| 摘要 |
PROBLEM TO BE SOLVED: To overcome the problem relating to limitation of incident angles of incident light which is the drawback of a plate polarization beam splitter of a conventional structure having a polarization beam splitter film with uniform thickness on a transparent plate, and to provide a polarization beam splitter which can be used for not only parallel light but diverging light and converging light. SOLUTION: In the plate type polarization beam splitter having a polarization beam splitter film 3 deposited on a transparent plate 2, the polarization beam splitter film is structured so that its film thickness gradually increases in one direction in such a manner that the film has different optimum film thickness according to the incident positions of the incident light beams with different incident angles and incident positions.
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