in the colon tissue of AOM-induced rats, contributing to the chemoprotective effect of common bean on early-stage colon cancer. PMID:22916810

  4. Real-time analysis of multi-laser-beam fluorescence for timed control of laser tweezers in a microfluidic cell-sorting device

    NASA Astrophysics Data System (ADS)

    Davis, Lloyd M.; Lubbeck, Jennifer L.; Dean, Kevin M.; Palmer, Amy E.; Jimenez, Ralph

    2012-10-01

    We have developed a microfluidic cell sorter for mammalian cells expressing intrinsic fluorescent proteins that enables selection of cells with proteins that have enhanced photophysical properties, such as reduced fluorescence photobleaching and/or reversible dark state conversion. Previous ensemble imaging studies have used an acousto-optic modulator (AOM) to provide millisecond pulsed laser illumination for in vivo assays that distinguish reversible darkstate conversion from irreversible photobleaching. However, in the sorter, cells are hydrodynamically focused into a stream, which flows through a series of 4 or 8 line-focused, continuous, 532 nm laser beams, such that each cell experiences a similar millisecond modulated excitation. The amplitude and timing of the fluorescence response from each of the beams are measured by a red-sensitive photomultiplier and analyzed in real time to separately determine initial fluorescence brightness and photobleaching characteristics. In addition, each cell's flow speed is found from its time of passage through the beams, and if the analysis results are within adjustable limits, a 1064 nm optical trap beam is switched on and moved along an intersecting trajectory at a matching speed, so that the cell becomes deflected by the optical gradient forces towards another exit channel of the microfluidic device. The optical sorting of cells is similar to that demonstrated by others, except that the motion of the trap beam is achieved using a piezo mirror under computer control, rather than an AOM; also, rather than a single-beam brightness measure using a hardwired circuit, a more complex multi-beam analysis is performed in software using the Real-Time module of LabView (National Instruments) on a separate computer to achieve deterministic timing and low latency. The software displays updated statistics of the sort, obtained by counting cells that pass through an extra laser beam in the exit channel. A mixture of cells expressing

  5. Development and Deployment of a Compact Eye-Safe Scanning Differential absorption Lidar (DIAL) for Spatial Mapping of Carbon Dioxide for Monitoring/Verification/Accounting at Geologic Sequestration Sites

    SciTech Connect

    Repasky, Kevin

    2014-03-31

    A scanning differential absorption lidar (DIAL) instrument for monitoring carbon dioxide has been developed. The laser transmitter uses two tunable discrete mode laser diodes (DMLD) operating in the continuous wave (cw) mode with one locked to the online absorption wavelength and the other operating at the offline wavelength. Two in-line fiber optic switches are used to switch between online and offline operation. After the fiber optic switch, an acousto- optic modulator (AOM) is used to generate a pulse train used to injection seed an erbium doped fiber amplifier (EDFA) to produce eye-safe laser pulses with maximum pulse energies of 66 {micro}J, a pulse repetition frequency of 15 kHz, and an operating wavelength of 1.571 {micro}m. The DIAL receiver uses a 28 cm diameter Schmidt-Cassegrain telescope to collect that backscattered light, which is then monitored using a photo-multiplier tube (PMT) module operating in the photon counting mode. The DIAL instrument has been operated from a laboratory environment on the campus of Montana State University, at the Zero Emission Research Technology (ZERT) field site located in the agricultural research area on the western end of the Montana State University campus, and at the Big Sky Carbon Sequestration Partnership site located in north-central Montana. DIAL data has been collected and profiles have been validated using a co-located Licor LI-820 Gas Analyzer point sensor.

  6. Phase Analysis for Frequency Standards in the Microwave and Optical Domains.

    PubMed

    Kazda, Michael; Gerginov, Vladislav; Huntemann, Nils; Lipphardt, Burghard; Weyers, Stefan

    2016-07-01

    Coherent manipulation of atomic states is a key concept in high-precision spectroscopy and used in atomic fountain clocks and a number of optical frequency standards. Operation of these standards can involve a number of cyclic switching processes, which may induce cycle-synchronous phase excursions of the interrogation signal and thus lead to shifts in the output of the frequency standard. We have built a field-programmable gate array (FPGA)-based phase analyzer to investigate these effects and conducted measurements on two kinds of frequency standards. For the caesium fountains PTB-CSF1 and PTB-CSF2, we were able to exclude phase variations of the microwave source at the level of a few microradians, corresponding to relative frequency shifts of less than [Formula: see text]. In the optical domain, we investigated phase variations in PTB's Yb (+) optical frequency standard and made detailed measurements of acousto-optic modulator (AOM) chirps and their scaling with duty cycle and driving power. We ascertained that cycle-synchronous as well as long-term phase excursion do not cause frequency shifts larger than [Formula: see text]. PMID:26761607

  7. Precision frequency measurement of 1S0-3P1 intercombination lines of Sr isotopes

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Gao, Feng; Ye-Bing, Wang; Xiao, Tian; Jie, Ren; Ben-Quan, Lu; Qin-Fang, Xu; Yu-Lin, Xie; Hong, Chang

    2015-01-01

    We report on frequency measurement of the intercombination (5s2)1S0-(5s5p)3P1 transition of the four natural isotopes of strontium, including 88Sr (82.58%), 87Sr (7.0%), 86Sr (9.86%), and 84Sr (0.56%). A narrow-linewidth laser that is locked to an ultra-low expansion (ULE) optical cavity with a finesse of 12000 is evaluated at a linewidth of 200 Hz with a fractional frequency drift of 2.8×10-13 at an integration time of 1 s. The fluorescence collector and detector are specially designed, based on a thermal atomic beam. Using a double-pass acousto-optic modulator (AOM) combined with a fiber and laser power stabilization configuration to detune the laser frequency enables high signal-to-noise ratios and precision saturated spectra to be obtained for the six transition lines, which allows us to determine the transition frequency precisely. The optical frequency is measured using an optical frequency synthesizer referenced to an H maser. Both the statistical values and the final values, including the corrections and uncertainties, are derived for a comparison with the values given in other works. Project supported by the National Natural Science Foundation of China (Grant No. 61127901) and the Key Project of the Chinese Academy of Sciences (Grant No. KJZD-EW-W02).

  8. Latest Results from the LTX High-Speed Digital Holography System

    NASA Astrophysics Data System (ADS)

    Thomas, C. E., Jr.; Granstedt, E. M.; Jacobson, C. M.; Lundberg, D. P.; Majeski, R.; Kaita, R.; Baylor, L. R.; Combs, S. K.; Meitner, S. J.; Rasmussen, D. A.

    2012-10-01

    During the last year research efforts for the LTX Digital Holography system have been concentrated on reducing noise and producing sample images. A high-speed CO2 laser digital holography system (500 frames per second (FPS) at 256 x 256 pixels, 1500 FPS at 128 x 128 pixels, etc., to a maximum of 43,000 FPS at 64 x 4 pixels) has been built for high-resolution imaging of electron density on the Lithium Tokamak Experiment (LTX). The laser operates at 9.1 microns by using an Oxygen-18 isotope, and has a power output up to 20 W. A FLIR SC4000 IR camera is used to capture the digital holograms. An acousto-optic modulator (AOM) is used to ``shutter'' the laser so that effective camera integration times down to less than one microsecond are possible. The system will be used for imaging measurements on LTX during molecular cluster injection (MCI), supersonic gas injection (SGI), and external gas injection. Results of noise reduction efforts along with sample images and any LTX results will be presented.

  9. Latest Results from the LTX High-Speed Digital Holography System

    NASA Astrophysics Data System (ADS)

    Thomas, C. E. (Tommy), Jr.; Granstedt, E. M.; Jacobson, C. M.; Majeski, R.; Kaita, R.; Baylor, L. R.; Combs, S. K.; Meitner, S. J.; Rasmussen, D. A.

    2013-10-01

    During the last year research efforts for the LTX Digital Holography system have been concentrated on reducing noise and diagnosing the flow pattern of the LTX Supersonic Gas Injector. A high-speed CO2 laser digital holography system (500 frames per second (FPS) at 256 × 256 pixels, 1500 FPS at 128 × 128 pixels, etc., to a maximum of 43,000 FPS at 64 × 4 pixels) has been built for high-resolution imaging of electron density on the Lithium Tokamak Experiment (LTX). The laser operates at 9.1 microns by using an Oxygen-18 isotope, and has a power output up to 20 W. A FLIR SC4000 IR camera is used to capture the digital holograms. An acousto-optic modulator (AOM) is used to ``shutter'' the laser so that effective camera integration times down to less than one microsecond are possible. The system will be used for imaging measurements on LTX during molecular cluster injection (MCI), supersonic gas injection (SGI), and injection from edge gas puffers. Results of noise reduction efforts along with ultra low noise flow-pattern images from the SGI will be presented. Partial Support from USDOE Contract DE-AC02-09CH11466 and USDOE Grant DE-FG02-07ER84724 is gratefully acknowledged.

  10. Results from the LTX High-Speed Digital Holography System

    NASA Astrophysics Data System (ADS)

    Thomas, C. E. (Tommy), Jr.; Baylor, L. R.; Combs, S. K.; Meitner, S. J.; Rasmussen, D. A.; Granstedt, E. M.; Lundberg, D. P.; Jacobson, C. M.; Majeski, R.; Kaita, R.

    2011-10-01

    A high-speed CO2 laser digital holography system (500 frames per second (FPS) at 256 x 256 pixels, 1500 FPS at 128 x 128 pixels, etc., to a maximum of 43,000 FPS at 64 x 4 pixels) has been built for high-resolution imaging of electron density on the Lithium Tokamak Experiment (LTX). The laser operates at 9.1 microns by using an Oxygen-18 isotope, and has a power output up to 20 W. A FLIR SC4000 IR camera is used to capture the digital holograms. An acousto-optic modulator (AOM) is used to ``shutter'' the laser so that effective camera integration times down to less than one microsecond are possible. The system will be used for examining profile modifications on LTX with molecular cluster injection (MCI), supersonic gas injection (SGI), and external gas puffing. Results of measurements will be presented along with a discussion of system design, including noise-reduction techniques developed during system testing and initial operation. Partial Support from USDOE Contract DE-AC02-09CH11466 and USDOE Grant DE-FG02-07ER84724 is gratefully acknowledged.

  11. Heterodyne Interferometer with Angstrom-level Periodic Nonlinearity

    SciTech Connect

    Schmitz, Tony L.; Beckwith, John F.

    2005-01-25

    Displacement measuring interferometer systems and methods are disclosed. One or more acousto-optic modulators for receiving a laser light beam from a laser light source can be utilized to split the laser light beam into two or more laser light beams, while spatially separating frequencies thereof. One or more reflective mechanisms can be utilized to reflect one or more of the laser light beams back to the acoustooptic modulator. Interference of two or more of the laser light beams generally at the acousto-optic modulator can provide an interfered laser light beam thereof. A detector for receiving the interfered laser light beam can be utilized to provide interferometer measurement data.

  12. Heterodyne interferometer with angstrom-level periodic nonlinearity

    DOEpatents

    Schmitz, Tony L.; Beckwith, John F.

    2005-01-25

    Displacement measuring interferometer systems and methods are disclosed. One or more acousto-optic modulators for receiving a laser light beam from a laser light source can be utilized to split the laser light beam into two or more laser light beams, while spatially separating frequencies thereof. One or more reflective mechanisms can be utilized to reflect one or more of the laser light beams back to the acousto-optic modulator. Interference of two or more of the laser light beams generally at the acousto-optic modulator can provide an interfered laser light beam thereof. A detector for receiving the interfered laser light beam can be utilized to provide interferometer measurement data.

  13. Near Infrared Cavity Ring-Down Spectroscopy for Isotopic Analyses of CH4 on Future Martian Surface Missions

    NASA Technical Reports Server (NTRS)

    Chen, Y.; Mahaffy P.; Holmes, V.; Burris, J.; Morey, P.; Lehmann, K.K.; Lollar, B. Sherwood; Lacrampe-Couloume, G.; Onstott, T.C.

    2014-01-01

    A compact Near Infrared Continuous Wave Cavity Ring-Down Spectrometer (near-IR-cw-CRDS) was developed as a candidate for future planetary surface missions. The optical cavity was made of titanium with rugged quartz windows to protect the delicate super cavity from the harsh environmental changes that it would experience during space flight and a Martian surface mission. This design assured the long-term stability of the system. The system applied three distributed feedback laser diodes (DFB-LD), two of which were tuned to the absorption line peaks of (sup 12)CH4 and (sup 13)CH4 at 6046.954 inverse centimeters and 6049.121 inverse centimeters, respectively. The third laser was tuned to a spectral-lines-free region for measuring the baseline cavity loss. The multiple laser design compensated for typical baseline drift of a CRDS system and, thus, improved the overall precision. A semiconductor optical amplifier (SOA) was used instead of an Acousto-Optic Module (AOM) to initiate the cavity ring-down events. It maintained high acquisition rates such as AOM, but consumed less power. High data acquisition rates combined with improved long-term stability yielded precise isotopic measurements in this near-IR region even though the strongest CH4 absorption line in this region is 140 times weaker than that of the strongest mid-IR absorption band. The current system has a detection limit of 1.4 times 10( sup –12) inverse centimeters for (sup 13)CH4. This limit corresponds to approximately 7 parts per trillion volume of CH4 at 100 Torrs. With no further improvements the detection limit of our current near IR-cw-CRDS at an ambient Martian pressure of approximately 6 Torrs (8 millibars) would be 0.25 parts per billion volume for one 3.3 minute long analysis.

  14. Near infrared cavity ring-down spectroscopy for isotopic analyses of CH4 on future Martian surface missions

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Mahaffy, P.; Holmes, V.; Burris, J.; Morey, P.; Lehmann, K. K.; Sherwood Lollar, B.; Lacrampe-Couloume, G.; Onstott, T. C.

    2015-01-01

    A compact Near Infrared Continuous Wave Cavity Ring-down Spectrometer (near-IR-cw-CRDS) was developed as a candidate for future planetary surface missions. The optical cavity was made of titanium with rugged quartz windows to protect the delicate super cavity from the harsh environmental changes that it would experience during space flight and a Martian surface mission. This design assured the long-term stability of the system. The system applied three distributed feedback laser diodes (DFB-LD), two of which were tuned to the absorption line peaks of 12CH4 and 13CH4 at 6046.954 cm-1 and 6049.121 cm-1, respectively. The third laser was tuned to a spectral-lines-free region for measuring the baseline cavity loss. The multiple laser design compensated for typical baseline drift of a CRDS system and, thus, improved the overall precision. A semiconductor optical amplifier (SOA) was used instead of an Acousto-Optic Module (AOM) to initiate the cavity ring-down events. It maintained high acquisition rates such as AOM, but consumed less power. High data acquisition rates combined with improved long-term stability yielded precise isotopic measurements in this near-IR region even though the strongest CH4 absorption line in this region is 140 times weaker than that of the strongest mid-IR absorption band., The current system has a detection limit of 1.4×10-12 cm-1 for 13CH4. This limit corresponds to ~7 pptv of CH4 at 100 Torr. With no further improvements the detection limit of our current near IR-cw-CRDS at an ambient Martian pressure of ~6 Torr (8 mbar) would be 0.25 ppbv for one 3.3 minute long analysis.

  15. Comparisons of 2D IR measured spectral diffusion in rotating frames using pulse shaping and in the stationary frame using the standard method.

    PubMed

    Karthick Kumar, S K; Tamimi, A; Fayer, M D

    2012-11-14

    Multidimensional visible spectroscopy using pulse shaping to produce pulses with stable controllable phases and delays has emerged as an elegant tool to acquire electronic spectra faster and with greatly reduced instrumental and data processing errors. Recent migration of this approach using acousto-optic modulator (AOM) pulse shaping to the mid-infrared region has proved useful for acquiring two dimensional infrared (2D IR) vibrational echo spectra. The measurement of spectral diffusion in 2D IR experiments hinges on obtaining accurate 2D line shapes. To date, pulse shaping 2D IR has not been used to study the time-dependent spectral diffusion of a vibrational chromophore. Here we compare the spectral diffusion data obtained from a standard non-collinear 2D IR spectrometer using delay lines to the data obtained from an AOM pulse shaper based 2D IR spectrometer. The pulse shaping experiments are performed in stationary, partially rotating, and fully rotating reference frames and are the first in the infrared to produce 2D spectra collected in a fully rotating frame using a phase controlled pulse sequence. Rotating frame experiments provide a dramatic reduction in the number of time points that must be measured to obtain a 2D IR spectrum, with the fully rotating frame giving the greatest reduction. Experiments were conducted on the transition metal carbonyl complex tricarbonylchloro(1,10-phenanthroline)rhenium(I) in chloroform. The time dependent data obtained from the different techniques and with different reference frames are shown to be in agreement. PMID:23163363

  16. Application thinking on Bian-stone of the acousto-optic effect in the treatment of primary dysmenorrhea

    NASA Astrophysics Data System (ADS)

    Ge, Shu; Chen, Gui-Zhen; Liu, Song-Hao

    2009-08-01

    In order to identify the relations between the Si-Bin Bian-stone of the mineral composition characteristics and Bian-stone of the good infrared emission features. A detailed study of the Sibin Bian-stone samples was conducted by using the laser Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM). The study is to provide theoretical physical support for Bian-stone in the treatment of primary dysmenorrhea. And Thermal tomography technology (TTM) is intended to be carried out to assess the effects of Bian-stone. The Raman spectroscopic study confirmed the existence of fine-grained pyrite, anatase, calcitepyrite and graphite. It is believed that the combination of good thermal properties of the above 4 minerals make the Sibin Bian-stone as a useful material with very good physiotherapical functions. The ultrasonic has a resonance with the body's biological molecules so that it can improve meridians microcirculation. Hence, the Sibin Bian-stones can be used to make acupuncture tools for stimulating the circulation of the blood in vessels and relieving pains of human beings by utilizing its infrared thermal radiation property. TTM which accepts the heat produced by the metabolism process of life can reflect the energy status information, TTM will be introduced to evaluate effect at the overall level of the abdomen from the thermal image and analyze to derive a comprehensive diagnosis. In sum, this experiment is explored to provide a new idea for the modernization of traditional Chinese medicine.

  17. Use of acousto-optic grating as a sensor for determining the adulteration in liquids being used in daily life

    NASA Astrophysics Data System (ADS)

    Soni, Kirti; Kasana, R. S.

    2008-01-01

    An optical sensor has been developed for finding the proportional composition of two liquids in a mixture. The variation of the refractive index of a liquid produces light diffraction phenomenon. A liquid mixture is filled in a rectangular glass cell, which is placed orthogonically to the incident collimated beams of light. This cell consists of a piezoelectric crystal vibrator for generating ultrasonic waves. The collimated light while passing through this cell gets diffracted. The diffracted dots are collected by a converging lens and displayed in the back focal plane of the lens. The location of the diffracted dots decide the composition of mixture constituents namely fuel oils, edible oils, wine, water, etc. Thus, the adulteration of various liquids can be determined by having the knowledge of the position of diffraction dots.

  18. Acousto-optic effect in a nematic liquid-crystal layer under the binary effect of sound and viscous waves

    SciTech Connect

    Kozhevnikov, E. N.

    2010-03-15

    The optical effect in a liquid crystal cell containing a homeotropic layer of nematic liquid crystal (NLC) is analyzed. An NLC layer, located between crossed polaroids and opaque in the absence of external effect, is cleared after irradiation by an ultrasonic beam with a sharp spatial boundary. This enlightenment is suggested to be caused by the reorientation of crystal molecules in the acoustic flows that arise under the binary effect of the layer compression in the irradiated region and the viscous waves propagating from the layer boundaries. The flows were calculated taking into account the stress caused by the velocity convection and crystal structure relaxation. An expression is derived for the cell transparency, and the relative role of the convection and relaxation processes in the effect is determined.

  19. Calibration of a wide-field frequency-domain fluorescence lifetime microscopy system using light emitting diodes as light sources.

    PubMed

    Elder, A D; Frank, J H; Swartling, J; Dai, X; Kaminski, C F

    2006-11-01

    High brightness light emitting diodes are an inexpensive and versatile light source for wide-field frequency-domain fluorescence lifetime imaging microscopy. In this paper a full calibration of an LED based fluorescence lifetime imaging microscopy system is presented for the first time. A radio-frequency generator was used for simultaneous modulation of light emitting diode (LED) intensity and the gain of an intensified charge coupled device (CCD) camera. A homodyne detection scheme was employed to measure the demodulation and phase shift of the emitted fluorescence, from which phase and modulation lifetimes were determined at each image pixel. The system was characterized both in terms of its sensitivity to measure short lifetimes (500 ps to 4 ns), and its capability to distinguish image features with small lifetime differences. Calibration measurements were performed in quenched solutions containing Rhodamine 6G dye and the results compared to several independent measurements performed with other measurement methodologies, including time correlated single photon counting, time gated detection, and acousto optical modulator (AOM) based modulation of excitation sources. Results are presented from measurements and simulations. The effects of limited signal-to-noise ratios, baseline drifts and calibration errors are discussed in detail. The implications of limited modulation bandwidth of high brightness, large area LED devices ( approximately 40 MHz for devices used here) are presented. The results show that phase lifetime measurements are robust down to sub ns levels, whereas modulation lifetimes are prone to errors even at large signal-to-noise ratios. Strategies for optimizing measurement fidelity are discussed. Application of the fluorescence lifetime imaging microscopy system is illustrated with examples from studies of molecular mixing in microfluidic devices and targeted drug delivery research. PMID:17204064

  20. Optical Channelizer Evaluation Using Empirical Data and Simulation

    NASA Technical Reports Server (NTRS)

    Ivancic,William D.

