Accession Number : ADA088842


Title :   Evaluation of Specialized Photoacoustic Absorption Chambers for Near-Millimeter Wave (NMMW) Propagation Measurements.


Descriptive Note : Technical rept.,


Corporate Author : ARMY ELECTRONICS RESEARCH AND DEVELOPMENT COMMAND WSMR NM ATMOSPHERIC SCIENCES LAB


Personal Author(s) : Sojka,Brian Z ; White,Kenneth O


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a088842.pdf


Report Date : Aug 1980


Pagination or Media Count : 38


Abstract : Preliminary studies have been conducted to determine the feasibility of using spherical geometry photoacoustic absorption chambers at near millimeter wavelengths (NMMW). New spherical geometry photoacoustic absorption chambers were used in a parallel experimental arrangement to the ongoing (FY 79) NMMW program. Absorption sensitivity, NMMW laser beam handling characteristics, pressure dependence, and temperature effects of the system were evaluated to determine the usefulness and applicability of these new designs for use at NMMW. Electret microphones were acquired, and testing was done by using these microphones as detectors in specialized spherical geometry and more conventional design photoacoustic absorption chambers. Results from this study show that numerous problems exist in using the sperical geometry photoacoustic absorption chamber design. The combination or resonant frequency temperature dependence, unstable mechanical chopping, high-Q narrow-bandwidth characteristics, and excessive noise sensitivities have limited the absorption sensitivities obtainable. Electret microphone testing and evaluation have led to the design and construction of several conventional, single-pass type, photoacoustic absorption chambers. (Author)


Descriptors :   *MILLIMETER WAVES , *RADIATION ABSORPTION , *ACOUSTOOPTICS , LASER CAVITIES , OPTICAL WAVEGUIDES , ABSORPTION SPECTRA , SPECTRAL LINES , ELECTRETS , SPECTROPHONES


Subject Categories : Acoustic Detection and Detectors
      Optics


Distribution Statement : APPROVED FOR PUBLIC RELEASE