| 摘要 |
PURPOSE:To control the transmittance of rays optically by using a material of which the refractive index changes when irradiated with light for the material of an intermediate layer of an optical interference filter and changing the refractive index optically. CONSTITUTION:This light valve is designed to control the transmittance of light by means of light based on the effect in the change of the refractive index which is increased by an interference phenomenon. For example, a galss film 1 having n1=2.64 refractive index, a glass film (reflection layer) having n2=1.38 refractive index, and an intermediate layer 3 of a dielectric material having n3 refractive index are disposed on an ordinary optical glass substrate 4 as shown in the figure. The optical interference filter constituted in the above-mentioned way allows the transmission of only the light of the specific wavelength band determined by the refractive index and thickness of the layer 3; therefore, it is possible to change the central wavelength of transmission and to control the intensity of light by irradiating light perpendicularly to the optical interference filter and changing the refractive index of the layer 3. |
