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Sample records for 2-micron laser transmitter

  1. 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Bai, Yingxin; Yu, Jirong

    2009-01-01

    Carbon dioxide (CO2) has been recognized as one of the most important greenhouse gases. It is essential for the study of global warming to accurately measure the CO2 concentration in the atmosphere and continuously record its variation. A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed in NASA Langley Research Center. This laser system is capable of making a vertical profiling of CO2 from ground and column measurement of CO2 from air and space-borne platform. The transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. A Ho:YLF laser operating in the range of 2.05 micrometers can be tuned over several characteristic lines of CO2 absorption. Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of CO2 with a repetition rate of 5 Hz and pulse energy of 75 mJ. For coherent detection, high repetition rate is required for speckle averaging to obtain highly precise measurements. However, a diode pumped Ho:Tm:YLF laser can not operate in high repetition rate due to the large heat loading and up-conversion. A Tm:fiber laser pumped Ho:YLF laser with low heat loading can operate in high repetition rate. A theoretical model has been established to simulate the performance of Tm:fiber laser pumped Ho:YLF lasers. For continuous wave (CW) operation, high pump intensity with small beam

  2. Development of a Pulsed 2-micron Laser Transmitter for CO2 Sensing from Space

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Yu, Jirong; Bai, Yingxin; Petros, Mulugeta; Menzies, Robert T.

    2011-01-01

    NASA Langley Research Center (LaRC), in collaboration with NASA Jet Propulsion Laboratory (JPL), is engaged in the development and demonstration of a highly efficient, versatile, 2-micron pulsed laser that can be used in a pulsed Differential Absorption Lidar (DIAL)/Integrated Path Differential Absorption (IPDA) instrument to make precise, high-resolution CO2 measurements to investigate sources, sinks, and fluxes of CO2. This laser transmitter will feature performance characteristics needed for an ASCENDS system that will be capable of delivering the CO2 measurement precision required by the Earth Science Decadal Survey (DS).

  3. High Repetition Rate Pulsed 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

    NASA Technical Reports Server (NTRS)

    Singh, Uprendra N.; Bai, Yingxin; Yu, Jirong; Petros, Mulugeta; Petzar, Paul J.; Trieu, Bo C.; Lee, Hyung

    2009-01-01

    A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed at NASA Langley Research Center. Such a laser transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of approximately 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. The measured standard deviation of the laser frequency jitter is about 3 MHz.

  4. Pulsed 2-micron Laser Transmitter For Carbon Dioxide Sensing From Space

    NASA Astrophysics Data System (ADS)

    Singh, U. N.; Yu, J.; Bai, Y.; Petros, M.

    2011-12-01

    Carbon dioxide (CO2) has been recognized as one of the most important greenhouse gases. It is essential for the study of global warming to accurately measure the CO2 concentration in the atmosphere and continuously record its variation. Studies of the carbon cycle are limited by the tools available to precisely measure CO2 concentrations by remote sensing. Active sensing, using the Integrated Path Differential Absorption (IPDA) approach, permits measurements day and night, at all latitudes and seasons. The development of a high pulse energy 2-μm laser transmitter for high-precision CO2 measurements from space leverages years of NASA investment in solid-state laser technology. Under NASA Laser Risk Reduction Program, funded by Earth Science Technology Office, researchers at NASA Langley Research Center developed an injection seeded, high repetition rate, Q-switched Ho:YLF laser transmitter for CO2 Differential Absorption Lidar/IPDA (profile/column) measurements from ground and airborne platforms. This master-slave laser system has high optical-to-optical efficiency and seeding success rate. NASA LaRC's 2-micron pulsed laser transmitter possesses advantages over current passive and CW active sensors. First, the pulsed format provides a built-in means for determining range to the scattering target and effectively filtering out the scattering from thin clouds and aerosols, thus eliminating a source of measurement bias. Second, by concentrating the laser energy into a pulse, sufficient backscatter signal strength can be obtained from aerosol scattering rather than relying on a hard target at a known distance. Third, the absorption line at the 2.05 μm band is ideally suited for the CO2 concentration measurement. In particular, the weighting function of 2 μm is optimum for measurement in the lower troposphere where the sources and sinks of CO2 are located. The planned laser transmitter development will lead to a Tm:Fiber pumped Ho:YLF laser transmitter capable of

  5. High Energy 2-Micron Solid-State Laser Transmitter for NASA's Airborne CO2 Measurements

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Bai, Yingxin

    2012-01-01

    A 2-micron pulsed, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric CO2 concentration measurements via direct detection method is being developed at NASA Langley Research Center. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capability by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement.

  6. Advances in High Energy Solid-State 2-micron Laser Transmitter Development for Ground and Airborne Wind and CO2 Measurements

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Chen, Songsheng; Kavaya, Michael J.; Trieu, Bo; Bai, Yingxin; Petzar, Paul; Modlin, Edward A.; Koch, Grady; Beyon, Jeffrey

    2010-01-01

    Sustained research efforts at NASA Langley Research Center (LaRC) during last fifteen years have resulted in a significant advancement in 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurement from ground, air and space-borne platform. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar (DIAL) system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements.

  7. High Energy 2-micron Laser Developments

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Bai, Yingxin; Petzar, Paul J.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    This viewgraph presentation shows the development of 2-micron solid state lasers. The topics covered include: 1) Overview 2-micron solid state lasers; 2) Modeling and population inversion measurement; 3) Side pump oscillator; and 4) One Joule 2-m Laser.

  8. Solid-State 2-Micron Laser Transmitter Advancement for Wind and Carbon Dioxide Measurements From Ground, Airborne, and Space-Based Lidar Systems

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Kavaya, Michael J.; Koch, Grady; Yu, Jirong; Ismail, Syed

    2008-01-01

    NASA Langley Research Center has been developing 2-micron lidar technologies over a decade for wind measurements, utilizing coherent Doppler wind lidar technique and carbon dioxide measurements, utilizing Differential Absorption Lidar (DIAL) technique. Significant advancements have been made towards developing state-of-the-art technologies towards laser transmitters, detectors, and receiver systems. These efforts have led to the development of solid-state lasers with high pulse energy, tunablility, wavelength-stability, and double-pulsed operation. This paper will present a review of these technological developments along with examples of high resolution wind and high precision CO2 DIAL measurements in the atmosphere. Plans for the development of compact high power lasers for applications in airborne and future space platforms for wind and regional to global scale measurement of atmospheric CO2 will also be discussed.

  9. High Energy 2-Micron Laser Developments

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Bai, Yingxin; Petzar, Paul J.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    A master oscillator power amplifier, high energy Q-switched 2-micron laser system has been recently demonstrated. The laser and amplifiers are all designed in side-pumped rod configuration, pumped by back-cooled conductive packaged GaAlAs diode laser arrays. This 2-micron laser system provides nearly transform limited beam quality.

  10. 2 micron femtosecond fiber laser

    DOEpatents

    Liu, Jian; Wan, Peng; Yang, Lihmei

    2014-07-29

    Methods and systems for generating femtosecond fiber laser pulses are disclose, including generating a signal laser pulse from a seed laser oscillator; using a first amplifier stage comprising an input and an output, wherein the signal laser pulse is coupled into the input of the first stage amplifier and the output of the first amplifier stage emits an amplified and stretched signal laser pulse; using an amplifier chain comprising an input and an output, wherein the amplified and stretched signal laser pulse from the output of the first amplifier stage is coupled into the input of the amplifier chain and the output of the amplifier chain emits a further amplified, stretched signal laser pulse. Other embodiments are described and claimed.

  11. Injection Seeded/Phase-Conjugated 2-micron Laser System

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Yu, Jirong; Petros,M.; Petzar, Paul; Trieu, Bo; Lee, Hyung; Singh, U.; Leyva, V.; Shkunov, V.; Rockwell, D.; Betin, A.; Wang, J.

    2007-01-01

    For the first time, beam quality improvement of 2 micron laser using a fiber based phase conjugation mirror has been demonstrated. Single frequency operation is necessary to lower threshold. The reflectivity of PCM is approx. 50%.

  12. Narrow Line-width, High-energy, 2-micron Laser for Coherent Wind Lidar

    NASA Astrophysics Data System (ADS)

    Singh, U.; Yu, J.

    2 micron solid-state lasers are the primary choice for coherent Doppler wind detection. As wind lidars, they are used for wake vortex and clear air turbulence detection providing air transport safety. In addition, 2 micron lasers are one of the candidates for CO2 detection lidars. The rich CO2 absorption line around 2 micron, combined with the long upper state lifetime, has made Ho based 2 micron lasers a viable candidate for CO2 sensing DIAL instrument. As a transmitter for a coherent wind lidar, this laser has stringent spectral line width and beam quality requirements. The laser architecture is composed of a seed laser, a ring oscillator, and a double pass amplifier. The seed laser is a single longitudinal mode with a line width of 13 KHz. The 100mJ class oscillator is stretched to 3 meters to accommodate the line-width requirement without compromising the range resolution of the instrument. The amplifier is double passed to produce greater than 300mJ energy. This system is hardened for ground as well as airborne applications.

  13. A High Energy 2-microns Laser for Multiple Lidar Applications

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Singh, Upendra N.; Barnes, James C.; Barnes, Norman P.; Petros, Mulugeta

    2000-01-01

    Solid-state 2-microns laser has been receiving considerable interest because of its eye-safe property and efficient diode pump operation, It has potential for multiple lidar applications to detect water vapor. carbon dioxide and winds. In this paper, we describe a 2-microns double pulsed Ho:Tm:YLF laser and end-pumped amplifier system. A comprehensive theoretical model has been developed to aid the design and optimization of the laser performance. In a single Q-switched pulse operation the residual energy stored in the Tm atoms will be wasted. However, in a double pulses operation mode, the residual energy stored in the Tm atoms will repopulate the Ho atoms that were depleted by the extraction of the first Q-switched pulse. Thus. the Tin sensitized Ho:YLF laser provides a unique advantage in applications that require double pulse operation, such as Differential Absorption Lidar (DIAL). A total output energy of 146 mJ per pulse pair under Q-switch operation is achieved with as high as 4.8% optical to optical efficiency. Compared to a single pulse laser, 70% higher laser efficiency is realized. To obtain high energy while maintaining the high beam quality, a master-oscillator-power-amplifier 2-microns system is designed. We developed an end-pumped Ho:Tm:YLF disk amplifier. This amplifier uses two diode arrays as pump source. A non-imaging lens duct is used to couple the radiation from the laser diode arrays to the laser disk. Preliminary result shows that the efficiency of this laser can be as high as 3%, a factor of three increases over side-pump configuration. This high energy, highly efficient and high beam quality laser is a promising candidate for use in an efficient, multiple lidar applications.

  14. Coherent laser radar at 2 microns using solid-state lasers

    NASA Technical Reports Server (NTRS)

    Henderson, Sammy W.; Suni, Paul J. M.; Hale, Charley P.; Hannon, Stephen M.; Magee, James R.; Bruns, Dale L.; Yuen, Eric H.

    1993-01-01

    Coherent laser radar systems using 2-micron Tm- and Tm, Ho-doped solid-state lasers are useful for the remote range-resolved measurement of atmospheric winds, aerosol backscatter, and DIAL measurements of atmospheric water vapor and CO2 concentrations. Recent measurements made with a 2-micron coherent laser radar system, advances in the laser technology, and atmospheric propagation effects on 2-micron coherent lidar performance are described.

  15. Progress on High-Energy 2-micron Solid State Laser for NASA Space-Based Wind and Carbon Dioxide Measurements

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.

    2011-01-01

    Sustained research efforts at NASA Langley Research Center during last fifteen years have resulted in significant advancement of a 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurements from ground, air and space-borne platforms. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements.

  16. High Power Laser Diode Arrays for 2-Micron Solid State Coherent Lidars Applications

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron; Kavaya, Michael J.; Singh, Upendra; Sudesh, Vikas; Baker, Nathaniel

    2003-01-01

    Laser diode arrays are critical components of any diode-pumped solid state laser systems, constraining their performance and reliability. Laser diode arrays (LDAs) are used as the pump source for energizing the solid state lasing media to generate an intense coherent laser beam with a high spatial and spectral quality. The solid state laser design and the characteristics of its lasing materials define the operating wavelength, pulse duration, and power of the laser diodes. The pump requirements for high pulse energy 2-micron solid state lasers are substantially different from those of more widely used 1-micron lasers and in many aspects more challenging [1]. Furthermore, the reliability and lifetime demanded by many coherent lidar applications, such as global wind profiling from space and long-range clear air turbulence detection from aircraft, are beyond the capability of currently available LDAs. In addition to the need for more reliable LDAs with longer lifetime, further improvement in the operational parameters of high power quasi-cw LDAs, such as electrical efficiency, brightness, and duty cycle, are also necessary for developing cost-effective 2-micron coherent lidar systems for applications that impose stringent size, heat dissipation, and power constraints. Global wind sounding from space is one of such applications, which is the main driver for this work as part of NASA s Laser Risk Reduction Program. This paper discusses the current state of the 792 nm LDA technology and the technology areas being pursued toward improving their performance. The design and development of a unique characterization facility for addressing the specific issues associated with the LDAs for pumping 2-micron coherent lidar transmitters and identifying areas of technological improvement will be described. Finally, the results of measurements to date on various standard laser diode packages, as well as custom-designed packages with potentially longer lifetime, will be reported.

  17. Qualification Testing of Laser Diode Pump Arrays for a Space-Based 2-micron Coherent Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    The 2-micron thulium and holmium-based lasers being considered as the transmitter source for space-based coherent Doppler lidar require high power laser diode pump arrays operating in a long pulse regime of about 1 msec. Operating laser diode arrays over such long pulses drastically impact their useful lifetime due to the excessive localized heating and substantial pulse-to-pulse thermal cycling of their active regions. This paper describes the long pulse performance of laser diode arrays and their critical thermal characteristics. A viable approach is then offered that allows for determining the optimum operational parameters leading to the maximum attainable lifetime.

  18. Advanced 2-micron Solid-state Laser for Wind and CO2 Lidar Applications

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Bai, Yingxin; Petzar, Paul J.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.

    2006-01-01

    Significant advancements in the 2-micron laser development have been made recently. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar (DIAL) system for measuring atmospheric CO2 concentration profiles. The world record 2-micron laser energy is demonstrated with an oscillator and two amplifiers system. It generates more than one joule per pulse energy with excellent beam quality. Based on the successful demonstration of a fully conductive cooled oscillator by using heat pipe technology, an improved fully conductively cooled 2-micron amplifier was designed, manufactured and integrated. It virtually eliminates the running coolant to increase the overall system efficiency and reliability. In addition to technology development and demonstration, a compact and engineering hardened 2-micron laser is under development. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser is expected to be integrated to a lidar system and take field measurements. The recent achievements push forward the readiness of such a laser system for space lidar applications. This paper will review the developments of the state-of-the-art solid-state 2-micron laser.

  19. A Master-Oscillator-Power-Amplifier 2-micron Laser Using Fiber Phase-conjugate Mirror

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Bai, Yingxin; Shkunov, V.; Rockwell, D.; Betin, A.; Wang, J.; Petros, M.; Petzar, Paul; Trieu, Bo

    2007-01-01

    For the first time, a 2-micron master-oscillator-power-amplifier laser using a fiber based phase conjugation mirror has been demonstrated. The beam quality improvement and 56% of the PCM reflectivity have been achieved.

  20. Improving Lifetime of Quasi-CW Laser Diode Arrays for Pumping 2-Micron Solid State Lasers

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data on the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

  1. Developing high energy dissipative soliton fiber lasers at 2 micron

    PubMed Central

    Huang, Chongyuan; Wang, Cong; Shang, Wei; Yang, Nan; Tang, Yulong; Xu, Jianqiu

    2015-01-01

    While the recent discovered new mode-locking mechanism - dissipative soliton - has successfully improved the pulse energy of 1 μm and 1.5 μm fiber lasers to tens of nanojoules, it is still hard to scale the pulse energy at 2 μm due to the anomalous dispersion of the gain fiber. After analyzing the intracavity pulse dynamics, we propose that the gain fiber should be condensed to short lengths in order to generate high energy pulse at 2 μm. Numerical simulation predicts the existence of stable 2 μm dissipative soliton solutions with pulse energy over 10 nJ, comparable to that achieved in the 1 μm and 1.5 μm regimes. Experimental operation confirms the validity of the proposal. These results will advance our understanding of mode-locked fiber lasers at different wavelengths and lay an important step in achieving high energy ultrafast laser pulses from anomalous dispersion gain media. PMID:26348563

  2. Single-Frequency Narrow Linewidth 2 Micron Fiber Laser

    NASA Technical Reports Server (NTRS)

    Jiang, Shibin (Inventor); Spiegelberg, Christine (Inventor); Luo, Tao (Inventor)

    2006-01-01

    A compact single frequency, single-mode 2 .mu.m fiber laser with narrow linewidth, <100 kHz and preferably <100 kHz, is formed with a low phonon energy glass doped with triply ionized rare-earth thulium and/or holmium oxide and fiber gratings formed in sections of passive silica fiber and fused thereto. Formation of the gratings in passive silica fiber both facilitates splicing to other optical components and reduces noise thus improving linewidth. An increased doping concentration of 0.5 to 15 wt. % for thulium, holmium or mixtures thereof produces adequate gain, hence output power levels for fiber lengths less than 5 cm and preferably less than 3 cm to enable single-frequency operation.

  3. One-Joule-per-Pulse Q-Switched 2-micron Solid State Laser

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Trieu, Bo C.; Modlin, Ed A.; Singh, Upendra N.; Kavaya, Michael J.; Chen, Songsheng; Bai, Yingxin; Petzar, Pual J.; Petros, Mulugeta

    2005-01-01

    Q-switched output of 1.1 J per pulse at 2-micron wavelength has been achieved in a diode pumped Ho:Tm:LuLF laser using a side-pumped rod configuration in a Master-Oscillator-Power-Amplifier (MOPA) architecture. This is the first time that a 2-micron laser has broken the Joule per pulse barrier for Q-switched operation. The total system efficiency reaches 5% and 6.2% for single and double pulse operation, respectively. The system produces excellent 1.4 times of transform limited beam quality.

  4. Generating 2 micron continuous-wave ytterbium-doped fiber laser-based optical parametric effect

    NASA Astrophysics Data System (ADS)

    Paul, M. C.; Latiff, A. A.; Hisyam, M. B.; Rusdi, M. F. M.; Harun, S. W.

    2016-10-01

    We report an efficient method for generating a 2 micron laser based on an optical parametric oscillator (OPO). It uses a long piece of a newly developed double-clad ytterbium-doped fiber (YDF), which is obtained by doping multi-elements of ZrO2, CeO2 and CaO in a phospho-alumina-silica glass as a gain medium. The efficient 2 micron laser generation is successful due to the presence of partially crystalline Yb-doped ZrO2 nano-particles that serve as a nonlinear material in a linear cavity configuration and high watt-level pump power. Stable self-wavelength double lasing at 2122 nm with an efficiency of 7.15% is successfully recorded. At a maximum pump power of 4.1 W, the output power is about 201 mW.

  5. Self-Calibration and Laser Energy Monitor Validations for a Double-Pulsed 2-Micron CO2 Integrated Path Differential Absorption Lidar Application

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Singh, Upendra N.; Petros, Mulugeta; Remus, Ruben; Yu, Jirong

    2015-01-01

    Double-pulsed 2-micron integrated path differential absorption (IPDA) lidar is well suited for atmospheric CO2 remote sensing. The IPDA lidar technique relies on wavelength differentiation between strong and weak absorbing features of the gas normalized to the transmitted energy. In the double-pulse case, each shot of the transmitter produces two successive laser pulses separated by a short interval. Calibration of the transmitted pulse energies is required for accurate CO2 measurement. Design and calibration of a 2-micron double-pulse laser energy monitor is presented. The design is based on an InGaAs pin quantum detector. A high-speed photo-electromagnetic quantum detector was used for laser-pulse profile verification. Both quantum detectors were calibrated using a reference pyroelectric thermal detector. Calibration included comparing the three detection technologies in the single-pulsed mode, then comparing the quantum detectors in the double-pulsed mode. In addition, a self-calibration feature of the 2-micron IPDA lidar is presented. This feature allows one to monitor the transmitted laser energy, through residual scattering, with a single detection channel. This reduces the CO2 measurement uncertainty. IPDA lidar ground validation for CO2 measurement is presented for both calibrated energy monitor and self-calibration options. The calibrated energy monitor resulted in a lower CO2 measurement bias, while self-calibration resulted in a better CO2 temporal profiling when compared to the in situ sensor.

  6. Transmittance and reflectance of crystalline quartz and highand low-water content fused silica from 2 microns to 1 mm

    NASA Technical Reports Server (NTRS)

    Heaney, J. B.; Stewart, K. P.; Hass, G.

    1983-01-01

    The transmittances and reflectances of cultured crystalline quartz, Suprasil, Suprasil W, and Infrasil were compared over the wavelength region from 2 to 1000 microns. The high-water content of Suprasil and the low-water content of cultured crystalline quartz, Suprasil W, and Infrasil were determined by their transmittances measured at 2.73 microns where water content causes high absorption in optical materials. The fact that the fused silicas, both with high- and low-water content, had identical far-IR transmittances and that their transmittances were greatly inferior to that of crystalline quartz led to the conclusion that their inferior transmittance is due to their amorphous structure and not to their water content.

  7. Laser Transmitter Aims At Laser Beacon

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Lesh, James R.

    1993-01-01

    Transmitter part of developmental optical communication system. Compact, lightweight, partially-self-aiming laser transmitter built to verify some capabilities of developmental free-space optical communication system. Design capable of providing 0.5 Mbps data return over range equal to Moon-Earth distance. Breadboard of transmitting terminal constructed and tested in laboratory. Prototype transmitter includes receiving circuitry that keeps it aimed at beacon, once brought into initial alignment within about 1.7 degrees of line of sight to beacon.

  8. Compact Quantum Cascade Laser Transmitter

    SciTech Connect

    Anheier, Norman C.; Hatchell, Brian K.; Gervais, Kevin L.; Wojcik, Michael D.; Krishnaswami, Kannan; Bernacki, Bruce E.

    2009-04-01

    ): In this paper we present design considerations, thermal and optical modeling results, and device performance for a ruggedized, compact laser transmitter that utilizes a room temperature quantum cascade (QC) laser source. The QC laser transmitter is intended for portable mid-infrared (3-12 µm) spectroscopy applications, where the atmospheric transmission window is relatively free of water vapor interference and where the molecular rotational vibration absorption features can be used to detect and uniquely identify chemical compounds of interest. Initial QC laser-based sensor development efforts were constrained by the complications of cryogenic operation. However, improvements in both QC laser designs and fabrication processes have provided room-temperature devices that now enable significant miniaturization and integration potential for national security, environmental monitoring, atmospheric science, and industrial safety applications.

  9. The Geoscience Laser Altimeter System Laser Transmitter

    NASA Technical Reports Server (NTRS)

    Afzal, R. S.; Dallas, J. L.; Yu, A. W.; Mamakos, W. A.; Lukemire, A.; Schroeder, B.; Malak, A.

    2000-01-01

    The Geoscience Laser Altimeter System (GLAS), scheduled to launch in 2001, is a laser altimeter and lidar for tile Earth Observing System's (EOS) ICESat mission. The laser transmitter requirements, design and qualification test results for this space- based remote sensing instrument are presented.

  10. Validar: A Testbed for Advanced 2-Micron Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.; Petros, Mulugeta; Barnes, Bruce W.; Beyon, Jeffrey Y.; Amzajerdian, Farzin; Yu, Jirong; Kavaya, Michael J.; Singh, Upendra N.

    2004-01-01

    High-energy 2-microns lasers have been incorporated in a breadboard coherent Doppler lidar to test component technologies and explore applications for remote sensing of the atmosphere. Design of the lidar is presented including aspects in the laser transmitter, receiver, photodetector, and signal processing. Sample data is presented on wind profiling and CO2 concentration measurements.

  11. Theoretical simulation of a 2 micron airborne solid state laser anemometer

    NASA Technical Reports Server (NTRS)

    Imbert, Beatrice; Cariou, Jean-Pierre

    1992-01-01

    In the near future, military aircraft will need to know precisely their true airspeed in order to optimize flight conditions. In comparison with classical anemometer probes, an airborne Doppler lidar allows measurement of the air velocity without influence from aircraft aerodynamic disturbance. While several demonstration systems of heterodyne detection using a CO2 laser have been reported, improvements in the technology of solid state lasers have recently opened up the possibility that these devices can be used as an alternative to CO2 laser systems. In particular, a diode pumped Tm:Ho:YAG laser allows a reliable compact airborne system with an eye safe wavelength (lambda = 2.09 microns) to be achieved. The theoretical study of performances of a coherent lidar using a solid state diode pumped Tm:Ho:YAG laser, caled SALSA, for measuring aircraft airspeed relative to atmospheric aerosols is described. A computer simulation was developed in order to modelize the Doppler anemometer in the function of atmospheric propagation and optical design. A clever analysis of the power budget on the detector area allows optical characteristic parameters of the system to be calculated, and then it can be used to predict performances of the Doppler system. Estimating signal to noise ratios (SNR) and heterodyne efficiency provides the available energy of speed measurement as well as a useful measurement of the alignment of the backscattered and reference fields on the detector.

  12. Solid-State, High Energy 2-Micron Laser Development for Space-Based Remote Sensing

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.

    2010-01-01

    Lidar (light detection and ranging) remote sensing enjoys the advantages of excellent vertical and horizontal resolution; pointing capability; a signal source independent from natural light; and control and knowledge of transmitted wavelength, pulse shape, and polarization and received polarization. Lidar in space is an emerging technology now being developing to fit applications where passive sensors cannot meet current measurement requirements. Technical requirements for space lidar are more demanding than for ground-based or airborne systems. Perhaps the most distinguishing characteristics of space lidars are the environmental requirements. Space lidar systems must be specially designed to survive the mechanical vibration loads of launch and operate in the vacuum of space where exposure to ionizing radiation limits the electronic components available. Finally, space lidars must be designed to be highly reliable because they must operate without the need for repair or adjustment. Lifetime requirements tend to be important drivers of the overall system design. The maturity of the required technologies is a key to the development of any space lidar system. NASA entered a new era in the 1990 s with the approval of several space-based remote sensing missions employing laser radar (lidar) techniques. Following the steps of passive remote sensing and then active radar remote sensing, lidar sensors were a logical next step, providing independence from natural light sources, and better spatial resolution and smaller sensor size than radar sensors. The shorter electromagnetic wavelengths of laser light also allowed signal reflectance from air molecules and aerosol particles. The smaller receiver apertures allowed the concept of scanning the sensor field of view. However, technical problems with several space-based lidar missions during that decade led to concern at NASA about the risk of lidar missions. An external panel was convened to make recommendations to NASA. Their

  13. The Lunar Orbiter Laser Altimeter (LOLA) Laser Transmitter

    NASA Technical Reports Server (NTRS)

    Yu, Anthony W.; Novo-Gradac, Anne Marie; Shaw, George B.; Unger, Glenn; Lukemire, Alan

    2008-01-01

    We present the final configuration of the space flight laser transmitter as delivered to the LOLA instrument. The laser consists of two oscillators with co-aligned outputs on a single bench, each capable of providing one billion plus shots.

  14. Laser Transmitter for the Lunar Orbit Laser Altimeter (LOLA) Instrument

    NASA Technical Reports Server (NTRS)

    Yu, Anthony W.; Novo-Gradac, Anne-Marie; Shaw, George B.; Li, Steven X.; Krebs, Danny C.; Ramos-Izquierdo, Luis A.; Unger, Glenn; Lukemire, Alan

    2008-01-01

    We present the final configuration of the space flight laser transmitter as delivered to the LOLA instrument. The laser consists of two oscillators on a single bench, each capable of providing one billion plus shots.

  15. 2-Micron Coherent Doppler Lidar Instrument Advancements for Tropospheric Wind Measurement

    NASA Technical Reports Server (NTRS)

    Petros, Mulugeta; Singh, U. N.; Yu, J.; Kavaya, M. J.; Koch, G.

    2014-01-01

    Knowledge derived from global tropospheric wind measurement is an important constituent of our overall understanding of climate behavior [1]. Accurate weather prediction saves lives and protects properties from destructions. High-energy 2-micron laser is the transmitter of choice for coherent Doppler wind detection. In addition to the eye-safety, the wavelength of the transmitter suitably matches the aerosol size in the lower troposphere. Although the technology of the 2-micron laser has been maturing steadily, lidar derived wind data is still a void in the global weather database. In the last decade, researchers at NASA Langley Research Center (LaRC) have been engaged in this endeavor, contributing to the scientific database of 2-micron lidar transmitters. As part of this effort, an in depth analysis of the physics involved in the workings of the Ho: Tm laser systems have been published. In the last few years, we have demonstrated lidar transmitter with over1Joule output energy. In addition, a large body of work has been done in characterizing new laser materials and unique crystal configurations to enhance the efficiency and output energy of the 2-micron laser systems. At present 2-micron lidar systems are measuring wind from both ground and airborne platforms. This paper will provide an overview of the advancements made in recent years and the technology maturity levels attained.

  16. Laser Transmitter Design for the Geoscience Laser Altimeter System

    NASA Technical Reports Server (NTRS)

    Afzal, R. S.; Yu, A. W.; Mamakos, W.; Lukemire, A.; Dallas, J. L.; Schroeder, B.; Green, J. W.

    1998-01-01

    NASA is embarking on a new era of laser remote sensing instruments from space. This paper focuses specifically on the laser technology involved in one of the present NASA missions. The Geoscience Laser Altimeter System (GLAS) scheduled to launch in 2001 is a laser altimeter and lidar for the Earth Observing System's (EOS) ICESat mission. The laser transmitter for this space-based remote sensing instrument is discussed in the context of the mission requirements.

  17. Flight-qualification of a wideband laser diode transmitter module

    NASA Technical Reports Server (NTRS)

    Holcomb, Terry L.; Mecherle, G. S.

    1992-01-01

    A diffraction-limited laser diode transmitter module suitable for wideband direct detection laser communication is described. The transmitter module incorporates a high power semiconductor diode laser, collimating lens, thermal control, and driver circuit in a hermetic enclosure. The module has undergone environmental testing which demonstrates its suitability for space application, and accelerated lifetesting of the laser diode suggests an operational lifetime of nearly ten years.

  18. Space qualified laser transmitter for NASA's ICESat-2 mission

    NASA Astrophysics Data System (ADS)

    Sawruk, Nicholas W.; Stephen, Mark A.; Litvinovitch, Slava; Edelman, Joel E.; Albert, Michael M.; Edwards, Ryan E.; Culpepper, Charles F.; Rudd, William J.; Fakhoury, Elias; Hovis, Floyd E.

    2013-03-01

    Fibertek has developed an environmentally hardened Technology Readiness Level-6 laser transmitter system for the NASA Ice, Cloud and land Elevation Satellite-2 (ICESat-2). The laser transmitter generates over 9 W of 532 nm output with a pulse repetition rate of 10kHz and a FWHM pulse width of < 1.5 ns with an expected lifetime of > 1 trillion shots. This paper presents the results of the Structural, Thermal and Optical analysis, details on the NASA General Environmental Verification Specification testing requirements, and the success of the laser transmitter performance through vibration and thermal vacuum testing.

  19. Recent Development of Sb-based Phototransistors in the 0.9- to 2.2-microns Wavelength Range for Applications to Laser Remote Sensing

    NASA Technical Reports Server (NTRS)

    Abedin, M. Nurul; Refaat, Tamer F.; Sulima, Oleg V.; Singh, Upendra N.

    2006-01-01

    We have investigated commercially available photodiodes and also recent developed Sb-based phototransistors in order to compare their performances for applications to laser remote sensing. A custom-designed phototransistor in the 0.9- to 2.2-microns wavelength range has been developed at AstroPower and characterized at NASA Langley's Detector Characterization Laboratory. The phototransistor's performance greatly exceeds the previously reported results at this wavelength range in the literature. The detector testing included spectral response, dark current and noise measurements. Spectral response measurements were carried out to determine the responsivity at 2-microns wavelength at different bias voltages with fixed temperature; and different temperatures with fixed bias voltage. Current versus voltage characteristics were also recorded at different temperatures. Results show high responsivity of 2650 A/W corresponding to an internal gain of three orders of magnitude, and high detectivity (D*) of 3.9x10(exp 11) cm.Hz(exp 1/2)/W that is equivalent to a noise-equivalent-power of 4.6x10(exp -14) W/Hz(exp 1/2) (-4.0 V @ -20 C) with a light collecting area diameter of 200-microns. It appears that this recently developed 2-micron phototransistor's performances such as responsivity, detectivity, and gain are improved significantly as compared to the previously published APD and SAM APD using similar materials. These detectors are considered as phototransistors based-on their structures and performance characteristics and may have great potential for high sensitivity differential absorption lidar (DIAL) measurements of carbon dioxide and water vapor at 2.05-microns and 1.9-microns, respectively.

  20. Development of 2-micron nonlinear frequency conversion laser system and tissue interaction monitoring using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Kim, Bongkyun; Ahn, Jin-Chul; Chung, Phil-Sang; Kim, Dae Yu

    2016-03-01

    We report on development of optical parametric oscillator (OPO) based mid-infrared laser system, which utilizes periodically poled nonlinear crystal that was pumped by near-infrared (NIR) laser. We have obtained 8 W of mid-infrared average output at the injection current of 20A from a quasi-phase-matched OPO using external cavity configuration. The laser tissue ablation efficiency was investigated which is substantially affected by several parameters such as, optical fluence rate, wavelength of the laser source and the optical properties of target tissue. Wavelength and radiant exposure dependent tissue ablation dimension were quantified by using SD-OCT (spectral domain optical coherence tomography) and the ablation efficiency was compared to that of non-converted NIR- laser system.

  1. Laterally Coupled Distributed-Feedback GaSb-Based Diode Lasers for Atmospheric Gas Detection at 2 Microns

    NASA Technical Reports Server (NTRS)

    Briggs, Ryan M.; Frez, Clifford; Ksendzov, Alexander; Franz, Kale J.; Bagheri, Mahmood; Forouhar, Siamak

    2012-01-01

    We demonstrate single-mode laterally coupled distributed-feedback diode lasers at 2.05 microns employing low-loss etched gratings. Single-facet CW output exceeds 50 mW near room temperature with linewidth below 1 MHz over 10-ms observation times

  2. Advanced quantum cascade laser transmitter architectures and infrared photonics development

    SciTech Connect

    Anheier, Norman C.; Allen, Paul J.; Myers, Tanya L.

    2004-08-01

    Quantum cascade lasers (QCLs) provide a viable infrared laser source for a new class of laser transmitters capable of meeting the performance requirements for a variety of national security and civilian applications. The high output power, small size, and superb stability and modulation characteristics of QCLs make them amenable for integration as transmitters into ultra-sensitive, ultra-selective point sampling and remote short-range chemical sensors. This paper reports on the current development in infrared photonics that provides a pathway for QCL transmitter miniaturization. This research has produced infrared waveguide-based optical components in chalcogenide glass using both direct-laser writing and holographic exposure techniques. We discuss here the design and fabrication concepts and capabilities required to produce integrated waveguides, waveguide couplers, and other photonic devices.

  3. Watt-level supercontinuum generation in As2Se3 fibers pumped by a 2-micron random fiber laser

    NASA Astrophysics Data System (ADS)

    Tang, Yulong; Li, Feng; Xu, Jianqiu

    2016-05-01

    Chalcogenide fibers are good candidates for generating supercontinuum (SC) radiation due to their large nonlinear refractive indices and high mid-infrared transmission, but their low damage thresholds hamper the SC power scaling, thereby limiting the ultimately achieved SC brightness. Here, we report an As2Se3 fiber SC system pumped by a novel random Q-switched 2 μm Tm3+ fiber laser. The maximum SC output power is 1.09 W with slope efficiency of 24%, and the SC spans from ~1980 to ~2500 nm with a spectral width of ~500 nm at the  -20 dB points. The spectral power density is ~2 mW nm-1. To the best of our knowledge, this is the highest power and spectral density SC emission ever achieved in chalcogenide fibers.

  4. Airborne Measurements of Atmospheric Methane Using Pulsed Laser Transmitters

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Riris, Haris; Wu, Stewart; Gonzalez, Brayler; Rodriguez, Michael; Hasselbrack, William; Fahey, Molly; Yu, Anthony; Stephen, Mark; Mao, Jianping; Kawa, Stephan

    2016-01-01

    Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. At NASA Goddard Space Flight Center (GSFC) we have been developing a laser-based technology needed to remotely measure CH4 from orbit. We report on our development effort for the methane lidar, especially on our laser transmitters and recent airborne demonstration. Our lidar transmitter is based on an optical parametric process to generate near infrared laser radiation at 1651 nanometers, coincident with a CH4 absorption. In an airborne flight campaign in the fall of 2015, we tested two kinds of laser transmitters --- an optical parametric amplifier (OPA) and an optical parametric oscillator (OPO). The output wavelength of the lasers was rapidly tuned over the CH4 absorption by tuning the seed laser to sample the CH4 absorption line at several wavelengths. This approach uses the same Integrated Path Differential Absorption (IPDA) technique we have used for our CO2 lidar for ASCENDS. The two laser transmitters were successfully operated in the NASAs DC-8 aircraft, measuring methane from 3 to 13 kilometers with high precision.

  5. In-Flight Performance of the Mercury Laser Altimeter Laser Transmitter

    NASA Technical Reports Server (NTRS)

    Yu, Anthony W.; Sun, Xiaoli; Li, Steven X.; Cavanaugh, John F.; Neumann, Gregory A.

    2014-01-01

    The Mercury Laser Altimeter (MLA) is one of the payload instruments on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, which was launched on August 3, 2004. MLA maps Mercury's shape and topographic landforms and other surface characteristics using a diode-pumped solid-state laser transmitter and a silicon avalanche photodiode receiver that measures the round-trip time of individual laser pulses. The laser transmitter has been operating nominally during planetary flyby measurements and in orbit about Mercury since March 2011. In this paper, we review the MLA laser transmitter telemetry data and evaluate the performance of solid-state lasers under extended operation in a space environment.

  6. Laser transmitter for space-based sodium lidar instrument

    NASA Astrophysics Data System (ADS)

    Yu, Anthony W.; Krainak, Michael A.; Janches, Diego; Konoplev, Oleg

    2016-05-01

    We are currently developing a laser transmitter to remotely measure Sodium (Na) by adapting existing lidar technology with space flight heritage. The developed instrumentation will serve as the core for the planning of a Heliophysics mission targeted to study the composition and dynamics of Earth's mesosphere based on a spaceborne lidar that will measure the mesospheric Na layer. We present performance results from our laser transmitter development effort with emphasis on wavelength tuning and power scaling of a diode-pumped Q-switched self-Raman c-cut Nd:YVO4 laser with intra-cavity frequency doubling that could produce multi-watt 589 nm wavelength output. We will review technologies that provide strong leverage for the sodium lidar laser system with strong heritage from past and current space flight missions.

  7. Airborne 2-Micron Double-Pulsed Integrated Path Differential Absorption Lidar for Column CO2 Measurement

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Remus, Ruben G.; Fay, James J.; Reithmaier, Karl

    2014-01-01

    Double-pulse 2-micron lasers have been demonstrated with energy as high as 600 millijouls and up to 10 Hz repetition rate. The two laser pulses are separated by 200 microseconds and can be tuned and locked separately. Applying double-pulse laser in DIAL system enhances the CO2 measurement capability by increasing the overlap of the sampled volume between the on-line and off-line. To avoid detection complicity, integrated path differential absorption (IPDA) lidar provides higher signal-to-noise ratio measurement compared to conventional range-resolved DIAL. Rather than weak atmospheric scattering returns, IPDA rely on the much stronger hard target returns that is best suited for airborne platforms. In addition, the IPDA technique measures the total integrated column content from the instrument to the hard target but with weighting that can be tuned by the transmitter. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO2 interaction studies or up to the free troposphere for optimum transport studies. Currently, NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micron IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

  8. Near-infrared transmittance pulse oximetry with laser diodes.

    PubMed

    Lopez Silva, Sonnia Maria; Dotor Castilla, Maria Luisa; Silveira Martin, Juan Pedro

    2003-07-01

    Pulse oximeters are widely used for noninvasive monitoring of oxygen saturation in arterial blood hemoglobin. We present a transmittance pulse oximetry system based on near-infrared (NIR) laser diodes (750 and 850 nm) for monitoring oxygen saturation of arterial blood hemoglobin. The pulse oximetry system is made up of the optical sensor, sensor electronics, and processing block. Also, we show experimental results obtained during the development of the whole NIR transmittance pulse oximetry system along with modifications in the sensor configuration, signal processing algorithm, and calibration procedure. Issues concerning wavelength selection and its implications for the improvement of the transmittance pulse oximetry technique are discussed. The results obtained demonstrate the proposed system's usefulness in monitoring a wide range of oxygen saturation levels.

  9. Implementation and validation of a CubeSat laser transmitter

    NASA Astrophysics Data System (ADS)

    Kingsbury, R. W.; Caplan, D. O.; Cahoy, K. L.

    2016-03-01

    The paper presents implementation and validation results for a CubeSat-scale laser transmitter. The master oscillator power amplifier (MOPA) design produces a 1550 nm, 200mW average power optical signal through the use of a directly modulated laser diode and a commercial fiber amplifier. The prototype design produces high-fidelity M-ary pulse position modulated (PPM) waveforms (M=8 to 128), targeting data rates > 10 Mbit/s while meeting a constraining 8W power allocation. We also present the implementation of an avalanche photodiode (APD) receiver with measured transmitter-to-receiver performance within 3 dB of theory. Via loopback, the compact receiver design can provide built-in self-test and calibration capabilities, and supports incremental on-orbit testing of the design.

  10. Designing Light Beam Transmittance Measuring Tool Using a Laser Pointer

    NASA Astrophysics Data System (ADS)

    Nuroso, H.; Kurniawan, W.; Marwoto, P.

    2016-08-01

    A simple instrument used for measuring light beam transmittance percentage made of window film has been developed. The instrument uses a laser pointer of 405 nm and 650 nm ±10% as a light source. Its accuracy approaches 80%. Transmittance data was found by comparing the light beam before and after passing the window film. The light intensity measuring unit was deleted by splitting the light source into two beams through a beam splitter. The light beam was changed into resistance by a NORP12 LDR sensor designed at a circuit of voltage divider rule of Khirchoff's laws. This conversion system will produce light beam intensity received by the sensor to become an equal voltage. This voltage will, then, be presented on the computer screen in the form of a real time graph via a 2.0 USB data transfer.

  11. Alexandrite laser transmitter development for airborne water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Chyba, Thomas H.; Ponsardin, Patrick; Higdon, Noah S.; DeYoung, Russell J.; Browell, Edward V.

    1995-01-01

    In the DIAL technique, the water vapor concentration profile is determined by analyzing the lidar backscatter signals for laser wavelengths tuned 'on' and 'off' a water vapor absorption line. Desired characteristics of the on-line transmitted laser beam include: pulse energy greater than or equal to 100 mJ, high-resolution tuning capability (uncertainty less than 0.25 pm), good spectral stability (jitter less than 0.5 pm about the mean), and high spectral purity (greater than 99 percent). The off-line laser is generally detuned less than 100 pm away from the water vapor line. Its spectral requirements are much less stringent. In our past research, we developed and demonstrated the airborne DIAL technique for water vapor measurements in the 720-nm spectral region using a system based on an alexandrite laser as the transmitter for the on-line wavelength and a Nd:YAG laser-pumped dye laser for the off-line wavelength. This off-line laser has been replaced by a second alexandrite laser. Diode lasers are used to injection seed both lasers for frequency and linewidth control. This eliminates the need for the two intracavity etalons utilized in our previous alexandrite laser and thereby greatly reduces the risk of optical damage. Consequently, the transmitted pulse energy can be substantially increased, resulting in greater measurement range, higher data density, and increased measurement precision. In this paper, we describe the diode injection seed source, the two alexandrite lasers, and the device used to line lock the on-line seed source to the water vapor absorption feature.

  12. Remote control radioactive-waste removal system uses modulated laser transmitter

    NASA Technical Reports Server (NTRS)

    Burcher, E. E.; Kopia, L. P.; Rowland, C. W.; Sinclair, A. R.

    1971-01-01

    Laser remote control system consists of transmitter, auto tracker, and receiver. Transmitter and tracker, packaged together and bore sighted, constitute control station, receiver is slave station. Model has five command channels and optical link operating range of 110 m.

  13. Prototype laser-diode-pumped solid state laser transmitters

    NASA Technical Reports Server (NTRS)

    Kane, Thomas J.; Cheng, Emily A. P.; Wallace, Richard W.

