| 摘要 |
PURPOSE:Not only to read the information exactly but also to make the unit small- sized by shortening the light passage length, by forming the optical information reader so that the interference effect due to returning beam can be suppressed effectively. CONSTITUTION:The radiating beam from the rear end of the semiconductor laser 1 is rotated in the polarized direction by 45 deg. by the 1/2 wavelength plate 11, furthermore is rotated by 45 deg. by the Faraday element 10, intersects at right angles with the polarized direction of the reflecting beam from the information recording carrier, and is incident to the polarization splitter in the polarized direction. Therefore, the radiating beam from the rear end of the laser gets out of the feedback light passage as shown by a broken line. Accordingly, since the feedback light passage does not form the external resonator but operates as a kind of link laser, no standing wave of a light beam exists in the feedback light passage, and the output fluctuation due to the interference effect is removed. As mentioned above, since not only the information can be read exactly but also the light passage length can be shortened, the unit can be made small-sized. |
