12 results about "Wavelength modulation spectroscopy" patented technology

The invention relates to the technical field of impurity gas detection control, and discloses an impurity detection control method and system for high-purity oxygen, and the method comprises the steps: arranging a plurality of groups of TDLAS detection probes and temperature vibration monitoring units, and obtaining a spectrum harmonic signal and temperature and vibration data; the concentration is inverted through wavelength modulation spectrum demodulation and temperature and pressure disturbance compensation; pCA fusion denoising processing is executed through the edge calculation unit, and correction concentration is output; and abnormity is judged through a multi-scale dynamic threshold mechanism and linkage control is carried out. Compared with a common single-point probe or traditional low-pass filtering in the prior art, the technical problem that interference between impurity concentration change and environmental disturbance cannot be effectively handled especially in a high-vibration and high-temperature-difference environment is solved. According to the invention, through multi-channel cooperative weighting, PCA fusion compensation and a dynamic threshold determination mechanism, accurate detection control of the high-purity oxygen conveying pipeline in an industrial environment is realized, and the automation level of pipeline impurity gas detection control is improved.

The invention discloses a saturated spectrum processing method for wide-range detection of an absorption spectrum of a tunable diode, and relates to the technical field of spectrum gas detection. According to the saturated spectrum processing method for wide-range detection of the absorption spectrum of the tunable diode, an effective spectrum signal is obtained by performing denoising and baseline correction on an original absorption spectrum signal, a plurality of spectrum characteristic parameters are extracted to calculate a saturated quantized value, and a complete absorption spectrum line contour is reconstructed by adopting a spectrum reconstruction algorithm according to the quantized value, so that the wide-range detection of the absorption spectrum of the tunable diode is realized. The method comprises the following steps of: constructing a saturation quantitative evaluation system, a layered self-adaptive spectrum reconstruction strategy, a dual-mode detection fusion mechanism and a working condition compensation model, calculating weights of an absorption spectrum and a wavelength modulation spectrum through an S-type function, correcting a preliminary concentration value by combining environment temperature, pressure and a compensation model, and outputting an accurate final gas concentration. Without additional hardware, wide-range high-precision gas detection is realized, and environmental interference and saturation influence are eliminated.

The application discloses a kind of multi-dimensional flow field imaging system and method based on wavelength modulation spectrum, the system includes: one-dimensional imaging system, for by multiple sets of laser beam expander and collimating lens, the point laser spot of input laser is deformed to obtain multiple sets of strip laser spot, input multiple sets of strip laser spot into the flow field to be measured and obtain two-dimensional image reconstruction information by multiple sets of one-dimensional linear array high-speed infrared camera;Two-dimensional imaging system is used to input laser through the laser beam expander and collimating lens of prearranged arrangement, obtain three-dimensional image reconstruction information by two-dimensional high-speed infrared camera;Computing system is used to calculate multiple sets of two-dimensional image reconstruction information and three-dimensional image reconstruction information, and the state information of the flow field to be measured with spatial resolution is output by speed;State information includes component temperature, component pressure and component concentration.The application realizes the WMS technology from zero-dimensional spatial resolution to one-dimensional, two-dimensional, three-dimensional spatial resolution, realizes the accurate measurement to flow field.

This application provides a gas detection system and method based on near-infrared wavelength modulation and mid-infrared pulsed laser synergy, relating to the fields of spectroscopic gas detection and industrial flue gas monitoring. In industrial sites such as biomass power plants, hazardous waste incineration plants, and aluminum smelters, the flue gas generated in their flues has complex compositions. Traditional chemical detection methods are insufficient to meet real-time requirements, while other optical detection methods, such as Fourier transform infrared spectroscopy and ultraviolet differential spectroscopy, suffer from high costs and difficulty in avoiding water vapor interference. To address this, a system and method for detecting the concentration of gaseous pollutants in industrial flue gas based on near-infrared wavelength modulation and mid-infrared pulsed laser synergy is proposed. This system combines near-infrared wavelength modulation spectroscopy with mid-infrared pulsed direct absorption spectroscopy, employing multiple near-infrared tunable continuous lasers and mid-infrared tunable pulsed lasers. It utilizes time-division multiplexing and polling modes, combined with a common optical path design, to achieve real-time online monitoring of the concentration of various gaseous pollutants, ultimately significantly reducing the overall system cost.

This invention discloses a high-precision gas parameter measurement system and method based on the harmonic reconstruction principle, belonging to the field of data processing technology. The method includes the following steps: S1, processing the modulated transmittance signal to obtain harmonic curves from order 0 to k0; S2, obtaining the variation curves of each order harmonic with respect to the laser frequency based on the laser frequency variation signal and the harmonic curves from order 0 to k0; S3, determining the molecular absorption spectrum based on the variation curves of each order harmonic with respect to the laser frequency; S4, analyzing the molecular absorption spectrum to determine the physical parameters of the gas being measured. This invention retains the core advantages of wavelength modulation spectroscopy, such as high signal-to-noise ratio, strong anti-interference capability, and high measurement accuracy, while providing a new measurement method for high-precision calibration of spectral physical parameters, high-precision measurement of gas parameters under weak absorption conditions, and gas monitoring in complex industrial environments, effectively expanding the measurement efficiency and application scope of this technology.

