| 摘要 |
PURPOSE:To decrease the measuring errors of an optical temp. sensor by the constitution consisting in using a double refractive crystal having a large thickness and providing a half mirror for reflecting again part of the light past the crystal into the crystal on the exit face of the crystal. CONSTITUTION:The light from a light emitting element 2 is transmitted through the half mirror 12 and is made incident on a sensor head 4A consisting of a polarizer 5, the double refractive crystal 6 provided with the half mirror 13 on the exit face and a polarizer 7. The light which is transmitted therethrough and has the intensity as the function of temp. is received by a photodetector 9 and the direction of the temp. change is discriminated by a level discrimination circuit 14. The result thereof is put into a counter 15. On the other hand, the light reflected by the mirror 13 is again returned to the mirror and is received by a photodetector 16, of which the output is inputted to the counter 15. Addition and subtraction are made by the counter 15 and the temp. is displayed on a display part 19. The errors arising from the intensity change of the light and the fluctuation of the transmission loss are thus eliminated and the measurement with high accuracy is made possible. |
