Uniform field Raman detection device

Abstract

A uniform field Raman detection device. The present invention mainly relates to a Raman detection device based on a microlens array, including a parallel monochromatic laser light source, a microlens beam conversion component, a positioning device and a backward Raman spectrum receiving system; wherein the laser emitted by the parallel monochromatic laser light source, after passing through the microlens beam conversion component, forms a uniform light field on the plane determined by the positioning device, and then excites the Raman spectrum of the sample in the detection area, and the backward excited Raman light signal is converted into parallel light by the microlens beam conversion component and enters the backward Raman spectrum receiving system for detection, and finally realizes simultaneous uniform Raman detection of a certain area of ​​the sample. The present invention is mainly to solve the problem of high energy density of the existing Raman excitation light irradiated on the sample point. The technical solution of the present invention can realize uniform Raman detection of the sample, reduce possible damage to the sample, and realize simultaneous detection of a large area.

Description

Technical Field

[0001] The invention relates to the field of Raman spectrum excitation and detection, and in particular to a Raman detection device based on microlens array light beam transformation, which can simultaneously perform uniform excitation and detection on a certain area of ​​a sample. Background Art

[0002] Traditional Raman detection is focused detection, that is, the excitation light needs to be focused on one point, and only the Raman characteristics of that point are collected. This is very convenient for some applications, such as the need to study the cell bodies in natural gemstones. But in many cases, high focusing also brings other problems. For example: burning of the sample. In addition, for the analysis of some non-uniform samples, high focusing is likely to lead to doubts about the insufficient representativeness of the detection spectrum. In order to realize the detection of Raman within a certain range, the prior art 1 (CN20171144267) implements the method of changing the Raman excitation position by a moving device, but this method is limited by the moving device, the detection range and speed are limited, and the moving parts increase the power consumption and failure risk of the equipment; the prior art 2 (CN201621343446) adopts the reflection cavity measurement method, and the loss due to multiple reflections will also increase the loss while realizing large-area Raman detection. Prior art 3 (CN201710104524) is a multi-focus Raman detection device based on a microlens array, which uses microlenses to split the excitation light beam, and uses microlenses to couple Raman signals from different areas of the sample into the optical fiber, and the light beam is shaped into a column through the optical fiber. The spectrometer collects different optical fibers, and then superimposes to achieve selective detection or high-speed detection. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a new technical solution, which transforms a high-intensity parallel excitation beam into a uniform light field through a microlens beam transformation component, and then excites the Raman spectrum of the sample in the detection area, thereby realizing simultaneous uniform Raman detection of a certain area of ​​the sample.

[0004] The present invention provides a uniform field Raman detection device, comprising a parallel monochromatic laser light source, a microlens beam conversion component, a positioning device and a backward Raman spectrum receiving system; the characteristics are that the laser light emitted by the parallel monochromatic laser light source forms a uniform light field on a plane determined by the positioning device after passing through the microlens beam conversion component, and then excites the Raman spectrum of a sample in a detection area, and the backward excited Raman light signal is converted into parallel light by the microlens beam conversion component and enters the backward Raman spectrum receiving system for detection, thereby finally realizing simultaneous uniform Raman detection of a certain area of ​​the sample.

[0005] Furthermore, the microlens beam transformation component is composed of a microlens array or a microlens array group and a focusing lens, and the microlens array is composed of regularly or randomly arranged microlenses.

[0006] Furthermore, the equivalent front focus of the microlens beam transformation component does not form an object-image conjugate relationship with the detection surface. When the parallel light passes through the microlens without considering the interference of the excitation light source, a uniform energy distribution will be formed on the equivalent rear focal plane of the microlens beam transformation component. Considering the interference, the rear focal plane may form a focused spot array with the same energy.

[0007] Furthermore, the positioning device limits the sample to be measured plane to be located at the back focal plane of the focusing lens of the microlens beam transformation assembly, and the limiting method includes physical contact or distance measurement.