    1989-01-01

    Monolithic, diode-pumped Nd:YAG ring lasers can provide diffraction-limited, single-frequency, narrow-linewidth, tunable output which is adequate for use as a local oscillator in a coherent communication system. A laser was built which had a linewidth of about 2 kHz, a power of 5 milliwatts, and which was tunable over a range of 30 MHz in a few microseconds. This laser was phase-locked to a second, similar laser. This demonstrates that the powerful technique of heterodyne detection is possible with a diode-pumped laser used as the local oscillator. Laser diode pumping of monolithic Nd:YAG rings can lead to output powers of hundreds of milliwatts from a single laser. A laser was built with a single-mode output of 310 mW. Several lasers can be chained together to sum their power, while maintaining diffraction-limited, single frequency operation. This technique was demonstrated with two lasers, with a total output of 340 mW, and is expected to be practical for up to about ten lasers. Thus with lasers of 310 mW, output of up to 3 W is possible. The chaining technique, if properly engineered, results in redundancy. The technique of resonant external modulation and doubling is designed to efficiently convert the continuous wave, infrared output of our lasers into low duty-cycle pulsed green output. This technique was verified through both computer modeling and experimentation. Further work would be necessary to develop a deliverable system using this technique.

  14. Feasibility of a 30-meter space based laser transmitter

    NASA Technical Reports Server (NTRS)

    Berggren, R. R.; Lenertz, G. E.

    1975-01-01

    A study was made of the application of large expandable mirror structures in future space missions to establish the feasibility and define the potential of high power laser systems for such applications as propulsion and power transmission. Application of these concepts requires a 30-meter diameter, diffraction limited mirror for transmission of the laser energy. Three concepts for the transmitter are presented. These concepts include consideration of continuous as well as segmented mirror surfaces and the major stow-deployment categories of inflatable, variable geometry and assembled-in-space structures. The mirror surface for each concept would be actively monitored and controlled to maintain diffraction limited performance at 10.6 microns during operation. The proposed mirror configurations are based on existing aerospace state-of-the-art technology. The assembled-in-space concept appears to be the most feasible, at this time.

  15. Wind Profiling from a New Compact, Pulsed, 2-Micron, Coherent-Detection Doppler Lidar Transceiver during Wind Measurement Intercomparison

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Koch, Grady J.; Kavaya, Michael J.; Yu, Jirong; Beyon, Jeffrey Y.; Demoz, B.; Veneable, D.

    2009-01-01

    NASA Langley Research Center has a long history of developing 2-micron laser transmitter for wind sensing. With support from NASA Laser Risk Reduction Program (LRRP) and Instrument Incubator Program (IIP), NASA Langley Research Center has developed a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement. This lidar system was recently deployed at Howard University facility in Beltsville, Maryland, along with other wind lidar systems. Coherent Doppler wind lidar ground-based wind measurements and comparisons with other lidars and other sensors will be presented.

  16. Reflection Effects in Multimode Fiber Systems Utilizing Laser Transmitters

    NASA Technical Reports Server (NTRS)

    Bates, Harry E.

    1991-01-01

    A number of optical communication lines are now in use at NASA-Kennedy for the transmission of voice, computer data, and video signals. Now, all of these channels use a single carrier wavelength centered near 1300 or 1550 nm. Engineering tests in the past have given indications of the growth of systematic and random noise in the RF spectrum of a fiber network as the number of connector pairs is increased. This noise seems to occur when a laser transmitter is used instead of a LED. It has been suggested that the noise is caused by back reflections created at connector fiber interfaces. Experiments were performed to explore the effect of reflection on the transmitting laser under conditions of reflective feedback. This effort included computer integration of some of the instrumentation in the fiber optic lab using the Lab View software recently acquired by the lab group. The main goal was to interface the Anritsu Optical and RF spectrum analyzers to the MacIntosh II computer so that laser spectra and network RF spectra could be simultaneously and rapidly acquired in a form convenient for analysis. Both single and multimode fiber is installed at Kennedy. Since most are multimode, this effort concentrated on multimode systems.

  17. 2-Micron Triple-Pulse Integrated Path Differential Absorption Lidar Development for Simultaneous Airborne Column Measurements of Carbon Dioxide and Water Vapor in the Atmosphere

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong

    2016-01-01

    For more than 15 years, NASA Langley Research Center (LaRC) has contributed in developing several 2-micron carbon dioxide active remote sensors using the DIAL technique. Currently, an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development at NASA LaRC. This paper focuses on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of wavelength control, packaging and lidar integration. In addition, receiver development updates will also be presented, including telescope integration, detection systems and data acquisition electronics. Future plan for IPDA lidar system for ground integration, testing and flight validation will be presented.

  18. Qualification testing of the laser transmitter part for ESA's BepiColombo Laser Altimeter (BELA)

    NASA Astrophysics Data System (ADS)

    Weidlich, K.; Rech, M.; Kallenbach, R.

    2011-10-01

    The BepiColombo Laser Altimeter (BELA) is one of 11 instruments aboard ESA's Mercury Planetary Orbiter (MPO) scheduled for launch in 2014. BELA will record the surface profile of the planet while orbiting around it at a distance of 400km to 1500km1. The altimetry data constitute an important prerequisite for a number of remote sensing and observation techniques residing on the same orbiter. The BELA instrument comprises a laser transmitter and a receiver part, the design of the former is being presented and discussed in this paper. The laser transmitter encompasses a pair of diode-pumped, actively Q-switched Nd:YAG rod oscillators which have been miniaturized, light-weighted and dimensioned for high electrical to optical efficiency. The key performance parameters of the laser will be presented. Laser design trades which are relevant for a space mission to Mercury and the BELA instrument in particular are discussed. An overview is given to the laser qualification programme which includes performance and environmental tests. Test results are presented which have been recorded during the qualification test campaign currently in progress at Carl Zeiss Optronics.

  19. Multi-wavelength transmittance photoplethysmography with near infrared laser diodes during exercise

    NASA Astrophysics Data System (ADS)

    Lopez Silva, S. M.; Giannetti, R.; Dotor, M. L.; Golmayo, D.; Martin, P.; Miguel-Tobal, F.; Bilbao, A.; Silveira, J. P.

    2005-08-01

    The transmittance photoplethysmographic signals recorded with multiple NIR laser diodes in athletes along a maximal exercise test by treadmill ergometer and the results after processing are presented in comparison to the established reference techniques.

  20. 50 Mb/s, 220-mW Laser-Array Transmitter

    NASA Technical Reports Server (NTRS)

    Cornwell, Donald M., Jr.

    1992-01-01

    Laser transmitter based on injection locking produces single-wavelength, diffraction-limited, single-lobe beam. Output stage is array of laser diodes producing non-diffraction-limited, multi-mode beam in absence of injection locking. Suitable for both free-space and optical-fiber communication systems. Because beam from transmitter focused to spot as small as 5 micrometers, devices usable for reading and writing optical disks at increased information densities. Application also in remote sensing and ranging.

  1. Compact, High Energy 2-micron Coherent Doppler Wind Lidar Development for NASA's Future 3-D Winds Measurement from Space

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Koch, Grady; Yu, Jirong; Petros, Mulugeta; Beyon, Jeffrey; Kavaya, Michael J.; Trieu, Bo; Chen, Songsheng; Bai, Yingxin; Petzar, paul; Modlin, Edward A.; Barnes, Bruce W.; Demoz, Belay B.

    2010-01-01

    This paper presents an overview of 2-micron laser transmitter development at NASA Langley Research Center for coherent-detection lidar profiling of winds. The novel high-energy, 2-micron, Ho:Tm:LuLiF laser technology developed at NASA Langley was employed to study laser technology currently envisioned by NASA for future global coherent Doppler lidar winds measurement. The 250 mJ, 10 Hz laser was designed as an integral part of a compact lidar transceiver developed for future aircraft flight. Ground-based wind profiles made with this transceiver will be presented. NASA Langley is currently funded to build complete Doppler lidar systems using this transceiver for the DC-8 aircraft in autonomous operation. Recently, LaRC 2-micron coherent Doppler wind lidar system was selected to contribute to the NASA Science Mission Directorate (SMD) Earth Science Division (ESD) hurricane field experiment in 2010 titled Genesis and Rapid Intensification Processes (GRIP). The Doppler lidar system will measure vertical profiles of horizontal vector winds from the DC-8 aircraft using NASA Langley s existing 2-micron, pulsed, coherent detection, Doppler wind lidar system that is ready for DC-8 integration. The measurements will typically extend from the DC-8 to the earth s surface. They will be highly accurate in both wind magnitude and direction. Displays of the data will be provided in real time on the DC-8. The pulsed Doppler wind lidar of NASA Langley Research Center is much more powerful than past Doppler lidars. The operating range, accuracy, range resolution, and time resolution will be unprecedented. We expect the data to play a key role, combined with the other sensors, in improving understanding and predictive algorithms for hurricane strength and track. 1

  2. Fiber-Based Laser Transmitter for Oxygen A-Band Spectroscopy and Remote Sensing

    NASA Technical Reports Server (NTRS)

    Stephen, Mark A.; Abshire, James B.

    2010-01-01

    A fiber-based laser transmitter has been designed for active remote-sensing spectroscopy. The transmitter uses a master-oscillator-power-amplifier (MOPA) configuration with a distributed feedback diode-laser master oscillator and an erbium-doped fiber amplifier. The output from the MOPA is frequency-doubled with a periodically poled nonlinear crystal. The utility of this single-frequency, wavelength-tunable, power-scalable laser has been demonstrated in a spectroscopic measurement of the diatomic oxygen A-band.

  3. Single Frequency, Pulsed Laser Diode Transmitter for Dial Water Vapor Measurements at 935nm

    NASA Technical Reports Server (NTRS)

    Switzer, Gregg W.; Cornwell, Donald M., Jr.; Krainak, Michael A.; Abshire, James B.; Rall, Johnathan A. R.

    1998-01-01

    We report a tunable, single frequency, narrow linewidth, pulsed laser diode transmitter at 935.68nm for remote sensing of atmospheric water vapor. The transmitter consists of a CW, tunable, external cavity diode laser whose output is amplified 2OdB using a tapered diode amplifier. The output is pulsed for range resolved DIAL lidar by pulsing the drive current to the diode amplifier at 4kHz with a .5% duty cycle. The output from the transmitter is 36OnJ/pulse and is single spatial mode. It maintains a linewidth of less than 25MHz as its wavelength is tuned across the water vapor absorption line at 935.68nm. The transmitter design and its use in a water vapor measurement will be discussed.

  4. Noise-immune laser receiver - transmitters with the quantum sensitivity limit

    SciTech Connect

    Kutaev, Yu F; Mankevich, S K; Nosach, O Yu; Orlov, E P

    2009-11-30

    We consider the operation principles of noise-immune near-IR receiver - transmitters with the quantum sensitivity limit, in which active quantum filters based on iodine photodissociation quantum amplifiers and iodine lasers are used. The possible applications of these devices in laser location, laser space communication, for the search for signals from extraterrestrial civilisations and sending signals to extraterrestrial civilisations are discussed. (invited paper)

  5. Fiber-based, trace-gas, laser transmitter technology development for space

    NASA Astrophysics Data System (ADS)

    Stephen, Mark; Yu, Anthony; Chen, Jeffrey; Nicholson, Jeffrey; Engin, Doruk; Mathason, Brian; Wu, Stewart; Allan, Graham; Hasselbrack, William; Gonzales, Brayler; Han, Lawrence; Numata, Kenji; Storm, Mark; Abshire, James

    2015-09-01

    NASA's Goddard Space Flight Center (GSFC) is working on maturing the technology readiness of a laser transmitter designed for use in atmospheric CO2 remote-sensing. GSFC has been developing an airplane-based CO2 lidar instrument over several years to demonstrate the efficacy of the instrumentation and measurement technique and to link the science models to the instrument performance. The ultimate goal is to make space-based satellite measurements with global coverage. In order to accomplish this, we must demonstrate the technology readiness and performance of the components as well as demonstrate the required power-scaling to make the link with the required signal-to-noise-ratio (SNR). To date, all the instrument components have been shown to have the required performance with the exception of the laser transmitter. In this program we are working on a fiber-based master oscillator power amplifier (MOPA) laser transmitter architecture where we will develop a ruggedized package and perform the relevant environmental tests to demonstrate TRL-6. In this paper we will review our transmitter architecture and progress on the performance and packaging of the laser transmitter.

  6. Fiber-Based, Trace-Gas, Laser Transmitter Technology Development for Space

    NASA Technical Reports Server (NTRS)

    Stephen, Mark; Yu, Anthony; Chen, Jeffrey; Nicholson, Jeffrey; Engin, Doruk; Mathason, Brian; Wu, Stewart; Allan, Graham; Hasselbrack, William; Gonzalez, Brayler; Han, Lawrence; Numata, Kenji; Storm, Mark; Abshire, James

    2015-01-01

    NASA’s Goddard Space Flight Center (GSFC) is working on maturing the technology readiness of a laser transmitter designed for use in atmospheric CO2 remote-sensing. GSFC has been developing an airplane-based CO2 lidar instrument over several years to demonstrate the efficacy of the instrumentation and measurement technique and to link the science models to the instrument performance. The ultimate goal is to make space-based satellite measurements with global coverage. In order to accomplish this, we must demonstrate the technology readiness and performance of the components as well as demonstrate the required power-scaling to make the link with the required signal-to-noise-ratio (SNR). To date, all the instrument components have been shown to have the required performance with the exception of the laser transmitter.In this program we are working on a fiber-based master oscillator power amplifier (MOPA) laser transmitter architecture where we will develop a ruggedized package and perform the relevant environmental tests to demonstrate TRL-6. In this paper we will review our transmitter architecture and progress on the performance and packaging of the laser transmitter.

  7. High-power multi-beam diode laser transmitter for a flash imaging lidar

    NASA Astrophysics Data System (ADS)

    Holmlund, Christer; Aitta, Petteri; Kivi, Sini; Mitikka, Risto; Tyni, Lauri; Heikkinen, Veli

    2013-10-01

    VTT Technical Research Centre of Finland is developing the transmitter for the "Flash Optical Sensor for TErrain Relative NAVigation" (FOSTERNAV) multi-beam flash imaging lidar. FOSTERNAV is a concept demonstrator for new guidance, navigation and control (GNC) technologies to fulfil the requirements for landing and docking of spacecraft as well as for navigation of rovers. This paper presents the design, realisation and testing of the multi-beam continuous-wave (CW) laser transmitter to be used in a 256x256 pixel flash imaging lidar. Depending on the target distance, the lidar has three operation modes using either several beams with low divergence or one single beam with a large divergence. This paper describes the transmitter part of the flash imaging lidar with focus on the electronics and especially the laser diode drivers. The transmitter contains eight fibre coupled commercial diode laser modules with a total peak optical power of 32 W at 808 nm. The main requirement for the laser diode drivers was linear modulation up to a frequency of 20 MHz allowing, for example, low distortion chirps or pseudorandom binary sequences. The laser modules contain the laser diode, a monitoring photodiode, a thermo-electric cooler, and a thermistor. The modules, designed for non-modulated and low-frequency operation, set challenging demands on the design of the drivers. Measurement results are presented on frequency response, and eye diagrams for pseudo-random binary sequences.

  8. Long-duration Operation of 2-micron Coherent Doppler Lidar in Space

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Baker, Nathaniel R.; Baggot, Rene P.; Kavaya, Michael J.; Singh, Upendra N.

    2005-01-01

    The reliability and lifetime of laser remote sensing systems that can operate autonomously over a sufficiently long period are mainly constrained by the laser diode arrays (LDAs) used for pumping their laser transmitters. The lifetime of a 2-micron coherent lidar operating in space is particularly of concern in lieu of required pump pulse duration of Thulium and Holmium solid state lasers (approx. 1msec) that are considerably longer than those of more widely used 1-micron lasers (< 0.2 msec). A factor of 5 to 10 times longer pulse duration can easily translate to over an order of magnitude shorter lifetime for a typical commercially available high-power 2-D array. Therefore, it is imperative to address the lifetime and reliability of LDAs for pumping 2-micron lasers by exploring all the potential options that significantly prolong their life meeting the required operational lifetime of space-based coherent Doppler lidars. The leading causes of sudden failure and premature degradation of LDAs are intrinsic semiconductor defects, optical facet breakdown resulting from excessive localized heating, and thermo-mechanical stresses due to the extreme thermal cycling of the laser active regions1-2. Long pulse operation grossly amplifies the impact of these failure/degradation causes, particularly the thermo-mechanical stresses due to pulse-to-pulse thermal cycling. Therefore, several experimental setups have been developed to investigate each of the failure mechanisms and causes of premature degradation in order to evaluate various package designs, define the best operating parameters, and to guide the technology advancement, leading to highly reliable and very long lifetime LDAs5. Several areas of improvement in the packaging and fabrication process of laser diodes have already been identified and efforts towards implementing these improvements are well underway. These efforts include the use of advanced high thermal conductivity materials for packaging of laser diode

  9. Integration and test of high-speed transmitter electronics for free-space laser communications

    NASA Technical Reports Server (NTRS)

    Soni, Nitin J.; Lizanich, Paul J.

    1994-01-01

    The NASA Lewis Research Center in Cleveland, Ohio, has developed the electronics for a free-space, direct-detection laser communications system demonstration. Under the High-Speed Laser Integrated Terminal Electronics (Hi-LITE) Project, NASA Lewis has built a prototype full-duplex, dual-channel electronics transmitter and receiver operating at 325 megabit S per second (Mbps) per channel and using quaternary pulse-position modulation (QPPM). This paper describes the integration and testing of the transmitter portion for future application in free-space, direct-detection laser communications. A companion paper reviews the receiver portion of the prototype electronics. Minor modifications to the transmitter were made since the initial report on the entire system, and this paper addresses them. The digital electronics are implemented in gallium arsenide integrated circuits mounted on prototype boards. The fabrication and implementation issues related to these high-speed devices are discussed. The transmitter's test results are documented, and its functionality is verified by exercising all modes of operation. Various testing issues pertaining to high-speed circuits are addressed. A description of the transmitter electronics packaging concludes the paper.

  10. Remote sensing with a tunable alexandrite laser transmitter

    NASA Technical Reports Server (NTRS)

    Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Kagann, R. H.

    1985-01-01

    A high-resolution, tunable alexandrite laser system is described. Two alexandrite lasers are continuously tunable from 725-790 nm and have a bandwidth of 0.02/cm. The stability of the two lasers is evaluated. The line shape of the laser emission and spectral purity of the system were measured. The data reveal that the output consists of three axial modes with an overall width of 0.026/cm, and the spectral impurity of the alexandrite laser output is less than 0.01 percent. The ground-based lidar system is utilized for measuring atmospheric pressure profiles; the integrated absorption in the wings of lines in the O2 A band is studied to produce the profiles. An example of lidar-collected atmospheric pressure data is presented and compared with radiosonde data; only a 0.3 percent deviation between the data is observed.

  11. 2-micron Double Pulsed IPDA Lidar for Atmospheric CO2 Measurement

    NASA Astrophysics Data System (ADS)

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan; Murchison, Luke; Scola, Tory

    2015-04-01

    We have developed a high energy pulsed 2-micron IPDA lidar instrument to measure the atmospheric CO2 column density. The IPDA lidar is operated on the long wavelength wing of R(30) CO2 line at 2050.967 nm (4875.749 cm-1) in the side-line operation mode. The R(30) line is an excellent absorption line for the measurements of CO2 in 2µm wavelength region with regard to the strength of the absorption lines, low susceptibility to atmospheric temperature variability, and freedom from problematic interference with other absorption lines. The Ho:Tm:YLF laser transmitter is designed to be operated in a unique double pulse format that can produce two-pulse pair in 10 Hz operation. Typically, the output energies of the laser transmitter are 100mJ and 45mJ for the first pulse and the second pulse, respectively. We injection seed the first pulse with on-line frequency and the second pulse with off-line frequency. The IPDA lidar instrument size, weight and power consumption were restricted to small research aircraft payload requirements. The airborne IPDA lidar instrument measures the total integrated column content of CO2 from the instrument to the ground but with weighting that can be tuned by controlling the transmitted wavelengths. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO2 interaction studies or up to the free troposphere for optimum transport studies. The 2-μm CO2 IPDA lidar airborne demonstration was conducted during March 20, 2014 through April 10, 2014. IPDA lidar airborne flights included various operating and environmental conditions. Environmental conditions included different flight altitude up to 8.3 km, different ground target conditions such as vegetation, soil, ocean, snow and sand and different cloud conditions. Besides, some flights targeted power plant incinerators for investigating the IPDA sensitivity to CO2 plums. The lidar instrument is robust during all of the flights. This paper describes

  12. Robust Short-Pulse, High-Peak-Power Laser Transmitter for Optical Communications

    NASA Technical Reports Server (NTRS)

    Wright, Malcolm W.

    2009-01-01

    We report on a pulsed fiber based master oscillator power amplifier laser at 1550 nm to support moderate data rates with high peak powers in a compact package suitable for interplanetary optical communications. To accommodate pulse position modulation, the polarization maintaining laser transmitter generates pulses from 0.1 to 1 ns with variable duty cycle over a pulse repetition frequency range of 10 to 100 MHz.

  13. An overview of DREV's activities on pulsed CO2 laser transmitters: Frequency stability and lifetime aspects

    NASA Technical Reports Server (NTRS)

    Cruickshank, James; Pace, Paul; Mathieu, Pierre

    1987-01-01

    After introducing the desired features in a transmitter for laser radar applications, the output characteristics of several configurations of frequency-stable TEA-CO2 lasers are reviewed. Based on work carried out at the Defence Research Establishment Valcartier (DREV), output pulses are examined from short cavity lasers, CW-TEA hybrid lasers, and amplifiers for low power pulses. It is concluded that the technique of injecting a low-power laser beam into a TEA laser resonator with Gaussian reflectivity mirrors should be investigated because it appears well adapted to producing high energy, single mode, low chirp pulses. Finally, a brief report on tests carried out on catalysts composed of stannic oxide and noble metals demonstrates the potential of these catalysts, operating at close to room temperature, to provide complete closed-cycle laser operation.

  14. Terahertz inverse synthetic aperture radar (ISAR) imaging with a quantum cascade laser transmitter.

    PubMed

    Danylov, Andriy A; Goyette, Thomas M; Waldman, Jerry; Coulombe, Michael J; Gatesman, Andrew J; Giles, Robert H; Qian, Xifeng; Chandrayan, Neelima; Vangala, Shivashankar; Termkoa, Krongtip; Goodhue, William D; Nixon, William E

    2010-07-19

    A coherent transceiver using a THz quantum cascade (TQCL) laser as the transmitter and an optically pumped molecular laser as the local oscillator has been used, with a pair of Schottky diode mixers in the receiver and reference channels, to acquire high-resolution images of fully illuminated targets, including scale models and concealed objects. Phase stability of the received signal, sufficient to allow coherent image processing of the rotating target (in azimuth and elevation), was obtained by frequency-locking the TQCL to the free-running, highly stable optically pumped molecular laser. While the range to the target was limited by the available TQCL power (several hundred microwatts) and reasonably strong indoor atmospheric attenuation at 2.408 THz, the coherence length of the TQCL transmitter will allow coherent imaging over distances up to several hundred meters. Image data obtained with the system is presented.

  15. Optical Performance Measurements of the BELA EQM and FM Transmitter Laser during AIV

    NASA Astrophysics Data System (ADS)

    Althaus, C.; Michaelis, H.; Lingenauber, K.; Behnke, T.; Togno, S. d.; Kallenbach, R.; Wickhusen, K.; Althaus, C.

    2014-04-01

    The BepiColombo Laser Altimeter (BELA) onboard the Mercury Planetary Orbiter is Europe's first built Laser Altimeter for a planetary mission. Its main objectives are global mapping of Mercury's topography as well as measuring its tidal deformations to learn about the internal structure of this small terrestrial planet [1]. Crucial part of the instrument for this task is the transmitter laser. It must withstand all mission phases till operation in orbit and work within tight parameter margins. To ensure this a dedicated verification program has been performed at DLR Institute for Planetary Research Berlin which is described in the present paper.

  16. Simulation of fiber communication systems with semiconductor microcavity lasers as light transmitters

    NASA Astrophysics Data System (ADS)

    Zhao, Hongdong; Shen, Guangdi; Zhang, Cunshan; Lin, ShiMing; Cao, Jie; Wang, Shou-Wu

    1996-09-01

    We have simulated fiber communication systems with the semiconductor micro-cavity lasers as light transmitters using rate equations. When the spontaneous emission factor of micro-cavity equals 0.1 and the lasers are modulated by 10 Gbit/s numerical codes, we have obtained both the received eye diagram after they transmit 60 kilometers and the relations of the unit area of the eye diagram with the transmission distance. It will provide theoretical value for the application of the micro-cavity lasers in optical communication.

  17. Development of an Airborne Triple-Pulse 2-Micron Integrated Path Differential Absorption Lidar (IPDA) for Simultaneous Airborne Column Measurements of Carbon Dioxide and Water Vapor in the Atmosphere

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong; Antill, Charles W.; Remus, Ruben

    2016-01-01

    This presentation will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar being developed at NASA Langley Research Center with support from NASA ESTO Instrument Incubator Program. The development of this active optical remote sensing IPDA instrument is targeted for measuring both atmospheric carbon dioxide and water vapor in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plan for IPDA lidar system for ground integration, testing and flight validation will also be presented.

  18. Narrow linewidth UV laser transmitter for ozone DIAL remote sensing application

    NASA Astrophysics Data System (ADS)

    Chuang, Ti; Hansell, Joe; Shuman, Tim; Schum, Tom; Puffenberger, Kent; Burnham, Ralph

    2016-03-01

    Fibertek has demonstrated a dual-wavelength narrow linewidth UV laser transmitter for NASA airborne ozone DIAL remote sensing application. The application requires two narrow linewidth lasers in the UV region between 300 nm and 320 nm with at least 12 nm separation between the two wavelengths. Each UV laser was based on a novel ring structure incorporating an optical parametric oscillator (OPO) and a sum frequency generator (SFG). The fundamental pump source of the UV laser was a single frequency 532 nm laser, which was frequency-doubled from a diode-pumped, injection-seeded single frequency Nd:YAG laser operating at 1064 nm and 50 Hz repetition rate. The ring frequency converters generated UV wavelengths at 304 nm and 316 nm respectively. The demonstrated output energies were 2.6 mJ for 304 nm and 2.3 mJ for 316 nm UV lines, with room to potentially achieve more energy for each laser. Linewidth narrowing was achieved using a volume Bragg grating as the output coupler of the OPO in each ring oscillator. We obtained spectral linewidths (FWHM) of 0.12 nm for the 304 nm line and 0.1 nm for the 316 nm line, and the UV energy conversion efficiencies of 12.2% and 9.1%. Fibertek built an airborne DIAL transmitter based on the reported demonstration, which was a single optical module with dual-wavelength output at the demonstrated wavelengths. NASA plans to field the UV laser transmitter as a key component of the High Spectral Resolution Lidar-II (HSRL-II) high altitude airborne instrument to perform autonomous global ozone DIAL remote sensing field campaigns.

  19. A high performance laser diode transmitter for optical free space communication

    NASA Astrophysics Data System (ADS)

    Hildbebrand, U.; Ohm, G.; Wiesmann, Th.; Hildebrand, K.; Voit, E.

    1990-07-01

    For the ESA Semiconductor Intersatellite Link Experiment (SILEX), elements of the communication chain have been breadboarded. The electrooptical converter, called the laser diode transmitter package (LDTP), is described here. The requirements on the LDTP optical quality are deduced from the overall system requirements. The tolerable wavefront errors (WFE) and the stability of beam direction are most critical. Four breadboards have been assembled and tested. The very stringent requirements on WFE were surpassed, with a resulting rms value of 1/40 waves. In order to achieve this wavefront quality, the typical astigmatism of index-guided laser diodes (1-10 microns) had to be compensated by adjustable cylindrical lenses.

  20. Laser transmitter development for NASA's Global Ecosystem Dynamics Investigation (GEDI) lidar

    NASA Astrophysics Data System (ADS)

    Coyle, D. B.; Stysley, Paul R.; Poulios, Demetrios; Clarke, Greg B.; Kay, Richard B.

    2015-09-01

    The Global Ecosystems Dynamics Investigation (GEDI) Lidar, to be installed aboard the International Space Station in early 2018, will use 3 NASA laser transmitters to produce 14 parallel tracks of 25 m footprints on the Earth's surface. A global set of systematic canopy measurements will be derived, the most important of which are vegetation canopy top heights and the vertical distribution of canopy structure. Every digitized laser pulse waveform will provide 3-D biomass information for the duration of the mission. A total of 5 GEDI-HOMER lasers are to be built (1 ETU + 3 Flight + 1 spare) in-house at NASA-GSFC, and is based on a well-studied architecture, developed over several years in the Lasers and Electro-Optics Branch.

  1. 2-Micron Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurement

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan; Murchison, Luke

    2014-01-01

    A 2-micron high energy, pulsed Integrated Path Differential Absorption (IPDA) lidar has been developed for atmospheric CO2 measurements. Development of this lidar heavily leverages the 2-micron laser technologies developed in LaRC over the last decade. The high pulse energy, direct detection lidar operating at CO2 2-micron absorption band provides an alternate approach to measure CO2 concentrations. This new 2-micron pulsed IPDA lidar has been flown in spring of this year for total ten flights with 27 flight hours. It is able to make measurements of the total amount of atmospheric CO2 from the aircraft to the ground or cloud. It is expected to provide high-precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement.

  2. Low SWaP Semiconductor Laser Transmitter Modules For ASCENDS Mission Applications

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Rosiewicz, Alex; Coleman, Steven M.

    2012-01-01

    The National Research Council's (NRC) Decadal Survey (DS) of Earth Science and Applications from Space has identified the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) as an important atmospheric science mission. NASA Langley Research Center, working with its partners, is developing fiber laser architecture based intensity modulated CW laser absorption spectrometer for measuring XCO2 in the 1571 nm spectral band. In support of this measurement, remote sensing of O2 in the 1260 nm spectral band for surface pressure measurements is also being developed. In this paper, we will present recent progress made in the development of advanced transmitter modules for CO2 and O2 sensing. Advanced DFB seed laser modules incorporating low-noise variable laser bias current supply and low-noise variable temperature control circuit have been developed. The 1571 nm modules operate at >80 mW and could be tuned continuously over the wavelength range of 1569-1574nm at a rate of 2 pm/mV. Fine tuning was demonstrated by adjusting the laser drive at a rate of 0.7 pm/mV. Heterodyne linewidth measurements have been performed showing linewidth 200 kHz and frequency jitter 75 MHz. In the case of 1260 nm DFB laser modules, we have shown continuous tuning over a range of 1261.4 - 1262.6 nm by changing chip operating temperature and 1261.0 - 1262.0 nm by changing the laser diode drive level. In addition, we have created a new laser package configuration which has been shown to improve the TEC coefficient of performance by a factor of 5 and improved the overall efficiency of the laser module by a factor of 2.

  3. Multi-Wavelength, Multi-Beam, and Polarization-Sensitive Laser Transmitter for Surface Mapping

    NASA Technical Reports Server (NTRS)

    Yu, Anthony W.; Ramos-Izquierdo, Luis; Harding, David; Huss, Tim

    2011-01-01

    A multi-beam, multi-color, polarized laser transmitter has been developed for mapping applications. It uses commercial off-the-shelf components for a lowcost approach for a ruggedized laser suitable for field deployment. The laser transmitter design is capable of delivering dual wavelengths, multiple beams on each wavelength with equal (or variable) intensities per beam, and a welldefined state of polarization. This laser transmitter has been flown on several airborne campaigns for the Slope Imaging Multi-Polarization Photon Counting Lidar (SIMPL) instrument, and at the time of this reporting is at a technology readiness level of between 5 and 6. The laser is a 1,064-nm microchip high-repetition-rate laser emitting energy of about 8 microjoules per pulse. The beam was frequency-doubled to 532 nm using a KTP (KTiOPO4) nonlinear crystal [other nonlinear crystals such as LBO (LiB3O5) or periodically poled lithium niobiate can be used as well, depending on the conversion efficiency requirements], and the conversion efficiency was approximately 30 percent. The KTP was under temperature control using a thermoelectric cooler and a feedback monitoring thermistor. The dual-wavelength beams were then spectrally separated and each color went through its own optical path, which consisted of a beam-shaping lens, quarterwave plate (QWP), and a birefringent crystal (in this case, a calcite crystal, but others such as vanadate can be used). The QWP and calcite crystal set was used to convert the laser beams from a linearly polarized state to circularly polarized light, which when injected into a calcite crystal, will spatially separate the circularly polarized light into the two linear polarized components. The spatial separation of the two linearly polarized components is determined by the length of the crystal. A second set of QWP and calcite then further separated the two beams into four. Additional sets of QWP and calcite can be used to further split the beams into multiple

  4. The 1.2 micron CMOS technology

    NASA Technical Reports Server (NTRS)

    Pina, C. A.

    1985-01-01

    A set of test structures was designed using the Jet Propulsion Laboratory (JPL) test chip assembler and was used to evaluate the first CMOS-bulk foundry runs with feature sizes of 1.2 microns. In addition to the problems associated with the physical scaling of the structures, this geometry provided an additional set of problems, since the design files had to be generated in such a way as to be capable of being processed through p-well, n-well, and twin-well processing lines. This requirement meant that the files containing the geometric design rules as well as the structure design files had to produce process-insensitive designs, a requirement that does not apply to the more mature 3.0-micron CMOS feature size technology. Because of the photolithographic steps required with this feature size, the maximum allowable chip size was 10 x 10 mm, and this chip was divided into 24 project areas, with each area being 1.6 x 1.6 mm in size. The JPL-designed structures occupied 13 out of the 21 allowable project sizes and provided the only test information obtained from these three preliminary runs. The structures were used to successfully evaluate three different manufacturing runs through two separate foundries.

  5. Analysis and design of a high power laser adaptive phased array transmitter

    NASA Technical Reports Server (NTRS)

    Mevers, G. E.; Soohoo, J. F.; Winocur, J.; Massie, N. A.; Southwell, W. H.; Brandewie, R. A.; Hayes, C. L.

    1977-01-01

    The feasibility of delivering substantial quantities of optical power to a satellite in low earth orbit from a ground based high energy laser (HEL) coupled to an adaptive antenna was investigated. Diffraction effects, atmospheric transmission efficiency, adaptive compensation for atmospheric turbulence effects, including the servo bandwidth requirements for this correction, and the adaptive compensation for thermal blooming were examined. To evaluate possible HEL sources, atmospheric investigations were performed for the CO2, (C-12)(O-18)2 isotope, CO and DF wavelengths using output antenna locations of both sea level and mountain top. Results indicate that both excellent atmospheric and adaption efficiency can be obtained for mountain top operation with a micron isotope laser operating at 9.1 um, or a CO laser operating single line (P10) at about 5.0 (C-12)(O-18)2um, which was a close second in the evaluation. Four adaptive power transmitter system concepts were generated and evaluated, based on overall system efficiency, reliability, size and weight, advanced technology requirements and potential cost. A multiple source phased array was selected for detailed conceptual design. The system uses a unique adaption technique of phase locking independent laser oscillators which allows it to be both relatively inexpensive and most reliable with a predicted overall power transfer efficiency of 53%.

  6. development of a medium repetition rate (10 Hz - 500 Hz) diode pumped laser transmitter for airborne scanning altimetry

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry; Lindauer, Steven J., II; Kay, Richard B.

    1998-01-01

    Since the late 1980's, NASA has developed several small, all-solid state lasers of low repetition rates for use as transmitters in prototype LIDAR and raster scanned altimetry retrieval systems. Our early laser transmitters were developed for high resolution airborne altimetry which employed cavity dumping techniques to produce a pulse shape with a 1 ns rise time. The first such laser was the SUMR (Sub-millimeter resolution) transmitter which used a side pumped, D-shaped half-rod of Nd:YAG for the oscillator active media and produced approximately 3 ns pulses of 100 micro-J energy at a 40 Hz repetition rate. (Coyle and Blair, 1993; Coyle et al., 1995) After several upgrades to improve rep rate and pulse energy, the final version produced 1.2 mJ pulses at 120 Hz with a 3.7 ns pulse width. The laser has become known as SPLT (Sharp Pulsed Laser Transmitter), and has flown successfully on a variety of airborne altimetry missions. (Coyle and Blair, 1995; Blair et al., 1994) From building these systems, we have accrued valuable experience in delivering field-deployable lasers and have become aware of the advantages and disadvantages of employing new technologies. For example, even though the laser's main operating environment is in a "cold" aircraft during flight, the laser must still operate in very warm temperatures. This is important if the mission is based in the desert or a tropical climate since ground calibration data from stationary targets must be gathered before and after each data flight. Because conductive cooling is much more convenient than closed loop water flow, achieving the highest possible laser efficiency is becoming a high priority when designing a flight laser. This is especially true for lasers with higher pulse energies and repetition rates which are needed for high altitude scanning altimeters and LIDARs.

  7. Influence of beam wander on uplink of ground-to-satellite laser communication and optimization for transmitter beam radius.

    PubMed

    Guo, Hong; Luo, Bin; Ren, Yongxiong; Zhao, Sinan; Dang, Anhong

    2010-06-15

    We restudy the influence of beam wander on the uplink of ground-to-satellite laser communication, using the effective pointing error method, for a collimated untracked Gaussian beam under a weak atmospheric turbulence condition. It shows that the beam wander may cause significant increase in bit error rate (BER), and there exists an optimal transmitter radius for minimizing the value of BER. Further studies manifest that this optimal radius only changes with the laser wavelength and zenith angle, while independent on the satellite altitude and the fade threshold at the receiver. These results can be used in system design and optimization for the transmitter.

  8. Roles of the 2 microns gene products in stable maintenance of the 2 microns plasmid of Saccharomyces cerevisiae.

    PubMed Central

    Reynolds, A E; Murray, A W; Szostak, J W

    1987-01-01

    We have examined the replication and segregation of the Saccharomyces cerevisiae 2 microns circle. The amplification of the plasmid at low copy numbers requires site-specific recombination between the 2 microns inverted repeat sequences catalyzed by the plasmid-encoded FLP gene. No other 2 microns gene products are required. The overexpression of FLP in a strain carrying endogenous 2 microns leads to uncontrolled plasmid replication, longer cell cycles, and cell death. Two different assays show that the level of Flp activity decreases with increasing 2 microns copy number. This regulation requires the products of the REP1 and REP2 genes. These gene products also act together to ensure that 2 microns molecules are randomly segregated between mother and daughter cells at cell division. Images PMID:3316982

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  10. Transmitter and receiver antenna gain analysis for laser radar and communication systems

    NASA Technical Reports Server (NTRS)

    Klein, B. J.; Degnan, J. J.

    1973-01-01

    A comprehensive and fairly self-contained study of centrally obscured optical transmitting and receiving antennas is presented and is intended for use by the laser radar and communication systems designer. The material is presented in a format which allows the rapid and accurate evaluation of antenna gain. The Fresnel approximation to scalar wave theory is reviewed and the antenna analysis proceeds in terms of the power gain. Conventional range equations may then be used to calculate the power budget. The transmitter calculations, resulting in near and far field antenna gain patterns, assumes the antenna is illuminated by a laser operating in the fundamental cavity mode. A simple equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn which display the losses in antenna gain due to pointing errors and the cone angle of the outgoing beam as a function of antenna size and central obscuration. The use of telescope defocusing as an approach to spreading the beam for target acquisition is compared to some alternate methods.

  11. Electroabsorption-modulated widely tunable DBR laser transmitter for WDM-PONs.

    PubMed

    Han, Liangshun; Liang, Song; Wang, Huitao; Qiao, Lijun; Xu, Junjie; Zhao, Lingjuan; Zhu, Hongliang; Wang, Baojun; Wang, Wei

    2014-12-01

    We present an InP based distributed Bragg reflector (DBR) laser transmitter which has a wide wavelength tuning range and a high chip output power for wavelength division multiplexing passive optical network (WDM-PON) applications. By butt-jointing InGaAsP with 1.45 µm emission wavelength as the material of the grating section, the laser wavelength can be tuned for over 13 nm by the DBR current. Accompanied by varying the chip temperature, the tuning range can be further enlarged to 16 nm. With the help of the integrated semiconductor optical amplifier (SOA), the largest chip output power is over 30 mW. The electroabsorption modulator (EAM) is integrated into the device by the selective-area growth (SAG) technique. The 3 dB small signal modulation bandwidth of the EAM is over 13 GHz. The device has both a simple tuning scheme and a simple fabrication procedure, making it suitable for low cost massive production which is desirable for WDM-PON uses. PMID:25606965

  12. Loss of transmittance in fluoropolymer films due to laser-induced damage at 1053 and 351-nm

    SciTech Connect

    Whitman, P.; Milam, D.; Norton, M.; Sell, W.

    1997-12-01

    Thick fluoropolymer films are being evaluated as a potential `disposable` debris shield to protect high-peak-power laser optics from x-ray and target debris generated in inertial-confinement fusion-ignition experiments, Two obstacles to implementation are optical uniformity and damage threshold. To understand the damage characteristics, transmittance of single 1053- or 351-nm laser pulses has been measured for commercial fluoropolymer films in vacuum. Samples were tested at fluences up to 105 J/cm2 at 1053-nm and 13 J/cm2 at 351-nm. Both the total transmitted energy for a single shot and the temporal energy transmittance profile during the shot were measured as a function of fluence. In addition, the total focusable transmitted energy was recorded for 351 -nm pulses. Results show that transmittance decreases slowly during a single-pulse irradiation, allowing much of the energy to be transmitted at fluences which cause noticeable degradation to the film. The film transmits greater than 90% of the 351-nm energy delivered in a beam with spatial average fluence of 8 J/cm2 with modulation up to 15 J/cm2. For 1053-nm laser light, the films do not begin to exhibit noticeable transmittance loss until average fluences exceed 40 J/cm2.

  13. Miniature long-range light beam transmitter resorting to a high-power broad area laser diode

    NASA Astrophysics Data System (ADS)

    Yue, Wenjing; Lee, Sang-Shin

    2014-08-01

    A miniature long-range light beam transmitter, which taps into a high-power broad area laser diode (BALD), was realized to exhibit a uniform detectable width. An effective model was proposed to practically emulate the multimode characteristics of the beam generated by the BALD. The model, solely based on the emitting region and far-field divergence angle pertaining to the LD, is established through an incoherent superposition of multiple normalized Hermit-Gaussian modes. The feasibility of the proposed model was successfully verified in terms of the calculated and observed irradiance distributions of the light beams. A long-range light beam transmitter was then designed and constructed taking advantage of the BALD source in conjunction with a beam shaper. The manufactured transmitter was corroborated to provide an infrared beam with a constant detectable width of ~1 m, over a distance ranging up to 400 m, for a predefined threshold level.

  14. The 10 micrometer transmitter

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The design, fabrication tests, and engineering model components of a 10.6 mum wideband transceiver system are reported. The effort emphasized the transmitter subsystem, including the development of the laser, the modulator driver, and included productization of both the transmitter and local oscillator lasers. The transmitter subsystem is functionally compatible with the receiver engineering model terminal, and has undergone high data rate communication system testing against that terminal.

  15. Data Acquisition and Processing System for Airborne Wind Profiling with a Pulsed, 2-Micron, Coherent-Detection, Doppler Lidar System

    NASA Technical Reports Server (NTRS)

    Beyon, J. Y.; Koch, G. J.; Kavaya, M. J.

    2010-01-01

    A data acquisition and signal processing system is being developed for a 2-micron airborne wind profiling coherent Doppler lidar system. This lidar, called the Doppler Aerosol Wind Lidar (DAWN), is based on a Ho:Tm:LuLiF laser transmitter and 15-cm diameter telescope. It is being packaged for flights onboard the NASA DC-8, with the first flights in the summer of 2010 in support of the NASA Genesis and Rapid Intensification Processes (GRIP) campaign for the study of hurricanes. The data acquisition and processing system is housed in a compact PCI chassis and consists of four components such as a digitizer, a digital signal processing (DSP) module, a video controller, and a serial port controller. The data acquisition and processing software (DAPS) is also being developed to control the system including real-time data analysis and display. The system detects an external 10 Hz trigger pulse and initiates the data acquisition and processing process, and displays selected wind profile parameters such as Doppler shift, power distribution, wind directions and velocities. Doppler shift created by aircraft motion is measured by an inertial navigation/GPS sensor and fed to the signal processing system for real-time removal of aircraft effects from wind measurements. A general overview of the system and the DAPS as well as the coherent Doppler lidar system is presented in this paper.

  16. Far-Field Pattern Measurement of an Onboard Laser Transmitter by Use of a Space-to-Ground Optical Link.

    PubMed

    Toyoshima, M; Araki, K

    1998-04-01

    The far-field pattern of an onboard laser transmitter was measured with a transatmospheric optical link with a distance of ~33,000 km between the satellite and the optical ground station. The far-field pattern was acquired with a new method used to analyze statistically downlink irradiance data obtained at the ground station. The statistical tracking and pointing characteristics of the transmitter were taken into account in estimating downlink irradiance, assuming that there were no atmospheric scintillation effects. The peak directive gain of the downlink laser beam was 104.3 dB. The beam width (full width at half-maximum) was 28.5 x 17.5murad. These results were consistent with the results froma laboratory test undertaken before launch of the satellite.

  17. Progress of 2-micron Detectors for Application to Lidar Remote Sensing

    NASA Technical Reports Server (NTRS)

    Abedin, M. N.; Refaat, Tamer F.; Ismail, Syed; Koch, Grady; Singh, Upendra N.