    1998-01-01

    Westinghouse Electric Corporation Division under NASA contract NAS3-25865 developed a proof-of-concept (POC) multichannel demultiplexer implemented as an acousto-optic radiofrequency (RF) with a spectrum analyzer. A detailed analysis of the experimental results indicate that the expected degradation caused by the acousto-optical channelizer is approximately 2.0 dB degradation at 10(exp -5) bit-error rate (BER) and 3.0 dB degradation at 10(exp -8) BER. This degradation may be quite acceptable when considering the excellent volume, mass, and power characteristics of acousto-optical channelizing relative to other technologies. In addition, system performance can be greatly improved by using digital pulse shaping in the modem and increasing the channel spacing from 40 to 45 kHz for 64 kbps quadrature phase-shift keying (QPSK) modulation.

  1. Module Configuration

    DOEpatents

    Oweis, Salah; D'Ussel, Louis; Chagnon, Guy; Zuhowski, Michael; Sack, Tim; Laucournet, Gaullume; Jackson, Edward J.

    2002-06-04

    A stand alone battery module including: (a) a mechanical configuration; (b) a thermal management configuration; (c) an electrical connection configuration; and (d) an electronics configuration. Such a module is fully interchangeable in a battery pack assembly, mechanically, from the thermal management point of view, and electrically. With the same hardware, the module can accommodate different cell sizes and, therefore, can easily have different capacities. The module structure is designed to accommodate the electronics monitoring, protection, and printed wiring assembly boards (PWAs), as well as to allow airflow through the module. A plurality of modules may easily be connected together to form a battery pack. The parts of the module are designed to facilitate their manufacture and assembly.

  2. Frequency noise in frequency swept fiber laser.

    PubMed

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2013-04-01

    This Letter presents a measurement of the spectral content of frequency shifted pulses generated by a lightwave synthesized frequency sweeper. We found that each pulse is shifted in frequency with very high accuracy. We also discovered that noise originating from light leaking through the acousto- optical modulators and forward propagating Brillouin scattering appear in the spectrum. PMID:23546253

  3. Heterodyne holography with full control of both the signal and reference arms.

    PubMed

    Gross, Michel

    2016-01-20

    Heterodyne holography is a variant of phase-shifting holography in which the reference and signal arms are controlled by acousto-optic modulators. In this review paper, we will briefly describe the method and its properties, and we will illustrate its advantages in experimental applications. PMID:26835961

  4. Blueberry consumption inhibits gastrointestinal tumorigenesis in AOM-treated rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Epidemiological studies show inverse or no association of fruit consumption with relative risk for colorectal cancers. Such studies did not examine specific fruits and in particular, those enriched in polyphenols with high antioxidant capacities. We examined blueberry (BB), a fruit rich in anthocy...

  5. Singlet-triplet annihilation in single LHCII complexes.

    PubMed

    Gruber, J Michael; Chmeliov, Jevgenij; Krüger, Tjaart P J; Valkunas, Leonas; van Grondelle, Rienk

    2015-08-14

    In light harvesting complex II (LHCII) of higher plants and green algae, carotenoids (Cars) have an important function to quench chlorophyll (Chl) triplet states and therefore avoid the production of harmful singlet oxygen. The resulting Car triplet states lead to a non-linear self-quenching mechanism called singlet-triplet (S-T) annihilation that strongly depends on the excitation density. In this work we investigated the fluorescence decay kinetics of single immobilized LHCIIs at room temperature and found a two-exponential decay with a slow (3.5 ns) and a fast (35 ps) component. The relative amplitude fraction of the fast component increases with increasing excitation intensity, and the resulting decrease in the fluorescence quantum yield suggests annihilation effects. Modulation of the excitation pattern by means of an acousto-optic modulator (AOM) furthermore allowed us to resolve the time-dependent accumulation and decay rate (∼7 μs) of the quenching species. Inspired by singlet-singlet (S-S) annihilation studies, we developed a stochastic model and then successfully applied it to describe and explain all the experimentally observed steady-state and time-dependent kinetics. That allowed us to distinctively identify the quenching mechanism as S-T annihilation. Quantitative fitting resulted in a conclusive set of parameters validating our interpretation of the experimental results. The obtained stochastic model can be generalized to describe S-T annihilation in small molecular aggregates where the equilibration time of excitations is much faster than the annihilation-free singlet excited state lifetime. PMID:26156159

  6. Constant peak-power single-frequency linearly-polarized all-fiber laser for coherent detection based on closed-loop feedback technology

    NASA Astrophysics Data System (ADS)

    Ding, Yaqian; Zhang, Xiang; Li, Dong; Wang, Dapeng; Zhang, Renzhong; Song, Chengying; Che, Haozhao; Wang, Rui; Guo, Baoling; Chen, Guanghui

    2015-10-01

    In this paper, a practical single-frequency high-repetition linearly-polarized eye-safe all-fiber laser with constant peak power is demonstrated. It is based on master-oscillator power amplifier (MOPA) system. A distributed feedback laser diode simulating at 1550nm with narrow linewidth of 2.3 kHz is employed as the seed source. It is modulated to a pulse laser with high repetition of 20 kHz and peak power of 10mW by an acousto-optic modulator (AOM). The pulse width is tunable between 100ns to 400ns. Two-stage cascade amplifier is established, which consists of a pre-amplifier and a power-amplifier. Amplified spontaneous emission (ASE) and stimulated billion scattering are well suppressed by special management. The output peak power of 30W is obtained, which has nearly diffraction-limited beam quality. It operates in linewidth of 1.2MHz, polarization-extinction ratio (PER) of 25dB and signal-to-noise ratio (SNR) of more than 40dB. Gain of the whole amplifier achieves nearly 35dB. Furthermore, an embedded control system (ECS) based on the WinCE operating system (OS) and the chip of S3C2440 is proposed. This control system based on closed-loop feedback technology makes the peak power keeping constant even the pulse width tunable, which is convenient for the end user of the radar. This robust portable laser is remarkable and fulfills the desire of coherent detection excellently.

  7. Firefighting Module

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Aviation Power Supply's mobile firefighting module called Firefly II is mounted on a trailer pulled by a pickup truck. Trailer unit has two three- inch water cannons, and the pickup carries a six inch cannon. Completely self contained, module pumps 3,000 gallons of water a minute from hydrants or open bodies of water. Stream can go as far as 400 feet or can be employed in a high-loft mode to reach the tops of tall refinery towers. Compact Firefly II weighs only 2,500 pounds when fully fueled. Key component is a specially designed two stage pump. Power for the pump is generated by a gas turbine engine. Module also includes an electronic/pump controller, multiple hose connections, up to 1,500 feet of hose and fuel for four hours operation. Firefly trailer can be backed onto specially-built large fireboat.

  8. Firefighting Module

    NASA Astrophysics Data System (ADS)

    1980-01-01

    Aviation Power Supply's mobile firefighting module called Firefly II is mounted on a trailer pulled by a pickup truck. Trailer unit has two three- inch water cannons, and the pickup carries a six inch cannon. Completely self contained, module pumps 3,000 gallons of water a minute from hydrants or open bodies of water. Stream can go as far as 400 feet or can be employed in a high-loft mode to reach the tops of tall refinery towers. Compact Firefly II weighs only 2,500 pounds when fully fueled. Key component is a specially designed two stage pump. Power for the pump is generated by a gas turbine engine. Module also includes an electronic/pump controller, multiple hose connections, up to 1,500 feet of hose and fuel for four hours operation. Firefly trailer can be backed onto specially-built large fireboat.

  9. Thermionic modules

    DOEpatents

    King, Donald B.; Sadwick, Laurence P.; Wernsman, Bernard R.

    2002-06-18

    Modules of assembled microminiature thermionic converters (MTCs) having high energy-conversion efficiencies and variable operating temperatures manufactured using MEMS manufacturing techniques including chemical vapor deposition. The MTCs incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. The MTCs also exhibit maximum efficiencies of just under 30%, and thousands of the devices and modules can be fabricated at modest costs.

  10. Towards mitigating explosive threats using quantum controlled initiation

    SciTech Connect

    Greenfield, Margo T; Mc Grane, Shawn D; Moore, David S; Scharff, R. Jason

    2010-12-08

    Quantum control of localized energy deposition into an energetic material is being investigated as a method to allow controlled initiation and propagation of action without transition to detonation. Quantum controlled initiation (QCI) of explosives utilize time dependent phase shaped ultraviolet (UV) electric fields to drive the energetic chemical systems towards reaction. QCI searches for an optimally shaped ultrafast laser pulse that will guide energy flow along a desired path. QCI can be exploited as a stand-off mitigation technology that strives to reduce the impact of explosive blasts on people and property by initiating controlled low order reaction. Quantum controlled initiation experiments require: (1) optimally shaped light pulses, (2) pulse shaping measurement, (3) feedback control algorithms, and (4) feedback measurement methods. Femtosecond laser pulse shaping in the UV at 400 nm employs a fused silica acousto-optic modulator (AOM) pulse shaper that consists of a 4-f zero dispersion compressor. Tr sient absorption spectroscopy is used to measure the pulse shaper effects. Both global and local optimization search routines such as genetic algorithm, differential evolution, and downhill simplex are used to search for the optimal pulse shape. Hexanitroazobenzene (HNAB), Trinitroanaline (TNA) and Diaminoazozyfurazan (DAAF) are excited to the first electronic state with 400 nm light. Our initiation experiments are studying the effect of phase shaped 400 nm pulses on HNAB, TNA and DAAF. The transient absorption spectra for each material have been obtained and note worthy regions further investigated with single parameter control (second order spectral phase and energy). Many systems have simple intensity control such as that shown by DAAF. TNA and HNAB have spectral features that are not single parameter driven and are being further investigated to obtain fully optimized complex control.

  11. Towards understanding initiation reactions of explosives via ultrafast laser quantum control

    SciTech Connect

    Greenfield, Margo T; Mc Grane, Shawn D; Moore, David S; Scharff, R. Jason

    2010-12-08

    Optimal control can be utilized to control the initiation reaction of explosives, where time dependent phase shaped electric fields drive the chemical systems towards a desired state. For quantum controlled initiation (QCI) of explosives a pulse is created which seeks to achieve initiation by employing shaped ultraviolet light. QCI will enhance the understanding of energetic material reactions by yielding insight into the characteristics, such as critical 'hot spot' size and reaction dynamics, necessary for initiation. Quantum control experiments require the ability to: (1) phase and amplitude shape an ultrafast laser pulse, (2) measure the effect of pulse shape, and (3) optimize the desired outcome. Pulse shaping is performed with a 4-focal length dispersed fused silica acousto-optic modulator (AOM) at 400 nm in the ultraviolet (UV). Transient absorption spectroscopy is used to measure the pulse shape effects. Both global and local optimization search routines such as genetic algorithm, differential evolution, and downhill simplex are used to search for the optimal pulse shape. Hexanitroazobenzene (HNAB), Trinitroanaline (TNA) and Diaminoazozyfurazan (DAAF) are excited to the first electronic state with 400 nm light. Our initiation experiments are studying the effect of phase shaped 400 nm pulses on HNAB, TNA and DAAF. Novel transient absorption spectra for each material have been obtained and note worthy regions further investigated with single parameter control (second order spectral phase and energy). Many systems have simple intensity control such as that shown by DAAF. TNA and HNAB have spectral features that are not single parameter driven and are being further investigated with complex control.

  12. A novel fiber laser development for photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Yavas, Seydi; Aytac-Kipergil, Esra; Arabul, Mustafa U.; Erkol, Hakan; Akcaalan, Onder; Eldeniz, Y. Burak; Ilday, F. Omer; Unlu, Mehmet B.

    2013-03-01

    Photoacoustic microscopy, as an imaging modality, has shown promising results in imaging angiogenesis and cutaneous malignancies like melanoma, revealing systemic diseases including diabetes, hypertension, tracing drug efficiency and assessment of therapy, monitoring healing processes such as wound cicatrization, brain imaging and mapping. Clinically, photoacoustic microscopy is emerging as a capable diagnostic tool. Parameters of lasers used in photoacoustic microscopy, particularly, pulse duration, energy, pulse repetition frequency, and pulse-to-pulse stability affect signal amplitude and quality, data acquisition speed and indirectly, spatial resolution. Lasers used in photoacoustic microscopy are typically Q-switched lasers, low-power laser diodes, and recently, fiber lasers. Significantly, the key parameters cannot be adjusted independently of each other, whereas microvasculature and cellular imaging, e.g., have different requirements. Here, we report an integrated fiber laser system producing nanosecond pulses, covering the spectrum from 600 nm to 1100 nm, developed specifically for photoacoustic excitation. The system comprises of Yb-doped fiber oscillator and amplifier, an acousto-optic modulator and a photonic-crystal fiber to generate supercontinuum. Complete control over the pulse train, including generation of non-uniform pulse trains, is achieved via the AOM through custom-developed field-programmable gate-array electronics. The system is unique in that all the important parameters are adjustable: pulse duration in the range of 1-3 ns, pulse energy up to 10 μJ, repetition rate from 50 kHz to 3 MHz. Different photocoustic imaging probes can be excited with the ultrabroad spectrum. The entire system is fiber-integrated; guided-beam-propagation rendersit misalignment free and largely immune to mechanical perturbations. The laser is robust, low-cost and built using readily available components.

  13. 58 mJ burst containing ultra-short pulses with homogenous energy level from an Yb-doped fiber amplifier

    NASA Astrophysics Data System (ADS)

    Breitkopf, Sven; Klenke, Arno; Gottschall, Thomas; Otto, Hans-Jürgen; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    There is a great interest in obtaining laser pulses with a high average power as well as high pulse energies. Continuously pulsed systems face many problems to satisfy those requirements, independent on the amplifier concept. While many applications such as electron beam characterization and free-electron-laser seeding need high pulse energies at high repetition rates, they only need those laser pulses for a certain amount of time. Therefore, it is not necessary to run a laser system with continuous pulses at those parameters and a so-called burst mode might be sufficient and even essential in such cases. We report on a CPA-laser system, based on a large pitch fiber as a main-amplifier delivering bursts containing ultra-short, highly-energetic pulses. The burst rate is set to 20Hz, while each burst contains 2000 pulses at a pulse-repetition-rate of 10MHz and with a pulse-duration of 700fs. Hence the duty cycle D is 0.4%. To achieve a homogeneous pulse energy level between 27μJ and 31μJ after the compression, the main amplifier is pumped with a very high power of 1.6kW in a burst-mode (D=10%). By using an acousto-optical modulator (AOM) after the main-amp fiber, the residual output before and after the burst is removed to suppress ASE and any underground-pulses around the amplified burst. The limitations that could be observed during this experiment were mainly due to mode instabilities, which were detectable even on a very short time scale of a few hundred μs using a high speed camera.

  14. Multiple Isotope Magneto Optical Trap from a single diode laser

    NASA Astrophysics Data System (ADS)

    Gomez, Eduardo; Valenzuela, Victor; Hamzeloui, Saeed; Gutierrez, Monica

    2013-05-01

    We present a simple design for a Dual Isotope Magneto Optical Trap. The system requires a single diode laser, a fiber modulator and a tapered amplifier to trap and completely control both 85Rb and 87Rb. We generate all the frequencies needed for trapping both species using the fiber intensity modulator. All the frequencies are amplified simultaneously with the tapered amplifier. The position and power of each frequency is now controlled independently on the RF rather than on the optical side. This introduces an enormous simplification for laser cooling that often requires an acousto-optic modulator for each frequency. The range of frequency changes is much bigger than what is available with acousto-optic modulators since in our case is determined by the modulator bandwidth (10 GHz). Additional isotopes can be simply added by including additional RF frequencies to the modulator and extra beams for other uses can be produced the same way. Support from CONACYT, PROMEP and UASLP.

  15. Firefighting Module

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Firefly II pump module is NASA's Marshall Space Flight Center's commercial offshoot of a NASA/US Coast Guard program involving development of a lightweight, helicopter-transportable firefighting module for a quick response in combating shipboard or harbor fires. Operable on land or water, the Amphib One is equipped with 3 water cannons. When all 3 are operating, unit pumps more than 3,000 gallons a minute. Newly developed model used by U.S. Coast Guard can pump 5,000 gallons per minute. It was designed for applications such as firefighting onboard ship fires, emergency dockside water pumping, dewatering ships in danger of sinking, flood control, and emergency water supply at remote locations.

  16. Thermoelectric module

    DOEpatents

    Kortier, William E.; Mueller, John J.; Eggers, Philip E.

    1980-07-08

    A thermoelectric module containing lead telluride as the thermoelectric mrial is encapsulated as tightly as possible in a stainless steel canister to provide minimum void volume in the canister. The lead telluride thermoelectric elements are pressure-contacted to a tungsten hot strap and metallurgically bonded at the cold junction to iron shoes with a barrier layer of tin telluride between the iron shoe and the p-type lead telluride element.

  17. Two-dimensional RI spectroscopy: Automation with pulse shaping and application to amyloid folding

    NASA Astrophysics Data System (ADS)

    Shim, Sang-Hee

    Two dimensional infrared (2D IR) spectroscopy has proven itself as a unique tool for probing the structures and dynamics of chemical and biological systems. Now, 2D IR spectroscopy has progressed to the point of being a ready-to-operate method for general researchers to address novel scientific questions. For that purpose, this thesis includes three practices: inventing a technique for mid-infrared pulse shaping; developing an automated method of collecting 2D IR spectra; applying it to delineate the pathway of amyloid formation. First, we developed a means to shape femtosecond pulses in the mid-infrared using a germanium acousto-optic modulator (Ge AOM). The Ge AOM directly modulates the amplitude and phase of mid-IR light between 2-18 mum, producing intense shaped pulses with high resolution and good phase stability. Second, we combined the pulse shaper with a pump-probe geometry to develop a new method of 2D IR spectroscopy. The pump-probe geometry simplifies the optical setup and produces properly phased absorptive lineshapes without additional data processing. The pulse shaper not only reproduces most conventional methods, but also allows new pulse shapes and phase combinations to further enhance 2D IR spectroscopy. Moreover, eliminating moving parts accelerates data collection so that an entire 2D IR spectrum can be obtained in <1 sec. Such ease of use, versatility and speed of our pulse shaping 2D IR method enables more sophisticated and reliable experiments. Finally, we tracked amyloid formation of human Islet amyloid polypeptide (hIAPP), related to type II diabetes. By continuously scanning 2D IR spectra, we can follow the hIAPP fibril formation indefinitely by collecting data on-the-fly without reinitiating the aggregation for each data point. We used isotope-labeling to probe the structural evolution of six different residues along the 37-residue hIAPP peptide. By separately monitoring the six residues, we found that the peptides nucleate near the turn

  18. Photovoltaic module and module arrays

    DOEpatents

    Botkin, Jonathan; Graves, Simon; Lenox, Carl J. S.; Culligan, Matthew; Danning, Matt

    2012-07-17

    A photovoltaic (PV) module including a PV device and a frame. The PV device has a PV laminate defining a perimeter and a major plane. The frame is assembled to and encases the laminate perimeter, and includes leading, trailing, and side frame members, and an arm that forms a support face opposite the laminate. The support face is adapted for placement against a horizontal installation surface, to support and orient the laminate in a non-parallel or tilted arrangement. Upon final assembly, the laminate and the frame combine to define a unitary structure. The frame can orient the laminate at an angle in the range of 3.degree.-7.degree. from horizontal, and can be entirely formed of a polymeric material. Optionally, the arm incorporates integral feature(s) that facilitate interconnection with corresponding features of a second, identically formed PV module.

  19. Photovoltaic module and module arrays

    DOEpatents

    Botkin, Jonathan; Graves, Simon; Lenox, Carl J. S.; Culligan, Matthew; Danning, Matt

    2013-08-27

    A photovoltaic (PV) module including a PV device and a frame, The PV device has a PV laminate defining a perimeter and a major plane. The frame is assembled to and encases the laminate perimeter, and includes leading, trailing, and side frame members, and an arm that forms a support face opposite the laminate. The support face is adapted for placement against a horizontal installation surface, to support and orient the laminate in a non-parallel or tilted arrangement. Upon final assembly, the laminate and the frame combine to define a unitary structure. The frame can orient the laminate at an angle in the range of 3.degree.-7.degree. from horizontal, and can be entirely formed of a polymeric material. Optionally, the arm incorporates integral feature(s) that facilitate interconnection with corresponding features of a second, identically formed PV module.

