Abstract: An optical focus sensing system is disclosed. The system provides a focus shift measurement capability utilizing the relative motion between two gratings to produce different diffraction orders which are separately detected by a pair of detectors to form signals having a phase difference proportional to the focus error corresponding to the planes occupied by the two gratings. A control circuit is responsive to the phase difference between the signals from the two detectors to provide a controllable focusing capability.

Abstract: A light beam scanning apparatus is constituted for scanning a light beam deflected by a rotating polygon mirror on a scanning surface in a main scanning direction, moving the scanning surface with respect to the light beam in a subscanning direction, and generating a picture element clock signal. The light beam scanning apparatus comprises photodetectors for respectively detecting passage of the light beam over a main scanning start point and passage thereof over a main scanning end point, and a clock signal generating circuit for receiving outputs of the photodetectors, calculating the time required for the main scanning for each of the mirror surfaces of the rotating polygon mirror, and changing a period of the picture element clock signal in the course of each main scanning so that the period is proportional to the required time with respect to the mirror surface utilized for the main scanning.

Abstract: An apparatus for scanning a sheet of printed material including a top frame element having a rail thereon for guiding the movement of a hand held optical character reader. A sheet of paper is inserted between a top frame element and a bottom frame element which is spaced therefrom. A window having tapered edges is provided in the top frame element through which an operator can insert a finger or thumb to advance the paper in a path transverse to the direction of movement of the optical character reader. In this way, the path of traverse of the optical character reader will not become misaligned with the printed lines on the sheet.

Abstract: A drift free magneto-optic current transformer for measuring an electric current which may include a d-c component in which two orthogonally polarized light beams are passed through a magneto-optic element operating as a Faraday rotator to rotate the beams through an angle dependent upon the magnitude of the d-c current. An analyzer, oriented with two orthogonal polarization axes set at +45 degrees and -45 degrees with respect to the plane of polarization of the first input light beam and at -45 degrees and +45 degrees with respect to the plane of polarization of the second input light beam, splits each emerging light beam into two output light beams which are converted into a.sub.1 and b.sub.1, and a.sub.2 and b.sub.2 electrical signals in response to the first and second input light beams respectively. By maintaining the signal (a+b).sub.1 equal to (a+b).sub.2, and by maintaining (a-b).sub.1 +(a-b).sub.2 equal to zero, an output signal (a-b).sub.1 -(a-b).sub.

Abstract: A multipixel light sensing semiconductor device contains in at least one pixel a lens presenting a convex surface and a lens supporting layer for directing light inwardly to a semiconductive light sensor. The lens supporting layer has a thickness exceeding that of the lens, and the lens is laterally confined on the lens supporting layer between at least two opposed pixel edges.