To solve the problem that it is difficult to make high resolution due to the limit of refining a code pattern or the like on a code plate.
The optical encoder consists of a light source part, a light receiving part, and the movable code plate 4 located between the optical paths of both the parts, in which the well known pattern for detecting an absolute position to detect the information of the absolute position of the code plate 4 is formed on an outside track T2 on the code plate 4, and a phase type diffraction grating is formed on an inside track T1. Then the relative position information of the code plate 4 is detected based on the interference beam of two diffraction beams diffracted with the phase type diffraction grating and therefore detection with high resolution can be done from the combination of both the information.
SAKAMOTO MASAHIKO
OBARA TAKAO
NAKAJIMA HAJIME
SAKUMA HIROKAZU
OKAMURO TAKASHI
AOKI YUKIO
OKA TORU
OMURA YOICHI
