A detection device and detection method based on differential Raman technology

Abstract

A detection device and a detection method based on differential Raman technology. The present invention mainly relates to a detection device based on differential Raman technology, and also relates to a detection method based on differential Raman technology. The present invention provides a technical solution to the problem of fluorescence interference in the Raman detection process. The present invention mainly includes a controller, a common optical path narrow line width dual-frequency laser light source with a fixed frequency difference, a common focusing optical path, a common receiving optical path, a common filtering device and a common spectrum detector; the controller is connected to the dual-frequency laser light source and the spectrum detector, and the controller contains a data processing component. The present invention is mainly used in the field of material composition analysis and detection, such as food safety detection.

Description

Technical Field

[0001] The present invention relates to a Raman detection device, in particular to a detection device based on differential Raman technology. The present invention also relates to a detection method based on differential Raman technology. Background Art

[0002] Since the spectral line area of ​​the Raman signal is affected by fluorescence or strong scattering background, the Raman signal in the spectrum is often difficult to distinguish. In the past decade, Raman spectroscopy has attracted more and more attention as a non-contact and on-site method in the field of industrial application process control and environmental monitoring. However, since Raman spectroscopy requires higher excitation energy, focusing on a local part of the material may cause local overheating of the material with a lower softening temperature. Therefore, for materials with dark or fluorescent pigments, ordinary Raman technology cannot effectively obtain the Raman characteristic spectrum of the object being measured.

[0003] Under the same conditions, the Raman shift differential technique uses two laser beams with slight differences to excite the sample and obtain two Raman spectra with equivalent effects. The fluorescence signal hardly changes, while the Raman signal produces a corresponding frequency shift according to the excitation wavelength. Differentiation can effectively overcome fluorescence interference and improve the signal-to-noise ratio of the detection spectrum. In the prior art, the CN105092560A patent discloses a differential Raman spectroscopy device using an external cavity grating tunable laser, but the device requires a complex grating control mechanism. Since the spectral detection method of side reception is adopted, a complex mechanism is required to keep the excitation point and the receiving point coincident, so this solution is difficult to be applied to miniaturized field applications. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a detection device and method based on differential Raman technology, which can effectively obtain the Raman characteristic spectrum of the substance being tested. In order to achieve the technical purpose of the present invention, the present invention provides the following technical solutions:

[0005] The detection device based on differential Raman technology described in the present invention includes a controller, a common optical path narrow linewidth dual-frequency laser light source with a fixed frequency difference, a common focusing optical path, a common receiving optical path, a common filtering device and a common spectrum detector; the controller is connected to the dual-frequency laser light source and the spectrum detector, and the controller contains a data processing component.

[0006] Preferably, the frequency interval of the common optical path narrow linewidth dual-frequency laser light source with a fixed frequency difference is related to the resolution of the selected spectral detector, and its fixed frequency deviation should be greater than the pixel resolution of the spectral detector.

[0007] Preferably, the data processing component mainly includes the required resampling, alignment and differential marking and feature extraction algorithms and databases.

[0008] Preferably, a supporting device is provided in front of the focusing light path for positioning the sample so that the sample spare part area is located in the focal plane of the focusing light path.

[0009] Preferably, the support device includes a support structure outer sleeve and a support structure inner sleeve. The support device has an opaque flexible skirt on the periphery of the contact surface with the sample. When it contacts the sample, it can match the changes in the sample shape and fit the sample surface to form a light-proof dark chamber. The interior of the opaque flexible skirt is a hard limiting structure to ensure that the sample is located near the focal plane of the focusing device.

[0010] A detection method based on differential Raman technology, characterized in that the detection process includes the following steps:

[0011] a Spectral data acquisition: A common optical path narrow linewidth dual-frequency laser light source with a fixed frequency difference alternately illuminates the sample, and the excitation spectrum of the sample is obtained through a shared spectrum detector;

[0012] b Spectral data processing and labeling: The obtained excitation spectra are resampled at equal intervals, and the differential spectra are aligned and differentiated according to the full spectrum signal intensity to achieve differential labeling of the sample molecular features;

[0013] c. De-noising and reconstructing the spectral information according to the differential features, and extracting the height and peak position of the reconstructed characteristic peak as the spectral features;

[0014] d Identification of target materials by matching with a priori database.

[0015] Preferably, since the horizontal coordinate of the original spectrometer data is nonlinear, the spectrum needs to be re-sampled at equal intervals before differentiation, otherwise the filter needs to be nonlinearly processed when the differential feature is demodulated; due to interference from various factors, such as laser bleaching, there may be differences in the non-Raman signals of the sample spectrum measured twice, and direct differentiation may cause a baseline shift in the differential spectrum, which cannot be completely eliminated by controlling the intensity of the excitation light source alone. Therefore, the present invention achieves spectral alignment by performing nonlinear transformation on the spectrum over the entire spectral range.

[0016] The present invention adopts a backward shared Raman optical path and a beam dynamic deflection optical path. In order to further reduce the excitation intensity, a co-output dual-wavelength laser light source is used on the same silicon chip. By alternately exciting the sample and performing subsequent displacement differential Raman processing on the collected spectrum, the stimulated emission interference is eliminated at low input power to obtain the Raman characteristics of the sample. A double-layer support is used to achieve accurate focusing of the sample and isolation of the environmental interference light frequency to overcome fluorescence and other non-Raman interferences, improve the detection sensitivity of the equipment, and thus realize the extraction of the Raman characteristics of the sample of the substance being tested. The material of the test sample is determined by comparing the extracted Raman characteristics with the data in the prior standard library. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a schematic diagram of the structure of a detection device based on differential Raman technology of the present invention.

