| 摘要 |
PURPOSE:To pass all of light through crystal for compensation and to improve an SN ratio and contrast by providing a nonreflective coating to the surface of an electrooptic crystal part on the side of a readout light source and the passing surface of the crystal for compensation. CONSTITUTION:A transparent conductive multilayered film 120f is formed on the photoelectric surface of the electrooptic crystal 120 put in the glass container 3 of a space optical modulator and a transparent conductive film 120g is formed on the other surface. An SiO2 layer 120h is formed by sputtering and vapor deposition to thickness lambda/4n except at the electrode wiring part of the peripheral part of the conductive film 120g. Further, both surfaces of the electrooptic crystal 122 for compensation are coated with SiO2 layers 122f and 122g to thickness lambda/4n. Those SiO2 layers 120h, 122f, and 122g are used as nonreflective coating layers. Further, both surfaces of a lambda/2 plate 121 made of quartz are coated with MgF2 films 121f and 121g to thickness lambda/4n. Then, all of light is passed through the crystal 122 to remove noises which are not an object of compensation, thereby improving the SN ratio and contrast.
|