Embodiments of the disclosure are drawn to apparatuses and methods for anomalous gas concentration detection. A spectroscopic system, such as a wavelength modulated spectroscopy (WMS) system may measure gas concentrations in a target area. However, noise, such as speckle noise, may interfere with measuring relatively low concentrations of gas, and may lead to false positives. A noise model, which includes a contribution from a speckle noise model, may be used to process data from the spectroscopic system. An adaptive threshold may be applied based on an expected amount of noise. A speckle filter may remove measurements which are outliers based on a measurement of their noise. Plume detection may be used to determine a presence of gas plumes. Each of these processing steps may be associated with a confidence, which may be used to determine an overall confidence in the processed measurements / gas plumes.

This invention discloses a method for coordinated wavelength correction of oxygen absorption in a TDLAS gas analyzer, comprising the following steps: S1, firstly, extracting the second harmonic signal of oxygen using wavelength modulation spectroscopy technology with the TDLAS gas analyzer; S2, analyzing the second harmonic signal of oxygen absorption to extract the absorption peak amplitude and position information; S3, determining whether the center wavelength has shifted, i.e., whether the absorption peak amplitude has deviated from the preset range. If yes, proceed to step S4; otherwise, return to step S1; S4, if the absorption peak amplitude has deviated, using a coordinated control algorithm of temperature control coarse adjustment and current fine adjustment for correction. This invention eliminates the need for a reference gas chamber and spectroscopic structure, maintaining simplicity and reliability in hardware; it also avoids the problems of traditional harmonic peak search being susceptible to noise interference and response lag, enabling fast, stable, and high-precision automatic wavelength correction under complex operating conditions, effectively improving the long-term measurement stability and detection accuracy of the TDLAS gas analyzer.

The application discloses a propellant stability detection method based on photoacoustic spectrum. The method is characterized in that: a heating tank loaded with propellant is placed in a water bath kettle for uniform heating and generating decomposition gas containing carbon dioxide; the propellant decomposition gas is transported to a resonance photoacoustic cell; a wavelength modulation spectrum technology is used to modulate the output laser of a tunable laser; the laser excites the propellant decomposition gas in the resonance photoacoustic cell; the gas absorbs the excitation light to generate a sound signal based on the photoacoustic effect; the sound signal is received by an acoustic sensor and demodulated by a lock-in amplifier; the lock-in amplifier demodulates a second harmonic sound signal based on the frequency of the cosine modulation signal in the wavelength modulation; the amplitude of the second harmonic sound signal is analyzed to obtain the concentration information of carbon dioxide in the decomposition gas; and the concentration content of carbon dioxide in the propellant decomposition gas can reflect the stability of the propellant. The method can provide a quantitative, simple, safe and convenient detection method for the stability detection of the propellant.

The application provides a method for quickly measuring laser light frequency response, which extracts effective absorption information harmonic signal to obtain accurate laser light frequency response through specific environment absorption spectrum measurement, uses a method of multiplying a reference signal to transfer absorption information to a direct current part, extracts a normalized harmonic signal insensitive to a phase through low-pass filtering combined with a double-channel demodulation mode, and uses a nonlinear least square fitting to take a frequency modulation parameter of the laser as a fitting parameter to realize accurate measurement of the light frequency response. The application solves the problem of fast measurement of wavelength modulation technology laser frequency-time response, applies the laser light frequency-time response measurement method to related engineering fields, solves key technical problems for accurate measurement of complex environment component concentration, provides accurate quantitative parameters for accurate construction of an absorption model, and further expands the application range of wavelength modulation spectroscopy technology.

The invention discloses a water vapor column concentration laser telemetering system and method based on TDLAS-WMS. The system comprises an electronics control unit, a laser modulator, a near-infrared laser, a collimator, a dichroscope, a first reflector, a second reflector, an optical convergence telescope, a narrow-band filter, a detector, a ranging radar and a visible light laser. According to the invention, the TDLAS-WMS-2f / 1f technology is used, and high-precision and high-stability water vapor column concentration measurement is realized. The tunable semiconductor laser absorption spectrum is combined with the wavelength modulation spectrum technology, signal processing is carried out according to the ratio of second harmonics to first harmonics, and interference caused by light intensity fluctuation, atmospheric turbulence and non-absorption loss in the light path transmission process can be effectively eliminated.

This application discloses a dual-range H2O2 gas concentration monitoring system and method, belonging to the field of environmental gas detection. In this dual-range H2O2 gas concentration monitoring system, a main circuit module drives a transmitting unit to emit a laser of a characteristic wavelength, wherein the driving signal includes a low-frequency modulation signal and a high-frequency modulation signal; a receiving unit receives the laser signal after it passes through the H2O2 gas to be measured and converts it into an electrical signal; the electrical signal is divided into a first path and a second path for parallel processing; in the first path, the electrical signal is processed based on wavelength modulation spectroscopy to obtain a first concentration value; in the second path, the electrical signal is processed based on direct absorption spectroscopy to obtain a second concentration value; according to a preset high / low range switching mechanism, the final gas concentration is output by combining the first and second concentration values. This system and method can achieve automatic switching between high and low ranges, ensuring high-precision measurement across the entire range.