| 摘要 |
In an optical filter, a pair of polarization filters allows transmission of light therethrough when i) the light has a wavelength band equal to or more than a first wavelength regardless of a light oscillation direction, the wavelength band including a wavelength of infrared light and ii) the light has a wavelength band less than the first wavelength and is linearly polarized. An optical rotation control element, disposed between the paired polarization filters, allows the light to be transmitted therethrough during which optical rotation of the light is changed selectively depending on application or non-application of voltage to the optical rotation control element. The polarization filters have polarization planes, respectively, which are in parallel with each other or the polarization plane of one of the polarization filters is rotated from that of the other by an angular amount of rotation resulting from the polarization of the optical rotation control element. |