[0018] Explanation of the numbers in the accompanying drawings: 1-controller, 2-narrow linewidth dual-frequency laser light source, 3-support structure outer sleeve, 4-support structure inner sleeve, 5-focusing mirror, 6-filter, 7-beam splitter, 8-receiving light path, 9-spectral detector. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] The present invention adopts a dual-wavelength laser light source and a multiplexing control system to reduce the volume and weight of the optical system. Since the dual-wavelength light source adopts chip integration, its performance consistency is good, and the dual-wavelength difference can be well maintained, thereby improving the detection stability of the system. The present invention adopts differential detection to achieve low laser input power, and improves the spectral feature recovery capability through the combination of software and hardware. In addition, a double-layer support device is used to ensure that the surface area of ​​the sample coincides with the focal plane of the device through the inner hard limiting layer to obtain the maximum excitation efficiency; at the same time, the support structure is provided with an outer flexible skirt to match the changes in the sample shape, fit the sample surface, and form a light-proof darkroom to prevent interference from ambient light.

[0021] As attached Figure 1As shown, a specific embodiment of a detection device based on differential Raman technology mainly includes a controller 1, a user interaction system, a narrow linewidth dual-frequency laser light source 2, and a spectrum detector 9; in addition, it also includes a multiplexed collimated emission and receiving optical path 8 for outputting and receiving coaxial light beams. In the specific implementation, the sample to be tested is first placed in a supporting device, and the supporting device includes a supporting structure inner sleeve 4 and a supporting structure outer sleeve 3. The supporting device and the sample contact surface are provided with an opaque flexible skirt on the periphery. When it contacts the sample, it can match the sample shape change and fit the sample surface to form a light-proof darkroom. The inside of the opaque flexible skirt is a hard limit structure to ensure that the sample is located near the focal plane of the focusing device. Then, spectral data acquisition is performed, and the dual-frequency laser light source 2 emits excitation light to alternately irradiate the sample. The reflected light of the sample passes through the focusing mirror 5 and then through the spectroscope 7 along the receiving optical path 8 to enter the spectrum detector 9, and the spectrum detector obtains the excitation spectrum of the sample. Then, the obtained spectral data is processed and marked, and the obtained excitation spectrum is resampled at equal intervals. The differential spectrum is obtained and the baseline offset is deducted by the gradient descent algorithm at the same time. The differential spectra are aligned and differentiated according to the full spectrum signal intensity to achieve differential labeling of the sample molecular features. The spectral information is denoised and reconstructed according to the differential features, and the height and peak position of the reconstructed characteristic peaks are extracted as spectral features. Then, the target material is identified by matching the spectral features in the prior database. At the same time, the band fitting filtering method is adopted to design a digital filter to extract only the characteristic signals in the spectrum that are close to the Raman characteristic peak width of the sample and consistent with the differential distance, thereby realizing accurate extraction of Raman features in highly interfering signals.

[0022] The above description is a preferred embodiment of the present invention, but does not limit the present invention. For ordinary technicians in this field, any equivalent substitutions and modifications made to the present invention without departing from the concept and essential features of the present invention should be regarded as within the scope of the present invention.

Claims

1. A detection device based on differential Raman technology, characterized in that: It includes a controller, a common optical path narrow line width dual-frequency laser light source with a fixed frequency difference, a common focusing optical path, a common receiving optical path, a common filtering device and a common spectrum detector; the controller is connected to the dual-frequency laser light source and the spectrum detector, and the controller contains a data processing component; The dual-frequency laser light source emits excitation light to alternately illuminate the sample, and the reflected light of the sample passes through a common filter device and then passes through the common filter device along a common receiving light path to enter the spectrum detector, and the spectrum detector obtains the excitation spectrum of the sample; The common filter device has a support device at the front part thereof, which is used to position the sample so that the sample spare part area is located at the focal plane of the common filter device; The support device comprises a support structure outer sleeve and a support structure inner sleeve. The support device has an opaque flexible skirt on the periphery of the contact surface with the sample. When it contacts the sample, it can match the change of the sample shape and fit the sample surface to form a light-proof darkroom. The interior of the opaque flexible skirt is a hard limiting structure to ensure that the sample is located near the focal plane of the focusing device. The dual-frequency laser light source is integrated on a chip to maintain a dual wavelength difference; The data processing components mainly include the required resampling, alignment and differential marking and feature extraction algorithms and databases.

2. The detection device based on differential Raman technology according to claim 1, characterized in that: The frequency interval of the common optical path narrow line width dual-frequency laser light source with a fixed frequency difference is related to the resolution of the selected spectrum detector, and its fixed frequency deviation should be greater than the pixel resolution of the spectrum detector.

3. A detection method based on the detection device of the differential Raman technology according to claim 1, characterized in that The detection process includes the following steps: a Spectral data acquisition: A common optical path narrow linewidth dual-frequency laser light source with a fixed frequency difference alternately illuminates the sample, and the excitation spectrum of the sample is obtained through a shared spectrum detector; b Spectral data processing and labeling: The obtained excitation spectra are resampled at equal intervals, and the differential spectra are aligned and differentiated according to the full spectrum signal intensity to achieve differential labeling of sample molecular features; c. De-noising and reconstructing the spectral information according to the differential features, and extracting the height and peak position of the reconstructed characteristic peak as the spectral features; d Identification of target materials by matching with a priori database.

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