Fabry-Perot velocity interferometer

The advent of lasers allowed optical interferometry to become a useful and accurate technique to determine surface motion in shocked materials. The two most commonly used interferometric systems are the VISAR (Barker and Hollenbach, 1972) and the Fabry-Perot velocity interferometer (Johnson and Burgess, 1968 Durand et al., 1977). Both systems produce interference fringe shifts which are proportional to the Doppler shift of the laser light reflected from the moving specimen surface. Both can accommodate a speci-... 

Durand, M. (1984), Use of Optical Fibers for Velocity Measurement by Laser Doppler Interferometry with a Fabry-Perot Interferometer. In High Speed Photography and Photonics, Proc. SPIE, 491 (edited by M. Andre and M. Hugenschmidt), pp. 650-656. 

Bundy et al (Ref 13) measured the velocity and pressure of gases in a rocket flame by determining the small shift in wavelengths of the flame luminosity with a Fabry-Perot interferometer... 

There are several types of velocity interferometers, such as ORVIS, FABRY-PEROT, VISAR, and others. They differ from each other in time resolution that is, from about 0.3 nanoseconds to a few nanoseconds. 

Determination of the velocity of a metal shim moved the explosive charge detonation using the Fabry-Perot interferometer is illustrated in Figure 4.68. 

When the target velocity is to be determined, the laser beam is sent to the moving target. The target surface is prepared to produce a diffuse reflected beam. Mirrors and lenses are used to direct the reflected beam as a parallel one to the Fabry-Perot interferometer. 

Fig. 5. Polarized Rayleigh-Brillouin spectrum of amorphous PnHMA taken with a Burleigh plane Fabry-Perot interferometer using a free spectral range of 12.4 GHz at 295 K. The two Brillouin peaks are shifted from the incident frequency by the product of the wave vector q and the sound velocity u. The line width of the Brillouin peaks is related to the attenuation of the sound waves. PnHMA.

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