High-precision quantitative measurement method of interference spectrum imager

Abstract

The invention discloses a high-precision quantitative measurement method of an interference spectrum imager, which comprises the following steps of: scanning the optical path difference of a time modulation type interferometer by taking a scattering time domain interference signal as a calibration light source, and collecting a laminated interference image sequence; extracting a time domain discrete interference signal of each pixel from the laminated interference image sequence, and performing Fourier transform on the time domain discrete interference signal to obtain a corresponding spectral signal; the method comprises the following steps: extracting signals of same spectral channels of all pixels to form a single-band image, performing Fourier transform on interference signals along a field-of-view correlation optical path difference modulation dimension, separating modulation items through a frequency domain filtering method, and obtaining a relative spectral response coefficient according to a non-uniformity distribution condition of non-modulation items; and correcting the modulation item by using the relative spectral response coefficient so as to obtain an interference fringe modulation efficiency coefficient. The high-precision quantitative measurement method of the interference spectral imager is realized, the spectral resolution and the calibration spectral range are convenient to adjust, and the method has the advantages of high precision, high luminous flux and high spectral resolution.

Description

Technical Field

[0001] The invention relates to a high-precision quantitative measurement method for an interference spectrum imager, which can be used to realize a spectrum calibration technology for an interference spectrum imager with high throughput and high spectral resolution. Technical Background

[0002] The interference data collected by the interferometric spectral imager will be distorted due to the inconsistent spectral response of the instrument's detection pixels, and the deviation of the interference data will cause obvious changes in the restored spectrum, so the relative spectral response of the instrument needs to be calibrated with high precision. At present, the most commonly used technical means is to introduce the uniform light source produced by a monochromator or other quasi-monochromatic light source into the interferometric spectral imager, and then obtain the relative spectral response calibration result of the instrument. However, the luminous flux and spectral resolution of the above-mentioned monochromatic light source are low, and the spectral resolution and spectral range cannot be dynamically adjusted according to the instrument to be calibrated. Time-modulated interferometric spectroscopy technology can easily change the parameters of the output spectrum by adjusting the interference sampling parameters, providing a technical basis for constructing a controllable frequency domain quasi-monochromatic calibration light source. Summary of the invention

[0003] The purpose of the present invention is to provide a high-precision quantitative measurement method for an interference spectrometer, to provide a calibration scheme with high light flux, high spectral resolution and adjustable spectral resolution, and to solve the technical problem of interference signal aliasing during the calibration process of the interference imaging spectrometer.

[0004] The technical solution adopted by the present invention is a high-precision quantitative measurement method of an interference spectrum imaging instrument, which is special in that it is applicable to an interference spectrum imaging system, and includes the following steps:

[0005] Step 1: After the calibration light source is modulated by the time-modulation interferometer and the integrating sphere, a scattered time-domain interference signal is formed, which is used as the incident light source of the interference spectrum imager. Each time the optical path difference of the time-modulation interferometer is changed, the interference spectrum imager collects a stacked interference image.

[0006] Step 2, completing the scanning process of the time modulation interferometer within the specified optical path difference range, and the interference spectrum imager obtains a stacked interference image sequence;

[0007] Step 3, extracting the light intensity signal of each pixel from the stacked interference image sequence, and forming a time-domain discrete interference signal according to the acquisition time sequence;

[0008] Step 4, performing Fourier transform on the discrete time domain interference signal of each pixel to obtain the spectral signal of the corresponding pixel;

[0009] Step 5: extract the signals of the same spectral channel of all pixels to form a single-band image. Since the interference spectral imager itself has interference modulation associated with the field of view, the single-band image has spatial interference fringes.

[0010] Step 6, extracting the interference signal of the single-band image along the field-of-view associated optical path difference modulation dimension, performing Fourier transform on it, obtaining the wavelength calibration result, and separating the modulation term by frequency domain filtering method, retaining the non-modulation term;

[0011] Step 7, analyzing the non-modulation term of the single-band image, and obtaining the relative spectral response coefficient of the interference spectrum imager according to its non-uniformity distribution;

[0012] Step 8, using the relative spectral response coefficient to correct the modulation term of the single-band image, analyzing the non-uniform distribution of the envelope of the modulation term after correction, and obtaining the interference fringe modulation efficiency coefficient of the interference spectrum imager.

[0013] In the above step 1, the adjustment of the optical path difference of the time modulation interferometer can change the intensity of the scattered time domain interference signal at the exit of the integrating sphere, and the adjustment of the sampling interval of the optical path difference can change the spectral resolution of the calibration process.

[0014] In the above step 2, the optical path difference scanning range of the time modulation interferometer can be dynamically adjusted. According to the band range requirements of each calibration process, the specified optical path difference range of the time modulation interferometer is optimized and adjusted to improve the calibration efficiency.

[0015] The beneficial effects of the present invention are:

[0016] (1) The high-precision quantitative measurement method of the interference spectrometer of the present invention uses the scattered time-domain interference signal jointly generated by the time-modulated interferometer and the integrating sphere as the calibration light source. Compared with the classical calibration light source monochromator, it has the advantages of high light flux and high spectral resolution.

[0017] (2) The high-precision quantitative measurement method of the interference spectrometer of the present invention uses a time-modulated interferometer, and the optical path difference sampling interval and sampling range can be selectively set. Therefore, it has the advantages of adjustable spectral resolution and calibration spectral range, and the time of each calibration test can be optimized.

