Abstract: An actuator position sensor employs a photo interrupter with an optical density gradient segment that has additional maximum and minimum density segments preceding the gradient segment. These preceding segments are sensed and sampled by a calibration circuit, preferably prior to each operation of the actuator, to generate high and low reference calibration values which are applied to a signal scaling circuit along with the gradient output signal. The scaling circuit is then able to generate a position output signal scaled between these reference values that is linearly proportional to the actuator position.

Abstract: Beam scanning system includes a rotatable element for receiving a stationary light beam at successive element facets to thereby impart a scanning motion to the light beam so as to scan a beam receiving medium. Deviation in the mechanical or optical performance related to each successive facet are corrected by use of a high-speed beam deflector operated in either a closed loop or open loop servo system. The beam deflector includes a unique piezoelectric plate and reflecting body structure, wherein parallel plates of piezoelectric material are bonded at selected locations to a reflecting body with flexible adhesive. The plates are supported by a platform and operatively connected to a plate driving means to effect motion of the body in a push-pull arrangement with respect to the platform. The resulting structure has a high resonant frequency even though a reflecting body in the form of relatively large glass mirror may be employed.