Abstract: A day/night vehicle rearview mirror assembly comprises a casing carrying a prismatic mirror, the casing being pivotally mounted on a mounting plate. Preferably, the casing and mirror are driven between a full reflectance position and partial reflectance position by a rack and pinion assembly having interengaging gear teeth extending between a d.c. motor operated drive shaft and a portion of the casing. Alternately, a friction coupling extends between the drive shaft and casing. A noise and vibration reducing coupling are provided in the drive shaft while appropriate glare sensing circuitry and/or switches control operation of the reversible motor and, thus, the reflectance position of the mirror.

Abstract: Achromatic optical systems forming phase shifters and phase modulators are presented and shown to impart (temporal) phase-angle shifts in incoming waves which are independent of wavelength over extremely broad spectral ranges (achromatic or white light). Three major classes of achromatic phase shifters are described including the triangle, close cascade, and imaged grating configurations. When constructed utilizing volume holographic optical elements, very high diffraction efficiencies may be achieved over the large bandwidths used. These systems may similarly be utilized to impart achromatic frequency shifts and frequency modulations which are wavelength independent over extreme spectral ranges and usually do not disturb the spatial form of the input waves. These devices may be used in AC interferometers and allow such interferometers to be operated with white light. The devices are also useful in switching between spatial sine and cosine optical transforms in optical pattern recognition systems.