    2008-01-01

    AlGaAsSb/InGaAsSb heterojunction phototransistors were developed at Astropower, Inc under Laser Risk Reduction Program (LRRP) for operation in the 2-micron region. These phototransistors were optimized for 2-micron detection and have high quantum efficiency (>60%), high gain (>10(exp 3)) and low noise-equivalent- power (<5x10(exp -14) W/Hz), while operating at low bias voltage. One of these phototransistors was tested in lidar mode using the 2-micron CO2 Differential Absorption Lidar (DIAL) system currently under development under the Instrument Incubator Program (IIP) at NASA Langley. Lidar measurements included detecting atmospheric structures consisting of thin clouds in the mid-altitude and near-field boundary layer. These test results are very promising for the application of phototransistors for the two-micron lidar remote sensing. In addition, HgCdTe avalanche photodiodes (APD) acquired from Raytheon were used in atmospheric testing at 2-microns. A discussion of these measurements is also presented in this paper.

  18. Fiber-Based Laser Transmitter at 1.57 Micrometers for Remote Sensing of Atmospheric Carbon Dioxide from Satellites

    NASA Technical Reports Server (NTRS)

    Yu, Anthony W.; Abshire, James B.; Stephen, Mark A.; Chen, Jeffrey R.; Wu, Stewart; Gonzalez, Brayler; Han, Lawrence; Numata, Kenji; Allan, Graham R.; Hasselbrack, William; Nicholson, Jeffrey W.; Yan, Man; Wisk, Patrick; DeSantolo, Anthony; DeSantolo, Anthony; Mangan, Brian; Puc, Gabe; Engin, Doruk; Mathason, Brian; Storm, Mark

    2015-01-01

    Over the past 20 years, NASA Goddard has successfully developed space-based lidar for remote sensing studies of the Earth and planets. The lidar in all missions to date have used diode pumped Nd:YAG laser transmitters. Recently we have been concentrating work on developing integrated path differential absorption (IPDA) lidar to measure greenhouse gases, with the goal of measurements from space. Due to the absorption spectrum of CO2 a fiber-based master oscillator power amplifier (MOPA) laser with a tunable seed source is an attractive laser choice. Fiber-based lasers offer a number of potential advantages for space, but since they are relatively new, challenges exist in developing them. In order to reduce risks for new missions using fiber-based lasers, we developed a 30- month plan to mature the technology of a candidate laser transmitter for space-based CO2 measurements to TRL-6. This work is also intended to reduce development time and costs and increase confidence in future mission success.

  19. Discovery of new 2 micron sources in Rho Ophiuchi

    NASA Technical Reports Server (NTRS)

    Barsony, M.; Carlstrom, J. E.; Burton, Michael G.; Russell, A. P. G.; Garden, R.

    1989-01-01

    A 144-sq-arcmin region of the Rho Oph star-forming cloud core was surveyed at 2.2 microns, complete to mK = 14. A total of 61 sources are detected, 26 of which have been previously reported, accounting for a total of 35 new sources with mK = 12-14. There is no turnover in the 2-micron luminosity function of the Rho Oph cloud core to a limiting sensitivity of mK = 14. Two of the newly discovered sources are binary companions to previously cataloged objects.

  20. Wavelength Locking to CO2 Absorption Line-Center for 2-Micron Pulsed IPDA Lidar Application

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Petros, Mulugeta; Antill, Charles W.; Singh, Upendra N.; Yu, Jirong

    2016-01-01

    An airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is currently under development at NASA Langley Research Center (LaRC). This IPDA lidar system targets both atmospheric carbon dioxide (CO2) and water vapor (H2O) column measurements. Independent wavelength control of each of the transmitted laser pulses is a key feature for the success of this instrument. The wavelength control unit provides switching, tuning and locking for each pulse in reference to a 2-micron CW (Continuous Wave) laser source locked to CO2 line-center. Targeting the CO2 R30 line center, at 2050.967 nanometers, a wavelength locking unit has been integrated using semiconductor laser diode. The CO2 center-line locking unit includes a laser diode current driver, temperature controller, center-line locking controller and CO2 absorption cell. This paper presents the CO2 center-line locking unit architecture, characterization procedure and results. Assessment of wavelength jitter on the IPDA measurement error will also be addressed by comparison to the system design.

  1. Laser transmitter design and performance for the slope imaging multi-polarization photon-counting lidar (SIMPL) instrument

    NASA Astrophysics Data System (ADS)

    Yu, Anthony W.; Harding, David J.; Dabney, Philip W.

    2016-03-01

    The Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) is a polarimetric, two-color, multi-beam push broom laser altimeter developed through the NASA Earth Science Technology Office Instrument Incubator Program. It has flown successfully on multiple airborne platforms beginning in 2008.1 It was developed to demonstrate new altimetry capabilities that combine height measurements and information about surface composition and properties. In this talk we will discuss the laser transmitter design and performance and present recent science data collected over the Greenland ice sheet and arctic sea ice in support of the second NASA Ice Cloud and land Elevation Satellite (ICESat-2) mission to be launched in 2017.2

  2. Wavelength-switchable fiber laser based on temperature-dependent transmittance of a LPFG

    NASA Astrophysics Data System (ADS)

    Anzueto-Sánchez, G.; Castrellon-Uribe, J.; Torres-Gómez, I.; Martínez-Rios, A.; Osuna-Galán, I.

    2011-09-01

    A wavelength-switchable erbium-doped fiber ring laser is demonstrated and reported. The erbium-doped fiber net gain of the fiber laser is modified by controlled heating of a Long Period Fiber Grating (LPFG) inserted into the laser cavity. The rejection band of the LPFG is altered in the resonant wavelength and loss according to the exposed temperature and consequently, the operating wavelength of the fiber laser can be switched from a single wavelength operation at 1563 nm to a simultaneous operation at 1527 and 1563 nm. The laser system can be used as a temperature fiber sensor as well.

  3. 2.5 MHz Line-Width High-energy, 2 Micrometer Coherent Wind Lidar Transmitter

    NASA Technical Reports Server (NTRS)

    Petros, Mulugeta; Yu, Jirong; Trieu, Bo; Bai, Yingxin; Petzar, Paul; Singh, Upendra N.; Reithmaier, Karl

    2007-01-01

    2 micron solid-state lasers are the primary choice for coherent Doppler wind detection. As wind lidars, they are used for wake vortex and clear air turbulence detection providing air transport safety. In addition, 2 micron lasers are one of the candidates for CO2 detection lidars. The rich CO2 absorption line around 2 micron, combined with the long upper state life of time, has made Ho based 2 micron lasers a viable candidate for CO2 sensing DIAL instrument. The design and fabrication of a compact coherent laser radar transmitter for Troposphere wind sensing is under way. This system is hardened for ground as well as airborne applications. As a transmitter for a coherent wind lidar, this laser has stringent spectral line width and beam quality requirements. Although the absolute wavelength does not have to be fixed for wind detection, to maximize return signal, the output wavelength should avoid atmospheric CO2 and H2O absorption lines. The base line laser material is Ho:Tm:LuLF which is an isomorph of Ho:Tm:YLF. LuLF produces 20% more output power than Ho:Tm:YLF. In these materials the Tm absorption cross-section, the Ho emission cross-section, the Tm to Ho energy transfer parameters and the Ho (sup 5) I (sub 7) radiative life time are all identical. However, the improved performance of the LuLF is attributed to the lower thermal population in the (sup 5) I (sub 8) manifold. It also provides higher normal mode to Q-switch conversion than YLF at high pump energy indicating a lower up-conversion. The laser architecture is composed of a seed laser, a ring oscillator, and a double pass amplifier. The seed laser is a single longitudinal mode with a line width of 13 KHz. The 100mJ class oscillator is stretched to 3 meters to accommodate the line-width requirement without compromising the range resolution of the instrument. The amplifier is double passed to produce greater than 300mJ energy.

  4. Laser Atmospheric Transmitter Receiver-Network (LAnTeRN): A new approach for active measurement of atmospheric greenhouse gases

    NASA Astrophysics Data System (ADS)

    Dobler, J. T.; Braun, M.; Zaccheo, T.

    2012-12-01

    The Laser Atmospheric Transmitter Receiver-Network (LAnTeRN) is a new measurement concept that will enable local, regional and continental determination of key greenhouse gases, with unparalleled accuracy and precision. This new approach will offer the ability to make low bias, high precision, quasi-continuous, measurements to the accuracies required for separating anthropogenic and biogenic sources and sinks. In 2004 ITT Exelis developed an airborne demonstration unit, based on an intensity modulated continuous wave (IM-CW) lidar approach, for actively measuring atmospheric CO2 and O2. The multi-functional fiber laser lidar (MFLL) system relies on low peak power, high reliability, and efficient telecom laser components to implement this unique measurement approach. While evaluating methods for discriminating against thin clouds for the MFLL instrument, a new measurement concept was conceived. LAnTeRN has several fundamental characteristics in common with the MFLL instrument, but is a fundamentally different implementation and capability. The key difference is that LAnTeRN operates in transmission rather than in the traditional backscatter lidar configuration, which has several distinct advantages. Operating as a forward scatter, bistatic lidar system, LAnTeRN enables consideration of continuous monitoring from a geostationary orbit to multiple locations on the ground. Having the receivers on the ground significantly lowers cost and risk compared to an all space based mission, and allows the transmitter subsystem to be implemented, near term, as a hosted payload. Furthermore, the LAnTeRN measurement approach is also applicable for ground to ground measurements where high precision measurements over a long open path is required, such as facilities monitoring, or monitoring of passive volcanoes and fault lines. Using narrow linewidth laser sources allows flexibility to select the position on the absorption feature being probed. This feature allows for weighting the

  5. All-fiber laser transmitter, operating in the eye-safe spectral region: first stage

    NASA Astrophysics Data System (ADS)

    Michalska, Maria; Swiderski, Jacek; Zendzian, Waldemar

    2013-01-01

    The paper presents a current state of the project aiming to develop a compact and mobile pulsed laser source, operated in "eye-safe" spectral region (1.5 μm). It will be a high power, all-fiber system generating nanosecond pulses with repetition rate ranging from tens to hundreds kHz and built in Master Oscillator Power Amplifier (MOPA) configuration. First amplifying cascade of the system has been developed. Distributed Feedback (DFB) laser diode with home-built supply and pulse control system was used as a master oscillator. It can generate rectangular laser pulses with independently changeable repetition rate (10 - 200 kHz) and pulse width (20 - 300 ns). The system provides over 34 dB optical gain. In addition, simulations of amplification laser radiation in the active fiber for different input pulse energies in relation to saturation energy were presented. Furthermore theoretical and experimental optimization of an active fiber length was done. In the first elaborated stage of amplifier 18,1 % slope efficiency was obtained.

  6. High Energy, Single-Mode, All-Solid-State and Tunable UV Laser Transmitter

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Singh, Upendra N.; Hovis, FLoyd

    2007-01-01

    A high energy, single mode, all solid-state Nd:YAG laser primarily for pumping an UV converter is developed. Greater than 1 J/pulse at 50 HZ PRF and pulse widths around 22 ns have been demonstrated. Higher energy, greater efficiency may be possible. Refinements are known and practical to implement. Technology Demonstration of a highly efficient, high-pulse-energy, single mode UV wavelength generation using flash lamp pumped laser has been achieved. Greater than 90% pump depletion is observed. 190 mJ extra-cavity SFG; IR to UV efficiency > 21% (> 27% for 1 mJ seed). 160 mJ intra-cavity SFG; IR to UV efficiency up to 24% Fluence < 1 J/sq cm for most beams. The pump beam quality of the Nd:YAG pump laser is being refined to match or exceed the above UV converter results. Currently the Nd:YAG pump laser development is a technology demonstration. System can be engineered for compact packaging.

  7. Photometric variability of Charon at 2.2 microns

    NASA Technical Reports Server (NTRS)

    Bosh, A. S.; Young, L. A.; Elliot, J. L.; Hammel, H. B.; Baron, R. L.

    1992-01-01

    Pluto-Charon images obtained on each of four nights at 2.2, 1.2, and 1.7 microns are presently fitted by a two-source image model in which the position of Charon and the ratio of its signal to that of Pluto are free parameters. At 2.2 microns, Charon is fainter than Pluto by magnitudes which, when combined with Pluto-Charon system photometry, yield apparent magnitudes of 15.01 + or - 0.08 for Charon at 0.06 lightcurve phase and 15.46 + or - 0.05 at lightcurve phase 0.42. In view of these results, Charon is variable in this filter bypass due to geometric albedo changes as a function of longitude.

  8. Mars Atmospheric Characterization Using Advanced 2-Micron Orbiting Lidar

    NASA Technical Reports Server (NTRS)

    Singh, U.; Engelund, W.; Refaat, T.; Kavaya, M.; Yu, J.; Petros, M.

    2015-01-01

    Mars atmospheric characterization is critical for exploring the planet. Future Mars missions require landing massive payloads to the surface with high accuracy. The accuracy of entry, descent and landing (EDL) of a payload is a major technical challenge for future Mars missions. Mars EDL depends on atmospheric conditions such as density, wind and dust as well as surface topography. A Mars orbiting 2-micron lidar system is presented in this paper. This advanced lidar is capable of measuring atmospheric pressure and temperature profiles using the most abundant atmospheric carbon dioxide (CO2) on Mars. In addition Martian winds and surface altimetry can be mapped, independent of background radiation or geographical location. This orbiting lidar is a valuable tool for developing EDL models for future Mars missions.

  9. Infrared spectrum of Io, 2.8-5.2 microns

    NASA Astrophysics Data System (ADS)

    Cruikshank, D. P.

    1980-02-01

    The reflectance spectrum of Io is presented from 2.8 to 5.2 microns demonstrating the full extent of the broad and deep spectral absorption between 3.5 and 4.8 microns. Laboratory spectra of nitrates and carbonates diluted with sulfur do not satisfactorily reproduce the Io spectrum, but new information based on recently discovered volcanic activity on the satellite lead to consideration of other classes of compounds reported by Fanale et al. (1979). It is concluded that the variability of the supply of condensible SO2 gas to the surface of Io, its removal by sublimination, and the temporal variations in the strength of the SO2 band may provide an index of volcanic activity on Io that can be monitored from the earth.

  10. Design and Performance of the Vegetation Canopy Lidar (VCL) Laser Transmitter

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry; Kay, Richard B.; Lindauer, Steven J., II

    2002-01-01

    The Vegetation Canopy Lidar (VCL) laser is a Nd:YAG Q-switched, diode side-pumped, zig-zag slab design producing 10 ns, 15 mJ pulses at 1064 nm. It employs an unstable resonator as well as a graded reflectivity output coupler with a Gaussian reflectivity profile. In order to conserve power, a conductively cooled design is employed and is designed to operate over a range of 25 C without active thermal control. The laser is an oscillator-only design and equipped with an 15X beam expander to limit the output divergence to less than 60 microrad. Thermal lensing compensation in the side-pumped slab was performed with different treatments of the x and y portions of the z-directed beam. Performance data as a function of temperature are given.

  11. Side-line tunable laser transmitter for differential absorption lidar measurements of CO2: design and application to atmospheric measurements

    NASA Astrophysics Data System (ADS)

    Koch, Grady J.; Beyon, Jeffrey Y.; Gibert, Fabien; Barnes, Bruce W.; Ismail, Syed; Petros, Mulugeta; Petzar, Paul J.; Yu, Jirong; Modlin, Edward A.; Davis, Kenneth J.; Singh, Upendra N.

    2008-03-01

    A 2 μm wavelength, 90 mJ, 5 Hz pulsed Ho laser is described with wavelength control to precisely tune and lock the wavelength at a desired offset up to 2.9 GHz from the center of a CO2 absorption line. Once detuned from the line center the laser wavelength is actively locked to keep the wavelength within 1.9 MHz standard deviation about the setpoint. This wavelength control allows optimization of the optical depth for a differential absorption lidar (DIAL) measuring atmospheric CO2 concentrations. The laser transmitter has been coupled with a coherent heterodyne receiver for measurements of CO2 concentration using aerosol backscatter; wind and aerosols are also measured with the same lidar and provide useful additional information on atmospheric structure. Range-resolved CO2 measurements were made with <2.4% standard deviation using 500 m range bins and 6.7 min⁡ (1000 pulse pairs) integration time. Measurement of a horizontal column showed a precision of the CO2 concentration to <0.7% standard deviation using a 30 min⁡ (4500 pulse pairs) integration time, and comparison with a collocated in situ sensor showed the DIAL to measure the same trend of a diurnal variation and to detect shorter time scale CO2 perturbations. For vertical column measurements the lidar was setup at the WLEF tall tower site in Wisconsin to provide meteorological profiles and to compare the DIAL measurements with the in situ sensors distributed on the tower up to 396 m height. Assuming the DIAL column measurement extending from 153 m altitude to 1353 m altitude should agree with the tower in situ sensor at 396 m altitude, there was a 7.9 ppm rms difference between the DIAL and the in situ sensor using a 30 min⁡ rolling average on the DIAL measurement.

  12. The 2-micron plasmid as a nonselectable, stable, high copy number yeast vector

    NASA Technical Reports Server (NTRS)

    Ludwig, D. L.; Bruschi, C. V.

    1991-01-01

    The endogenous 2-microns plasmid of Saccharomyces cerevisiae has been used extensively for the construction of yeast cloning and expression plasmids because it is a native yeast plasmid that is able to be maintained stably in cells at high copy number. Almost invariably, these plasmid constructs, containing some or all 2-microns sequences, exhibit copy number levels lower than 2-microns and are maintained stably only under selective conditions. We were interested in determining if there was a means by which 2-microns could be utilized for vector construction, without forfeiting either copy number or nonselective stability. We identified sites in the 2-microns plasmid that could be used for the insertion of genetic sequences without disrupting 2-microns coding elements and then assessed subsequent plasmid constructs for stability and copy number in vivo. We demonstrate the utility of a previously described 2-microns recombination chimera, pBH-2L, for the manipulation and transformation of 2-microns as a pure yeast plasmid vector. We show that the HpaI site near the STB element in the 2-microns plasmid can be utilized to clone yeast DNA of at least 3.9 kb with no loss of plasmid stability. Additionally, the copy number of these constructs is as high as levels reported for the endogenous 2-microns.

  13. Characterization of a High-SpeedHigh-Power Semiconductor Master-Oscillator Power-Amplifier (MOPA) Laser as a Free-Space Transmitter

    NASA Astrophysics Data System (ADS)

    Wright, M. W.

    2000-04-01

    Semiconductor lasers offer promise as high-speed transmitters for free-space optical communication systems. This article examines the performance of a semiconductor laser system in a master-oscillator power-amplifier (MOPA) geometry developed through a Small Business Innovation Research (SBIR) contract with SDL, Inc. The compact thermo-electric cooler (TEC) packaged device is capable of 1-W output optical power at greater than 2-Gb/s data rates and a wavelength of 960 nm. In particular, we have investigated the effects of amplified spontaneous emission on the modulation extinction ratio and bit-error rate (BER) performance. BERs of up to 10^(-9) were possible at 1.4 Gb/s; however, the modulation extinction ratio was limited to 6 dB. Other key parameters for a free-space optical transmitter, such as the electrical-optical efficiency (24 percent) and beam quality, also were measured.

  14. Silicon photonics WDM transmitter with single section semiconductor mode-locked laser

    NASA Astrophysics Data System (ADS)

    Müller, Juliana; Hauck, Johannes; Shen, Bin; Romero-García, Sebastian; Islamova, Elmira; Azadeh, Saeed Sharif; Joshi, Siddharth; Chimot, Nicolas; Moscoso-Mártir, Alvaro; Merget, Florian; Lelarge, François; Witzens, Jeremy

    2015-04-01

    We demonstrate a wavelength domain-multiplexed (WDM) optical link relying on a single section semiconductor mode-locked laser (SS-MLL) with quantum dash (Q-Dash) gain material to generate 25 optical carriers spaced by 60.8 GHz, as well as silicon photonics (SiP) resonant ring modulators (RRMs) to modulate individual optical channels. The link requires optical reamplification provided by an erbium-doped fiber amplifier (EDFA) in the system experiments reported here. Open eye diagrams with signal quality factors (Q-factors) above 7 are measured with a commercial receiver (Rx). For higher compactness and cost effectiveness, reamplification of the modulated channels with a semiconductor optical amplifier (SOA) operated in the linear regime is highly desirable. System and device characterization indicate compatibility with the latter. While we expect channel counts to be primarily limited by the saturation output power level of the SOA, we estimate a single SOA to support more than eight channels. Prior to describing the system experiments, component design and detailed characterization results are reported including design and characterization of RRMs, ring-based resonant optical add-drop multiplexers (RR-OADMs) and thermal tuners, S-parameters resulting from the interoperation of RRMs and RR-OADMs, and characterization of Q-Dash SS-MLLs reamplified with a commercial SOA. Particular emphasis is placed on peaking effects in the transfer functions of RRMs and RR-OADMs resulting from transient effects in the optical domain, as well as on the characterization of SS-MLLs in regard to relative intensity noise (RIN), stability of the modes of operation, and excess noise after reamplification.

  15. Wind Measurements with High Energy 2 Micron Coherent Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Barnes, Bruce W.; Koch, Grady J.; Petros, Mulugeta; Beyon, Jeffrey Y.; Amzajerdian, Farzin; Yu, Ji-Rong; Kavaya, Michael J.; Singh, Upendra N.

    2004-01-01

    A coherent Doppler lidar based on an injection seeded Ho:Tm:YLF pulsed laser was developed for wind measurements. A transmitted pulse energy over 75 mJ at 5 Hz repetition rate has been demonstrated. Designs are presented on the laser, injection seeding, receiver, and signal processing subsystems. Sample data of atmospheric measurements are presented including a wind profile extending from the atmospheric boundary layer (ABL) to the free troposphere.

  16. A wavelength tunable ONU transmitter based on multi-mode Fabry-Perot laser and micro-ring resonator for bandwidth symmetric TWDM-PON

    NASA Astrophysics Data System (ADS)

    Gao, Zhensen; Sun, Xiao; Zhang, Kaibin

    2016-02-01

    Wavelength tunable optical transmitter is an essential component for the newly standardized time and wavelength division multiplexed passive optical network (TWDM-PON), where tunable ONU with 10Gb/s bit rate is desired to provide 40Gb/s symmetric bandwidth. In this paper, a novel wavelength tunable optical transmitter is proposed by reusing legacy low speed multi-mode Fabry-Perot laser and connecting it with an integrated photonic chip with two coupled micro-ring resonators to generate a tunable single mode signal based on Vernier effect for 10Gb/s high speed modulation, which makes it as a promising solution for colorless ONU in future symmetric TWDM-PON.

  17. Characterization of the Q-switched MOBLAS Laser Transmitter and Its Ranging Performance Relative to a PTM Q-switched System

    NASA Technical Reports Server (NTRS)

    Degnan, J. J., III; Zagwodski, T. W.

    1979-01-01

    A prototype Q-switched Nd:YAG laser transmitter intended for use in the NASA mobile laser ranging system was subjected to various tests of temporal pulse shape and stability, output energy and stability, beam divergence, and range bias errors. Peak to peak variations in the mean range were as large as 30 cm and drift rates of system bias with time as large as 6 mm per minute of operation were observed. The incorporation of a fast electro-optic cavity dump into the oscillator gave significantly improved results. Reevaluation of the ranging performance after modification showed a reduction in the peak to peak variation in the mean range to the 2 or 3 cm level and a drift rate of system time biases of less than 1 mm per minute of operation. A qualitative physical explanation for the superior performance of cavity dumped lasers is given.

  18. UWB transmitter

    DOEpatents

    Dallum, Gregory E.; Pratt, Garth C.; Haugen, Peter C.; Romero, Carlos E.

    2013-01-15

    An ultra-wideband (UWB) dual impulse transmitter is made up of a trigger edge selection circuit actuated by a single trigger input pulse; a first step recovery diode (SRD) based pulser connected to the trigger edge selection circuit to generate a first impulse output; and a second step recovery diode (SRD) based pulser connected to the trigger edge selection circuit in parallel to the first pulser to generate a second impulse output having a selected delay from the first impulse output.

  19. Influence of outgassing organic contamination on the transmittance and laser-induced damage of SiO2 sol-gel antireflection film

    NASA Astrophysics Data System (ADS)

    Yang, Liang; Xiang, Xia; Miao, Xinxiang; Li, Zhijie; Zhou, Guorui.; Yan, Zhonghua; Yuan, Xiaodong; Zheng, Wanguo; Zu, Xiaotao

    2015-12-01

    The influence of organic contamination (rubber outgassing) on the transmittance of the SiO2 sol-gel antireflection (AR) film and laser-induced damage threshold (LIDT) at 355 nm for 3ω AR film and at 1064 nm for 1ω AR film is studied. The correlation between the contamination time and the transmittance loss/LIDT of 1ω/3ω AR film is also investigated both in atmospheric and vacuum environments. The results show that the transmittance loss increases with increasing contamination time, and the LIDT decreases with increasing contamination time for both in atmospheric and vacuum environments. In addition, the resistance against contamination of the 1ω film is stronger than 3ω film, and the contamination is more serious in vacuum than in an atmosphere environment for the same contamination time. Meanwhile, the damage mechanism is also discussed. It indicated that both the porous structure and photo-thermal absorption contribute to the decreasing LIDT of the sol-gel AR film.

  20. Compact, Engineered, 2-Micron Coherent Doppler Wind Lidar Prototype: A New NASA Instrument Incubator Program Project

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Koch, Grady J.; Yu, Jirong; Singh, Upendra N.; Amzajerdian, Farzin; Wang, Jinxue; Petros, Mulugeta

    2005-01-01

    A new project, selected in 2005 by NASA s Science Mission Directorate (SMD) under the Instrument Incubator Program (IIP), will be described. The 3-year effort is intended to design, fabricate, and demonstrate a packaged, rugged, compact, space-qualifiable coherent Doppler wind lidar (DWL) transceiver capable of future validation in an aircraft and/or Unmanned Aerial Vehicle (UAV). The packaged DWL will utilize the numerous advances in pulsed, solid-state, 2-micron laser technology at NASA s Langley Research Center (LaRC) in such areas as crystal composition, architecture, efficiency, cooling techniques, pulse energy, and beam quality. The extensive experience of Raytheon Space and Airborne Systems (RSAS) in coherent lidar systems, in spacebased sensors, and in packaging rugged lidar systems will be applied to this project. The packaged transceiver will be as close to an envisioned space-based DWL system as the resources and technology readiness allow. We will attempt to facilitate a future upgrade to a coherent lidar system capable of simultaneous wind and CO2 concentration profile measurements. Since aerosol and dust concentration is also available from the lidar signal, the potential for a triple measurement lidar system is attractive for both Earth and Mars remote sensing. A key follow on step after the IIP will be to add a telescope, scanner, and software for aircraft validation. This IIP should also put us in a position to begin a parallel formulation study in the 2006-2007 timeframe for a space-based DWL demonstration mission early next decade.

  1. Solid-state 3D imaging using a 1nJ/100ps laser diode transmitter and a single photon receiver matrix.

    PubMed

    Jahromi, Sahba; Jansson, Jussi-Pekka; Kostamovaara, Juha

    2016-09-19

    A 3D imaging concept based on pulsed time-of-flight focal plane imaging is presented which can be tailored flexibly in terms of performance parameters such as range, image update rate, field-of-view, 2D resolution, depth accuracy, etc. according to the needs of different applications. The transmitter is based on a laser diode operating in enhanced gain-switching mode with a simple MOS/CMOS-switch current driver and capable of producing short (~100ps FWHM) high energy (up to nJ) pulses at a high pulsing rate. The receiver consists of 2D SPAD and TDC arrays placed on the same die, but in separate arrays. Paraxial optics can be used to illuminate the target field-of-view with the receiver placed at the focal plane of the receiver lens. To validate the concept, a prototype system is presented with a bulk laser diode/MOS driver operating at a wavelength of 870nm with a pulsing rate of 100kHz as the transmitter and a single-chip 9x9 SPAD array with 10-channel TDC as the receiver. The possibility of using this method as a solid-state solution to the task of 3D imaging is discussed in the light of the results derived from this prototype.

  2. Solid-state 3D imaging using a 1nJ/100ps laser diode transmitter and a single photon receiver matrix.

    PubMed

    Jahromi, Sahba; Jansson, Jussi-Pekka; Kostamovaara, Juha

    2016-09-19

    A 3D imaging concept based on pulsed time-of-flight focal plane imaging is presented which can be tailored flexibly in terms of performance parameters such as range, image update rate, field-of-view, 2D resolution, depth accuracy, etc. according to the needs of different applications. The transmitter is based on a laser diode operating in enhanced gain-switching mode with a simple MOS/CMOS-switch current driver and capable of producing short (~100ps FWHM) high energy (up to nJ) pulses at a high pulsing rate. The receiver consists of 2D SPAD and TDC arrays placed on the same die, but in separate arrays. Paraxial optics can be used to illuminate the target field-of-view with the receiver placed at the focal plane of the receiver lens. To validate the concept, a prototype system is presented with a bulk laser diode/MOS driver operating at a wavelength of 870nm with a pulsing rate of 100kHz as the transmitter and a single-chip 9x9 SPAD array with 10-channel TDC as the receiver. The possibility of using this method as a solid-state solution to the task of 3D imaging is discussed in the light of the results derived from this prototype. PMID:27661900

  3. Development, testing, and initial space qualification of 1.5-μm high-power (6W) pulse-position-modulated (PPM) fiber laser transmitter for deep-space laser communication

    NASA Astrophysics Data System (ADS)

    Gupta, Shantanu; Engin, Doruk; Pachowicz, Dave; Fouron, Jean-Luc; Lander, Juan; Dang, Xung; Litvinovich, Slava; Chuang, Ti; Puffenberger, Kent; Kimpel, Frank; Utano, Rich; Wright, Malcolm

    2016-03-01

    We report on the development, testing and initial space qualification of a 1.5-μm, high-power (6W), high wall-plug efficiency (~15%), pulse-position-modulated (PPM), polarization-maintaining (PM), fiber laser transmitter subsystem for deep-space laser communication links. Programmable high-order PPM modulation up to PPM-128 formats, with discrete pulse slots ranging from 0.5- to 8-nsec, satisfies variety of link requirements for deep space laser communication to Mars, asteroids, and other deep-space relay links, per NASA's space laser communication roadmap. We also present initial space qualification results from thermal-vacuum tests, vibration testing, radiation testing and overall reliability assessment.

  4. Advances in High Energy Solid-State Pulsed 2-Micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael J.; Remus, Ruben

    2015-01-01

    NASA Langley Research Center has a long history of developing 2-micron lasers. From fundamental spectroscopy research, theoretical prediction of new materials, laser demonstration and engineering of lidar systems, it has been a very successful program spanning around two decades. Successful development of 2-micron lasers has led to development of a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement with an unprecedented laser pulse energy of 250 millijoules in a rugged package. This high pulse energy is produced by a Ho:Tm:LuLiF laser with an optical amplifier. While the lidar is meant for use as an airborne instrument, ground-based tests were carried out to characterize performance of the lidar. Atmospheric measurements will be presented, showing the lidar's capability for wind measurement in the atmospheric boundary layer and free troposphere. Lidar wind measurements are compared to a balloon sonde, showing good agreement between the two sensors. Similar architecture has been used to develop a high energy, Ho:Tm:YLF double-pulsed 2-micron Integrated Differential Absorption Lidar (IPDA) instrument based on direct detection technique that provides atmospheric column CO2 measurements. This instrument has been successfully used to measure atmospheric CO2 column density initially from a ground mobile lidar trailer, and then it was integrated on B-200 plane and 20 hours of flight measurement were made from an altitude ranging 1500 meters to 8000 meters. These measurements were compared to in-situ measurements and National Oceanic and Atmospheric Administration (NOAA) airborne flask measurement to derive the dry mixing ratio of the column CO2 by reflecting the signal by various reflecting surfaces such as land, vegetation, ocean surface, snow and sand. The lidar measurements when compared showed a very agreement with in-situ and airborne flask measurement. NASA Langley Research Center is currently developing a

  5. Development of a 2-micron Pulsed Differential Absorption Lidar for Atmospheric CO2 Concentration Measurement by Direct Detection Technique

    NASA Astrophysics Data System (ADS)

    Yu, J.; Singh, U. N.; Petros, M.; Bai, Y.

    2011-12-01

    Researchers at NASA Langley Research Center are developing a 2-micron Pulsed Differential Absorption Lidar instrument for ground and airborne measurements via direct detection method. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capbility by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement. A key component of the CO2 DIAL system, transceiver, is an existing, airborne ready, robust hardware which can provide 250mJ at 10Hz with double pulse format specifically designed for DIAL instrument. The exact wavelengths of the transceiver are controlled by well defined CW seed laser source to provide the required injection source for generating on-and-off line wavelength pulses sequentially. The compact, rugged, highly reliable transceiver is based on the unique Ho:Tm:YLF high-energy 2-micron pulsed laser technology. All the optical mounts are custom designed and have space heritage. They are designed to be adjustable and lockable and hardened to withstand vibrations that can occur in airborne operation. For the direct detection lidar application, a large primary mirror size is preferred. A 14 inch diameter telescope will be developed for this program. The CO2 DIAL/IPDA system requires many electronic functions to operate. These include diode, RF, seed laser, and PZT drivers; injection seeding detection and control; detector power supplies; and analog inputs to sample various sensors. Under NASA Laser Risk Reduction Program (LRRP), a control unit Compact Laser Electronics (CLE), is developed for the controlling the coherent wind lidar transceiver. Significant modifications and additions are needed to update it for CO2 lidar controls. The data acquisition system was built for ground CO2 measurement demonstration. The software will be updated for

  6. High Energy, Narrow Linewidth 1572nm Eryb-Fiber Based MOPA for a Multi-Aperture CO2 Trace-Gas Laser Space Transmitter

    NASA Technical Reports Server (NTRS)

    Engin, Doruk; Mathason, Brian; Stephen, Mark; Yu, Anthony; Cao, He; Fouron, Jean-Luc; Storm, Mark

    2016-01-01

    Accurate global measurements of tropospheric CO2 mixing ratios are needed to study CO2 emissions and CO2 exchange with the land and oceans. NASA Goddard Space Flight Center (GSFC) is developing a pulsed lidar approach for an integrated path differential absorption (IPDA) lidar to allow global measurements of atmospheric CO2 column densities from space. Our group has developed, and successfully flown, an airborne pulsed lidar instrument that uses two tunable pulsed laser transmitters allowing simultaneous measurement of a single CO2 absorption line in the 1570 nm band, absorption of an O2 line pair in the oxygen A-band (765 nm), range, and atmospheric backscatter profiles in the same path. Both lasers are pulsed at 10 kHz, and the two absorption line regions are sampled at typically a 300 Hz rate. A space-based version of this lidar must have a much larger lidar power-area product due to the x40 longer range and faster along track velocity compared to airborne instrument. Initial link budget analysis indicated that for a 400 km orbit, a 1.5 m diameter telescope and a 10 second integration time, a 2 mJ laser energy is required to attain the precision needed for each measurement. To meet this energy requirement, we have pursued parallel power scaling efforts to enable space-based lidar measurement of CO2 concentrations. These included a multiple aperture approach consists of multi-element large mode area fiber amplifiers and a single-aperture approach consists of a multi-pass Er:Yb:Phosphate glass based planar waveguide amplifier (PWA). In this paper we will present our laser amplifier design approaches and preliminary results.

  7. Investigation on crystalline perfection, optical transmittance, birefringence, temperature-dependent refractive index, laser damage threshold and pyroelectric characteristics of inversely soluble lithium sulfate monohydrate single crystals

    NASA Astrophysics Data System (ADS)

    Silambarasan, A.; Rajesh, P.; Bhatt, Rajeev; Bhaumik, Indranil; Karnal, A. K.; Ramasamy, P.; Gupta, P. K.

    2016-08-01

    Bulk prismatic lithium sulfate monohydrate (LSMH) single crystals were grown by seed rotation with slow heating method from aqueous solution. Small FWHM obtained from high-resolution X-ray diffraction spectrum shows that the crystals grown by this method have less defects and absence of low-angle grain boundaries. The high transmittance and low reflectance nature of the grown crystal was observed using UV-Vis-NIR spectrometer. The principal refractive indices of a LSMH crystal have been measured by a prism coupling method for the wavelengths of 0.407, 0.532, 0.828, 1.064 and 1.551 µm at room temperature, and Sellmeier equations are determined from the fitting of the data point. The refractive index data confirm that LSMH crystal is negative biaxial and the optic axis lies in YZ plane with an angle (2 V y ) of 51.74° with respect to y axis at 532 nm wavelength. The thermo-optic coefficients were determined from the temperature-dependent refractive indices measured in the range of 30-125 °C for the wavelengths of 532 and 1064 nm. The surface laser damage threshold studies reveal the higher optical radiation stability against 532-nm laser. The pyroelectric coefficients and pyroelectric figure of merit were determined from the pyroelectric current measurement by the Byer and Roundy method.

  8. Airborne 2-Micron Double Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurement

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan; Murchison, Luke

    2015-01-01

    An airborne 2-micron double-pulsed Integrated Path Differential Absorption (IPDA) lidar has been developed for atmospheric CO2 measurements. This new 2-miron pulsed IPDA lidar has been flown in spring of 2014 for total ten flights with 27 flight hours. It provides high precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement.

  9. Airborne 2-Micron Double Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurement

    NASA Astrophysics Data System (ADS)

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan; Murchison, Luke

    2016-06-01

    An airborne 2-micron double-pulsed Integrated Path Differential Absorption (IPDA) lidar has been developed for atmospheric CO2 measurements. This new instrument has been flown in spring of 2014 for a total of ten flights with 27 flight hours. This IPDA lidar provides high precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the results.

  10. High energy pulsed fiber laser transmitters in the C- and L-band for coherent lidar applications

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Moor, Nick; Petersen, Eliot B.; Nguyen, Dan T.; Yao, Zhidong; Stephen, Mark A.; Chavez-Pirson, Arturo; Peyghambarian, Nasser

    2011-10-01

    We report a monolithic specialized high stimulated Brillouin scattering (SBS) threshold fiber laser/amplifier in the C and L band based on highly co-doped phosphate glass fibers. This represents an important new development for coherent LIDAR and remote sensing applications. By using single mode polarization-maintaining large core highly Er/Yb codoped phosphate fibers in the power amplifier stages, we have achieved the highest peak power of 2.02 kW at 1530 nm for 105 ns pulses with transform-limited linewidth, and with a corresponding pulse energy of about 0.212 mJ. The achieved high-energy pulses were frequency doubled by using a commercial periodically poled lithium niobate (PPLN) crystal, and the highest SHG peak power of 271 W has been achieved for the SHG pulses at 765 nm that can be used for oxygen coherent remote sensing. In the L band, more than 80 μJ fiber laser pulses at 1572 nm with 1-2 μs pulse width and transform-limited linewidth have been achieved by using a monolithic fiber laser system in MOPA configuration, which can be used for CO2 coherent remote sensing.

  11. Two Micron Laser Technology Advancements at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.

    2010-01-01

    An Independent Laser Review Panel set up to examine NASA s space-based lidar missions and the technology readiness of lasers appropriate for space-based lidars indicated a critical need for an integrated research and development strategy to move laser transmitter technology from low technical readiness levels to the higher levels required for space missions. Based on the review, a multiyear Laser Risk Reduction Program (LRRP) was initiated by NASA in 2002 to develop technologies that ensure the successful development of the broad range of lidar missions envisioned by NASA. This presentation will provide an overview of the development of pulsed 2-micron solid-state laser technologies at NASA Langley Research Center for enabling space-based measurement of wind and carbon dioxide.

  12. Laser diode-fiber link for the transmitter of the SOUT program and for the beacon of the Silex program

    NASA Astrophysics Data System (ADS)

    Malaise, Daniel; Gollier, Jacques

    1993-06-01

    The small optical user terminal (SOUT) is part of an experimental program of the European Space Agency, initiated by British Aerospace. One takes advantage of the high antenna gain obtainable at 830 nm to build a very small, lightweight, and comparatively low cost terminal, capable of communicating with SILEX, ESA's full scale optical telecommunication program. SPACEBEL is in charge of developing the transmitting chain of the SOUT, and demonstrating its performances on a breadboard model. In the first part of the paper, we describe the transmitting chain of SOUT, stressing the delicate optical link between the diode and the monomode fiber. In the second part of the paper, we report on the first measurement of the efficiency of the coupling between the laser diode and the fiber as measured on the engineering model of the flight design for the Silex Beacon.

  13. High energy, narrow linewidth 1572nm ErYb-fiber based MOPA for a multi-aperture CO2 trace-gas laser space transmitter

    NASA Astrophysics Data System (ADS)

    Engin, Doruk; Mathason, Brian; Stephen, Mark; Yu, Anthony; Cao, He; Fouron, Jean-Luc; Storm, Mark

    2016-03-01

    A cladding-pumped, LMA ErYb fiber-based, amplifier is presented for use in a LIDAR transmitter for remote sensing of atmospheric CO2 from space. The amplifier is optimized for high peak power, high efficiency, and narrow linewidth operation at 1572.3nm. Using highly reliable COTS components, the amplifier achieves 0.5kW peak power (440uJ pulse energy), 3.3W average power with transform limited (TL) linewidth and M2<1.3. The power amplifier supports a 30% increase in pulse energy when linewidth is increased to 100MHz. A preliminary conductively cooled laser optical module (LOM) concept has size 9x10x1.25 in (113 in3) and estimated weight of 7.2lb (3.2 kg). Energy scaling with pulse width up to 645uJ, 1.5usec is demonstrated. A novel doubleclad ErYb LMA fiber (30/250um) with high pump absorption (6 dB/m at 915nm) was designed, fabricated, and characterized for power scaling. The upgraded power amplifier achieves 0.8kW peak power (720uJ pulse energy) 5.4W average power with TL linewidth and M2<1.5.

  14. Highly reliable and efficient 1.5μm-fiber-MOPA-based, high-power laser transmitter for space communication

    NASA Astrophysics Data System (ADS)

    Engin, Doruk; Litvinovitch, Slava; Kimpel, Frank; Puffenberger, Kent; Dang, Xung; Fouron, Jean-Luc; Martin, Nigel; Storm, Mark; Gupta, Shantanu; Utano, Rich

    2014-06-01

    Fibertek has developed a space qualifiable, highly efficient, high power (<5W), fiber based 1.5um laser optical module (LOM). The transmitter achieves 6W average and <1kW peak power out of a 2m long single mode delivery fiber with 8nsec pulses and <6Ghz linewidth. Stimulated Brillouin Scattering (SBS) is managed by precise linewidth control and by use of LMA gain fiber in the power stage while maintaining the required diffraction limited, and highly polarized (PER<20dB) output. Size and weight of the built LOM are 8"x10"x2.375" and 3 kg, respectively. With improvements in the modulation scheme and component specification, achieved LOM electrical to optical efficiency is over 17.0%. Highly efficient operation is sustained for a wide range of pulse-position modulation (16 to 128-ary PPM) formats with pulse widths varying from 8nsec to 0.5nsec and operation temperature 10-50C. Pressure stress analysis, random vibration analysis and thermal analysis of the designed LOM predicts compliance with NASA GEVS levels for vibration and thermal cycling in a vacuum environment. System will undergo both thermal vacuum and vibration testing to validate the design.

  15. A 2-Micron Pulsed Integrated Path Differential Absorption Lidar Development For Atmospheric CO2 Concentration Measurements

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Petros, Mulugeta; Reithmaier, Karl; Bai, Yingxin; Trieu, Bo C.; Refaat, Tamer F.; Kavaya, Michael J.; Singh, Upendra N.

    2012-01-01

    A 2-micron pulsed, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric CO2 concentration measurements via direct detection method is being developed at NASA Langley Research Center. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capability by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement.

  16. Compact, Engineered 2-Micron Coherent Doppler Wind Lidar Prototype for Field and Airborne Evaluation

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Amzajerdian, Farzin; Koch, Grady J.

    2006-01-01

    The state-of-the-art 2-micron coherent Doppler wind lidar breadboard at NASA/LaRC will be engineered and compactly packaged consistent with future aircraft flights. The packaged transceiver will be integrated into a coherent Doppler wind lidar system test bed at LaRC. Atmospheric wind measurements will be made to validate the packaged technology. This will greatly advance the coherent part of the hybrid Doppler wind lidar solution to the need for global tropospheric wind measurements.

  17. InGaAsSb Detectors Characterization for 2-Micron CO2 Lidar/DIAL Applications

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Abedin, M. Nurul; Koch, Grady J.; Singh, Upendra N.

