Spatial heterodyne monochromatic light interferogram error correction method based on spectral analysis

Abstract

The invention provides a spatial heterodyne monochromatic light interferogram error correction method based on spectral analysis. The method is characterized in that the spatial heterodyne spectrometer generates system errors due to asymmetry of two gratings, and interference fringes on a two-dimensional interference pattern are caused to rotate or distort. The method comprises the following steps: preprocessing an interference pattern, performing two-dimensional Fourier transform on the interference pattern to obtain frequency spectrum information of the interference pattern, extracting frequency spectrum information of a positive level of the interference pattern by adopting a rectangular filtering window, and moving the separated frequency spectrum of the positive level to a central position of a spectrogram; the information of the spectrum data of the area in the horizontal direction is reserved, the information of the spectrum data of the area in the vertical direction is eliminated, inverse Fourier transform is carried out on the processed spectrum data to obtain a corrected image, and correction of monochromatic light interferogram errors can be achieved based on the method. The method can be used for recovering distortion of monochromatic light two-dimensional interference fringes, quickly correcting monochromatic light interferogram errors and improving the correction accuracy, and can be widely applied to the field of monochromatic light interferogram error correction.

Description

(I) Technical field

[0001] The invention relates to a spatial heterodyne monochromatic light interference pattern error correction method based on spectrum analysis, which can correct inclined fringes in monochromatic light interference patterns and belongs to the field of spectrum information correction. (II) Background technology

[0002] The rapid development of spatial heterodyne spectroscopy technology benefits from the progress of precision devices and electronic technology. Due to its ultra-high spectral resolution, it has been widely used in detecting weak atmospheric signals. Spatial heterodyne spectrometers are used in many fields because of their small size, compactness, light weight, and the ability to widen the field of view through a prism. However, the measured spectrum will always fail to meet expectations due to some factors. This may be caused by inevitable optical defects in the integrated processing of the spectrometer, such as grating scratches and uneven beam splitting.

[0003] Spatial heterodyne spectroscopy is a new type of super-resolution spectroscopy technology. Due to the processing error of the optical system, the asymmetry of the dual optical paths causes the tilt and distortion of the two-dimensional interference fringes. The interference pattern obtained by the interferometer usually has interference pattern distortion caused by system errors, which causes the two-dimensional interference fringes to tilt and distort. Appropriate methods and algorithms are needed to correct the interference pattern. The two-dimensional Fourier transform method is based on the frequency domain of the interference pattern. It can quickly and accurately extract the information of the original wavefront from a single fringe interference pattern. By correcting the two-dimensional interference pattern signal, the accuracy of the interference pattern inversion spectrum can be improved.

[0004] Based on the above background technology, the present invention proposes a spatial heterodyne monochromatic light interference pattern error correction method based on spectrum analysis. Figure 2 The frequency domain spectrum is obtained by performing inverse Fourier transform, and the positive first-order spectrum is separated by a filter and translated to the center of the frequency domain, and its spectral information in the vertical direction is eliminated. The processed spectrum is inversely transformed to obtain the corrected image, thereby realizing the correction and restoration of the tilted fringe of the interference pattern. (III) Summary of the invention

[0005] The object of the present invention is to provide a method for correcting spatial heterodyne monochromatic light interference pattern errors based on spectrum analysis.

[0006] The object of the present invention is achieved in that:

[0007] Step S1, using a spatial heterodyne spectrometer to collect the interference pattern of monochromatic light, and preprocessing the collected interference pattern to achieve denoising and edge recognition of the interference image;

[0008] Step S2, performing a two-dimensional Fourier transform on the preprocessed interference pattern to obtain a frequency domain spectrum, extracting a positive first-order spectrum in the frequency domain through an appropriate rectangular filter window, and separating it from the spectrum, and then translating the separated positive first-order spectrum to the center position of the frequency domain spectrum;

[0009] Step S3, eliminating the spectrum information in the vertical direction of the positive first-order spectrum translated to the center position of the frequency domain spectrum, and only retaining its spectrum information in the horizontal direction, and then performing an inverse Fourier transform on the processed positive first-order spectrum information, so that the originally inclined fringes in the interference pattern can be restored to vertical, thereby obtaining a corrected interference pattern;

[0010] To ensure the stability of the collected interference pattern, the distance between the light source and the spatial heterodyne spectrometer is kept fixed and on the same horizontal optical platform to avoid the light source position moving and causing the light source uniformity to change. The light source can use a collimator. By selecting a suitable excitation light source and optimizing the optical path, a clearer interference pattern can be captured;

