| 摘要 |
PURPOSE:To reduce the pinch error of a projected beam spot by positioning a spindle, which rotates and drives a disc, to a certain position. CONSTITUTION:The laser beam from a laser oscillator 5 is divided into two laser beams 8 and 9 by a beam splitter 6, and one laser beam 8 is modulated in an optical modulator 10 by a tracking signal, and the other laser beam 9 is modulated in an optical modulator 11 by an address signal. Laser beams 12 and 13 modulated by optical modulators 10 and 11 are synthesized by a synthesizing beam splitter 16 and are projected onto a master disc 4 through an objective lens 18. Since two laser beams 12 and 13 incident on the objective lens 18 from an angle by a reflecting mirror 17, two beam spots 20 and 21 are shifted in the radial direction of the disc original board 4 and are projected there. Consequently, a moving table 3 is moved in the radial direction of the original board 4 in accordance with rotation driving of the master disc 4 to expose double the original board 4 spirally. |
