| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a variable filter device for efficiently shielding a specified wavelength of light. Ž<P>SOLUTION: Divergent light passing through an incident pinhole plate 2 is converted into collimated-light flux by a collimating lens 3, and made incident on an acousto-optical variable filter 4. The acousto-optical variable filter 4 is applied with a prescribed frequency of voltage to serve as a diffraction grating, diffraction light is emitted diagonally to an optical axis as shown by a dotted line, only zeroth-order light travels straight. The light flux emitted from the acousto-optical variable filter 4 is condensed by a condensing lens 5, in this case, the straight zeroth-order light passes through a pinhole of an emission pinhole plate 6, and is emitted toward the outside of the variable filter device 1. The diffraction light collides with a plate part of the emission pinhole plate 6 to be shielded, and is not emitted toward the outside of the variable filter device 1. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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