| 摘要 |
PURPOSE:To keep always the quantity of transmitted light constant, by detecting the variance of the temperature of a substrate due to an electrostrictive material and controlling the voltage applied to the electrode on the substrate on the basis of the detection signal by a voltage controller. CONSTITUTION:In the PLZT optical shutter where a substrate 3 consisting of an electrostrictive material where an electrode 4 for voltage application is formed is arranged between a pair of polarizers 1 and 2, the variance of the temperature of the substrate 3 is detected by a thermosensitive element 7. When the temperature of the substrate 3 rises more than the initial temperature of 25 deg.C, a temperature correcting circuit 8 controls a high-voltage power supply circuit 5 on the basis of a detection signal SD from the thermosensitive element 7 so that the output voltage from the high-voltage power supply circuit 5 rises. As the result, the voltage applied to the electrode 4 is raised, and the double refractive index of the substrate 3 is kept constant. When the temperature of the substrate 3 falls, the applied voltage is dropped to keep the double refractive index constant, and thus, a quantityIof transmitted light from the polarizer 2 is kept constant independently of the variance of the temperature of the substrate 3. |
