Accession Number : ADA302218

Title :   Techniques of Single-shot Thermometry by Degenerate Four-wave Mixing.

Descriptive Note : Technical rept.,

Corporate Author : CALIFORNIA INST OF TECH PASADENA GRADUATE AERONAUTICAL LABS

Personal Author(s) : Cummings, Eric

PDF Url : ADA302218

Report Date : AUG 1994

Pagination or Media Count : 42

Abstract : A summary of single shot techniques of thermometry by degenerate four wave mixing was presented in this paper. Thermometry by making population measurements via multishot laser scanning is impractical in many pulsed or short duration facilities. Conventional single shot DFWM techniques suffer from a variety of problems, including thermal grating interferences and complicated signal analysis. Au unconventional single shot FWM technique was discussed and analyzed using the linearized equations of hydrodynamics and light scattering. In this technique the signal beam scattered off laser induced (thermal) acoustic gratings is time resolved revealing information about the evolution of the gratings. The thermal diffusivity, acoustic damping coefficient, and sound speed (thereby temperature) are readily extracted from an analysis of the signals. The merits and limitations of both techniques were discussed.

Descriptors :   *FOUR WAVE MIXING, *ACOUSTOOPTICS, *THERMOMETERS, LIGHT SCATTERING, SHORT RANGE(TIME), GRATINGS(SPECTRA), LASER APPLICATIONS, COEFFICIENTS, LIGHT PULSES, ACOUSTIC MEASUREMENT, QUANTUM ELECTRONICS, DIFFUSIVITY, ACOUSTIC VELOCITY, OPTICAL SCANNING.

Subject Categories : Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE