Raman spectrum detection device for detecting narcotics and dangerous goods

Abstract

The utility model discloses a Raman spectrum detection device for detecting drugs and dangerous goods, which is characterized in that an emission collimating mirror and a dichroscope are sequentially arranged on an emission light path of a laser light source, and a sample to be detected is placed at a focal position of a homogenizing and beam-expanding super lens; a beam expander, a homogenizing and beam-expanding super lens and a beam splitter are sequentially arranged on a reflection light path of a sample to be detected, a first reflection grating and a second reflection grating are respectively arranged on two beam-splitting light paths of the beam splitter, a light filter is arranged on a beam-combining light path of the beam splitter, an imaging super lens is arranged right behind the light filter, and a second reflection grating is arranged on the beam-combining light path of the beam splitter. The detector is located right behind the imaging super lens. According to the utility model, the super lens and the spatial heterodyne Raman spectrometer are innovatively combined, so that non-contact, high-precision and high-flux rapid detection can be realized; the core bottlenecks of low single-point serial acquisition efficiency, mutual restriction of resolution and sensitivity, remarkable environmental noise interference, difficulty in compatibility of large view field and high spatial resolution, low photon utilization rate of complex samples and the like in the traditional Raman spectrum technology are solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of optoelectronic detection, and particularly relates to a high-throughput Raman spectroscopy detection device for drug and hazardous chemical detection. Background Art

[0002] Raman spectroscopy technology is a molecular spectroscopy technology. Its core principle is to obtain molecular vibration and rotation energy level information by analyzing the frequency change (Raman shift) generated by the inelastic scattering of incident light and matter molecules, so as to reveal the structure and chemical bond characteristics of matter. As an important means of molecular fingerprint recognition, Raman spectroscopy technology has an irreplaceable unique value in the field of drug and dangerous goods detection. Raman spectroscopy technology can quickly identify drug components (such as methamphetamine, heroin, ketamine, etc.), provide accurate evidence for the public security organs, and effectively combat drug crimes. Its non-contact detection feature can reduce the risk of law enforcement officers directly contacting drugs and protect personal safety. In addition, through spectral database comparison, the source of drugs can be traced, the production and trafficking chain can be cut off, and cross-border cooperation can be achieved to combat drug crimes. In the detection of hazardous chemicals (such as flammable and explosive solvents, toxic gases), Raman spectroscopy technology can quickly identify the leaked substances, provide real-time data for the accident scene, and guide emergency rescue. For example, in the case of a chemical plant leakage incident, the hazardous chemicals in a transparent container can be detected without opening the box, shortening the response time and reducing environmental pollution and casualties. The detection results of Raman spectroscopy are highly objective and can be used as forensic science evidence to avoid miscarriages of justice caused by errors in manual identification. Its non-destructive detection feature can also preserve the integrity of physical evidence and is suitable for long-term judicial traceability. However, traditional Raman spectroscopy is limited by the single-point scanning mechanism and has three major technical bottlenecks: First, a single measurement only covers a micron-level area, and large-field detection requires mechanical scanning, resulting in low efficiency of dynamic monitoring at the anti-drug scene; Second, when the grating dispersion system improves the resolution by reducing the slit, a large amount of optical flux will be sacrificed, resulting in mutual restriction between the signal-to-noise ratio and the spatial resolution; Third, the precision mechanical scanning components are easily interfered by environmental vibrations and lack stability in complex scenarios such as airport security checks.

[0003] The breakthrough development of Spatial Heterodyne Raman Spectroscopy (SHRS) and micro-optical devices provides a new idea for solving the above bottlenecks. The spatial heterodyne Raman spectrometer realizes full-field parallel acquisition through double-grating interference encoding. Its solid-state design without moving parts (eliminating mirror scanning errors compared with traditional Fourier transform spectrometers) combined with the wavefront modulation ability of the metalens can simultaneously improve the system stability and optical flux. Compared with Fourier transform spectrometers, the SHRS system completely abandons moving parts and uses a solid-state optical design to eliminate mirror scanning errors, and can still maintain ultra-high spectral resolution in on-vehicle mobile detection. The SHRS system based on micro-optics is conducive to realizing portable on-site rapid detection and has important application prospects in the field of drug and dangerous goods detection. Summary of the Invention

[0004] The present invention provides a Raman spectroscopy detection device for drug and dangerous goods detection. Through the innovative combination of a metalens and spatial heterodyne Raman, it can achieve non-contact, high-precision, and high-throughput rapid detection.

