| 摘要 |
PURPOSE:To obtain a device which is small-sized and inexpensive, by driving a glass plate which has recorded a hologram as an optical deflector, by a DC motor, and also controlling a rotating speed of the motor by detecting a mark of the glass plate. CONSTITUTION:On a glass disk 12, holograms 131-13n are recorded at constant intervals on its outside circumference, and on the inside circumference, a mark 14 for detecting its rotation is recorded at constant intervals. A laser beam emitted from a laser 13 passes through a half-mirror 16 and a lens 17, is modulated by an information signal by an optical modulator 18, and is made incident to the hologram 13i on the glass disk 12 through a lens 28. When the glass disk 12 is rotated by a DC motor 19 and the hologram 13i is moved, the laser beam is deflected, and write is executed on a recording body 20. On the other hand, the light beam which has been made to branch by the half-mirror 16 passes through the part of the mark 14, is made incident to a photodetector 22, and by its output, the motor 19 is controlled to a constant speed. Accordingly, a device which is small-sized and inexpensive is obtained. |
