Method and device for generating high signal-to-noise ratio spectrum

Abstract

The invention relates to a method and a device for generating a high signal-to-noise ratio spectrum. The method comprises the following steps: selecting a light source to excite a tested sample; capturing an optical signal and generating spectral data, and extracting a light component intensity value corresponding to each wavelength in the spectral data; carrying out convolution on the intensity value and a sine reference signal and a cosine reference signal with the same frequency to obtain an accumulation result of a sine component and a cosine component, and calculating an amplitude value of each wavelength periodically changing along with the excitation signal according to the accumulation result; traversing the spectral data and executing phase locking processing on different light component intensity values to obtain a plurality of amplitude values; and arranging each amplitude value to form a spectrum sequence, and drawing the spectrum sequence into a spectrogram. A phase locking technology is utilized, a captured optical signal and a reference signal with the same frequency are subjected to convolution processing, so that noise approaches to zero, a component which changes with the same frequency of an excitation source in an amplitude time-containing sequence corresponding to a single wavelength is reserved, a noise component with the frequency different from that of the excitation signal is removed, and the signal-to-noise ratio of the signal is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of spectrum measurement, and in particular to a method and device for generating a high signal-to-noise ratio spectrum. Background Art

[0002] At present, spectral analysis is to study the composition and properties of substances by measuring the absorption, reflection, transmission or scattering spectrum of substances to light of different wavelengths. This method is widely used in chemical analysis, physical research, biomedicine and environmental monitoring. For example, in the field of chemical analysis, spectral analysis is used to identify and quantitatively analyze the composition of compounds; in the field of physical research, spectral analysis is used to detect the band structure and electronic state of materials. In the field of biomedicine, spectral analysis is used to detect the spectral characteristics of biological molecules. In the field of environmental monitoring, spectral analysis is used to detect the type and concentration of pollutants.

[0003] In practical applications, spectral analysis has the following problems:

[0004] (1) Spectral signals are easily affected by interference noise, which comes from light source fluctuations, detector thermal noise, electronic circuit interference, and random noise in the environment. This noise will cover useful spectral signals, resulting in a decrease in the signal-to-noise ratio of spectral signals, thereby affecting the accuracy and reliability of spectral analysis.

[0005] (2) Traditional spectrometers rely on direct detection and processing of spectral signals and perform poorly in detecting weak signals or in scenarios with huge noise. For example, if there is a signal at a certain wavelength of the spectral signal and the noise is greater than the signal, the signal at that wavelength is not captured, i.e., the useful signal cannot be effectively extracted. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method and device for generating a high signal-to-noise ratio spectrum to solve one or more problems in the prior art.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A method for generating a high signal-to-noise ratio spectrum comprises the following steps:

[0009] Setting and adjusting the excitation source: Select a periodic light source with adjustable frequency to excite the sample under test;

[0010] Collecting and preprocessing data: capturing optical signals and generating spectrum data, and extracting the intensity value of the light component corresponding to each wavelength in the spectrum data;

[0011] Phase-locked processing: convolve the intensity value with a sine reference signal and a cosine reference signal of the same frequency to obtain the accumulated result of the sine component and the cosine component, and calculate the amplitude value of each wavelength that changes periodically with the excitation signal according to the accumulated result of the sine component and the cosine component;

[0012] Parallel processing: traverse the spectral data and perform phase-locking processing on the intensity values ​​of different light components to obtain multiple amplitude values;

[0013] Spectrum graph generation: each amplitude value is arranged to form a spectrum sequence, and the spectrum sequence is plotted into a spectrum graph.

[0014] Furthermore, the excitation parameters include a phase-locked frequency and a phase-locked cycle number.

[0015] Furthermore, the phase-locked frequency is determined according to the number of sampling points in each cycle, the number of sampling points in each cycle is at least 4, and the number of sampling points in the cycle is a multiple of 4.

[0016] Furthermore, the number of phase-locked cycles is a positive integer.

