Multi-wavelength reflective Raman probe and Raman spectrum detection device

Abstract

The invention discloses a multi-wavelength reflective Raman probe and a Raman spectrum detection device. The multi-wavelength reflective Raman probe comprises a first parabolic mirror, a second parabolic mirror, a third parabolic mirror and a fourth parabolic mirror. The first parabolic mirror receives the laser and reflects the laser into a collimated light beam. The second parabolic mirror receives the collimated light beam, converges the collimated light beam and then reflects a convergent light beam. A third mirror surface of the third parabolic mirror is back to the second parabolic mirror, a through hole is formed in the third parabolic mirror, and the convergent light beam passes through the through hole and is focused at a sample detection position. And the third parabolic mirror is positioned between the sample detection part and the second parabolic mirror. The third mirror surface receives the light reflected by the sample detection position and reflects a collimated detection light beam. The fourth parabolic mirror receives the detection light beams and converges the detection light beams into an output light beam, and the output light beam is converged at the focus of the fourth parabolic mirror and finally guided into the spectrograph for analysis. According to the invention, the focusing light spot energy at the sample detection position is effectively dispersed, and the light receiving efficiency is considered.

Description

Technical Field

[0001] The present disclosure relates to a multi-wavelength reflective Raman probe and a Raman spectroscopy detection device, and particularly to a reflective Raman probe that can be used in cooperation with a laser light source and a spectrometer to form a Raman spectroscopy device. The reflective Raman probe is used to receive a laser light source, excite a sample by the laser light source in a reflection manner, and then reflect it to the spectrometer. Background Art

[0002] Traditional microscopic Raman systems adopt an optical design with a single objective lens for light collection and focusing. Therefore, if it is necessary to increase the laser focusing spot, a low-magnification objective lens is often used. However, the low-magnification objective lens has a small numerical aperture (NA), which will affect the collection efficiency of Raman scattered light. On the contrary, when a high-magnification objective lens (with a large NA value) is used, the laser focusing spot will be small, which may lead to the destruction of the object to be measured due to high energy density. In particular, for objects to be measured with an upper limit on the energy density threshold, such as ancient cultural relics, high-energy materials, or plastic SERS substrates (Surface Enhanced Raman Scattering (SERS)), it is easy to cause irreversible damage to the object to be measured or the SERS substrate during measurement, or the Raman spectrum will shift due to heat, affecting the identification result. Summary of the Invention

[0003] The technical problem to be improved by the present disclosure is to provide a multi-wavelength reflective Raman probe and a Raman spectroscopy detection device in view of the deficiencies of the prior art.

[0004] To address the above technical problems, one of the technical solutions adopted in this disclosure is to provide a multi-wavelength reflective Raman probe for receiving laser light, which includes a first parabolic mirror, a second parabolic mirror, a third parabolic mirror, and a fourth parabolic mirror. The first parabolic mirror has a first mirror surface that is designed to focus at a first focal length. The first parabolic mirror receives the laser light and reflects it into a collimated beam. The second parabolic mirror has a second mirror surface that is designed to focus at a second focal length. The second mirror surface faces the first mirror surface to receive the collimated beam. The second mirror surface converges the collimated beam and then reflects a converging beam, which focuses at the focal point of the second focal length. The third parabolic mirror has a third mirror surface that is designed to focus at a third focal length. The third mirror surface faces away from the second mirror surface. The third parabolic mirror forms a through-hole. The converging beam passes through the through-hole. The second focal length exceeds the third mirror surface and focuses at a sample detection location. The third parabolic mirror is located between the sample detection location and the second parabolic mirror. The third mirror surface receives the Raman scattered light reflected from the sample detection location and reflects a collimated detection beam. The fourth parabolic mirror has a fourth mirror surface that is designed to focus at a fourth focal length. The fourth mirror surface receives the detection beam and converges it into an output beam, which focuses at the focal point of the fourth focal length.

[0005] To address the above technical problems, one of the technical solutions adopted in this disclosure is that the multi-wavelength reflective Raman probe further includes a light receiving base located at the focal point of the first focal length for fixing the light source of the laser and allowing the laser to pass through and face the first parabolic mirror.

[0006] To address the above technical problems, one of the technical solutions adopted in this disclosure is that the first focal length is 25.4 millimeters, the second focal length is 50.8 millimeters, the third focal length is 25.4 millimeters, and the fourth focal length is 101.8 millimeters.

[0007] To address the above technical problems, one of the technical solutions adopted in this disclosure is that the multi-wavelength reflective Raman probe further includes a first filter placed between the first parabolic mirror and the second parabolic mirror for suppressing ambient light.

[0008] To address the above technical problems, one of the technical solutions adopted in this disclosure is that the diameter of the through-hole is 3 millimeters to 7 millimeters.

[0009] To improve the above technical problems, one of the technical solutions adopted in this disclosure is that the multi-wavelength reflective Raman probe further includes a third fixed cage, the third parabolic mirror is fixed within the third fixed cage, and the sample detection location abuts against the bottom of the fixed cage.

[0010] To improve the above technical problems, one of the technical solutions adopted in this disclosure is that the multi-wavelength reflective Raman probe further includes a second filter, the second filter is located between the third parabolic mirror and the fourth parabolic mirror, and is used to intercept light within a specific wavelength range.

[0011] To improve the above technical problems, one of the technical solutions adopted in this disclosure is that the multi-wavelength reflective Raman probe further includes a light output seat, the light output seat is fixed at the focus of the fourth focal length, and the light output seat is used to dock with a spectrometer.

[0012] To improve the above technical problems, one of the technical solutions adopted in this disclosure is that the numerical aperture of the third parabolic mirror is greater than the numerical aperture of the fourth parabolic mirror, and the numerical aperture of the fourth parabolic mirror is greater than the numerical aperture of the first parabolic mirror.

[0013] To address the above technical problems, one of the technical solutions adopted in this disclosure is to provide a Raman spectroscopy detection device, which includes a laser light source, a multi-wavelength reflective Raman probe, and a spectrometer. The laser light source provides a laser, and the laser can be configured to have different wavelengths. The multi-wavelength reflective Raman probe includes a first parabolic mirror, a second parabolic mirror, a third parabolic mirror, and a fourth parabolic mirror. The first parabolic mirror has a first mirror surface, and the first mirror surface is designed to focus on a first focal length. The first parabolic mirror receives the laser and reflects the laser into a collimated beam. The second parabolic mirror has a second mirror surface, and the second mirror surface is designed to focus on a second focal length. The second mirror surface faces the first mirror surface to receive the collimated beam. The second mirror surface converges the collimated beam and then reflects a converging beam, and the converging beam focuses at the focal point of the second focal length. The third parabolic mirror has a third mirror surface, and the third mirror surface is designed to focus on a third focal length. The third mirror surface faces away from the second mirror surface. The third parabolic mirror forms a through hole, and the converging beam passes through the through hole. The second focal length exceeds the third mirror surface and focuses on a sample detection location. The third parabolic mirror is located between the sample detection location and the second parabolic mirror. The third mirror surface receives the Raman scattering light reflected from the sample detection location and reflects a collimated detection beam. The fourth parabolic mirror has a fourth mirror surface, and the fourth mirror surface is designed to focus on a fourth focal length. The fourth mirror surface receives the detection beam and converges it into an output beam, and the output beam focuses at the focal point of the fourth focal length. The spectrometer receives the output beam.

[0014] To address the above technical problems, one of the technical solutions adopted in this disclosure is that the Raman spectroscopy detection device further includes a light receiving seat and a light output seat. The light receiving seat is located at the focal point of the first focal length, used to fix the light source of the laser, and allow the laser to pass through and face the first parabolic mirror. The light output seat is fixed at the focal point of the fourth focal length, and the light output seat is used to dock with the spectrometer. The output beam focuses on the light output seat to enter the output optical fiber of the spectrometer.

[0015] To address the above technical problems, one of the technical solutions adopted in this disclosure is that the output optical fiber is a circular-to-linear optical fiber. The output optical fiber has an external fiber end and an internal fiber end. The external fiber end is connected to the light output seat, and the internal fiber end is docked with the spectrometer. The internal fiber bundle of the external fiber end is circularly configured, and the internal fiber bundle of the internal fiber end is linearly configured.

[0016] One of the beneficial effects of the present disclosure is that the multi-wavelength reflective Raman probe provided by the present disclosure uses four parabolic mirrors to effectively disperse the energy of the focused light spot at the sample detection location and take into account the light collection efficiency. Since reflective optical elements are used, there will be no deviation in the spot size and focal plane for the focused light spots of different excitation wavelengths, facilitating the switching and use of different Raman excitation wavelengths. Thereby, the spot size of the converging light beam is adjusted, the collection efficiency is improved, the focused light spot is effectively enlarged, and the light spot energy density is reduced. The reflective parabolic mirror can solve the problem of the focal plane deviation caused by the chromatic aberration of the lens.