[0008] The uniform field Raman detection device of the present invention is composed of a parallel monochromatic laser light source, a microlens beam conversion component, a positioning device and a backward Raman spectrum receiving system. The parallel monochromatic laser can be obtained by collimating and expanding the laser. The parallel excitation light beam passes through the microlens beam conversion component, and forms a uniform light field on the plane determined by the positioning device, and excites the Raman spectrum of the sample in the detection area. The backward excited Raman light signal passes through the microlens beam conversion component in the reverse direction, and is converted into parallel light and enters the backward Raman spectrum receiving system for detection, and finally realizes simultaneous uniform Raman detection of a certain area of ​​the sample. In the uniform field Raman detection device of the present invention, there is a positioning device to limit the sample to be tested The plane is located at the rear focal plane of the focusing lens of the microlens beam conversion component, and the limiting method includes physical contact or ranging. Only the Raman features generated on this plane can all enter the backward Raman spectrum receiving system. In the uniform field Raman detection device described in the present invention, the microlens beam transformation component is composed of a microlens array or a microlens array group and a focusing lens. The first microlens array where the excitation light enters the component is the front of the component, and the excitation light is input in parallel from this, and the reversely received Raman light is output in parallel from this; the side of the component focusing lens facing the sample is the back, and the focal plane corresponding to this surface is defined as the back focal plane of the component, that is, the detection surface. The microlens array is composed of regularly or randomly arranged microlenses. The equivalent front focal point of its microlens beam transformation component (the number is determined by the number of microlenses in the microlens array) does not form an object-image conjugate relationship with the detection surface. When the parallel light passes through the microlens without considering the interference of the excitation light source, a uniform energy distribution will be formed on the equivalent back focal plane of the microlens beam transformation component, as shown in the attached figure. Figure 2As shown in the figure, considering the interference, the back focal plane may form an array of focused light spots with the same energy. Since the energy of the excitation light is dispersed on the detection surface, it will not cause local overheating of the sample and damage the sample. The backward Raman scattering excited by the sample is received by the microlens beam conversion component, and after passing through the focusing lens of the microlens beam conversion component, parallel beams in various directions are formed. These beams will be transformed into parallel light with the same direction through different microlenses, as shown in the figure below. Figure 3 As shown, these parallel lights are received through the slit of the backward Raman spectrum receiving system to realize the surface Raman feature detection of the sample.

[0009] The beneficial effects of the technical solution provided by the present invention are as follows: the present invention adopts a microlens array or a microlens array group to achieve uniform distribution of Raman excitation signal energy on the detection surface, and adopts a common optical path method to receive Raman scattering signals from the surface of the sample to be tested. Compared with the prior art 1, the present invention does not require moving parts and has a simpler structure. Since the energy of the excitation light is dispersed, high energy density will not occur at any time and position, and it is safer to use. Compared with the prior art 2, the present invention has no numerical aperture loss, and has higher receiving efficiency and sensitivity. Compared with the prior art 3, in the prior art, two groups of microlenses and imaging light paths are used to form conjugate points on the surface microregions of the sample to be tested, so as to divide the detection area. However, due to the influence of the numerical aperture of the microlens, the numerical aperture of the Raman signal in the rear part of the junction area is reduced, which will lead to a decrease in receiving efficiency. The present invention only uses one group of microlens arrays to shape the light beam, and has the beneficial technical effect that the front focus of the microlens beam conversion component (corresponding to the optical fiber input end of the prior art 3) and the detection surface do not form an object-image conjugate relationship, and without considering interference, the parallel light will form a uniform distribution on the focal plane behind the output mirror of the microlens beam conversion component after passing through the microlens. The advantages of this design are: 1) the energy distribution of the Raman excitation light field is independent of the energy distribution of the excitation parallel light, which can achieve uniform detection of the sample detection area; 2) during the receiving process, the Raman signals in different directions excited at the same position of the sample can be converted into parallel light through different microlenses, so the receiving numerical aperture of the system will not be compressed, so there is a higher Raman receiving efficiency. The Raman optical path of the present invention is characterized by being unaffected by the energy distribution of the excitation parallel light source, and can evenly expand the excitation light to achieve uniform detection of the sample plane area, which is suitable for samples that require low-energy excitation or non-uniform samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic structural diagram of the uniform field Raman detection device of the present invention.

[0011] Figure 2 Schematic diagram of excitation light dispersion of the uniform field Raman detection device of the present invention.

[0012] Figure 3 The figure is a schematic diagram of Raman signal reception of the uniform field Raman detection device of the present invention.

[0013] Figure 4 It is a schematic diagram of the first embodiment of the uniform field Raman detection device of the present invention.

