High-temperature optical fiber thermometer

Abstract

A high-temperature optical fiber thermometer made from single crystal sapphire has been developed for use from 600 to approximately 2000 °C. The device consists of a small blackbody cavity which is sputtered on the end of a thin (0.25–1.25-mm diameter, 0.05–0.30-m length) sapphire fiber, a connecting low-temperature glass fiber, and a conventional optical detector. The radiance from the cavity is used to measure its temperature. The present instrument is calibrated at a single temperature and uses the fundamental radiation laws to extrapolate to other temperatures. It is accurate and has a high sensitivity and rapid temporal response. There appear to be a number of applications of the device both in science and industry.

Review of temperature measurement

“…83 Typical fiber optic sensors include those based upon optical reflection, scattering, interference, absorption, fluorescence, and thermally generated radiation. One commercial system marketed consists of a cavity built onto the end of an optical fiber as illustrated in Fig.…”

ZrO2 thin-film-based sapphire fiber temperature sensor

“…Compared with silica fiber sensors, the sapphire fiber ones are generally much more difficult to fabricate because of the highly multi-moded nature of the cladding-less sapphire fiber. Dils proposed a sapphire fiber-based optical thermometer using blackbody radiation in early 1980s [2]. Later, spectrum-based sensing methods were studied in search of higher accuracy.…”

Review on an Advanced High‐Temperature Measurement Technology: The Optical Fiber Thermometry

“…The response of the thin film of aluminium oxide platinum to the temperature changes of the surrounding circumstance is expected to be rapid because of the very low thermal conductivity of sapphire [4]. The emissivity ε of the quasi blackbody cavity is not the ideal constant of 1, but is a function of wavelength and temperature.…”