| 摘要 |
A holographic information recording/reproducing apparatus and a method for searching book position in the same are provided to calculate positions of books which are two dimensional areas, using optical detectors around an iris, in order to measure an error in book position. A holographic information recording/reproducing apparatus comprises an iris(20), optical detectors(22,23,24,25), and a book position calculating part. The iris is located on the optical path of projected signal beam and is formed with an opening(21) to limit the width of the signal beam. The optical detectors are installed on the surface of the iris along the periphery of the opening. The book position calculating part calculates the positions of books which are two-dimensional areas. A sectional area of reference light projected to the holographic recording medium is larger than the one book. The optical detector is divided into two segments. The book position calculating part calculates the book position error from the difference between measurements by the two segments.
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