| 摘要 |
PURPOSE:To reduce the measuring region of one optical pickup and to shorten a measuring time, by providing a means for integrally holding a plurality of optical pickups and enabling the same to move by a predetermined interval along a radius direction. CONSTITUTION:Optical pickups 71, 72, 73 are arranged in an optical pickup carrier 7 at an equal interval (d) in a radius direction in a line. When it is assumed that the measuring region of a disc 1 to be measured is shown by a code D when looked in the radius direction, D=3d is formed and (d) comes to an interval equally dividing the measuring length D in the radius direction into three. Each of the optical pickups 71, 72, 73 has the same structure as the optical system of a known optical pickup. When the optical pickup carrier 7 is moved to the outside by the distance (d) along the radius direction, the optical pickups 71, 72, 73 also respectively move by the distance (d) and the measuring region (D in the radius direction) can be entirely detected as a whole.
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