[0017] Furthermore, the amplitude sequence is convolved with a sinusoidal reference signal of the same frequency, including the following calculation formula:

[0018]

[0019] A1(λ) represents the cumulative result of the sinusoidal component, f(λ,i) represents the intensity of the light component with wavelength λ in the i-th group of data, Represents the sinusoidal reference signal.

[0020] Furthermore, the amplitude sequence is convolved with a sinusoidal reference signal of the same frequency, including the following calculation formula:

[0021]

[0022] A2(λ) represents the cumulative result of the cosine component, f(λ,i) represents the intensity of the light component with wavelength λ in the i-th group of data, Represents the cosine reference signal.

[0023] Furthermore, the amplitude value of each wavelength that changes periodically with the excitation signal includes the following calculation formula:

[0024]

[0025] Wherein A1(λ) represents the accumulation result of the light component of wavelength λ in the sine component, A2(λ) represents the accumulation result of the light component of wavelength λ in the cosine component, and A(λ) represents the amplitude value of the light component of wavelength λ that changes periodically with the excitation signal.

[0026] The present invention also provides a device for generating a high signal-to-noise ratio spectrum method, the device comprising

[0027] An excitation source, wherein the excitation source generates an excitation signal for measurement to excite the sample to be measured, so that the sample to be measured generates a light to be measured having the same frequency as the excitation light source;

[0028] A polychromator, which performs spectroscopic processing on the light to be measured, so as to decompose the light to be measured into monochromatic lights of different wavelengths;

[0029] A charge coupled device, wherein the charge coupled device captures the monochromatic light and converts it into spectral data;

[0030] A microprocessing system is used for phase-locking the spectrum data to obtain the amplitude value of the light component with a wavelength of λ that changes periodically with the excitation signal.

[0031] Furthermore, the microprocessing system includes a calculation module and a signal generation module, wherein the calculation module is used to perform phase-locked calculation on the collected spectral data;

[0032] The signal generating module is used to output a square wave modulated excitation source so that the excitation source periodically modulates the sample under test.

[0033] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0034] By setting the phase-locked frequency, the sampling rate can be kept high during signal processing, so that the periodic changes of the signal can be accurately captured. In addition, according to the set number of phase-locked cycles, it can be ensured that enough data points are collected for phase-locked processing, so that the interference of random noise can be effectively suppressed.

[0035] Furthermore, using phase-locked technology, the captured optical signal is convolved with a sinusoidal reference signal of the same frequency, so that the noise approaches zero, while the component of the amplitude time series corresponding to a single wavelength that changes at the same frequency as the excitation source is retained, thereby effectively removing the noise component that is not in the same frequency as the excitation signal, thereby significantly improving the signal-to-noise ratio of the signal.

[0036] Furthermore, the phase-locked technology can be used to extract the components of the measured signal with the same frequency as the reference signal. The more periodic sampling and period numbers there are, the stronger the noise suppression is and the greater the signal-to-noise ratio is. This method has the advantages of simple, reliable and low-cost measurement.

[0037] Furthermore, the present application utilizes phase-locked technology to improve the anti-interference ability of the device. Since phase-locked technology can suppress non-co-frequency optical information, it can resist sudden strong light interference, sample vibration and even spatial position movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1A flow chart of a method for generating a high signal-to-noise ratio spectrum according to an embodiment of the present invention is shown.

[0039] Figure 2 A schematic structural diagram of a method and device for generating a high signal-to-noise ratio spectrum according to an embodiment of the present invention is shown.

[0040] Figure 3 A schematic diagram of the structure of a microprocessing system in a method and device for generating a high signal-to-noise ratio spectrum according to an embodiment of the present invention is shown.

[0041] Markings in the attached figure: 1. sample to be tested; 2. polychromator; 3. charge coupled device; 4. microprocessing system; 400. computing module; 401. signal generating module; 5. computer; 6. excitation source. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present invention clearer, the following is a further detailed description of a method and device for generating a high signal-to-noise ratio spectrum proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings adopt a very simplified form and all use non-precise proportions, which are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structure, proportion, size, etc. illustrated by the accompanying drawings of this specification are only used to match the content disclosed in the specification, so that people familiar with this technology can understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effect that the present invention can produce and the purpose that can be achieved, should still fall within the scope that the technical content disclosed by the present invention can cover.

