Abstract
In this study, an optical absolute encoder with a 3-tone reflective scale has been proposed. The 3-tone scale provides more information, compared to conventional absolute scales. Thus, the increase of information density by 3-tone scale contributes to the miniaturization of sensors and rough alignment of the encoder. We have developed a compact sensor and 3-tone reflective scales by MEMS technology. The sensor consists of VCSEL (Vertical-Cavity Surface-Emitting Laser) and PD (Photo Diode) chips. Also, the 3-tone scales have Au total mirrors and Cr half mirrors which are patterned on a glass substrate. With our developed sensor and scales, the applicability of an absolute encoder has been demonstrated. It is expected that this device could be applied to compact absolute encoders for robotics and mechatronics applications.