[0017] To further understand the features and technical content of the present disclosure, please refer to the following detailed description and drawings related to the present disclosure. However, the provided drawings are only for reference and illustration and are not used to limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of a Raman spectroscopy detection device with a multi-wavelength reflective Raman probe according to the present disclosure;

[0019] Figure 2 is a three-dimensional schematic diagram of the third parabolic mirror according to the present disclosure;

[0020] Figure 3 is a schematic diagram of the configuration of the fiber bundle at the external fiber end of the spectrometer output fiber according to the present disclosure;

[0021] Figure 4 is a schematic diagram of the configuration of the fiber bundle at the internal fiber end of the spectrometer output fiber according to the present disclosure;

[0022] Figure 5 is a statistical line graph of the focused light spot power density and the light collection efficiency of the probe according to the present disclosure;

[0023] Figure 6 is a curve graph of the focal plane position and the beam width at two wavelengths according to the present disclosure.

[0024]

SYMBOL DESCRIPTION

[0025] T1: Light receiving base

[0026] 10: First reflection device

[0027] 10M: First parabolic mirror

[0028] 10f: First focal length

[0029] 11: Cylindrical mirror body

[0030] 12: First mirror surface

[0031] 13: Substrate

[0032] 14: First fixed cage

[0033] 15: First fixed rod

[0034] 20: Second reflecting device

[0035] 20M: Second parabolic mirror

[0036] 20f: Second focal length

[0037] 22: Second mirror surface

[0038] 24: Second fixed cage

[0039] 25: Second connecting rod

[0040] 30: Third reflecting device

[0041] 30M: Third parabolic mirror

[0042] 30f: Third focal length

[0043] 31: Cylindrical mirror body

[0044] 310: Through hole

[0045] 32: Third mirror surface

[0046] 33: Base

[0047] 34: Third fixed cage

[0048] 35: Third connecting rod

[0049] 40: Fourth reflecting device

[0050] 40M: Fourth parabolic mirror

[0051] 40f: Fourth focal length

[0052] 42: Fourth mirror surface

[0053] 44: Fourth fixed cage

[0054] 45: Fourth connecting rod

[0055] T2: Light output seat

[0056] L1: Laser

[0057] L2: Collimated beam

[0058] L3: Converging beam

[0059] L4: Detection beam

[0060] L5: Output beam

[0061] F1: First filter

[0062] F2: Second filter

[0063] 70: Sample stage

[0064] 72: In-and-out mechanism

[0065] 80: Laser light source

[0066] 81: Incident optical fiber

[0067] 90: Spectrometer

[0068] 91: Output optical fiber

[0069] 910: External optical fiber end

[0070] 911: Internal optical fiber end

[0071] 91C: Optical fiber bundle

[0072] S: Sample detection location

[0073] P: Computer Detailed implementation manners

[0074] The following are specific embodiments to illustrate the implementation manners of the "light-emitting device" disclosed in this disclosure. Those skilled in the art can understand the advantages and effects of this disclosure from the content disclosed in this specification. This disclosure can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this disclosure. Additionally, the drawings of this disclosure are only for simple schematic illustration and are not drawn according to actual dimensions, hereby stated in advance. The following implementation manners will further detail the relevant technical content of this disclosure, but the disclosed content is not intended to limit the protection scope of this disclosure.

[0075] It should be understood that although terms such as "first", "second", "third", etc. may be used in this article to describe various elements or signals, these elements or signals should not be limited by these terms. These terms are mainly used to distinguish one element from another element, or one signal from another signal. Additionally, the term "or" used in this article should, depending on the actual situation, possibly include any one or a combination of multiple of the associated listed items.

[0076] Refer to Figure 1As shown, it depicts a schematic diagram of a Raman spectroscopy detection device according to this embodiment. The Raman spectroscopy detection device includes a laser light source 80, a multi-wavelength reflective Raman probe, and a spectrometer 90. The multi-wavelength reflective Raman probe, or simply the reflective Raman probe, is an optical accessory applicable to a Raman spectrometer and is used in conjunction with the laser light source 80 (e.g., a semiconductor laser) and the spectrometer 90. The spectrometer 90 can further calculate and present the Raman spectrum of the sample through a computer P.