[0014] Figure 5 It is a schematic diagram of the uniform field Raman detection device of the present invention applied to transparent sample chromatographic detection. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with the accompanying drawings.

[0016] Attached Figure 1 The schematic diagram of the structure of the uniform field Raman detection device of the present invention includes a parallel monochromatic laser light source 2, a microlens beam conversion component 3, a positioning device 4 and a backward Raman spectrum receiving system 1, wherein the backward Raman spectrum receiving system 1 includes a spectroscope. After the parallel excitation light beam emitted by the parallel monochromatic laser light source 2 passes through the microlens beam conversion component 3, a uniform light field is formed on the plane determined by the positioning device 4, and then the Raman spectrum of the sample 5 in the detection area is excited. The backward excited Raman light signal is converted into parallel light by the microlens beam conversion component 3 and enters the backward Raman spectrum receiving system 1 to realize simultaneous uniform Raman detection of a certain area of ​​the sample.

[0017] Attached Figure 2 The schematic diagram of the excitation light dispersion of the uniform field Raman detection device of the present invention includes a microlens beam conversion component 3, a positioning device 4, a sample 5 and an excitation area 6. The incident excitation light passes through the microlens beam conversion component 3 and is uniformly irradiated on the specific excitation area 6 of the sample 5.

[0018] Attached Figure 3 Schematic diagram of Raman signal reception of the uniform field Raman detection device of the present invention. After uniform incident light is irradiated on a certain excitation area 6 of the sample 5, Raman light will be generated. After Raman light in different directions is irradiated on the microlens beam conversion component 3, it will be converted into parallel light.

[0019] Embodiment 1.

[0020] A uniform field Raman detection device, as shown in the attached Figure 4 As shown. The microlens beam transformation component 3 and the entity positioning device 4 are combined into one, with a simple structure and good repeatability, and are suitable for use in portable or handheld Raman detection devices. The positioning device 4 can be a physical positioning ring. When the physical positioning ring contacts the sample plane, the sample plane is the detection surface; at the same time, the physical positioning ring can also block ambient light and improve the signal-to-noise ratio of the detection device. On the other hand, the microlens beam transformation component 3 is composed of two identical microlens arrays and a focusing lens, wherein the second microlens array 8 is located at the focal position of the first microlens array 7, which can effectively improve the uniform light effect of the microlens beam transformation component.

[0021] Embodiment 2.

[0022] As attached Figure 5 As shown, this embodiment performs tomographic detection on the lens sample through an adjustable bracket. The positioning device 4 uses an adjustable bracket to fix the position of the detection device. When the sample 5 is raised or lowered, the sample 5 will gradually pass through the detection surface generated by the microlens beam conversion component 3. Since only the Raman signal of the detection surface can be converted into parallel light and received by the backward Raman receiving system 1, the present invention can realize large-area Raman tomographic detection of transparent samples.

Claims

1. A uniform field Raman detection device, comprising a parallel monochromatic laser light source, a microlens beam conversion assembly, a positioning device and a backward Raman spectrum receiving system; characterized in that: The laser light emitted by the parallel monochromatic laser light source forms a uniform light field on the plane determined by the positioning device after passing through the microlens beam conversion component, and then excites the Raman spectrum of the sample in the detection area. The backward excited Raman light signal is converted into parallel light by the microlens beam conversion component and enters the backward Raman spectrum receiving system for detection, thereby finally realizing simultaneous uniform Raman detection of a certain area of ​​the sample; The microlens beam transformation assembly is composed of a microlens array or a microlens array group and a focusing lens, and the microlens array is composed of regularly or randomly arranged microlenses; The positioning device limits the sample to be measured plane to be located at the back focal plane of the focusing lens of the microlens beam transformation assembly, and the limiting method includes physical contact or distance measurement; The positioning device is a physical positioning ring, and when the physical positioning ring contacts the sample plane, the sample plane becomes the detection surface.

2. The shim Raman detection device according to claim 1, characterized in that: The equivalent front focus of the microlens beam conversion component does not form an object-image conjugate relationship with the detection surface. When the parallel light passes through the microlens without considering the interference of the excitation light source, a uniform energy distribution will be formed on the equivalent rear focal plane of the microlens beam conversion component. Considering the interference, the rear focal plane may form a focused light spot array with the same energy.

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