| 摘要 |
PURPOSE:To facilitate easy generation of the titled hologram with a high diffraction efficiency by sticking two pieces of linear diffraction gratings of unequal pitches having light transmissivity so that each grating direction becomes orthogonal and each grating formed surface is opposed. CONSTITUTION:A hologram 10 and a hologram 11 are formed by a light transmissive material and are saw tooth linear diffraction gratings whose one side surface is an unequal pitch. By sticking the diffraction grating formed surfaces so that the surfaces on which the diffraction gratings have been formed, of these hologram 10 and hologram 11 are opposed to each other, and also, the directions of the diffraction grating are orthogonal to each other, an optical scanning hologram is formed. This optical scanning hologram is rotated around a suitable axis vertical to the optical scanning hologram surface, and a light beam from a light source fixed in a space is radiated as a suitable divergent light, by which a diffracted light whose scanning beam diameter is small, for executing a linear scan is obtained. In such a way, the generation is facilitated, and also, a high diffraction efficiency is obtained.
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