Robert T. Menzies
Jet Propulsion Laboratory
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Featured researches published by Robert T. Menzies.
Applied Optics | 1976
Michael S. Shumate; Robert T. Menzies; Jack S. Margolis; L.-G. Rosengren
An optoacoustic detector or spectrophone has been used to perform detailed measurements of the absorptivity of mixtures of water vapor in air. A C(12) O(2)(16) laser was used as the source, and measurements were made. at forty-nine different wavelengths from 9.2 microm to 10.7 microm. The details of the optoacoustic detector and its calibration are presented, along with a discussion of its performance characteristics. The results of the measurements of water vapor absorption show that the continuum absorption in the wavelength range covered is 5-10% lower than previous measurements.
Applied Optics | 1976
Robert T. Menzies; Michael S. Shumate
The ambient air pollutants ozone, nitric oxide, and ethylene have been monitored in the Pasadena area with a bistatic ir laser apparatus. These pollutants were measured with a differential absorption technique using selected wavelengths in the 9.5-microm, 5.2-microm, and 10.5-mum regions, respectively. The transmitted laser radiation was detected using both direct and heterodyne detection techniques. In the direct detection case cube corner retroreflectors provided the return, and the heterodyne detection responded to scattered radiation from various rough surfaces, ranging from 400 m to 1.9 km in distance from the apparatus. Significant departures from ambient background concentration levels were noticed in the region near a local freeway during periods of moderate and heavy traffic.
Applied Optics | 1989
David A. Haner; Robert T. Menzies
Lidar hard target calibration is discussed, emphasizing the transfer target methodology. Characteristics of example calibration target surfaces are described in light of the four reflectance mechanisms: specular, diffuse, retroreflection, and off-specular reflectance. This ideal transfer target is one which can be described as entirely diffusely reflecting, i.e., Lambertian. Correction for retroreflection is required when using the flowers of sulfur transfer target at CO(2) laser wavelengths. Corrections for specular and retroreflection for the integrating sphere are negligible; however, the off-specular reflectance of rough metal surfaces used in the integrating spheres is only qualitatively compared with the diffuse reflectance of flowers of sulfur.
Applied Optics | 1988
Gérard M. Ancellet; Robert T. Menzies; David M. Tratt
We report a series of atmospheric aerosol backscatter measurements at two widely spaced CO(2) laser wavelengths: 9.25 and 10.6 microm. Comparisons are made beween backscatter coefficient profiles at these two wavelengths up to 20-km altitude. Measurements such as those reported here can be used to assess the feasibility of coherent CO(2) lidar for wind measurements, and they also provide a partial test of backscatter model predictions.
Applied Optics | 1988
David M. Tratt; Robert T. Menzies
We investigate the antenna parameters of a coherent lidar in the far-field diffraction-limited regime, where the lidar transmitter consists of an unstable resonator with a Gaussian reflectivity profile output coupler. A figure-of-merit combining laser transmitter energy extraction efficiency with the far-field attributes of a given cavity configuration has been used to compare the lidar performance and relative merits of such systems as they relate to those of conventional unstable cavities with diffractive output coupling.
Applied Optics | 1976
Robert T. Menzies; Michael S. Shumate
Measurements of water vapor absorption were taken with a resonant optoacoustical detector (cylindrical pyrex detector, two BaF2 windows fitted into end plates at slight tilt to suppress Fabry-Perot resonances), for lack of confidence in existing spectral tabular data for the 5-7 micron region, as line shapes in the wing regions of water vapor lines are difficult to characterize. The measurements are required for air pollution studies using a CO laser, to find the differential absorption at the wavelengths in question due to atmospheric constituents other than water vapor. The design and performance of the optoacoustical detector are presented. Effects of absorption by ambient NO are considered, and the fixed-frequency discretely tunable CO laser is found suitable for monitoring urban NO concentrations in a fairly dry climate, using the water vapor absorption data obtained in the study.
Applied Optics | 2017
Upendra N. Singh; Tamer F. Refaat; Syed Ismail; Kenneth J. Davis; S. R. Kawa; Robert T. Menzies; Mulugeta Petros
Sustained high-quality column carbon dioxide (CO2) atmospheric measurements from space are required to improve estimates of regional and continental-scale sources and sinks of CO2. Modeling of a space-based 2 μm, high pulse energy, triple-pulse, direct detection integrated path differential absorption (IPDA) lidar was conducted to demonstrate CO2 measurement capability and to evaluate random and systematic errors. Parameters based on recent technology developments in the 2 μm laser and state-of-the-art HgCdTe (MCT) electron-initiated avalanche photodiode (e-APD) detection system were incorporated in this model. Strong absorption features of CO2 in the 2 μm region, which allows optimum lower tropospheric and near surface measurements, were used to project simultaneous measurements using two independent altitude-dependent weighting functions with the triple-pulse IPDA. Analysis of measurements over a variety of atmospheric and aerosol models using a variety of Earths surface target and aerosol loading conditions were conducted. Water vapor (H2O) influences on CO2 measurements were assessed, including molecular interference, dry-air estimate, and line broadening. Projected performance shows a <0.35 ppm precision and a <0.3 ppm bias in low-tropospheric weighted measurements related to column CO2 optical depth for the space-based IPDA using 10 s signal averaging over the Railroad Valley (RRV) reference surface under clear and thin cloud conditions.
Proceedings of SPIE | 1998
Hamid Hemmati; Carlos Esproles; Robert T. Menzies
A tunable, single-frequency, frequency-stabilized, diode- pumped Tm,Ho:YLF laser is described. The laser, which demonstrates the function of a local-oscillator for coherent Doppler lidar in space, has continuous frequency tunability of more than 8 GHz. Active frequency stabilization is achieved by feedback electronics which allow for controlled tuning capability. Output power of more than 20 mW in single-transverse and -longitudinal mode operation with a short term frequency jitter of less than 100 kHz/ms is obtained.
Optics, Electro-Optics, and Laser Applications in Science and Engineering | 1991
Robert T. Menzies; Madison J. Post
The Global Backscatter Experiment (GLOBE) objectives require intensive study of the global climatology of atmospheric aerosol backscatter at infrared wavelengths. The data obtained from GLOBE are of great importance for analysis of the global winds measurement application of coherent Doppler lidar. Ground-based and airborne backscatter lidars have been developed to measure atmospheric backscatter profiles at CO2 laser wavelengths. Descriptions of the calibration methodologies and selected measurement results are presented.
conference on lasers and electro optics | 2014
Yingxin Bai; Jirong Yu; Teh-Hwa Wong; Songsheng Chen; Mulugeta Petros; Robert T. Menzies; Upendra N. Singh
A single transverse/longitudinal mode, compact Q-switched Ho:YLF laser has been designed and demonstrated for space-borne lidar applications. The pulse energy is between 34-40 mJ for 100-200 Hz operation. The corresponding peak power is >1 MW.