Abstract
This paper describes on a new method of the positioning with five adjacent lines in a linear scale and its experiment and result by using the new designed photoelectric microscope in order to reduce the errors of line positions in a scale and to use in higher accuracy. The microscope which has a mask with five slits arranged in equal interval at the image plane of the objective carries out the way above optically. As the result of experiment, the short period error and the random error in the scale are reduced and the special large errors are excluded, then the accuracy of the scale can be improved both to 1μm from 5μm level by using this method and from 20 μm level by using together with the existing automatic compensational way for scale errors.
