| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable filter device for shielding efficiently a specified wavelength of light. SOLUTION: A divergent beam passing through an incident pinhole plate 2 is converted into a parallel beam by a collimating lens 3, and enters 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, a diffraction light is emitted diagonally to an optical axis as shown by a dotted line, and only a zeroth order light travels straight. The light beam emitted from the acousto-optical variable filter 4 is converged by a convergence lens 5, and the 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. COPYRIGHT: (C)2009,JPO&INPIT
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