[0043] Please refer to Figure 2 , a device for generating a high signal-to-noise ratio spectral method, the device includes an excitation source 6, a polychromator 2, a charge coupled device 3, and a microprocessor system 4.

[0044] Specifically, the excitation source 6 is arranged between the sample to be measured 1 and the microprocessor system 4. The excitation source 6 generates an excitation signal for measurement and excites the sample to be measured 1, that is, it provides light energy to irradiate the sample to be measured 1. The light energy is the starting point of spectral analysis. The light emitted by the excitation source 6 is reflected, absorbed or scattered in the sample to be measured 1, and finally generates the measured light with the same frequency as the excitation source 6.

[0045] Please refer to Figure 3, further, the excitation source 6 is mainly a square wave output by the microprocessor system 4, and the excitation source 6 is periodically modulated to irradiate the sample 1 under test with a specific frequency and intensity. Specifically, the microprocessor system 4 includes a calculation module 400 and a signal generation module 401, and the calculation module 400 and the signal generation module 401 are connected through a first interface. The calculation module 400 is used to perform phase-locked calculation on the collected spectral data (the specific phase-locked calculation process is described in detail in the method), and the signal generation module 401 is used to output a square wave modulated excitation source 6, so that the excitation source 6 periodically modulates the sample 1 under test. At the same time, the calculation module 400 receives a trigger signal or a synchronization signal from the signal generation module 401 through the first interface to ensure the synchronization of spectral data collection and light source excitation. At the same time, the calculation module 400 is also connected to the computer 5 through the second interface to output the result of the phase-locked calculation processing to the display end (such as a display screen) of the computer 5 for display and analysis.

[0046] Furthermore, the signal generating module 401 outputs a periodically changing square wave signal for modulating the light source and stimulating the sample under test. The square wave signal collects N groups of data at equal intervals within one period, and the data are used for subsequent spectral analysis. Specifically, the data includes spectral intensity data, wherein the spectral intensity data reflects the light absorption or emission intensity of the sample under test 1 at different wavelengths.

[0047] Furthermore, the device further comprises a charge coupled device 3, wherein the charge coupled device 3 is electrically connected to the computing module 400 in the microprocessing system 4 via a third interface, and the charge coupled device 3 captures monochromatic light and converts it into spectral data for transmission to the computing module 400. Specifically, the charge coupled device 3 captures the monochromatic light and converts it into an electrical signal. Since the electrical signal is relatively weak, the charge coupled device 3 captures photons and generates a continuous analog signal through the photoelectric effect. Since the computing module 400 ultimately processes a discrete digital signal, it is necessary to convert the analog signal into a digital signal, i.e., spectral data, through analog-to-digital conversion, and the analog-to-digital conversion is achieved through an analog-to-digital converter inside the charge coupled device 3.

[0048] Furthermore, the device also includes a polychromator 2, the output end of the polychromator 2 is connected to the input end of the charge coupled device 3. Since the excitation source 6 contains an optical signal of the obtained sample information, the optical signal enters the incident slit of the polychromator 2. The light from the excitation source 6 entering the polychromator 2 is a vertical line, which is first converted into a parallel light beam by a collimation system. The parallel light beam is dispersed by a dispersion element, that is, it is dispersed according to the wavelength of the light, and finally becomes a horizontal line expanded according to the wavelength after focusing, and is captured by the charge coupled device 3. The charge coupled device 3 reads the charge (converted into voltage) value of each pixel.

[0049] Accordingly, the present invention also provides a method for generating a high signal-to-noise ratio spectrum, comprising the following steps:

[0050] S1: Setting and adjusting the excitation source 6: Selecting a periodic light source with adjustable frequency to excite the sample 1 to be tested. Specifically, the setting of the excitation source parameters includes the following steps:

[0051] S100, phase-locked frequency adjustment: Set the phase-locked frequency according to the requirements to ensure that the frequency selection can cover the response range of the sample 1 under test. At the same time, the phase-locked frequency is determined according to the number of sampling points in each cycle, ensuring that the sampling in the signal processing process is high enough to accurately capture the periodic changes of the signal. Further, the phase-locked frequency is determined according to the number of sampling points in each cycle, the number of sampling points in each cycle is at least 4, and the number of sampling points in the cycle is a multiple of 4, which helps to use the orthogonality of trigonometric functions in subsequent processing for accurate signal separation and extraction.