  20. Using a piezoelectric fiber stretcher to remove the depth ambiguity in optical Fourier domain imaging

    NASA Astrophysics Data System (ADS)

    Vergnole, Sébastien; Lamouche, Guy; Dufour, Marc; Gauthier, Bruno

    2007-07-01

    This paper reports the study of an Optical Fourier Domain Imaging (OFDI) setup for optical coherence tomography. One of the main drawbacks of OFDI is its inability to differentiate positive and negative depths. Some setups have already been proposed to remove this depth ambiguity by introducing a modulation by means of electro-optic or acousto-optic modulators. In our setup, we implement a piezoelectric fiber stretcher to generate a periodic phase shift between successive A-scans, thus introducing a transverse modulation. The depth ambiguity is then resolved by performing a Fourier treatment in the transverse direction before processing the data in the axial direction. It is similar to the B-M mode scanning already proposed for Spectral-Domain OCT1 but with a more efficient experimental setup. We discuss the advantages and the drawbacks of our technique compared to the technique based on acousto-optics modulators by comparing images of an onion obtained with both techniques.

  1. Supported PV module assembly

    SciTech Connect

    Mascolo, Gianluigi; Taggart, David F.; Botkin, Jonathan D.; Edgett, Christopher S.

    2013-10-15

    A supported PV assembly may include a PV module comprising a PV panel and PV module supports including module supports having a support surface supporting the module, a module registration member engaging the PV module to properly position the PV module on the module support, and a mounting element. In some embodiments the PV module registration members engage only the external surfaces of the PV modules at the corners. In some embodiments the assembly includes a wind deflector with ballast secured to a least one of the PV module supports and the wind deflector. An array of the assemblies can be secured to one another at their corners to prevent horizontal separation of the adjacent corners while permitting the PV modules to flex relative to one another so to permit the array of PV modules to follow a contour of the support surface.

  2. Acousto-optic tunable filter near-infrared spectroscopy for in-line monitoring liquid-liquid extraction of Gardenia jasminoides Ellis based on statistical analysis.

    PubMed

    Wu, Sha; Jin, Ye; Liu, Qi-An; Wu, Jian-Xiong; Bi, Yu-An; Wang, Zhen-Zhong; Xiao, Wei

    2015-10-01

    This study aimed to monitor liquid-liquid extraction of Gardenia jasminoides Ellis (Zhizi in Chinese) using in-line near-infrared spectroscopy. Shanzhiside (SZS), deacetyl asperulosidic acid methyl ester (DAAME), genipin-1-β-D-gentiobioside (GG), geniposide (GS), total acids (TA) and soluble solid content (SSC) were selected as quality control indicators, and measured by reference methods. Both partial least-squares regression (PLSR) and back propagation artificial neural networks (BP-ANN) were applied to create models to predict the content of above indicators. Paired-samples t-test and nonparametric test were used to compare differences in predictive values between two models of each indicator. Relative standard error of prediction (RSEP) and mean absolute percentage error (MAPE) were used to evaluate the predictive accuracy of the established models. The results showed that there was no significant difference in predicting DAAME, GS and TA between two models. However, PLSR model gave better accuracy in predicting GG and SZS than BP-ANN model. The BP-ANN model of SSC was better than PLSR model. This study shows that NIR spectroscopy can be used for rapid and accurate analysis of quality control indicators in the liquid-liquid extraction of Zhizi. Simultaneously, this study can serve as technical support for the application of NIR spectroscopy in the industrial production process. PMID:26601419

  3. High-power high-efficiency acousto-optically Q-switched rod Nd:YAG laser with 885 nm diode laser pumping

    NASA Astrophysics Data System (ADS)

    Liu, K.; Li, F. Q.; Xu, H. Y.; Wang, Z. C.; Zong, N.; Du, S. F.; Bo, Y.; Peng, Q. J.; Cui, D. F.; Xu, Z. Y.

    2013-01-01

    We have demonstrated a compact Q-switched Nd:YAG laser at 1064 nm with 885 nm diode-laser (LD) direct pumping. At a repetition rate of 100 kHz, an average output power of 53 W with beam quality factor M2 of 1.6 was achieved under the absorbed pump power of 122 W, corresponding to an optical-optical efficiency of 43.5% and a slope efficiency of 57.6%, respectively. The pulse width and the peak power at this output power were 112 ns and 4.74 kW, respectively.

  4. The GTR-KTP intracavity optical parametric oscillator driven by a diode-end-pumped acousto-optical Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Huang, H. T.; Zhang, B. T.; He, J. L.

    2013-03-01

    An efficient eye-safe gray-trace resistance-KTP (GTR-KTP) intracavity optical parametric oscillator (IOPO) excited by a diode-end-pumped Q-switched Nd:YAG laser was demonstrated. Under a laser diode power of 11.4 W, a maximum average output power of 1.2 W at 1572 nm was obtained at a repetition rate of 15 kHz, corresponding to a diode-to-signal conversion efficiency of 10.5%. As for the common KTP IOPO under the same pump conditions and cavity design, a lower average output power of 0.96 W was obtained. Consequently, the corresponding GTR-KTP OPO conversion efficiency was increased by 25% compared with that obtained in common KTP IOPO.

  5. Optical Bistability And Hysteresis In A Solid State Ring Laser

    NASA Astrophysics Data System (ADS)

    Kornienko, L. S.; Kravtsov, N. S.; Shelaev, A. N.

    1985-01-01

    The phenomena of optical bistability, hysteresis and memory under the interaction of oppositely directed (OD) light waves in a CW YAG:Nd3+ solid state ring laser (SRL) have been experimentally discovered. The possibilities of spontaneous or forced (with modulated SRL parameters) commutation of the radiation direction without transients at the relaxation frequency (typical for solid state lasers) have been established both in the single-mode and in the mode-locking regimes with various feedback circuits. The mode-locking band was found to be substantially broadened by more than an order of magnitude when OD light waves primarily diffracted on a standing ultrasonic wave were returned into the acousto-optical modulator. With such acousto-optical feedback the mode-locking regime has been obtained using a modulator on a running ultrasonic wave.

  6. Lunar Module Ascent Stage

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The Lunar Module 'Spider' ascent stage is photographed from the Command/Service Module on the fifth day of the Apollo 9 earth-orbital mission. The Lunar Module's descent stage had already been jettisoned.

  7. Ballasted photovoltaic module and module arrays

    DOEpatents

    Botkin, Jonathan; Graves, Simon; Danning, Matt

    2011-11-29

    A photovoltaic (PV) module assembly including a PV module and a ballast tray. The PV module includes a PV device and a frame. A PV laminate is assembled to the frame, and the frame includes an arm. The ballast tray is adapted for containing ballast and is removably associated with the PV module in a ballasting state where the tray is vertically under the PV laminate and vertically over the arm to impede overt displacement of the PV module. The PV module assembly can be installed to a flat commercial rooftop, with the PV module and the ballast tray both resting upon the rooftop. In some embodiments, the ballasting state includes corresponding surfaces of the arm and the tray being spaced from one another under normal (low or no wind) conditions, such that the frame is not continuously subjected to a weight of the tray.

  8. Module utilization committee

    NASA Technical Reports Server (NTRS)

    Volkmer, K.; Praver, G.

    1984-01-01

    Photovoltaic collector modules were declared surplus to the needs of the U.S. Dept. of Energy. The Module Utilization Committee was formed to make appropriate disposition of the surplus modules on a national basis and to act as a broker for requests for these modules originating outside of the National Photovoltaics Program.

  9. Automatic system to control the operation of an extended cavity diode laser

    NASA Astrophysics Data System (ADS)

    Allard, F.; Maksimovic, I.; Abgrall, M.; Laurent, Ph.

    2004-01-01

    This article describes an automatic system that permanently keeps an extended cavity diode laser (ECDL) frequency locked to a cesium line (852 nm). The ECDL has a new architecture based on an intracavity étalon. The laser power is 30 mW and the linewidth is narrower than 50 kHz. Two acousto-optic modulators finely change the laser frequency and optical power. The electronic control is composed of a computer, microcontrollers, digital analog converters, and direct digital synthesizers. The computer searches the ECDL parameters to tune it to the Cs line and closes the servoloop. It permanently checks the servoloop and relocks the laser if necessary. Both acousto-optic modulators are driven in real time by microcontrollers. They are programed in order to control the laser power and frequency with a predefined time sequence. This system, especially developed for an atomic fountain, can be easily adapted to a wide range of applications.

  10. A tunable line optical tweezers instrument with nanometer spatial resolution.

    PubMed

    Rogers, W Benjamin; Crocker, John C

    2014-04-01

    We describe a simple scanning-line optical tweezers instrument for measuring pair interactions between micrometer-sized colloidal particles. Our instrument combines a resonant scanning mirror and an acousto-optic modulator. The resonant scanning mirror creates a time-averaged line trap whose effective one-dimensional intensity profile, and corresponding trapping potential energy landscape can be programmed using the acousto-optic modulator. We demonstrate control over the confining potential by designing and measuring a family of one-dimensional harmonic traps. By adjusting the spring constant, we balance scattering-induced repulsive forces between a pair of trapped particles, creating a flat potential near contact that facilitates interaction measurements. We also develop a simple method for extracting the out-of-plane motion of trapped particles from their relative brightness, allowing us to resolve their relative separation to roughly 1 nm. PMID:24784615

  11. Almond brush module cutter

    SciTech Connect

    Zohns, M.A.; Jenkins, B.M.; Mehlschau, J.J.; Morrison, D.

    1983-06-01

    This paper addresses the design, construction, and evaluation of an almond brush module cutter. The module cutter is one link in a system which processes tree prunings for fuel and fiber. This system includes a modified cotton module builder, a module mover, the cutter, and a tub grinder. An economic analysis of the cutter is presented along with the problems involved in cutting brush modules.

  12. Modulational effects in accelerators

    SciTech Connect

    Satogata, T.

    1997-12-01

    We discuss effects of field modulations in accelerators, specifically those that can be used for operational beam diagnostics and beam halo control. In transverse beam dynamics, combined effects of nonlinear resonances and tune modulations influence diffusion rates with applied tune modulation has been demonstrated. In the longitudinal domain, applied RF phase and voltage modulations provide mechanisms for parasitic halo transport, useful in slow crystal extraction. Experimental experiences with transverse tune and RF modulations are also discussed.

  13. Actively Q-switched 2.9 μm Ho(3+)Pr(3+)-doped fluoride fiber laser.

    PubMed

    Hu, Tomonori; Hudson, Darren D; Jackson, Stuart D

    2012-06-01

    We report an efficient Q-switched Ho(3+)Pr(3+)-doped fluoride fiber laser, producing a peak power of 77 W, with pulse width of 78 ns. A slope efficiency of 20% with respect to the launched pump power was achieved. A TeO(2) acousto-optic modulator allowed continuous tunability of the pulse repetition frequency from 40 to 300 kHz. PMID:22660149

  14. Ring resonant cavities for spectroscopy

    DOEpatents

    Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.; Xie, Jinchun

    1999-01-01

    Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS).

  15. Acoustic Measurement of Surface Wave Damping by a Meniscus

    NASA Astrophysics Data System (ADS)

    Michel, Guillaume; Pétrélis, François; Fauve, Stéphan

    2016-04-01

    We investigate the reflection of gravity-capillary surface waves by a plane vertical barrier. The size of the meniscus is found to strongly affect reflection: the energy of the reflected wave with a pinned contact line is around twice the one corresponding to a fully developed meniscus. To perform these measurements, a new experimental setup similar to an acousto-optic modulator is developed and offers a simple way to measure the amplitude, frequency and direction of propagation of surface waves.

  16. Ring resonant cavities for spectroscopy

    DOEpatents

    Zare, R.N.; Martin, J.; Paldus, B.A.; Xie, J.

    1999-06-15

    Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS). 6 figs.

  17. The modulation of immunity

    SciTech Connect

    Mitchell, M.S.

    1985-01-01

    This book contains 13 chapters. Some of the chapter titles are: Modulation of Immunity by Thymus-Derived Lymphocytes; Modulation of Immunity by Macrophages; Modulation of Immunity by Soluble Mediators; Viruses and the Immune Response; and Methanol Extraction Residue: Effects and Mechanisms of Action.

  18. Temporal Aperture Modulation

    NASA Technical Reports Server (NTRS)

    Proctor, R. J.

    1981-01-01

    The two types of modulation techniques useful to X-ray imaging are reviewed. The use of optimum coded temporal aperature modulation is shown, in certain cases, to offer an advantage over a spatial aperture modulator. Example applications of a diffuse anisotropic X-ray background experiment and a wide field of view hard X-ray imager are discussed.

  19. Module flammability research

    NASA Astrophysics Data System (ADS)

    Sugimura, R. S.; Otth, D. H.; Arnett, J. C.; Lewis, K.

    1984-03-01

    The technology base required to construct fire-ratable modules is explored. New materials of construction and module configurations to achieve increased fire resistance are investigated. The fire-resistance capability of current PV module designs is assessed. Parametric tests are performed to characterize flammability.

  20. Integrating Module - NEMS Documentation

    EIA Publications

    2014-01-01

    Provides an overview of the complete National Energy Modeling System (NEMS) model, and includes brief descriptions of the modules with which the Integrating Module interacts. The emphasis and focus, however, is on the structure and function of the Integrating Module of NEMS.

  1. Modulating lignin in plants

    DOEpatents

    Apuya, Nestor; Bobzin, Steven Craig; Okamuro, Jack; Zhang, Ke

    2013-01-29

    Materials and methods for modulating (e.g., increasing or decreasing) lignin content in plants are disclosed. For example, nucleic acids encoding lignin-modulating polypeptides are disclosed as well as methods for using such nucleic acids to generate transgenic plants having a modulated lignin content.

  2. Rescue Manual. Module 5.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Instructional Materials Lab.

    This learner manual for rescuers covers the current techniques or practices required in the rescue service. The fifth of 10 modules contains information on hazardous materials. Key points, an introduction, and conclusion accompany substantive material in this module. In addition, the module contains a Department of Transportation guide chart on…

  3. Field Tests And Signature Analysis Of An Imaging CO2 Laser Radar

    NASA Astrophysics Data System (ADS)

    Wang, J. Y.; Bartholomew, B. J.; Streiff, M. L.; Starr, E. F.; Pruitt, P. A.

    1983-12-01

    A coherent, imaging CO2 laser radar has been built and tested in the field. This laser radar uses a single-waveguide CO2 laser and heterodyne detection. Two acousto-optic frequency shifters generate the IF frequency. An acousto-optic standing-wave device provides the 15 MHz intensity modulation used for ranging. The sensor includes a two-axis, dual-aperture galvonometer scanner with selectable field of view and depression angles. The optical system fits on an easily transportable 3 ft by 4 ft optical bench. Both reflectance and range images are produced. The range imagery analysis shows a range resolution of approximately one foot. Statistical analysis of the reflectance data from a military truck, the dirt ground, and an asphalt road shows that they are Rayleigh distributed. The reflectivities of these objects are determined to be around two percent through comparison with laboratory reflectometer measurements.

  4. Small modulation ellipsometry

    NASA Technical Reports Server (NTRS)

    Ducharme, Stephen P. (Inventor); El Hajj, Hassanayn M. (Inventor); Johs, Blaine D. (Inventor); Woollam, John A. (Inventor)

    1995-01-01

    In an ellipsometer, a phase-modulated, polarized light beam is applied to a sample, electrical signals are obtained representing the orthogonal planes of polarization of the light after it has interacted with the sample and the constants of the sample are calculated from the two resulting electrical signals. The phase modulation is sufficiently small so that the calibration errors are negligible. For this purpose, the phase modulator phase modulates the light within a range of no more than ten degrees modulations peak to peak. The two electrical signals are expanded by Fourier analysis and the coefficients thereof utilized to calculate psi and delta.

  5. Spatial Light Amplifier Modulators

    NASA Technical Reports Server (NTRS)

    Eng, Sverre T.; Olsson, N. Anders

    1992-01-01

    Spatial light amplifier modulators (SLAM's) are conceptual devices that effect two-dimensional spatial modulation in optical computing and communication systems. Unlike current spatial light modulators, these provide gain. Optical processors incorporating SLAM's designed to operate in reflection or transmission mode. Each element of planar SLAM array is optical amplifier - surface-emitting diode laser. Array addressed electrically with ac modulating signals superimposed on dc bias currents supplied to lasers. SLAM device provides both desired modulation and enough optical gain to enable splitting of output signal into many optical fibers without excessive loss of power.

  6. Loadable Hypervisor Modules

    SciTech Connect

    Naughton, III, Thomas J; Vallee, Geoffroy R; Scott, Stephen L; Aderholdt, Ferrol

    2010-01-01

    This paper discusses the implementation of a new hypervisor mechanism for loading dynamic shared objects (modules) at runtime. These loadable hypervisor modules (LHM) are modeled after the loadable kernel modules used in Linux. We detail the current LHM implementation based on the Xen hypervisor. Potential use cases for this LHM mechanism include dynamic hypervisor instrumentation for debug tracing or performance analysis. We discuss the initial LHM prototype and future plans.

  7. Cavity enhanced terahertz modulation

    SciTech Connect

    Born, N.; Scheller, M.; Moloney, J. V.; Koch, M.

    2014-03-10

    We present a versatile concept for all optical terahertz (THz) amplitude modulators based on a Fabry-Pérot semiconductor cavity design. Employing the high reflectivity of two parallel meta-surfaces allows for trapping selected THz photons within the cavity and thus only a weak optical modulation of the semiconductor absorbance is required to significantly damp the field within the cavity. The optical switching yields to modulation depths of more than 90% with insertion efficiencies of 80%.

  8. Bubble memory module

    NASA Technical Reports Server (NTRS)

    Bohning, O. D.; Becker, F. J.

    1980-01-01

    Design, fabrication and test of partially populated prototype recorder using 100 kilobit serial chips is described. Electrical interface, operating modes, and mechanical design of several module configurations are discussed. Fabrication and test of the module demonstrated the practicality of multiplexing resulting in lower power, weight, and volume. This effort resulted in the completion of a module consisting of a fully engineered printed circuit storage board populated with 5 of 8 possible cells and a wire wrapped electronics board. Interface of the module is 16 bits parallel at a maximum of 1.33 megabits per second data rate on either of two interface buses.

  9. Bracket for photovoltaic modules

    DOEpatents

    Ciasulli, John; Jones, Jason

    2014-06-24

    Brackets for photovoltaic ("PV") modules are described. In one embodiment, a saddle bracket has a mounting surface to support one or more PV modules over a tube, a gusset coupled to the mounting surface, and a mounting feature coupled to the gusset to couple to the tube. The gusset can have a first leg and a second leg extending at an angle relative to the mounting surface. Saddle brackets can be coupled to a torque tube at predetermined locations. PV modules can be coupled to the saddle brackets. The mounting feature can be coupled to the first gusset and configured to stand the one or more PV modules off the tube.

  10. Advanced module development overview

    NASA Technical Reports Server (NTRS)

    Smokler, M. I.

    1984-01-01

    Crystalline silicon solar power modules are examined for reliability and cost effectiveness. A goal of 12% solar energy conversion efficiency is considered feasible at a cost of 12/kWh, and a decision is made to limit consideration to float zone silicon wafer and dendritic web silicone modules. A preliminary module packaging configuration of glass/ethylene vinyl acetate/plastic film is selected. Anticipated module efficiency levels are 12.6% at 25 C and 11.5% at NOCT (Nominal Operating Cell Temperature).

  11. Silicon photonic heater-modulator

    DOEpatents

    Zortman, William A.; Trotter, Douglas Chandler; Watts, Michael R.

    2015-07-14

    Photonic modulators, methods of forming photonic modulators and methods of modulating an input optical signal are provided. A photonic modulator includes a disk resonator having a central axis extending along a thickness direction of the disk resonator. The disk resonator includes a modulator portion and a heater portion. The modulator portion extends in an arc around the central axis. A PN junction of the modulator portion is substantially normal to the central axis.

  12. Human Development Student Modules.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This set of 61 student learning modules deals with various topics pertaining to human development. The modules, which are designed for use in performance-based vocational education programs, each contain the following components: an introduction for the student, a performance objective, a variety of learning activities, content information, a…

  13. Cosmetology. Computerized Learning Modules.

    ERIC Educational Resources Information Center

    Finnerty, Kathy, Ed.

    Intended to help reading-limited students meet course objectives, these 11 modules are based on instructional materials in cosmetology that have a higher readability equivalent. Modules cover bacteriology, chemical waving, scalp and hair massage, chemistry, hair shaping, hairstyling, chemical hair relaxing, hair coloring, skin and scalp,…

  14. Module Safety Issues (Presentation)

    SciTech Connect

    Wohlgemuth, J.

    2012-02-01

    Description of how to make PV modules so that they are less likely to turn into safety hazards. Making modules inherently safer with minimum additional cost is the preferred approach for PV. Safety starts with module design to ensure redundancy within the electrical circuitry to minimize open circuits and proper mounting instructions to prevent installation related ground faults. Module manufacturers must control the raw materials and processes to ensure that that every module is built like those qualified through the safety tests. This is the reason behind the QA task force effort to develop a 'Guideline for PV Module Manufacturing QA'. Periodic accelerated stress testing of production products is critical to validate the safety of the product. Combining safer PV modules with better systems designs is the ultimate goal. This should be especially true for PV arrays on buildings. Use of lower voltage dc circuits - AC modules, DC-DC converters. Use of arc detectors and interrupters to detect arcs and open the circuits to extinguish the arcs.

  15. Logs Perl Module

    2007-04-04

    A perl module designed to read and parse the voluminous set of event or accounting log files produced by a Portable Batch System (PBS) server. This module can filter on date-time and/or record type. The data can be returned in a variety of formats.

