Reflectance and relative transmittance of laser-deposited iridium in the vacuum ultraviolet.
Evaporation of thin films of high melting point materials by focused laser beam and reflectance and relative transmittance in vacuum UV
LASER OUTPUT↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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An excitation mechanism for the A super plus laser.
Direct excitation in argon gas from metastable state to upper laser state compared with two-step excitation
METASTABLE ATOM↗
Continuous wave laser ground-to-space-to- ground laser experiment.
Continuous wave laser ground-space-ground experiment in conjunction with Explorer XXII SATELLITE tracking
SATELLITE TRACKING↗
Absolute frequency stabilization of a laser oscillator against a laser amplifier.
Frequency stabilization of laser oscillator against reference laser amplifier, noting residual AM effects
FREQUENCY STABILITY↗
Fluorescent photography of droplets in a spray using a Q-switched laser as a light source.
Q-switched laser use as light source for photographing droplets in spray containing fluorescent dye excited by second harmonic of ruby light
LASER OUTPUT↗
Observed laser lines in freon-helium mixtures.
Laser lines observation in Freon-He mixtures in CW gas discharge
CONTINUOUS WAVE↗
Holographic interferometry with ultraviolet light.
Holographic interferometry with UV light from KDP crystal generating second harmonic of Q switched ruby laser red output, noting optical path length sensitivity
Briones, R. A.↗
Visible CW parametric oscillator.
Tunable optical parametric oscillator using argon laser CW output as pump and lithium niobate as nonlinear crystal
Byer, R. L.↗
Fluid mixing technique increases the gain and output power of carbon dioxide laser systems
High speed flowing gas system provides uniform mixing in short times compared to flow transit times and carbon dioxide vibrational relaxation times. This system minimizes the effects of surrounding surfaces and provides a uniformly high gain that is independent of dimensions transverse to the flow direction.
Cool, T. A.↗
An optical radar for airborne use over natural waters
An optical radar for detecting targets in natural waters was built and tested in the Gulf of Mexico. The transmitter consists of a Q switched neodymium glass laser, with output amplified and doubled in KDP to 0.53 micrometer wavelength. The receiver incorporates a noval optical spatial filter to reduce the dynamic range required of the photodetector to a reasonable value. Detection of targets to a depth of 26 meters (84 feet) was achieved with a considerable sensitivity margin. The sensitivity of the radar is highly dependent on the optical attenuation coefficient. In general, measured returns fell between the values predicted on the basis of monopath and multipath attenuation. By means of simple physical arguments, a radar equation for the system was derived. To validate this theoretical model, measurements of optical attenuation and of water surface behavior were also instrumented, and some of these results are given.
Levis, C. A.↗
Lidar temperature profiling: Performance simulations of Masons method
Several methods of using lasers to measure atmospheric temperature profiles were described. Mason's suggestion was analyzed here to assess its capabilities for various lidar configurations. Temperatures were inferred from a measure of the Boltzmann distribution of rotational states in one of the vibrational bands of O2. Differential absorption was measured using three tunable, narrowband pulsed lasers. The outputs of two were tuned to wavelengths at the centers of absorption lines at either end of a particular branch in the band. The third wave-length was in a region of no absorption; its lidar return measured only the atmospheric backscatter, and therefore allowed calculations of the absorption coefficients at the other two wavelengths as a function of altitude. From the ratio of the two line absorption coefficients plus a priori knowledge of the line parameters, the temperature-altitude profile were calculated.
Schwemmer, G. K.↗
Lidar temperature profiling - Performance simulations of Mason's method
In Mason's method (1975) atmospheric temperatures are inferred from a measure of the Boltzmann distribution of rotational states in one of the vibrational bands of O2. Differential absorption is measured using three tunable, narrowband pulse lasers. The outputs of two are tuned to wavelengths at the centers of absorption lines at either end of a particular branch in the band; the third wavelength is in a region of no absorption. The temperature-altitude profile can be calculated from the ratio of the two line absorption coefficients plus a priori knowledge of the line parameters. In the present paper, computer simulations of various lidar configurations are made, using different line pairs in the atmospheric bands of O2 (approximately 630, 690, and 760 nm). Simulated results are presented for temperature profiles measured from a Space Shuttle lidar.