[0005] The technical solution of the present invention is a Raman spectroscopy detection device for drug and dangerous goods detection. An emission collimating mirror and a dichroic mirror are sequentially arranged on the emission optical path of a laser light source. The sample to be measured is placed at the focal position of a homogenizing and beam-expanding metalens. A beam expander, a homogenizing and beam-expanding metalens, and a beam splitter are sequentially arranged on the reflection optical path of the sample to be measured. A reflection grating 1 and a reflection grating 2 are respectively arranged on the two beam-splitting optical paths of the beam splitter. A filter is arranged on the combined beam optical path of the beam splitter. An imaging metalens is located directly behind the filter, and a detector is located directly behind the imaging metalens.

[0006] Further, thin nanocylinders with a diameter of 100 nm and a height of 6 - 10 μm and thick nanocylinders with a diameter of 200 nm and a height of 6 - 10 μm are periodically arranged in an alternating pattern on the left side surface of the substrate of the homogenizing and beam-expanding metalens, with a period of 400 - 500 nm; nanocuboid columns with a height of 3 - 5 μm and a side length of 300 - 500 nm are arranged on the right side surface of the substrate of the homogenizing and beam-expanding metalens.

[0007] Further, the conical nano-units of the imaging metalens are arranged in an oriented manner on a strip-shaped substrate with a refractive index of 1.2 - 1.5, with a height of 1 - 2 μm, a cone diameter of 100 - 200 nm, a vertex angle of 30° ± 5°, and a period of 500 nm; strip-shaped substrates with a refractive index of 1.7 - 2.2 and strip-shaped substrates with a refractive index of 1.2 - 1.5 are periodically arranged in an alternating pattern, with a period of 500 - 600 nm.

[0008] The present invention has the following beneficial effects:

[0009] 1. Through the innovative combination of a spatially offset Raman spectrometer and a metalens, the metalens can achieve spot homogenization, beam expansion, and imaging functions, enabling the simultaneous acquisition and analysis of Raman spectra at multiple points on a sample to be measured, and collecting and interfering the Raman scattered light at each point on the sample, thereby realizing high-throughput Raman imaging of large-area samples.

[0010] 2. The high resolution and wide spectral coverage of spatially offset Raman enable more detailed and accurate chemical information to be obtained; in addition, since the entire imaging process is completed in a single measurement, the experimental time is greatly shortened and the work efficiency is improved.

[0011] 3. Based on a metalens and a double reflection grating, the present utility model realizes multi-channel parallel spectral acquisition, breaks through the single-channel detection rate limit, realizes uniform distribution of incident laser light and efficient collection of scattered light, and effectively improves the light energy utilization rate compared with traditional Raman spectroscopy methods; the multi-focus characteristic of the metalens enables large-field-of-view spectral acquisition with a single excitation.

[0012] 4. Spatially offset Raman periodically uses double reflection grating interference and compressive sensing algorithms to convert traditional sequential scanning into spatial frequency encoding, and the full spectral information can be reconstructed through a single exposure.

[0013] 5. The present utility model adopts a fully solid-state design without moving parts, effectively suppresses environmental noise and captures large-angle scattered light, significantly improves the detection efficiency and sensitivity, and solves the key technical problems in the rapid dynamic monitoring, weak signal analysis, and complex environment applications of traditional Raman spectroscopy systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram of the Raman spectroscopy structure;

[0015] Figure 2 is a schematic diagram of the homogenizing and beam-expanding metalens used;

[0016] Figure 3 is a schematic diagram of the structure of the imaging metalens used;

[0017] Figure 4 is the original spectral diagram of the 4-nitrocatechol sample for Raman spectroscopy acquisition;

[0018] Figure 5 is the Raman spectral diagram of the 4-nitrocatechol sample obtained by the inversion algorithm of Raman spectroscopy;

[0019] Description of the reference numerals in the drawings: 1 is a laser light source, 2 is a transmitting collimating mirror, 3 is a dichroic mirror, 4 is a sample to be measured, 5 is a beam expander, 6 is a homogenizing beam expander superlens, 6-1 is a thin nano-cylinder, 6-2 is a thick nano-cylinder, 6-3 is a nano-cuboid column, 6-4 is a substrate; 7 is a first reflection grating, 8 is a beam splitter, 9 is a second reflection grating, 10 is a filter, 11 is an imaging superlens, 11-1 is a conical nano-unit, 11-2 is a high refractive index strip-shaped substrate, 11-3 is a low refractive index strip-shaped substrate, 12 is a detector. Detailed implementation manners

[0020] As Figure 1 shown, a Raman spectroscopy detection device for drug and dangerous goods detection provided in this embodiment includes a laser light source 1, a transmitting collimating mirror 2, a dichroic mirror 3, a beam expander 5, a homogenizing beam expander superlens 6, a first reflection grating 7, a beam splitter 8, a second reflection grating 9, a filter 10, an imaging superlens 11 and a detector 12.

