| 摘要 |
PURPOSE:To eliminate the distortion of patterns or the like owing to the unevenness in scanning speed and to obtain good patterns by controlling the scanning speed by the use of the monitor scanning light separated from record- and read scanning light. CONSTITUTION:The beam from a laser LSR modulated with a signal source MS is bent by a mirror MR, transmits through a rotary glass cylinder GSD and a half mirror HM, and is diffracted by a hologram disc HGD. The monitor scanning light MNL consisting of the transmitted primary diffraction light by the segment C1 having a diffraction characteristic differing from those of the other segments C2-Cn for recording and reading scans on the equally spaced pattern of a reflection type bar scale. The reflected light thereof enters a detector DET via the half mirror HM, by the output whereof the signal source MS is controlled. Thereby, the distortion of the patterns or the like owing to the unevenness in scanning speed is eliminated and the good patterns or the like are obtained. |