[0018] (3) The high-precision quantitative measurement method of the interference spectrum imaging instrument of the present invention uses a frequency domain filtering method to separate the modulation terms, which can effectively eliminate the influence of the interference fringes generated by the system to be calibrated itself, and is conducive to improving the calibration accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of the present invention.

[0020] Figure 2 Schematic diagram of the optical path of an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] See also Figure 1 The present invention provides a high-precision quantitative measurement method of an interference spectrum imaging instrument, comprising the following steps:

[0023] Step 1: After the calibration light source is modulated by the time-modulated interferometer and the integrating sphere, a scattered time-domain interference signal is formed, which can be expressed as:

[0024] (1)

[0025] In the above formula is the spectrum of the calibration light source, the wave number range is , for The optical path difference introduced by the time-modulation interferometer is used as the incident light source of the interference spectrum imager. Every time the optical path difference of the time-modulation interferometer is changed, the interference spectrum imager collects a stacked interference image.

[0026] Step 2, complete the scanning process of the time modulation interferometer within the specified optical path difference range, and the interference spectrum imager obtains a stacked interference image sequence, which can be expressed as:

[0027] (2)

[0029] In the above formula is the pixel position, R( ) is the relative spectral response, is the interference fringe modulation efficiency, The optical path difference introduced for the interferometric spectral imager;

[0030] Step 3, extract the light intensity signal of each pixel from the stacked interference image sequence, and form a time-domain discrete interference signal according to the acquisition time sequence, which can be expressed as:

[0031] (3)

[0032] Step 4: Perform Fourier transform on the discrete time domain interference signal of each pixel to obtain the spectral signal of the corresponding pixel, which can be expressed as:

[0033] (4)

[0034] Step 5: Extract the signals of the same spectral channel of all pixels to form a single-band image. Since the interference spectral imager itself has field-related interference modulation, the single-band image has spatial interference fringes.

[0035] (5)

[0036] Step 6, extract the interference signal of the single-band image along the field-of-view associated optical path difference modulation dimension (set to the x direction), which can be expressed as:

[0037] (6)

[0038] The above interference signal is Fourier transformed to obtain the wavelength calibration result, and the modulation term and non-modulation term are separated by frequency domain filtering method, where the modulation term is , the non-modulation term is ;

[0039] Step 7: Analyze the non-modulation term of the single-band image and obtain the relative spectral response coefficient of the interference spectrum imager based on its non-uniform distribution. ;

[0040] Step 8: Use the relative spectral response coefficient to correct the modulation term of the single-band image, analyze the non-uniform distribution of the modulation term envelope after correction, and obtain the interference fringe modulation efficiency coefficient of the interference spectrum imager .

[0041] In the above step 1, the adjustment of the optical path difference of the time modulation interferometer can change the intensity of the scattered time domain interference signal at the exit of the integrating sphere, and the adjustment of the sampling interval of the optical path difference can change the spectral resolution of the calibration process.

[0042] In the above step 2, the optical path difference scanning range of the time modulation interferometer can be dynamically adjusted. According to the band range requirements of each calibration process, the specified optical path difference range of the time modulation interferometer is optimized and adjusted to improve the calibration efficiency.

Claims

1. A high-precision quantitative measurement method for an interference spectral imaging instrument, characterized in that: Applicable to the interferometric spectral imaging system, including the following steps: Step 1: After the calibration light source is modulated by the time-modulation interferometer and the integrating sphere, a scattered time-domain interference signal is formed, which is used as the incident light source of the interference spectrum imager. Each time the optical path difference of the time-modulation interferometer is changed, the interference spectrum imager collects a stacked interference image. Step 2, completing the scanning process of the time modulation interferometer within the specified optical path difference range, and the interference spectrum imager obtains a stacked interference image sequence; Step 3, extracting the light intensity signal of each pixel from the stacked interference image sequence, and forming a time-domain discrete interference signal according to the acquisition time sequence; Step 4, performing Fourier transform on the discrete time domain interference signal of each pixel to obtain the spectral signal of the corresponding pixel; Step 5: extract the signals of the same spectral channel of all pixels to form a single-band image. Since the interference spectral imager itself has interference modulation associated with the field of view, the single-band image has spatial interference fringes. Step 6, extracting the interference signal of the single-band image along the field-of-view associated optical path difference modulation dimension, performing Fourier transform on it, obtaining the wavelength calibration result, and separating the modulation term by frequency domain filtering method, retaining the non-modulation term; Step 7, analyzing the non-modulation term of the single-band image, and obtaining the relative spectral response coefficient of the interference spectrum imager according to its non-uniformity distribution; Step 8, using the relative spectral response coefficient to correct the modulation term of the single-band image, analyzing the non-uniform distribution of the envelope of the modulation term after correction, and obtaining the interference fringe modulation efficiency coefficient of the interference spectrum imager.

2. The high-precision relative spectral response calibration method of the interference spectrum imager according to claim 1, characterized in that: Adjusting the optical path difference of the time-modulated interferometer described in step 1 can change the intensity of the scattered time-domain interference signal at the exit of the integrating sphere, and adjusting the sampling interval of the optical path difference can change the spectral resolution of the calibration process.

3. The high-precision relative spectral response calibration method of the interference spectrum imager according to claim 1, characterized in that: The optical path difference scanning range of the time modulation interferometer described in step 2 can be dynamically adjusted. According to the band range requirements of each calibration process, the specified optical path difference range of the time modulation interferometer is optimized and adjusted to improve the calibration efficiency.

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