JPS5657926A - Optical temperature detector - Google Patents

Abstract

PURPOSE: To obtain an optical temperature detector of explosion-proof structure having a high resistance to the noise and a stable working, by vibrating the diaphragm whose resonance frequency varies by the temperature with the electric pulse obtained by giving a photoelectric conversion to the optical energy and sensing optically the resonance frequency.

CONSTITUTION: The optical pulse sent from the light source 2 which received the output of the pulse oscillator 1 passes through the optical waveguide path 3 to be branched into two routes 45 and 49 via the optical distributor 4. One light passing through the route 45 is turned into the pulse voltage through the photoelectric transducer 5 to give a displacement to the piezoelectric element 6. Thus the diaphragm 8 is vibrated by the optical energy of the optical pulse. On the other hand, the other light passing through the route 49 passes through the optical waveguide path 49' within the diaphragm 8 and receives a forced modulation via the lens 9 to be sent to the optical detector 11. And the light in the detector 11 is then converted into the electric signal to be sent to the frequency counter 12. Thus the resonance frequency of the diaphragm 8 is detected. Furthermore, a time-averaging is given to the measured value through the averaging circuit 13 to obtain a higher accuracy. Based on the value of the resonance frequency thus obtained, the corresponding temperature is obtained.

COPYRIGHT: (C)1981,JPO&Japio