Light path online calibration type cavity enhanced atmosphere trace gas detection system

Abstract

The invention relates to a light path online calibration type cavity enhanced atmosphere trace gas detection system. The system comprises a light source, a light source driving device, non-spherical lenses, a filter, diaphragms, an optical cavity, a one-divided-two type optical fiber bundle, a light attenuation signal detection device, a light spectrum detector, and the like. Lights emitted from the light source firstly pass through a non-spherical lens to be collimated, are coupled, then enter the optical cavity formed by two mirrors with high reflectivity, and are emitted back and forth a plurality of times inside the cavity so as to provide a absorption light path increasing effect. The lights transmitted from the other side of the optical cavity are focused on an incidence end surface of a one-divided-two type optical fiber bundle through a non-spherical lens. One emergence end of the one-divided-two type optical fiber bundle is connected with the light attenuation signal detection device, and the other emergence end of the one-divided-two type optical fiber bundle is connected with the light spectrum detector. The light source has two driving modes of narrow pulse and constant current, wherein the narrow pulse driving mode is used for light attenuation signal measuring so as to determine the absorption light path during gas measuring, the constant current driving mode is used for absorption light spectrum measuring to obtain the column concentration of the trace gas in the measured atmosphere, and the concentration value of the measured gas can be obtained according to both measurement results.

Description

technical field [0001] The invention relates to a detection device for detecting gas concentration by using an optical cavity, more specifically a cavity-enhanced point measuring instrument for high-sensitivity detection of atmospheric trace gas with an optical path online calibration function. Background technique [0002] Differential absorption spectroscopy (DOAS) based on optical methods has become a common method for atmospheric trace gas monitoring. It has the characteristics of fast response, non-contact measurement and simultaneous online monitoring of multiple components. The concentration of trace gases in the atmosphere is usually on the order of ppbv or even pptv. For DOAS technology, the detection sensitivity can be improved by increasing the absorption path. At present, the commonly used long optical path DOAS instrument has a measurement optical path of several kilometers or even tens of kilometers, and the detection sensitivity can reach the pptv level. How...

AI Technical Summary

Problems solved by technology

However, the existing optical path calibration method is offline, that is, it is impossible to calibrate the optical path at the same time as the actual atmospheric measurement, and the optical path can only be calibrated periodically

Due to the degradation of the reflectivity of the lens during the continuous measurement process, the optical path will change, and when the degradation occurs is unpredictable, so the off-line regular calibration cannot obtain accurate optical path information in time, resulting in a certain period of time. Deviations in the measurement results, so that the purpose of continuous and accurate measurement of atmospheric trace gases cannot be guaranteed for a long time

Images