A method for improving the signal-to-noise ratio of the low-signal-to-noise ratio frequency band of the Fourier transform infrared spectrometer

An infrared spectrometer and a low signal-to-noise ratio technology, which is applied in the field of improving the signal-to-noise ratio of the low signal-to-noise ratio frequency band of a Fourier infrared spectrometer, can solve the problems of low identification and detection accuracy, low signal-to-noise ratio in some frequency bands, and spectral energy. Unbalanced distribution and other problems, to achieve the effect of improving the signal-to-noise ratio, improving the balance of the background spectral energy distribution, and reducing the unbalanced degree

Inactive Publication Date: 2016-08-24
TSINGHUA UNIV
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Problems solved by technology

[0007] In order to overcome the above-mentioned shortcoming of the prior art, the object of the present invention is to provide a kind of method that improves Fourier transform infrared spectrometer partial low signal-to-noise ratio frequency band signal-to-noise ratio, to the energy distribution on the FTIR background spectrum by frequency-selective Absorption and subtraction to achieve a balanced background spectral energy can effectively avoid the defects of low recognition and detection accuracy at the weaker part of the spectral background energy distribution, thereby solving the problem of unbalanced background spectral energy distribution and partial frequency band signal in the Fourier transform infrared spectrometer. The problem that the noise ratio is too low is not conducive to detection

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  • A method for improving the signal-to-noise ratio of the low-signal-to-noise ratio frequency band of the Fourier transform infrared spectrometer
  • A method for improving the signal-to-noise ratio of the low-signal-to-noise ratio frequency band of the Fourier transform infrared spectrometer
  • A method for improving the signal-to-noise ratio of the low-signal-to-noise ratio frequency band of the Fourier transform infrared spectrometer

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Embodiment approach 1

[0039] 1. Determination of the transmittance function of the light intensity subtraction method

[0040] Different companies and different types of FTIR have different background spectral distributions due to their light sources, detectors, and beam splitter performances. The present invention uses Figure 4 FTIR background spectrum in , as an example to explain the method of equalizing its background spectrum, this method is similar to Figure 4 The most common FTIR background spectrum in the mid-to-mid-infrared range, with high energy distribution in the middle and low energy distribution in the ends, is universal.

[0041] Such as Figure 6 As shown, the basic structure still adopts the FTIR detection optical path, the difference is that the first absorption sheet 13 and the second absorption sheet 14 are arranged on the emission route of the infrared light source 2, wherein the first absorption sheet 13 absorbs the middle and low frequencies through high frequency , Abso...

Embodiment approach 2

[0073] Use the fork slider to switch whether to place an absorber in the optical path, so as to make full use of the original background spectrum and the background spectrum after absorption modulation to achieve a higher signal-to-noise ratio.

[0074] The simulation results of the above-mentioned embodiment 1 are as follows Figure 15 As shown, although the energy distribution of the low frequency band and the high frequency band has been greatly improved, this improvement is at the expense of the energy decrease of the middle frequency band where the original energy distribution is relatively high. In order to avoid this energy drop, you can use the fork slider to switch whether to insert an absorber in the optical path behind the light source. When switching to the working condition without an absorber, detect the original spectrum to maintain high signal-to-noise in the middle frequency band Ratio; then switch to the state with the absorbing sheet, use the absorbing sheet...

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Abstract

The invention relates to a method for improving the signal-to-noise ratio at ultralow signal-to-noise ratio frequency band of a Fourier infrared spectrometer. An absorbing sheet which can be penetrated by high frequency and can attenuate middle and low frequencies and an absorbing sheet which can be penetrated by low frequency and can attenuate middle and high frequencies are placed in a light path behind an infrared source, so as to absorb a part of light energy emitted by the light source in a targeted manner at certain frequencies and achieve the effect of balancing the background spectral energy distribution; then the light energy of the light source is increased to enable the total energy received by an infrared detector to be equal to the received total energy before the absorbing sheets are added, thus, the energy of the background spectrum at the original low energy distribution position can be greatly improved and the signal-to-noise ratios at the frequency bands are remarkably improved; and the method can avoid the problems of low signal-to-noise ratio at certain frequency bands and low detection sensitivity, caused by poor Fourier infrared spectral energy distribution balance.

Description

technical field [0001] The invention belongs to the field of spectral measurement of a Fourier transform infrared spectrometer, and in particular relates to a method for improving the signal-to-noise ratio of a relatively low signal-to-noise ratio frequency band of a Fourier transform infrared spectrometer. Background technique [0002] In order to solve the severe environmental pollution problem, it is essential to seek a powerful monitoring method. In recent years, Fourier transform infrared spectroscopy (FTIR) has been widely used in the detection of pollutants in the atmosphere and water sources due to its fast measurement speed, wide detection wavenumber range, and simultaneous measurement of multiple components. Emergency detection of environmental safety in sexual disaster events. Usually, the schematic diagram of the optical path for FTIR detection of gas is as follows: figure 2 As shown in the figure, a He-Ne laser 1 and an infrared light source 2 are used to emit...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N21/3504G01N21/15G01J3/433
Inventor 王昕李岩尉昊赟
Owner TSINGHUA UNIV
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