[0011] During the acquisition process, the monochromatic light interference pattern image is easily affected by factors such as background noise, grating pollution, thermal noise, etc., which leads to the introduction of various random noises in the interference pattern, causing interference to the interference information. In order to ensure the acquisition of accurate spectrum data information, effective methods must be adopted to eliminate these noises;

[0012] When extracting the interference pattern and obtaining the positive first-order spectrum in the spectrum diagram after two-dimensional Fourier transformation, a filter window of appropriate size should be selected to avoid introducing other errors. (IV) Description of the drawings

[0013] Figure 1 The present invention discloses a method for correcting spatial heterodyne monochromatic light interference pattern errors based on spectrum analysis.

[0014] Figure 2 The experimental device and optical path schematic diagram of the present invention are composed of 1 monochromatic light source, 2 spatial heterodyne spectrometer, and 3 host computer. (V) Specific implementation methods

[0015] The present invention will be further described below in conjunction with specific embodiments.

[0016] Figure 2 The schematic diagram of information collection during the experiment. The monochromatic light source 1 adopts a rectangular light source, and the light source is placed on the left side of the spatial heterodyne spectrometer 2. By controlling the incident energy of the monochromatic light source, the radiation intensity of the light source is controllable and stable. The spatial heterodyne spectrometer 2 and the host computer 3 transmit data through the network port.

[0017] The spatial heterodyne monochromatic light interference pattern error correction method based on spectrum analysis described in the present invention is to control the input energy of the monochromatic light source 1 while keeping the distance between it and the spatial heterodyne spectrometer 2 fixed, so as to ensure that the interference pattern collected by the spectrometer has uniform illumination and clear imaging. The spatial heterodyne spectrometer 2 collects interference image information and transmits it to the host computer 3. The above-mentioned interference pattern is subjected to image preprocessing to eliminate redundant noise information.

[0018] The method for quickly correcting the interference pattern error adopted by the present invention is to perform a two-dimensional Fourier transform on the interference pattern, use an appropriate rectangular filter window to extract the positive first-order spectrum in the frequency domain, eliminate the spectrum information in the vertical direction of the separated positive first-order spectrum, and only retain its spectrum information in the horizontal direction, and then perform an inverse Fourier transform on the processed positive first-order spectrum information, so that the originally inclined stripes in the interference pattern can be restored to vertical, thereby obtaining the interference pattern after error correction.

[0019] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to specific embodiments, a person skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention. The technologies, shapes, and structural parts not described in detail in the present invention are all well-known technologies.

Claims

1. A spatial heterodyne monochromatic light interference pattern error correction method based on spectrum analysis, characterized in that: The steps include: Step S1, obtaining a monochromatic light interference pattern and preprocessing it; Step S2, performing a two-dimensional Fourier transform, extracting a positive first-order spectrum through a rectangular filter window, and moving the extracted positive first-order spectrum to the center of the spectrum graph; Step S3, only retaining the information of the spectrum in the horizontal direction, eliminating the information in the vertical direction, and performing inverse Fourier transform on the processed spectrum data to obtain a corrected image.

2. The method according to claim 1, characterized in that In step S1, a monochromatic light interference pattern is collected. In the experiment, the light source is placed on a specific optical platform to ensure the stability and controllability of the radiation intensity of the light source, and the background environment should be relatively stable to avoid interference from other light sources.

3. The method according to claim 1, characterized in that In step S1, the system error caused by the asymmetry of the two gratings of the spectrometer is obtained, and then the CCD detector obtains the interference pattern with fringe tilt. When extracting the spectrum data corresponding to the interference pattern, it should be preprocessed to reduce the interference caused by noise and the response inhomogeneity of the detector.

4. The method according to claim 1, characterized in that In step S2, the interference pattern is subjected to a two-dimensional Fourier transform, and a suitable rectangular filter window is used to extract the positive first-order spectrum in the spectrum diagram, and the extracted positive first-order spectrum is moved to the center of the spectrum diagram to facilitate correction processing thereof.

5. The method of claim 1 is characterized in that, in step S3, by retaining the spectrum information in the horizontal direction of the spectrum and eliminating the spectrum information in the vertical direction, the core information of the interference pattern spectrum is retained, and a two-dimensional inverse Fourier transform is performed on the processed data to obtain a corrected image.

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