Application of Calibration-Free Wavelength Modulated Spectral Absorption Technique in Temperature Measurement under Ultra-Short Optical Path

Abstract The measurement of gas temperature parameters is of great significance in scientific research and industrial production. Wavelength modulation technology, as a non-contact optical detection means, has the characteristics of strong anti-interference ability and is widely used in various complex and harsh environments. The accuracy of temperature measurement is affected by short optical paths and weak absorption. In this paper, a calibration-free wavelength modulated ultra-short optical path measurement system is established, and the selection rules of spectral lines under the ultra-short optical path and weak absorption are proposed. The measurement results of wavelength modulation without calibration are in good agreement with those of thermocouple temperature measurement, and the relative error is less than 10%.