[0077] The reflective Raman probe of this embodiment includes a light receiving seat T1, a first parabolic mirror 10M, a second parabolic mirror 20M, a third parabolic mirror 30M, a fourth parabolic mirror 40M, and a light output seat T2.

[0078] The light receiving seat T1, specifically, in this embodiment, is a seat body for positioning the incident optical fiber 81, and the light receiving seat T1 receives the laser of the laser light source 80.

[0079] The first parabolic mirror 10M has a first mirror surface 12. The first mirror surface 12 is a concave parabolic mirror surface. In this embodiment, the first parabolic mirror 10M is an off-axis parabolic mirror (Off Axis Parabolic Mirror, OAP), simply referred to as an off-axis reflector, which includes a cylindrical mirror body 11 and a disc-shaped base 13. The first mirror surface 12 is formed at the end of the cylindrical mirror body 11. The reflecting mirror surface of the off-axis parabolic mirror is a part of a parabolic surface, and the difference from a standard parabolic mirror is that the focus is located outside the optical axis. Based on the principle of the geometric parabolic surface, the off-axis parabolic mirror can focus the parallel incident collimated light beam onto the focus and can also convert the light rays emitted by a point light source into a parallel transmitted light beam. The advantage of using the off-axis parabolic mirror in this embodiment is that it will not generate spherical aberration, chromatic aberration, and can eliminate the phase delay and absorption loss introduced by transmissive optical elements.

[0080] The first mirror surface 12 is planned to be focused on the first focal length 10f. The first parabolic mirror 10M receives the laser L1 and reflects the laser L1 into a collimated light beam L2. For example, the first focal length in this embodiment is 25.4 millimeters, which is 1 inch. The focal length in this embodiment refers to the reflection focal length.

[0081] As Figure 1 shown, the laser L1 is from top to bottom and perpendicular to the optical axis; the collimated light beam L2 is parallel to the optical axis, and the included angle with the incident laser L1 is 90 degrees. In other words, the off-axis angle of the off-axis parabolic mirror in this embodiment is 90 degrees. However, the present disclosure is not limited thereto, and other off-axis angles can also be set for the off-axis parabolic mirror.

[0082] This embodiment further provides a first fixing cage 14 for fixing the first parabolic mirror 10M. The first parabolic mirror 10M, the first fixing cage 14, and other fixing elements can be collectively referred to as the first reflection device 10. The first fixing cage 14 can be cube-shaped, with through-round holes formed on each side and communicating with each other. The fixing cage of this embodiment is convenient for assembly and adjustment, and connecting rods can also be added to each side to connect to other fixing cages or devices.

[0083] Specifically, the light receiving seat T1 of this embodiment is fixed to the first fixing cage 14 through the first fixing rod 15. The light receiving seat T1 is located at the focus of the first focal length 10f and is used to fix the laser light source 80. The laser L1 passes through the light receiving seat T1 and faces the first parabolic mirror 10M. However, this disclosure is not limited to this fixing method. Multiple parabolic mirrors of this disclosure can be fixedly assembled on an integrally formed housing or the same frame.

[0084] The second parabolic mirror 20M has a second mirror surface 22. The second parabolic mirror 20M of this embodiment is also an off-axis parabolic mirror. The second mirror surface 22 is designed to be focused on the second focal length 20f. The second mirror surface 22 receives the above-mentioned collimated beam L2 from the first mirror surface 12, and after converging the collimated beam L2, reflects a converging beam L3, and the converging beam L3 is focused at the focus of the second focal length 20f. The converging beam L3 is perpendicular to the optical axis of the second parabolic mirror 20M. For example, the second focal length of this embodiment is 50.8 millimeters, that is, 2 inches.

[0085] Similarly, this embodiment also provides a second fixing cage 24 for fixing the second parabolic mirror 20M. The second parabolic mirror 20M, the second fixing cage 24, and other fixing elements can be collectively referred to as the second reflection device 20. The structure of the second fixing cage 24 is similar to that of the first fixing cage 14. The second fixing cage 24 and the first fixing cage 14 can be connected to each other by connecting rods. However, this disclosure is not limited to this fixing method. Multiple parabolic mirrors of this disclosure can be fixedly assembled on an integrally formed housing or the same frame.

[0086] It should be further noted that the multi-wavelength reflective Raman probe of this embodiment further includes a first filter F1, which is disposed between the first parabolic mirror 10M and the second parabolic mirror 20M, and can be used to filter out the Raman spectrum caused by the incident optical fiber 81 of the laser light source 80 itself, and also to suppress ambient light. The first filter F1 can be, for example, a laser line filter or a band pass filter.

