To provide a wavelength variable filter, more simply variably controlling the transmission wavelength with high accuracy, concerning light of a wide wavelength region including short wavelength region from an ultraviolet region to blue.
In the wavelength variable filter 31, Babinet-Soleil phase plates 33a-33c, which are birefringent elements including wedge-like birefringent plates 34a1-34c1, 34a2-34c2 with the same wedge angle 1-3, respectively, are disposed along the optical axis 4 between a plurality of polarizers 32a-32d. The respective Babinet-Soleil phase plates are adapted to vary the thickness D1-D3 by displacing one birefringent plate in the direction perpendicular to the optical axis for the same displacement, thereby correcting the phase difference of light transmitted through the respective Babinet-Soleil phase plates to satisfy the expression: 2i-12+k2, (i=1 to 3, k: non-negative integer), so that the wavelength variable filter is changed to a desired transmission wavelength.
| JP3348257 | OPTICAL ISOLATOR |
| WO/1997/007425 | POLARIZATION-INDEPENDENT OPTICAL ISOLATOR |
| JPH07508348 | [Title of Invention] Three-dimensional block homodyne interferometer |
Masahiko Ueyanagi
Osamu Suzawa
Kazuhiko Miyasaka
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