High sensitivity optical system of DOAS analyzer

Abstract

The present invention relates to a high sensitivity optical system of a differential optical absorption spectroscopy (DOAS) analyzer for gas concentration detection. According to the system, two optical axes of a collimating lens set and a condenser lens set intersect on a side of a large lens to form the optical axis intersection point, wherein the collimating lens set is arranged perpendicular to the condenser lens set; optical axes on both sides of the collimating lens set are respectively provided with a light source and a transmitted light reflector; optical axes of both sides of the condenser lens set are respectively provided with an optical fiber spectrometer and a reference light reflector; a spectroscope plated with a reflecting film is positioned on an angular bisector of a right angle, wherein the optical axes of the two adjacent sides of the collimating lens set and the condenser lens set intersect to form the right angle; the spectroscope is concurrently and obliquely arranged on the optical path comprising the half outgoing beam of the collimating lens set and the half incoming beam of the condenser lens set in the angle of 45 DEG, and the other half outgoing beam of the collimating lens set and the other half incoming beam of the condenser lens are provided with moveable baffles, wherein the positions of the movable baffles are switchable; the half of the beam emitted by the light source enters the reference light path, and the other half of the beam enters the measurement light path. According to the present invention, under the same light source radiationconditions, the light energy passing through the optical system of the present invention is strong, the signal-to-noise ratio is high, and the measurement precision is improved.

Description

technical field [0001] The invention relates to a high-sensitivity optical system of a DOAS analyzer for on-line measurement of gas concentration using optical and spectroscopic techniques. The optical system is a physical channel for gas concentration information transmission and is the core component of the entire system. Background technique [0002] Industrial flue gas, especially boiler flue gas from thermal power plants contains a large amount of SO 2 , NO X , NH 3 Many harmful components, such as desulfurization and denitrification, must be purified before they can be discharged up to the standard. Continuous Emission Monitoring System (CEMS, Continuous Emission Monitoring System) is an important monitoring equipment to guide the closed-loop operation of desulfurization and denitrification systems in power plants, and it is also an important monitoring equipment for flue gas emissions. With the continuous advancement of my country's energy conservation and emission...

AI Technical Summary

Problems solved by technology

At present, in DOAS analyzers that use a single detector to obtain reference light intensity and transmitted light intensity in time-sharing, the optical system mostly adopts a semi-transparent and semi-reflective design, or on this basis, a UV anti-reflection coating is coated on the surface of the lens, whether it is Whether the reference light or the transmitted light needs to pass through the same semi-transparent mirror twice, the light emitted by the light source can only theoretically enter a quarter of the energy into the photodetector, resulting in low energy utilization; in addition, most of the optical design Without consideration of chromatic aberration correction, for energy-based rather than imaging-based systems, a considerable part of the energy will be lost again when the broadband light beam passes through the optical system, especially when the radiant light intensity of the light source is weak or the concentration of the measured component is high or In extremely low conditions, the signal-to-noise ratio of the signal entering the photodetector is significantly reduced, resulting in low sensitivity and measurement accuracy of the DOAS analyzer, and the light source must be replaced, resulting in a short service life of the light source

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