JPS6412212A - Microangle displacement measuring apparatus - Google Patents

Abstract

PURPOSE:To achieve a higher accuracy, by providing two photoelectric conversion means to calculate a difference between corresponding detection values. CONSTITUTION:Light beam from a light source is separated with a beam splitter and reflected light beams 23-1 and 23-2 made incident into a surface 21 to be inspected dislocated by an angle theta from a reference bearing and an irradiation receiving surface 22 fixed on a support the same as the surface 21 are detected with angle displacement sensors 24-1 and 24-2 as photoelectric conversion means at equal distances from these surfaces. The sensors output signals X1 and Y1 and X2 and Y2 corresponding to light receiving positions of the reflected light beams on light receiving surfaces for detection. An output of the sensor 24-1 contains a component corresponding to fluctuation of the reflected light beams caused by variation in surface azimuth and disturbance of air due to a surface tilt angle and mechanical vibration of the surface 21 while an output of the sensor 24-2 does not contain a component attributed to the surface tilt angle. Outputs of the sensors are inputted into differentiators 25-1 and 25-2 to calculate a difference between output values of X and Y coordinate eliminating effect of fluctuation, thereby achieving a higher measuring accuracy.