[0052] S101, intensity adjustment: according to the characteristics of the sample 1 to be tested, the intensity of the light source is set. The intensity is selected to ensure that the sample 1 to be tested can be stimulated to generate a sufficient response signal and to avoid damage to the sample caused by an overly strong light source.

[0053] S102, setting the number of phase-locked cycles, by setting the number of phase-locked cycles, ensuring that the excitation signal is processed after collecting enough data points, thereby effectively suppressing the interference of random noise and effectively removing the noise components of different frequencies of the excitation signal.

[0054] S103, waveform setting: select a suitable waveform for excitation. In this embodiment, square wave excitation is selected. The square wave matches the response characteristics of the sample 1 under test and can be adjusted within the required frequency and intensity range.

[0055] S104, calibrating the light source, calibrating the light source to ensure that the frequency, intensity and waveform of the light source are consistent with the requirements.

[0056] The signal generating module 401 in the microprocessing system 4 outputs a square wave to stimulate the sample 1 under test according to preset parameters.

[0057] S2, captures light signals and generates spectral data; under the excitation of the above-mentioned light source, the excitation source 6 enters the polychromator 2, and the light entering the polychromator 2 passes through the objective lens system. By adjusting the position and width of the slit, light of a certain wavelength (i.e., monochromatic light) can be selectively allowed to pass through and irradiate the charge-coupled device 3. The charge-coupled device 3 is usually placed on the focal plane of the polychromator 2 to receive the monochromatic light after spectral separation. When the monochromatic light irradiates the charge-coupled device 3, the charge of each pixel is read by the charge-coupled device 3 to obtain the light component intensity value corresponding to each wavelength in the spectral data.

[0058] S4, phase-locking processing: convolving the intensity value with a sine reference signal and a cosine reference signal of the same frequency to obtain the accumulation result of the sine component and the cosine component; the specific steps of the phase-locking processing are as follows:

[0059] The amplitude sequence is convolved with a sinusoidal reference signal of the same frequency including the following calculation formula:

[0060]

[0061] A1(λ) represents the cumulative result of the sinusoidal component, f(λ,i) represents the intensity of the light component with wavelength λ in the i-th group of data, Represents the sinusoidal reference signal.

[0062] The amplitude sequence is convolved with a sinusoidal reference signal of the same frequency including the following calculation formula:

[0063]

[0064] A2(λ) represents the cumulative result of the cosine component, f(λ,i) represents the intensity of the light component with wavelength λ in the i-th group of data, Represents the cosine reference signal.

[0065] The amplitude value of each wavelength that changes periodically with the excitation signal includes the following calculation formula:

[0066]

[0067] Wherein A1(λ) represents the accumulation result of the light component of wavelength λ in the sine component, A2(λ) represents the accumulation result of the light component of wavelength λ in the cosine component, and A(λ) represents the amplitude value of the light component of wavelength λ that changes periodically with the excitation signal.

[0068] S5: Parallel processing: Phase-locked processing is performed on the intensity values ​​of the light components corresponding to each wavelength to obtain the amplitude value of each wavelength that changes periodically with the excitation signal. Through parallel processing, multiple tasks can be processed simultaneously, significantly shortening the processing time. At the same time, by accurately analyzing and processing each wavelength, it can not only improve efficiency and generate a spectrum with an improved signal-to-noise ratio, but also more effectively utilize computing resources.

[0069] S6: Spectral graph generation: The amplitude values ​​of each wavelength that changes periodically with the excitation signal are arranged in order of wavelength to form a spectral sequence. The spectral sequence contains the spectral information of the sample 1 under test at different wavelengths, and the spectral sequence is plotted into a spectrogram through drawing software. The spectrogram usually uses wavelength as the horizontal axis and spectral intensity (or amplitude) as the vertical axis. Through the spectrogram, the spectral characteristics of the sample 1 under test at different wavelengths can be intuitively seen.

