| 摘要 |
PURPOSE:To eliminate the occurrence of interference fringes and, at the same time, to prevent the titled image reader from becoming complicated and expensive, by providing an optical element which constitutes a laser beam of a luminous flux having a random phase difference. CONSTITUTION:To an image reader which scans a medium 28, on which an image is recorded, with a laser beam condensed on one spot and reads the image from transmitted or reflected light from the medium, an optical element 29 which constitutes the laser beam of a luminous flux having a random phase difference is installed. Namely, the random phase difference is given to the laser beam and the laser beam is made incident on the surface of the medium as a spot. Therefore, the spot light is constituted of light having random phases, which are directly transmitted through the medium and reflected inside the medium and overlapped upon each other. As a result, the fluctuation of the intensity of the spot light caused by variation of phase difference can be suppressed and the occurrence of interference fringes can be eliminated.
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