[0087] The third parabolic mirror 30M has a third mirror surface 32. The third parabolic mirror 30M of this embodiment is also an off-axis parabolic mirror. The third mirror surface 32 is configured to focus on the third focal length 30f. The third mirror surface 32 faces away from the second mirror surface 22, and the second focal length 20f exceeds the third mirror surface 32. For example, the third focal length of this embodiment is 25.4 millimeters, which is 1 inch.

[0088] Similarly, this embodiment also provides a third fixing cage 34 for fixing the third parabolic mirror 30M. The third parabolic mirror 30M, the third fixing cage 34, and other fixing elements can be collectively referred to as the third reflection device 30. The structure of the third fixing cage 34 is similar to that of the first fixing cage 14. The third fixing cage 34 and the second fixing cage 24 can be connected to each other by a plurality of second connecting rods 25. However, the present disclosure is not limited to this fixing method. The plurality of parabolic mirrors of the present disclosure can be fixedly assembled on an integrally formed housing or the same frame.

[0089] Please refer to Figure 2 and Figure 1 , similar to the first parabolic mirror 10M, the third parabolic mirror 30M has a cylindrical mirror body 31 and a disc-shaped base 33. One feature of this embodiment is that the cylindrical mirror body 31 of the third parabolic mirror 30M forms a through hole 310. The through hole 310 passes through the third mirror surface 32 and a circumferential surface of the cylindrical mirror body 31, and the shape of the through hole 310 is generally conical. The diameter of the through hole in this embodiment is 3 millimeters to 7 millimeters. The through hole 310 of this embodiment is perpendicular to the optical axis of the third parabolic mirror 30M and is aligned with the focus of the light beam focused outside the third parabolic mirror 30M.

[0090] As Figure 1 shown, the converging light beam L3 reflected by the second parabolic mirror 20M passes through the above-mentioned through hole 310 and is focused on a sample detection location S. In other words, the sample detection location S is placed at the focus of the third focal length 30f. The sample detection location S is the position where the sample to be detected is placed in this embodiment, and the through hole 310 allows the above-mentioned converging light beam L3 to hit the sample.

[0091] In this embodiment, the sample detection location abuts against the bottom of the third fixing cage 34, and the advantage is that the converging light beam L3 does not exceed the bottom of the third fixing cage 34. The third parabolic mirror 30M is disposed between the sample detection location S and the second parabolic mirror 20M. Since the sample detection location S is located at the focus of the third focal length 30f of the third parabolic mirror 30M, the scattered light generated by the sample detection location S can be reflected by the third mirror surface 32 to produce a collimated detection light beam L4. The detection light beam L4 is directed towards the fourth parabolic mirror 40M.

[0092] For example, the third paraboloid mirror 30M can be made of an aluminum substrate and diamond to reduce the surface roughness and minimize scattering. The third mirror surface 32 of the third paraboloid mirror 30M is preferably coated with a protective gold film, a protective silver film, a protective aluminum film, or a UV-enhanced aluminum film to increase the reflectivity.

[0093] Supplementary note, the sample detection location S of this embodiment can be set on the sample stage 70, and the sample stage 70 can be provided with an in-out mechanism 72. The in-out mechanism 72 can withdraw the sample stage 70 from the third fixed cage 34. After placing the sample to be detected, the in-out mechanism 72 then moves the sample stage 70 to the focal point of the third focal length 30f of the third paraboloid mirror 30M.

[0094] The fourth paraboloid mirror 40M has a fourth mirror surface 42, and the fourth mirror surface 42 is designed to focus on the fourth focal length 40f. The fourth paraboloid mirror 40M of this embodiment is also an off-axis paraboloid mirror. The fourth paraboloid mirror 40M receives the above-mentioned collimated detection beam L4 and converges it into an output beam L5 after reflection by the fourth mirror surface 42. The output beam L5 of this embodiment is focused at the focal point of the fourth focal length 40f. For example, the fourth focal length of this embodiment is 101.8 millimeters.

