| 摘要 |
Disclosed is an optical filter for transmitting light in a narrow bandwidth centered about the wavelength lambda , including a birefringent half-wave crystal defining an optical path through the crystal and normal to the optical axis of the crystal, the thickness of the crystal effecting a 180 DEG phase change between the fast and slow components of light of wavelength lambda along the optical path; a first polarizer preceding the crystal in the optical path and having a first polarizing plane rotated 45 DEG about the optical path from the optic axis of the crystal; a first reflective surface preceding the first polarizer in the optical path and normal to the optical path; a second polarizer following the crystal in the optical path and having a second polarizing plane rotated 90 DEG about the optical path from the first polarizing plane; and a second reflective surface following the second polarizer in the optical path and normal to the optical path. The crystal may further be an electro-optic birefringent crystal, the filter then additionally including first and second electrodes affixed to the crystal and adapted to apply an electric potential across the crystal in the direction of the optical path, the transmission wavelength lambda thereby being tunable by adjusting the electric potential applied to the crystal.
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