    2003-01-01

    Recent interest in monitoring atmospheric CO2 focuses attention on infrared remote sensing using the 2-micron lidar/differential absorption lidar (DIAL) technique. Quantum detectors are critical components in this technique, and many research efforts concentrate on developing such devices for the 2-micron wavelength. Characterization results of InGaAsSb quantum detectors for the 2-micron wavelength range are presented, including experimental setup and procedure. Detectors are prototype devices manufactured by using separate absorption and multiplication (SAM) structures. Characterization experiments include V-I measurements, spectral response and its variation with bias voltage and temperature, noise measurements, noise-equivalent-power (NEP) and detectivity calculations, and signal-to-noise ratio (SNR) estimation. A slight increase in the output signal occurred with increased bias voltage and was associated with a noise level increase. Cooling down the detectors reduces noise and shifts the cutoff wavelength to shorter values. Further improvement in the design and manufacturing process, by increasing the device gain and lowering its noise level, is necessary to meet the required CO2 lidar/DIAL specifications.

  18. InGaAsSb Detectors' Characterization for 2-Micron CO2 Lidar/DIAL Applications

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Abedin, M. Nurul; Koch, Grady J.; Singh, Upendra N.

    2003-01-01

    Recent interest in monitoring atmospheric CO2 focuses attention on infrared remote sensing using the 2-micron lidar/differential absorption lidar (DIAL) technique. Quantum detectors are critical components in this technique, and many research efforts concentrate on developing such devices for the 2-micron wavelength. Characterization results of InGaAsSb quantum detectors for the 2-micron wavelength range are presented, including experimental setup and procedure. Detectors are prototype devices manufactured by using separate absorption and multiplication (SAM) structures. Characterization experiments include V-I measurements, spectral response and its variation with bias voltage and temperature, noise measurements, noise-equivalent-power (NEP) and detectivity calculations, and signal-to-noise ratio (SNR) estimation. A slight increase in the output signal occurred with increased bias voltage and was associated with a noise level increase. Cooling down the detectors reduces noise and shifts the cutoff wavelength to shorter values. Further improvement in the design and manufacturing process, by increasing the device gain and lowering its noise level, is necessary to meet the required CO2 lidar/DIAL specifications.

  19. Computer Simulation of Global Profiles of Carbon Dioxide Using a Pulsed, 2-Micron, Coherent-Detection, Column-Content DIAL System

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Singh, Upendra N.; Koch, Grady J.; Yu, Jirong; Frehlich, Rod G.

    2009-01-01

    We present preliminary results of computer simulations of the error in measuring carbon dioxide mixing ratio profiles from earth orbit. The simulated sensor is a pulsed, 2-micron, coherent-detection lidar alternately operating on at least two wavelengths. The simulated geometry is a nadir viewing lidar measuring the column content signal. Atmospheric absorption is modeled using FASCODE3P software with the HITRAN 2004 absorption line data base. Lidar shot accumulation is employed up to the horizontal resolution limit. Horizontal resolutions of 50, 100, and 200 km are shown. Assuming a 400 km spacecraft orbit, the horizontal resolutions correspond to measurement times of about 7, 14, and 28 s. We simulate laser pulse-pair repetition frequencies from 1 Hz to 100 kHz. The range of shot accumulation is 7 to 2.8 million pulse-pairs. The resultant error is shown as a function of horizontal resolution, laser pulse-pair repetition frequency, and laser pulse energy. The effect of different on and off pulse energies is explored. The results are compared to simulation results of others and to demonstrated 2-micron operating points at NASA Langley.

  20. Simultaneous and Independent Measurement of Atmospheric Water Vapor and Carbon Dioxide using a Triple-Pulsed, 2-micron Airborne IPDA Lidar - A Feasibility Study

    NASA Astrophysics Data System (ADS)

    Singh, U. N.; Refaat, T. F.; Yu, J.; Petros, M.

    2013-12-01

    Water vapor (H2O) and carbon dioxide (CO2) are dominant greenhouse gases that are critical for Earth's radiation budget and global warming through the eco-system and the carbon cycle. NASA Langley Research Center (LaRC) has a strong heritage in atmospheric remote sensing of both gases using several instruments adopting various DIAL techniques. This communication presents a feasibility study for measuring both H2O and CO2 simultaneously and independently using a single instrument. This instrument utilizes the Integrated Path Differential Absorption (IPDA) lidar technique to measure the weighted-average column dry-air mixing ratios of CO2 (XCO2) and H2O (XH2O) independently and simultaneously from an airborne platform. The key component of this instrument is a tunable triple-pulse 2-micron laser. The three laser pulses are transmitted sequentially within a short time interval of 200 microsec. The wavelength of each of the laser pulses can be tuned separately. The IPDA receiver design is based on low-risk, commercially available components, including 300-micron diameter InGaAs 2-micron pin detector, a low-noise, high speed trans-impedance amplifier (TIA) and 12-bit 400 MHz digitizer.

  1. The Selection of Q-Switch for a 350mJ Air-borne 2-micron Wind Lidar

    NASA Technical Reports Server (NTRS)

    Petros, Mulugeta; Yu, Jirong; Trieu, Bo; Bai, Yingxin; Petzar, Paul; Singh, Upendra N.

    2008-01-01

    In the process of designing a coherent, high energy 2micron, Doppler wind Lidar, various types of Q-Switch materials and configurations have been investigated for the oscillator. Designing an oscillator with a relatively low gain laser material, presents challenges related to the management high internal circulating fluence due to high reflective output coupler. This problem is compounded by the loss of hold-off. In addition, the selection has to take into account the round trip optical loss in the resonator and the loss of hold-off. For this application, a Brewster cut 5mm aperture, fused silica AO Q-switch is selected. Once the Q-switch is selected various rf frequencies were evaluated. Since the Lidar has to perform in single longitudinal and transverse mode with transform limited line width, in this paper, various seeding configurations are presented in the context of Q-Switch diffraction efficiency. The master oscillator power amplifier has demonstrated over 350mJ output when the amplifier is operated in double pass mode and higher than 250mJ when operated in single pass configuration. The repetition rate of the system is 10Hz and the pulse length 200ns.

  2. Automated alexandrite transmitter for airborne DIAL experiments

    NASA Technical Reports Server (NTRS)

    Degnan, John J.

    1988-01-01

    An account is given of the performance characteristics and development status of an automated dual alexandrite laser transmitter that is to be carried aloft by NASA's ER-2 research aircraft for water vapor DIAL experiments; these efforts are part of NASA's Lidar Atmospheric Sensing Experiment (LASE). The LASE transmitter encompasses control unit, thermal unit, and two lamp driver unit subsystems. Major reductions in system size and weight relative to commercially available alexandrite lasers were necessary; a total weight of only 330 lbs has been achieved. Attention is given to subsystem flight test results.

  3. Measurements of absolute line intensities in carbon dioxide bands near 5.2 microns

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Benner, D. C.; Devi, V. M.

    1985-01-01

    A nonlinear least-squares spectral fitting procedure has been used to derive experimental absolute intensities for over 300 unblended lines belonging to twelve CO2 bands in the 5.2-micron region. The spectral data were recorded at 0.01/cm resolution and room temperature with the Fourier transform spectrometer in the McMath solar telescope complex at the National Solar Observatory on Kitt Peak and have a signal-to-rms noise ratio of 2000-4000. A natural sample of carbon dioxide was used as the sample gas. For each band, the measured line intensities have been analyzed to derive the vibrational band intensity and coefficients of the F factor. The results are compared to the values used to calculate the intensities in the 1982 Air Force Geophysics Laboratory line parameters compilation.

  4. Development of a Pulsed 2-Micron Integrated Path Differential Absorption Lidar for CO2 Measurement

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Refaat, Tamer

    2013-01-01

    Atmospheric carbon dioxide (CO2) is an important greenhouse gas that significantly contributes to the carbon cycle and global radiation budget on Earth. Active remote sensing of CO2 is important to address several limitations that contend with passive sensors. A 2-micron double-pulsed, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric CO2 concentration measurements via direct detection method is being developed at NASA Langley Research Center. This active remote sensing instrument will provide an alternate approach of measuring atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capability by having high signal-to-noise ratio level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement. Commercial, on the shelf, components are implemented for the detection system. Instrument integration will be presented in this paper as well as a background for CO2 measurement at NASA Langley research Center

  5. Modeling of InGaAsSb-Based Avalanche Photodetectors for 2-Micron Wavelengths

    NASA Technical Reports Server (NTRS)

    Joshi, Ravindra P.; Abedin, M. Nurul (Technical Monitor)

    2002-01-01

    The main focus of this research is to study and evaluate the potential of InGaAsSb-AlGaAsSb based 2 micron avalanche photo-detectors. The photodetector contains a separate absorption and multiplication region (SAM) structure. The analysis has mainly been done to understand the electrical response characteristics of the devices existing at NASA, and to evaluate alternate structures proposed. Calculating the current flow for the existing detector structure, on the basis of its energy band diagram, is important. This analysis also helps to find shortcomings in the existing detector structure. It is shown that, unfortunately, the existing structure cannot lead to strong multiplication or voltage dependent gain. Two alternate structures are suggested, that could overcome the inherent flaws, and help achieve improved performance. These devices are obtained through modifications of the original structure, which include varying the doping levels, and changing the thicknesses of detector sub-regions. The results of our study are presented and discussed.

  6. Space-Based Erbium-Doped Fiber Amplifier Transmitters for Coherent, Ranging, 3D-Imaging, Altimetry, Topology, and Carbon Dioxide Lidar and Earth and Planetary Optical Laser Communications

    NASA Astrophysics Data System (ADS)

    Storm, Mark; Engin, Doruk; Mathason, Brian; Utano, Rich; Gupta, Shantanu

    2016-06-01

    This paper describes Fibertek, Inc.'s progress in developing space-qualified Erbium-doped fiber amplifier (EDFA) transmitters for laser communications and ranging/topology, and CO2 integrated path differential absorption (IPDA) lidar. High peak power (1 kW) and 6 W of average power supporting multiple communications formats has been demonstrated with 17% efficiency in a compact 3 kg package. The unit has been tested to Technology Readiness Level (TRL) 6 standards. A 20 W EDFA suitable for CO2 lidar has been demonstrated with ~14% efficiency (electrical to optical [e-o]) and its performance optimized for 1571 nm operation.

  7. Spacecraft transmitter reliability

    NASA Technical Reports Server (NTRS)

    1980-01-01

    A workshop on spacecraft transmitter reliability was held at the NASA Lewis Research Center on September 25 and 26, 1979, to discuss present knowledge and to plan future research areas. Since formal papers were not submitted, this synopsis was derived from audio tapes of the workshop. The following subjects were covered: users' experience with space transmitters; cathodes; power supplies and interfaces; and specifications and quality assurance. A panel discussion ended the workshop.

  8. Laser Energy Monitor for Double-Pulsed 2-Micrometer IPDA Lidar Application

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Petros, Mulugeta; Remus, Ruben; Yu, Jirong; Singh, Upendra N.

    2014-01-01

    Integrated path differential absorption (IPDA) lidar is a remote sensing technique for monitoring different atmospheric species. The technique relies on wavelength differentiation between strong and weak absorbing features normalized to the transmitted energy. 2-micron double-pulsed IPDA lidar is best suited for atmospheric carbon dioxide measurements. In such case, the transmitter produces two successive laser pulses separated by short interval (200 microseconds), with low repetition rate (10Hz). Conventional laser energy monitors, based on thermal detectors, are suitable for low repetition rate single pulse lasers. Due to the short pulse interval in double-pulsed lasers, thermal energy monitors underestimate the total transmitted energy. This leads to measurement biases and errors in double-pulsed IPDA technique. The design and calibration of a 2-micron double-pulse laser energy monitor is presented. The design is based on a high-speed, extended range InGaAs pin quantum detectors suitable for separating the two pulse events. Pulse integration is applied for converting the detected pulse power into energy. Results are compared to a photo-electro-magnetic (PEM) detector for impulse response verification. Calibration included comparing the three detection technologies in single-pulsed mode, then comparing the pin and PEM detectors in double-pulsed mode. Energy monitor linearity will be addressed.

  9. Remote sensing of turbulence in the clear atmosphere with 2-micron lidars

    NASA Technical Reports Server (NTRS)

    Martinson, Robert J.; Flint, John H.

    1994-01-01

    The development of an eye-safe, airborne LIDAR that exploits the decorrelation of the heterodyne signal to detect clear air turbulence is reported. A one watt average power transmitter is capable of detecting clear air turbulence to over 20 km is subvisual cirrus (an environment highly correlated with instabilities of sratified shear layers). In the absence of subvisual cirrus, a 4 km detection range is maintained. A table depicting the warning time in seconds with respect to the aircraft speed and instrument range (in kilometers) is presented.

  10. Column CO2 Measurement From an Airborne Solid-State Double-Pulsed 2-Micron Integrated Path Differential Absorption Lidar

    NASA Technical Reports Server (NTRS)

    Singh, U. N.; Yu, J.; Petros, M.; Refaat, T. F.; Remus, R.; Fay, J.; Reithmaier, K.

    2014-01-01

    NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micrometers IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

  11. Design of a fiber-optic transmitter for microwave analog transmission with high phase stability

    NASA Technical Reports Server (NTRS)

    Logan, R. T., Jr.; Lutes, G. F.; Primas, L. E.; Maleki, L.

    1990-01-01

    The principal considerations in the design of fiber-optic transmitters for highly phase-stable radio frequency and microwave analog transmission are discussed. Criteria for a fiber-optic transmitter design with improved amplitude and phase-noise performance are developed through consideration of factors affecting the phase noise, including low-frequency laser-bias supply noise, the magnitude and proximity of external reflections into the laser, and temperature excursions of the laser-transmitter package.

  12. Borehole induction coil transmitter

    SciTech Connect

    Holladay, Gale; Wilt, Michael J.

    2002-01-01

    A borehole induction coil transmitter which is a part of a cross-borehole electromagnetic field system that is used for underground imaging applications. The transmitter consists of four major parts: 1) a wound ferrite or mu-metal core, 2) an array of tuning capacitors, 3) a current driver circuit board, and 4) a flux monitor. The core is wound with several hundred turns of wire and connected in series with the capacitor array, to produce a tuned coil. This tuned coil uses internal circuitry to generate sinusoidal signals that are transmitted through the earth to a receiver coil in another borehole. The transmitter can operate at frequencies from 1-200 kHz and supplies sufficient power to permit the field system to operate in boreholes separated by up to 400 meters.

  13. Acquisition signal transmitter

    NASA Technical Reports Server (NTRS)

    Friedman, Morton L. (Inventor)

    1989-01-01

    An encoded information transmitter which transmits a radio frequency carrier that is amplitude modulated by a constant frequency waveform and thereafter amplitude modulated by a predetermined encoded waveform, the constant frequency waveform modulated carrier constituting an acquisition signal and the encoded waveform modulated carrier constituting an information bearing signal, the acquisition signal providing enhanced signal acquisition and interference rejection favoring the information bearing signal. One specific application for this transmitter is as a distress transmitter where a conventional, legislated audio tone modulated signal is transmitted followed first by the acquisition signal and then the information bearing signal, the information bearing signal being encoded with, among other things, vehicle identification data. The acquistion signal enables a receiver to acquire the information bearing signal where the received signal is low and/or where the received signal has a low signal-to-noise ratio in an environment where there are multiple signals in the same frequency band as the information bearing signal.

  14. Emergency locating transmitter

    NASA Technical Reports Server (NTRS)

    Wren, Paul E. (Inventor)

    1991-01-01

    A transmitter generates three signals for sequential transmission. These signal are an unmodulated r.f. carrier, a r.f. carrier amplitude modulated by a first audio frequency waveform and a r.f. carrier amplitude modulated by a second audio frequency waveform which is distinguishable from the first and which may be employed as a means for identifying a particular transmitter. The composite, sequentially transmitted signal may be varied in terms of the individual signal transmission sequence, the duration of the individual signals, overall composite signal repetition rate and the frequency of the second audio waveform. Various combinations of signal variations may be employed to transmit different information.

  15. Strain gage barometric transmitter

    NASA Technical Reports Server (NTRS)

    Viton, P.

    1977-01-01

    A strain gage barometric transmitter for measuring the atmospheric pressure in severe environmental conditions is described. This equipment specifications are presented and its performance assessed. It is shown that this barometric sensor can measure the atmospheric pressure with a precision of 0.5 mb during a 6 month period.

  16. A space-qualified transmitter system for heterodyne optical communications

    NASA Astrophysics Data System (ADS)

    McDonough, D. F.; Taylor, J. A.; Pillsbury, A. D.; Verly, D. P.; Kintzer, E. S.

    A space-based optical communications system requires the development of high-precision yet rugged electrooptical hardware. As part of a program to develop this technology, Lincoln Laboratory has designed and constructed a laser transmitter and a companion diagnostics module that have passed a rigorous space-qualification test program. The transmitter and diagnostics module are critical components of a satellite-to-satellite, 220 Mb/sec heterodyne communications experiment. The transmitter includes four redundant 30-mW diode lasers in a compact, lightweight package. The diagnostics module enables precise and autonomous setting of the transmitter laser power, wavelength, and modulation characteristics. The successful qualification of these components is a first, and a major milestone in the development of spaceborne optical communications systems.

  17. Micropulse water vapor differential absorption lidar: transmitter design and performance.

    PubMed

    Nehrir, Amin R; Repasky, Kevin S; Carlsten, John L

    2012-10-22

    An all diode-laser-based micropulse differential absorption lidar (DIAL) laser transmitter for tropospheric water vapor and aerosol profiling is presented. The micropulse DIAL (MPD) transmitter utilizes two continuous wave (cw) external cavity diode lasers (ECDL) to seed an actively pulsed, overdriven tapered semiconductor optical amplifier (TSOA). The MPD laser produces up to 7 watts of peak power over a 1 µs pulse duration (7 µJ) and a 10 kHz pulse repetition frequency. Spectral switching between the online and offline seed lasers is achieved on a 1Hz basis using a fiber optic switch to allow for more accurate sampling of the atmospheric volume between the online and offline laser shots. The high laser spectral purity of greater than 0.9996 coupled with the broad tunability of the laser transmitter will allow for accurate measurements of tropospheric water vapor in a wide range of geographic locations under varying atmospheric conditions. This paper describes the design and performance characteristics of a third generation MPD laser transmitter with enhanced laser performance over the previous generation DIAL system.

  18. Micropulse water vapor differential absorption lidar: transmitter design and performance.

    PubMed

    Nehrir, Amin R; Repasky, Kevin S; Carlsten, John L

    2012-10-22

    An all diode-laser-based micropulse differential absorption lidar (DIAL) laser transmitter for tropospheric water vapor and aerosol profiling is presented. The micropulse DIAL (MPD) transmitter utilizes two continuous wave (cw) external cavity diode lasers (ECDL) to seed an actively pulsed, overdriven tapered semiconductor optical amplifier (TSOA). The MPD laser produces up to 7 watts of peak power over a 1 µs pulse duration (7 µJ) and a 10 kHz pulse repetition frequency. Spectral switching between the online and offline seed lasers is achieved on a 1Hz basis using a fiber optic switch to allow for more accurate sampling of the atmospheric volume between the online and offline laser shots. The high laser spectral purity of greater than 0.9996 coupled with the broad tunability of the laser transmitter will allow for accurate measurements of tropospheric water vapor in a wide range of geographic locations under varying atmospheric conditions. This paper describes the design and performance characteristics of a third generation MPD laser transmitter with enhanced laser performance over the previous generation DIAL system. PMID:23187280

  19. A Compact Ti:Sapphire Laser With its Third Harmonic Generation (THG) for an Airborne Ozone Differential Absorption Lidar (DIAL) Transmitter

    NASA Technical Reports Server (NTRS)

    Chen, Songsheng; Storm, Mark E.; Marsh, Waverly D.; Petway, Larry B.; Edwards, William C.; Barnes, James C.

    2000-01-01

    A compact and high-pulse-energy Ti:Sapphire laser with its Third Harmonic Generation (THG) has been developed for an airborne ozone differential absorption lidar (DIAL) to study the distributions and concentrations of the ozone throughout the troposphere. The Ti:Sapphire laser, pumped by a frequency-doubled Nd:YAG laser and seeded by a single mode diode laser, is operated either at 867 nm or at 900 nm with a pulse repetition frequency of 20 Hz. High energy laser pulses (more than 110 mJ/pulse) at 867 nm or 900 nm with a desired beam quality have been achieved and utilized to generate its third harmonic at 289nm or 300nm, which are on-line and off-line wavelengths of an airborne ozone DIAL. After being experimentally compared with Beta-Barium Borate (beta - BaB2O4 or BBO) nonlinear crystals, two Lithium Triborate (LBO) crystals (5 x 5 x 20 cu mm) are selected for the Third Harmonic Generation (THG). In this paper, we report the Ti:Sapphire laser at 900 nm and its third harmonic at 300 nm. The desired high ultraviolet (UV) output pulse energy is more than 30 mJ at 300 nm and the energy conversion efficiency from 900 nm to 300 nm is 30%.

  20. Development of a Compact, Pulsed, 2-Micron, Coherent-Detection, Doppler Wind Lidar Transceiver; and Plans for Flights on NASA's DC-8 and WB-57 Aircraft

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Singh, Upendra N.; Koch, Grady J.; Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Petzar, Paul J.

    2009-01-01

    We present results of a recently completed effort to design, fabricate, and demonstrate a compact lidar transceiver for coherent-detection lidar profiling of winds. The novel high-energy, 2-micron, Ho:Tm:LuLiF laser technology developed at NASA Langley was employed to permit study of the laser technology currently envisioned by NASA for global coherent Doppler lidar measurement of winds in the future. The 250 mJ, 10 Hz compact transceiver was also designed for future aircraft flight. Ground-based wind profiles made with this transceiver will be presented. NASA Langley is currently funded to build complete Doppler lidar systems using this transceiver for the DC-8 and WB-57 aircraft. The WB-57 flights will present a more severe environment and will require autonomous operation of the lidar system. The DC-8 lidar system is a likely component of future NASA hurricane research. It will include real-time data processing and display, as well as full data archiving. We will attempt to co-fly on both aircraft with a direct-detection Doppler wind lidar system being prepared by NASA Goddard Space Flight Center.

  1. Temperature responsive transmitter

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L. (Inventor)

    1987-01-01

    A temperature responsive transmitter is provided in which frequency varies linearly with temperature. The transmitter includes two identically biased transistors connected in parallel. A capacitor, which reflects into the common bases to generate negative resistance effectively in parallel with the capacitor, is connected to the common emitters. A crystal is effectively in parallel with the capacitor and the negative resistance. Oscillations occur if the magnitude of the absolute value of the negative resistance is less than the positive resistive impedance of the capacitor and the inductance of the crystal. The crystal has a large linear temperature coefficient and a resonant frequency which is substantially less than the gain-bandwidth product of the transistors to ensure that the crystal primarily determines the frequency of oscillation. A high-Q tank circuit having an inductor and a capacitor is connected to the common collectors to increase the collector current flow which in turn enhances the radiation of the oscillator frequency by the inductor.

  2. Distributed data transmitter

    DOEpatents

    Brown, Kenneth Dewayne; Dunson, David

    2008-06-03

    A distributed data transmitter (DTXR) which is an adaptive data communication microwave transmitter having a distributable architecture of modular components, and which incorporates both digital and microwave technology to provide substantial improvements in physical and operational flexibility. The DTXR has application in, for example, remote data acquisition involving the transmission of telemetry data across a wireless link, wherein the DTXR is integrated into and utilizes available space within a system (e.g., a flight vehicle). In a preferred embodiment, the DTXR broadly comprises a plurality of input interfaces; a data modulator; a power amplifier; and a power converter, all of which are modularly separate and distinct so as to be substantially independently physically distributable and positionable throughout the system wherever sufficient space is available.

  3. Distributed data transmitter

    DOEpatents

    Brown, Kenneth Dewayne; Dunson, David

    2006-08-08

    A distributed data transmitter (DTXR) which is an adaptive data communication microwave transmitter having a distributable architecture of modular components, and which incorporates both digital and microwave technology to provide substantial improvements in physical and operational flexibility. The DTXR has application in, for example, remote data acquisition involving the transmission of telemetry data across a wireless link, wherein the DTXR is integrated into and utilizes available space within a system (e.g., a flight vehicle). In a preferred embodiment, the DTXR broadly comprises a plurality of input interfaces; a data modulator; a power amplifier; and a power converter, all of which are modularly separate and distinct so as to be substantially independently physically distributable and positionable throughout the system wherever sufficient space is available.

  4. Orbiter KU-band transmitter

    NASA Technical Reports Server (NTRS)

    Halterman, R.

    1976-01-01

    The design, build, and test of an engineering breadboard Ku band quadraphase shift keyed and wideband frequency modulated transmitter are described. This orbiter Ku band transmitter drawer is to simulate the orbiter transmitter and meet the functional requirements of the orbiter communication link.

  5. Noise Whitening in Airborne Wind Profiling With a Pulsed 2-Micron Coherent Doppler Lidar at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Beyon, Jeffrey Y.; Arthur, Grant E.; Koch, Grady J.; Kavaya, Michael J.

    2012-01-01

    Two different noise whitening methods in airborne wind profiling with a pulsed 2-micron coherent Doppler lidar system at NASA Langley Research Center in Virginia are presented. In order to provide accurate wind parameter estimates from the airborne lidar data acquired during the NASA Genesis and Rapid Intensification Processes (GRIP) campaign in 2010, the adverse effects of background instrument noise must be compensated properly in the early stage of data processing. The results of the two methods are presented using selected GRIP data and compared with the dropsonde data for verification purposes.

  6. Airborne Wind Profiling With the Data Acquisition and Processing System for a Pulsed 2-Micron Coherent Doppler Lidar System

    NASA Technical Reports Server (NTRS)

    Beyon, Jeffrey Y.; Koch, Grady J.; Kavaya, Michael J.

    2012-01-01

    A pulsed 2-micron coherent Doppler lidar system at NASA Langley Research Center in Virginia flew on the NASA's DC-8 aircraft during the NASA Genesis and Rapid Intensification Processes (GRIP) during the summer of 2010. The participation was part of the project Doppler Aerosol Wind Lidar (DAWN) Air. Selected results of airborne wind profiling are presented and compared with the dropsonde data for verification purposes. Panoramic presentations of different wind parameters over a nominal observation time span are also presented for selected GRIP data sets. The realtime data acquisition and analysis software that was employed during the GRIP campaign is introduced with its unique features.

  7. Absolute integrated intensity and individual line parameters for the 6.2-micron band of NO2. [in solar spectrum

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Bonomo, F. S.; Williams, W. J.; Murcray, D. G.; Snider, D. E.

    1975-01-01

    The absolute integrated intensity of the 6.2-micron band of NO2 at 40 C was determined from quantitative spectra at about 10 per cm resolution by the spectral band model technique. A value of 1430 plus or minus 300 per sq cm per atm was obtained. Individual line parameters, positions, intensities, and ground-state energies were derived, and line-by-line calculations were compared with the band model results and with the quantitative spectra obtained at about 0.5 per cm resolution.

  8. Development of the Data Acquisition and Processing System for a Pulsed 2-Micron Coherent Doppler Lidar System

    NASA Technical Reports Server (NTRS)

    Beyon, Jeffrey Y.; Koch, Grady J.; Kavaya, Michael J.

    2010-01-01

    A general overview of the development of a data acquisition and processing system is presented for a pulsed, 2-micron coherent Doppler Lidar system located in NASA Langley Research Center in Hampton, Virginia, USA. It is a comprehensive system that performs high-speed data acquisition, analysis, and data display both in real time and offline. The first flight missions are scheduled for the summer of 2010 as part of the NASA Genesis and Rapid Intensification Processes (GRIP) campaign for the study of hurricanes. The system as well as the control software is reviewed and its requirements and unique features are discussed.

  9. Broadband 7 microns OPCPA pumped by a 2 microns picosecond Ho:YLF CPA system

    NASA Astrophysics Data System (ADS)

    Sanchez, Daniel; Hemmer, Michael; Baudisch, Matthias; Biegert, Jens; Chalus, Olivier; Simon-Boisson, Christophe; Zawilski, Kevin; Schunemann, Peter G.; Smirnov, Vadim; Hoogland, Heinar

    2016-03-01

    The development of coherent light sources with emission in the mid-IR is currently undergoing a remarkable revolution. The mid-IR spectral range has always been of tremendous interest, mainly to spectroscopists, due to the ability of mid-IR light to access rotational and vibrational resonances of molecules which give rise to superb sensitivity upon optical probing [1-3]. Previously, high energy resolution was achieved with narrowband lasers or parametric sources, but the advent of frequency comb sources has revolutionized spectroscopy by providing high energy resolution within the frequency comb structure of the spectrum and at the same time broadband coverage and short pulse duration [4-6]. Such carrier to envelope phase (CEP) controlled light waveforms, when achieved at ultrahigh intensity, give rise to extreme effects such as the generation of isolated attosecond pulses in the vacuum to extreme ultraviolet range (XUV) [7]. Motivated largely by the vast potential of attosecond science, the development of ultraintense few-cycle and CEP stable sources has intensified [8], and it was recognized that coherent soft X-ray radiation could be generated when driving high harmonic generation (HHG) with long wavelength sources [9-11]. Recently, based on this concept, the highest waveform controlled soft X-ray flux [12] and isolated attosecond pulse emission at 300 eV [13] was demonstrated via HHG from a 1850 nm, sub-2-cycle source [14]. Within strong field physics, long wavelength scaling may lead to further interesting physics such as the direct reshaping of the carrier field [15], scaling of quantum path dynamics [16], the breakdown of the dipole approximation [17] or direct laser acceleration [18]. The experimental development of long wavelength light sources therefore holds great promise in many fields of science and will lead to numerous applications beyond strong field physics and attosecond science. In this paper, we present the first mid-IR optical parametric

  10. Optimization of A 2-Micron Laser Frequency Stabilization System for a Double-Pulse CO2 Differential Absorption Lidar

    NASA Technical Reports Server (NTRS)

    Chen, Songsheng; Yu, Jirong; Bai, Yingsin; Koch, Grady; Petros, Mulugeta; Trieu, Bo; Petzar, Paul; Singh, Upendra N.; Kavaya, Michael J.; Beyon, Jeffrey

    2010-01-01

    A carbon dioxide (CO2) Differential Absorption Lidar (DIAL) for accurate CO2 concentration measurement requires a frequency locking system to achieve high frequency locking precision and stability. We describe the frequency locking system utilizing Frequency Modulation (FM), Phase Sensitive Detection (PSD), and Proportional Integration Derivative (PID) feedback servo loop, and report the optimization of the sensitivity of the system for the feed back loop based on the characteristics of a variable path-length CO2 gas cell. The CO2 gas cell is characterized with HITRAN database (2004). The method can be applied for any other frequency locking systems referring to gas absorption line.

  11. Active Stand-off Detection of Gas Leaks Using a Short Range Hard-target Backscatter Differential Optical Absorption System Based on a Quantum Cascade Laser Transmitter

    NASA Astrophysics Data System (ADS)

    Diaz, Adrian; Thomas, Benjamin; Castillo, Paulo; Gross, Barry; Moshary, Fred

    2016-06-01

    Fugitive gas emissions from agricultural or industrial plants and gas pipelines are an important environmental concern as they can contribute to the global increase of greenhouse gas concentration. Moreover, they are also a security and safety concern because of possible risk of fire/explosion or toxicity. This study presents gas concentration measurements using a quantum cascade laser open path system (QCLOPS). The system retrieves the pathaveraged concentration of N2O and CH4 by collecting the backscattered light from a scattering target. The gas concentration measurements have a high temporal resolution (68 ms) and are achieved at sufficient range (up to 40 m, ~ 130 feet) with a detection limit of 2.6 ppm CH4 and 0.4 ppm for N2O. Given these characteristics, this system is promising for mobile/multidirectional remote detection and evaluation of gas leaks. The instrument is monostatic with a tunable QCL emitting at ~ 7.7 μm wavelength range. The backscattered radiation is collected by a Newtonian telescope and focused on an infrared light detector. Puffs of N2O and CH4 are released along the optical path to simulate a gas leak. The measured absorption spectrum is obtained using the thermal intra-pulse frequency chirped DFB QCL and is analyzed to obtain path averaged gas concentrations.

  12. 47 CFR 74.461 - Transmitter power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Transmitter power. 74.461 Section 74.461....461 Transmitter power. (a) Transmitter power is the power at the transmitter output terminals and.... For the purpose of this Subpart, the transmitter power is the carrier power. (b) The...

  13. 47 CFR 74.461 - Transmitter power.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Transmitter power. 74.461 Section 74.461....461 Transmitter power. (a) Transmitter power is the power at the transmitter output terminals and.... For the purpose of this Subpart, the transmitter power is the carrier power. (b) The...

  14. 47 CFR 74.461 - Transmitter power.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Transmitter power. 74.461 Section 74.461....461 Transmitter power. (a) Transmitter power is the power at the transmitter output terminals and.... For the purpose of this Subpart, the transmitter power is the carrier power. (b) The...

  15. 47 CFR 74.461 - Transmitter power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Transmitter power. 74.461 Section 74.461....461 Transmitter power. (a) Transmitter power is the power at the transmitter output terminals and.... For the purpose of this Subpart, the transmitter power is the carrier power. (b) The...

  16. 47 CFR 74.461 - Transmitter power.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Transmitter power. 74.461 Section 74.461....461 Transmitter power. (a) Transmitter power is the power at the transmitter output terminals and.... For the purpose of this Subpart, the transmitter power is the carrier power. (b) The...

  17. Airborne Wind Profiling Algorithms for the Pulsed 2-Micron Coherent Doppler Lidar at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Beyon, Jeffrey Y.; Koch, Grady J.; Kavaya, Michael J.; Ray, Taylor J.

    2013-01-01

    Two versions of airborne wind profiling algorithms for the pulsed 2-micron coherent Doppler lidar system at NASA Langley Research Center in Virginia are presented. Each algorithm utilizes different number of line-of-sight (LOS) lidar returns while compensating the adverse effects of different coordinate systems between the aircraft and the Earth. One of the two algorithms APOLO (Airborne Wind Profiling Algorithm for Doppler Wind Lidar) estimates wind products using two LOSs. The other algorithm utilizes five LOSs. The airborne lidar data were acquired during the NASA's Genesis and Rapid Intensification Processes (GRIP) campaign in 2010. The wind profile products from the two algorithms are compared with the dropsonde data to validate their results.

  18. Development of Numerical Models for Performance Predictions of Single-Photon Avalanche Photodetectors (SPAP) for the 2-Micron Regime

    NASA Technical Reports Server (NTRS)

    Joshi, Ravindra P.; Abedin, M. Nurul (Technical Monitor)

    2001-01-01

    Field dependent drift velocity results are presented for electron transport in bulk Indium Arsenide (InAs) material based on a Monte Carlo model, which includes an analytical treatment of band-to-band impact ionization. Avalanche multiplication and related excess noise factor (F) are computed as a function of device length and applied voltage. A decrease in F with increases in device length is obtained. The results suggest an inherent utility for InAs-based single-photon avalanche detectors, particularly around the 2 microns region of interest for atmospheric remote sensing applications. The dark current response was also evaluated. The role of the various components has been analyzed. For shorter devices, the tunneling component is shown to dominate at low temperatures. Finally, possible structures for enhanced photodetection are proposed for future research.

  19. Transmittance through anthropogenic dust clouds.

    PubMed

    Seagraves, M A; Duncan, L D

    1981-07-01

    Measurements of transmittance through dust and debris clouds generated by explosions and moving vehicles from five field tests involving 120 trials were analyzed to determine the degree to which transmittance is wavelength dependent. Statistical tests to determine whether the amounts of time transmittance were reduced to specified levels that were significantly different for various wavelengths revealed, in general, no consistent wavelength dependence. Relationships between the extinction coefficient for IR spectral and visible regions have been established for specific explosive types and soil conditions involved in some of these tests.

  20. An ingestible temperature-transmitter

    NASA Technical Reports Server (NTRS)

    Pope, J. M.; Fryer, T. B.; Sandler, H.

    1972-01-01

    Pill-sized transmitter measures deep body temperature in studies of circadian rhythm and indicates general health. Ingestible device is a compromise between accuracy, circuit complexity, size and transmission range.

  1. Transport of majority and minority carriers in 2-micron-diameter Pt-GaAs Schottky barriers

    NASA Technical Reports Server (NTRS)

    Chan, E. Y.; Card, H. C.; Yang, E. S.; Kerr, A. R.; Mattauch, R. J.

    1979-01-01

    An experimental study of small area (2-micron diameter) Pt-GaAs Schottky barrier diodes has been made, by using a wafer chip with a matrix of these diodes lying within approximately a minority carrier diffusion length of one another. Using one diode as collector and another as emitter, transistor measurements indicated that the dominant contribution to the current is the majority-carrier thermionic field emission current for large forward-bias voltage of the emitter junction (V-EB no less than about 0.4 V), whereas the smaller forward-bias (V-EB no greater than about 0.4 V) recombination in the space-charge region was most important. The minority carrier injection ratio is measurable only for large forward-bias voltages, decreasing from about 0.02 to 0.00001 as VEB increases from 0.5 to 1.0 V. The minority carrier diffusion length was measured to be about 1.3 microns. These results are of considerable significance for the understanding and optimization of the performance of these devices as classical detectors and mixers.

  2. Proposal to Simultaneously Profile Wind and CO2 on Earth and Mars With 2-micron Pulsed Lidar Technologies

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Koch, Grady J.; Kavaya, Michael J.; Amzajerdian, Farzin; Ismail, Syed; Emmitt, David

    2005-01-01

    2-micron lidar technology has been in use and under continued improvement for many years toward wind measurements. But the 2-micron wavelength region is also rich in absorption lines of CO2 (and H2O to a lesser extent) that can be exploited with the differential absorption lidar (DIAL) technique to make species concentration measurements. A coherent detection receiver offers the possibility of making combined wind and DIAL measurements with wind derived from frequency shift of the backscatter spectrum and species concentration derived from power of the backscatter spectrum. A combined wind and CO2 measurement capability is of interest for applications on both Earth and Mars. CO2 measurements in the Earth atmosphere are of importance to studies of the global carbon cycle. Data on vertically-resolved CO2 profiles over large geographical observations areas are of particular interest that could potentially be made by deploying a lidar on an aircraft or satellite. By combining CO2 concentration with wind measurements an even more useful data product could be obtained in the calculation of CO2 flux. A challenge to lidar in this application is that CO2 concentration measurements must be made with a high level of precision and accuracy to better than 1%. The Martian atmosphere also presents wind and CO2 measurement problems that could be met with a combined DIAL/Doppler lidar. CO2 concentration in this scenario would be used to calculate atmospheric density since the Martian atmosphere is composed of 95% CO2. The lack of measurements of Mars atmospheric density in the 30-60 km range, dust storm formation and movements, and horizontal wind patterns in the 0-20 km range pose significant risks to aerocapture, and entry, descent, and landing of future robotic and human Mars missions. Systematic measurement of the Mars atmospheric density and winds will be required over several Mars years, supplemented with day-of-entry operational measurements. To date, there have been 5

  3. Modified transmitter attachment method for adult ducks

    USGS Publications Warehouse

    Pietz, P.J.; Brandt, D.A.; Krapu, G.L.; Buhl, D.A.

    1995-01-01

    The value of radio telemetry for waterfowl research depends on the availability of suitable methods of attaching transmitters. In previous studies, external transmitters attached to adult Mallards (Anas platyrhynchos) with sutures and glue did not stay on birds reliably. In an attempt to improve transmitter retention, a method of attachment was tested in which 4-g transmitters were attached mid-dorsally with sutures and with a stainless steel anchor-shaped wire inserted subcutaneously (anchor transmitters). Field tests indicated that all of 26 female Mallards and 63 of 65 female Gadwalls (Anas strepera) retained their anchor transmitters during 4369 bird-days of monitoring during nesting and brood rearing. Survival rates of females with anchor transmitters compared favorably with those reported from other studies. In this study, females with and without anchor transmitters did not differ with respect to survival rates of their ducklings. The anchor transmitter may be suitable for a variety of field studies on numerous species.

  4. A 20-GHz IMPATT transmitter

    NASA Technical Reports Server (NTRS)

    Chan, J. L.; Sun, C.

    1983-01-01

    The engineering development of a solid state transmitter amplifier operating in the 20 GHz frequency band. The development effort involved a variety of disciplines including IMPATT device development, circulator design, simple and multiple diode circuits designs, and amplifier integration and test.

  5. Reconfigurable optical transmitters and receivers

    NASA Astrophysics Data System (ADS)

    Freude, Wolfgang; Schmogrow, René; Hillerkuss, David; Meyer, Joachim; Dreschmann, Michael; Nebendahl, Bernd; Huebner, Michael; Becker, Juergen; Koos, Christian; Leuthold, Juerg

    2012-01-01

    Recent advances in electronic data processing allow constructing reconfigurable optical transmitters and receivers, where modulation formats and symbol rates are set by software-controlled field programmable gate arrays (FPGA). We report on such a real-time optical transmitter for 8 modulation formats, which can be swapped in 5 ns without data loss. With single-polarization 64QAM symbols generated at 28 GBd, we transmit data at 168 Gbit/s in real time. A similar arrangement defines a single-polarization orthogonal frequency division multiplexing (OFDM) transmitter for a data rate of 101.5 Gbit/s, where 58 subcarriers are encoded with 16QAM data. With a different software setup, the FPGA realizes an optical 56 Gbit/s transmitter for sinc-shaped so-called Nyquist pulses, the spectrum of which is rectangular having the minimum theoretically achievable bandwidth (suitable for Nyquist wavelength division multiplexing, N-WDM). For terabit OFDM reception, optical pre-processing is required to demultiplex high-bitrate signals down to lower-bitrate tributaries, which then can be processed electronically. We discuss a 10.8 Tbit/s (26 Tbit/s) receiver employing an all-optical fast Fourier transform to demultiplex 75 (325) optical subcarriers modulated with 16QAM-formated symbols at a rate of 18 GBd (10 GBd). Groups with any number of subcarriers can be selected with a simple hardware reconfiguration step.

  6. Lasers.

    ERIC Educational Resources Information Center

    Schewe, Phillip F.

    1981-01-01

    Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

  7. A Low Cost TDRSS Compatible Transmitter Option

    NASA Technical Reports Server (NTRS)

    Whiteman, Don

    2005-01-01

    The NASA Space-based Telemetry and Range Safety (STARS) program has developed and tested a low cost Ku-Band transmitter alternative for TDRSS applications based on an existing IRIG shaped offset quaternary phase shift keying (SOQPSK) transmitter. This paper presents information related to the implementation of this low cost system, as well as performance measurements of the alternative TDRSS transmitter system compared with an existing QPSK TDRSS transmitter.

  8. Transmitter data collection using Ada

    NASA Technical Reports Server (NTRS)

    Conroy, B. L.

    1988-01-01

    A data collection system installed on the 400 kilowatt X-band transmitter of the Goldstone Solar System Radar is described. The data collection system is built around the off-the-shelf IEEE 488 instrumentation, linked with fiber optics, controlled by an inexpensive computer, and uses software written in the Ada language. The speed and accuracy of the system is discussed, along with programming techniques used for both data collection and reduction.

  9. 47 CFR 80.215 - Transmitter power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Transmitter power. 80.215 Section 80.215... MARITIME SERVICES General Technical Standards § 80.215 Transmitter power. (a) Transmitter power shown on the radio station authorization is the maximum power the licensee is authorized to use. Power...

  10. 47 CFR 101.807 - Transmitter power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Transmitter power. 101.807 Section 101.807... SERVICES Local Television Transmission Service § 101.807 Transmitter power. Stations in this service will not be authorized to use transmitters having a rated power output in excess of the limits set forth...

  11. 47 CFR 101.513 - Transmitter power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Transmitter power. 101.513 Section 101.513... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.513 Transmitter power. The transmitter power will be governed by § 101.113. Further, each application must contain an analysis...

  12. 47 CFR 101.807 - Transmitter power.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Transmitter power. 101.807 Section 101.807... SERVICES Local Television Transmission Service § 101.807 Transmitter power. Stations in this service will not be authorized to use transmitters having a rated power output in excess of the limits set forth...

  13. 47 CFR 101.513 - Transmitter power.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Transmitter power. 101.513 Section 101.513... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.513 Transmitter power. The transmitter power will be governed by § 101.113. Further, each application must contain an analysis...

  14. 47 CFR 101.807 - Transmitter power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Transmitter power. 101.807 Section 101.807... SERVICES Local Television Transmission Service § 101.807 Transmitter power. Stations in this service will not be authorized to use transmitters having a rated power output in excess of the limits set forth...

  15. 47 CFR 101.513 - Transmitter power.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Transmitter power. 101.513 Section 101.513... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.513 Transmitter power. The transmitter power will be governed by § 101.113. Further, each application must contain an analysis...

  16. 47 CFR 80.215 - Transmitter power.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Transmitter power. 80.215 Section 80.215... MARITIME SERVICES General Technical Standards § 80.215 Transmitter power. (a) Transmitter power shown on the radio station authorization is the maximum power the licensee is authorized to use. Power...

  17. 47 CFR 80.215 - Transmitter power.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Transmitter power. 80.215 Section 80.215... MARITIME SERVICES General Technical Standards § 80.215 Transmitter power. (a) Transmitter power shown on the radio station authorization is the maximum power the licensee is authorized to use. Power...

  18. 47 CFR 80.215 - Transmitter power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Transmitter power. 80.215 Section 80.215... MARITIME SERVICES General Technical Standards § 80.215 Transmitter power. (a) Transmitter power shown on the radio station authorization is the maximum power the licensee is authorized to use. Power...

