Spectrally Selective Shutter Mechanism

Several state-of-the-art detection and image systems require synchronous high-speed shuttering of incoming irradiance. This shuttering action is necessary in many instances to increase signal-to-noise ratio, obtain high-speed (low-retention) imagery, and provide single-event observations. Presently, this type of snap-shot imagery is approximated by rotating chopper wheel methods that sweep an aperture across the focal plane. At faster aperture rates, these mechanical chopper systems become more complex and maintenance of image fidelity is very difficult. This novel, spectrally selective shutter mechanism provides true snap-shot imagery. Despite some limitations, such a mechanism is ideally suited to high flux, high background, and rapidly changing imaging visualization, and can be used to monitor flow visualization, chemiluminescence phenomena, and laser operation. The optomechanical technique described in this report uses the rotation of one or two narrowband spectral filters to provide open-shutter times in the millisecond range. The resulting performance of the two-filter assembly is governed by the physical principle that increasing angular tilt of a narrowband interference filter that causes the bandpass parameter to shift progressively toward shorter wavelengths. Keywords: infrared filters.