[0095] Similarly, this embodiment also provides a fourth fixed cage 44 for fixing the fourth paraboloid mirror 40M. The fourth paraboloid mirror 40M, the fourth fixed cage 44, and other fixing elements can be collectively referred to as the fourth reflection device 40. The structure of the fourth fixed cage 44 is similar to that of the first fixed cage 14. The fourth fixed cage 44 and the third fixed cage 34 can be connected to each other by a plurality of third connecting rods 35. However, the present disclosure is not limited to this fixing method. The multiple paraboloid mirrors of the present disclosure can be fixedly assembled on an integrally formed housing or the same frame.

[0096] Supplementary note, this embodiment also includes a second filter F2, and the second filter F2 is located between the third paraboloid mirror 30M and the fourth paraboloid mirror 40M to intercept light within a specific wavelength range. The second filter can be, for example, a notch filter or a long pass filter.

[0097] The multi-wavelength reflective Raman probe of this embodiment further includes a light output seat T2, which is disposed at the focus of the fourth focal length 40f. The light output seat T2 can be fixed, for example, to the fourth reflection device 40 through a fourth connecting rod 45. The light output seat T2 is used to dock with the spectrometer 90. In other words, the output beam L5 is focused on the light output seat T2 to enter the output optical fiber 91 of the spectrometer 90. It should be noted that the output beam L5 of this embodiment is in a circular beam shape. The output optical fiber 91 can be a round-to-linear fiber. Please refer to Figure 3 and Figure 4 , specifically, the output optical fiber 91 has an external optical fiber end 910 and an internal optical fiber end 911. The external optical fiber end 910 is connected to the light output seat T2, and the internal optical fiber end 911 is docked with the spectrometer 90. The cross-sectional optical fiber bundle 91C of the external optical fiber end 910 of the output optical fiber 91 is circularly arranged (circular), and the cross-sectional optical fiber bundle 91C of the internal optical fiber end 911 of the output optical fiber 91 of the spectrometer 90 is linearly arranged (linear) to facilitate docking with the external slit interface of the spectrometer 90 and improve the light collection efficiency.

[0098] For example, there are seven optical fiber bundles 91C inside the output optical fiber 91. The seven optical fiber bundles 91C are arranged in a circular configuration (circular) at the external optical fiber end 910 and in a linear configuration (linear) at the internal optical fiber end 911. The cable of the round-to-linear optical fiber can be used to improve the coupling efficiency between the spectrometer 90 and the light output seat T2. Through this, the linear arrangement better matches the shape of the slit interface of the spectrometer 90 than a single optical fiber or a circular beam configuration, thus increasing the amount of light entering the spectrometer 90.

[0099] Supplementary description: The optical path of the reflective Raman probe in this embodiment is designed to be able to adjust the size of the focus point and the light collection angle range respectively. Specifically, the first parabolic mirror 10M can be an optical element with a relatively small numerical aperture (NA), such as NA = 0.035, which can disperse the excitation energy to a relatively large focused light spot, such as greater than 180 μm, to ensure that the energy per unit area is not too large. In addition, in the light collection part, the third parabolic mirror 30M can have a relatively large numerical aperture (NA greater than 0.35), which can collect the non-directional Raman scattered light more efficiently. Finally, the fourth parabolic mirror 40M is designed to match the light collection angle of the spectrometer 90, such as NA less than 0.22. In other words, the numerical aperture of the third parabolic mirror 30M is greater than that of the fourth parabolic mirror 40M, and the numerical aperture of the fourth parabolic mirror 40M is greater than that of the first parabolic mirror 10M. Then, the above-mentioned circular-to-linear fiber is used for light collection. Thereby, the optical path design of the reflective Raman probe in this embodiment can break away from the limitation of the common optical path for light incidence and light collection in traditional portable Raman optical probes. The reflective Raman probe in this embodiment can disperse the energy to the sample to be detected while maintaining the total incident light energy and a large light collection angle, which can avoid the sample to be detected being damaged due to excessive energy, thereby improving the overall spectral signal intensity.

[0100] [Experimental comparison results]

[0101] Experimental comparison results 1. The experimental comparison between this embodiment and the commercially available dual-wavelength Raman probe (InPhotonics) with reference to patents US6,621,574 and WO2012057875A1 is as follows. The commercially available dual-wavelength Raman probe is internally provided with a non-polarizing beam splitter (NPBS) and a dichroic beam splitter, resulting in a loss of more than half of the incident light efficiency. The dual-wavelength reflective Raman probe in this embodiment improves the optical path traveling mode, and the measured incident light efficiency can be increased from the original 25% to 75%. That is to say, this embodiment can increase the incident light efficiency by 3 times.