  16. Applied Algebra Curriculum Modules.

    ERIC Educational Resources Information Center

    Texas State Technical Coll., Marshall.

    This collection of 11 applied algebra curriculum modules can be used independently as supplemental modules for an existing algebra curriculum. They represent diverse curriculum styles that should stimulate the teacher's creativity to adapt them to other algebra concepts. The selected topics have been determined to be those most needed by students…

  17. Membrane module assembly

    DOEpatents

    Kaschemekat, Jurgen

    1994-01-01

    A membrane module assembly adapted to provide a flow path for the incoming feed stream that forces it into prolonged heat-exchanging contact with a heating or cooling mechanism. Membrane separation processes employing the module assembly are also disclosed. The assembly is particularly useful for gas separation or pervaporation.

  18. Membrane module assembly

    DOEpatents

    Kaschemekat, J.

    1994-03-15

    A membrane module assembly is described which is adapted to provide a flow path for the incoming feed stream that forces it into prolonged heat-exchanging contact with a heating or cooling mechanism. Membrane separation processes employing the module assembly are also disclosed. The assembly is particularly useful for gas separation or pervaporation. 2 figures.

  19. Nonformal Education Training Module.

    ERIC Educational Resources Information Center

    Fox, Helen; And Others

    This Peace Corps Nonformal Education (NFE) training module provides training ideas for volunteers. This module contains 10 sessions, each designed to fit into a 3-hour period: (1) What is NFE? (2) adult learning; (3) helping people identify their needs; (4) facilitation skills--part 1; (5) facilitation skills--part 2; (6) NFE materials…

  20. Solar energy modulator

    NASA Technical Reports Server (NTRS)

    Hale, R. R. (Inventor); Mcdougal, A. R.

    1984-01-01

    A module is described with a receiver having a solar energy acceptance opening and supported by a mounting ring along the optic axis of a parabolic mirror in coaxial alignment for receiving solar energy from the mirror, and a solar flux modulator plate for varying the quantity of solar energy flux received by the acceptance opening of the module. The modulator plate is characterized by an annular, plate-like body, the internal diameter of which is equal to or slightly greater than the diameter of the solar energy acceptance opening of the receiver. Slave cylinders are connected to the modulator plate for supporting the plate for axial displacement along the axis of the mirror, therby shading the opening with respect to solar energy flux reflected from the surface of the mirror to the solar energy acceptance opening.

  1. Japanese Experiment Module (JEM)

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Japanese Experiment Module (JEM) pressure module is removed from its shipping crate and moved across the floor of the Space Station Processing Facility at Kennedy Space Center (KSC) to a work stand. A research laboratory, the pressurized module is the first element of the JEM, named 'Kibo' (Hope) to arrive at KSC. Japan's primary contribution to the International Space Station, the module will enhance unique research capabilities of the orbiting complex by providing an additional environment in which astronauts will conduct experiments. The JEM also includes an exposed facility or platform for space environment experiments, a robotic manipulator system, and two logistics modules. The various JEM components will be assembled in space over the course of three Shuttle missions.

  2. A multipurpose digital modulator

    NASA Technical Reports Server (NTRS)

    Davarian, Faramaz; Sumida, Joe T.

    1989-01-01

    The theoretical basis and hardware implementation of a versatile device which uses digital signal-processing methods to achieve signal modulation are reported. The carrier-modulation process is formulated as a simple quadrature equation; a generalized description of the signal constellation to be processed is derived; the pulse-shaping scheme is explained; and the system architecture is described in detail and illustrated with diagrams. Experimental results obtained with a breadboard transmitter based on this modulation technique are presented in extensive graphs. The power spectra and eye diagrams generated for different QPSK, 8PSK, and MSK modulation schemes are shown to be in good agreement with theoretical predictions. It is suggested that this modulator could be readily implemented in VLSI and mass produced.

  3. Photovoltaic module and interlocked stack of photovoltaic modules

    DOEpatents

    Wares, Brian S.

    2014-09-02

    One embodiment relates to an arrangement of photovoltaic modules configured for transportation. The arrangement includes a plurality of photovoltaic modules, each photovoltaic module including a frame. A plurality of individual male alignment features and a plurality of individual female alignment features are included on each frame. Adjacent photovoltaic modules are interlocked by multiple individual male alignment features on a first module of the adjacent photovoltaic modules fitting into and being surrounded by corresponding individual female alignment features on a second module of the adjacent photovoltaic modules. Other embodiments, features and aspects are also disclosed.

  4. Optical modulator system

    NASA Technical Reports Server (NTRS)

    Brand, J.

    1972-01-01

    The fabrication, test, and delivery of an optical modulator system which will operate with a mode-locked Nd:YAG laser indicating at either 1.06 or 0.53 micrometers is discussed. The delivered hardware operates at data rates up to 400 Mbps and includes a 0.53 micrometer electrooptic modulator, a 1.06 micrometer electrooptic modulator with power supply and signal processing electronics with power supply. The modulators contain solid state drivers which accept digital signals with MECL logic levels, temperature controllers to maintain a stable thermal environment for the modulator crystals, and automatic electronic compensation to maximize the extinction ratio. The modulators use two lithium tantalate crystals cascaded in a double pass configuration. The signal processing electronics include encoding electronics which are capable of digitizing analog signals between the limit of + or - 0.75 volts at a maximum rate of 80 megasamples per second with 5 bit resolution. The digital samples are serialized and made available as a 400 Mbps serial NRZ data source for the modulators. A pseudorandom (PN) generator is also included in the signal processing electronics. This data source generates PN sequences with lengths between 31 bits and 32,767 bits in a serial NRZ format at rates up to 400 Mbps.

  5. Amplitude Modulator Chassis

    SciTech Connect

    Erbert, G

    2009-09-01

    The Amplitude Modulator Chassis (AMC) is the final component in the MOR system and connects directly to the PAM input through a 100-meter fiber. The 48 AMCs temporally shape the 48 outputs of the MOR using an arbitrary waveform generator coupled to an amplitude modulator. The amplitude modulation element is a two stage, Lithium Niobate waveguide device, where the intensity of the light passing through the device is a function of the electrical drive applied. The first stage of the modulator is connected to a programmable high performance Arbitrary Waveform Generator (AWG) consisting of 140 impulse generators space 250 ps apart. An arbitrary waveform is generated by independently varying the amplitude of each impulse generator and then summing the impulses together. In addition to the AWG a short pulse generator is also connected to the first stage of the modulator to provide a sub 100-ps pulse used for timing experiments. The second stage of the modulator is connect to a square pulse generator used to further attenuate any pre or post pulse light passing through the first stage of the modulator. The fast rise and fall time of the square pulse generator is also used to produce fast rise and fall times of the AWG by clipping the AWG pulse. For maximum extinction, a pulse bias voltage is applied to each stage of the modulator. A pulse voltage is applied as opposed to a DC voltage to prevent charge buildup on the modulator. Each bias voltage is adjustable to provide a minimum of 50-dB extinction. The AMC is controlled through ICCS to generate the desired temporal pulse shape. This process involves a closed-loop control algorithm, which compares the desired temporal waveform to the produced optical pulse, and iterates the programming of the AWG until the two waveforms agree within an allowable tolerance.

  6. Water heater control module

    DOEpatents

    Hammerstrom, Donald J

    2013-11-26

    An advanced electric water heater control system that interfaces with a high temperature cut-off thermostat and an upper regulating thermostat. The system includes a control module that is electrically connected to the high-temperature cut-off thermostat and the upper regulating thermostat. The control module includes a switch to open or close the high-temperature cut-off thermostat and the upper regulating thermostat. The control module further includes circuitry configured to control said switch in response to a signal selected from the group of an autonomous signal, a communicated signal, and combinations thereof.

  7. DOT Transmit Module

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Gin, Jonathan W.; Sahasrabudhe, Adit; Patawaran, Ferze D.; Nguyen, Danh H.; Nguyen, Huy

    2013-01-01

    The Deep Space Optical Terminal (DOT) transmit module demonstrates the DOT downlink signaling in a flight electronics assembly that can be qualified for deep space. The assembly has the capability to generate an electronic pulse-position modulation (PPM) waveform suitable for driving a laser assembly to produce the optical downlink signal. The downlink data enters the assembly through a serializer/ deserializer (SERDES) interface, and is encoded using a serially concatenated PPM (SCPPM) forward error correction code. The encoded data is modulated using PPM with an inter-symbol guard time to aid in receiver synchronization. Monitor and control of the assembly is via a low-voltage differential signal (LVDS) interface

  8. Optical modulator including grapene

    DOEpatents

    Liu, Ming; Yin, Xiaobo; Zhang, Xiang

    2016-06-07

    The present invention provides for a one or more layer graphene optical modulator. In a first exemplary embodiment the optical modulator includes an optical waveguide, a nanoscale oxide spacer adjacent to a working region of the waveguide, and a monolayer graphene sheet adjacent to the spacer. In a second exemplary embodiment, the optical modulator includes at least one pair of active media, where the pair includes an oxide spacer, a first monolayer graphene sheet adjacent to a first side of the spacer, and a second monolayer graphene sheet adjacent to a second side of the spacer, and at least one optical waveguide adjacent to the pair.

  9. Modulated curvaton decay

    SciTech Connect

    Assadullahi, Hooshyar; Wands, David; Firouzjahi, Hassan; Namjoo, Mohammad Hossein E-mail: firouz@mail.ipm.ir E-mail: david.wands@port.ac.uk

    2013-03-01

    We study primordial density perturbations generated by the late decay of a curvaton field whose decay rate may be modulated by the local value of another isocurvature field, analogous to models of modulated reheating at the end of inflation. We calculate the primordial density perturbation and its local-type non-Gaussianity using the sudden-decay approximation for the curvaton field, recovering standard curvaton and modulated reheating results as limiting cases. We verify the Suyama-Yamaguchi inequality between bispectrum and trispectrum parameters for the primordial density field generated by multiple field fluctuations, and find conditions for the bound to be saturated.

  10. Sonication standard laboratory module

    DOEpatents

    Beugelsdijk, Tony; Hollen, Robert M.; Erkkila, Tracy H.; Bronisz, Lawrence E.; Roybal, Jeffrey E.; Clark, Michael Leon

    1999-01-01

    A standard laboratory module for automatically producing a solution of cominants from a soil sample. A sonication tip agitates a solution containing the soil sample in a beaker while a stepper motor rotates the sample. An aspirator tube, connected to a vacuum, draws the upper layer of solution from the beaker through a filter and into another beaker. This beaker can thereafter be removed for analysis of the solution. The standard laboratory module encloses an embedded controller providing process control, status feedback information and maintenance procedures for the equipment and operations within the standard laboratory module.

  11. Module systems applied to biomass

    SciTech Connect

    Jenkins, B.M.

    1983-12-01

    Applications of cotton moduling equipment to biomass have been tested in California. A module of chopped rice straw was made to determine physical characteristics of straw modules. A module system for tree prunings using a heavy duty module builder was tested extensively in 1983. Total direct costs to module, transport 8 km (5 mi), store, cut, tubgrind, and haul chips 50 km (30 mi) to a cogeneration plant is estimated to be $26.64/t ($24.17/t).

  12. Production, preparation, and performance of shaped ultrafast laser pulses

    NASA Astrophysics Data System (ADS)

    Davis, Jennifer Case

    1999-09-01

    In the following pages, the current state-of-the art in the method and implementation of acousto-optic modulator (AOM) ultrafast laser pulse shaping is discussed. Since ultrafast laser technologies are relatively recent, many aspects of these pulses and their interaction with material systems (and in particular, optically dense systems) have yet to be well- characterized. Here, we make some headway in understanding the interaction between intense, shaped ultrafast pulses and optically dense media via computer simulations in which the Maxwell-Bloch coupled equations are solved numerically using a recursive algorithm. In one set of experiments, we studied the propagation of shaped ultrafast laser pulses through a cell filled with an optically dense sample of rubidium vapor. We soon found that the excited state dynamics in atomic rubidium change non-intuitively as different pulse shapes are applied. In this case, characterization of the excited state dynamics is important for illuminating the mechanisms involved in the commercial preparation of the spin-polarized noble gases used in MRI lung studies. Thus, theoretical modeling of the laser- material interaction via the Maxwell-Bloch coupled equations allows us to predict the interaction effects on both the material system and the propagating laser pulses. In other experiments we show (via computer simulations) that a series of shaped Raman pulses can excite arbitrary vibrational transitions in homonuclear diatomics. In these calculations, a blue-to-red frequency-swept (off- resonant) pump pulse and a red-to-blue Stokes pulse are employed to sequentially excite Δ v = 1 vibrational transitions in an anharmonic potential. Use of increasingly complicated models shows that despite rotational effects, such a pulse sequence should be effective in exciting certain diatomics into high vibrational states. Since highly (vibrationally) excited oxygen is a critical reagent in upper atmosphere energy transfer reactions with

  13. A Polarization-Diversity Homodyne Image-Reject Optical Tranceiver Architecture for Improved Range and Signal Detection in Coherent Doppler Lidars

    NASA Astrophysics Data System (ADS)

    Abari, C. F.; Chu, X.; Mann, J.

    2014-12-01

    Doppler light detection and ranging (lidar) has been used for a few decades for the characterization of wind fields and turbulence structures in the atmosphere. More recently, due to the advances in fiber optic communications, all-fiber coherent Doppler lidars (CDL) have been developed and widely used as a primary instrument for probing the atmospheric boundary layer wind fields. Due to a variety of reasons, all-fiber CDLs have gradually replaced their counterparts benefiting from technologies other than fiber optics. Most CDLs suffer from a number of drawbacks inherent to their principle of operation. For instance, one of the main challenges in CDLs is extracting the signal information from noisy observations, which is common to most opto-electronic systems. Moreover, it is sometimes challenging to extract the sign of the measured radial velocity. Conventionally, CDLs have benefitted from an intermediate frequency (IF) heterodyne receiver architecture for the determination of the radial velocity. In such systems, either the transmitted or the local oscillator (LO) signal is shifted in frequency. Such architectures may suffer from increased noise and spurious effects due to the employment of additional active components, e.g., acousto-optic modulator (AOM), limited measurement bandwidth (BW), and a more sophisticated electronic front-end for signal detection. On the other hand, one of the main challenges in long-range (pulsed) CDLs is the limitations imposed on the pulse repetition rate (PRR) as well as the available transmit power. These restrictions are more significant in all-fiber pulsed CDLs in which Erbium doped fiber amplifiers (EDFA) are employed for the amplification of the optical pulses. In this study, we propose an alternative reconfigurable opto-electronic front-end transceiver architecture in all-fiber CDLs where there is no compromise in the detection BW. Additionally, by benefiting from a polarization diversity architecture we show that both the PRR

  14. Open Path Trace Gas Laser Sensors for UAV Deployment

    NASA Astrophysics Data System (ADS)

    Shadman, S.; Mchale, L.; Rose, C.; Yalin, A.

    2015-12-01

    Novel trace gas sensors based on open-path Cavity Ring-down Spectroscopy (CRDS) are being developed to enable remote and mobile deployments including on small unmanned aerial systems (UAS). Relative to established closed-path CRDS instruments, the use of open-path configurations allows removal of the bulky and power hungry vacuum and flow system, potentially enabling lightweight and low power instruments with high sensitivity. However, open path operation introduces new challenges including the need to maintain mirror cleanliness, mitigation of particle optical effects, and the need to measure spectral features that are relatively broad. The present submission details open-path CRDS instruments for ammonia and methane and their planned use in UAS studies. The ammonia sensor uses a quantum cascade laser at 10.3 mm in a configuration in which the laser frequency is continuously swept and a trigger circuit and acousto-optic modulator (AOM) extinguish the light when the laser is resonant with the cavity. Ring-down signals are measured with a two-stage thermoelectrically cooled MCT photodetector. The cavity mirrors have reflectivity of 0.9995 and a noise equivalent absorption of 1.5 ppb Hz-1/2 was demonstrated. A first version of the methane sensor operated at 1.7um with a telecom diode laser while the current version operates at 3.6 um with an interband cascade laser (stronger absorption). We have performed validation measurements against known standards for both sensors. Compact optical assemblies are being developed for UAS deployment. For example, the methane sensor head will have target mass of <4 kg and power draw <40 W. A compact single board computer and DAQ system is being designed for sensor control and signal processing with target mass <1 kg and power draw <10 W. The sensor size and power parameters are suitable for UAS deployment on both fixed wing and rotor style UAS. We plan to deploy the methane sensor to measure leakage and emission of methane from

  15. Narrow-linewidth Q-switched random distributed feedback fiber laser.

    PubMed

    Xu, Jiangming; Ye, Jun; Xiao, Hu; Leng, Jinyong; Wu, Jian; Zhang, Hanwei; Zhou, Pu

    2016-08-22

    A narrow-linewidth Q-switched random fiber laser (RFL) based on a half-opened cavity, which is realized by narrow-linewidth fiber Bragg grating (FBG) and a section of 3 km passive fiber, has been proposed and experimentally investigated. The narrow-linewidth lasing is generated by the spectral filtering of three FBGs with linewidth of 1.21 nm, 0.56 nm, and 0.12 nm, respectively. The Q switching of the distributed cavity is achieved by placing an acousto-optical modulator (AOM) between the FBG and the passive fiber. The maximal output powers of the narrow-linewidth RFLs with the three different FBGs are 0.54 W, 0.27 W, and 0.08 W, respectively. Furthermore, the repetition rates of the output pulses are 500 kHz, and the pulse durations are about 500 ns. The corresponding pulse energies are about 1.08 μJ, 0.54 μJ, and 0.16 μJ, accordingly. The linewidth of FBG can influence the output characteristics in full scale. The narrower the FBG, the higher the pump threshold; the lower the output power at the same pump level, the more serious the linewidth broadening; and thus the higher the proportion of the CW-ground exists in the output pulse trains. Thanks to the assistance of the band-pass filter (BPF), the proportion of the CW-ground of narrow-linewidth Q-switched RFL under the relative high-pump-low-output condition can be reduced effectively. The experimental results indicate that it is challenging to demonstrate a narrow-linewidth Q-switched RFL with high quality output. But further power scaling and linewidth narrowing is possible in the case of operating parameters, optimization efforts, and a more powerful pump source. To the best of our knowledge, this is the first demonstration of narrow-linewidth generation in a Q-switched RFL. PMID:27557200

  16. Digital optical conversion module

    DOEpatents

    Kotter, Dale K.; Rankin, Richard A.

    1991-02-26

    A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer.

  17. Digital optical conversion module

    DOEpatents

    Kotter, D.K.; Rankin, R.A.

    1988-07-19

    A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer. 2 figs.

  18. GREET Pretreatment Module

    SciTech Connect

    Adom, Felix K.; Dunn, Jennifer B.; Han, Jeongwoo

    2014-09-01

    A wide range of biofuels and biochemicals can be produced from biomass via different pretreatment technologies that yield sugars. This report documents the material and energy flows that occur when fermentable sugars from four lignocellulosic feedstocks (corn stover, miscanthus, switchgrass, and poplar) are produced via dilute acid pretreatment and ammonia fiber expansion. These flows are documented for inclusion in the pretreatment module of the Greenhouses Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model. Process simulations of each pretreatment technology were developed in Aspen Plus. Material and energy consumption data from Aspen Plus were then compiled in the GREET pretreatment module. The module estimates the cradle-to-gate fossil energy consumption (FEC) and greenhouse gas (GHG) emissions associated with producing fermentable sugars. This report documents the data and methodology used to develop this module and the cradle-to-gate FEC and GHG emissions that result from producing fermentable sugars.

  19. TRANSIMS environmental module

    SciTech Connect

    Williams, M.D.; Thayer, G.R.; Brown, M.J.

    1996-09-01

    The purpose of the environmental module is to translate traveler behavior into consequent air quality, energy consumption, watershed nitrate deposition, and carbon dioxide emissions. The TRANSIMS environmental module is composed of a system of environmental modules which can describe both the average conditions and the fluctuations about the averages. It uses a prognostic meteorological model, HOTMAC, to describe the atmospheric conditions. The environmental module will use modal emissions models to define the emissions. Transport and dispersion of conservative pollutants will be described with a Monte-Carlo Kernel model (RAPTAD). Air chemistry will be described by an airshed model with the current choice being the CIT model developed at the California Institute of Technology and the Carnegie Mellon Institute of Technology.

  20. Module encapsulation technology

    NASA Technical Reports Server (NTRS)

    Willis, P.

    1986-01-01

    The identification and development techniques for low-cost module encapsulation materials were reviewed. Test results were displayed for a variety of materials. The improved prospects for modeling encapsulation systems for life prediction were reported.

  1. Digital optical conversion module

    NASA Astrophysics Data System (ADS)

    Kotter, Dale K.; Rankin, Richard A.

    1988-07-01

    A digital optical conversion module is used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer.

  2. Basic memory module

    NASA Technical Reports Server (NTRS)

    Tietze, F. C.

