Optical temperature sensor with linear electro-optical modulation

摘要

The sensor includes a laser which delivers a light beam through an optical fibre (2). a polariser (3) and a quarter-wave plate (4). The beam then enters an electro-optical and thermo-optical crystal (5) having its axes parallel with those of the plate. The birefringence of the crystal has a linear variation with the electric field applied to the crystal surfaces. The birefringence has also a linear variation with the crystal temperature. The light emerging from the crystal is sent to a second quarter-wave plate (6) and an analyser (7). An optical fibre (8) guides the beam towards a photodiode giving an electrical signal proportional with the light intensity.