[0102] Refer to Figure 5 As shown, the statistical straight line SL1 is the commercially available dual-wavelength Raman probe, and the statistical straight line SL2 is the embodiment of the dual-wavelength reflective Raman probe. Under the condition of the same excitation energy density, the light collection efficiency (output value, unit: counts / sec) of the reflective Raman probe in this embodiment can be increased by 8 times compared with the commercially available Raman probe.

[0103] Experimental comparison results II. For commercially available dual-wavelength Raman probes, due to the use of multiple convex lenses, there are problems such as differences in the size of the focused light spots (30 μm) for two wavelengths (532 nm / 785 nm) and deviations in the focal plane position (0.3 mm). In this embodiment, multiple parabolic mirrors are used, which have the advantages of no spherical aberration, no chromatic aberration, and can eliminate the phase delay and absorption loss introduced by transmissive optical elements. This can solve the above problems. Refer to Figure 6 As shown, for the dual-wavelength reflective Raman probe of this embodiment, the focal plane positions and beam widths (spot sizes) at two wavelengths (532 nm / 785 nm) are both the same.

[0104] [Beneficial effects of the embodiment]

[0105] One of the beneficial effects of this disclosure is that the multi-wavelength reflective Raman probe provided by this disclosure uses four parabolic mirrors to effectively disperse the energy and take into account the light collection efficiency, and there will be no deviation in the focus size and focal plane for the focused light spots of different excitation wavelengths, which is convenient for switching between different Raman excitation wavelengths. Thereby, the size of the light spot of the converging beam is adjusted, the collection efficiency is improved, and the focused light spot is effectively enlarged; the reflective parabolic mirror can solve the problem of focal plane offset caused by chromatic aberration of the lens for different wavelengths.

[0106] Furthermore, the reflective Raman probe developed in this disclosure has the characteristics of low energy density and better light incident and collection efficiencies. The specific advantages are as follows:

[0107] I. Improvement in incident light efficiency: The reflective Raman probe of this embodiment adopts a multi-wavelength common optical path design between the third parabolic mirror and the sample, does not require a beam splitter, reduces the number of optical elements, and can provide better incident light efficiency.

[0108] II. Improvement in light collection efficiency: Under the excitation condition of the same energy density, the light collection efficiency of the reflective Raman probe of this embodiment can be increased by 8 times compared with that of commercially available Raman probes. In other words, for samples to be detected with a low damage threshold, such as SERS substrates, the reflective Raman probe of this disclosure can reduce the damage caused by the photothermal effect, thereby providing better signal intensity.

[0109] III. No chromatic aberration: The beam traveling mode of the reflective Raman probe of this embodiment completely adopts a reflection mode. In the case of multiple wavelengths, the focal plane position and spot size are both the same, and there is no need to refocus when switching wavelengths, which increases the convenience of use.

[0110] IV. Low-energy-density light spot: Through specific experiments, the diameter of the focused light spot of the reflective Raman probe in this embodiment can reach >185 μm, compared with the diameter D = 70 - 100 μm of the focused light spot of a traditional Raman probe or the diameter D < 10 μm of the focused light spot of a microscopic Raman system. Obviously, the unit energy density can be reduced by one to two orders of magnitude, making it less likely to damage the sample to be detected and less likely to cause a Raman spectrum shift in the sample to be detected, thereby affecting the identification result.

[0111] The content disclosed above is only the preferred feasible embodiment of this disclosure, and does not limit the claims of this disclosure. Therefore, all equivalent technical changes made by using the content of this disclosure's specification and drawings are included in the claims of this disclosure.

Claims

1. A multi-wavelength reflective Raman probe for receiving laser light and outputting Raman scattering spectrum signals, characterized in that: include: a first parabolic mirror having a first mirror surface, wherein the first mirror surface is designed to focus at a first focal length, the first parabolic mirror receives the laser, and the laser is reflected by the first mirror surface into a collimated light beam; a second parabolic mirror, having a second mirror surface, the second mirror surface being designed to focus at a second focal length, the second mirror surface facing the first mirror surface to receive the collimated light beam, the second mirror surface converging the collimated light beam and then reflecting a convergent light beam, the convergent light beam being focused at a focus of the second focal length; A third parabolic mirror, having a third mirror surface, the third mirror surface is designed to focus on a third focal length, the third mirror surface is opposite to the second mirror surface, the third parabolic mirror forms a through hole, the convergent light beam passes through the through hole, the second focal length exceeds the third mirror surface, and is focused on a sample detection position, the third parabolic mirror is located between the sample detection position and the second parabolic mirror, the third mirror surface receives the Raman scattered light reflected by the sample detection position and reflects a collimated detection light beam; as well as A fourth parabolic mirror has a fourth mirror surface, the fourth mirror surface is designed to focus on a fourth focal length, the fourth mirror surface receives the detection beam and converges it into an output beam, and the output beam is focused at the focus of the fourth focal length.