[0021] On the emission optical path of the laser light source 1, a transmitting collimating mirror 2 and a dichroic mirror 3 are arranged in sequence. The sample to be measured 4 is placed at the focal position of the homogenizing beam expander superlens 6. On the reflection optical path of the sample to be measured 4, a beam expander 5, a homogenizing beam expander superlens 6 and a beam splitter 8 are arranged in sequence. A first reflection grating 7 and a second reflection grating 9 are respectively arranged on the two split optical paths of the beam splitter 8. A filter 10 is arranged on the combined optical path of the beam splitter 8. The imaging superlens 11 is located directly behind the filter 10, and the detector 12 is located directly behind the imaging superlens 11.

[0022] In specific implementation, first, an imaging system including a spatial heterodyne Raman spectrometer and a homogenizing beam expander superlens 6 is constructed. The fixed grating of the spatial heterodyne Raman cooperates with the homogenizing beam expander superlens 6, so that the laser emitted by the laser light source 1 becomes parallel light through the transmitting collimating mirror 2 and is incident on the sample to be measured 4 through the dichroic mirror 3. After each point on the sample to be measured 4 is excited by the laser, Raman scattered light is generated; the Raman scattered light is incident on the beam expander 5 through the dichroic mirror 3, and then becomes a uniform parallel light beam through the homogenizing beam expander superlens 6 and is incident on the beam splitter 8, and is divided into two beams of light with a ratio of 50:50, and are respectively incident on the first reflection grating 7 and the second reflection grating 9. After being diffracted by the gratings, they are re-converged on the beam splitter 8, and the Rayleigh scattered light and part of the fluorescence are filtered out through the filter 10, and reach the detector 12 through the imaging superlens 11. The imaging superlens 11 is used to image the Raman light on the detector 27. The detector 27 is a CCD area array, which is used to detect the Raman light and form an interference pattern through the interference effect of the spatial heterodyne Raman. After being processed by the spatial heterodyne Raman spectrometer, the interference pattern is converted into Raman spectral information, thereby realizing the analysis of the chemical composition and structure of each point of the sample to be measured 4.

[0023] The beam splitter 8 is used to split the light from the sample 4 to be measured and the light diffracted and reflected by the beam combining grating.

[0024] Figure 2 This is a schematic diagram of the structure of the homogenized beam expansion super lens 6. The thickness of the substrate 6-4 of the homogenized beam expansion super lens 6 is 2-3 mm, and materials such as silicon, TiO2, and lithium niobate can be used. Fine nano cylinders 6-1 with a diameter of 100 nanometers and a height of 6-10 microns and coarse nano cylinders 6-2 with a diameter of 200 nanometers and a height of 6-10 microns are periodically staggered on the left side of the substrate 6-4 of the homogenized beam expansion super lens 6, with a period of 400-500nm; nano rectangular columns 6-3 with a height of 3-5 microns and a side length of 300-500nm are arranged on the right side of the substrate 6-4 of the homogenized beam expansion super lens 6. Through the nanostructure array of fine nano cylinders 6-1, coarse nano cylinders 6-2, and nano rectangular columns 6-3, the chromatic aberration problem caused by material dispersion of traditional lenses is eliminated. Based on the aspheric phase profile or diffraction optical algorithm, the Gaussian beam is converted into a flat-top distribution, and the incident light is synchronously and precisely controlled. No mechanical moving parts are required, and the optical path stability is high.

[0025] Figure 3 This is a schematic diagram of the structure of the imaging superlens 11. The conical nanounit 11-1 of the imaging superlens 11 is directional and arranged on a strip substrate 11-3 with a refractive index of 1.2-1.5, with a height of 1-2 microns, a cone diameter of 100-200nm, a vertex angle of 30°±5°, and a period of 500nm. The strip substrate 11-2 with a refractive index of 1.7-2.2 and the strip substrate 11-3 with a refractive index of 1.2-1.5 are periodically staggered, with a period of 500-600nm. This design enhances the achromatic performance through the synergistic effect of the sub-wavelength periodic nanostructure, and at the same time uses the directional arrangement characteristics of the conical nanounit 11-1 to achieve polarization selective focusing. The overall structure has an axial gradient refractive index distribution feature, which is suitable for high-resolution imaging; the material of the imaging superlens 11 is titanium dioxide, silicon nitride or amorphous silicon.