    1974-01-01

    Construction and electrical characterization of the 4096 x 2-bit Basic Memory Module (BMM) are reported for the Space Ultrareliable Modular Computer (SUMC) program. The module uses four 2K x 1-bit N-channel FET, random access memory chips, called array chips, and two sense amplifier chips, mounted and interconnected on a ceramic substrate. Four 5% tolerance power supplies are required. At the Module, the address, chip select, and array select lines require a 0-8.5 V MOS signal level. The data output, read-strobe, and write-enable lines operate at TTl levels. Although the module is organized as 4096 x 2 bits, it can be used in a 8196 x 1-bit application with appropriate external connections. A 4096 x 1-bit organization can be obtained by depopulating chips.

  3. Lunar robotic maintenance module

    NASA Technical Reports Server (NTRS)

    Ayres, Michael L.

    1988-01-01

    A design for a robotic maintenance module that will assist a mobile 100-meter lunar drill is introduced. The design considers the following areas of interest: the atmospheric conditions, actuator systems, power supply, material selection, weight, cooling system and operation.

  4. Autonomous Module Builder

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conventional cotton harvesting requires many seasonal laborers. To reduce labor requirements, equipment manufacturers have recently introduced harvesters with on-board module building capabilities; however, this feature is only available on pickers and these machines are expensive. Conventional mo...

  5. Firefighting module development

    NASA Technical Reports Server (NTRS)

    Burns, R. A.

    1981-01-01

    The firefighting module is a lightweight, compact, self contained, helicopter-transportable unit for fighting harbor and other specialty fires as well as for use in emergency water pumping applications. Units were fabricated and tested. A production type unit is undergoing an inservice evaluation and demonstration program at the port of St Louis. The primary purpose is to promote enhanced harbor fire protection at inland and coastal ports. The module and its development are described.

  6. Module two: energy utilization

    SciTech Connect

    Not Available

    1980-01-01

    This report contains a teaching module for presentation at the junior college level. A shortened version can also be presented to civic groups or high school vocational classes. Energy use in the past is contrasted with present energy use in 3 sectors: business, industry and the home. The module explains specifically the changes in energy sources and outlines energy use, the need for, and methods of conservation of energy in these 3 sections. 29 references, 7 figures. (DMC)

  7. Photovoltaic module reliability workshop

    NASA Astrophysics Data System (ADS)

    Mrig, L.

    The paper and presentations compiled in this volume form the Proceedings of the fourth in a series of Workshops sponsored by Solar Energy Research Institute (SERI/DOE) under the general theme of photovoltaic module reliability during the period 1986 to 1990. The reliability photovoltaic (PV) modules/systems is exceedingly important along with the initial cost and efficiency of modules if the PV technology has to make a major impact in the power generation market, and for it to compete with the conventional electricity producing technologies. The reliability of photovoltaic modules has progressed significantly in the last few years as evidenced by warrantees available on commercial modules of as long as 12 years. However, there is still need for substantial research and testing required to improve module field reliability to levels of 30 years or more. Several small groups of researchers are involved in this research, development, and monitoring activity around the world. In the U.S., PV manufacturers, DOE laboratories, electric utilities and others are engaged in the photovoltaic reliability research and testing. This group of researchers and others interested in this field were brought together under SERI/DOE sponsorship to exchange the technical knowledge and field experience as related to current information in this important field. The papers presented here reflect this effort.

  8. Directed network modules

    NASA Astrophysics Data System (ADS)

    Palla, Gergely; Farkas, Illés J.; Pollner, Péter; Derényi, Imre; Vicsek, Tamás

    2007-06-01

    A search technique locating network modules, i.e. internally densely connected groups of nodes in directed networks is introduced by extending the clique percolation method originally proposed for undirected networks. After giving a suitable definition for directed modules we investigate their percolation transition in the Erdos Rényi graph both analytically and numerically. We also analyse four real-world directed networks, including Google's own web-pages, an email network, a word association graph and the transcriptional regulatory network of the yeast Saccharomyces cerevisiae. The obtained directed modules are validated by additional information available for the nodes. We find that directed modules of real-world graphs inherently overlap and the investigated networks can be classified into two major groups in terms of the overlaps between the modules. Accordingly, in the word-association network and Google's web-pages, overlaps are likely to contain in-hubs, whereas the modules in the email and transcriptional regulatory network tend to overlap via out-hubs.

  9. Photovoltaic module reliability workshop

    SciTech Connect

    Mrig, L.

    1990-01-01

    The paper and presentations compiled in this volume form the Proceedings of the fourth in a series of Workshops sponsored by Solar Energy Research Institute (SERI/DOE) under the general theme of photovoltaic module reliability during the period 1986--1990. The reliability Photo Voltaic (PV) modules/systems is exceedingly important along with the initial cost and efficiency of modules if the PV technology has to make a major impact in the power generation market, and for it to compete with the conventional electricity producing technologies. The reliability of photovoltaic modules has progressed significantly in the last few years as evidenced by warranties available on commercial modules of as long as 12 years. However, there is still need for substantial research and testing required to improve module field reliability to levels of 30 years or more. Several small groups of researchers are involved in this research, development, and monitoring activity around the world. In the US, PV manufacturers, DOE laboratories, electric utilities and others are engaged in the photovoltaic reliability research and testing. This group of researchers and others interested in this field were brought together under SERI/DOE sponsorship to exchange the technical knowledge and field experience as related to current information in this important field. The papers presented here reflect this effort.

  10. Apollo 9 Command/Service Modules photographed from Lunar Module

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The Apollo 9 Command/Service Modules photographed from the Lunar Module, 'Spider', on the fifth day of the Apollo 9 earth-orbital mission. Docking mechanism is visible in nose of the Command Module, 'Gumdrop'. Object jutting out from the Service Module aft bulkhead is the high-gain S-Band antenna.

  11. "Smart" Sensor Module

    NASA Technical Reports Server (NTRS)

    Mahajan, Ajay

    2007-01-01

    An assembly that contains a sensor, sensor-signal-conditioning circuitry, a sensor-readout analog-to-digital converter (ADC), data-storage circuitry, and a microprocessor that runs special-purpose software and communicates with one or more external computer(s) has been developed as a prototype of "smart" sensor modules for monitoring the integrity and functionality (the "health") of engineering systems. Although these modules are now being designed specifically for use on rocket-engine test stands, it is anticipated that they could also readily be designed to be incorporated into health-monitoring subsystems of such diverse engineering systems as spacecraft, aircraft, land vehicles, bridges, buildings, power plants, oilrigs, and defense installations. The figure is a simplified block diagram of the "smart" sensor module. The analog sensor readout signal is processed by the ADC, the digital output of which is fed to the microprocessor. By means of a standard RS-232 cable, the microprocessor is connected to a local personal computer (PC), from which software is downloaded into a randomaccess memory in the microprocessor. The local PC is also used to debug the software. Once the software is running, the local PC is disconnected and the module is controlled by, and all output data from the module are collected by, a remote PC via an Ethernet bus. Several smart sensor modules like this one could be connected to the same Ethernet bus and controlled by the single remote PC. The software running in the microprocessor includes driver programs for operation of the sensor, programs that implement self-assessment algorithms, programs that implement protocols for communication with the external computer( s), and programs that implement evolutionary methodologies to enable the module to improve its performance over time. The design of the module and of the health-monitoring system of which it is a part reflects the understanding that the main purpose of a health

  12. Universal enveloping crossed module of Leibniz crossed modules and representations

    NASA Astrophysics Data System (ADS)

    Casado, Rafael F.; García-Martínez, Xabier; Ladra, Manuel

    2016-03-01

    The universal enveloping algebra functor UL: Lb → Alg, defined by Loday and Pirashvili [1], is extended to crossed modules. Then we construct an isomorphism between the category of representations of a Leibniz crossed module and the category of left modules over its universal enveloping crossed module of algebras. Note that the procedure followed in the proof for the Lie case cannot be adapted, since the actor in the category of Leibniz crossed modules does not always exist.

  13. Strictly homogeneous laterally complete modules

    NASA Astrophysics Data System (ADS)

    Chilin, V. I.; Karimov, J. A.

    2016-03-01

    Let A be a laterally complete commutative regular algebra and X be a laterally complete A-module. In this paper we introduce a notion of homogeneous and strictly homogeneous A-modules. It is proved that any homogeneous A-module is strictly homogeneous A-module, if the Boolean algebra of all idempotents in A is multi-σ-finite.

  14. Intensity modulated proton therapy.

    PubMed

    Kooy, H M; Grassberger, C

    2015-07-01

    Intensity modulated proton therapy (IMPT) implies the electromagnetic spatial control of well-circumscribed "pencil beams" of protons of variable energy and intensity. Proton pencil beams take advantage of the charged-particle Bragg peak-the characteristic peak of dose at the end of range-combined with the modulation of pencil beam variables to create target-local modulations in dose that achieves the dose objectives. IMPT improves on X-ray intensity modulated beams (intensity modulated radiotherapy or volumetric modulated arc therapy) with dose modulation along the beam axis as well as lateral, in-field, dose modulation. The clinical practice of IMPT further improves the healthy tissue vs target dose differential in comparison with X-rays and thus allows increased target dose with dose reduction elsewhere. In addition, heavy-charged-particle beams allow for the modulation of biological effects, which is of active interest in combination with dose "painting" within a target. The clinical utilization of IMPT is actively pursued but technical, physical and clinical questions remain. Technical questions pertain to control processes for manipulating pencil beams from the creation of the proton beam to delivery within the patient within the accuracy requirement. Physical questions pertain to the interplay between the proton penetration and variations between planned and actual patient anatomical representation and the intrinsic uncertainty in tissue stopping powers (the measure of energy loss per unit distance). Clinical questions remain concerning the impact and management of the technical and physical questions within the context of the daily treatment delivery, the clinical benefit of IMPT and the biological response differential compared with X-rays against which clinical benefit will be judged. It is expected that IMPT will replace other modes of proton field delivery. Proton radiotherapy, since its first practice 50 years ago, always required the highest level of

  15. Intensity modulated proton therapy

    PubMed Central

    Grassberger, C

    2015-01-01

    Intensity modulated proton therapy (IMPT) implies the electromagnetic spatial control of well-circumscribed “pencil beams” of protons of variable energy and intensity. Proton pencil beams take advantage of the charged-particle Bragg peak—the characteristic peak of dose at the end of range—combined with the modulation of pencil beam variables to create target-local modulations in dose that achieves the dose objectives. IMPT improves on X-ray intensity modulated beams (intensity modulated radiotherapy or volumetric modulated arc therapy) with dose modulation along the beam axis as well as lateral, in-field, dose modulation. The clinical practice of IMPT further improves the healthy tissue vs target dose differential in comparison with X-rays and thus allows increased target dose with dose reduction elsewhere. In addition, heavy-charged-particle beams allow for the modulation of biological effects, which is of active interest in combination with dose “painting” within a target. The clinical utilization of IMPT is actively pursued but technical, physical and clinical questions remain. Technical questions pertain to control processes for manipulating pencil beams from the creation of the proton beam to delivery within the patient within the accuracy requirement. Physical questions pertain to the interplay between the proton penetration and variations between planned and actual patient anatomical representation and the intrinsic uncertainty in tissue stopping powers (the measure of energy loss per unit distance). Clinical questions remain concerning the impact and management of the technical and physical questions within the context of the daily treatment delivery, the clinical benefit of IMPT and the biological response differential compared with X-rays against which clinical benefit will be judged. It is expected that IMPT will replace other modes of proton field delivery. Proton radiotherapy, since its first practice 50 years ago, always required the

  16. Bunch identification module

    SciTech Connect

    Fox, J.D.

    1981-01-01

    This module provides bunch identification and timing signals for the PEP Interaction areas. Timing information is referenced to the PEP master oscillator, and adjusted in phase as a function of region. Identification signals are generated in a manner that allows observers in all interaction regions to agree on an unambiguous bunch identity. The module provides bunch identification signals via NIM level logic, upon CAMAC command, and through LED indicators. A front panel ''region select'' switch allows the same module to be used in all regions. The module has two modes of operation: a bunch identification mode and a calibration mode. In the identification mode, signals indicate which of the three bunches of electrons and positrons are interacting, and timing information about beam crossing is provided. The calibration mode is provided to assist experimenters making time of flight measurements. In the calibration mode, three distinct gating signals are referenced to a selected bunch, allowing three timing systems to be calibrated against a common standard. Physically, the bunch identifier is constructed as a single width CAMAC module. 2 figs., 1 tab.

  17. NREL module energy rating methodology

    SciTech Connect

    Whitaker, C.; Newmiller, J.; Kroposki, B.

    1995-11-01

    The goals of this project were to develop a tool for: evaluating one module in different climates; comparing different modules; provide a Q&D method for estimating periodic energy production; provide an achievable module rating; provide an incentive for manufacturers to optimize modules to non-STC conditions; and to have a consensus-based, NREL-sponsored activity. The approach taken was to simulate module energy for five reference days of various weather conditions. A performance model was developed.

  18. Deep frequency modulation interferometry.

    PubMed

    Gerberding, Oliver

    2015-06-01

    Laser interferometry with pm/Hz precision and multi-fringe dynamic range at low frequencies is a core technology to measure the motion of various objects (test masses) in space and ground based experiments for gravitational wave detection and geodesy. Even though available interferometer schemes are well understood, their construction remains complex, often involving, for example, the need to build quasi-monolithic optical benches with dozens of components. In recent years techniques have been investigated that aim to reduce this complexity by combining phase modulation techniques with sophisticated digital readout algorithms. This article presents a new scheme that uses strong laser frequency modulations in combination with the deep phase modulation readout algorithm to construct simpler and easily scalable interferometers. PMID:26072834

  19. Measuring PV module delamination

    SciTech Connect

    Murphy, E.B.

    1980-09-22

    Delamination of the encapsulating pottant from both substrate and silicon cells in solar photovoltaic modules has been a common occurrence. While the extent of delamination is in some cases minor, there are other cases where appreciably large areas have been affected. At this time, most delaminated areas do not appear to cause electrical degradation of modules; however, keeping track of delamination growth and rate of growth is important and has been difficult. More accurate measurement of delamination has been achieved by using an acoustic digitizer to record the pattern of delamination. With the aid of a computer, software can be generated that shows the exact areas of delamination. By periodic measrement of those types of modules prone to delamination, growth rates can be documented.

  20. Solar site test module

    NASA Technical Reports Server (NTRS)

    Kissel, R. R.; Scott, D. R.

    1980-01-01

    A solar site test module using the Rockwell AIM 65microcomputer is described. The module is designed to work at any site where an IBM site data acquisition system (SDAS) is installed and is intended primarily as a troubleshooting tool. It collects sensor information (temperatures, flow rates, etc.) and displays or prints it immediately in calibrated engineering units. It will read one sensor on demand, periodically read up to 10sensors or periodically read all sensors. Performance calculations can also be included with sensor data. Unattended operation is possible to, e.g., monitor a group of sensors once per hour. Work is underway to add a data acquisition system to the test module so that it can be used at sites which have no SDAS.

  1. Quantitative velocity modulation spectroscopy.

    PubMed

    Hodges, James N; McCall, Benjamin J

    2016-05-14

    Velocity Modulation Spectroscopy (VMS) is arguably the most important development in the 20th century for spectroscopic study of molecular ions. For decades, interpretation of VMS lineshapes has presented challenges due to the intrinsic covariance of fit parameters including velocity modulation amplitude, linewidth, and intensity. This limitation has stifled the growth of this technique into the quantitative realm. In this work, we show that subtle changes in the lineshape can be used to help address this complexity. This allows for determination of the linewidth, intensity relative to other transitions, velocity modulation amplitude, and electric field strength in the positive column of a glow discharge. Additionally, we explain the large homogeneous component of the linewidth that has been previously described. Using this component, the ion mobility can be determined. PMID:27179476

  2. Thin film module development

    NASA Technical Reports Server (NTRS)

    Jester, T.

    1985-01-01

    The design of ARCO Solar, Inc.'s Genesis G100 photovoltaic module was driven by several criteria, including environmental stability (both electrical and mechanical), consumer aesthetics, low materials costs, and manufacturing ease. The module circuitry is designed as a 12 volt battery charger, using monolithic patterning techniques on a glass superstrate. This patterning and interconnect method proves amenable to high volume, low cost production throughput, and the use of glass serves the dual role of handling ease and availability. The mechanical design of the module centers on environmental stability. Packaging of the glass superstrate circuit must provide good resistance to thermal and humidity exposure along with hi-pot insulation and hailstone impact resistance. The options considered are given. Ethylene vinyl acetate (EVA) is chosen as the pottant material for its excellent weatherability.

  3. Printed Module Interconnects

    SciTech Connect

    Stockert, Talysa R.; Fields, Jeremy D.; Pach, Gregory F.; Mauger, Scott A.; van Hest, Maikel F. A. M.

    2015-06-14

    Monolithic interconnects in photovoltaic modules connect adjacent cells in series, and are typically formed sequentially involving multiple deposition and scribing steps. Interconnect widths of 500 um every 10 mm result in 5% dead area, which does not contribute to power generation in an interconnected solar panel. This work expands on previous work that introduced an alternative interconnection method capable of producing interconnect widths less than 100 um. The interconnect is added to the module in a single step after deposition of the photovoltaic stack, eliminating the need for scribe alignment. This alternative method can be used for all types of thin film photovoltaic modules. Voltage addition with copper-indium-gallium-diselenide (CIGS) solar cells using a 2-scribe printed interconnect approach is demonstrated. Additionally, interconnect widths of 250 um are shown.

  4. Reliability of photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Ross, R. G., Jr.

    1986-01-01

    In order to assess the reliability of photovoltaic modules, four categories of known array failure and degradation mechanisms are discussed, and target reliability allocations have been developed within each category based on the available technology and the life-cycle-cost requirements of future large-scale terrestrial applications. Cell-level failure mechanisms associated with open-circuiting or short-circuiting of individual solar cells generally arise from cell cracking or the fatigue of cell-to-cell interconnects. Power degradation mechanisms considered include gradual power loss in cells, light-induced effects, and module optical degradation. Module-level failure mechanisms and life-limiting wear-out mechanisms are also explored.

  5. Power module assembly

    DOEpatents

    Campbell, Jeremy B.; Newson, Steve

    2011-11-15

    A power module assembly of the type suitable for deployment in a vehicular power inverter, wherein the power inverter has a grounded chassis, is provided. The power module assembly comprises a conductive base layer electrically coupled to the chassis, an insulating layer disposed on the conductive base layer, a first conductive node disposed on the insulating layer, a second conductive node disposed on the insulating layer, wherein the first and second conductive nodes are electrically isolated from each other. The power module assembly also comprises a first capacitor having a first electrode electrically connected to the conductive base layer, and a second electrode electrically connected to the first conductive node, and further comprises a second capacitor having a first electrode electrically connected to the conductive base layer, and a second electrode electrically connected to the second conductive node.

  6. Quantitative velocity modulation spectroscopy

    NASA Astrophysics Data System (ADS)

    Hodges, James N.; McCall, Benjamin J.

    2016-05-01

    Velocity Modulation Spectroscopy (VMS) is arguably the most important development in the 20th century for spectroscopic study of molecular ions. For decades, interpretation of VMS lineshapes has presented challenges due to the intrinsic covariance of fit parameters including velocity modulation amplitude, linewidth, and intensity. This limitation has stifled the growth of this technique into the quantitative realm. In this work, we show that subtle changes in the lineshape can be used to help address this complexity. This allows for determination of the linewidth, intensity relative to other transitions, velocity modulation amplitude, and electric field strength in the positive column of a glow discharge. Additionally, we explain the large homogeneous component of the linewidth that has been previously described. Using this component, the ion mobility can be determined.

  7. Waveform Sampler CAMAC Module

    SciTech Connect

    Freytag, D.R.; Haller, G.M.; Kang, H.; Wang, J.

    1985-09-01

    A Waveform Sampler Module (WSM) for the measurement of signal shapes coming from the multi-hit drift chambers of the SLAC SLC detector is described. The module uses a high speed, high resolution analog storage device (AMU) developed in collaboration between SLAC and Stanford University. The AMU devices together with high speed TTL clocking circuitry are packaged in a hybrid which is also suitable for mounting on the detector. The module is in CAMAC format and provides eight signal channels, each recording signal amplitude versus time in 512 cells at a sampling rate of up to 360 MHz. Data are digitized by a 12-bit ADC with a 1 ..mu..s conversion time and stored in an on-board memory accessible through CAMAC.

  8. Acoustically-Driven Trion and Exciton Modulation in Piezoelectric Two-Dimensional MoS2.

    PubMed

    Rezk, Amgad R; Carey, Benjamin; Chrimes, Adam F; Lau, Desmond W M; Gibson, Brant C; Zheng, Changxi; Fuhrer, Michael S; Yeo, Leslie Y; Kalantar-Zadeh, Kourosh

    2016-02-10

    By exploiting the very recent discovery of the piezoelectricity in odd-numbered layers of two-dimensional molybdenum disulfide (MoS2), we show the possibility of reversibly tuning the photoluminescence of single and odd-numbered multilayered MoS2 using high frequency sound wave coupling. We observe a strong quenching in the photoluminescence associated with the dissociation and spatial separation of electrons-holes quasi-particles at low applied acoustic powers. At the same applied powers, we note a relative preference for ionization of trions into excitons. This work also constitutes the first visual presentation of the surface displacement in one-layered MoS2 using laser Doppler vibrometry. Such observations are associated with the acoustically generated electric field arising from the piezoelectric nature of MoS2 for odd-numbered layers. At larger applied powers, the thermal effect dominates the behavior of the two-dimensional flakes. Altogether, the work reveals several key fundamentals governing acousto-optic properties of odd-layered MoS2 that can be implemented in future optical and electronic systems. PMID:26729449

  9. Flexible programmable logic module

    SciTech Connect

    Robertson, Perry J.; Hutchinson, Robert L.; Pierson, Lyndon G.

