Adjustable bandpass filter employing a prism.
A system employing a prism has been developed and used as a variable, wide bandpass filter for the visible and near ir. The bandpass is determined by adjusting a pair of slits placed in the focal plane of the system. Mirrors near the focal plane displace the beam and direct it back through the prism, and an undispersed image of the entrance slit is formed for all wavelengths within the bandpass. When used to prevent overlapping orders in a grating spectrometer, the system has several advantages over conventional prism systems used for this purpose.
Burch
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