| 摘要 |
<p>A method of photoelectrically reading information recorded in the form of a Fresnel hologram (2), which makes it possible to eliminate the effect on the reading accuracy of a scratch, a stain, etc., on the hologram surface when the recorded information is reconstructed by applying a light beam having a small diameter to the hologram. The surface of the hologram (2) is illuminated by scanning it with a light beam (3) having a cross-section smaller than the hologram recording region, thereby reconstructing and reading the same recorded information separately from different hologram regions, and thus compensating for momentary disability to reconstruct the recorded information due to a scratch or stain. At the same time, since a light beam having a small beam diameter is used for reconstruction, the depth of focus of the reconstructed image increases, so that the number of restrictions on the installation position of the read sensor decreases. <IMAGE></p> |
