| 摘要 |
PROBLEM TO BE SOLVED: To provide a luminous flux dividing element which emits an even number of diffracted rays of light and has enhanced diffraction efficiency. SOLUTION: Many belt-like standard phase patterns P1, P2, etc., which extend in a direction x are formed in parallel on a substrate B at regular pitches in a direction y to obtain the objective luminous flux dividing element 1. The substrate B, including the phase patterns P1, P2, etc., comprises a transparent resin material or a glass material. Each of the phase patterns P1, P2, etc., is formed, in such a way that the phase contrast given in its pitch in the direction y varies nonlinearly. This phase distribution is a composite phase distribution comprising the sum of a 1st phase distribution, in which a phase contact varies in a rectangular wave form with steps of the half-wavelength of incident light and a period T and a duty ratio of 1 are ensured, and a 2nd phase distribution, in which a phase contrast varies nonlinearly and a period is T/2.
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