JPS5655825A - Optical type temperature sensor - Google Patents

Abstract

PURPOSE:To reduce errors in measurement and enable direct connection to a digital device by a constitution wherein a plurality of birefringent ferrodielectric crystals different in length are arranged in parallel, the light is injected therein through the intermediary of a polarizer, the light passing the crystals is projected through the intermediary of a photoinspector and detected by a photoreceiving element. CONSTITUTION:The light from a opticalfiber for input is made into parallel beams by a lens 12 and these beams are injected into the single crystals 14-17 of LiNbO3 which are held by polarizing plates 13 and 13' at both ends thereof and are different in length. The beams projected therefrom are condensed by rod lenses 18-21, are led to opticalfiber 22-25, and outputs P1-P4 are obtained. The length t1-t4 of each crystal is set to be half of the preceding one sequentially. When the outputs P1-P4 of the light are turned into two-valued codes based on the half of the maximum output of the light, as shown by broken lines, the range T1-T2 of the temperature can be turned into binary digital codes, for instance, by four bits. By this constitution, errors in measurement can be reduced and, in addition, the device can be connected directly with a microcomputer and a digital meter without an AD transducer.