| 摘要 |
PURPOSE:To improve the S/N of light information by separating reflected laser light from an acoustooptic element from modulating light even directionally if the laser light is transmitted through the acoustooptic element again when the 1-order diffracted light of the acoustooptic element is deflected, scanned, and recorded as modulating light. CONSTITUTION:The incidence surface 30 and projection surface 31 of the ultrasonic wave propagation medium 3B of the acoustooptic element AOM are slanted at a Bragg angle thetaB to an ultrasonic ave propagation direction Z in the same direction. Laser light L should be incident on the incidence surface 30 orthogonally so as to satisfy the Bragg condition; reflected laser light and reincidence light are both completely coaxial with the laser light L and transmitted laser light is coaxial with 0-order light. Then, the transmitted laser light and 1-order modulating light are separated sufficiently and the transmitted laser lighjt is absorbed by a stopper together with the 0-order modulating light. Therefore, the transmitted laser light and 1-order modulating light are separated sufficiently from each other even when the incidence and projection surface are slanted at the Bragg angle in the opposite directions. |