2. The multi-wavelength reflective Raman probe according to claim 1, characterized in that: It also includes a light receiving seat, which is located at the focus of the first focal length and is used to fix the light source of the laser and allow the laser to pass through and toward the first parabolic mirror.

3. The multi-wavelength reflective Raman probe according to claim 1, characterized in that: The first focal length is 25.4 mm, the second focal length is 50.8 mm, the third focal length is 25.4 mm, and the fourth focal length is 101.8 mm.

4. The multi-wavelength reflective Raman probe according to claim 1, characterized in that: The invention also includes a first filter, which is placed between the first parabolic mirror and the second parabolic mirror to suppress ambient light.

5. The multi-wavelength reflective Raman probe according to claim 1, characterized in that: The diameter of the through hole is 3 mm to 7 mm.

6. The multi-wavelength reflective Raman probe according to claim 1, characterized in that: It also includes a third fixed cage, the third parabolic mirror is fixed in the third fixed cage, and the sample detection part is in contact with the bottom of the fixed cage.

7. The multi-wavelength reflective Raman probe according to claim 1, characterized in that: It also includes a second filter, which is located between the third parabolic mirror and the fourth parabolic mirror and is used to intercept light within a specific wavelength range.

8. The multi-wavelength reflective Raman probe according to claim 1, characterized in that: It also includes a light output seat, which is fixed at the focus of the fourth focal length and is used for docking with a spectrometer.

9. The multi-wavelength reflective Raman probe according to claim 1, characterized in that: The numerical aperture of the third parabolic mirror is greater than that of the fourth parabolic mirror, and the numerical aperture of the fourth parabolic mirror is greater than that of the first parabolic mirror.

10. A Raman spectrum detection device, characterized in that: include: A laser light source to provide a laser, wherein the laser can be configured to have different wavelengths; A multi-wavelength reflective Raman probe, comprising: a first parabolic mirror having a first mirror surface, wherein the first mirror surface is designed to focus at a first focal length, the first parabolic mirror receives the laser, and the laser is reflected by the first mirror surface into a collimated light beam; a second parabolic mirror, having a second mirror surface, the second mirror surface being designed to focus at a second focal length, the second mirror surface facing the first mirror surface to receive the collimated light beam, the second mirror surface converging the collimated light beam and then reflecting a convergent light beam, the convergent light beam being focused at a focus of the second focal length; a third parabolic mirror, having a third mirror surface, the third mirror surface being designed to focus on a third focal length, the third mirror surface facing away from the second mirror surface, the third parabolic mirror forming a through hole, the convergent light beam passing through the through hole, the second focal length exceeding the third mirror surface and focused on a sample detection location, the third parabolic mirror being located between the sample detection location and the second parabolic mirror, the third mirror surface receiving the Raman scattered light reflected by the sample detection location and reflecting a collimated detection light beam; and a fourth parabolic mirror having a fourth mirror surface, the fourth mirror surface being designed to focus at a fourth focal length, the fourth mirror surface receiving the detection beam and converging it into an output beam, the output beam being focused at a focus of the fourth focal length; and A spectrometer receives the output light beam.

11. The Raman spectrum detection device according to claim 10, characterized in that: Also includes: a light receiving seat, the light receiving seat being located at the focus of the first focal length and used to fix the light source of the laser and allow the laser to pass through and toward the first parabolic mirror; and a light output seat, the light output seat being fixed at the focus of the fourth focal length, and the light output seat being used for docking with the spectrometer; The output light beam is focused on the light output seat to enter the output optical fiber of the spectrometer.

12. The Raman spectrum detection device according to claim 11, characterized in that: The output optical fiber is a circular-to-linear optical fiber, and has an external optical fiber end and an internal optical fiber end. The external optical fiber end is connected to the light output seat, and the internal optical fiber end is connected to the spectrometer. The internal optical fiber bundle of the external optical fiber end is a circular configuration, and the internal optical fiber bundle of the internal optical fiber end is a linear configuration.

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