| 摘要 |
A tunable filter is provided with a polarizing branch element that makes two linearly polarized light components with mutually orthogonal vibrating d irections branch off from input light, a wavelength dispersion type spectros copic element that separates two linearly polarized light components made by the polarizing branch element into two spectrum images that correspond to t he two linearly polarized light components and are spatially divergent with respect to one direction, and a reflective type spatial modulation element t hat modulates and reflects the linearly polarized light component in each wa velength region independently of the two spectrum images with each other, wh erein the modulated light component reflected from the reflective type spati al modulation element is reentered in the wavelength dispersion type spectro scopic element and the polarizing branch element, so that one output light c omponent with a wavelength region modulated by the reflective type spatial m odulation element and another output light component with a non-modulated wa velength region are separately output, and the input light and reentered lig ht components to the polarizing branch element and the input light and reent ered light components to the wavelength dispersion type spectroscopic elemen t are parallel light fluxes.
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