Schwemmer, G. K.↗
Density measurement in air with a saturable absorbing seed gas
A method for making density measurements in a compressible flow by using off resonance laser induced fluorescence is studied. The seed molecule chosen for study is the iodine molecule which is excited with the 514.5 nm line of the argon ion laser whose output is frequency tuned, by as much as 3 GHz, relative to a strong iodine transition using an intracavity etalon. The theory which was developed to analyze the effect will be used in conjunction with two experiments being conducted to further study the method an acoustic resonance tube in which controlled perturbations about a uniform state are produced, and a small supersonic jet in which the conditions of the flow vary widely from point to point.
Baganoff, D.↗
Low temperature operation of an S2 laser using radio frequency simmer discharges
Technological problems stemming from high temperature operation of the sulfur resonator have hindered its development as a tunable, efficient, discharge pumped laser. The use of RF simmer discharges is shown to reduce previous temperature constraints by dissociating polyatomic sulfur molecules into the dimer, such that lasing is achieved when pumped by an XeCl excimer laser. The peak power output of the S2 laser and the transmission spectra through sulfur discharges are used to infer the effectiveness of the discharge in dissociating the vapor.
Killeen, K. P.↗
An advanced solid state pressure transducer for high reliability SSME application
New methods to advance the state-of-the-art of pressure sensors for the Space Shuttle Main Engine were demonstrated. The results of the feasibility and breadboard demonstration phase and the current status of the research development prototype follow-on phase are presented. A technology breakthrough utilizing silicon piezoresistive technology was achieved in the first phase. A transducer design concept for the SSME application utilizes packaging materials with similar thermal coefficients of expansion and maintains the transducer seals primarily in compression. The silicon chip design will provide dual sensing outputs with laser trimmable integrated compensating electronics. The silicon resistor ion implant dose was customized for the SSME temperature requirement. A basic acoustic modeling software program was developed to evaluate the frequency response characteristics for the package design.
Johnson, R. L.↗
Efficient, frequency-stable laser-diode-pumped Nd:YAG laser
One of the main goals of the study was to demonstrate a low-power efficient Nd:YAG laser oscillator for applications in remote coherent Doppler anemometry. An electrical-to-optical slope efficiency of 6.5 percent has been achieved by using commercially available CW laser diodes of up to 100 mW to pump monolithic Nd:YAG rod lasers. The observed Nd:YAG oscillation threshold is at 2.3 mW of laser-diode output power, i.e., a small fraction of the rated output power. The highest Nd:YAG CW output power reached is 4.4 mW at an overall electrical-to-optical efficiency of 1.5 percent. The frequency jitter is less than 10 kHz in 0.3 s.
Zhou, B.↗
Single-ended output GaAs/AlGaAs single quantum well laser with a dry-etched corner reflector
GaAs/AlGaAs single quantum well lasers with integrated corner reflectors have been fabricated using chemically assisted ion beam etching. The air-GaAs interface is internally totally reflecting, and no coherent radiation is transmitted through the corner reflector. The corner reflector laser was compared with a conventional Fabry-Perot laser cleaved from the same wafer. An 11-percent reduction in threshold current and a reduction of the far-field angle from 4.4 deg to 0.7 deg was measured.
Hagberg, M.↗
Solid-state lasers for coherent communication and remote sensing
Semiconductor-diode laser-pumped solid-state lasers have properties that are superior to other lasers for the applications of coherent communication and remote sensing. These properties include efficiency, reliability, stability, and capability to be scaled to higher powers. We have demonstrated that an optical phase-locked loop can be used to lock the frequency of two diode-pumped 1.06 micron Nd:YAG lasers to levels required for coherent communication. Monolithic nonplanar ring oscillators constructed from solid pieces of the laser material provide better than 10 kHz frequency stability over 0.1 sec intervals. We have used active feedback stabilization of the cavity length of these lasers to demonstrate 0.3 Hz frequency stabilization relative to a reference cavity. We have performed experiments and analysis to show that optical parametric oscillators (OPO's) reproduce the frequency stability of the pump laser in outputs that can be tuned to arbitrary wavelengths. Another measurement performed in this program has demonstrated the sub-shot-noise character of correlations of the fluctuations in the twin output of OPO's. Measurements of nonlinear optical coefficients by phase-matched second harmonic generation are helping to resolve inconsistency in these important parameters.
Byer, Robert L.↗