  19. 47 CFR 101.807 - Transmitter power.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Transmitter power. 101.807 Section 101.807... SERVICES Local Television Transmission Service § 101.807 Transmitter power. Stations in this service will not be authorized to use transmitters having a rated power output in excess of the limits set forth...

  20. 47 CFR 101.513 - Transmitter power.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Transmitter power. 101.513 Section 101.513... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.513 Transmitter power. The transmitter power will be governed by § 101.113. Further, each application must contain an analysis...

  1. 47 CFR 80.215 - Transmitter power.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Transmitter power. 80.215 Section 80.215... MARITIME SERVICES General Technical Standards § 80.215 Transmitter power. (a) Transmitter power shown on the radio station authorization is the maximum power the licensee is authorized to use. Power...

  2. 47 CFR 101.807 - Transmitter power.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Transmitter power. 101.807 Section 101.807... SERVICES Local Television Transmission Service § 101.807 Transmitter power. Stations in this service will not be authorized to use transmitters having a rated power output in excess of the limits set forth...

  3. Transparent polycrystalline body with high ultraviolet transmittance, process for making and applications thereof

    NASA Astrophysics Data System (ADS)

    Roy, Donald W.; Hastert, James L.; Coubrough, Lawrence; Green, Kenneth E.; Trujillo, Aurelio

    1993-12-01

    A sintered polycrystalline body is disclosed which consists essentially of magnesia alumina spinel having an in-line transmittance per 1.88 mm thickness of not less than about 62.5 percent at a wavelength of about 0.2 microns and not less than 85 percent at a wavelength of about 0.3 microns. The material retains at least about 90 percent of its original transmissivity after as much as 240 hours or more of exposure to ultraviolet light in the 0.2-0.4 micron wavelength range. The sintered body has a flexural strength of at least about 15,000 psi. The sintered transparent body can be produced by a two-step process in which a spinel powder is formed into a closed porosity body by hot pressing or pressureless sintering. The closed porosity body is then hot isostatic pressed at a temperature of at least about 1,400 C under a pressure of at least about 15,000 psi. The sintered body so produced has a grain size under about 150 microns, a porosity less than about 0.001 percent, and a transmittance previously specified. Substantially larger grain sizes result in reduced strength, while substantially smaller grain sizes result in unacceptable ultraviolet transmission. The invention relates in particular to a missile dome and a launch tube window which has high ultraviolet transmittance properties and is stable under high temperatures, corrosive environments, and resistant to abrasion or erosion.

  4. Control of optical transmittance of fat tissue slices at NIR photodynamic action mediated by indocyanine green

    NASA Astrophysics Data System (ADS)

    Yanina, I. Y.; Doubrovsky, V. A.; Tuchin, V. V.

    2013-02-01

    The changes in optical transmittance of human adipose cell layers sensitized by indocyanine green (ICG) as a result of photodynamic action were found and studied. It was revealed experimentally that due to the selective action of laser radiation on fat tissue sensitized by ICG the spatial distribution of its optical transmittance becomes more homogeneous. The statistical computer processing of digital images allowed one to estimate tissue optical transmittance, its spatial and temporal distributions. These quantitative estimations correlated well with the visible changes of tissue images. The measurements carried out gave an opportunity to suggest the interpretation of the phenomenon observed.

  5. Comparison of 2 micron Ho and 10 micron CO2 lidar for atmospheric backscatter and Doppler windshear detection

    NASA Technical Reports Server (NTRS)

    Killinger, Dennis

    1991-01-01

    The development of eye-safe, solid-state Lidar systems is discussed, with an emphasis on Coherent Doppler Lidar for Atmospheric Wind Measurements. The following subject areas are covered: tunable Ho DIAL (Differential Absorption Lidar)/lidar atmospheric measurements; atmospheric turbulence measurements and detector arrays; diurnal measurements of C(sub n)(sup 2) for KSC lidar measurements; and development of single-frequency Ho laser/lidar.

  6. Infrared heterodyne radiometer for airborne atmospheric transmittance measurements

    NASA Technical Reports Server (NTRS)

    Wolczok, J. M.; Lange, R. A.; Dinardo, A. J.

    1980-01-01

    An infrared heterodyne radiometer (IHR) was used to measure atmospheric transmittance at selected hydrogen fluoride (2.7 micrometer) and deuterium fluoride (3.8 micrometer) laser transitions. The IHR was installed aboard a KC-135 aircraft for an airborne atmospheric measurements program that used the sun as a backlighting source for the transmission measurements. The critical components are: a wideband indium antimonide (1nSb) photomixer, a CW HF/DF laser L0, a radiometric processor, and a 1900 K blackbody reference source. The measured heterodyne receiver sensitivity (NEP) is 1.3 x 10 to the -19th power W/Hz, which yields a calculated IHR temperature resolution accuracy of delta I sub S/-3 sub S = 0.005 for a source temperature of 1000 K and a total transmittance of 0.5. Measured atmospheric transmittance at several wavelengths and aircraft altitudes from 9.14 km (30,000 ft) to 13.72 km (45,000 ft) were obtained during the measurements program and have been compared with values predicted by the AFGL Atmospheric Line Parameter Compilation.

  7. Characteristics of direct detection 1.6μm CO2 DIAL with OPG transmitter

    NASA Astrophysics Data System (ADS)

    Nagasawa, C.; Shibata, Y.; Abo, M.

    2015-12-01

    In recent years, there have been significant advances in a QPM nonlinear optical frequency conversion efficienfy. The QPM condition is produced to use periodically poled ferroelectric crystals. An optical parametric oscillator (OPO), amplifier (OPA), and generator (OPG) devices are widely recognized as versatile coherent tunable spectroscopic sources. Many applications of PPLN-parametric radiation sources, such as laser remote sensing and molecular spectroscopy, require broadly tunable and narrow linewidth operation in the infrared region. We developed an optical parametric oscillator (OPO) transmitter for the first 1.6 μm CO2 DIAL. In order to improve the measurement accuracy of CO2 profiles, development of high power and wavelength stabilized laser system has been conducted. We have developed a new high-power 1.6 μm laser transmitter based on a parametric master oscillator-power amplifier (MOPA) system pumped by a LD-pumped Q-switched Nd:YAG laser which has the injection seed laser locked to the iodine absorption line. The master oscillator is the OPG transmitter and the amplifier is the OPA transmitter. Since the OPO transmitter has a cavity mirror, running the system without mode hopping requires complex control of cavity length. By contrast, the OPG transmitter has no cavity mirror, so there is no need to control cavity length. We report detail characteristics of the direct detection 1.6 μm CO2 DIAL with the OPG transmitter. Moreover, we report the technique of the simultaneously measurement temperature profiles with the CO2 concentration profiles using a CO2 absorption profile because of improvement of measurement accuracy of the CO2 concentration. This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and Technology Agency.

  8. Automatic frequency control for FM transmitter

    NASA Technical Reports Server (NTRS)

    Honnell, M. A. (Inventor)

    1974-01-01

    An automatic frequency control circuit for an FM television transmitter is described. The frequency of the transmitter is sampled during what is termed the back porch portion of the horizontal synchronizing pulse which occurs during the retrace interval, the frequency sample compared with the frequency of a reference oscillator, and a correction applied to the frequency of the transmitter during this portion of the retrace interval.

  9. A demonstration of CMOS VLSI circuit prototyping in support of the site facility using the 1.2 micron standard cell library developed by National Security Agency

    NASA Astrophysics Data System (ADS)

    Smith, Edwyn D.

    1991-03-01

    Two silicon CMOS application specific integrated circuits (ASICs), a data generation chip, and a data checker chip were designed. The conversion of the data generator circuitry into a pair of CMOS ASIC chips using the 1.2 micron standard cell library is documented. The logic design of the data checker is discussed. The functions of the control circuitry is described. An accurate estimate of timing relationships is essential to make sure that the logic design performs correctly under practical conditions. Timing and delay information are examined.

  10. A demonstration of CMOS VLSI circuit prototyping in support of the site facility using the 1.2 micron standard cell library developed by National Security Agency

    NASA Technical Reports Server (NTRS)

    Smith, Edwyn D.

    1991-01-01

    Two silicon CMOS application specific integrated circuits (ASICs), a data generation chip, and a data checker chip were designed. The conversion of the data generator circuitry into a pair of CMOS ASIC chips using the 1.2 micron standard cell library is documented. The logic design of the data checker is discussed. The functions of the control circuitry is described. An accurate estimate of timing relationships is essential to make sure that the logic design performs correctly under practical conditions. Timing and delay information are examined.

  11. A Ground-Based 2-Micron DIAL System to Profile Tropospheric CO2 and Aerosol Distributions for Atmospheric Studies

    NASA Technical Reports Server (NTRS)

    Ismail, Syed; Koch, Grady; Abedin, Nurul; Refaat, Tamer; Rubio, Manuel; Davis, Kenneth; Miller, Charles; Singh, Upendra

    2006-01-01

    System will operate at a temperature insensitive CO2 line (2050.967 nm) with side-line tuning and off-set locking. Demonstrated an order of magnitude improvement in laser line locking needed for high precision measurements, side-line operation, and simultaneously double pulsing and line locking. Detector testing of phototransistor has demonstrated sensitivity to aerosol features over long distances in the atmosphere and resolve features approx. 100m. Optical systems that collect light onto small area detectors work well. Receiver optical designs are being optimized and data acquisition systems developed. CO2 line parameter characterization in progress In situ sensor calibration in progress for validation of DIAL CO2 system.

  12. Variations in the Peak Position of the 6.2 micron Interstellar Emission Feature: A Tracer of N in the Interstellar Polycyclic Aromatic Hydrocarbon Population

    NASA Technical Reports Server (NTRS)

    Hudgins, Douglas M.; Bauschlicher, Charles W.; Allamandola, L. J.

    2005-01-01

    This paper presents the results of an investigation of the molecular characteristics that underlie the observed peak position and profile of the nominal 6.2 micron interstellar emission band generally attributed to the CC stretching vibrations of polycyclic aromatic hydrocarbons (PAHs). It begins with a summary of recent experimental and theoretical studies ofthe spectroscopic properties of large (>30 carbon atoms) PAH cations as they relate to this aspect of the astrophysical problem. It then continues with an examination of the spectroscopic properties of a number of PAH variants within the context of the interstellar 6.2 micron emission, beginning with a class of compounds known as polycyclic aromatic nitrogen heterocycles (PANHs; PAHs with one or more nitrogen atoms substituted into their carbon skeleton). In this regard, we summarize the results of recent relevant experimental studies involving a limited set of small PANHs and their cations and then report the results of a comprehensive computational study that extends that work to larger PANH cations including many nitrogen-substituted variants of coronene(+) (C24H12(+)), ovalene(+) (C32H14(+)), circumcoronene(+) (C54H18(+)), and circum-circumcoronene(+) (C96H24(+)). Finally, we report the results of more focused computational studies of selected representatives from a number of other classes of PAH variants that share one or more of the key attributes of the PANH species studied. These alternative classes of PAH variants include (1) oxygen- and silicon-substituted PAH cations; (2) PAH-metal ion complexes (metallocenes) involving the cosmically abundant elements magnesium and iron; and (3) large, asymmetric PAH cations. Overall, the studies reported here demonstrate that increasing PAH size alone is insuEcient to account for the position of the shortest wavelength interstellar 6.2 micron emission bands, as had been suggested by earlier studies. On the other hand, this work reveals that substitution of one or

  13. 47 CFR 101.513 - Transmitter power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Transmitter power. 101.513 Section 101.513 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.513 Transmitter power. The...

  14. 47 CFR 15.212 - Modular transmitters.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... label can use wording such as the following: “Contains Transmitter Module FCC ID: XYZMODEL1” or “Contains FCC ID: XYZMODEL1.” Any similar wording that expresses the same meaning may be used. The Grantee... authorization. (B) If the modular transmitter uses an electronic display of the FCC identification number,...

  15. 47 CFR 15.212 - Modular transmitters.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... label can use wording such as the following: “Contains Transmitter Module FCC ID: XYZMODEL1” or “Contains FCC ID: XYZMODEL1.” Any similar wording that expresses the same meaning may be used. The Grantee... authorization. (B) If the modular transmitter uses an electronic display of the FCC identification number,...

  16. 47 CFR 15.212 - Modular transmitters.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... label can use wording such as the following: “Contains Transmitter Module FCC ID: XYZMODEL1” or “Contains FCC ID: XYZMODEL1.” Any similar wording that expresses the same meaning may be used. The Grantee... authorization. (B) If the modular transmitter uses an electronic display of the FCC identification number,...

  17. 47 CFR 15.212 - Modular transmitters.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... label can use wording such as the following: “Contains Transmitter Module FCC ID: XYZMODEL1” or “Contains FCC ID: XYZMODEL1.” Any similar wording that expresses the same meaning may be used. The Grantee... authorization. (B) If the modular transmitter uses an electronic display of the FCC identification number,...

  18. 47 CFR 15.212 - Modular transmitters.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... label can use wording such as the following: “Contains Transmitter Module FCC ID: XYZMODEL1” or “Contains FCC ID: XYZMODEL1.” Any similar wording that expresses the same meaning may be used. The Grantee... authorization. (B) If the modular transmitter uses an electronic display of the FCC identification number,...

  19. 47 CFR 101.129 - Transmitter location.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Transmitter location. 101.129 Section 101.129 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.129 Transmitter location. (a) The applicant must determine, prior...

  20. 47 CFR 101.129 - Transmitter location.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Transmitter location. 101.129 Section 101.129 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.129 Transmitter location. (a) The applicant must determine, prior...

  1. 47 CFR 101.129 - Transmitter location.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Transmitter location. 101.129 Section 101.129 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.129 Transmitter location. (a) The applicant must determine, prior...

  2. 47 CFR 101.129 - Transmitter location.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Transmitter location. 101.129 Section 101.129 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.129 Transmitter location. (a) The applicant must determine, prior...

  3. 47 CFR 101.129 - Transmitter location.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Transmitter location. 101.129 Section 101.129 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.129 Transmitter location. (a) The applicant must determine, prior...

  4. 47 CFR 90.215 - Transmitter measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Transmitter measurements. 90.215 Section 90.215... MOBILE RADIO SERVICES General Technical Standards § 90.215 Transmitter measurements. (a) The licensee of... may, at the opinion of the licensee, be made by a qualified engineering measurement service, in...

  5. Digital transmitter for data bus communications system

    NASA Technical Reports Server (NTRS)

    Proch, G. E.

    1974-01-01

    Digital transmitter designed for Manchester coded signals (and all signals with ac waveforms) generated at a rate of one megabit per second includes efficient output isolation circuit. Transmitter consists of logic control section, amplifier, and output isolation section. Output isolation circuit provides dynamic impedance at terminals as function of amplifier output level.

  6. 77 FR 1779 - Emergency Locator Transmitters (ELTs)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-11

    ... Federal Aviation Administration Emergency Locator Transmitters (ELTs) AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of intent to cancel Technical Standard Order (TSO)-C91a, Emergency..., Emergency Locator Transmitter (ELT) Equipment. The effect of the cancelled TSO will result in no new...

  7. 47 CFR 90.215 - Transmitter measurements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Transmitter measurements. 90.215 Section 90.215... MOBILE RADIO SERVICES General Technical Standards § 90.215 Transmitter measurements. (a) The licensee of... may, at the opinion of the licensee, be made by a qualified engineering measurement service, in...

  8. 47 CFR 90.215 - Transmitter measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Transmitter measurements. 90.215 Section 90.215... MOBILE RADIO SERVICES General Technical Standards § 90.215 Transmitter measurements. (a) The licensee of... may, at the opinion of the licensee, be made by a qualified engineering measurement service, in...

  9. 47 CFR 90.215 - Transmitter measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Transmitter measurements. 90.215 Section 90.215... MOBILE RADIO SERVICES General Technical Standards § 90.215 Transmitter measurements. (a) The licensee of... may, at the opinion of the licensee, be made by a qualified engineering measurement service, in...

  10. 47 CFR 90.215 - Transmitter measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Transmitter measurements. 90.215 Section 90.215... MOBILE RADIO SERVICES General Technical Standards § 90.215 Transmitter measurements. (a) The licensee of... may, at the opinion of the licensee, be made by a qualified engineering measurement service, in...

  11. 47 CFR 22.1009 - Transmitter locations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Transmitter locations. 22.1009 Section 22.1009 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Offshore Radiotelephone Service § 22.1009 Transmitter locations. The rules in this section establish limitations on the locations...

  12. Assessment of the calibration curve for transmittance pulse-oximetry

    NASA Astrophysics Data System (ADS)

    Doronin, A.; Fine, I.; Meglinski, I.

    2011-11-01

    Optical/laser modalities provide a broad variety of practical solutions for clinical diagnostics and therapy in a range from imaging of single cells and molecules to non-invasive biopsy of specific biological tissues and organs tomography. Near-infrared transmittance pulse oximetry with laser diodes is the accepted standard in current clinical practice and widely used for noninvasive monitoring of oxygen saturation in arterial blood hemoglobin. Conceptual design of practical pulse oximetry systems requires careful selection of various technical parameters, including intensity, wavelength, beam size and profile of incident laser radiation, size, numerical aperture of the detector, as well as a clear understanding of how the spatial and temporal structural alterations in biological tissues can be linked with and can be distinguished by variations of these parameters. In current letter utilizing state-of-the-art NVIDEA CUDA technology, a new object oriented programming paradigm and on-line solutions we introduce a computational tool applied for human finger transmittance spectra simulation and assessment of calibration curve for near-infrared transmitted pulseoximetry.

  13. Compact Ozone Differential Absorption Lidar (DIAL) Transmitter Using Solid-State Dye Polymers

    NASA Technical Reports Server (NTRS)

    Jones, Alton L., Jr.; DeYoung, Russell J.; Elsayid-Ele, Hani

    2001-01-01

    A new potential DIAL laser transmitter is described that uses solid-state dye laser materials to make a simpler, more compact, lower mass laser system. Two solid-state dye laser materials were tested to evaluate their performance in a laser oscillator cavity end pumped by a pulsed Nd:YAG laser at 532 nm. The polymer host polymethyl-methacrylate was injected with a pyrromethene laser dye, PM 580, or PM 597. A narrowband laser oscillator cavity was constructed to produce visible wavelengths of 578 and 600 nm which were frequency doubled into the UV region (299 or 300 nm) by using a BBO crystal, resulting in a maximum energy of 11 mJ at a wavelength of 578 nm when pumped by the Nd:YAG laser at an energy of 100 mJ (532 nm). A maximum output energy of 378 microJ was achieved in the UV region at a wavelength of 289 nm but lasted only 2000 laser shots at a repetition rate of 10 Hz. The results are promising and show that a solid-state dye laser based ozone DIAL system is possible with improvements in the design of the laser transmitter.

  14. An injectable acoustic transmitter for juvenile salmon

    PubMed Central

    Deng, Z. D.; Carlson, T. J.; Li, H.; Xiao, J.; Myjak, M. J.; Lu, J.; Martinez, J. J.; Woodley, C. M.; Weiland, M. A.; Eppard, M. B.

    2015-01-01

    Salmon recovery and the potential detrimental effects of dams on fish have been attracting national attention due to the environmental and economic implications. In recent years acoustic telemetry has been the primary method for studying salmon passage. However, the size of the existing transmitters limits the minimum size of fish that can be studied, introducing a bias to the study results. We developed the first acoustic fish transmitter that can be implanted by injection instead of surgery. The new injectable transmitter lasts four times longer and weighs 30% less than other transmitters. Because the new transmitter costs significantly less to use and may substantially reduce adverse effects of implantation and tag burden, it will allow for study of migration behavior and survival of species and sizes of fish that have never been studied before. The new technology will lead to critical information needed for salmon recovery and the development of fish-friendly hydroelectric systems. PMID:25630763

  15. An injectable acoustic transmitter for juvenile salmon.

    PubMed

    Deng, Z D; Carlson, T J; Li, H; Xiao, J; Myjak, M J; Lu, J; Martinez, J J; Woodley, C M; Weiland, M A; Eppard, M B

    2015-01-01

    Salmon recovery and the potential detrimental effects of dams on fish have been attracting national attention due to the environmental and economic implications. In recent years acoustic telemetry has been the primary method for studying salmon passage. However, the size of the existing transmitters limits the minimum size of fish that can be studied, introducing a bias to the study results. We developed the first acoustic fish transmitter that can be implanted by injection instead of surgery. The new injectable transmitter lasts four times longer and weighs 30% less than other transmitters. Because the new transmitter costs significantly less to use and may substantially reduce adverse effects of implantation and tag burden, it will allow for study of migration behavior and survival of species and sizes of fish that have never been studied before. The new technology will lead to critical information needed for salmon recovery and the development of fish-friendly hydroelectric systems. PMID:25630763

  16. An injectable acoustic transmitter for juvenile salmon

    NASA Astrophysics Data System (ADS)

    Deng, Z. D.; Carlson, T. J.; Li, H.; Xiao, J.; Myjak, M. J.; Lu, J.; Martinez, J. J.; Woodley, C. M.; Weiland, M. A.; Eppard, M. B.

    2015-01-01

    Salmon recovery and the potential detrimental effects of dams on fish have been attracting national attention due to the environmental and economic implications. In recent years acoustic telemetry has been the primary method for studying salmon passage. However, the size of the existing transmitters limits the minimum size of fish that can be studied, introducing a bias to the study results. We developed the first acoustic fish transmitter that can be implanted by injection instead of surgery. The new injectable transmitter lasts four times longer and weighs 30% less than other transmitters. Because the new transmitter costs significantly less to use and may substantially reduce adverse effects of implantation and tag burden, it will allow for study of migration behavior and survival of species and sizes of fish that have never been studied before. The new technology will lead to critical information needed for salmon recovery and the development of fish-friendly hydroelectric systems.

  17. An injectable acoustic transmitter for juvenile salmon.

    PubMed

    Deng, Z D; Carlson, T J; Li, H; Xiao, J; Myjak, M J; Lu, J; Martinez, J J; Woodley, C M; Weiland, M A; Eppard, M B

    2015-01-29

    Salmon recovery and the potential detrimental effects of dams on fish have been attracting national attention due to the environmental and economic implications. In recent years acoustic telemetry has been the primary method for studying salmon passage. However, the size of the existing transmitters limits the minimum size of fish that can be studied, introducing a bias to the study results. We developed the first acoustic fish transmitter that can be implanted by injection instead of surgery. The new injectable transmitter lasts four times longer and weighs 30% less than other transmitters. Because the new transmitter costs significantly less to use and may substantially reduce adverse effects of implantation and tag burden, it will allow for study of migration behavior and survival of species and sizes of fish that have never been studied before. The new technology will lead to critical information needed for salmon recovery and the development of fish-friendly hydroelectric systems.

  18. 47 CFR 90.463 - Transmitter control points.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... remote transmitter or transmitters in the licensee's system of communication, a single pilot lamp or meter may be employed to indicate the activation of both the local and the remote transmitter(s). (2) To... or a pilot lamp or meter which provides a visual indication when the transmitter circuits have...

  19. 47 CFR 90.463 - Transmitter control points.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... remote transmitter or transmitters in the licensee's system of communication, a single pilot lamp or meter may be employed to indicate the activation of both the local and the remote transmitter(s). (2) To... or a pilot lamp or meter which provides a visual indication when the transmitter circuits have...

  20. 47 CFR 90.463 - Transmitter control points.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... remote transmitter or transmitters in the licensee's system of communication, a single pilot lamp or meter may be employed to indicate the activation of both the local and the remote transmitter(s). (2) To... or a pilot lamp or meter which provides a visual indication when the transmitter circuits have...

  1. 47 CFR 90.463 - Transmitter control points.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... remote transmitter or transmitters in the licensee's system of communication, a single pilot lamp or meter may be employed to indicate the activation of both the local and the remote transmitter(s). (2) To... or a pilot lamp or meter which provides a visual indication when the transmitter circuits have...

  2. 47 CFR 90.463 - Transmitter control points.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... remote transmitter or transmitters in the licensee's system of communication, a single pilot lamp or meter may be employed to indicate the activation of both the local and the remote transmitter(s). (2) To... or a pilot lamp or meter which provides a visual indication when the transmitter circuits have...

  3. Transmittance and scattering during wound healing after refractive surgery

    NASA Astrophysics Data System (ADS)

    Mar, Santiago; Martinez-Garcia, C.; Blanco, J. T.; Torres, R. M.; Gonzalez, V. R.; Najera, S.; Rodriguez, G.; Merayo, J. M.

    2004-10-01

    Photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) are frequent techniques performed to correct ametropia. Both methods have been compared in their way of healing but there is not comparison about transmittance and light scattering during this process. Scattering in corneal wound healing is due to three parameters: cellular size and density, and the size of scar. Increase in the scattering angular width implies a decrease the contrast sensitivity. During wound healing keratocytes activation is induced and these cells become into fibroblasts and myofibroblasts. Hens were operated using PRK and LASIK techniques. Animals used in this experiment were euthanized, and immediately their corneas were removed and placed carefully into a cornea camera support. All optical measurements have been done with a scatterometer constructed in our laboratory. Scattering measurements are correlated with the transmittance -- the smaller transmittance is the bigger scattering is. The aim of this work is to provide experimental data of the corneal transparency and scattering, in order to supply data that they allow generate a more complete model of the corneal transparency.

  4. V-band IMPATT transmitter

    NASA Technical Reports Server (NTRS)

    Williams, D.; Ying, R. S.

    1983-01-01

    A V-band transmitter for communication application was developed that has 30 dB gain and consists of six stages of IMPATT amplifiers. The low and medium power stages are stable amplifiers while the two high power stages are triggered oscillators. Hybrid couplers in the form of Magic Tees were used for power combining two single diode IMPATT modules in the high driver stage and for a single diode IMPATT modules at the output stage. Output power of 4 watts CW across a 2.5 GHz band centered at 60 GHz was achieved with an input power of 4 mW. Dynamic range of the amplifier chain is in excess of 7 dB. A single diode one watt stable amplifier over a bandwidth greater than 2.5 GHz, a high power ( 1 watt) stable amplifier capable of operating in either the constant current or constant voltage mode and verification of the advantages of the latter mode of operation; and a 10 channel modulator with built in test equipment (specifically protective circuitry, failure monitoring, and mode of failure indicated) were also developed. The performance requirements of circulators/isolators for reflection amplifiers were also defined and verified.

  5. Ho:YLF Laser Pumped by TM:Fiber Laser

    NASA Astrophysics Data System (ADS)

    Mizutani, Kohei; Ishii, Shoken; Itabe, Toshikazu; Asai, Kazuhiro; Sato, Atsushi

    2016-06-01

    A 2-micron Ho:YLF laser end-pumped by 1.94-micron Tm:fiber laser is described. A ring resonator of 3m length is adopted for the oscillator. The laser is a master oscillator and an amplifier system. It is operated at high repetition rate of 200-5000 Hz in room temperature. The laser outputs were about 9W in CW and more than 6W in Q-switched operation. This laser was developed to be used for wind and CO2 measurements.

  6. Pressure Transmitter Surveillance Using Quaternion Numbers

    NASA Astrophysics Data System (ADS)

    Chicharro, J. M.; García-Berrocal, A.; Balbás, M.; Blazquez, J.

    2002-11-01

    Rosemount pressure transmitters are widely used in Nuclear Power Plants. Mandatory surveillance is focused on the ramp response time, which is calculated using noise analysis techniques. But the response time only accounts for the sensing diaphragm degradation. Considering the other components, a technique for early failure detection is developed. It uses simple properties of the quaternion algebra, mainly the non-commutativity of the multiplication rule. Quaternions are built from the transmitter noise signal. The design of a specific quaternion for a given component is based on an electrical analogy of the transmitter physical model.

  7. Ionospheric very low frequency transmitter

    SciTech Connect

    Kuo, Spencer P.

    2015-02-15

    The theme of this paper is to establish a reliable ionospheric very low frequency (VLF) transmitter, which is also broad band. Two approaches are studied that generate VLF waves in the ionosphere. The first, classic approach employs a ground-based HF heater to directly modulate the high latitude ionospheric, or auroral electrojet. In the classic approach, the intensity-modulated HF heater induces an alternating current in the electrojet, which serves as a virtual antenna to transmit VLF waves. The spatial and temporal variations of the electrojet impact the reliability of the classic approach. The second, beat-wave approach also employs a ground-based HF heater; however, in this approach, the heater operates in a continuous wave mode at two HF frequencies separated by the desired VLF frequency. Theories for both approaches are formulated, calculations performed with numerical model simulations, and the calculations are compared to experimental results. Theory for the classic approach shows that an HF heater wave, intensity-modulated at VLF, modulates the electron temperature dependent electrical conductivity of the ionospheric electrojet, which, in turn, induces an ac electrojet current. Thus, the electrojet becomes a virtual VLF antenna. The numerical results show that the radiation intensity of the modulated electrojet decreases with an increase in VLF radiation frequency. Theory for the beat wave approach shows that the VLF radiation intensity depends upon the HF heater intensity rather than the electrojet strength, and yet this approach can also modulate the electrojet when present. HF heater experiments were conducted for both the intensity modulated and beat wave approaches. VLF radiations were generated and the experimental results confirm the numerical simulations. Theory and experimental results both show that in the absence of the electrojet, VLF radiation from the F-region is generated via the beat wave approach. Additionally, the beat wave approach

  8. The 1.7- to 4.2-micron spectrum of asteroid 1 Ceres - Evidence for structural water in clay minerals

    NASA Technical Reports Server (NTRS)

    Lebofsky, L. A.; Feierberg, M. A.; Larson, H. P.; Johnson, J. R.; Tokunaga, A. T.

    1981-01-01

    A high-resolution Fourier spectrum (1.7-3.5 microns) and medium-resolution spectrophotometry (2.7-4.2 microns) were obtained for Asteroid 1 Ceres. The presence of the 3-micron absorption feature due to water of hydration was confirmed. The 3-micron feature is compared with the 3-micron bands due to water of hydration in clays and salts. It is concluded that the spectrum of Ceres shows a strong absorption at 2.7-2.8 microns due to structural OH groups in clay minerals. The dominant minerals on the surface of Ceres are therefore hydrated clay minerals structurally similar to terrestrial montmorillonites. There is also a narrow absorption feature at 3.1 microns which is attributable to a very small amount of water ice on Ceres. This is the first evidence for ice on the surface of an asteroid.

  9. Compact, Engineered, 2-Micron Coherent Doppler Wind Lidar Prototype for Field and Airborne Validation: Doppler Aerosol WiNd Lidar (DAWN). Interim Review #1 (6 months)

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Singh, Upendra N.; Koch, Grady J.; Yu, Jirong; Amzajerdian, Farzin; Trieu, Bo C.; Petros, Mulugeta

    2006-01-01

    A new project, selected in 2005 by NASA's Science Mission Directorate (SMD), under the Instrument Incubator Program (IIP), will be described. The 3-year effort is intended to design, fabricate, and demonstrate a packaged, rugged, compact, space-qualifiable coherent Doppler wind lidar (DWL) transceiver capable of future validation in an aircraft and/or Unmanned Aerial Vehicle (UAV). The state-of-the-art 2-micron coherent DWL breadboard at NASA/LaRC will be engineered and compactly packaged consistent with future aircraft flights. The packaged transceiver will be integrated into a coherent DWL system test bed at LaRC. Atmospheric wind measurements will be made to validate the packaged technology. This will greatly advance the coherent part of the hybrid DWL solution to the need for global tropospheric wind measurements.

  10. Design, Qualification, and On Orbit Performance of the CALIPSO Aerosol Lidar Transmitter

    NASA Technical Reports Server (NTRS)

    Hovis, Floyd E.; Witt, Greg; Sullivan, Edward T.; Le, Khoa; Weimer, Carl; Applegate, Jeff; Luck, William S., Jr.; Verhapen, Ron; Cisewski, Michael S.

    2007-01-01

    The laser transmitter for the CALIPSO aerosol lidar mission has been operating on orbit as planned since June 2006. This document discusses the optical and laser system design and qualification process that led to this success. Space-qualifiable laser design guidelines included the use of mature laser technologies, the use of alignment sensitive resonator designs, the development and practice of stringent contamination control procedures, the operation of all optical components at appropriately derated levels, and the proper budgeting for the space-qualification of the electronics and software.

  11. Digital transmitter for data bus communications system

    NASA Technical Reports Server (NTRS)

    Proch, G. E. (Inventor)

    1975-01-01

    An improved digital transmitter for transmitting serial pulse code modulation (pcm) data at high bit rates over a transmission line is disclosed. When not transmitting, the transmitter features a high output impedance which prevents the transmitter from loading the transmission line. The pcm input is supplied to a logic control circuit which produces two discrete logic level signals which are supplied to an amplifier. The amplifier, which is transformer coupled to the output isolation circuitry, converts the discrete logic level signals to two high current level, ground isolated signals in the secondary windings of the coupling transformer. The latter signals are employed as inputs to the isolation circuitry which includes two series transistor pairs operating into a hybrid transformer functioning to isolate the transmitter circuitry from the transmission line.

  12. A radio transmitter attachment technique for soras

    USGS Publications Warehouse

    Haramis, G.M.; Kearns, G.D.

    2000-01-01

    We modified a figure-8 leg-loop harness designed for small passerines to attach successfully 1.8-g radio transmitters over the synsacrum of migrant Soras (Porzana carolina). Because of the short caudal region of Soras, addition of a waist loop was critical to securing the transmitter while leg loops were maintained to center the package. Thin gauge (0.6-mm diameter) elastic thread proved ideal for transmitter attachment and allowed for freedom of movement and girth expansion associated with fattening during a 6-10 week stopover. Of 110 Soras radio tagged during three field seasons, only a single mortality was observed and only a single bird lost its transmitter. Migration from the study area was confirmed for 76 (69%) and suspected for another 25 birds (total 92%).

  13. An injectable acoustic transmitter for juvenile salmon

    SciTech Connect

    Deng, Zhiqun; Carlson, Thomas J.; Li, Huidong; Xiao, Jie; Myjak, Mitchell J.; Lu, Jun; Martinez, Jayson J.; Woodley, Christa M.; Weiland, Mark A.; Eppard, Matthew B.

    2015-01-29

    Salmon recovery, and the potential detrimental effects of dams on fish, has been attracting national attention in due to great environmental and economic implications. Acoustic Telemetry has been the primary method for studying salmon passage. However, the size of the existing transmitters limits the minimum size of fish that can be studied, introducing bias to the study results. We developed the first acoustic fish transmitter that can be implanted by injection instead of surgery. The new injectable transmitter offers improved performance and 30% weight reduction. Because the new transmitter costs significantly less to use, substantially reduces adverse effects of implantation, and provides additional biological benefits for tagged fish, it will become the enabling technology for studying migration behavior and survival of species and sizes of fish that have never been studied before. This will lead to critical information for salmon recovery and the development of fish-friendly hydroelectric systems.

  14. An injectable acoustic transmitter for juvenile salmon

    DOE PAGESBeta

    Deng, Zhiqun; Carlson, Thomas J.; Li, Huidong; Xiao, Jie; Myjak, Mitchell J.; Lu, Jun; Martinez, Jayson J.; Woodley, Christa M.; Weiland, Mark A.; Eppard, Matthew B.

    2015-01-29

    Salmon recovery, and the potential detrimental effects of dams on fish, has been attracting national attention in due to great environmental and economic implications. Acoustic Telemetry has been the primary method for studying salmon passage. However, the size of the existing transmitters limits the minimum size of fish that can be studied, introducing bias to the study results. We developed the first acoustic fish transmitter that can be implanted by injection instead of surgery. The new injectable transmitter offers improved performance and 30% weight reduction. Because the new transmitter costs significantly less to use, substantially reduces adverse effects of implantation,more » and provides additional biological benefits for tagged fish, it will become the enabling technology for studying migration behavior and survival of species and sizes of fish that have never been studied before. This will lead to critical information for salmon recovery and the development of fish-friendly hydroelectric systems.« less

  15. Millimeter wave band ultra wideband transmitter MMIC

    NASA Astrophysics Data System (ADS)

    Ling, Jin; Rolland, Nathalie

    2015-09-01

    This paper presents a new millimeter-wave (MMW) ultra wideband (UWB) transmitter MMIC which has been developed in an OMMIC 0.1 μm GaAs PHEMT foundry process (ft = 100 GHz) for 22-29 GHz vehicular radar systems. The transmitter is composed of an MMW negative resistance oscillator (NRO), a power amplifier (PA), and two UWB pulse generators (PGs). In order to convert the UWB pulse signal to MMW frequency and reduce the total power consumption, the MMW NRO is driven by one of the UWB pulse generators and the power amplifier is triggered by another UWB pulse generator. The main advantages of this transmitter are: new design, simple architecture, high-precision distance measurements, infinite ON/OFF switch ratio, and low power consumption. The total power consumption of the transmitter MMIC is 218 mW with a peak output power of 5.5 dBm at 27 GHz.

  16. 47 CFR 73.1665 - Main transmitters.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 25 or 50 kW 50 (c) A licensee may, without further authority or notification to the FCC, replace an... availability of AM broadcast transmitters that are approved or verified for use in the 1605-1705 kHz band, transmitters that are approved or verified for use in the 535-1605 kHz band may be utilized in the 1605-1705...

  17. Compact optical transmitters for CubeSat free-space optical communications

    NASA Astrophysics Data System (ADS)

    Kingsbury, R. W.; Caplan, D. O.; Cahoy, K. L.

    2015-03-01

    We present the results of an architectural trade study and prototype implementation of an optical transmitter suitable for resource-constrained CubeSats. Recent advances in CubeSat attitude determination and control systems have made it possible to achieve three-axis stabilization. This is essential for laser communications systems, which have challenging pointing and stability requirements. Our downlink terminal design fits in a 10 cm x 10 cm x 5 cm volume, uses < 10W of power, weighs < 1 kg, and supports data rates up to 50 Mbps. The terminal incorporates pointing, tracking and acquisition optics, an optical fine-steering mechanism, and a compact transmitter. This work focuses on the development of the transmitter for the Nanosatellite Optical Downlink Experiment (NODE). Two transmitter architectures were considered initially: direct modulation of a high-power laser diode and a master oscillator power amplifier (MOPA). The MOPA-based approach was selected and a prototype "breadboard" was built from commercially available components. The prototype transmitter produces high fidelity (extinction ratio, ER < 33 dB) pulse position modulation (PPM) waveforms at 1550nm with 200mW average output power while consuming 6:5W of electrical power.

  18. Distributed Bragg reflector laser for frequency modulated communication systems

    SciTech Connect

    Chraplyvy, A.R.; Koch, T.L.; Tkach, R.W.

    1990-02-27

    This patent describes a lightwave transmitter. It includes a distributed Bragg reflector laser and means for frequency modulating said laser. The laser comprises first and second semiconductor heterostructure regions.

  19. Estimation of spectral transmittance curves from RGB images in color digital holographic microscopy using speckle illuminations

    NASA Astrophysics Data System (ADS)

    Funamizu, Hideki; Tokuno, Yuta; Aizu, Yoshihisa

    2016-06-01

    We investigate the estimation of spectral transmittance curves in color digital holographic microscopy using speckle illuminations. In color digital holography, it has the disadvantage in that the color-composite image gives poor color information due to the use of lasers with the two or three wavelengths. To overcome this disadvantage, the Wiener estimation method and an averaging process using multiple holograms are applied to color digital holographic microscopy. Estimated spectral transmittance and color-composite images are shown to indicate the usefulness of the proposed method.

  20. Dispersion of 0.5- to 2-micron aerosol in microG and hypergravity as a probe of convective inhomogeneity in the lung

    NASA Technical Reports Server (NTRS)

    Darquenne, C.; West, J. B.; Prisk, G. K.

    1999-01-01

    We used aerosol boluses to study convective gas mixing in the lung of four healthy subjects on the ground (1 G) and during short periods of microgravity (microG) and hypergravity ( approximately 1. 6 G). Boluses of 0.5-, 1-, and 2-micron-diameter particles were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 150 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The dispersion, deposition, and position of the bolus in the expired gas were calculated from these data. For each particle size, both bolus dispersion and deposition increased with Vp and were gravity dependent, with the largest dispersion and deposition occurring for the largest G level. Whereas intrinsic particle motions (diffusion, sedimentation, inertia) did not influence dispersion at shallow depths, we found that sedimentation significantly affected dispersion in the distal part of the lung (Vp >500 ml). For 0.5-micron-diameter particles for which sedimentation velocity is low, the differences between dispersion in microG and 1 G likely reflect the differences in gravitational convective inhomogeneity of ventilation between microG and 1 G.

  1. Effects of external radio transmitters on fish

    SciTech Connect

    Ross, M.J.; McCormick, J.H.

    1981-04-01

    Yellow perch (Perca flavescens) and largemouth bass (Micropterus salmoides) were studied to determine the effects of externally attached radio transmitter tags. Perch that had been tagged with dummy radio tags were more susceptible to predation and more sensitive to environmental stress than were controls. Feeding and respiration rates were similar among dummy tagged and control groups of perch over a 6-week period. The feeding rate of dummy tagged largemouth bass was lower than that of untagged fish over a 3,5-week period. On the basis of these studies, we conclude that weights of external transmitters in water should be less than 1.5% of the fish weight. Design considerations should include streamlining components and an anterior attachment wire at the extreme leading edge of an external transmitter to prevent entanglement of the tag in surrounding vegetation.

  2. Implanting radio transmitters in wintering canvasbacks

    USGS Publications Warehouse

    Olsen, G.H.; Dein, F.J.; Haramis, G.M.; Jorde, D.G.

    1992-01-01

    To conduct telemetry studies of wintering canvasbacks (Aythya valisineria) on Chesapeake Bay [Maryland, USA], we needed to devise a suitable method of radio transmitter attachment. We describe as aseptic, intraabdominal surgical technique, using the inhalation anesthetic isoflurane, to implant 20-g radio transmitters in free-ranging canvasbacks. We evaluated the technique over 3 winters (1987-89), when an annual average of 83 female canvasbacks received implant surgery during a 9-day period in mid-December. Of 253 ducks, 248 (98%) were implanted successfully, and 200 (80.65) completed the 70-day study until early March. No mortality or abnormal behavior from surgery was identified post-release.

  3. Compact multiwavelength transmitter module for multimode fiber optic ribbon cable

    DOEpatents

    Deri, Robert J.; Pocha, Michael D.; Larson, Michael C.; Garrett, Henry E.

    2002-01-01

    A compact multiwavelength transmitter module for multimode fiber optic ribbon cable, which couples light from an M.times.N array of emitters onto N fibers, where the M wavelength may be distributed across two or more vertical-cavity surface-emitting laser (VCSEL) chips, and combining emitters and multiplexer into a compact package that is compatible with placement on a printed circuit board. A key feature is bringing together two emitter arrays fabricated on different substrates--each array designed for a different wavelength--into close physical proximity. Another key feature is to compactly and efficiently combine the light from two or more clusters of optical emitters, each in a different wavelength band, into a fiber ribbon.

  4. High-Efficiency Klystron For Television Transmitters

    NASA Technical Reports Server (NTRS)

    Ramins, Peter; Dayton, James; Mccune, Earl, Sr.; Kosmahl, Henry

    1990-01-01

    Improved klystron designed for use as final amplifier in ultrahigh-frequency (UHF) television transmitter. New device incorporates multistage depressed collector (MSDC) of advanced design to increase efficiency by recovering, from spent electron beam, some of residual kinetic energy otherwise dissipated as heat. Concept applied to increase efficiencies of microwave communication, equipment, radar systems, and particle-beam accelerators.

  5. Fast transmittance model for satellite sounding

    NASA Astrophysics Data System (ADS)

    Rayer, P. J.

    1995-11-01

    Through the use of new line-by-line spectral calculations in both the infrared and microwave regions, coefficients have been generated for the transmittance stage of the fast radiative transfer model used by the United Kingdom Meteorological Office. These permit the fast model to calculate the transmittance for the high-resolution infrared sounder and the microwave sounding unit instruments aboard the National Oceanic and Atmospheric Administration polar-orbiting satellite for a given atmospheric profile, simply by taking these coefficients in linear combination with a set of predictors. These are expressed in terms of the deviation of the profile from a reference. However, the method can be applied to any instrument within the range of the spectral calculations, thereby permitting new coefficients to be calculated as soon as the spectral response details for the instrument become available. It also permits effective consideration to be given in the longer term to new line data or improvements in line-shape theory. The process by which these coefficients have been obtained is described, along with a discussion of some of the tests carried out on their installation into the fast model; these tests show that they are suitable for operational use. The predictors employed by the fast model are discussed, and changes are proposed for those that relate to the water-vapor transmittance. In this respect it was found that the inclusion of predictors that depend primarily on the zenith angle of the radiation path leads to improvements in the transmittance calculation.

