| 摘要 |
<p>An interval of incident places of -1st diffraction light, 0-th light, and +1st<SUP/>diffraction light is set to be three times (3p) a bit pattern pitch of a track (31). The incident place of the 0-th light and the ±1st diffraction light become to vibrate in an X-axis direction by a rotating vibration of a vibrating mirror (14) by a driving device while the interval of the incident place is maintained with each other. An amplitude (half amplitude) of the vibration is set to be equal to a pitch (p) of the bit pattern. The incident places of the 0-th light and ±1st diffraction light move between regions corresponding to three bits with an equal interval, respectively. Thus, 9-bit absolute position information can be read out by using three diffracting light.</p> |