    2001-01-01

    The circuit module of this invention is a VME board containing a plurality of programmable logic devices (PLDs), a controlled impedance clock tree, and interconnecting buses. The PLDs are arranged to permit systolic processing of a problem by offering wide data buses and a plurality of processing nodes. The board contains a clock reference and clock distribution tree that can drive each of the PLDs with two critically timed clock references. External clock references can be used to drive additional circuit modules all operating from the same synchronous clock reference.

  10. Stirling Module Development Overview

    NASA Technical Reports Server (NTRS)

    Livingston, F. R.

    1984-01-01

    The solar parabolic dish Stirling engine electrically generating module consists of a solar collector coupled to a Stirling engine powered electrical generator. The module is designed to convert solar power to electrical power in parallel with numerous identical units coupled to an electrical utility power grid. The power conversion assembly generates up to 25 kilowatts at 480 volts potential/3 phase/alternating current. Piston rings and seals with gas leakage have not occurred, however, operator failures resulted in two burnt out receivers, while material fatigue resulted in a broken piston rod between the piston rod seal and cap seal.

  11. Photovoltaic concentrator module technology

    NASA Astrophysics Data System (ADS)

    Richards, Elizabeth H.; Chamberlin, Jay L.; Boes, Eldon C.

    Significant developments in the development of photovoltaic (PV) concentrator technology are described. Concentrator cell research, advances in PV concentrator cell technology, and PV concentrator module development are described. Reliability issues currently of concern, including the applicability of wet insulation resistance tests to concentrator modules, correlation of accelerated thermal cycling tests with life expectancy in the field, and the importance of quality assurance during manufacture, are discussed. Two PV concentrator power systems installed in 1989 are discussed. A PV concentrator initiative program established by the DOE is given, and the results of the latest cost study are presented.

  12. Avionic standard module development

    NASA Astrophysics Data System (ADS)

    Maki, Stanley C.; Cormier, Edmond P.; Piszkin, Thomas A.

    Avionics standard modules with redundancy offer substantial economic benefits compared to special-purpose processor units for the orbital transfer vehicle and advanced launch vehicle programs. A fiber optic, serial vehicle bus provides high throughput with modest hardware. A bistage, split tapered, star optical coupler uses a token-pass/token-demand protocol. It is reported that a standard module implementation of the above is a feasible, cost-effective approach to avionics design using standard buses and standard packaging. The VHSIC integrated package readily accommodates higher-speed VLSI chips as they become available.

  13. The laboratory module

    NASA Astrophysics Data System (ADS)

    Of the five modules comprising the Orbiting Quarantine Facility, the Laboratory Module must provide not only an extensive research capability to permit execution of the protocol, but also the flexibility to accommodate second-order testing if nonterrestrial life is discovered in the sample. The biocontainment barriers that protect the sample and the researchers from cross contamination are described. Specifically, the laboratory layout, laboratory equipment, the environmental control and life support system, and containment assurance procedures are discussed. The metal manipulation arm proposed for use within the biocontainment cabinets is described. Sample receipt and processing procedures are outlined.

  14. Photovoltaic module and interlocked stack of photovoltaic modules

    DOEpatents

    Wares, Brian S.

    2012-09-04

    One embodiment relates to an arrangement of photovoltaic modules configured for transportation. The arrangement includes a plurality of photovoltaic modules, each photovoltaic module including a frame having at least a top member and a bottom member. A plurality of alignment features are included on the top member of each frame, and a plurality of alignment features are included on the bottom member of each frame. Adjacent photovoltaic modules are interlocked by the alignment features on the top member of a lower module fitting together with the alignment features on the bottom member of an upper module. Other embodiments, features and aspects are also disclosed.

  15. Coast Guard Firefighting Module

    NASA Technical Reports Server (NTRS)

    1977-01-01

    NASA and the U.S. Coast Guard are jointly developing a lightweight, helicopter-transportable, completely self-contained firefighting module for combating shipboard and dockside fires. The project draws upon NASA technology in high-capacity rocket engine pumps, lightweight materials and compact packaging.

  16. Multiple trellis coded modulation

    NASA Technical Reports Server (NTRS)

    Simon, Marvin K. (Inventor); Divsalar, Dariush (Inventor)

    1990-01-01

    A technique for designing trellis codes to minimize bit error performance for a fading channel. The invention provides a criteria which may be used in the design of such codes which is significantly different from that used for average white Gaussian noise channels. The method of multiple trellis coded modulation of the present invention comprises the steps of: (a) coding b bits of input data into s intermediate outputs; (b) grouping said s intermediate outputs into k groups of s.sub.i intermediate outputs each where the summation of all s.sub.i,s is equal to s and k is equal to at least 2; (c) mapping each of said k groups of intermediate outputs into one of a plurality of symbols in accordance with a plurality of modulation schemes, one for each group such that the first group is mapped in accordance with a first modulation scheme and the second group is mapped in accordance with a second modulation scheme; and (d) outputting each of said symbols to provide k output symbols for each b bits of input data.

  17. Crew Module Overview

    NASA Technical Reports Server (NTRS)

    Redifer, Matthew E.

    2011-01-01

    The presentation presents an overview of the Crew Module development for the Pad Abort 1 flight test. The presentation describes the integration activity from the initial delivery of the primary structure through the installation of vehicle subsystems, then to flight test. A brief overview of flight test results is given.

  18. Rescue Manual. Module 4.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Instructional Materials Lab.

    This learner manual for rescuers covers the current techniques or practices required in the rescue service. The fourth of 10 modules contains 8 chapters: (1) construction and characteristics of rescue rope; (2) knots, bends, and hitches; (3) critical angles; (4) raising systems; (5) rigging; (6) using the brake-bar rack for rope rescue; (7) rope…

  19. Special Operation. Module 20.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This module on special operations, one in a series dealing with industrial sewing machines, their attachments, and operation, covers two topics: topstitching and mitering. For each topic these components are provided: an introduction, directions, an objective, learning activities, student information, a student self-check, and a check-out…

  20. Special Attachments. Module 19.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This module on special attachments, one in a series dealing with industrial sewing machines, their attachments, and operation, covers four topics: gauges; cording attachment; zipper foot; and hemming, shirring, and binding. For each topic these components are provided: an introduction, directions, an objective, learning activities, student…

  1. Drupal Contributed Modules

    2014-10-01

    These Drupal Modules extend the functionality of Drupal by including specific styles for dates and tabs, publishing options for scheduled and immediate publication of content modes, field visibility in content forms, keyword block filters (taxonomy based), adding content nodes to a specified queue for display in views, and status display of workflow settings.

  2. Rescue Manual. Module 6.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Instructional Materials Lab.

    This learner manual for rescuers covers the current techniques or practices required in the rescue service. The sixth of 10 modules contains 4 chapters: (1) industrial rescue; (2) rescue from a confined space; (3) extrication from heavy equipment; and (4) rescue operations involving elevators. Key points, an introduction, and conclusion accompany…

  3. SPACE: Intermediate Level Modules.

    ERIC Educational Resources Information Center

    Indiana State Dept. of Education, Indianapolis. Center for School Improvement and Performance.

    These modules were developed to assist teachers at the intermediate level to move away from extensive skill practice and toward more meaningful interdisciplinary learning. This packet, to be used by teachers in the summer Extended Learning Program, provides detailed thematic lesson plans matched to the Indiana Curriculum Proficiency Guide. The…

  4. Rescue Manual. Module 8.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Instructional Materials Lab.

    This learner manual for rescuers covers the current techniques or practices required in the rescue service. The eighth of 10 modules contains 6 chapters: (1) trench rescue; (2) shoring and tunneling techniques; (3) farm accident rescue; (4) wilderness search and rescue; (5) aircraft rescue; and (6) helicopter information. Key points, an…

  5. Rescue Manual. Module 2.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Instructional Materials Lab.

    This learner manual for rescuers covers the current techniques or practices required in the rescue service. The second of 10 modules contains 5 chapters: (1) patient care and handling techniques; (2) rescue carries and drags; (3) emergency vehicle operations; (4) self-contained breathing apparatus; and (5) protective clothing. Key points, an…

  6. An Integrated Teaching Module.

    ERIC Educational Resources Information Center

    Samuel, Marie R.; Seiferth, Berniece B.

    This integrated teaching module provides elementary and junior high school teachers with a "hands-on" approach to studying the Anasazi Indian. Emphasis is on creative exploration that focuses on integrating art, music, poetry, writing, geography, dance, history, anthropology, sociology, and archaeology. Replicas of artifacts, contemporary Indian…

  7. Paratransit: An Instructional Module.

    ERIC Educational Resources Information Center

    Scalici, Anthony

    A concept-based introduction to paratransit is provided in this instructional module for undergraduate and graduate transportation-related courses for disciplines such as engineering, business, marketing, and technology. The concept of paratransit generally refers to modes of transportation other than mass transit and solo-driven automobiles. The…

  8. Behavior Management: Training Module.

    ERIC Educational Resources Information Center

    Glen, Sally; McCoy, Youlonda

    This publication, the third in a series of modules designed for paraprofessionals working with handicapped children, presents objectives and related activities for three competencies in behavior management. The first competency, on the definition and underlying concepts of behavior management, focuses on the application of behavior management…

  9. Formed photovoltaic module busbars

    DOEpatents

    Rose, Douglas; Daroczi, Shan; Phu, Thomas

    2015-11-10

    A cell connection piece for a photovoltaic module is disclosed herein. The cell connection piece includes an interconnect bus, a plurality of bus tabs unitarily formed with the interconnect bus, and a terminal bus coupled with the interconnect bus. The plurality of bus tabs extend from the interconnect bus. The terminal bus includes a non-linear portion.

  10. Packaging of electronic modules

    NASA Technical Reports Server (NTRS)

    Katzin, L.

    1966-01-01

    Study of design approaches that are taken toward optimizing the packaging of electronic modules with respect to size, shape, component orientation, interconnections, and structural support. The study does not present a solution to specific packaging problems, but rather the factors to be considered to achieve optimum packaging designs.

  11. Scaling: An Items Module

    ERIC Educational Resources Information Center

    Tong, Ye; Kolen, Michael J.

    2010-01-01

    "Scaling" is the process of constructing a score scale that associates numbers or other ordered indicators with the performance of examinees. Scaling typically is conducted to aid users in interpreting test results. This module describes different types of raw scores and scale scores, illustrates how to incorporate various sources of information…

  12. Rescue Manual. Module 9.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Instructional Materials Lab.

    This learner manual for rescuers covers the current techniques or practices required in the rescue service. The ninth of 10 modules contains 7 chapters: (1) ice characteristics; (2) river characteristics and tactics for rescue; (3) water rescue techniques; (4) water rescue/recovery operations; (5) dive operations; (6) water rescue equipment; and…

  13. Product Module Rig Test

    NASA Technical Reports Server (NTRS)

    Holdeman, James D. (Technical Monitor); Chiappetta, Louis, Jr.; Hautman, Donald J.; Ols, John T.; Padget, Frederick C., IV; Peschke, William O. T.; Shirley, John A.; Siskind, Kenneth S.

    2004-01-01

    The low emissions potential of a Rich-Quench-Lean (RQL) combustor for use in the High Speed Civil Transport (HSCT) application was evaluated as part of Work Breakdown Structure (WBS) 1.0.2.7 of the NASA Critical Propulsion Components (CPC) Program under Contract NAS3-27235. Combustion testing was conducted in cell 1E of the Jet Burner Test Stand at United Technologies Research Center. Specifically, a Rich-Quench-Lean combustor, utilizing reduced scale quench technology implemented in a quench vane concept in a product-like configuration (Product Module Rig), demonstrated the capability of achieving an emissions index of nitrogen oxides (NOx EI) of 8.5 gm/Kg fuel at the supersonic flight condition (relative to the program goal of 5 gm/Kg fuel). Developmental parametric testing of various quench vane configurations in the more fundamental flametube, Single Module Rig Configuration, demonstrated NOx EI as low as 5.2. All configurations in both the Product Module Rig configuration and the Single Module Rig configuration demonstrated exceptional efficiencies, greater than 99.95 percent, relative to the program goal of 99.9 percent efficiency at supersonic cruise conditions. Sensitivity of emissions to quench orifice design parameters were determined during the parametric quench vane test series in support of the design of the Product Module Rig configuration. For the rectangular quench orifices investigated, an aspect ratio (length/width) of approximately 2 was found to be near optimum. An optimum for orifice spacing was found to exist at approximately 0.167 inches, resulting in 24 orifices per side of a quench vane, for the 0.435 inch quench zone channel height investigated in the Single Module Rig. Smaller quench zone channel heights appeared to be beneficial in reducing emissions. Measurements were also obtained in the Single Module Rig configuration on the sensitivity of emissions to the critical combustor parameters of fuel/air ratio, pressure drop, and residence

  14. Method of monolithic module assembly

    DOEpatents

    Gee, James M.; Garrett, Stephen E.; Morgan, William P.; Worobey, Walter

    1999-01-01

    Methods for "monolithic module assembly" which translate many of the advantages of monolithic module construction of thin-film PV modules to wafered c-Si PV modules. Methods employ using back-contact solar cells positioned atop electrically conductive circuit elements affixed to a planar support so that a circuit capable of generating electric power is created. The modules are encapsulated using encapsulant materials such as EVA which are commonly used in photovoltaic module manufacture. The methods of the invention allow multiple cells to be electrically connected in a single encapsulation step rather than by sequential soldering which characterizes the currently used commercial practices.

  15. Lunar Module 5 mated with Spacecraft Lunar Module Adapter (SLA)

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Interior view of the Kennedy Space Center's (KSC) Manned Spacecraft Operations Building showing Lunar Module 5 mated to its Spacecraft Lunar Module Adapter (SLA). LM-5 is scheduled to be flown on the Apollo 11 lunar landing mission.

  16. Imaging spectroscopy; Proceedings of the Seminar, Los Angeles, CA, February 10, 11, 1981

    NASA Technical Reports Server (NTRS)

    Norris, D. D.

    1981-01-01

    The seminar concentrated on the science applications of spectral imaging, multispectral imaging sensors, and spectral filtering. Papers are presented on spectroscopic remote sensing for geological applications, spectral mapping of Jupiter, system design of an interferometer imaging sounder and a common module imaging spectral radiometer. Other topics discussed include the performance and application of an intensified linear self-scanned array instrument, tunable optical filtering using an interferometer for selective modulation, design studies for a spectrally agile staring sensor system, and acousto-optic tunable filters for high-resolution spectral analysis.

  17. Optical Distance Measurement Device And Method Thereof

    DOEpatents

    Bowers, Mark W.

    2004-06-15

    A system and method of efficiently obtaining distance measurements of a target by scanning the target. An optical beam is provided by a light source and modulated by a frequency source. The modulated optical beam is transmitted to an acousto-optical deflector capable of changing the angle of the optical beam in a predetermined manner to produce an output for scanning the target. In operation, reflected or diffused light from the target may be received by a detector and transmitted to a controller configured to calculate the distance to the target as well as the measurement uncertainty in calculating the distance to the target.

  18. High power rapidly tunable system for laser cooling.

    PubMed

    Valenzuela, V M; Hernández, L; Gomez, E

    2012-01-01

    We present a laser configuration capable of fast frequency changes with a high power output and a large tuning range. The system integrates frequency tuning with an acousto-optic modulator with a double pass tapered amplifier. A compensation circuit keeps the seed power constant and prevents damage to the amplifier. A single mode fiber decouples the modulation and amplification sections and keeps the alignment fixed. The small power required to saturate the amplifier makes the system very reliable. We use the system to obtain a dipole trap that we image using a beam derived from the same configuration. PMID:22299990

  19. Artificial long-delay optical processor

    NASA Astrophysics Data System (ADS)

    Kornreich, Philipp G.; Smith, Jacqueline D.

    1993-02-01

    The Artificial Long Delay Optical Processor (ALDOP) generates a large variable delay of a band limited pulse modulated RF signal. The proposed prototype ALDOP has potential use in a Passive Radio Ranging (PRR) system operating in the 82.5 - 97.5 MHz frequency band. The complete system will combine a passive electronic band pass filter with the optically based ALDOP to impart a unique phase shift to each frequency component of an incoming RF signal. The phase shift is generated using optical heterodyne methods that incorporate the transmission and modulation of light through a series of optical components including an acousto-optical cell and a Fresnel Zone Plate.

  20. Artinianness of local cohomology modules

    NASA Astrophysics Data System (ADS)

    Aghapournahr, Moharram; Melkersson, Leif

    2014-04-01

    Some uniform theorems on the artinianness of certain local cohomology modules are proven in a general situation. They generalize and imply previous results about the artinianness of some special local cohomology modules in the graded case.

  1. Multiple-Trellis-Coded Modulation

    NASA Technical Reports Server (NTRS)

    Divsalar, D.; Simon, M. K.

    1990-01-01

    Theoretical gain over simple multiple-phase-shift keying at least 2 to 3 decibels. Multiple-trellis-coded modulation scheme combined with M-ary modulation shows theoretically to yield asymptotic gains in performance over uncoded multiple-phase-shift keying, while employing symmetric multiple-phase-shift signal constellations and avoiding code catastrophe. Suitable for satellite and terrestrial-mobile/satellite communications or other communications requiring burst-error correction. Extended to such higher dimensional modulations as quadrature amplitude modulation.

  2. Axially Modulated Plasma Waveguides

    SciTech Connect

    Layer, B. D.; York, A. G.; Varma, S.; Chen, Y.-H.; Milchberg, H. M.

    2009-01-22

    We demonstrate two techniques for making periodically modulated plasma waveguides-one with sharp, stable voids as short as 50 {mu}m with a period as small as 200 {mu}m, and another which modulates the waveguide diameter with a corrugation period as short as 35 {mu}m[1]. These features persist as the plasma expands for the full lifetime of the waveguide (>6 ns). The waveguides were made using the hydrodynamic shock method in a cluster jet using hydrogen, nitrogen, and argon. We demonstrate guided propagation at intensities up to 2x10{sup 17} W/cm{sup 2}, limited by our laser energy currently available. This technique is useful for quasi-phase matching to allow efficient coupling of laser energy to acceleration of relativistic electrons or generation of coherent electromagnetic radiation at selected frequencies.

  3. Parabolic dish module experiment

    NASA Astrophysics Data System (ADS)

    1986-03-01

    A development test model of the 8-meter Solar Brayton Parabolic Dish Module has been designed, fabricated, and tested. The test model consists of five major subsystems: Sanders ceramic honeycomb solar receiver; LaJet LEC460 solar concentrator; AiRsearch SABC MKIIIA engine, Abacus 8 kW ac inverter; and a Sanders designed and built system controller. Goals of the tests were to integrate subsystem components into a working module, demonstrate the concept, and generate 5 kWe (hybrid) and 4.7 kWe (solar only) input. All subsystem integration goals were successfully achieved, but system performance efficiency was lower than expected. Contributing causes of the lower performance efficiencies have been identified. Modifications needed to restore performance to the required levels and improve the system life cycle cost have been addressed and are the subject of this final report.

  4. 30% CPV Module Milestone

    NASA Astrophysics Data System (ADS)

    Gordon, Robert; Kinsey, Geoff; Nayaak, Adi; Garboushian, Vahan

    2010-10-01

    Concentrating Photovoltaics has held out the promise of low cost solar electricity for now several decades. Steady progress towards this goal in the 80's and 90's gradually produced more efficient and reliable systems. System efficiency is regarded as the largest factor in lowering the electricity cost and the relatively recent advent of the terrestrial multi-junction solar cell has pressed this race forward dramatically. CPV systems are now exhibiting impressive AC field efficiencies of 25% and more, approximately twice that of the best flat plate systems available today. Amonix inc. has just tested their latest generation multi-junction module design, achieving over 31% DC efficiency at near PVUSA test conditions. Inculcating this design into their next MegaModule is forthcoming, but the expected AC system field efficiency should be significantly higher than current 25% levels.

  5. Silicon Optical Modulator Simulation

    NASA Astrophysics Data System (ADS)

    LIM, Soon; Sun, Min Jie; Png, Ching

    2015-04-01

    We developed a way of predicting and analyzing high speed optical modulator. Our research adopted a bottom-up approach to consider high-speed optical links using an eye diagram. Our method leverages on modular “mapping” of electrical characteristics to optical characteristics, while attaining the required accuracy necessary for device footprint approaching sub-micron scales where electrical data distribution varies drastically. We calculate for the bias dependent phase shift (2pi/mm) and loss (dB/mm) for the optical modulator based on the real and imaginary part of complex effective indices. Subsequently, combine effectively both the electrical and optical profiles to construct the optical eye diagram which is the essential gist of signal integrity of such devices.

