A laser absorption spectroscopy temperature measurement method and system based on the principle of interference modulation

Abstract

The invention provides a laser absorption spectrum temperature-measuring method and system based on an interference modulation principle. Employed components comprise a laser generation unit, a Mach-Zehnder optical fiber interferometer, a photoelectric detection unit and a data processing unit etc. A laser signal is generated and passes through the Mach-Zehnder interferometer, then the laser signal passes through a to-be-detected gas, and data is acquired and uploaded to the data processing unit through the photoelectric detector. Absorption light intensity data and mapping between the relative wave number and the absorption light intensity data are extracted from measurement data, a baseline and an initial value of an absorption spectrum parameter are obtained through fitting and corrected through iteration, an integral absorption rate is resolved according to the corrected absorption spectrum parameter, and a detected gas temperature is resolved through the integral absorption ratesof multiple spectral lines. According to the method and system, the structure of the optical system is simple, movable parts are avoided, the background radiation noise can be suppressed, the integraleffect is prominent, the application range is wide, the reliability is high, and the application prospect is wide.

Description

[0001] (1) Technical field [0002] The invention proposes a laser absorption spectrum temperature measurement method and system based on the principle of interference modulation, in particular to a Mach-Zehnder optical fiber interferometer that is multiplexed as an etalon and a light intensity modulator in a measurement system, and applies laser modulation technology to temperature measurement field. [0003] (2) Background technology [0004] The gas parameter measurement method based on laser absorption spectroscopy has been developed rapidly as a fast and highly sensitive non-contact measurement method. It is an effective method in the field of temperature and substance concentration measurement, and is widely used in combustion diagnosis and combustion control. etc., the application potential is huge and the prospect is promising. [0005] Typical single-path absorption spectrum measurement methods are divided into direct absorption method (DAS, Direct Absorption Spectros...

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Problems solved by technology

For example, James R.P.Bain and Michael Lengden published in "IEEE sensors journal" (IEEE sensors journal) Volume 16, Issue 3, Page 1-1 in 2015, entitled "Based on Tunable Diode Laser Technology Using Balanced Detection External Amplitude Modulation to Recover Absolute In the article "Recovery of Absolute Absorption Line Shapes in Tunable Diode Laser Spectroscopy using External Amplitude Modulation with Balanced Detection", it is pointed out that the modulation frequency of a typical optical chopper can generally reach kHz, and the modulation frequency of a lithium niobate amplitude modulator The frequency can reach MHz, but it needs to make the laser reach the polarization state and lose part of the light intensity, and the required optical path structure is more complicated than the traditional direct absorption method

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