[0026] Figure 4 This is the original spectrum of the 4-nitro-o-cresol sample collected by high-throughput Raman spectroscopy. From the figure, we can see the CCD fringe pattern obtained by the spatial heterodyne Raman spectrometer.

[0027] Figure 5 The Raman spectrum of 4-nitro-o-cresol obtained by high-throughput Raman spectroscopy inversion algorithm. It can be seen from the figure that the sample 4 to be tested has a peak at 1250 cm -1 There is a strong Raman peak nearby, and the Raman signal intensity is high and there is no interference, which shows that the use of spatial heterodyne Raman spectrometer combined with superlens can obtain good measurement results.

[0028] In a specific experiment, it is first necessary to precisely calibrate and debug the system to ensure that the laser light source 1 can evenly irradiate the sample to be measured 4, and the homogenizing and beam-expanding metalens 6 can accurately collect the scattered light into the spatial heterodyne Raman system. Next, place the sample to be measured 4 at the focal position of the homogenizing and beam-expanding metalens 6, and ensure that the sample surface is flat and free of impurities. Then, set the working parameters of the spatial heterodyne Raman according to the experimental requirements, such as the spectral range, resolution, etc. During the experiment, it is necessary to continuously monitor the stability and accuracy of the system to ensure the reliability of the experimental results.

[0029] In terms of application scenarios, this device is suitable for security check channels in public places such as airports and subways. It can simultaneously scan multiple target areas and accurately identify drugs (such as methamphetamine, fentanyl) and explosives (such as TNT, ammonium nitrate) hidden in luggage or packages. A single measurement can cover a large field of view, and the detection efficiency is more than 10 times higher than that of traditional devices; in the logistics and customs scenarios, its high-sensitivity characteristics can penetrate transparent packaging to directly analyze liquid or powdered dangerous goods, significantly reducing the need for unpacking inspections and reducing cross-border logistics delays; in the anti-terrorism and emergency response fields, the all-solid-state design without moving parts supports mobile deployment, can detect explosive residues or hazardous chemical leaks in real time, and can distinguish weak Raman signals in complex matrices through compressive sensing algorithms, improving the safety of on-site disposal.

Claims

1. A Raman spectroscopy detection device for drug and dangerous goods detection, characterized in that, On the emission optical path of the laser light source (1), a transmitting collimating mirror (2) and a dichroic mirror (3) are arranged in sequence. The sample to be measured (4) is placed at the focal position of the homogenizing and beam-expanding metalens (6). On the reflection optical path of the sample to be measured (4), a beam expander (5), a homogenizing and beam-expanding metalens (6) and a beam splitter (8) are arranged in sequence. On the two beam-splitting optical paths of the beam splitter (8), a first reflection grating (7) and a second reflection grating (9) are respectively arranged. On the combined beam optical path of the beam splitter (8), a filter (10) is arranged. The imaging metalens (11) is located directly behind the filter (10), and the detector (12) is located directly behind the imaging metalens (11).

2. The Raman spectroscopy detection device for drug and dangerous goods detection according to claim 1, wherein Thin nanocylinders (6-1) with a diameter of 100 nm and a height of 6-10 μm and thick nanocylinders (6-2) with a diameter of 200 nm and a height of 6-10 μm are arranged in a periodic and staggered manner on the left side of the substrate (6-4) of the homogenizing and beam-expanding metalens (6), with a period of 400-500 nm; nanocuboid columns (6-3) with a height of 3-5 μm and a side length of 300-500 nm are arranged on the right side of the substrate (6-4) of the homogenizing and beam-expanding metalens (6).

3. The Raman spectroscopy detection device for drug and dangerous goods detection according to claim 1, characterized in that, The conical nano-units (11-1) of the imaging metalens (11) are arranged in an oriented manner on a strip-shaped substrate (11-3) with a refractive index of 1.2-1.5, with a height of 1-2 μm, a cone diameter of 100-200 nm, a vertex angle of 30°±5°, and a period of 500 nm; strip-shaped substrates (11-2) with a refractive index of 1.7-2.2 and strip-shaped substrates (11-3) with a refractive index of 1.2-1.5 are arranged in a periodic and staggered manner, with a period of 500-600 nm.

Images