title: Real-time velocity measurement by the use of a speckle-pattern correlation system that incorporates a ferroelectric liquid-crystal spatial light modulator.
abstract: We describe a technique for noncontact velocity measurement by using double-exposure speckle-pattern techniques with optical signal processing. The two speckle patterns are recorded on a ferroelectric liquid-crystal (FLC) spatial light modulator (SLM), which is a bistable optically addressed SLM, and the composite pattern is then analyzed by an optical system similar to a joint transform correlator, in which another FLC-SLM and a position-sensitive detector are used. We show that the performance of the system can be significantly improved by adjusting the time between exposures using a real-time feedback system that is based on the position of the correlation spot in the output plane.
authors.forename: Y
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: T
authors.initials: T
authors.lastname: Takemori
authors.forename: N
authors.initials: N
authors.lastname: Mukohzaka
authors.forename: N
authors.initials: N
authors.lastname: Yoshida
authors.forename: S
authors.initials: S
authors.lastname: Fukushima