A Comparison between Two Heterodyne Light Sources Using Different Electro-Optic Modulators for Optical Temperature Measurements at Visible Wavelengths
Optical sensors have been investigated and widely deployed in industrial and scientific measurement and control processes, mainly due to their accuracy, high sensitivity and immunity to electromagnetic interference and other unique characteristics. They are especially suited for harsh environments applications, where no commercial electrical sensors are available for long-term stable operations. This paper reports a novel contact optical high temperature sensor targeting at harsh environments. Utilizing birefringent single crystal sapphire as the sensing element and white light interferometric signal processing techniques, an optical birefringence based temperature sensor was developed. With a simple mechanically structured sensing probe, and an optical spectrum-coded interferometric signal processor, it has been tested to measure temperature up to 1600 °C with high accuracy, high resolution, and long-term measurement stability.