Abstract: A laser length measuring instrument in which a first and a second sinusoidal wave interference signals differing in phase by .pi./2 are generated from a plurality of interference wave signals received from an interferometer; a plurality of third sinusoidal wave interference signals differing in phase by m.pi./2 n (where n=integer 2 or greater; m=positive integer sequentially selected from among 0<m.pi./2n<.pi.

Abstract: A pattern defect inspection apparatus detects presence or absence of a defect in a pattern formed on a semiconductor wafer by scanning the pattern normally to the surface thereof by a coherent light beam of a predetermined spot size, detecting reflected diffraction lights generated thereby and processing the detected lights. It comprises an abnormal direction signal detector including photo-detectors having wide light receiving areas arranged in a plurality of spatial areas which the reflected diffraction lights from a normal pattern do not normally reach, a normal pattern detector including photo-detectors having large light receiving areas arranged in a plurality of spatial areas which the reflected diffraction lights from the normal pattern reach, and a defect discriminator for determining if the abnormal direction signals are due to a true defect or not in accordance with the signals from the abnormal direction signal detector and the normal pattern detector.

Abstract: In a small particle detection system for use in detecting small particles, which float in a gas, by utilizing the light scattering effect thereof, a detecting cell is disposed in an external optical resonator which is adapted to resonate with the output light from a laser oscillator. When the detecting cell is disposed in the laser oscillating optical resonator, the position is selectively determined; the former is set in the position in the latter in which the diameter of a laser beam is minimal.

Abstract: A light beam scanning apparatus projects a light beam swept by a light scanner to a spherical mirror and scans by a light beam spot reflected and focused by the spherical mirror a surface of an object arranged to oppose to the spherical mirror at a position spaced from the spherical mirror by a distance equal to a focal distance f of the spherical mirror. An optical path length between the light scanner and the spherical mirror is set to 0.78 f-0.84 f to minimize a curvature of field (circle of confusion).

Abstract: In forming a film of a purposive substance on a substrate by a chemical vapor deposition (CVD), the size of the film-forming substance particles formed in a reactor is detected as an electrical signal and flow rates of respective gases introduced into the reactor are controlled in response to this electrical signal. According to this control method, the fogging phenomenon owing to formation of the film-forming substance in the gas flow can be effectively prevented.