Using a fast lens to collect the signal in a VISAR system
- Sandia National Laboratories, Albuquerque, New Mexico (USA)
VISAR (velocity interferometer system for any reflector) systems are used to measure the Doppler shift of a backscattered laser beam incident on a target, from whence the target's velocity can be calculated. In the past, slow lenses ({ital F}/4 or slower) have been used to collect the scattered light. As a result, the relationship between the velocity and the Doppler shift was precisely known, but in many applications a multiwatt laser was required to give an adequate signal. We are using faster lenses and lower-powered lasers. A faster lens will collect more power and a wider spectrum of Doppler-shifted signal. The average Doppler shift is reduced slightly because of the larger range of signal-collecting angles, but it is essentially a linear function of velocity. The wider Doppler spectrum also reduces the fringe contrast slightly, but it is only significant for very fast lenses and large numbers of fringes.
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6143529
- Journal Information:
- Review of Scientific Instruments; (United States), Vol. 62:12; ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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