| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to freely change the wavelength to be selected by generating parallel stripe patterns in a pair of substrates having spatial coarse and dense distributions of refractive indices by the electric fields generated according to voltage impression. SOLUTION: The interference fringes are generated if the voltage is impressed between adjacent ITO electrodes, for example, between the ITO electrodes 14a and 14b or between the ITO electrodes 14b and 14c. If light is made incident from the one surface of the a transparent substrate, the wavelength component of part of the light is selectively reflected. If, as an example, the voltage of 40V is impressed, the interference fringes of space frequencies 800pieces/mm (intervals are 1.25μm) are formed. If the incident angle of the light is set at 20 deg., the wavelength of the reflected light is 3.65μm. The light of 3.65μm of the incident light is, therefore, reflected at the reflection angle 20 deg.. If the voltage to be impressed between the electrodes is changed, the space frequencies (interference fringe intervals) may be changed and, therefore, the wavelength of the light to be reflected may be variously changed.
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