  6. Transmittance analysis of diffraction phase grating.

    PubMed

    Jing, Xufeng; Jin, Yunxia

    2011-03-20

    In order to accurately analyze and design the transmittance characteristic of a diffraction phase grating, the validity of both the scalar diffraction theory and the effective medium theory is quantitatively evaluated by the comparison of diffraction efficiencies predicted from both simplified theories to exact results calculated by the rigorous vector electromagnetic theory. The effect of surface profile parameters, including the normalized period, the normalized depth, and the fill factor for the precision of the simplified methods is determined at normal incidence. It is found that, in general, when the normalized period is more than four wavelengths of the incident light, the scalar diffraction theory is useful to estimate the transmittance of the phase grating. When the fill factor approaches 0.5, the error of the scalar method is minimized, and the scalar theory is accurate even at the grating period of two wavelengths. The transmittance characteristic as a function of the normalized period is strongly influenced by the grating duty cycle, but the diffraction performance on the normalized depth is independent of the fill factor of the grating. Additionally, the effective medium theory is accurate for evaluating the diffraction efficiency within an error of less than around 1% when no higher-order diffraction waves appear and only the zero-order waves exist. The precision of the effective medium theory for calculating transmittance properties as a function of the normalized period, the normalized groove depth, and the polarization state of incident light is insensitive to the fill factor of the phase grating. PMID:21460923

  7. Transmittal Letters: Communicating the Financial Picture.

    ERIC Educational Resources Information Center

    Piotrowski, Craig L.

    1987-01-01

    The transmittal letter, part of a school district's comprehensive annual financial report, provides a creative opportunity to communicate the financial picture of a district to readers. After the introduction, the letter should include sections on (1) mission, services, and environment; (2) financial highlights; (3) systems and controls; and (4)…

  8. New laser materials for laser diode pumping

    NASA Technical Reports Server (NTRS)

    Jenssen, H. P.

    1990-01-01

    The potential advantages of laser diode pumped solid state lasers are many with high overall efficiency being the most important. In order to realize these advantages, the solid state laser material needs to be optimized for diode laser pumping and for the particular application. In the case of the Nd laser, materials with a longer upper level radiative lifetime are desirable. This is because the laser diode is fundamentally a cw source, and to obtain high energy storage, a long integration time is necessary. Fluoride crystals are investigated as host materials for the Nd laser and also for IR laser transitions in other rare earths, such as the 2 micron Ho laser and the 3 micron Er laser. The approach is to investigate both known crystals, such as BaY2F8, as well as new crystals such as NaYF8. Emphasis is on the growth and spectroscopy of BaY2F8. These two efforts are parallel efforts. The growth effort is aimed at establishing conditions for obtaining large, high quality boules for laser samples. This requires numerous experimental growth runs; however, from these runs, samples suitable for spectroscopy become available.

  9. Light transmittance of fiber posts following various surface treatments: A preliminary study

    PubMed Central

    Cekic-Nagas, Isil; Ergun, Gulfem; Egilmez, Ferhan

    2016-01-01

    Objective: The objective of this study was to compare the light transmittance of fiber posts following application of various surface treatments. Materials and Methods: Fiber post specimens (Snowpost red size #14) were tested (n = 7). The fiber posts were divided into five groups according to the application of surface treatments: Group 1: No surface treatment; Group 2: Etched with hydrofluoric acid (HF) + silane application; Group 3: Airborne-particle abraded with 110 μm Al2O3; Group 4: Irradiated with erbium: Yttrium-aluminum-garnet laser; Group 5: Airborne-particle abraded with 110 μm Al2O3 + silane application. The light transmittance of the specimens was compared using a spectrophotometer. Statistical significance was determined using one-way analysis of variance (ANOVA) (α = 0.05). Results: One-way ANOVA revealed that surface treatment had significant effects on light transmittance of posts (P < 0.001). While laser treatment had the highest percentage of light transmittance, treatment with silane following HF application had the lowest. Conclusion: Application of surface treatments might negatively affect the light transmission property of fiber posts. PMID:27095902

  10. Frequency agile OPO-based transmitters for multiwavelength DIAL

    SciTech Connect

    Velsko, S.P.; Ruggiero, A.; Herman, M.

    1996-09-01

    We describe a first generation mid-infrared transmitter with pulse to pulse frequency agility and both wide and narrow band capability. This transmitter was used to make multicomponent Differential Absorption LIDAR (DIAL) measurements in the field.

  11. Frequency agile OPO-based transmitters for multiwavelength DIAL

    SciTech Connect

    Velsko, S.P.; Ruggiero, A.; Herman, M.

    1996-09-01

    We describe a first generation mid-infrared transmitter with pulse-to- pulse frequency agility and both wide and narrow band capability. This transmitter was used to make multicomponent DIAL measurements in the field.

  12. Interior, looking north at transmitter and power supply areas ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior, looking north at transmitter and power supply areas - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector One Transmitter Building, At the end of Steam Road, Moscow, Somerset County, ME

  13. Oblique view to the south of the Transmitter Building ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oblique view to the south of the Transmitter Building - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Transmitter Building, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  14. Method to determine and adjust the alignment of the transmitter and receiver fields of view of a LIDAR system

    DOEpatents

    Schmitt, Randal L.; Henson, Tammy D.; Krumel, Leslie J.; Hargis, Jr., Philip J.

    2006-06-20

    A method to determine the alignment of the transmitter and receiver fields of view of a light detection and ranging (LIDAR) system. This method can be employed to determine the far-field intensity distribution of the transmitter beam, as well as the variations in transmitted laser beam pointing as a function of time, temperature, or other environmental variables that may affect the co-alignment of the LIDAR system components. In order to achieve proper alignment of the transmitter and receiver optical systems when a LIDAR system is being used in the field, this method employs a laser-beam-position-sensing detector as an integral part of the receiver optics of the LIDAR system.

  15. Solid state Ku-band spacecraft transmitters

    NASA Technical Reports Server (NTRS)

    Wisseman, W. R.; Tserng, H. Q.; Coleman, D. J.; Doerbeck, F. H.

    1977-01-01

    A transmitter is considered that consists of GaAs IMPATT and Read diodes operating in a microstrip circuit environment to provide amplification with a minimum of 63 db small signal gain and a minimum compressed gain at 5 W output of 57 db. Reported are Schottky-Read diode design and fabrication, microstrip and circulator optimization, preamplifier development, power amplifier development, dc-to-dc converter design, and integration of the breadboard transmitter modules. A four-stage power amplifier in cascade with a three-stage preamplifier had an overall gain of 56.5 db at 13.5 GHz with a power output of 4.5 W. A single-stage Read amplifier delivered 5.9 W with 4 db gain at 22% efficiency.

  16. Electronic transmittance phase extracted from mesoscopic interferometers

    PubMed Central

    2012-01-01

    The usual experimental set-up for measuring the wave function phase shift of electrons tunneling through a quantum dot (QD) embedded in a ring (i.e., the transmittance phase) is the so-called ‘open’ interferometer as first proposed by Schuster et al. in 1997, in which the electrons back-scattered at source and the drain contacts are absorbed by additional leads in order to exclude multiple interference. While in this case one can conveniently use a simple two-path interference formula to extract the QD transmittance phase, the open interferometer has also a number of draw-backs, such as a reduced signal and some uncertainty regarding the effects of the extra leads. Here we present a meaningful theoretical study of the QD transmittance phase in ‘closed’ interferometers (i.e., connected only to source and drain leads). By putting together data from existing literature and giving some new proofs, we show both analytically and by numerical simulations that the existence of phase lapses between consecutive resonances of the ‘bare’ QD is related to the signs of the corresponding Fano parameters - of the QD + ring system. More precisely, if the Fano parameters have the same sign, the transmittance phase of the QD exhibits a Π lapse. Therefore, closed mesoscopic interferometers can be used to address the ‘universal phase lapse’ problem. Moreover, the data from already existing Fano interference experiments from Kobayashi et al. in 2003 can be used to infer the phase lapses. PMID:23061877

  17. 47 CFR 101.131 - Transmitter construction and installation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... appropriately labeled pilot lamp or meter which will provide continuous visual indication at the transmitter... independently of any remote control circuits associated therewith. (d) At each transmitter control point the... indication when the transmitter is radiating, or, in lieu thereof, a pilot lamp or meter which will...

  18. 47 CFR 101.131 - Transmitter construction and installation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... appropriately labeled pilot lamp or meter which will provide continuous visual indication at the transmitter... independently of any remote control circuits associated therewith. (d) At each transmitter control point the... indication when the transmitter is radiating, or, in lieu thereof, a pilot lamp or meter which will...

  19. 47 CFR 101.131 - Transmitter construction and installation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... appropriately labeled pilot lamp or meter which will provide continuous visual indication at the transmitter... independently of any remote control circuits associated therewith. (d) At each transmitter control point the... indication when the transmitter is radiating, or, in lieu thereof, a pilot lamp or meter which will...

  20. 47 CFR 101.131 - Transmitter construction and installation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... appropriately labeled pilot lamp or meter which will provide continuous visual indication at the transmitter... independently of any remote control circuits associated therewith. (d) At each transmitter control point the... indication when the transmitter is radiating, or, in lieu thereof, a pilot lamp or meter which will...

  1. 47 CFR 101.131 - Transmitter construction and installation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... appropriately labeled pilot lamp or meter which will provide continuous visual indication at the transmitter... independently of any remote control circuits associated therewith. (d) At each transmitter control point the... indication when the transmitter is radiating, or, in lieu thereof, a pilot lamp or meter which will...

  2. Pocket-sized tone-modulated FM transmitter

    NASA Technical Reports Server (NTRS)

    Couvillon, L. A.

    1969-01-01

    Pressure of a button on a crystal-controlled transmitter causes generation of a tone. The tone modulates the FM transmitter which in turn radiates by way of the enclosed loop antenna, through the radio-frequency-transparent wall of the transmitters case to the receiver.

  3. 47 CFR 22.507 - Number of transmitters per station.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... may include remote, stand-alone transmitters under the single system-wide authorization, if the remote, stand-alone transmitter is linked to the system via a control/repeater facility or by satellite. Including a remote, stand-alone transmitter in a system-wide authorization does not alter the...

  4. 21 CFR 870.2920 - Telephone electrocardiograph transmitter and receiver.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Telephone electrocardiograph transmitter and... § 870.2920 Telephone electrocardiograph transmitter and receiver. (a) Identification. A telephone electrocardiograph transmitter and receiver is a device used to condition an electrocardiograph signal so that it...

  5. 21 CFR 870.2920 - Telephone electrocardiograph transmitter and receiver.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Telephone electrocardiograph transmitter and... § 870.2920 Telephone electrocardiograph transmitter and receiver. (a) Identification. A telephone electrocardiograph transmitter and receiver is a device used to condition an electrocardiograph signal so that it...

  6. 21 CFR 870.2920 - Telephone electrocardiograph transmitter and receiver.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Telephone electrocardiograph transmitter and... § 870.2920 Telephone electrocardiograph transmitter and receiver. (a) Identification. A telephone electrocardiograph transmitter and receiver is a device used to condition an electrocardiograph signal so that it...

  7. 21 CFR 870.2920 - Telephone electrocardiograph transmitter and receiver.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Telephone electrocardiograph transmitter and... § 870.2920 Telephone electrocardiograph transmitter and receiver. (a) Identification. A telephone electrocardiograph transmitter and receiver is a device used to condition an electrocardiograph signal so that it...

  8. 14 CFR 91.207 - Emergency locator transmitters.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) There is attached to the airplane an approved automatic type emergency locator transmitter that is in... approved automatic type emergency locator transmitter that is in operable condition, except that after June... the event of crash impact is minimized. Fixed and deployable automatic type transmitters must...

  9. 47 CFR 97.313 - Transmitter power standards.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Transmitter power standards. 97.313 Section 97... AMATEUR RADIO SERVICE Technical Standards § 97.313 Transmitter power standards. (a) An amateur station must use the minimum transmitter power necessary to carry out the desired communications. (b)...

  10. 47 CFR 97.313 - Transmitter power standards.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Transmitter power standards. 97.313 Section 97... AMATEUR RADIO SERVICE Technical Standards § 97.313 Transmitter power standards. (a) An amateur station must use the minimum transmitter power necessary to carry out the desired communications. (b)...

  11. 47 CFR 97.313 - Transmitter power standards.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Transmitter power standards. 97.313 Section 97... AMATEUR RADIO SERVICE Technical Standards § 97.313 Transmitter power standards. (a) An amateur station must use the minimum transmitter power necessary to carry out the desired communications. (b)...

  12. 47 CFR 97.313 - Transmitter power standards.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Transmitter power standards. 97.313 Section 97... AMATEUR RADIO SERVICE Technical Standards § 97.313 Transmitter power standards. (a) An amateur station must use the minimum transmitter power necessary to carry out the desired communications. (b)...

  13. 47 CFR 97.313 - Transmitter power standards.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Transmitter power standards. 97.313 Section 97... AMATEUR RADIO SERVICE Technical Standards § 97.313 Transmitter power standards. (a) An amateur station must use the minimum transmitter power necessary to carry out the desired communications. (b)...

  14. 47 CFR 80.209 - Transmitter frequency tolerances.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Transmitter frequency tolerances. 80.209... SERVICES STATIONS IN THE MARITIME SERVICES General Technical Standards § 80.209 Transmitter frequency tolerances. (a) The frequency tolerance requirements applicable to transmitters in the maritime services...

  15. 47 CFR 95.639 - Maximum transmitter power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Maximum transmitter power. 95.639 Section 95.639 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Technical Regulations Technical Standards § 95.639 Maximum transmitter power. (a) No GMRS transmitter, under any condition...

  16. 21 CFR 870.2920 - Telephone electrocardiograph transmitter and receiver.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Telephone electrocardiograph transmitter and... § 870.2920 Telephone electrocardiograph transmitter and receiver. (a) Identification. A telephone electrocardiograph transmitter and receiver is a device used to condition an electrocardiograph signal so that it...

  17. Acoustic Transmitters for Underwater Neutrino Telescopes

    PubMed Central

    Ardid, Miguel; Martínez-Mora, Juan A.; Bou-Cabo, Manuel; Larosa, Giuseppina; Adrián-Martínez, Silvia; Llorens, Carlos D.

    2012-01-01

    In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to achieve the proposed aim. The developed compact array has practical features such as easy manageability and operation. The prototype designs and the results of different tests are described. The techniques applied for these two acoustic systems are so powerful and versatile that may be of interest in other marine applications using acoustic transmitters. PMID:22666022

  18. Solid state transmitters for spaceborne radars

    NASA Technical Reports Server (NTRS)

    Turlington, T. R.

    1983-01-01

    The SEASAT-A synthetic aperture radar, the first spaceborne SAR, utilized an all solid state RF signal synthesizer and L-band transmitter to drive a corporately fed flat plate array. The RF signal synthesizer generated a linear FM ""CHIRP'' waveform and provided stable CW reference signals used to upconvert the received signal to a unified S-band downlink channel, and to synchronize satellite control logic. The transmitter generated 1200 watts peak RF power (66 watts average) at a center frequency of 1.275 GHz from 354 watts of DC prime power. Linear FM CHIRP swept symmetrically around the center frequency with a bandwidth of 19.05 MHz and a pulse duration of 33.8 sec. Pulse repetition rate was variable from 1647 to 1944 pps. These transmitter signal parameters combined with the flat plate 34 x 7.5 ft aperture at an orbital altitude of 498 miles and a look angle 20 deg off nadir gave the SAR an 85 foot resolution over a 15.5 mile wide swath.

  19. Acoustic transmitters for underwater neutrino telescopes.

    PubMed

    Ardid, Miguel; Martínez-Mora, Juan A; Bou-Cabo, Manuel; Larosa, Giuseppina; Adrián-Martínez, Silvia; Llorens, Carlos D

    2012-01-01

    In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to achieve the proposed aim. The developed compact array has practical features such as easy manageability and operation. The prototype designs and the results of different tests are described. The techniques applied for these two acoustic systems are so powerful and versatile that may be of interest in other marine applications using acoustic transmitters.

  20. [Lasers].

    PubMed

    Passeron, T

    2012-11-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients.

  1. Lasers.

    PubMed

    Passeron, T

    2012-12-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients.

  2. Laser rocket system analysis

    NASA Technical Reports Server (NTRS)

    Jones, W. S.; Forsyth, J. B.; Skratt, J. P.

    1979-01-01

    The laser rocket systems investigated in this study were for orbital transportation using space-based, ground-based and airborne laser transmitters. The propulsion unit of these systems utilizes a continuous wave (CW) laser beam focused into a thrust chamber which initiates a plasma in the hydrogen propellant, thus heating the propellant and providing thrust through a suitably designed nozzle and expansion skirt. The specific impulse is limited only by the ability to adequately cool the thruster and the amount of laser energy entering the engine. The results of the study showed that, with advanced technology, laser rocket systems with either a space- or ground-based laser transmitter could reduce the national budget allocated to space transportation by 10 to 345 billion dollars over a 10-year life cycle when compared to advanced chemical propulsion systems (LO2-LH2) of equal capability. The variation in savings depends upon the projected mission model.

  3. Measurement method for light transmittance of layered metamaterials.

    PubMed

    Isozaki, Akihiro; Kan, Tetsuo; Ajiki, Yoshiharu; Matsumoto, Kiyoshi; Shimoyama, Isao

    2013-06-01

    We propose a method to measure light transmittance of layered metamaterials by placing the metamaterials directly on a Si photodiode. Our measurement method enables the direct detection of transmitted light that appears as an evanescent wave in natural materials. Here, we report the transmittance measurements of a typical metamaterial using this method. The metamaterial was composed of Ag/Al(2)O(3) layers and was fabricated by direct evaporation on the Si photodiode. The measured transmittance agrees with the simulated transmittance. Our results confirmed that this measurement method can determine the transmittance properties of metamaterials and that it is applicable to other types of metamaterials.

  4. Transmitter microdischarges in communications and broadcast Satellites

    NASA Astrophysics Data System (ADS)

    Briskman, Robert D.; Kaliski, Michael A. R.

    2016-09-01

    Most commercial communications and broadcast satellites operating at microwave radio frequencies use traveling wave tube amplifiers (TWTAs) as high power transmitters. Since TWTAs work at high voltages, it is not uncommon to experience micro-discharges, especially early in life. This observation led to the introduction of an autonomous restart function in the companion high voltage power supply (the electronic power conditioner or EPC) of the TWTA as a safety feature. A microdischarge with enough energy above a threshold would lead to a momentary removal of high voltages, followed by an automatic restart, which is usually sufficient to allow the microdischarge event to clear with minimal loss of RF transmission. In most cases the energy involved in the microdischarge is low enough that the removal of high voltages is not required and the event may go undetected. However, an unusual signature was first noted in early 1997 on a Ku-band satellite transmitter, where the characteristics of the microdischarge event were such that the control anode voltage dropped below nominal and typically recovered over a 20 min period. Such microdischarge events became known as the "20 min Effect" which has since been observed over subsequent years on other Ku-band TWTAs, as well as on Ka-band and S-band satellite TWTA transmitters in numerous satellites. This paper summarizes the in-orbit data on such microdischarges as well as the believed cause. In addition, the paper includes results from three S-band TWTAs which have operated on life test for many years. Due to ease of their monitoring instrumentation as contrast to monitoring microdischarges on orbiting operational satellites via telemetry, new data have been accumulated on this effect. The data substantiate the previous findings that microdischarges do not significantly affect satellite operation or their transmissions nor diminish the TWTAs performance, including long lifetime.

  5. Advances in High Energy Solid-State Pulsed 2-micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

    NASA Astrophysics Data System (ADS)

    Singh, Upendra; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael; Remus, Ruben

    2015-04-01

    NASA Langley Research Center has a long history of developing 2 µm lasers. From fundamental spectroscopy research, theoretical prediction of new materials, laser demonstration and engineering of lidar systems, it has been a very successful program spanning around two decades. Successful development of 2 µm lasers has led to development of a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement with an unprecedented laser pulse energy of 250-mJ in a rugged package. This high pulse energy is produced by a Ho:Tm:LuLiF laser with an optical amplifier. While the lidar is meant for use as an airborne instrument, ground-based tests were carried out to characterize performance of the lidar. Atmospheric measurements will be presented, showing the lidar's capability for wind measurement in the atmospheric boundary layer and free troposphere. Lidar wind measurements are compared to a balloon sonde, showing good agreement between the two sensors. Similar architecture has been used to develop a high energy, Ho:Tm:YLF double-pulsed 2 μm Integrated Differential Absorption Lidar (IPDA) instrument based on direct detection technique that provides atmospheric column CO2 measurements. This instrument has been successfully used to measure atmospheric CO2 column density initially from a ground mobile lidar trailer, and then it was integrated on B-200 plane and 20 hrs of flight measurement were made from an altitude ranging 1500 meter to 8000 meter. These measurements were compared to in-situ measurements and NOAA airborne flask measurement to derive the dry mixing ratio of the column CO2 by reflecting the signal by various reflecting surfaces such as land, vegetation, ocean surface, snow and sand. The lidar measurements when compared showed a very agreement with in-situ and airborne flask measurement. NASA Langley Research Center is currently developing a triple-pulsed 2 μm Integrated Differential Absorption Lidar (IPDA

  6. An efficient magnetron transmitter for superconducting accelerators

    DOE PAGESBeta

    Kazakevich, G.; Lebedev, V.; Yakovlev, V.; Pavlov, V.

    2016-09-22

    A concept of a highly-efficient high-power magnetron transmitter allowing wide-band phase and the mid-frequency power control at the frequency of the locking signal is proposed. The proposal is aimed for powering Superconducting RF (SRF) cavities of intensity-frontier accelerators. The transmitter is intended to operate with phase and amplitude control feedback loops allowing suppression of microphonics and beam loading in the SRF cavities. The concept utilizes injectionlocked magnetrons controlled in phase by the locking signal supplied by a feedback system. The injection-locking signal pre-excites the magnetron and allows its operation below the critical voltage. This realizes control of the magnetron powermore » in a wide range by control of the magnetron current. Pre-excitation of the magnetron by the locking signal provides an output power range up to 10 dB. Experimental studies were carried out with 2.45 GHz, 1 kW, CW magnetrons. They demonstrated stable operation of the magnetrons and power control at a low noise level. In conclusion, an analysis of the kinetics of the drifting charge in the drift approximation substantiates the concept and the experimental results.« less

  7. Behavior of sandhill cranes harnessed with different satellite transmitters

    USGS Publications Warehouse

    Olsen, G.H.; Ellis, D.H.; Landfried, S.E.; Miller, L.H.; Klugman, S.S.; Fuller, M.R.; Vermillion, C.H.

    1992-01-01

    The effectiveness of various attachment methods and designs of platform transmitting terminals (PTT's) was tested on captive sandhill cranes (Grus canadensis) at the Patuxent Wildlife Research Center, Laurel, Maryland, during 1989-91. Combinations of attachment and transmitter designs included neoprene cord harness with batteries separate from the transmitter (2 harness designs), Teflon ribbon harness with batteries incorporated into the transmitter package (4 transmitter models), and a package attached directly to the bird with epoxy glue only. Physical effects seen on cranes wearing PTT's ranged from skin lacerations (caused by rubbing of harness material) to no observed effects (other than feather wear). The most successful harness material and design utilized a Teflon ribbon harness with the 4 ribbon ends from the transmitter forming a neck loop and a body loop joined at the sternum. Time spent by sandhill cranes performing most activities did not change after transmitter attachment using this harness method.

  8. Improving Reliability of High Power Quasi-CW Laser Diode Arrays for Pumping Solid State Lasers

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Baggott, Renee S.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.

    2005-01-01

    Most Lidar applications rely on moderate to high power solid state lasers to generate the required transmitted pulses. However, the reliability of solid state lasers, which can operate autonomously over long periods, is constrained by their laser diode pump arrays. Thermal cycling of the active regions is considered the primary reason for rapid degradation of the quasi-CW high power laser diode arrays, and the excessive temperature rise is the leading suspect in premature failure. The thermal issues of laser diode arrays are even more drastic for 2-micron solid state lasers which require considerably longer pump pulses compared to the more commonly used pump arrays for 1-micron lasers. This paper describes several advanced packaging techniques being employed for more efficient heat removal from the active regions of the laser diode bars. Experimental results for several high power laser diode array devices will be reported and their performance when operated at long pulsewidths of about 1msec will be described.

  9. HO:LULF and HO:LULF Laser Materials

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P. (Inventor); Morrison, Clyde A. (Inventor); Filer, Elizabeth D. (Inventor); Jani, Mahendra G. (Inventor); Murray, Keith E. (Inventor); Lockard, George E. (Inventor)

    1998-01-01

    A laser host material LULF (LuLiF4) is doped with holmium (Ho) and thulium (Tm) to produce a new laser material that is capable of laser light production in the vicinity of 2 microns. The material provides an advantage in efficiency over conventional Ho lasers because the LULF host material allows for decreased threshold and upconversion over such hosts as YAG and YLF. The addition of Tm allows for pumping by commonly available GaAlAs laser diodes. For use with flashlamp pumping, erbium (Er) may be added as an additional dopant. For further upconversion reduction, the Tm can be eliminated and the Ho can be directly pumped.

  10. 13. View of southerly side of transmitter building no. 101 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. View of southerly side of transmitter building no. 101 from south, showing tracking radar (tr) on top of transmitter building no. 102 in background left and abandoned radome on top of transmitter building no. 101 in middle of photograph with utilidor passageway link to right of photograph. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  11. Transmittance Variations Analysis in Sunglasses Lenses Post Sun Exposure

    NASA Astrophysics Data System (ADS)

    Loureiro, A. D.; Gomes, L. M.; Ventura, L.

    2016-07-01

    The hypothesis that sunglass ultraviolet (UV) protection can degrade with Sun exposure has never been proven experimentally. No sunglasses standards take into account UV transmittance changes after long Sun exposure. We selected 12 sunglass lenses and measured transmittance values from 280 nm to 780 nm. After 50 hours of exposure, new transmittance measurements were taken and transmittance variations inferior to 0.2% were observed. The exposition continues longer and more lenses will be tested to obtain conclusive results. We hope to obtain experimental data to confirm UV protection loss hypothesis and obtain a relation between Sun and solar simulator exposition

  12. Multichip transmitter/receiver module for fiber optical sensors

    NASA Astrophysics Data System (ADS)

    Waegli, Peter; Morel, Philippe

    1997-09-01

    Amongst the various sensing principles studied for use in optical fiber sensors, color coding has proven to be successful in commercial applications. Color coded sensors are based on commercially available and easy to handle components (i.e. LED's, lasers, multimode fibers) and the same basic optoelectronics can be used for a wide variety of applications. Such applications are: the remote measurement of chemical composition (pH, hydrogen, oxygen, aromatic hydrocarbons, humidity etc.), biochemical reactions and physical parameters (e.g. temperature, pressure, etc.) in medical applications (e.g. blood gas analysis, immunosensors, etc.), environmental monitoring, process control and on the factory floor. A versatile transmitter/receiver-module, which can be easily customized, has been developed as a multi chip module (MCM). This MCM can be directly mounted onto the printed circuit board, is small in size (50 X 50 X 12 mm3) and contains all optical, optoelectronic and electronic components and circuits to interface optically with the sensors and electrically with the microprocessor and its associated circuitry used for data analysis. Up to four sensors can be connected to one module and individually interrogated under software control. The design and the characteristics of the MCM as well as its application in possible sensor arrangements will be discussed with special emphasis on its use in a four channel fiber optic temperature sensor.

  13. Waveguide Heterodyne Mixers at THz-Frequencies - Superconducting Hot Electron Bolometers on 2-micron Si3N4 Membranes for GREAT and CONDOR

    NASA Astrophysics Data System (ADS)

    Munoz, Pedro Pablo

    2007-04-01

    realized in this thesis by fabricating the mixer device on a thin (i.e. 2 micron) membrane layer deposited on a bulk silicon carrier wafer. The membrane is released by backside etching of the wafer after device fabrication. A large supporting frame is needed around the device for handling and contacting. A possible approach is to fabricate the frame and the mixer simultaneously on one wafer. In the process presented here the membrane-HEB devices and the supporting frames are fabricated separately avoiding the loss of wafer "real estate" for the support frames and thus allowing for up to 690 devices to be simultaneously produced on a single 30 mm square wafer. Fabricating many identical devices for arrays is possible even if many devices are damaged during fabrication. Further it is possible to test many different parameter-variations on one single wafer. The price to pay is a slightly more involved assembly procedure, which has been realized for the first time for 1.4 and 1.9 THz in this thesis. The fabrication of the phonon-cooled HEBs was fully realized at the KOSMA clean room facilities. The sputter deposition of ultra-thin NbTiN films with critical temperatures as high as 8.5 K is one of the technological highlights, already described at [1]. This thesis focused on the optimization of the contact interfaces between the electrodes and the ultrathin superconducting layer. Etching the interface previous to deposition of the electrodes leads to a better control over the interface. The effect of the etching parameters on the HEBs has been investigated. To restore the superconducting film properties that might be affected by the cleaning process, a NbTiN layer (20 nm) is deposited on top of the contact area. The additional superconducting layer between the bolometer thin film and the heat sinks has a positive effect on the mixer performance but introduced complications in the fabrication process which have been solved in this thesis. The fabricated waveguide HEB mixers on

  14. Atmospheric transmittance model for photosynthetically active radiation

    SciTech Connect

    Paulescu, Marius; Stefu, Nicoleta; Gravila, Paul; Paulescu, Eugenia; Boata, Remus; Pacurar, Angel; Mares, Oana; Pop, Nicolina; Calinoiu, Delia

    2013-11-13

    A parametric model of the atmospheric transmittance in the PAR band is presented. The model can be straightforwardly applied for calculating the beam, diffuse and global components of the PAR solar irradiance. The required inputs are: air pressure, ozone, water vapor and nitrogen dioxide column content, Ångström's turbidity coefficient and single scattering albedo. Comparison with other models and ground measured data shows a reasonable level of accuracy for this model, making it suitable for practical applications. From the computational point of view the calculus is condensed into simple algebra which is a noticeable advantage. For users interested in speed-intensive computation of the effective PAR solar irradiance, a PC program based on the parametric equations along with a user guide are available online at http://solar.physics.uvt.ro/srms.

  15. Marine Mammal Transmitter for porpoise tracking

    NASA Astrophysics Data System (ADS)

    Briscoe, W. G.

    The Marine Mammal Transmitter (MMT) forms part of the equipment to be used in a worldwide Porpoise Tracking System. Knowledge of porpoise migration, distribution characteristics, and population estimates are needed to aid in protection of the porpoise. A major problem is suffocation of porpoises when they are caught in tuna purse seine fishing nets. Location of the porpoise can be determined to within + or - 5 kilometers. The MMT utilizes low power CMOS integrated circuits in timing and control circuits to extend battery life. The MMT with battery pack is contained in two cylinders which are two inches in diameter and 8.5 inches long. The unit is mounted to the porpoise's dorsal fin with a vertical quarter wave monopole antenna extending from one of the cylinders. A signal from the MMT is transmitted to the Nimbus satellite. From there the information is later transmitted to a ground receiver and a data processing facility.

  16. Laser-SPS systems analysis and environmental impact assessment

    NASA Technical Reports Server (NTRS)

    Beverly, R. E., III

    1980-01-01

    The systems feasibility and environmental impact of replacing the microwave transmitters on the Satellite Power System with laser transmitters are examined. The lasers suggested are two molecular-gas electric-discharge lasers (EDL's), namely the CO and CO2 lasers. Calculations are made on system efficiency, atmospheric transmission efficiency, and laser beam spreading. It is found that the present satellite concept using lasers is far too inefficient and massive to be economically viable. However, the safety issues associated with laser power transmission appear tractable, and no effects could be identified which present a real danger of serious injury to the environment, although certain phenomena deserve closer scrutiny.

  17. A study of atmospheric optical scattering parameters at 1.5 and 2 micron region for solid state Doppler lidar applications

    NASA Technical Reports Server (NTRS)

    Margalit, Eli; Amzajerdian, Farzin; Benoist, Rodney; Dubinsky, Richard

    1992-01-01

    The increasing interest in the development of an eye-safe, solid state, Doppler lidar for avionic applications has created the need for a quantitative evaluation of atmospheric effects on performance. Theoretical calculations were completed for optical scattering parameters to be compared with the field measurements. Computer codes were developed for the required calculations and designed to be interactive and user friendly in order to support comparison with experimental results and, thus, provide the basis for evaluation of eye-safe Doppler lidar over a wide range of atmospheric conditions and geographical locations. A holmium Doppler lidar operating at 2.09 microns was constructed for atmospheric backscattering, attenuation, and wind velocity measurements. Theoretical calculations and field studies were performed for backscatter coefficients. The selected wavelengths correspond to Er:glass, Tm:YAG, and Tm,Ho:YAG solid state lasers that are suitable for use in an eye-safe Doppler lidar system.

  18. 47 CFR 80.63 - Maintenance of transmitter power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... transmitter power during its operation. Station Requirements—Land Stations ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Maintenance of transmitter power. 80.63 Section... SERVICES STATIONS IN THE MARITIME SERVICES Operating Requirements and Procedures Station...

  19. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... is 25 kHz. Channel No. Center frequency (MHz) 1 216.0125 2 216.0375 3 216.0625 4 216.0875 5 216.1125... 216.9875 (2) LPRS transmitters operating on standard band channels must be maintained within a....975 (2) LPRS transmitters operating on extra band channels must be maintained within a...

  20. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... is 25 kHz. Channel No. Center frequency (MHz) 1 216.0125 2 216.0375 3 216.0625 4 216.0875 5 216.1125... 216.9875 (2) LPRS transmitters operating on standard band channels must be maintained within a....975 (2) LPRS transmitters operating on extra band channels must be maintained within a...

  1. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... is 25 kHz. Channel No. Center frequency (MHz) 1 216.0125 2 216.0375 3 216.0625 4 216.0875 5 216.1125... 216.9875 (2) LPRS transmitters operating on standard band channels must be maintained within a....975 (2) LPRS transmitters operating on extra band channels must be maintained within a...

  2. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... is 25 kHz. Channel No. Center frequency (MHz) 1 216.0125 2 216.0375 3 216.0625 4 216.0875 5 216.1125... 216.9875 (2) LPRS transmitters operating on standard band channels must be maintained within a....975 (2) LPRS transmitters operating on extra band channels must be maintained within a...

  3. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... is 25 kHz. Channel No. Center frequency (MHz) 1 216.0125 2 216.0375 3 216.0625 4 216.0875 5 216.1125... 216.9875 (2) LPRS transmitters operating on standard band channels must be maintained within a....975 (2) LPRS transmitters operating on extra band channels must be maintained within a...

  4. 47 CFR 95.628 - MedRadio transmitters.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false MedRadio transmitters. 95.628 Section 95.628 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Technical Regulations Technical Standards § 95.628 MedRadio transmitters. (a) Frequency...

  5. Juvenile Salmon Acoustic Telemetry System Transmitter Downsize Assessment

    SciTech Connect

    Carlson, Thomas J.; Myjak, Mitchell J.

    2010-04-30

    At the request of the U.S. Army Corps of Engineers, Portland District, researchers from Pacific Northwest National Laboratory investigated the use of an application-specific integrated circuit (ASIC) to reduce the weight and volume of Juvenile Salmon Acoustic Telemetry System (JSATS) transmitters while retaining current functionality. Review of the design of current JSATS transmitters identified components that could be replaced by an ASIC while retaining the function of the current transmitter and offering opportunities to extend function if desired. ASIC design alternatives were identified that could meet transmitter weight and volume targets of 200 mg and 100 mm3. If alternatives to the cylindrical batteries used in current JSATS transmitters can be identified, it could be possible to implant ASIC-based JSATS transmitters by injection rather than surgery. Using criteria for the size of fish suitable for surgical implantation of current JSATS transmitters, it was concluded that fish as small as 70 mm in length could be implanted with an ASIC-based transmitter, particularly if implantation by injection became feasible.

  6. 47 CFR 73.685 - Transmitter location and antenna system.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Transmitter location and antenna system. 73.685... RADIO BROADCAST SERVICES Television Broadcast Stations § 73.685 Transmitter location and antenna system... and antenna height above average terrain employed, the following minimum field strength in dB...

  7. 47 CFR 73.685 - Transmitter location and antenna system.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Transmitter location and antenna system. 73.685... RADIO BROADCAST SERVICES Television Broadcast Stations § 73.685 Transmitter location and antenna system... and antenna height above average terrain employed, the following minimum field strength in dB...

  8. 47 CFR 73.685 - Transmitter location and antenna system.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Transmitter location and antenna system. 73.685... RADIO BROADCAST SERVICES Television Broadcast Stations § 73.685 Transmitter location and antenna system... and antenna height above average terrain employed, the following minimum field strength in dB...

  9. 47 CFR 73.685 - Transmitter location and antenna system.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Transmitter location and antenna system. 73.685... RADIO BROADCAST SERVICES Television Broadcast Stations § 73.685 Transmitter location and antenna system... and antenna height above average terrain employed, the following minimum field strength in dB...

  10. 47 CFR 5.107 - Transmitter control requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Transmitter control requirements. 5.107 Section 5.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EXPERIMENTAL RADIO SERVICE Technical Standards and Operating Requirements § 5.107 Transmitter control requirements. Each licensee shall be responsible for maintaining control of...

  11. 47 CFR 5.107 - Transmitter control requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Transmitter control requirements. 5.107 Section 5.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EXPERIMENTAL RADIO SERVICE (OTHER THAN BROADCAST) Technical Standards and Operating Requirements § 5.107 Transmitter control...

  12. 47 CFR 5.107 - Transmitter control requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Transmitter control requirements. 5.107 Section 5.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EXPERIMENTAL RADIO SERVICE (OTHER THAN BROADCAST) Technical Standards and Operating Requirements § 5.107 Transmitter control...

  13. 47 CFR 74.18 - Transmitter control and operation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Transmitter control and operation. 74.18... EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES General; Rules Applicable to All Services in Part 74 § 74.18 Transmitter control and operation. Except where...

  14. 47 CFR 5.107 - Transmitter control requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Transmitter control requirements. 5.107 Section 5.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EXPERIMENTAL RADIO SERVICE (OTHER THAN BROADCAST) Technical Standards and Operating Requirements § 5.107 Transmitter control...

  15. 47 CFR 74.18 - Transmitter control and operation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Transmitter control and operation. 74.18... EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES General; Rules Applicable to All Services in Part 74 § 74.18 Transmitter control and operation. Except where...

  16. 47 CFR 74.18 - Transmitter control and operation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Transmitter control and operation. 74.18... EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES General; Rules Applicable to All Services in Part 74 § 74.18 Transmitter control and operation. Except where...

  17. 47 CFR 5.107 - Transmitter control requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Transmitter control requirements. 5.107 Section 5.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EXPERIMENTAL RADIO SERVICE Technical Standards and Operating Requirements § 5.107 Transmitter control requirements. Each licensee...

  18. 47 CFR 74.18 - Transmitter control and operation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Transmitter control and operation. 74.18... EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES General; Rules Applicable to All Services in Part 74 § 74.18 Transmitter control and operation. Except where...

  19. 47 CFR 80.203 - Authorization of transmitters for licensing.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... VHF transmitters may employ external or internal devices to send synthesized voice transmissions for... synthesized voice message must be certificated as an integral unit. (3) The synthesized voice distress... transmitter to be used to send and receive standard voice communications. (5) Use of the microphone must...

  20. 47 CFR 80.203 - Authorization of transmitters for licensing.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... this chapter. Transmitters of a model authorized before October 1, 1986 will be considered type... (iv) Copying of a channel selection program directly from another transmitter (cloning) using devices... application a working unit of the type for which certification is desired. Manufacturers of radar...

  1. 47 CFR 80.203 - Authorization of transmitters for licensing.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... this chapter. Transmitters of a model authorized before October 1, 1986 will be considered type... (iv) Copying of a channel selection program directly from another transmitter (cloning) using devices... application a working unit of the type for which certification is desired. Manufacturers of radar...

  2. 29 CFR 1921.15 - Transmittal of record.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Transmittal of record. 1921.15 Section 1921.15 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... WORKERS' COMPENSATION ACT Decision and Order § 1921.15 Transmittal of record. Immediately following...

  3. 43 CFR 4.702 - Transmittal of appeal file.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Transmittal of appeal file. 4.702 Section... PROCEDURES Special Rules Applicable to Other Appeals and Hearings § 4.702 Transmittal of appeal file. Within... decision is being appealed shall transmit to the Office of the Director the entire official file in...

  4. Efficacy of using radio transmitters to monitor least tern chicks

    USGS Publications Warehouse

    Whittier, Joanna B.; Leslie, David M.

    2005-01-01

    Little is known about Least Tern (Sterna antillarum) chicks from the time they leave the nest until fledging because they are highly mobile and cryptically colored. We evaluated the efficacy of using radiotelemetry to monitor Interior Least Tern (S. a. athalassos) chicks at Salt Plains National Wildlife Refuge, Oklahoma. In 1999, we attached radio transmitters to 26 Least Tern chicks and tracked them for 2-17 days. No adults abandoned their chicks after transmitters were attached. Transmitters did not appear to alter growth rates of transmittered chicks (P = 0.36) or prevent feather growth, although dermal irritation was observed on one chick. However, without frequent reattachment, transmitters generally did not remain on chicks <1 week old for more than 2 days because of feather growth and transmitter removal, presumably by adult terns. Although the presence of transmitters did not adversely affect Least Tern chicks, future assessments should investigate nonintrusive methods to improve retention of transmitters on young chicks and reduce the number of times that chicks need to be handled.

  5. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false FM transmitter site map submissions. 73.4108... RADIO BROADCAST SERVICES Rules Applicable to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and Public Notice, adopted October 24, 1986. 1 FCC Rcd 381...

  6. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false FM transmitter site map submissions. 73.4108... RADIO BROADCAST SERVICES Rules Applicable to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and Public Notice, adopted October 24, 1986. 1 FCC Rcd 381...

  7. 47 CFR 22.165 - Additional transmitters for existing systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... contours of the additional transmitter(s) must be totally encompassed by the composite interfering contour... “service area” and “interfering contours” must be determined using the same method as for stations in the Paging and Radiotelephone Service. The service area and interfering contours so determined for...

  8. 47 CFR 22.165 - Additional transmitters for existing systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... contours of the additional transmitter(s) must be totally encompassed by the composite interfering contour... Radiotelephone Service. A “service area” and “interfering contours” must be determined using the same method as for stations in the Paging and Radiotelephone Service. The service area and interfering contours...

  9. 47 CFR 22.165 - Additional transmitters for existing systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... contours of the additional transmitter(s) must be totally encompassed by the composite interfering contour... “service area” and “interfering contours” must be determined using the same method as for stations in the Paging and Radiotelephone Service. The service area and interfering contours so determined for...

  10. 47 CFR 22.165 - Additional transmitters for existing systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... contours of the additional transmitter(s) must be totally encompassed by the composite interfering contour... Radiotelephone Service. A “service area” and “interfering contours” must be determined using the same method as for stations in the Paging and Radiotelephone Service. The service area and interfering contours...

  11. 47 CFR 22.165 - Additional transmitters for existing systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... contours of the additional transmitter(s) must be totally encompassed by the composite interfering contour... Radiotelephone Service. A “service area” and “interfering contours” must be determined using the same method as for stations in the Paging and Radiotelephone Service. The service area and interfering contours...

  12. 47 CFR 22.377 - Certification of transmitters.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... MOBILE SERVICES Operational and Technical Requirements Technical Requirements § 22.377 Certification of transmitters. Except as provided in paragraph (b) of this section, transmitters used in the Public Mobile... authorization (see subpart D of this part) do not have to be certificated....

  13. 47 CFR 22.377 - Certification of transmitters.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... MOBILE SERVICES Operational and Technical Requirements Technical Requirements § 22.377 Certification of transmitters. Except as provided in paragraph (b) of this section, transmitters used in the Public Mobile... authorization (see subpart D of this part) do not have to be certificated....

  14. 10 CFR 455.152 - Transmittal of record on review.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 3 2011-01-01 2011-01-01 false Transmittal of record on review. 455.152 Section 455.152 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION GRANT PROGRAMS FOR SCHOOLS AND HOSPITALS AND BUILDINGS... Transmittal of record on review. On or before 15 days from receipt of a notice requesting...

  15. Interior view to the east, note the row of transmitters ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view to the east, note the row of transmitters and the cables in the foreground - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Transmitter Building, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  16. 47 CFR 80.209 - Transmitter frequency tolerances.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Transmitter frequency tolerances. 80.209 Section 80.209 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES General Technical Standards § 80.209 Transmitter frequency tolerances. (a) The frequency...

  17. 47 CFR 95.628 - MedRadio transmitters.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false MedRadio transmitters. 95.628 Section 95.628 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Technical Regulations Technical Standards § 95.628 MedRadio transmitters. (a) Frequency...

  18. High-power transmitter automation. [deep space network

    NASA Technical Reports Server (NTRS)

    Gosline, R.

    1980-01-01

    The current status of the transmitter automation development applicable to all transmitters in the deep space network is described. Interface and software designs are described that improve reliability and reduce the time required for subsystem turn-on and klystron saturation to less than 10 minutes.