  6. VERDE Analytic Modules

    2008-01-15

    The Verde Analytic Modules permit the user to ingest openly available data feeds about phenomenology (storm tracks, wind, precipitation, earthquake, wildfires, and similar natural and manmade power grid disruptions and forecast power outages, restoration times, customers outaged, and key facilities that will lose power. Damage areas are predicted using historic damage criteria of the affected area. The modules use a cellular automata approach to estimating the distribution circuits assigned to geo-located substations. Population estimates servedmore » within the service areas are located within 1 km grid cells and converted to customer counts by conversion through demographic estimation of households and commercial firms within the population cells. Restoration times are estimated by agent-based simulation of restoration crews working according to utility published prioritization calibrated by historic performance.« less

  7. Bacteriophage replication modules.

    PubMed

    Weigel, Christoph; Seitz, Harald

    2006-05-01

    Bacteriophages (prokaryotic viruses) are favourite model systems to study DNA replication in prokaryotes, and provide examples for every theoretically possible replication mechanism. In addition, the elucidation of the intricate interplay of phage-encoded replication factors with 'host' factors has always advanced the understanding of DNA replication in general. Here we review bacteriophage replication based on the long-standing observation that in most known phage genomes the replication genes are arranged as modules. This allows us to discuss established model systems--f1/fd, phiX174, P2, P4, lambda, SPP1, N15, phi29, T7 and T4--along with those numerous phages that have been sequenced but not studied experimentally. The review of bacteriophage replication mechanisms and modules is accompanied by a compendium of replication origins and replication/recombination proteins (available as supplementary material online). PMID:16594962

  8. Stable local oscillator module.

    SciTech Connect

    Brocato, Robert Wesley

    2007-11-01

    This report gives a description of the development of a Stable Local Oscillator (StaLO) multi-chip module (MCM). It is a follow-on report to SAND2006-6414, Stable Local Oscillator Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. This report describes the development of an MCM-based version of the complete StaLO, fabricated on an alumina thick film hybrid substrate.

  9. VERDE Analytic Modules

    SciTech Connect

    2008-01-15

    The Verde Analytic Modules permit the user to ingest openly available data feeds about phenomenology (storm tracks, wind, precipitation, earthquake, wildfires, and similar natural and manmade power grid disruptions and forecast power outages, restoration times, customers outaged, and key facilities that will lose power. Damage areas are predicted using historic damage criteria of the affected area. The modules use a cellular automata approach to estimating the distribution circuits assigned to geo-located substations. Population estimates served within the service areas are located within 1 km grid cells and converted to customer counts by conversion through demographic estimation of households and commercial firms within the population cells. Restoration times are estimated by agent-based simulation of restoration crews working according to utility published prioritization calibrated by historic performance.

  10. Weighted network modules

    NASA Astrophysics Data System (ADS)

    Farkas, Illés; Ábel, Dániel; Palla, Gergely; Vicsek, Tamás

    2007-06-01

    The inclusion of link weights into the analysis of network properties allows a deeper insight into the (often overlapping) modular structure of real-world webs. We introduce a clustering algorithm clique percolation method with weights (CPMw) for weighted networks based on the concept of percolating k-cliques with high enough intensity. The algorithm allows overlaps between the modules. First, we give detailed analytical and numerical results about the critical point of weighted k-clique percolation on (weighted) Erdos Rényi graphs. Then, for a scientist collaboration web and a stock correlation graph we compute three-link weight correlations and with the CPMw the weighted modules. After reshuffling link weights in both networks and computing the same quantities for the randomized control graphs as well, we show that groups of three or more strong links prefer to cluster together in both original graphs.

  11. Vapor compression distillation module

    NASA Technical Reports Server (NTRS)

    Nuccio, P. P.

    1975-01-01

    A Vapor Compression Distillation (VCD) module was developed and evaluated as part of a Space Station Prototype (SSP) environmental control and life support system. The VCD module includes the waste tankage, pumps, post-treatment cells, automatic controls and fault detection instrumentation. Development problems were encountered with two components: the liquid pumps, and the waste tank and quantity gauge. Peristaltic pumps were selected instead of gear pumps, and a sub-program of materials and design optimization was undertaken leading to a projected life greater than 10,000 hours of continuous operation. A bladder tank was designed and built to contain the waste liquids and deliver it to the processor. A detrimental pressure pattern imposed upon the bladder by a force-operated quantity gauge was corrected by rearranging the force application, and design goals were achieved. System testing has demonstrated that all performance goals have been fulfilled.

  12. Module isolation devices

    SciTech Connect

    Carolan, Michael Francis; Cooke, John Albert; Buzinski, Michael David

    2010-04-27

    A gas flow isolation device includes a gas flow isolation valve movable from an opened condition to a closed condition. The module isolation valve in one embodiment includes a rupture disk in flow communication with a flow of gas when the module isolation valve is in an opened condition. The rupture disk ruptures when a predetermined pressure differential occurs across it causing the isolation valve to close. In one embodiment the valve is mechanically linked to the rupture disk to maintain the valve in an opened condition when the rupture disk is intact, and which permits the valve to move into a closed condition when the rupture disk ruptures. In another embodiment a crushable member maintains the valve in an open condition, and the flow of gas passed the valve upon rupturing of the rupture disk compresses the crushable member to close the isolation valve.

  13. Modulated Elliptical Slot

    NASA Technical Reports Server (NTRS)

    Abou-Khousa, M. A.

    2009-01-01

    A novel modulated slot design has been proposed and tested. The proposed slot is aimed to replace the inefficient small dipoles used in conventional MST-based imaging systems. The developed slot is very attractive as MST array element due to its small size and high efficiency/modulation depth. In fact, the developed slot has been successfully used to implement the first prototype of a microwave camera operating at 24 GHZ. It is also being used in the design of the second generation of the camera. Finally, the designed elliptical slot can be used as an electronically controlled waveguide iris for many other purposes (for instance in constructing waveguide reflective phase shifters and multiplexers/switches).

  14. Lightweight Trauma Module - LTM

    NASA Technical Reports Server (NTRS)

    Hatfield, Thomas

    2008-01-01

    Current patient movement items (PMI) supporting the military's Critical Care Air Transport Team (CCATT) mission as well as the Crew Health Care System for space (CHeCS) have significant limitations: size, weight, battery duration, and dated clinical technology. The LTM is a small, 20 lb., system integrating diagnostic and therapeutic clinical capabilities along with onboard data management, communication services and automated care algorithms to meet new Aeromedical Evacuation requirements. The Lightweight Trauma Module is an Impact Instrumentation, Inc. project with strong Industry, DoD, NASA, and Academia partnerships aimed at developing the next generation of smart and rugged critical care tools for hazardous environments ranging from the battlefield to space exploration. The LTM is a combination ventilator/critical care monitor/therapeutic system with integrated automatic control systems. Additional capabilities are provided with small external modules.

  15. Headstart German Program. Module 6.

    ERIC Educational Resources Information Center

    Defense Language Inst., Monterey, CA.

    This is the sixth module of 10 in the German Headstart program. Each of the 2 units in the module contains objectives, exercises, and a self-evaluation quiz. In addition, there are several supplementary exercises and self-evaluations. The objective of this module is to familiarize the student with expressions connected with various kinds of…

  16. Headstart German Program. Module 7.

    ERIC Educational Resources Information Center

    Defense Language Inst., Monterey, CA.

    This is the seventh module of 10 in the German Headstart program. Each of the 2 units in the module contains objectives, exercises, and a self-evaluation quiz. In addition, there are several supplementary exercises and self-evaluations. The objective of this module is to enable the student to use all the services of a German post-office, such as…

  17. Headstart German Program. Module 5.

    ERIC Educational Resources Information Center

    Defense Language Inst., Monterey, CA.

    This is the fifth module of 10 in the German Headstart program. Each of the 3 units in the module contains objectives, exercises, and a self-evaluation quiz. In addition, there are several supplementary exercises and self-evaluations. The objective of this module is to enable the student to use and understand: (1) courtesy expressions; (2) time…

  18. Headstart German Program. Module 9.

    ERIC Educational Resources Information Center

    Defense Language Inst., Monterey, CA.

    This is the ninth module of 10 in the German Headstart program. The single unit in the module contains objectives, exercises, and a self-evaluation quiz. In addition, there are several supplementary exercises and self-evaluations. The objective of this module is to familiarize the student with some of the terminology used by military personnel in…

  19. Graded Hilbert C*-modules

    SciTech Connect

    Wang, Chunxiang

    2014-02-15

    The notion of Hilbert C*-modules graded by a semilattice was first introduced in the study of many-body systems. We show the relationship between these Hilbert C*-modules and their homogeneous subspaces. We study the stability of graded Hilbert C*-modules under tensor products and crossed products.

  20. Thermal modulation for gas chromatography

    NASA Technical Reports Server (NTRS)

    Hasselbrink, Ernest F. (Inventor); Libardoni, Mark (Inventor); Stewart, Kristine (Inventor); Waite, J. Hunter (Inventor); Block, Bruce P. (Inventor); Sacks, Richard D. (Inventor)

    2007-01-01

    A thermal modulator device for gas chromatography and associated methods. The thermal modulator device includes a recirculating fluid cooling member, an electrically conductive capillary in direct thermal contact with the cooling member, and a power supply electrically coupled to the capillary and operable for controlled resistive heating of the capillary. The capillary can include more than one separate thermally modulated sections.

  1. Assessing Current Status. Module 4.

    ERIC Educational Resources Information Center

    DuBois, Phyllis

    This staff development module is part of one of three groups of career guidance modules developed, field-tested and revised by a six-state consortium coordinated by the American Institutes for Research. This module is the fourth in a series on developing a comprehensive career guidance program at the high school level, designed to aid guidance…

  2. Tandem resonator reflectance modulator

    DOEpatents

    Fritz, Ian J.; Wendt, Joel R.

    1994-01-01

    A wide band optical modulator is grown on a substrate as tandem Fabry-Perot resonators including three mirrors spaced by two cavities. The absorption of one cavity is changed relative to the absorption of the other cavity by an applied electric field, to cause a change in total reflected light, as light reflecting from the outer mirrors is in phase and light reflecting from the inner mirror is out of phase with light from the outer mirrors.

  3. Tandem resonator reflectance modulator

    DOEpatents

    Fritz, I.J.; Wendt, J.R.

    1994-09-06

    A wide band optical modulator is grown on a substrate as tandem Fabry-Perot resonators including three mirrors spaced by two cavities. The absorption of one cavity is changed relative to the absorption of the other cavity by an applied electric field, to cause a change in total reflected light, as light reflecting from the outer mirrors is in phase and light reflecting from the inner mirror is out of phase with light from the outer mirrors. 8 figs.

  4. Chemical release module facility

    NASA Technical Reports Server (NTRS)

    Reasoner, D. L.

    1980-01-01

    The chemical release module provides the capability to conduct: (1) thermite based metal vapor releases; (2) pressurized gas releases; (3) dispersed liquid releases; (4) shaped charge releases from ejected submodules; and (5) diagnostic measurements with pi supplied instruments. It also provides a basic R-F and electrical system for: (1) receiving and executing commands; (2) telemetering housekeeping data; (3) tracking; (4) monitoring housekeeping and control units; and (5) ultrasafe disarming and control monitoring.

  5. Nuclear waste packing module

    SciTech Connect

    Mallory, C.W.; Watts, R.E.; Sanner, W.S. Jr.; Disibio, R.R.; Liley, A.W.; Winston, S.J.; Stricklin, B.C.; Razor, J.E.

    1989-07-04

    This patent describes a module for encapsulating radioactive waste contained within inner containers in a structurally stable form capable of bearing a compressive load. The module comprising a rigid outer container which completely surrounds the waste for providing a first radiation and water barrier for the waste and the exterior of the rigid outer container having the shape of a right angle hexagonal prism with substantially planar, non-interlocking face and the surfaces that allow relative planar motion with adjacent similar outer containers, a plurality of inner containers for providing a second radiation barrier for the waste. The inner containers compacted by a force which inelastically deforms both the inner containers and their contents to increase the overall compressive strength of the module by increasing the compressive strength of the inner containers. The plurality of inner containers stacked in a plurality of stacks within the interior of the rigid outer container, and a central layer of a fluent, hardenable substance which fills the space between the outer and inner containers.

  6. Allosteric modulation of caspases.

    PubMed

    Häcker, Hans-Georg; Sisay, Mihiret Tekeste; Gütschow, Michael

    2011-11-01

    Caspases are proteolytic enzymes mainly involved in the induction and execution phases of apoptosis. This type of programmed cell death is an essential regulatory process required to maintain the integrity and homeostasis of multicellular organisms. Inappropriate apoptosis is attributed a key role in many human diseases, including neurodegenerative disorders, ischemic damage, autoimmune diseases and cancer. Allosteric modulation of the function of a protein occurs when the regulatory trigger, such as the binding of a small effector or inhibitor molecule, takes place some distance from the protein's active site. In recent years, several caspases have been identified that possess allosteric sites and binding of small molecule to these sites resulted in the modulation of enzyme activities. Regulation of caspase activity by small molecule allosteric modulators is believed to be of great therapeutic importance. In this review we give brief highlights on recent developments in identifying and characterizing natural and synthetic allosteric inhibitors as well as activators of caspases and discuss their potential in drug discovery and protein engineering. PMID:21807025

  7. Improved bunch spreader modules

    SciTech Connect

    Ieiri, Takao

    1989-07-20

    In order to raise the threshold beam current of instabilities in the fixed target run, it is required to increase the longitudinal emittance, and hence the bunch length. The bunch spreader used a noise generator through a sharp-cut ban pass filter (BPF) instead of a coherent signal. In that filter, the pass band frequency was near twice the synchrotron frequency 2f/sub s/. The bandwidth of the filter was fixed between 350Hz and 600Hz, though twice the synchrotron frequency changed from 500Hz to 300Hz after transition in Main Ring. The noise through the filter is applied to an RF amplitude modulator. In the Tevatron, where the synchrotron frequency f/sub s/ varies from 120Hz to 40Hz during acceleration, the noise is applied to a phase shifter at the frequency of f/sub s/. So, we need a tunable filter which tracks 2f/sub s/ in the Main Ring and f/sub s/ in the Tevatron. This note describes details of improved bunch spreader modules using a tunable filter used in both the Main Ring and the Tevatron. A brief description about this module along with a beam test done in the Main Ring is shown. 3 refs., 6 figs.

  8. Receiver Gain Modulation Circuit

    NASA Technical Reports Server (NTRS)

    Jones, Hollis; Racette, Paul; Walker, David; Gu, Dazhen

    2011-01-01

    A receiver gain modulation circuit (RGMC) was developed that modulates the power gain of the output of a radiometer receiver with a test signal. As the radiometer receiver switches between calibration noise references, the test signal is mixed with the calibrated noise and thus produces an ensemble set of measurements from which ensemble statistical analysis can be used to extract statistical information about the test signal. The RGMC is an enabling technology of the ensemble detector. As a key component for achieving ensemble detection and analysis, the RGMC has broad aeronautical and space applications. The RGMC can be used to test and develop new calibration algorithms, for example, to detect gain anomalies, and/or correct for slow drifts that affect climate-quality measurements over an accelerated time scale. A generalized approach to analyzing radiometer system designs yields a mathematical treatment of noise reference measurements in calibration algorithms. By treating the measurements from the different noise references as ensemble samples of the receiver state, i.e. receiver gain, a quantitative description of the non-stationary properties of the underlying receiver fluctuations can be derived. Excellent agreement has been obtained between model calculations and radiometric measurements. The mathematical formulation is equivalent to modulating the gain of a stable receiver with an externally generated signal and is the basis for ensemble detection and analysis (EDA). The concept of generating ensemble data sets using an ensemble detector is similar to the ensemble data sets generated as part of ensemble empirical mode decomposition (EEMD) with exception of a key distinguishing factor. EEMD adds noise to the signal under study whereas EDA mixes the signal with calibrated noise. It is mixing with calibrated noise that permits the measurement of temporal-functional variability of uncertainty in the underlying process. The RGMC permits the evaluation of EDA by

  9. Accumulate Repeat Accumulate Coded Modulation

    NASA Technical Reports Server (NTRS)

    Abbasfar, Aliazam; Divsalar, Dariush; Yao, Kung

    2004-01-01

    In this paper we propose an innovative coded modulation scheme called 'Accumulate Repeat Accumulate Coded Modulation' (ARA coded modulation). This class of codes can be viewed as serial turbo-like codes, or as a subclass of Low Density Parity Check (LDPC) codes that are combined with high level modulation. Thus at the decoder belief propagation can be used for iterative decoding of ARA coded modulation on a graph, provided a demapper transforms the received in-phase and quadrature samples to reliability of the bits.

  10. AC photovoltaic module magnetic fields

    SciTech Connect

    Jennings, C.; Chang, G.J.; Reyes, A.B.; Whitaker, C.M.

    1997-12-31

    Implementation of alternating current (AC) photovoltaic (PV) modules, particularly for distributed applications such as PV rooftops and facades, may be slowed by public concern about electric and magnetic fields (EMF). This paper documents magnetic field measurements on an AC PV module, complementing EMF research on direct-current PV modules conducted by PG and E in 1993. Although not comprehensive, the PV EMF data indicate that 60 Hz magnetic fields (the EMF type of greatest public concern) from PV modules are comparable to, or significantly less than, those from household appliances. Given the present EMF research knowledge, AC PV module EMF may not merit considerable concern.

  11. Brewers’ rice modulates oxidative stress in azoxymethane-mediated colon carcinogenesis in rats

    PubMed Central

    Tan, Bee Ling; Norhaizan, Mohd Esa; Huynh, Ky; Yeap, Swee Keong; Hazilawati, Hamzah; Roselina, Karim

    2015-01-01

    AIM: To investigate the mechanistic action of brewers’ rice in regulating the Wnt/nuclear factor-kappa B (NF-κB)/Nrf2-signaling pathways during colon carcinogenesis in male Sprague-Dawley rats. METHODS: Male Sprague-Dawley rats were randomly divided into the following five groups (six rats in each group): (G1) normal, (G2) azoxymethane (AOM) alone, (G3) AOM + 10% (weight (w)/weight (w)) brewers’ rice, (G4) AOM + 20% (w/w) brewers’ rice, and (G5) AOM + 40% (w/w) brewers’ rice. They were intraperitoneally administered 15 mg/kg body weight of AOM in saline once weekly over a two-week period and treated with an American Institute of Nutrition (AIN)-93G diet containing 10%, 20%, and 40% (w/w) brewers’ rice. The mRNA levels of glycogen synthase kinase 3β (GSK3β), β-catenin, key inflammation markers, nuclear factor E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1)-dependent transcriptional activity were assessed by quantitative real-time polymerase chain reaction analyses. The colon superoxide dismutase, malondialdehyde, and nitric oxide levels were also analyzed to assess the antioxidant effect of these treatments. The results were analyzed using one-way analysis of variance (ANOVA), and a P value of < 0.05 was considered significant. RESULTS: The overall analyses demonstrated that the dietary administration of brewers’ rice in AOM-induced rat colon carcinogenesis resulted in the transcriptional upregulation of GSK3β, inducible nitric oxide synthase (iNOS), Nrf2, and HO-1. We discovered that the dietary administration of brewers’ rice downregulated the β-catenin and NF-κB mRNA levels. A significant reduction in β-catenin expression was found in the groups administered with 20% (0.611 ± 0.034) and 40% (0.436 ± 0.045) (w/w) brewers’ rice compared with that of the group treated with AOM alone (1.000 ± 0.064) (P < 0.05). The NF-κB expression was significantly lower between the AOM-alone group (1.000 ± 0.048) and those groups fed with diets

  12. 47 CFR 87.141 - Modulation requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... frequency modulated transmitter operating in the band 72.0-76.0 MHz must have a modulation limiter. (f) Each frequency modulated transmitter equipped with a modulation limiter must have a low pass filter between the modulation limiter and the modulated stage. At audio frequencies between 3 kHz and 15 kHz, the filter...

  13. 47 CFR 87.141 - Modulation requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... frequency modulated transmitter operating in the band 72.0-76.0 MHz must have a modulation limiter. (f) Each frequency modulated transmitter equipped with a modulation limiter must have a low pass filter between the modulation limiter and the modulated stage. At audio frequencies between 3 kHz and 15 kHz, the filter...

  14. 47 CFR 87.141 - Modulation requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... frequency modulated transmitter operating in the band 72.0-76.0 MHz must have a modulation limiter. (f) Each frequency modulated transmitter equipped with a modulation limiter must have a low pass filter between the modulation limiter and the modulated stage. At audio frequencies between 3 kHz and 15 kHz, the filter...

  15. Modulation of whistlers

    NASA Astrophysics Data System (ADS)

    Sivokon', V. P.; Bogdanov, V. V.; Druzhin, G. I.; Cherneva, N. V.; Kubyshkin, A. V.; Sannikov, D. V.; Agranat, I. V.

    2014-11-01

    Analysis of the experimental data obtained at Paratunka observatory (53.02° N, 158.65° E; L = 2.3) has revealed a nonstandard form of whistlers involving spectral lines that are symmetric with respect to the whistler. We have shown that this form is most likely due to the amplitude modulation of whistlers by electromagnetic pulses with a length of around 1 s and carrier frequency of around 1.1 kHz. We have suggested that these pulses could be emitted by the auroral electrojet modified by heating radiation from the HAARP facility (62.30° N, 145.30° W; L > 4.2).