[0070] The present application utilizes phase-locked technology to improve measurement accuracy while also improving the device's anti-interference capability. Since phase-locked technology can suppress non-co-frequency optical information, it can resist sudden strong light interference, sample vibration, and even spatial position movement.

[0071] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for generating a high signal-to-noise ratio spectrum, characterized in that The following steps are involved: Setting and adjusting the excitation source: Select a periodic light source with adjustable frequency to excite the sample under test; Collecting and preprocessing data: capturing optical signals and generating spectrum data, and extracting the intensity value of the light component corresponding to each wavelength in the spectrum data; Phase-locked processing: convolve the intensity value with a sine reference signal and a cosine reference signal of the same frequency to obtain the accumulated result of the sine component and the cosine component, and calculate the amplitude value of each wavelength that changes periodically with the excitation signal according to the accumulated result of the sine component and the cosine component; Parallel processing: traverse the spectral data and perform phase-locking processing on the intensity values ​​of different light components to obtain multiple amplitude values; Spectrum graph generation: each amplitude value is arranged to form a spectrum sequence, and the spectrum sequence is plotted into a spectrum graph.

2. A method for generating a high signal-to-noise ratio spectrum as claimed in claim 1, characterized in that: The excitation parameters include the phase-locked frequency and the number of phase-locked cycles.

3. A method for generating a high signal-to-noise ratio spectrum as claimed in claim 2, characterized in that: The phase-locked frequency is determined according to the number of sampling points in each cycle, the number of sampling points in each cycle is at least 4, and the number of sampling points in the cycle is a multiple of 4.

4. A method for generating a high signal-to-noise ratio spectrum as claimed in claim 2, characterized in that: The phase-locked period number is a positive integer.

5. A method for generating a high signal-to-noise ratio spectrum as claimed in claim 1, characterized in that: The amplitude sequence is convolved with a sinusoidal reference signal of the same frequency including the following calculation formula: A1(λ) represents the cumulative result of the sinusoidal component, f(λ,i) represents the intensity of the light component with wavelength λ in the i-th group of data, Represents the sinusoidal reference signal.

6. A method for generating a high signal-to-noise ratio spectrum as claimed in claim 1, characterized in that: The amplitude sequence is convolved with a sinusoidal reference signal of the same frequency including the following calculation formula: A2(λ) represents the cumulative result of the cosine component, f(λ,i) represents the intensity of the light component with wavelength λ in the i-th group of data, Represents the cosine reference signal.

7. A method for generating a high signal-to-noise ratio spectrum as claimed in claim 1, characterized in that: The amplitude value of each wavelength that changes periodically with the excitation signal includes the following calculation formula: Wherein A1(λ) represents the accumulation result of the light component of wavelength λ in the sine component, A2(λ) represents the accumulation result of the light component of wavelength λ in the cosine component, and A(λ) represents the amplitude value of the light component of wavelength λ that changes periodically with the excitation signal.

8. A device for generating a high signal-to-noise ratio spectrum according to any one of claims 1 to 7, characterized in that: The device comprises An excitation source, wherein the excitation source generates an excitation signal for measurement to excite the sample to be measured, so that the sample to be measured generates a light to be measured having the same frequency as the excitation light source; A polychromator, which performs spectroscopic processing on the light to be measured, so as to decompose the light to be measured into monochromatic lights of different wavelengths; A charge coupled device, wherein the charge coupled device captures the monochromatic light and converts it into spectral data; A microprocessing system is used for phase-locking the spectrum data to obtain the amplitude value of the light component with a wavelength of λ that changes periodically with the excitation signal.

9. A device for generating a high signal-to-noise ratio spectrum method as claimed in claim 8, characterized in that: The microprocessing system includes a computing module and a signal generating module, wherein The calculation module is used to perform phase-locked calculation on the collected spectral data; The signal generating module is used to output a square wave modulated excitation source so that the excitation source periodically modulates the sample under test.

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