  19. 30. View of mezzanine floor level in transmitter building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. View of mezzanine floor level in transmitter building no. 102 showing control transmitter electronic cabinets and control modules. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  20. Contaminant Monitor Laser

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Under a Small Business Innovation Research contract from Langley Research Center, OPOTEK, Inc. developed a laser transmitter for remote sensing of water vapor in the upper atmosphere. As a leader in developing and using Differential Absorption Lidar, a remote sensing technique to monitor ozone and water vapor in the atmosphere, NASA was interested in upgrading the capabilities of its airborn laser systems. The laser transmitter developed for NASA was used for measuring water vapor in the infrared region. By broadening this concept to other wavelengths, OPOTEK believes a range of industrial applications can be met. In addition, the tunable laser system can be used by the Drug Enforcement Administration to discern the by-products from illegal drug manufacturing. A host of other government, university, and industrial laboratory uses for the technology are also being examined as follow-up by the company.

  1. Solar radio-transmitters on snail kites in Florida

    USGS Publications Warehouse

    Snyder, N.F.R.; Beissinger, S.R.; Fuller, M.R.

    1989-01-01

    The effectiveness and safety of one- and two-stage solar radio-transmitters in tracking the movements and survival of adult and fledgling Snail Kites (Rostrhamus sociabilis) were evaluated between 1979 and 1983 in southern Florida. Transmitters were attached to birds with back-pack arrangements using teflon ribbon straps. Accessory plastic shields minimized feather coverage of the solar cells. Intact transmitters were seen on birds up to 47 mo after installation. Operating lives ranged from 8 to 21 mo for one-stage, and 10 to 14 mo for two-stage transmitters. Because survival of adult and nestling radio-marked kites was high, we conclude that our transmitter-attachment method had little effect on the birds.

  2. 47 CFR 90.473 - Operation of internal transmitter control systems through licensed fixed control points.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Operation of internal transmitter control... Transmitter Control Internal Transmitter Control Systems § 90.473 Operation of internal transmitter control systems through licensed fixed control points. An internal transmitter control system may be...

  3. Flexible, reconfigurable, power efficient transmitter and method

    NASA Technical Reports Server (NTRS)

    Bishop, James W. (Inventor); Zaki, Nazrul H. Mohd (Inventor); Newman, David Childress (Inventor); Bundick, Steven N. (Inventor)

    2011-01-01

    A flexible, reconfigurable, power efficient transmitter device and method is provided. In one embodiment, the method includes receiving outbound data and determining a mode of operation. When operating in a first mode the method may include modulation mapping the outbound data according a modulation scheme to provide first modulation mapped digital data, converting the first modulation mapped digital data to an analog signal that comprises an intermediate frequency (IF) analog signal, upconverting the IF analog signal to produce a first modulated radio frequency (RF) signal based on a local oscillator signal, amplifying the first RF modulated signal to produce a first RF output signal, and outputting the first RF output signal via an isolator. In a second mode of operation method may include modulation mapping the outbound data according a modulation scheme to provide second modulation mapped digital data, converting the second modulation mapped digital data to a first digital baseband signal, conditioning the first digital baseband signal to provide a first analog baseband signal, modulating one or more carriers with the first analog baseband signal to produce a second modulated RF signal based on a local oscillator signal, amplifying the second RF modulated signal to produce a second RF output signal, and outputting the second RF output signal via the isolator. The digital baseband signal may comprise an in-phase (I) digital baseband signal and a quadrature (Q) baseband signal.

  4. MST radar transmitter control and monitor system

    NASA Technical Reports Server (NTRS)

    Brosnahan, J. W.

    1983-01-01

    A generalized transmitter control and monitor card was developed using the Intel 8031 (8051 family) microprocessor. The design was generalized so that this card can be utilized for virtually any control application with only firmware changes. The block diagram appears in Figure 2. The card provides for local control using a 16 key keypad (up to 64 keys are supported). The local display is four digits of 7 segment LEDs. The display can indicate the status of all major system parameters and provide voltage readout for the analog signal inputs. The card can be populated with only the chips required for a given application. Fully populated, the card has two RS-232 serial ports for computer communications. It has a total of 48 TTL parallel lines that can define as either inputs or outputs in groups of four. A total of 32 analog inputs with a 0-5 volt range are supported. In addition, a real-time clock/calendar is available if required. A total of 16 k bytes of ROM and 16 k bytes of RAM is available for programming. This card can be the basis of virtually any monitor or control system with appropriate software.

  5. Fusion pore regulation of transmitter release.

    PubMed

    Fernández-Peruchena, Carlos; Navas, Sergio; Montes, María A; Alvarez de Toledo, Guillermo

    2005-09-01

    During the last decade a wealth of new information about the properties of the exocytotic fusion pore is changing our current view of exocytosis. The exocytotic fusion pore, a necessary stage before the full merging of the vesicle membrane with the plasma membrane, is becoming a key cellular structure that might critically control the amount of neurotransmitter released into the synaptic cleft and that can be subjected to control by second messengers and phosphorylated proteins. Fusion pores form, expand to fully merge membranes, or can close leaving an intact and identical synaptic vesicle in place for a new round of exocytosis. Transient formation of fusion pores is the mechanistic representation of the "kiss-and-run" hypothesis of transmitter release and offers new alternatives for synaptic vesicle recycling besides to the classical mechanism mediated by clathrin coat endocytosis. For vesicle recycling transient fusion pores ensures a fast mechanism for maintaining an active pool of synaptic vesicles. The size reached by transient fusion pores and the time spent on the open state can determine the release of subquantal synaptic transmission, which could be a mechanism of synaptic potentiation. In this review we will described the electrophysiological and fluorescence methods that contribute to further explore the biophysical properties of the exocytotic fusion pore and the relevant experiments obtained by these methods.

  6. Radiation Exposure Monitoring and Information Transmittal System.

    2005-06-23

    Version 01 The Radiation Exposure Monitoring and Information Transmittal (REMIT) system is designed to assist U.S. Nuclear Regulatory Commission (NRC) licensees in meeting the reporting requirements of the Revised 10 CFR Parts 20.1001 through 20.2401 as outlined in Regulatory Guide 8.7, Rev.1, Instructions for Recording and Reporting Occupational Exposure Data. REMIT is a PC‑based menu driven system that facilitates the manipulation of data base files to record and report radiation exposure information. REMIT is designedmore » to be user‑friendly and contains the full text of Regulatory Guide 8.7, Rev.1, on‑line as well as context‑sensitive help throughout the program. The user can enter data directly from NRC Forms 4 or 5. REMIT allows the user to view the individual's exposure in relation to regulatory or administrative limits and will alert the user to exposures in excess of these limits. The system also provides for the calculation and summation of dose from intakes and the determination of the dose to the maximally exposed extremity for the monitoring year. REMIT can produce NRC Forms 4 and 5 in paper and electronic format and can import/export data from ASCII and data base files. Additional information is available from the web page www.reirs.com.« less

  7. Evaluation of 3 radio transmitters and collar designs for Amazona

    USGS Publications Warehouse

    Meyers, J.M.

    1996-01-01

    I evaluated 3 radio transmitter attachments and designs for adult parrots. Two of the transmitters and attachments were similar to those used previously in the study on fledgling and adult parrots. I designed, in collaboration with the manufacturer, a third transmitter and attachment that provided protection of key areas from chewing and eventual destruction of the attachment or transmitter. This design was used successfully to radio-track parrots an average of 43.4 weeks (range = 35.9-51.6 weeks). It was the only transmitter of the 3 tested to operate without failure (>36 weeks) caused by chewing damage to the transmitter, antenna, collar, or attachment mechanism (Fisher's exact test, 3 df, P = 0.0003). Its adjustable collar, made from 59 kg-test stainless steel wire covered with plastic heat-shrink tubing, was sturdy and easy to apply. Transmitters for parrots should be enclosed in a protective metal case (brass) and have metal crimped tubes (brass or copper) protecting key areas, such as the base of the antenna and mechanism for attachment of the collar.

  8. Piezoelectric transducer design for a miniaturized injectable acoustic transmitter

    NASA Astrophysics Data System (ADS)

    Li, H.; Jung, K. W.; Deng, Z. D.

    2015-11-01

    Implantable acoustic transmitters have been used in the last 20 years to track fish movement for fish survival and migration behavior studies. However, the relatively large weights and sizes of commercial transmitters limit the populations of studied fish. The surgical implantation procedures may also affect fish adversely and incur a significant amount of labor. Therefore, a smaller, lighter, and injectable transmitter was needed, and similar or better acoustic performance and service life over those provided by existing commercial transmitters was desired. To develop such a small transmitter, a number of technical challenges, including design optimization of the piezoelectric transducer, needed to be overcome. Our efforts to optimize the transducer focused on improving the average source level in the 180° range in which the signal was not blocked by the transmitter body. We found that a novel off-center tube transducer improved the average source level by 1.5 dB. An acoustic reflector attached to the back of the transducer also improved the source level by 1.3 dB. We found that too small a gap between the transducer and the component placed behind it resulted in distortion of the beam pattern. Lastly, a tuning inductor in series with the transducer was used to help optimize the source level. The findings and techniques developed in this work contributed to the successful development and implementation of a new injectable transmitter.

  9. Multibeam Laser Altimeter for Planetary Topographic Mapping

    NASA Technical Reports Server (NTRS)

    Garvin, J. B.; Bufton, J. L.; Harding, D. J.

    1993-01-01

    Laser altimetry provides an active, high-resolution, high-accuracy method for measurement of planetary and asteroid surface topography. The basis of the measurement is the timing of the roundtrip propagation of short-duration pulses of laser radiation between a spacecraft and the surface. Vertical, or elevation, resolution of the altimetry measurement is determined primarily by laser pulse width, surface-induced spreading in time of the reflected pulse, and the timing precision of the altimeter electronics. With conventional gain-switched pulses from solid-state lasers and nanosecond resolution timing electronics, submeter vertical range resolution is possible anywhere from orbital altitudes of approximately 1 km to altitudes of several hundred kilometers. Horizontal resolution is a function of laser beam footprint size at the surface and the spacing between successive laser pulses. Laser divergence angle and altimeter platform height above the surface determine the laser footprint size at the surface, while laser pulse repetition rate, laser transmitter beam configuration, and altimeter platform velocity determine the spacing between successive laser pulses. Multiple laser transmitters in a single laser altimeter instrument that is orbiting above a planetary or asteroid surface could provide across-track as well as along-track coverage that can be used to construct a range image (i.e., topographic map) of the surface. We are developing a pushbroom laser altimeter instrument concept that utilizes a linear array of laser transmitters to provide contiguous across-track and along-track data. The laser technology is based on the emerging monolithic combination of individual, 1-sq cm diode-pumped Nd:YAG laser pulse emitters. Details of the multi-emitter laser transmitter technology, the instrument configuration, and performance calculations for a realistic Discovery-class mission will be presented.

  10. Space Operation of the MOLA Laser

    NASA Technical Reports Server (NTRS)

    Afzal, Robert S.

    2000-01-01

    Interest in lasers for space applications such as active remote sensing in Earth orbit, planetary science, and inter-satellite laser communications is growing. These instruments typically use diode-pumped solid state lasers for the laser transmitter. The mission specifications and constraints of space qualification, place strict requirements on the design and operation of the laser. Although a laser can be built in the laboratory to meet performance specifications relatively routinely, tile mission constraints demand unique options and compromises in the materials used, and design to ensure the success of the mission. Presently, the best laser architecture for a light weight, rugged, high peak power and efficient transmitter is a diode laser pumped ND:YAG laser. Diode lasers can often obviate the need for water cooling, reduce the size and weight of the laser, increase the electrical to optical efficiency, system reliability, and lifetime. This paper describes the in-space operation and performance of the Mars Orbiter Laser Altimeter (MOLA) laser transmitter, representing the current state-of-the-art in space-based solid- state lasers.

  11. Investigation of bidirectional reflectance and transmittance of rough silicon wafers

    NASA Astrophysics Data System (ADS)

    Shen, Yu-Jiun

    2002-01-01

    This research seeks to perform accurate measurements of bidirectional reflectance and transmittance of rough silicon wafers by a new benchtop scatterometer. An empirical model was developed according to the measurement data. The results will contribute to the application of radiative heat transfer modeling for a rapid thermal processing (RTP) system. In an RTP system, the radiation environment can greatly affect the reading of a lightpipe radiation thermometer. Knowledge of the bidirectional reflectance of rough silicon wafers is needed for the prediction of the reflected radiation into the radiometer, so that it can be used for accurate temperature measurement. The new scatterometer is capable of measuring out-of-plane scattering distribution at wavelengths of 635, 785, and 1550 nm from a diode laser system. Results were analyzed and compared to standard measurements at the National Institute of Standards and Technology. The relative difference is within the level of 5% for wavelengths of 635 and 785 nm and 10% for 1550 nm. An empirical model in the simple form of a two-parameter exponential function was proposed to fit the measured data. The results show that this approach can represent the measured data better than some other theoretical models discussed in this thesis. The empirical model can be used to estimate conical reflectance around a specular direction for different collecting half-cone angles. That provides a quick way to compare specular peak measurements from different instruments with varied collecting resolution. An in situ measurement in the mock-up RTP chamber was also performed. Results demonstrated the feasibility of compact optics setup, which mainly uses fiber-coupled devices.

  12. Single frequency and wavelength stabilized near infrared laser source for water vapor DIAL remote sensing application

    NASA Astrophysics Data System (ADS)

    Chuang, Ti; Walters, Brooke; Shuman, Tim; Losee, Andrew; Schum, Tom; Puffenberger, Kent; Burnham, Ralph

    2015-02-01

    Fibertek has demonstrated a single frequency, wavelength stabilized near infrared laser transmitter for NASA airborne water vapor DIAL application. The application required a single-frequency laser transmitter operating at 935 nm near infrared (NIR) region of the water vapor absorption spectrum, capable of being wavelength seeded and locked to a reference laser source and being tuned at least 100 pm across the water absorption spectrum for DIAL on/off measurements. Fibertek is building a laser transmitter system based on the demonstrated results. The laser system will be deployed in a high altitude aircraft (ER-2 or UAV) to autonomously perform remote, long duration and high altitude water vapor measurements.

  13. Transmitter antenna placement in indoor environments using particle swarm optimisation

    NASA Astrophysics Data System (ADS)

    Talepour, Zeinab; Tavakoli, Saeed; Ahmadi-Shokouh, Javad

    2013-07-01

    The aim of this article is to suitably locate the minimum number of transmitter antennas in a given indoor environment to achieve good propagation coverage. To calculate the electromagnetic field in various points of the environment, we develop a software engine, named ray-tracing engine (RTE), in Matlab. To achieve realistic calculations, all parameters of geometry and material of building are considered. Particle swarm optimisation is employed to determine good location of transmitters. Simulation results show that a full coverage is obtained through suitably locating three transmitters.

  14. Leaf bidirectional reflectance and transmittance in corn and soybean

    NASA Technical Reports Server (NTRS)

    Walter-Shea, E. A.; Norman, J. M.; Blad, B. L.

    1989-01-01

    Bidirectional optical properties of leaves must be adequately characterized to develop comprehensive and reliably predictive canopy radiative-transfer models. Directional reflectance and transmittance factors of individual corn and soybean leaves were measured at source incidence angles (SIAs) 20, 45, and 70 deg and numerous view angles in the visible and NIR. Bidirectional reflectance distributions changed with increasing SIA, with forward scattering most pronounced at 70 deg. Directional-hemispherical reflectance generally increased and transmittance decreased with increased SIA. Directional-hemispherical reflectance factors were higher and transmittances were lower than the nadir-viewed reflectance component.

  15. 47 CFR 95.639 - Maximum transmitter power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... citations affecting § 95.639, see the List of CFR Sections Affected, which appears in the Finding Aids... (ERP). (e) The maximum transmitter output power authorized for LPRS stations is 100 mW. (f) In the...

  16. 47 CFR 95.855 - Transmitter effective radiated power limitation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Transmitter effective radiated power limitation. The effective radiated power (ERP) of each CTS and RTU shall... with an ERP exceeding 20 watts. No mobile RTU may transmit with an ERP exceeding 4 watts....

  17. Surgical insertions of transmitters and telemetry methods in fisheries research

    USGS Publications Warehouse

    Wargo Rub, A. Michelle; Jepsen, Niels; Liedtke, Theresa L.; Moser, L; Weber III, E. P. Scott

    2015-01-01

    Use of electronic transmitter and monitoring systems to track movements of aquatic animals has increased continuously since the inception of these systems in the mid-1950s. The purpose of the present report is to provide information about veterinary principles and their incorporation into surgical implantation procedures for fish. We also intend to provide insight into the unique challenges of field-based aquatic surgical studies. Within this context, 4 aspects of the process for surgical implantation of transmitters in fish (ie, handling, aseptic technique, anesthesia, and implantation) will be described. Effects of surgical insertion of transmitters (ie, tagging) and aspects of the surgical implantation process where collaboration and professional exchanges among nonveterinarian researchers and veterinarians may be most fruitful will be discussed. Although this report focuses on surgical implantation, the principles and protocols described here (other than incision and suture placement) are also applicable to studies that involve injection of transmitters into fish.

  18. 65. VIEW OF RADAR TRANSMITTER AREA, LOOKING NORTH Everett Weinreb, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    65. VIEW OF RADAR TRANSMITTER AREA, LOOKING NORTH Everett Weinreb, photographer, March 1988 - Mount Gleason Nike Missile Site, Angeles National Forest, South of Soledad Canyon, Sylmar, Los Angeles County, CA

  19. Simultaneous occupational exposure to FM and UHF transmitters.

    PubMed

    Valič, Blaž; Kos, Bor; Gajšek, Peter

    2012-01-01

    Occupational exposure caused by large broadcasting transmitters exceeds current reference levels. As it is common for different radio and TV transmitters to share the location, we analysed combined exposure on a 40-m high mast. The frequency modulation (FM) transmitter, located between the 10th and 30th metre, had the power of 25 kW, whereas an ultra-high frequency (UHF) transmitter of 5 kW occupied the top 8 m of the mast. Measured and calculated values of the electric field strength exceeded the reference levels up to 10 times; however, the results for the specific absorption rate (SAR) values show that the reference levels are very conservative for FM exposure, i.e., basic restrictions are not exceeded even when the reference levels are exceeded 10 times. However, for UHF exposure the reference levels are not conservative; they give a good prediction of real exposure.

  20. Emergency Locator Transmitter (ELT) batteries guidance and recommendations

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Batteries for use with Emergency locator transmitters are discussed. Types of batteries, real-time activation considerations, encapsulation of cells in a battery pack, cold storage to extend shelf life, and general requirements are among the topics covered.

  1. Thermoregulatory effects of radiotelemetry transmitters on mallard ducklings

    USGS Publications Warehouse

    Bakken, G.S.; Reynolds, P.S.; Kenow, K.P.; Korschgen, C.E.; Boysen, A.F.

    1996-01-01

    Many telemetry transmitter attachments disrupt downy insulation, and may bias survival studies during cold weather by making ducklings more susceptible to chilling. We compared thermal responses of untreated 1-day-old mallards (Anas platyrhynchos) to ducklings carrying external sutured backpack or subcutaneously implanted transmitters. Ducklings carrying external transmitters showed areas of increased surface temperature in thermographic images. However, open-circuit respirometry studies at 5, 10, 15, 20, and 25 C and wind speeds of 0.1, 0.2, 0.5, and 1 m/s indicated no biologically significant differences in total heat production, net heat production, or short-term body mass loss. These results do not exclude the possibility of other negative effects of transmitters on duckling behavior and survival.

  2. Aircraft-mounted crash-activated transmitter device

    NASA Technical Reports Server (NTRS)

    Manoli, R.; Ulrich, B. R. (Inventor)

    1976-01-01

    An aircraft crash location transmitter tuned to transmit on standard emergency frequencies is reported that is shock mounted in a sealed circular case atop the tail of an aircraft by means of a shear pin designed to fail under a G loading associated with a crash situation. The antenna for the transmitter is a metallic spring blade coiled like a spiral spring around the outside of the circular case. A battery within the case for powering the transmitter is kept trickle charged from the electrical system of the aircraft through a break away connector on the case. When a crash occurs, the resultant ejection of the case from the tail due to a failure of the shear pin releases the free end of the antenna which automatically uncoils. The accompanying separation of the connector effects closing of the transmitter key and results in commencement of transmission.

  3. Simultaneous occupational exposure to FM and UHF transmitters.

    PubMed

    Valič, Blaž; Kos, Bor; Gajšek, Peter

    2012-01-01

    Occupational exposure caused by large broadcasting transmitters exceeds current reference levels. As it is common for different radio and TV transmitters to share the location, we analysed combined exposure on a 40-m high mast. The frequency modulation (FM) transmitter, located between the 10th and 30th metre, had the power of 25 kW, whereas an ultra-high frequency (UHF) transmitter of 5 kW occupied the top 8 m of the mast. Measured and calculated values of the electric field strength exceeded the reference levels up to 10 times; however, the results for the specific absorption rate (SAR) values show that the reference levels are very conservative for FM exposure, i.e., basic restrictions are not exceeded even when the reference levels are exceeded 10 times. However, for UHF exposure the reference levels are not conservative; they give a good prediction of real exposure. PMID:22721535

  4. 48 CFR 805.207 - Preparation and transmittal of synopses.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Actions 805.207 Preparation and transmittal of synopses. (a) When an A/E evaluation board is ready to advertise for A/E services, the board must establish the geographic area within which it will consider...

  5. 48 CFR 805.207 - Preparation and transmittal of synopses.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Actions 805.207 Preparation and transmittal of synopses. (a) When an A/E evaluation board is ready to advertise for A/E services, the board must establish the geographic area within which it will consider...

  6. 48 CFR 805.207 - Preparation and transmittal of synopses.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Actions 805.207 Preparation and transmittal of synopses. (a) When an A/E evaluation board is ready to advertise for A/E services, the board must establish the geographic area within which it will consider...

  7. 48 CFR 805.207 - Preparation and transmittal of synopses.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Actions 805.207 Preparation and transmittal of synopses. (a) When an A/E evaluation board is ready to advertise for A/E services, the board must establish the geographic area within which it will consider...

  8. 1. VIEW TO NORTHWEST WITH RADIO CONTROL HOUSE (RIGHT), TRANSMITTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. VIEW TO NORTHWEST WITH RADIO CONTROL HOUSE (RIGHT), TRANSMITTER TOWER (CENTER), AND NORTH BREAKWATER LIGHT IN DISTANCE AT LEFT - Frankfort Coast Guard Station, Radio Control House, Second Street at ship channel, Frankfort, Benzie County, MI

  9. Compressed Sensing Based Fingerprint Identification for Wireless Transmitters

    PubMed Central

    Zhao, Caidan; Wu, Xiongpeng; Huang, Lianfen; Yao, Yan; Chang, Yao-Chung

    2014-01-01

    Most of the existing fingerprint identification techniques are unable to distinguish different wireless transmitters, whose emitted signals are highly attenuated, long-distance propagating, and of strong similarity to their transient waveforms. Therefore, this paper proposes a new method to identify different wireless transmitters based on compressed sensing. A data acquisition system is designed to capture the wireless transmitter signals. Complex analytical wavelet transform is used to obtain the envelope of the transient signal, and the corresponding features are extracted by using the compressed sensing theory. Feature selection utilizing minimum redundancy maximum relevance (mRMR) is employed to obtain the optimal feature subsets for identification. The results show that the proposed method is more efficient for the identification of wireless transmitters with similar transient waveforms. PMID:24892053

  10. 47 CFR 25.281 - Automatic Transmitter Identification System (ATIS).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... (ATIS). 25.281 Section 25.281 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations § 25.281 Automatic Transmitter Identification System (ATIS). All satellite uplink transmissions carrying broadband video information shall...

  11. 47 CFR 25.281 - Automatic Transmitter Identification System (ATIS).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... (ATIS). 25.281 Section 25.281 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations § 25.281 Automatic Transmitter Identification System (ATIS). All satellite uplink transmissions carrying broadband video information shall...

  12. 47 CFR 25.281 - Automatic Transmitter Identification System (ATIS).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (ATIS). 25.281 Section 25.281 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations § 25.281 Automatic Transmitter Identification System (ATIS). All satellite uplink transmissions carrying broadband video information shall...

  13. 47 CFR 25.281 - Automatic Transmitter Identification System (ATIS).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... (ATIS). 25.281 Section 25.281 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations § 25.281 Automatic Transmitter Identification System (ATIS). All satellite uplink transmissions carrying broadband video information shall...

  14. Optical materials for space based laser systems

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. M.; Armagan, G.; Byvik, C. E.; Albin, S.

    1989-01-01

    The design features and performance characteristics of a sensitized holmium laser applicable to differential lidar and Doppler windshear measurements are presented, giving attention to the optimal choice of sensitizing/activating dopant ions. This development of a 2-micron region eye-safe laser, where holmium is sensitized by either hulium or erbium, has called for interionic energy transfer processes whose rate will not result in gain-switched pulses that are excessively long for atmospheric lidar and Doppler windshear detection. The application of diamond films for optical component hardening is noted.

  15. 92. View of transmitter building no. 102 first floor coolant ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    92. View of transmitter building no. 102 first floor coolant process water tanks (sodium bisulfate solution), stainless steel, for electronic systems cooling in transmitter and MIP rooms. RCA Services Company 29 September, 1960, official photograph BMEWS Project by unknown photograph, Photographic Services, Riverton, NJ, BMEWS, clear as negative no. A-1226 - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  16. Transmitter Pulse Estimation and Measurements for Airborne TDEM Systems

    NASA Astrophysics Data System (ADS)

    Vetrov, A.; Mejzr, I.

    2013-12-01

    The processing and interpretation of Airborne Time Domain EM data requires precise description of the transmitter parameters, including shape, amplitude and length of the transmitted pulse. There are several ways to measure pulse shape of the transmitter loop. Transmitted pulse can be recorded by a current monitor installed on the loop. The current monitor readings do not give exact image due to own time-domain physical characteristics of the current monitor. Another way is to restore the primary pulse shape from the receiver data recorded on-time, if such is possible. The receiver gives exact image of the primary field projection combined with the ground response, which can be minimized at high altitude pass, usually with a transmitter elevation higher than 1500 ft from the ground. The readings on the receiver are depending on receiver position and orientation. Modeling of airborne TDEM transmitter pulse allows us to compare estimated and measured shape of the pulse and apply required corrections. Airborne TDEM system transmitter pulse shape has been studied by authors while developing P-THEM system. The data has been gathered during in-doors and out-doors ground tests in Canada, as well as during flight tests in Canada and in India. The P-THEM system has three-axes receiver that is suspended on a tow-cable in the midpoint between the transmitter and the helicopter. The P-THEM receiver geometry does not require backing coils to dump the primary field. The system records full-wave data from the receiver and current monitor installed on the transmitter loop, including on-time and off-time data. The modeling of the transmitter pulse allowed us to define the difference between estimated and measured values. The higher accuracy pulse shape can be used for better data processing and interpretation. A developed model can be applied to similar systems and configurations.

  17. Integrating sphere transmissometer for field measurement of leaf transmittance

    NASA Astrophysics Data System (ADS)

    Vanderbilt, V. C.; Dewitt, D. P.; Robinson, B. F.

    1987-12-01

    A simple field-rated transmissometer is described for rapidly determining the normal hemispherical transmittance T(0 deg, 2 pi) of leaves measured in situ in the four Landsat wavelength bands. The transmissometer requires direct solar illumination of the leaf sample. It collects the transmitted light with an integrating sphere and measures the collected light using a commercially available radiometer. The transmittances determined by the transmissometer are comparable with those measured by a labortory spectrophotometer with an integrating sphere attachment.

  18. Photonic integrated transmitter and receiver for NG-PON2

    NASA Astrophysics Data System (ADS)

    Tavares, Ana; Lopes, Ana; Rodrigues, Cláudio; Mãocheia, Paulo; Mendes, Tiago; Brandão, Simão.; Rodrigues, Francisco; Ferreira, Ricardo; Teixeira, António

    2014-08-01

    In this paper the authors present a monolithic Photonic Integrated Circuit which includes a transmitter and a receiver for NG-PON2. With this layout it is possible to build an OLT and, by redesigning some filters, also an ONU. This technology allows reducing the losses in the transmitter and in the receiver, increasing power budget, and also reducing the OEO conversions, which has been a major problem that operators want to surpass.

  19. 15. View of southeasterly side of transmitter building no. 102 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. View of southeasterly side of transmitter building no. 102 with TR in middle and small satcom communication dome lower right. Note site well system building to lower right of transmitter building no. 102 southeast corner. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  20. 14. View of southerly side of transmitter building no. 101 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. View of southerly side of transmitter building no. 101 from west looking easterly showing radar scanner building no. 104 to right with passageway link between, abandoned radome on top of transmitter building no. 101 and DR 1 antenna in background. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  1. 12. View from east side of corner of transmitter building ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. View from east side of corner of transmitter building no. 102 looking over top of utilidor passageway link, DR 2 antenna in background left and abandoned radome on top of transmitter building no. 101. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  2. Preening behavior of adult gyrfalcons tagged with backpack transmitters

    USGS Publications Warehouse

    Booms, T.L.; Schempf, P.F.; Fuller, M.R.

    2011-01-01

    Radio transmitters provide data that enhance understanding of raptor biology (Walls and Kenward 2007) and are now used to answer a multitude of research questions (Meyburg and Fuller 2007). However, transmitters affect the birds that carry them (Barron et al. 2010), and it is important to document and evaluate such effects (Casper 2009). For example, decreased survival has been documented in Prairie Falcons (Falco mexicanus; Steenhof et al. 2006), Northern Goshawks (Accipiter gentilis; Reynolds et al. 2004), and Spotted Owls (Strix occidentalis; Paton et al. 1991) tagged with radio transmitters. However, no such effects were reported for Peregrine Falcons (Falco peregrinus; Fuller et al. 1998, McGrady et al. 2002) and a number of other species (Kenward 2001). White and Garrott (1990) noted that in general, animals tagged with radio transmitters often altered their behaviors for 1–14 d after release during an adjustment period that included increased preening and grooming frequencies. Although more than 90 Gyrfalcons (Falco rusticolus) have been tagged with radio transmitters (e.g., Burnham 2007, McIntyre et al. 2009, T. Booms unpubl. data), the effects of transmitters on this species are not well documented. Anecdotal information suggests some Gyrfalcons might be negatively affected by radio-tagging (Booms et al. 2008). As part of a study investigating Gyrfalcon breeding biology, we conducted opportunistic, focused observations on two radio-tagged adult female Gyrfalcons and their unmarked mates. We here describe and quantify preening behavior of Gyrfalcons shortly after radio-tagging.

  3. Effects of radio transmitters on migrating wood thrushes

    USGS Publications Warehouse

    Powell, L.A.; Krementz, D.G.; Lang, J.D.; Conroy, M.J.

    1998-01-01

    We quantified the effects of radio transmitters on Wood Thrushes (Hylocichla mustelina) using 4 yr of banding and telemetry data from Piedmont National Wildlife Refuge, Georgia. Flight performance models suggest that the 1.6-g transmitter shortens the migratory range of Wood Thrushes by only 60 km, and the estimated migratory range is adequate to accomplish migration even with limited fat stores. We used two strengths of line, 5- and 9-kg test-strength braided Dacron, to attach the transmitters using the thigh-harness method. We recaptured 13 returning radio-marked Wood Thrushes, seven of which were still marked. Six of the seven birds marked with the 5-kg test harnesses lost their transmitters within 1 yr while all six of the 9-kg test harnesses were still attached up to 21 mo later. Radio-marking did not reduce the return rates of adults and immatures, and the transmitters did not cause radio-marked birds to lose more mass than banded-only birds. Wood Thrushes can successfully carry a transmitter during migration with no detectable negative effects. We recommend continued use of the thigh-harness method, but we encourage the use of 5-kg cotton line.

  4. UV transmittance during the crosslinking procedure: tunable treatment

    NASA Astrophysics Data System (ADS)

    Lincoln, Victor A. C.; Mello, Marcio M.; Ventura, Liliane

    2014-02-01

    The transmittance of UVA light through the in vitro human cornea over the thickness of 400um during the corneal collagen cross-linking procedure has been measured using an optical fiber (600 μm core diameter) fixed just before the cornea and attached to Spectrophotometer. The 10 corneas, (average of 6 days post-mortem) were washed with saline and cross-linked with the currently used protocol. To enhance absorption of UV radiation, Riboflavin solution (0.1% and 400 mOsm) was applied prior to and during exposure. The UVA beam - 365nm +/- 5nm at 3mW/cm2 +/- 0.003mW/cm2 - was focused directly onto the corneal stroma. The measured average transmittance of the cornea without Riboflavin was 64.1%. Preceding the irradiation but after 6 applications of Riboflavin at 5min intervals (total of 30min) transmittance decreased to 21.1%. The 30min of irradiation were then accompanied by an additional 6 applications of Riboflavin at 5min intervals (for a total of treatment time of 1h), resulting in a further decrease in transmittance to 12.2%, which is in agreement with current literature. The average transmittance in terms of energy during the 30 minutes irradiation procedure fluctuated from 0.63 to 0.37 mW/cm2. These results indicate different levels of UV transmittance during treatment, leading to consider a new personalized treatment with tunable UV power irradiation.

  5. Design Parameters of a Miniaturized Piezoelectric Underwater Acoustic Transmitter

    SciTech Connect

    Li, Huidong; Deng, Zhiqun; Yuan, Yong; Carlson, Thomas J.

    2012-07-02

    The Juvenile Salmon Acoustic Telemetry System (JSATS) project supported by the U.S. Army Corps of Engineers, Portland District, has yielded the smallest acoustic fish tag transmitter commercially available to date. In order to study even smaller fish populations and make the transmitter injectable by needles, the JSATS acoustic micro transmitter needs to be further downsized. As part of the transmitter downsizing effort some of the design parameters of the lead zirconate titanate (PZT) ceramic tube transducer in the transmitter were studied, including the type of PZT, the backing material, the necessary drive voltage, the transmitting bandwidth and the length of the transducer. It was found that, to satisfy the 156-dB source level requirement of JSATS, a square wave with a 10-volt amplitude is required to drive 'soft' PZT transducers. PZT-5H demonstrated the best source level performance. For Navy types I and II, 16 volts or 18 volts were needed. Ethylene-propylene-diene monomer (EPDM) closed-cell foam was found to be the backing material providing the highest source level. The effect of tube length on the source level is also demonstrated in this paper, providing quantitative information for downsizing of small piezoelectric transmitters.

  6. Canopy light transmittance in Douglas-fir--western hemlock stands.

    PubMed

    Parker, Geoffrey G; Davis, Melinda M; Chapotin, Saharah Moon

    2002-02-01

    We measured vertical and horizontal variation in canopy transmittance of photosynthetically active radiation in five Pseudotsuga menziesii (Mirb.) Franco-Tsuga heterophylla (Raf.) Sarg. (Douglas-fir-western hemlock) stands in the central Cascades of southern Washington to determine how stand structure and age affect the forest light environment. The shape of the mean transmittance profile was related to stand height, but height of mean maximum transmittance was progressively lower than maximum tree height in older stands. The vertical rate of attenuation declined with stand age in both the overstory and understory. A classification of vertical light zones based on the mean and variance of transmittance showed a progressive widening of the bright (low variance and high mean) and transition (high variance and rapid vertical change) zones in older stands, whereas the dim zone (low variance and mean) narrowed. The zone of maximum canopy surface area in height profiles, estimated by inversion of transmittance profiles, changed from relatively high in the canopy in most young stands ("top-heavy") to lower in the canopy in older stands ("bottom-heavy"). In the understory, all stands had similar mean transmittances, but the spatial scale of variation increased with stand age and increasing crown size. The angular distribution of openness was similar in all stands, though the older stands were less open at all angles than the younger stands. Understory openness was generally unrelated to transmittance in the canopy above. Whole-canopy leaf area indices, estimated using three methods of inverting light measurements, showed little correspondence across methods. The observed patterns in light environment are consistent with structural changes occurring during stand development, particularly the diversification of crowns, the creation of openings of various sizes and the elaboration of the outer canopy surface. The ensemble of measurements has potential use in distinguishing

  7. 47 CFR 22.573 - Use of base transmitters as repeaters.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Use of base transmitters as repeaters. 22.573... of base transmitters as repeaters. As an additional function, base transmitters may be used as repeaters. Licensees must be able to turn the base transmitter on or off from the control point...

  8. 47 CFR 22.573 - Use of base transmitters as repeaters.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Use of base transmitters as repeaters. 22.573... of base transmitters as repeaters. As an additional function, base transmitters may be used as repeaters. Licensees must be able to turn the base transmitter on or off from the control point...

  9. 47 CFR 22.573 - Use of base transmitters as repeaters.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Use of base transmitters as repeaters. 22.573... of base transmitters as repeaters. As an additional function, base transmitters may be used as repeaters. Licensees must be able to turn the base transmitter on or off from the control point...

  10. 47 CFR 22.573 - Use of base transmitters as repeaters.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Use of base transmitters as repeaters. 22.573... of base transmitters as repeaters. As an additional function, base transmitters may be used as repeaters. Licensees must be able to turn the base transmitter on or off from the control point...

  11. 47 CFR 22.573 - Use of base transmitters as repeaters.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Use of base transmitters as repeaters. 22.573... of base transmitters as repeaters. As an additional function, base transmitters may be used as repeaters. Licensees must be able to turn the base transmitter on or off from the control point...

  12. 47 CFR 90.475 - Operation of internal transmitter control systems in specially equipped systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Control Internal Transmitter Control Systems § 90.475 Operation of internal transmitter control systems in specially equipped systems. (a) An internal transmitter control system need not be designed to meet the... premises controlled by the licensee. (2) An internal transmitter control system may be used in...

  13. 47 CFR 90.475 - Operation of internal transmitter control systems in specially equipped systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Operation of internal transmitter control... Control Internal Transmitter Control Systems § 90.475 Operation of internal transmitter control systems in specially equipped systems. (a) An internal transmitter control system need not be designed to meet...

  14. Stabilized cleaved-coupled cavity laser

    SciTech Connect

    Olsson, N.A.; Tsang, W.T.

    1988-11-15

    This patent describes a light transmitter comprising a cleaved-coupled cavity laser comprising a laser section and a modulator section, means for measuring at least one characteristic of the light output from one of the sections with respect to the current through the modulator section; and feedback means using at least one characteristic to maintain the output at a desired spectral value.

  15. Effects of radio transmitters on nesting captive mallards

    USGS Publications Warehouse

    Houston, Robert A.; Greenwood, Raymond J.

    1993-01-01

    Radio packages may subtly affect bird behavior and condition, and thus could bias results from studies using this technique. To assess effects on reproduction of mallards (Anas platyrhynchos), we tested 3 types of back-mounted radio packages on captive females. Eight paired females were randomly assigned to each of 4 treatments: 4-g transmitter attached with sutures and glue, 10-g or 18-g transmitter attached with a harness, and no transmitter (control). All mallards were fed ad libitum. No differences were detected among treatments in number of clutches, clutch size, nesting interval, egg mass, or body mass; powers (range = 0.15-0.48) of tests were low. Feather wear and skin irritation around radio packages were minimal. Birds retained sutured transmitters for an average of 43.5 days (range = 3-106 days) and harness transmitters for the duration of the study (106 days). Sutures were not reliable and presently are not recommended as an attachment method. Caution is advised in applying these results to radio-equipped mallards in the wild.

  16. Performance of implantable satellite transmitters in diving seabirds

    USGS Publications Warehouse

    Hatch, Shyla A.; Meyers, P.M.; Mulcahy, D.M.; Douglas, D.C.

    2000-01-01

    We report on the first deployment of satellite transmitters in large alcids. In 1995 and 1996, we surgically implanted 51 transmitters in Common and Thick-billed murres (Uria aalge and U. lomvia) and Tufted Puffins (Fratercula cirrhata) at three colonies in Alaska. These devices furnished more than 2,900 locations over succeeding months (eight months maximum transmitter life), some 30-40% of which had calculated errors of <1,000 m. We considered other data to be reliable if locations were repetitive within a short period of time. As measures of data collection efficiency, we calculated location indices (number of locations per hour of transmission) of 0.44 during the breeding season and 0.35 overall. Those values compared favorably with satellite transmitters previously deployed on large mammals at similar latitudes. Transmitters did not last as long as expected because lithium batteries tended to self-discharge when kept at the high internal temperature of a bird. Most importantly, we encountered high mortality of instrumented birds, especially in the interval from 11-20 days after release. Our results suggest that radio transmission itself somehow impaired normal feeding behavior or otherwise compromised the birds' health. Those two problems (battery life and bird mortality) will need to be solved before implantable devices can be applied effectively to the same or similar species in the future. Received 24 August 1999, accepted 10 October 1999.

  17. An Energy Harvesting Underwater Acoustic Transmitter for Aquatic Animals.

    PubMed

    Li, Huidong; Tian, Chuan; Lu, Jun; Myjak, Mitchell J; Martinez, Jayson J; Brown, Richard S; Deng, Zhiqun Daniel

    2016-01-01

    Acoustic telemetry is the primary method to actively track aquatic animals for behavioral studies. However, the small storage capacities of the batteries used in the transmitters limit the time that the implanted animals can be studied. In this research, we developed and implemented a battery-free acoustic transmitter that uses a flexible piezoelectric beam to harvest energy from fish swimming as the power source. The transmitter sends out a unique identification code with a sufficiently strong signal (150 dB, ref: 1 μPa at 1 meter) that has a detection range of up to 100 meters. Two prototypes, 100 mm and 77 mm long, respectively, weighing only about 1 gram or less in air, were sub-dermally implanted in two species of live fish. Transmissions were successfully detected as the fish swam in a natural manner. This represents the first known implanted energy-harvesting transmitter demonstrated in vivo. Successful development of this transmitter greatly expands the potential for long-term studies of the behaviors of aquatic animals and for subsequently developing strategies to mitigate the environmental impacts of renewable energy systems. PMID:27647426

  18. A taping method for external transmitter attachment on aquatic snakes

    USGS Publications Warehouse

    Wylie, G.D.; Smith, J.J.; Amarello, M.; Casazza, M.L.

    2011-01-01

    Radio telemetry is extremely useful for studying habitat use and movements of free ranging snakes. Surgically implanting radio transmitters into the body cavity of snakes is standard practice in most studies (e.g., Reinert and Cundall 1982; Weatherhead and Blouin-Demers 2004), but this implanting method has its drawbacks. Surgery itself is risky for individual snakes because of the potential for infection or incomplete healing of the incision site. Also, transmitters that are small enough to be carried by small or slender snakes have a relatively short battery life and need to be removed or replaced often, thus requiring frequent surgeries. In rare or endangered snake species, the risk of using invasive implantation surgery may not be merited. External attachment methods are relatively non-invasive and allow removal and replacement of radio transmitters on smaller snakes. The Giant Gartersnake (Thamnophis gigas) is a semi-aquatic snake endemic to wetlands of the Central Valley of California, USA, and is federally and state listed as threatened (U.S. Fish and Wildlife Service 1999). Telemetry studies of the habitat use and movements of this species typically used surgically implanted radio transmitters, but this method is limited to larger snakes, primarily females, because of size requirements for surgery (> 250 g). To overcome difficulties and biases associated with radio telemetry of T. gigas, we developed and evaluated several alternative techniques to attach external radio transmitters using tape.

  19. An Energy Harvesting Underwater Acoustic Transmitter for Aquatic Animals.

    PubMed

    Li, Huidong; Tian, Chuan; Lu, Jun; Myjak, Mitchell J; Martinez, Jayson J; Brown, Richard S; Deng, Zhiqun Daniel

    2016-09-20

    Acoustic telemetry is the primary method to actively track aquatic animals for behavioral studies. However, the small storage capacities of the batteries used in the transmitters limit the time that the implanted animals can be studied. In this research, we developed and implemented a battery-free acoustic transmitter that uses a flexible piezoelectric beam to harvest energy from fish swimming as the power source. The transmitter sends out a unique identification code with a sufficiently strong signal (150 dB, ref: 1 μPa at 1 meter) that has a detection range of up to 100 meters. Two prototypes, 100 mm and 77 mm long, respectively, weighing only about 1 gram or less in air, were sub-dermally implanted in two species of live fish. Transmissions were successfully detected as the fish swam in a natural manner. This represents the first known implanted energy-harvesting transmitter demonstrated in vivo. Successful development of this transmitter greatly expands the potential for long-term studies of the behaviors of aquatic animals and for subsequently developing strategies to mitigate the environmental impacts of renewable energy systems.