  16. Exothermic furnace module

    NASA Technical Reports Server (NTRS)

    Poorman, R. M. (Inventor)

    1982-01-01

    An exothermic furnace module is disclosed for processing materials in space which includes an insulated casing and a sample support, carried within the casing which supports a sample container. An exothermic heat source includes a plurality of segments of exothermic material stacked one upon another to produce a desired temperature profile when ignited. The exothermic material segments are constructed in the form of an annular element having a recess opening which defines an open central core throughout the vertical axis of the stacked exothermic material. The sample container is arranged within the core of the stacked exothermic heating material.

  17. TASMANIAN Sparse Grids Module

    SciTech Connect

    and Drayton Munster, Miroslav Stoyanov

    2013-09-20

    Sparse Grids are the family of methods of choice for multidimensional integration and interpolation in low to moderate number of dimensions. The method is to select extend a one dimensional set of abscissas, weights and basis functions by taking a subset of all possible tensor products. The module provides the ability to create global and local approximations based on polynomials and wavelets. The software has three components, a library, a wrapper for the library that provides a command line interface via text files ad a MATLAB interface via the command line tool.

  18. TASMANIAN Sparse Grids Module

    2013-09-20

    Sparse Grids are the family of methods of choice for multidimensional integration and interpolation in low to moderate number of dimensions. The method is to select extend a one dimensional set of abscissas, weights and basis functions by taking a subset of all possible tensor products. The module provides the ability to create global and local approximations based on polynomials and wavelets. The software has three components, a library, a wrapper for the library thatmore » provides a command line interface via text files ad a MATLAB interface via the command line tool.« less

  19. Combining modules for movement.

    PubMed

    Bizzi, E; Cheung, V C K; d'Avella, A; Saltiel, P; Tresch, M

    2008-01-01

    We review experiments supporting the hypothesis that the vertebrate motor system produces movements by combining a small number of units of motor output. Using a variety of approaches such as microstimulation of the spinal cord, NMDA iontophoresis, and an examination of natural behaviors in intact and deafferented animals we have provided evidence for a modular organization of the spinal cord. A module is a functional unit in the spinal cord that generates a specific motor output by imposing a specific pattern of muscle activation. Such an organization might help to simplify the production of movements by reducing the degrees of freedom that need to be specified. PMID:18029291

  20. Processing module operating methods, processing modules, and communications systems

    DOEpatents

    McCown, Steven Harvey; Derr, Kurt W.; Moore, Troy

    2014-09-09

    A processing module operating method includes using a processing module physically connected to a wireless communications device, requesting that the wireless communications device retrieve encrypted code from a web site and receiving the encrypted code from the wireless communications device. The wireless communications device is unable to decrypt the encrypted code. The method further includes using the processing module, decrypting the encrypted code, executing the decrypted code, and preventing the wireless communications device from accessing the decrypted code. Another processing module operating method includes using a processing module physically connected to a host device, executing an application within the processing module, allowing the application to exchange user interaction data communicated using a user interface of the host device with the host device, and allowing the application to use the host device as a communications device for exchanging information with a remote device distinct from the host device.

  1. Phase modulation in RF tag

    DOEpatents

    Carrender, Curtis Lee; Gilbert, Ronald W.

    2007-02-20

    A radio frequency (RF) communication system employs phase-modulated backscatter signals for RF communication from an RF tag to an interrogator. The interrogator transmits a continuous wave interrogation signal to the RF tag, which based on an information code stored in a memory, phase-modulates the interrogation signal to produce a backscatter response signal that is transmitted back to the interrogator. A phase modulator structure in the RF tag may include a switch coupled between an antenna and a quarter-wavelength stub; and a driver coupled between the memory and a control terminal of the switch. The driver is structured to produce a modulating signal corresponding to the information code, the modulating signal alternately opening and closing the switch to respectively decrease and increase the transmission path taken by the interrogation signal and thereby modulate the phase of the response signal. Alternatively, the phase modulator may include a diode coupled between the antenna and driver. The modulating signal from the driver modulates the capacitance of the diode, which modulates the phase of the response signal reflected by the diode and antenna.

  2. DC bias modulation characteristics of longitudinal KD*P modulators

    NASA Astrophysics Data System (ADS)

    West, Ed; Wilkins, Nathan

    1992-12-01

    A test program designed to study the DC modulation characteristics of longitudinal KD*P modulators and to determine what electrode structure might improve the performance of these devices is presented which was developed in the Marshall Space Flight Center. The physical constraints of these devices and the necessary electrical characteristics that the KD*P modulators must have to be used in the MSFC polarimeter are discussed.

  3. View of Apollo 13 Lunar Module from the Command Module

    NASA Technical Reports Server (NTRS)

    1970-01-01

    This view of the Apollo 13 Lunar Module (LM) was photographed from the Command Module (CM) just after the LM had been jettisoned. The jettisoning occurred a few minutes after 11 a.m., April 17, 1970, just over an hour prior to splashdown of the CM in the South Pacific Ocean. The apparent explosion of oxygen tank number two in the Apoll 13 Service Module caused the Apollo 13 crewmen to rely on the LM as a 'lifeboat'.

  4. Protective Effects of Turbinaria ornata and Padina pavonia against Azoxymethane-Induced Colon Carcinogenesis through Modulation of PPAR Gamma, NF-κB and Oxidative Stress.

    PubMed

    Mahmoud, Ayman M; Abdella, Ehab M; El-Derby, Azza M; Abdella, Eman M

    2015-05-01

    The aim of this study was to investigate the antiproliferative and protective effects of the brown seaweeds, Turbinaria ornata and Padina pavonia, against azoxymethane (AOM)-induced colon carcinogenesis in mice. Both algal extracts showed anti-proliferative effects on the human carcinoma cell line HCT-116 in vitro, with T. ornata demonstrating a more potent effect. Male albino Swiss mice received intraperitoneal injections of AOM (10 mg/kg) once a week for two consecutive weeks and 100 mg/kg of either T. ornata or P. pavonia extracts. AOM-induced mice exhibited alterations in the histological structure of the colon, elevated lipid peroxidation and nitric oxide, declined glutathione content and reduced activity of superoxide dismutase and glutathione peroxidase. In addition, AOM induced downregulation of peroxisome proliferator activated receptor gamma (PPARγ) and p53 mRNA expression, with concomitant upregulation of nuclear factor-kappa B (NF-κB) in colon tissue. Administration of either algal extract markedly alleviated the recorded alterations. In conclusion, the current study suggests that T. ornata and P. pavonia, through their antioxidant and anti-inflammatory effects, are able to attenuate colon inflammation by downregulating NF-κB expression. Furthermore, the protective effects of both algae against AOM-initiated carcinogenesis were attributed, at least in part, to their ability to upregulate colonic PPARγ and p53 expression. PMID:25676613

  5. Influence of module requirements on flat plate module design evolution

    NASA Technical Reports Server (NTRS)

    Arnett, J. C.; Ross, R. G., Jr.

    1980-01-01

    Photovoltaic module design features and performance characteristics have undergone significant evolutionary changes between pre-1975 First Generation configurations and current Third Generation design technology. A major contributor to this evolution was an iterative process of continuing design guideline and specification development for major module procurements. Module manufacturers have actively responded to these evolving requirements through progressively improving designs. This iterative/feedback process is described. Interim design guidelines and preliminary design options reflecting the LSA 1982 Module Technical Readiness Specification (November 1979) are described with respect to previous design and performance requirements.

  6. Whole Module Offgas Test Report: Space-Xl Dragon Module

    NASA Technical Reports Server (NTRS)

    James, John T.

    2012-01-01

    On September 26 and September 28,2012 a chemist from the JSC Toxicology Group acquired samples of air in 500 m1 evacuated canisters from the sealed Space-Xl Dragon Module. One sample was also acquired from Space-X Facility near the module at the start of the test. Samples of the module air were taken in triplicate once the module had been sealed, and then taken again in triplicate 1.98 days later. Ofthe triplicate samples, the first served as a line purge, and the last two were analyzed. The results of 5 samples are reported.

  7. Externally modulated theranostic nanoparticles

    PubMed Central

    Urban, Cordula; Urban, Alexander S.; Charron, Heather; Joshi, Amit

    2013-01-01

    Externally modulated nanoparticles comprise a rapidly advancing class of cancer nanotherapeutics, which combine the favorable tumor accumulation of nanoparticles, with external spatio-temporal control on therapy delivery via optical, magnetic, or ultrasound modalities. The local control on therapy enables higher tumor treatment efficacy, while simultaneously reducing off-target effects. The nanoparticle interactions with external fields have an additional advantage of frequently generating an imaging signal, and thus such agents provide theranostic (both diagnostic and therapeutic) capabilities. In this review, we classify the emerging externally modulated theranostic nanoparticles according to the mode of external control and describe the physiochemical mechanisms underlying the external control of therapy, and illustrate the major embodiments of nanoparticles in each class with proven biological efficacy: (I) electromagnetic radiation in visible and near-infrared range is being exploited for gold based and carbon nanostructures with tunable surface plasmon resonance (SPR) for imaging and photothermal therapy (PTT) of cancer, photochemistry based manipulations are employed for light sensitive liposomes and porphyrin based nanoparticles; (II) Magnetic field based manipulations are being developed for iron-oxide based nanostructures for magnetic resonance imaging (MRI) and magnetothermal therapy; (III) ultrasound based methods are primarily being employed to increase delivery of conventional drugs and nanotherapeutics to tumor sites. PMID:24834381

  8. OH Module Assembly Stand

    SciTech Connect

    Bolan, P.J.; /Fermilab

    1990-10-16

    There is an OR module assembly stand in use at IB4. This design has been approved by safety, as presented by Mike Foley, and has been successfully used. Another one is needed at the D-zero assembly building, but some modifications need to be made. This report will show that the new modified design is at least as strong, if not stronger, than the older IB4 design in every aspect. Since the weight distribution of the OR modules on the sling is indeterminate, this report compares three cases of support for the entire assembly: the lowest two beams only, the lowest four beams only, and all six beams. In each of these cases, the new design is stronger than the old design in maximum allowable weight. The ability of the the cradle to support the weight is also shown. For all of the failure conditions except for two, the cradle is stronger than the beams that it supports. In the two excepted situations, the calculated limit of the cradle is less than the beams it supports. This is because no credit is taken for the sling and strongback, which in reality will relieve much of the horizontal load.

  9. Electrically modulated magnetoelectric sensors

    NASA Astrophysics Data System (ADS)

    Hayes, P.; Salzer, S.; Reermann, J.; Yarar, E.; Röbisch, V.; Piorra, A.; Meyners, D.; Höft, M.; Knöchel, R.; Schmidt, G.; Quandt, E.

    2016-05-01

    Magnetoelectric thin film composites have demonstrated their potential to detect sub-pT magnetic fields if mechanical resonances (typically few hundred Hz to a few kHz) are utilized. At low frequencies (1-100 Hz), magnetic field-induced frequency conversion has enabled wideband measurements with resonance-enhanced sensitivities by using the nonlinear characteristics of the magnetostriction curve. Nevertheless, the modulation with a magnetic field with a frequency close to the mechanical resonance results in a number of drawbacks, which are, e.g., size and energy consumption of the sensor as well as potential crosstalk in sensor arrays. In this work, we demonstrate the feasibility of an electric frequency conversion of a magnetoelectric sensor which would overcome the drawbacks of magnetic frequency conversion. This magnetoelectric sensor consists of three functional layers: an exchange biased magnetostrictive multilayer showing a high piezomagnetic coefficient without applying a magnetic bias field, a non-linear piezoelectric actuation layer and a linear piezoelectric sensing layer. In this approach, the low frequency magnetic signal is shifted into the mechanical resonance of the sensor, while the electric modulation frequency is chosen to be either the difference or the sum of the resonance and the signal frequency. Using this electric frequency conversion, a limit of detection in the low nT/Hz1/2 range was shown for signals of low frequency.

  10. Mechanical passive logic module

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay; Caulfield, H. John

    2015-02-01

    Nothing from nothing gives simple simile, but something from nothing is an interesting and challenging task. Adolf Lohmann once proposed 'do nothing machine' in optics, which only copies input to output. Passive logic module (PALM) is a special type of 'do nothing machine' which can converts inputs into one of 16 possible binary outputs. This logic module is not like the conventional irreversible one. It is a simple type of reversible Turing machine. In this manuscript we discussed and demonstrated PALM using mechanical movement of plane mirrors. Also we discussed the theoretical model of micro electro mechanical system (MEMS) based PALM in this manuscript. It may have several valuable properties such as passive operation (no need for nonlinear elements as other logic device require) and modular logic (one device implementing any Boolean logic function with simple internal changes). The result is obtained from the demonstration by only looking up the output. No calculation is required to get the result. Not only that, PALM is a simple type of the famous 'billiard ball machine', which also discussed in this manuscript.

  11. Photodynamic immune modulation (PIM)

    NASA Astrophysics Data System (ADS)

    North, John R.; Hunt, David W. C.; Simkin, Guillermo O.; Ratkay, Leslie G.; Chan, Agnes H.; Lui, Harvey; Levy, Julia G.

    1999-09-01

    Photodynamic Therapy (PDT) is accepted for treatment of superficial and lumen-occluding tumors in regions accessible to activating light and is now known to be effective in closure of choroidal neovasculature in Age Related Macular Degeneration. PDT utilizes light absorbing drugs (photosensitizers) that generate the localized formation of reactive oxygen species after light exposure. In a number of systems, PDT has immunomodulatory effects; Photodynamic Immune Modulation (PIM). Using low- intensity photodynamic regimens applied over a large body surface area, progression of mouse autoimmune disease could be inhibited. Further, this treatment strongly inhibited the immunologically- medicated contact hypersensitivity response to topically applied chemical haptens. Immune modulation appears to result from selective targeting of activated T lymphocytes and reduction in immunostimulation by antigen presenting cells. Psoriasis, an immune-mediated skin condition, exhibits heightened epidermal cell proliferation, epidermal layer thickening and plaque formation at different body sites. In a recent clinical trial, approximately one-third of patients with psoriasis and arthritis symptoms (psoriatic arthritis) displayed a significant clinical improvement in several psoriasis-related parameters after four weekly whole-body PIM treatments with verteporfin. The safety profile was favorable. The capacity of PIM to influence other human immune disorders including rheumatoid arthritis is under extensive evaluation.

  12. Influence of SiO2/In2O3 film acoustical waveguide on the mode index of Ti:LiNbO3 optical waveguide in acousto-optical mode converter

    NASA Astrophysics Data System (ADS)

    Lin, Hang-you; Ning, Ji-ping; Geng, Fan

    2004-04-01

    TE/TM mode converter is a key element of integrated acoustooptical tunable filter (AOTF). Employing SiO2/In2O3 film as acoustical waveguide can suppress sidelobes effectively and simplify fabrication technique in integrated quasi-collinear AOTF. In this report, the eigenvalue equation and the field solution of such configuration has been obtained by using modified Wenzel-Kramers-Brillouin (WKB) method. The results are compared with those by using vector finite element method (VFEM). When the optical waveguides are covered by such oxide film, the difference of mode indices of both polarizations and the effective propagation velocity of surface acoustical wave (SAW) will decrease, and these decreases lead the shift of optical wavelength, which mainly results in the change of the former.

  13. Documentation and solar cell modules

    NASA Astrophysics Data System (ADS)

    1985-03-01

    The Solarex Block V Group II module is a large frameless module intended for installation in a larger panel framework for use in intermediate to large size power system arrays. The module is a large one, based on a 0.125-inch thick tempered glass superstrate, containing 117 square cells, each one 10 cm on a side, arranged in a 13 series 9 parallel matrix. The design peak power at 25 C is in the 135-140 watt range. The module has a novel back sheet comprising a laminate of Tedlar, Mylar and a modified polyethylene. The Solarex Block V Group II module, designated Model C-120-10A, passed the JPL Block V qualification tests. A number of cracks were observed in cells in he two modules which underwent 200 thermal cycles, but the peak power change was less than 2% in each case.

  14. Reliability Research for Photovoltaic Modules

    NASA Technical Reports Server (NTRS)

    Ross, Ronald J., Jr.

    1986-01-01

    Report describes research approach used to improve reliability of photovoltaic modules. Aimed at raising useful module lifetime to 20 to 30 years. Development of cost-effective solutions to module-lifetime problem requires compromises between degradation rates, failure rates, and lifetimes, on one hand, and costs of initial manufacture, maintenance, and lost energy, on other hand. Life-cycle costing integrates disparate economic terms, allowing cost effectiveness to be quantified, allowing comparison of different design alternatives.

  15. Q-switching and mode-locking in a diode-pumped frequency-doubled Nd : YAG laser

    SciTech Connect

    Donin, Valerii I; Yakovin, Dmitrii V; Gribanov, A V

    2012-02-28

    A new method for obtaining Q-switching simultaneously with mode-locking using one travelling-wave acousto-optic modulator in a frequency-doubled Nd : YAG laser cavity is described. Further shortening of output laser pulses (from 40 to 3.25 ps) is achieved by forming a Kerr lens in the frequency-doubling crystal. At an average power of {approx} 2 W and a Q-switching rate of 2 kHz, the peak power of the stably operating reached {approx} 50 MW.

  16. Threshold of stimulated Brillouin scattering by use of a solar pumped laser.

    PubMed

    Naftali, Nir; Benmair, Ruth M J; Pe'er, Idit; Yogev, Ammon

    2002-06-20

    What is to our knowledge the first stimulated Brillouin scattering experiment using a high-power low-gain solar pumped laser is presented. A threshold reflectivity of 0.23% was reached when a peak power of 20.7 kW was used at 7.6 GHz. A cw solar pumped laser was Q-switched with an acousto-optic modulator, and the bandwidth was narrowed with an intracavity etalon. A high polarization ratio (>99.4%) was achieved by use of an intracavity configuration. Higher reflectivity values were limited because of the lack of availability of optical switches. PMID:12078683

  17. Tetravalent chromium (Cr(4+)) as laser-active ion for tunable solid-state lasers

    NASA Technical Reports Server (NTRS)

    Seas, A.; Petricevic, V.; Alfano, Robert R.

    1992-01-01

    Generation of femtosecond pulses from a continuous-wave mode-locked chromium-doped forsterite (Cr(4+):Mg2SiO4) laser has been accomplished. The forsterite laser was actively mode-locked using an acousto-optic modulator operating at 78 MHz with two Brewster high-dispersion glass prisms for intra-cavity chirp compensation. Transform-limited sub-100-fs pulses were routinely generated in the TEM(sub 00) mode with 85 mW of continuous power (with 1 percent output coupler), tunable over 1230-1280 nm. The shortest pulses of 60-fs pulsewidth were measured.

  18. [Advance in imaging spectropolarimeter].

    PubMed

    Wang, Xin-quan; Xiangli, Bin; Huang, Min; Hu, Liang; Zhou, Jin-song; Jing, Juan-juan

    2011-07-01

    Imaging spectropolarimeter (ISP) is a type of novel photoelectric sensor which integrated the functions of imaging, spectrometry and polarimetry. In the present paper, the concept of the ISP is introduced, and the advances in ISP at home and abroad in recent years is reviewed. The principles of ISPs based on novel devices, such as acousto-optic tunable filter (AOTF) and liquid crystal tunable filter (LCTF), are illustrated. In addition, the principles of ISPs developed by adding polarized components to the dispersing-type imaging spectrometer, spatially modulated Fourier transform imaging spectrometer, and computer tomography imaging spectrometer are introduced. Moreover, the trends of ISP are discussed too. PMID:21942063

  19. Homodyne measurement of the average photon number

    NASA Astrophysics Data System (ADS)

    Webb, J. G.; Ralph, T. C.; Huntington, E. H.

    2006-03-01

    We describe a scheme for measurement of the mean photon flux at an arbitrary optical sideband frequency using homodyne detection. Experimental implementation of the technique requires an acousto-optic modulator in addition to the homodyne detector, and does not require phase locking. The technique exhibits polarization and frequency and spatial mode selectivity, as well as much improved speed, resolution, and dynamic range when compared to linear photodetectors and avalanche photodiodes, with potential application to quantum-state tomography and information encoding using an optical frequency basis. Experimental data also support a quantum-mechanical description of vacuum noise.

  20. Lunar Infrared Spectrometer (LIS) for Luna-Resurs and Luna-Glob missions

    NASA Astrophysics Data System (ADS)

    Korablev, O.; Ivanov, A.; Mantsevich, S.; Kiselev, A.; Vyazovetskiy, N.; Fedorova, A.; Evdokimova, N.; Stepanov, A.; Titov, A.; Kalinnikov, Y.

    2012-09-01

    Lunar Infrared Spectrometer (LIS) is an experiment onboard Luna-Glob (launch in 2015) and Luna- Resurs (launch in 2017) Russian surface missions. The experiment is dedicated to the studies of mineralogy of the lunar regolith in the vicinity of the lander. The instrument is mounted on the mechanic arm of landing module in the field of view (45°) of stereo TV camera. LIS will provide measurements of selected surface region in the spectral range of 1.15-3.3 μm. The electrically commanded acousto-optic filter scans sequentially at a desired sampling, with random access, over the entire spectral range.