JPS5619417A - Pyroelectric detector - Google Patents

Abstract

PURPOSE:To improve S/N by making it easy to handle a pyroelectric detector by making its constitution miniature and lightweight, by forming an electrooptical element, used as the method of varying periodically a dose of radiation rays such as infrared rays, in the same body with a pyroelectric element. CONSTITUTION:An electrooptical element, constituted by sandwiching liquid- crystal plate 18, whose light polarization surface turns when an electric field is applied, between polarizing plates 191 and 192 crossing at righ angles, is formed in the same body with pyroelectric element 11. In this constitution, applying a repetitive pulse voltage between pins 163 and 164 incident radiation rays are interupted by polarizing plates 191 and 192 while liquid-crystal plate 18 is not applied with any electric field and rotates the polarization surface while the electric field is applied to liquid-crystal plate 18, so that at least some of incident radiation rays will strike pyroelectric element 11 by penetrating polarizing plates 191 and 192. Namely, radiation rays incident to pyroelectric element 11 are periodically intermitted, and consequently a pyroelectric output can be obtained between pins 161 and 162, so that the incident radiation rays can be detected. Thus, the unit is made miniature and lightweight and its handling can be facilitated.