  20. An Energy Harvesting Underwater Acoustic Transmitter for Aquatic Animals

    PubMed Central

    Li, Huidong; Tian, Chuan; Lu, Jun; Myjak, Mitchell J.; Martinez, Jayson J.; Brown, Richard S.; Deng, Zhiqun Daniel

    2016-01-01

    Acoustic telemetry is the primary method to actively track aquatic animals for behavioral studies. However, the small storage capacities of the batteries used in the transmitters limit the time that the implanted animals can be studied. In this research, we developed and implemented a battery-free acoustic transmitter that uses a flexible piezoelectric beam to harvest energy from fish swimming as the power source. The transmitter sends out a unique identification code with a sufficiently strong signal (150 dB, ref: 1 μPa at 1 meter) that has a detection range of up to 100 meters. Two prototypes, 100 mm and 77 mm long, respectively, weighing only about 1 gram or less in air, were sub-dermally implanted in two species of live fish. Transmissions were successfully detected as the fish swam in a natural manner. This represents the first known implanted energy-harvesting transmitter demonstrated in vivo. Successful development of this transmitter greatly expands the potential for long-term studies of the behaviors of aquatic animals and for subsequently developing strategies to mitigate the environmental impacts of renewable energy systems. PMID:27647426

  1. Microminiature radio frequency transmitter for communication and tracking applications

    NASA Astrophysics Data System (ADS)

    Crutcher, Richard I.; Emery, Mike S.; Falter, Kelly G.; Nowlin, C. H.; Rochelle, Jim M.; Clonts, Lloyd G.

    1997-02-01

    A micro-miniature radio frequency (rf) transmitter has been developed and demonstrated by the Oak Ridge National Laboratory. The objective of the rf transmitter development was to maximize the transmission distance while drastically shrinking the overall transmitter size, including antenna. Based on analysis and testing, an application-specific integrated circuit (ASIC) with a 16-GHz gallium arsenide (GaAs) oscillator and integrated on-chip antenna was designed and fabricated using microwave monolithic integrated circuit (MMIC) technology. Details of the development and the results of various field tests are discussed. The rf transmitter is applicable to covert surveillance and tracking scenarios due to its small size of 2.2 multiplied by 2.2 mm, including the antenna. Additionally, the 16-GHz frequency is well above the operational range of consumer-grade radio scanners, providing a degree of protection from unauthorized interception. Variations of the transmitter design have been demonstrated for tracking and tagging beacons, transmission of digital data, and transmission of real-time analog video from a surveillance camera. Preliminary laboratory measurements indicate adaptability to direct-sequence spread-spectrum transmission, providing a low probability of intercept and/or detection. Concepts related to law enforcement applications are presented.

  2. An Energy Harvesting Underwater Acoustic Transmitter for Aquatic Animals

    NASA Astrophysics Data System (ADS)

    Li, Huidong; Tian, Chuan; Lu, Jun; Myjak, Mitchell J.; Martinez, Jayson J.; Brown, Richard S.; Deng, Zhiqun Daniel

    2016-09-01

    Acoustic telemetry is the primary method to actively track aquatic animals for behavioral studies. However, the small storage capacities of the batteries used in the transmitters limit the time that the implanted animals can be studied. In this research, we developed and implemented a battery-free acoustic transmitter that uses a flexible piezoelectric beam to harvest energy from fish swimming as the power source. The transmitter sends out a unique identification code with a sufficiently strong signal (150 dB, ref: 1 μPa at 1 meter) that has a detection range of up to 100 meters. Two prototypes, 100 mm and 77 mm long, respectively, weighing only about 1 gram or less in air, were sub-dermally implanted in two species of live fish. Transmissions were successfully detected as the fish swam in a natural manner. This represents the first known implanted energy-harvesting transmitter demonstrated in vivo. Successful development of this transmitter greatly expands the potential for long-term studies of the behaviors of aquatic animals and for subsequently developing strategies to mitigate the environmental impacts of renewable energy systems.

  3. Aging and environmental tolerance of an optical transmitter for the ATLAS Phase-I upgrade at the LHC

    NASA Astrophysics Data System (ADS)

    Chang, F. X.; Chang, H. T.; Duh, T. S.; Hayamizu, T.; Hou, S.; Hu, X.; Liu, C.; Liu, T.; Sakemi, Y.; Schwarz, T.; Teng, P. K.; Tsai, P. R.; Wang, C. H.; Wang, S. Y.; Yang, Y.; Ye, J.

    2016-09-01

    The dual channel Miniature optical Transmitter (MTx) is developed for the ATLAS Phase-I upgrade requiring durable performance in the Large Hadron Collider environment. The data transmission has achieved 8 Gbps per channel with a custom-designed LOCld laser driver and 850 nm VCSELs packaged in transmitter optical sub-assemblies (TOSAs). The performance of the MTx opto-electronics is evaluated. Accelerated aging tests of the VCSELs were conducted in a chamber at 85 °C, 85% relative humidity, with TOSA and bare-die samples prepared in non-hermetic condition. Radiation tolerance of the VCSELs was investigated with 30 MeV and 70 MeV protons. The radiation induced effects in data transmission were investigated for light-power degradation and parameters of eye-diagrams.

  4. Study of precipitant systems by computerised simulation. Influence of optical elements on the noise associated with the transmittance.

    PubMed

    Poce-Fatou, J A; Alcántara, R; Martín, J

    2001-09-01

    The transmittance signal of a precipitant system measured with a focused laser beam carries associated noise coming from several sources. In this work, we have studied the influence of the focal parameters (wavelength, focal length and prefocused radius of the beam) on the maximum noise reached in equivalent nucleation processes. For this purpose, a simulation program of precipitating systems, designed in FORTRAN 90, has been developed. The program generates simulated transmittances, which are processed by another computer program to extract associated noise. Wide ranges of values of the focal parameters have been analysed, finding relationships between the maximum noise and the focal parameters. They have been justified in connection with the changes observed in the radial parameters, which define the size and shape of the focused path. PMID:11513240

  5. Experimental Realization of Tunable Metamaterial Hyper-transmitter.

    PubMed

    Yoo, Young Joon; Yi, Changhyun; Hwang, Ji Sub; Kim, Young Ju; Park, Sang Yoon; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2016-01-01

    We realized the tunable metamaterial hyper-transmitter in the microwave range utilizing simple planar meta-structure. The single-layer metamaterial hyper-transmitter shows that the transmission peak occurs at 14 GHz. In case of the dual-layer one, it is possible to control the transmission peak from 5 to 10 GHz. Moreover, all the transmission peaks reveal transmission over 100%. We experimentally and theoretically investigated these phenomena through 3-dimensional simulation and measurement. The reason for being over 100% is also elucidated. The suggested hyper-transmitter can be used, for example, in enhancing the operating distance of the electromagnetic wave in Wi-Fi, military radar, wireless power transfer and self-driving car. PMID:27629804

  6. Experimental Realization of Tunable Metamaterial Hyper-transmitter

    PubMed Central

    Yoo, Young Joon; Yi, Changhyun; Hwang, Ji Sub; Kim, Young Ju; Park, Sang Yoon; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2016-01-01

    We realized the tunable metamaterial hyper-transmitter in the microwave range utilizing simple planar meta-structure. The single-layer metamaterial hyper-transmitter shows that the transmission peak occurs at 14 GHz. In case of the dual-layer one, it is possible to control the transmission peak from 5 to 10 GHz. Moreover, all the transmission peaks reveal transmission over 100%. We experimentally and theoretically investigated these phenomena through 3-dimensional simulation and measurement. The reason for being over 100% is also elucidated. The suggested hyper-transmitter can be used, for example, in enhancing the operating distance of the electromagnetic wave in Wi-Fi, military radar, wireless power transfer and self-driving car. PMID:27629804

  7. Experimental Realization of Tunable Metamaterial Hyper-transmitter

    NASA Astrophysics Data System (ADS)

    Yoo, Young Joon; Yi, Changhyun; Hwang, Ji Sub; Kim, Young Ju; Park, Sang Yoon; Kim, Ki Won; Rhee, Joo Yull; Lee, Youngpak

    2016-09-01

    We realized the tunable metamaterial hyper-transmitter in the microwave range utilizing simple planar meta-structure. The single-layer metamaterial hyper-transmitter shows that the transmission peak occurs at 14 GHz. In case of the dual-layer one, it is possible to control the transmission peak from 5 to 10 GHz. Moreover, all the transmission peaks reveal transmission over 100%. We experimentally and theoretically investigated these phenomena through 3-dimensional simulation and measurement. The reason for being over 100% is also elucidated. The suggested hyper-transmitter can be used, for example, in enhancing the operating distance of the electromagnetic wave in Wi-Fi, military radar, wireless power transfer and self-driving car.

  8. Effects of implanted transmitters on adult bluegills at two temperatures

    USGS Publications Warehouse

    Knights, Brent C.; Lasee, Becky A.

    1996-01-01

    Laterally compressed panfishes are small and have limited intraperitoneal space; thus, they may suffer adversely from surgically implanted transmitters even if the transmitter meets the generally recommended ratio of transmitter weight to fish weight of 2%. We studied the effects of intraperitoneal transmitters (2.81 g) on survival, growth, healing, and health of bluegills Lepomis macrochirus (mean weight 133 g) held for 8 weeks at 6 degree C and 20 degree C. Radio-tagged bluegills at 20 degree C had a mortality rate of 10% and tag loss rate of 15%. At 6 degree C, bluegills had no mortality or tag loss. Radio-tagged and reference fish fed in both 20 degree C raceways; however, a few reference fish appeared dominant at feeding time. This dominance by a few reference fish was also indicated by a large weight gain for three reference fish in each 20 degree C raceway. At 6 degree C, neither reference fish nor radio-tagged fish fed activity. Radio-tagged fish held at 20 degree C exhibited pelvic fin erosion, erythema and necrosis at the antenna exit and at suture insertions, and lost or loose sutures, effects not observed in other test fishes. Examination of fish held at 20 degree C also showed enclosure of the transmitters in a fibrous capsule and adhesion of visceral organs. Epithelialization over the incision occurred in radio-tagged bluegills at both temperatures, but there was little further healing at 6 degree C. At 20 degree C, tissue responses included chronic inflammation and dermal granulation. Radio-tagged fish did not appear to be more susceptible than reference fish to bacterial infection. Mortality, adverse morphological effects, altered behavior, and limited healing in bluegills suggest that implanted transmitters impaired their health. Thus, movement and habitat use data collected by telemetry for this species and perhaps for other panfishes should be interpreted with caution.

  9. Studies relating to FM television and telemetry transmitters

    NASA Technical Reports Server (NTRS)

    Albritton, W. P.; Honnell, M. A.

    1972-01-01

    The Auburn University Model S-2 FM television transmitter was examined to determine if the performance and reliability could be improved by application of new techniques and devices developed since completion of the original design work. In particular this study examined the possibility of increased use of integrated circuits. It was determined that improvements in both performance and reliability were possible. In addition a study was conducted to determine the feasibility of converting the transmitter to handle telemetry signals. The study revealed that this conversion was feasible and the modifications were made to the prototype model for verification.

  10. Transmittance ratio constrained retrieval technique for lidar cirrus measurements.

    PubMed

    Su, Jia; McCormick, M Patrick; Liu, Zhaoyan; Lee, Robert B; Leavor, Kevin R; Lei, Liqiao

    2012-05-01

    This letter describes a lidar retrieval technique that uses the transmittance ratio as a constraint to determine an average lidar ratio as well as extinction and backscatter coefficients of transparent cirrus clouds. The cloud transmittance ratio is directly obtained from two adjacent elastic lidar backscatter signals. The technique can be applied to cirrus measurements where neither the molecular scattering dominant signals above and below the cloud layer are found nor cloudfree reference profiles are available. The technique has been tested with simulated lidar signals and applied to backscatter lidar measurements at Hampton University, Hampton, Virginia.

  11. Passive remote sensing of slant path transmittance from aircraft.

    PubMed

    Cogan, J L

    1988-08-01

    This paper presents a passive method for computation of thermal IR transmittance over slant paths. This double viewing angle technique utilizes data gathered by a radiometer or imager carried by a manned or unmanned aircraft. A sensitivity analysis showed the effect of changes or errors in input parameters on calculated transmittances. The analysis suggested the applicability and limitations of this method. Accuracies attainable through the use of the double viewing angle method appear to be similar to those from more complex techniques for many atmospheric conditions. PMID:20531929

  12. Transmittance characteristics of plasmonic graphene ribbons with a wing

    NASA Astrophysics Data System (ADS)

    Yuan, Lin; Yan, Xin; Wang, Yueke; Sang, Tian; Yang, Guofeng

    2016-09-01

    We numerically investigate the transmittance characteristics of graphene ribbons with a wing by the finite element method. By determining the dispersion relation of edge graphene plasmon (EGP) modes and analyzing the mode distributions, it is considered that the transmission dips originate from the resonances of three EGP modes, namely, the symmetrical EGPs, antisymmetrical EGPs, and EGPs of a semi-infinite sheet. By changing the width and length of the wing, it was further confirmed that transmission dips originate from the EGP modes. Owing to the tunable permittivity of graphene by adjusting the gate voltage, the transmittance dips can be easily tuned.

  13. Transmittance characteristics and tunable sensor performances of plasmonic graphene ribbons

    NASA Astrophysics Data System (ADS)

    Yan, Xin; Yuan, Lin; Wang, Yueke; Sang, Tian; Yang, Guofeng

    2016-08-01

    We investigate the transmittance characteristics of graphene ribbons numerically. It is found that the transmission dips originate from the transverse and longitudinal resonances of edge graphene plasmon modes, supported by the graphene ribbon resonator. The environmental refractive index changes are detected by measuring the resulting spectral shifts of the resonant transmission dip, so the graphene ribbons can be applied to plasmonic sensor in infrared. Simulation results show that sensing performances for each resonant mode are similar, and figure of merit can be up to 6. Beside, thanks to the tunable permittivity of graphene by bias voltages, the transmittance spectra and sensor performances can be easily tuned.

  14. Holographic Laser-Protective Eyewear

    NASA Astrophysics Data System (ADS)

    Tedesco, James M.

    1988-04-01

    Holographic filters in spectacle lenses, helmet visors and other types of substrates have been proposed for eye protection against visible lasers. Dyes and filter glasses, commonly used as laser protection at visible wavelengths, typically suffer from poor visual transmittance. Holographic filters offer potentially high visual transmittance due to a narrow spectral notch, but the angular dependence of the spectral notch position dictates a tradeoff between eye protection and visual transmittance. The relative merits of various exposure and substrate configurations for laser-protective eyewear are compared. Emphasis is placed on single-beam exposure, surface-conformal fringe structures in which the local Bragg angle is determined by the fringe spacing as opposed to the fringe tilt. This type of hologram is readily made free from flare or multiple images in transmission. Performance is evaluated in terms of visual transmittance versus eye protection, including retinal area and eye rotation. The relationship between angular and spectral response of holographic laser filters determines the exposure source for optimum performance to be roughly coincident with the center of eye rotation, regardless of the substrate geometry. Performance may be improved by locating the filters a greater distance from the eye. A more dramatic improvement in performance may be achieved by increasing the curvature of the substrate so that it is concentric with the eye.

  15. RF-modulated pulsed fiber optic lidar transmitter for improved underwater imaging and communications

    NASA Astrophysics Data System (ADS)

    Kimpel, F.; Chen, Y.; Fouron, J.-L.; Akbulut, M.; Engin, D.; Gupta, S.

    2011-03-01

    We present results on the design, development and initial testing of a fiber-optic based RF-modulated lidar transmitter operating at 532nm, for underwater imaging application in littoral waters. The design implementation is based on using state-of-the-art high-speed FPGAs, thereby producing optical waveforms with arbitrary digital-RF-modulated pulse patterns with carrier frequencies >= 3GHz, with a repetition rate of 0.5-1MHz, and with average powers >=5W (at 532nm). Use of RF-modulated bursts above 500MHz, instead of single optical pulse lidar detection, reduces the effect of volumetric backscatter for underwater imaging application, leading to an improved signal-to-noise-ratio (SNR) and contrast, for a given range. Initial underwater target detection tests conducted at Patuxent River Naval Air Station, MD, in a large water-tank facility, validates the advantages of this hybrid-lidar-radar (HLR) approach for improved underwater imaging, over a wide range of turbidity levels and both white and black targets. The compact, robust and power-efficient fiber laser architecture lends very well to lidar sensor integration on unmanned-underwater-vehicle (UUV) platforms. HLR transmitters can also provide similar advantages in active-sensing situations dominated by continuous backscatter, e.g. underwater communications, imaging through smoke and fire environment, rotor-craft landing in degraded visual environment, and pointing-tracking of active-EO sensors through fog.

  16. NASA Space Laser Technology

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.

    2015-01-01

    Over the next two decades, the number of space based laser missions for mapping, spectroscopy, remote sensing and other scientific investigations will increase several fold. The demand for high wall-plug efficiency, low noise, narrow linewidth laser systems to meet different systems requirements that can reliably operate over the life of a mission will be high. The general trends will be for spatial quality very close to the diffraction limit, improved spectral performance, increased wall-plug efficiency and multi-beam processing. Improved spectral performance will include narrower spectral width (very near the transform limit), increased wavelength stability and or tuning (depending on application) and lasers reaching a wider range of wavelengths stretching into the mid-infrared and the near ultraviolet. We are actively developing high efficiency laser transmitter and high-sensitivity laser receiver systems that are suitable for spaceborne applications.

  17. 47 CFR 95.667 - CB transmitter power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... transmitter power. The dissipation rating of all the semiconductors or electron tubes which supply RF power to... semiconductor. These values may be temperature de-rated by no more than 50 °C. For an electron tube, the... the manufacturer of the electron tube....

  18. 47 CFR 95.667 - CB transmitter power.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... transmitter power. The dissipation rating of all the semiconductors or electron tubes which supply RF power to... semiconductor. These values may be temperature de-rated by no more than 50 °C. For an electron tube, the... the manufacturer of the electron tube....

  19. 47 CFR 95.667 - CB transmitter power.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... transmitter power. The dissipation rating of all the semiconductors or electron tubes which supply RF power to... semiconductor. These values may be temperature de-rated by no more than 50 °C. For an electron tube, the... the manufacturer of the electron tube....

  20. 47 CFR 95.667 - CB transmitter power.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... transmitter power. The dissipation rating of all the semiconductors or electron tubes which supply RF power to... semiconductor. These values may be temperature de-rated by no more than 50 °C. For an electron tube, the... the manufacturer of the electron tube....

  1. 47 CFR 95.667 - CB transmitter power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... transmitter power. The dissipation rating of all the semiconductors or electron tubes which supply RF power to... semiconductor. These values may be temperature de-rated by no more than 50 °C. For an electron tube, the... the manufacturer of the electron tube....

  2. 47 CFR 74.1250 - Transmitters and associated equipment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Translator Stations and FM Broadcast Booster Stations § 74.1250 Transmitters and associated equipment. (a) FM translator and booster transmitting apparatus, and exciters employed to provide a locally generated and modulated input signal to translator and booster equipment, used by stations authorized under the...

  3. 47 CFR 80.209 - Transmitter frequency tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... 2 For transmitters with digital selective calling emissions 10 Hz. 2 For all other emissions 50 Hz... craft stations: 50 Hz. (4) Band 72-76 MHz: (i) Fixed stations: Operating in the 72.0-73.0 and 75.4-76.0... shown in the following table. Tolerances are given as parts in 106 unless shown in Hz. Frequency...

  4. 14 CFR 91.207 - Emergency locator transmitters.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... batteries (such as water-activated batteries) that are essentially unaffected during probable storage... attached to the airplane as far aft as practicable. (c) Batteries used in the emergency locator... batteries are rechargeable)— (1) When the transmitter has been in use for more than 1 cumulative hour; or...

  5. 34. View of typical work station in transmitter building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. View of typical work station in transmitter building no. 102, second floor, with continental electronics "keying pulse line amplifier trigger pulse AM-3445/FPT9" cabinet at desk. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  6. 26. Perimeter acquisition radar building room #301, transmitter area no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. Perimeter acquisition radar building room #301, transmitter area no. 2; power supply assembly (in foreground) and amplifier modulators - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  7. 70. Transmitter building no. 102, view of typical amplifier modulation ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    70. Transmitter building no. 102, view of typical amplifier modulation system vaults showing Klystron tube in installed position (1 of 2 in each module). - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  8. 10 CFR 455.152 - Transmittal of record on review.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Transmittal of record on review. 455.152 Section 455.152 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION GRANT PROGRAMS FOR SCHOOLS AND HOSPITALS AND BUILDINGS OWNED BY UNITS OF LOCAL GOVERNMENT AND PUBLIC CARE INSTITUTIONS Administrative Review §...

  9. 47 CFR 101.133 - Limitations on use of transmitters.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.133 Limitations on use of transmitters. (a...) Private operational fixed point-to-point microwave stations authorized in this service may communicate...-point microwave licenses may use the same transmitting equipment under the following terms...

  10. 47 CFR 101.133 - Limitations on use of transmitters.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.133 Limitations on use of transmitters. (a...) Private operational fixed point-to-point microwave stations authorized in this service may communicate...-point microwave licenses may use the same transmitting equipment under the following terms...

  11. 47 CFR 101.133 - Limitations on use of transmitters.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.133 Limitations on use of transmitters. (a...) Private operational fixed point-to-point microwave stations authorized in this service may communicate...-point microwave licenses may use the same transmitting equipment under the following terms...

  12. 47 CFR 101.133 - Limitations on use of transmitters.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.133 Limitations on use of transmitters. (a...) Private operational fixed point-to-point microwave stations authorized in this service may communicate...-point microwave licenses may use the same transmitting equipment under the following terms...

  13. 47 CFR 101.133 - Limitations on use of transmitters.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.133 Limitations on use of transmitters. (a...) Private operational fixed point-to-point microwave stations authorized in this service may communicate...-point microwave licenses may use the same transmitting equipment under the following terms...

  14. 119. EQUIPMENT DATA TRANSMITTER (EDT) CONDITIONING PANEL FOR NATIONAL OCEANIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    119. EQUIPMENT DATA TRANSMITTER (EDT) CONDITIONING PANEL FOR NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA) PAYLOADS IN NORTHEAST CORNER OF VEHICLE MECHANICAL SYSTEMS ROOM (111), LSB (BLDG. 770) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  15. 75. Transmitter building no. 102, view of typical radio frequency ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    75. Transmitter building no. 102, view of typical radio frequency switching group for lower antenna A & B and upper antenna A & B and MIP/MWOC automated interface cabinet. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  16. Receivers and Transmitters. Electronics Module 6. Instructor's Guide.

    ERIC Educational Resources Information Center

    Everett, Jim

    This module is the sixth of 10 modules in the competency-based electronics series. Introductory materials include a listing of competencies addressed in the module and a cross-reference table of instructional materials. Two instructional units cover: (1) AM/FM transmitter and receiver basics; and (2) satellite systems, antennas, and analyzers.…

  17. 47 CFR 74.18 - Transmitter control and operation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Transmitter control and operation. 74.18 Section 74.18 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES General; Rules Applicable to All Services in Part 74 §...

  18. Digital staining of pathological tissue specimens using spectral transmittance

    NASA Astrophysics Data System (ADS)

    Bautista, Pinky A.; Abe, Tokiya; Yamaguchi, Masahiro; Yagi, Yukako; Ohyama, Nagaaki

    2005-04-01

    Staining of tissue specimens is a classical procedure in pathological diagnosis to enhance the contrast between tissue components such that identification and classification of these components can be easily performed. In this paper, a framework for digital staining of pathological specimens using the information derived from the L-band spectral transmittance of various pathological tissue components is introduced, particularly the transformation of a Hematoxylin and Eosin (HE) stained specimen to its Masson-Trichrome (MT) stained counterpart. The digital staining framework involves the classification of tissue components, which are highlighted when the specimen is actually stained with MT stain, e.g. fibrosis, from the HE-stained image; and the linear mapping between specific sets of HE and MT stained transmittance spectra through pseudo-inverse procedure to produce the LxL transformation matrices that will be used to transform the HE stained transmittance to its equivalent MT stained transmittance configuration. To generate the digitally stained image, the decisions of multiple quadratic classifiers are pooled to form the weighting factors for the transformation matrices. Initial results of our experiments on liver specimens show the viability of multispectral imaging (MSI) for the implementation of digital staining in the pathological context.

  19. 24. View of lobby area on first floor transmitter building ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. View of lobby area on first floor transmitter building no. 102 looking into controlled access corridor and door system - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  20. 47 CFR 80.203 - Authorization of transmitters for licensing.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... station MF, HF, and VHF transmitters may employ external or internal devices to send synthesized voice... capable of transmitting a synthesized voice message must be certificated as an integral unit. (3) The synthesized voice distress transmission must begin with the words “this is a recording” and should...

  1. 47 CFR 80.203 - Authorization of transmitters for licensing.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... station MF, HF, and VHF transmitters may employ external or internal devices to send synthesized voice... capable of transmitting a synthesized voice message must be certificated as an integral unit. (3) The synthesized voice distress transmission must begin with the words “this is a recording” and should...

  2. 32 CFR 2400.32 - Transmittal of classified information.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... TECHNOLOGY POLICY REGULATIONS TO IMPLEMENT E.O. 12356; OFFICE OF SCIENCE AND TECHNOLOGY POLICY INFORMATION... classified information outside of the Office of Science and Technology Policy shall be in accordance with... 32 National Defense 6 2010-07-01 2010-07-01 false Transmittal of classified information....

  3. 16. View of east side of transmitter building no. 102 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. View of east side of transmitter building no. 102 looking south with TR radome in upper right of photograph and DR 2 antenna in left of photograph. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  4. Transmittance and Radiance Computations for Rocket Engine Plume Environments

    NASA Technical Reports Server (NTRS)

    Tejwani, Gopal D.

    2003-01-01

    Emission and absorption characteristics of several atmospheric and combustion species have been studied and are presented with reference to rocket engine plume environments. The effects of clous, rain, and fog on plume radiance/transmittance has also been studied.Preliminary results for the radiance from the exhaust plume of the space shuttle main engine are shown and discussed.

  5. 14 CFR 91.207 - Emergency locator transmitters.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Emergency locator transmitters. 91.207 Section 91.207 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Equipment,...

  6. 14 CFR 91.207 - Emergency locator transmitters.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Emergency locator transmitters. 91.207 Section 91.207 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Equipment,...

  7. 14 CFR 91.207 - Emergency locator transmitters.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Emergency locator transmitters. 91.207 Section 91.207 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Equipment, Instrument, and Certificate Requirements §...

  8. 48 CFR 805.207 - Preparation and transmittal of synopses.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... AFFAIRS COMPETITION AND ACQUISITION PLANNING PUBLICIZING CONTRACT ACTIONS Synopses of Proposed Contract Actions 805.207 Preparation and transmittal of synopses. (a) When an A/E evaluation board is ready to advertise for A/E services, the board must establish the geographic area within which it will consider...

  9. 71. Transmitter building no. 102, view of arrangement showing the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    71. Transmitter building no. 102, view of arrangement showing the Klystron tube vaults along right side of photograph and capacitor vaults along left side of photograph. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  10. Controlled crumpling of graphene oxide films for tunable optical transmittance.

    PubMed

    Thomas, Abhay V; Andow, Brandon C; Suresh, Shravan; Eksik, Osman; Yin, Jie; Dyson, Anna H; Koratkar, Nikhil

    2015-06-01

    The delamination buckling approach provides a facile means to dynamically control the optical transmittance of extremely flexible and stretchable graphene oxide coatings with fast response time. Such graphene oxide coatings can be deposited by scalable solution-processing methods for potential applications in dynamic glazing.

  11. 47 CFR 74.1250 - Transmitters and associated equipment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Transmitters and associated equipment. 74.1250 Section 74.1250 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES FM Broadcast Translator Stations and FM...

  12. 47 CFR 74.1250 - Transmitters and associated equipment.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Transmitters and associated equipment. 74.1250 Section 74.1250 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES FM Broadcast Translator Stations and FM...

  13. Transmittance of distilled water and sodium-chloride-water solutions

    SciTech Connect

    Kanayama, K.; Baba, H.

    1988-05-01

    The spectral transmittance of pure water and salt water solutions of various concentrations, which are important for the thermal calculation of a solar pond, is measured experimentally for specimen thickness of 1 to 100 mm by means of an autorecording spectro-radiometer inside an air-conditioned room. On the basis of the measured spectral transmittance, the total transmittance of pure and salty waters to 3 m of water depth is calculated as a ratio of the total radiation energy over all wavelengths arriving at any depth from the water surface of the solar pond to the solar radiation incident upon the water surface with various air masses. According to Nielsens' four-partition method, the effective absorption coefficient is calculated for each wavelength band. Lastly, the transmission properties obtained for pure water, i.e., spectral and total transmittances, absorption wavelength band, and effective absorption coefficient, are compared with past results, and those for salty water with various concentrations are compiled as basic data for the use of solar energy by a solar pond.

  14. 74. Transmitter building no. 102, view of radar digital test ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    74. Transmitter building no. 102, view of radar digital test and maintenance cabinet area control panel and date storage system showing ampex tape storage devices. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  15. Why a Letter of Transmittal Should Accompany Annual Financial Reports.

    ERIC Educational Resources Information Center

    Phipps, Bill W.

    1986-01-01

    Explains the importance of comprehensive annual financial reports, including introductory, financial, and statistical sections. Advises school districts to pay special attention to the letter of transmittal, which should provide information on services, financial highlights, economic forecasting, accounting principles used, and other pertinent…

  16. 47 CFR 73.1660 - Acceptability of broadcast transmitters.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Acceptability of broadcast transmitters. 73.1660 Section 73.1660 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES Rules Applicable to All Broadcast Stations § 73.1660 Acceptability...

  17. 32 CFR 2400.32 - Transmittal of classified information.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... TECHNOLOGY POLICY REGULATIONS TO IMPLEMENT E.O. 12356; OFFICE OF SCIENCE AND TECHNOLOGY POLICY INFORMATION... classified information outside of the Office of Science and Technology Policy shall be in accordance with... 32 National Defense 6 2011-07-01 2011-07-01 false Transmittal of classified information....

  18. 47 CFR 73.685 - Transmitter location and antenna system.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... to reduce to a minimum the shadow effect on propagation due to hills and buildings which may reduce... operating on Channels 14-69 with transmitters delivering a peak visual power output of more than 1 kW may... visual power output of 1 kW or less are not limited as to the ratio of maximum to minimum radiation....

  19. 17 CFR 30.12 - Direct foreign order transmittal.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... FOREIGN FUTURES AND FOREIGN OPTIONS TRANSACTIONS § 30.12 Direct foreign order transmittal. (a) Authorized... merchant shall mean any foreign futures or foreign options customer, as defined in § 30.1(c), or its... account of the futures commission merchant's foreign futures and options customer omnibus account; and...

  20. 17. View looking north to transmitter building no. 102 from ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. View looking north to transmitter building no. 102 from south along west side of passageway link with TR radome in background. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  1. 23. View of junction of passageway link with radar transmitter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. View of junction of passageway link with radar transmitter building 102 (view looking south) showing main personnel entrance door. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  2. 61. View of TR spiral access stair system from transmitter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    61. View of TR spiral access stair system from transmitter building no. 102 mezzanine level; note elevator door on right. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  3. 25. Similar view of lobby area on first floor transmitter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. Similar view of lobby area on first floor transmitter building no. 102 looking at door in photograph AK-30-A-24 in closed position showing locking system and restricted access notification. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  4. 85. View of specialized maintenance shop in transmitter building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    85. View of specialized maintenance shop in transmitter building no. 101, showing test bed with meters, power supplies, oscilloscopes, and other electronic test equipment. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  5. Controlled crumpling of graphene oxide films for tunable optical transmittance.

    PubMed

    Thomas, Abhay V; Andow, Brandon C; Suresh, Shravan; Eksik, Osman; Yin, Jie; Dyson, Anna H; Koratkar, Nikhil

    2015-06-01

    The delamination buckling approach provides a facile means to dynamically control the optical transmittance of extremely flexible and stretchable graphene oxide coatings with fast response time. Such graphene oxide coatings can be deposited by scalable solution-processing methods for potential applications in dynamic glazing. PMID:25899342

  6. All-Solid-State UV Transmitter Development for Ozone Sensing Applications

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Singh, Upendra N.; Armstrong, Darrell Jr.

    2009-01-01

    In this paper, recent progress made in the development of an all-solid-state UV transmitter suitable for ozone sensing applications from space based platforms is discussed. A nonlinear optics based UV setup based on Rotated Image Singly Resonant Twisted Rectangle (RISTRA) optical parametric oscillator (OPO) module was effectively coupled to a diode pumped, single longitudinal mode, conductively cooled, short-pulsed, high-energy Nd:YAG laser operating at 1064 nm with 50 Hz PRF. An estimated 10 mJ/pulse with 10% conversion efficiency at 320 nm has been demonstrated limited only by the pump pulse spatial profile. The current arrangement has the potential for obtaining greater than 200 mJ/pulse. Previously, using a flash-lamp pumped Nd:YAG laser with round, top-hat profile, up to 24% IR-UV conversion efficiency was achieved with the same UV module. Efforts are underway to increase the IR-UV conversion efficiency of the all solid-state setup by modifying the pump laser spatial profile along with incorporating improved OPO crystals.

  7. 20 years of Tm:Ho:YLF and LuLF Laser Development for Global Winds Measurements

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Walsh, Brian M.; Yu, Jirong; Petros, Mulugeta; Kavaya, Michael J.; Barnes, Norman P.

    2014-01-01

    NASA Langley Research Center has a long history of developing 2 micron lasers. From fundamental spectroscopy research, theoretical prediction of new materials, laser demonstration and engineering of lidar systems, it has been a very successful program spanning around two decades. This article covers the program development from the early research to the present instrumentation. A brief historical perspective of Tm:Ho work by early researchers is also given.

  8. Piezoelectric transducer design for a miniaturized injectable acoustic transmitter

    DOE PAGESBeta

    Li, Huidong; Jung, Ki Won; Deng, Zhiqun D.

    2015-10-07

    Acoustic telemetry has been an important tool in the last 20 years for studying fish survival and migration behaviors during and after dam passage. This technology uses implantable acoustic transmitters as tags to three-dimensionally track the movement of fish. However, the relatively large weights and sizes of commercially available transmitters limit the populations of fish that could be studied. The surgical implantation procedures required may also injure fish and also incur a significant amount of labor. Therefore, a smaller, lighter, and injectable tag was needed, and similar or better acoustic performance and service life over that provided by existing commercialmore » tags was desired. To develop such a small transmitter, a number of technical challenges, including design optimization of the piezoelectric transducer, needed to be overcome. The goal of our efforts to optimize the transducer focused on improving the average source level in the 180° range in which the transmitter was facing the receiving hydrophone, so as to increase the transmitter’s detection probability. This paper reports the techniques that were explored and developed to achieve this goal. We found that a novel off-center tube transducer improved the average source level of the front half of the transducer by 1.5 dB. An acoustic reflector attached to the back of the transducer also improved the source level by 3 dB when the transducer was pointed toward the receiving hydrophone, although the source level on the sides of the transducer was reduced. We found that too small a gap between the transducer and the component placed behind it resulted in distortion of the beam pattern. To overcome that issue, we connected a tuning inductor in series with the transducer to help optimize the source level. Furthermore, the findings and techniques developed in this work contributed to the successful development and implementation of a new injectable transmitter.« less

  9. Piezoelectric transducer design for a miniaturized injectable acoustic transmitter

    SciTech Connect

    Li, Huidong; Jung, Ki Won; Deng, Zhiqun D.

    2015-10-07

    Acoustic telemetry has been an important tool in the last 20 years for studying fish survival and migration behaviors during and after dam passage. This technology uses implantable acoustic transmitters as tags to three-dimensionally track the movement of fish. However, the relatively large weights and sizes of commercially available transmitters limit the populations of fish that could be studied. The surgical implantation procedures required may also injure fish and also incur a significant amount of labor. Therefore, a smaller, lighter, and injectable tag was needed, and similar or better acoustic performance and service life over that provided by existing commercial tags was desired. To develop such a small transmitter, a number of technical challenges, including design optimization of the piezoelectric transducer, needed to be overcome. The goal of our efforts to optimize the transducer focused on improving the average source level in the 180° range in which the transmitter was facing the receiving hydrophone, so as to increase the transmitter’s detection probability. This paper reports the techniques that were explored and developed to achieve this goal. We found that a novel off-center tube transducer improved the average source level of the front half of the transducer by 1.5 dB. An acoustic reflector attached to the back of the transducer also improved the source level by 3 dB when the transducer was pointed toward the receiving hydrophone, although the source level on the sides of the transducer was reduced. We found that too small a gap between the transducer and the component placed behind it resulted in distortion of the beam pattern. To overcome that issue, we connected a tuning inductor in series with the transducer to help optimize the source level. Furthermore, the findings and techniques developed in this work contributed to the successful development and implementation of a new injectable transmitter.

  10. Underwater laser system

    NASA Astrophysics Data System (ADS)

    Kushina, Mark E.; Heberle, Geoff; Hope, Michael; Crittenden, Ryan M.; Bethel, Michael

    2002-03-01

    We have developed a solid-state laser operating at 532nm for underwater topographic investigations. The laser system is integrated into a torpedo-like 'towed-body', with the military designation of AQS-20. This laser, along with other sophisticated receiver opto-electronic systems enables detailed underwater bathymetry. CEO designed and manufactured the laser portion of this system. The laser sub-system is comprised of two separate parts: the LTU (Laser Transmitter Unit) and the LEU (Laser Electronics Unit). The LTU and LEU where put through Mil-standard testing for vibration, shock and temperature storage and operation extremes as well as Mil-461C EMI/EMC testing. The Nd:YAG laser operates at a 400 Hz pulse repetition frequency and is controlled remotely, tethered to the system controller in a ship or helicopter. Power monitor circuits allow real time laser health monitoring, which enables input parameter adjustments for consistent laser behavior. The towed body moves forward at a constant rate of speed while this underwater LIDAR system gathers data. All heat generated must be conducted into the outer hull of the towed-body and then, to the surrounding ambient ocean water. The water temperature may vary from 0-35 degrees C.

  11. Injection-seeded operation of a Q-switched Cr,Tm,Ho:YAG laser

    NASA Technical Reports Server (NTRS)

    Henderson, Sammy W.; Hale, Charley P.; Magee, James R.

    1991-01-01

    Single-frequency Tm,Ho:YAG lasers operating near 2 microns are attractive sources for several applications including eye-safe laser radar (lidar) and pumping of AgGaSe2 parametric oscillators for efficient generation of longer wavelengths. As part of a program to develop a coherent lidar system using Tm,Ho:YAG lasers, a diode laser-pumped tunable CW single-longitudinal-mode (SLM) Cr:Tm:Ho:YAG laser and a flashlamp-pumped single-transverse-mode Q-switched Cr,Tm,Ho:YAG laser were developed. The CW laser was used to injection-seed the flashlamp-pumped laser, resulting in SLM Q-switched output. Operational characteristics of the CW and Q-switched lasers and injection-seeding results are reported.

  12. Optimization of coherent lidar performance with graded-reflectance transmitter resonator optics in the low equivalent Fresnel number regime.

    PubMed

    Tratt, D M; Bowers, M S

    1996-08-20

    Using a diffractive eigenmode treatment to model the laser output we show that graded-reflectance resonator optics offer significant efficiency benefits over conventional hard-edge coupled unstable resonators in the context of coherent detection lidar applications. Extending previous research pertinent to the high equivalent Fresnel number regime, we have modeled the optimum performance of a notional super-Gaussian coupled cavity as a function of the key resonator parameters in the low equivalent Fresnel number (<3) regime. The findings from this study are applicable to the design of coherent lidar transmitters operated within this regime. PMID:21102907

  13. Spaceflight laser development for future remote sensing applications

    NASA Astrophysics Data System (ADS)

    Yu, Anthony W.; Krainak, Michael A.; Stephen, Mark A.; Abshire, James B.; Harding, David J.; Riris, Haris; Li, Steven X.; Chen, Jeffrey R.; Allan, Graham R.; Numata, Kenji; Wu, Stewart T.; Camp, Jordan B.

    2011-11-01

    At NASA's Goddard Space Flight Center we are developing next generation laser transmitters for future spaceflight, remote instruments including a micropulse altimeter for ice-sheet and sea ice monitoring, laser spectroscopic measurements of atmospheric CO2 and an imaging lidar for high resolution mapping of the Earth's surface. These laser transmitters also have applicability to potential missions to other solar-system bodies for trace gas measurements and surface mapping. In this paper we review NASA spaceflight laser transmitters used to acquire measurements in orbit around Mars, Mercury, Earth and the Moon. We then present an overview of our current spaceflight laser programs and describe their intended uses for remote sensing science and exploration applications.

  14. Optical communication with semiconductor laser diode

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic; Sun, X.

    1989-01-01

    This interim report describes the progress in the construction of a 220 Mbps Q=4 PPM optical communication system that uses a semiconductor laser as the optical transmitter and an avalanche photodiode (APD) as the photodetector. The transmitter electronics have been completed and contain both GaAs and ECL III IC's. The circuit was able to operate at a source binary data rate from 75 Mbps to 290 Mbps with pulse rise and fall times of 400 ps. The pulse shapes of the laser diode and the response from the APD/preamplifier module were also measured.

  15. Inductance effects in the high-power transmitter crowbar system

    NASA Technical Reports Server (NTRS)

    Daeges, J.; Bhanji, A.

    1987-01-01

    The effective protection of a klystron in a high-power transmitter requires the diversion of all stored energy in the protected circuit through an alternate low-impedance path, the crowbar, such that less than 1 joule of energy is dumped into the klystron during an internal arc. A scheme of adding a bypass inductor in the crowbar-protected circuit of the high-power transmitter was tested using computer simulations and actual measurements under a test load. Although this scheme has several benefits, including less power dissipation in the resistor, the tests show that the presence of inductance in the portion of the circuit to be protected severely hampers effective crowbar operation.

  16. Improved transmittance in metal-dielectric metamaterials using diffraction grating

    SciTech Connect

    Sreekanth, K. V. E-mail: gxs284@case.edu; De Luca, A.; Strangi, G. E-mail: gxs284@case.edu

    2014-04-28

    In this Letter, we experimentally demonstrate the possibility to obtain an improved transmittance from metal-dielectric multilayer metamaterials at optical frequencies. In order to achieve this goal, a properly designed one-dimensional silver diffraction grating has been fabricated on top of two different multilayer structures such as Au/Al{sub 2}O{sub 3} and Au/SiO{sub 2}. It has been observed that the improved transmittance at various resonant wavelength bands is possible from the metal-dielectric metamaterials when it is coupled with a properly designed metallic diffraction grating. The obtained results can be expected to find variety of potential applications including high-efficiency solar cells.

  17. Cylindrical PVDF film transmitters and receivers for air ultrasound.

    PubMed

    Toda, Minoru

    2002-05-01

    Cylindrical polyvinylidene fluoride (PVDF) film transducers for transmission and reception of 40-kHz ultrasonic waves in air have been investigated. A key feature of such transducers is their omni-directional polar response. An optimized structure comprises a cylindrical PVDF film element resting on a spool without a mechanical bond to it. Various key design equations to obtain the required ultrasonic performance both as transmitter and receiver are shown, which include resonance frequency, acoustic pressure, angle performance, back air cavity effect, and receiver sensitivity. Measurements of actual frequency response of transmitter output and receiver sensitivity, angular performance, back air space effect, and temperature effect are presented. The results agree well with the theoretical predictions. It has been shown that this device is well-suited for practical application as an ultrasonic ranging device. PMID:12046938

  18. 31. View of mezzanine floor level in transmitter building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    31. View of mezzanine floor level in transmitter building no. 102 showing various electronic central indicator panel to control building air conditioning, steam pressure, supply temperature, discharge temperature, supply pressure, transformer vault status, and radome conditioning system. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  19. 26. View of second floor of transmitter building no. 102 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. View of second floor of transmitter building no. 102 looking across electronic equipment cabinets in area of missile impact predictor (MIP) area. Note U.S. Air Force emblem in mid-center of photograph. This area is in front of the Missile Warning Operations Center (MWOC) office. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  20. Effects of satellite transmitters on captive and wild mallards

    USGS Publications Warehouse

    Kesler, Dylan C.; Raedeke, Andrew H.; Foggia, Jennifer R.; Beatty, William S.; Webb, Elisabeth B.; Humburg, Dale D.; Naylor, Luke W.

    2014-01-01

    Satellite telemetry has become a leading method for studying large-scale movements and survival in birds, yet few have addressed potential effects of the larger and heavier tracking equipment on study subjects. We simultaneously evaluated effects of satellite telemetry equipment on captive and wild mallards (Anas platyrhynchos) to assess impacts on behavior, body mass, and movement. We randomly assigned 55 captive ducks to one of 3 treatment groups, including a standard body harness group, a modified harness group, and a control group. Ducks in the control group were not fitted with equipment, whereas individuals in the other 2 groups were fitted with dummy transmitters attached with a Teflon ribbon harness or with a similar harness constructed of nylon cord. At the conclusion of the 14-week captive study, mean body mass of birds in the control group was 40–105 g (95% CI) greater than birds with standard harnesses, and 28–99 g (95% CI) greater than birds with modified harnesses. Further, results of focal behavior observations indicated ducks with transmitters were less likely to be in water than control birds. We also tested whether movements of wild birds marked with a similar Teflon harness satellite transmitter aligned with population movements reported by on-the-ground observers who indexed local abundances of mid-continent mallards throughout the non-breeding period. Results indicated birds marked with satellite transmitters moved concurrently with the larger unmarked population. Our results have broad implications for field research and suggest that investigators should consider potential for physiological and behavioral effects brought about by tracking equipment. Nonetheless, results from wild ducks indicate satellite telemetry has the potential to provide useful movement data.