Stationary, electrically alterable, optical masking device and

Abstract

An improved masking device for optical-type radiations (e.g., infrared visible or ultraviolet) is provided and employed in improved optical apparatus, such as spectrometers, requiring alterable radiation masking. The masking device involves no movable parts, is adapted to operate in a fixed position and has radiation transmission and/or reflection characteristics which are selectively alterable merely by controlling electrical excitation applied to the device. The masking device typically has a plurality of separated and predisposedly offset, coplanar zones of solidified, electrooptically active material carried upon a typically transparent substrate and bounded by areas of an opaque material. The active material may be any of the crystalline or polycrystalline materials which have the property of changing their optical characteristic between being relatively transmissive and being relatively reflective and/or opaque for radiations of the wavelengths of interest, in response to alterations in the magnitude of electrical current passing through the material; for example, diachromic compounds such as vanadium dioxide, certain other transition metal compounds and certain organometallic complex compounds. The masking device can be rapidly altered by electrical control to accommodate computerization techniques and Hadamard transforms or analogous mathematical techniques of spectral analysis.