CN102426163A - Micro-raman spectrum experiment apparatus for adjustable polarization direction continuous collaboration/covariation - Google Patents

Abstract

The invention discloses a micro-Raman spectrum experimental device with continuous coordination of polarization directions and adjustable synergy difference. A micro-Raman spectroscopy system is composed of a laser, an Edge filter, a microscope and a Raman spectrograph, and a polarization synergy/coordination adjustment component is composed of a half-wave plate and a polarizer. The laser light emitted by the laser is reflected by the Edge filter, transmitted by the half-wave plate, and focused on the surface of the measured object by the microscope. The scattered light collected by the microscope is sequentially transmitted through the half-wave plate, Edge filter and polarizer, and then enters the Raman spectrometer to record spectral information. By setting the polarization detection angle of the polarizer to zero or a non-zero value α, the fast optical axis angle of the half-wave plate is adjusted to half of the required rotation angle of the polarization direction, so as to realize the coordination of the polarization directions of the incident and scattered light or the adjustment of the α angle coordination. On the basis of not changing the function and precision of the traditional micro-Raman spectrum experiment system, the invention realizes the modularization and simplification of the polarization synergy and synergy control and reduces the manufacturing cost.

Description

Micro Raman Spectroscopy Experimental Device with Continuous Polarization Direction Synergy and Synergy Adjustable

technical field

The invention belongs to the optical measurement technology, and in particular relates to a micro-Raman spectrum experimental device capable of continuously synergizing and synergistically adjusting the polarization directions of incident light and scattered light.

Background technique

The micro-Raman spectroscopy experimental system generally uses visible, ultraviolet or near-infrared lasers as the excitation light source, and uses the good polarization of the laser to analyze the Raman scattering characteristics of the research object under various combinations of incident light and scattered light polarization directions. It is an important application mode of the micro-Raman spectroscopy experimental system. With the continuous deepening of scientific research and engineering applications, measurement tasks such as quantitative measurement of polarization Raman parameters of crystal materials, estimation of orientation of fiber composite materials, and experimental analysis of microscale plane strain require continuous coordination or synergy in experiments. The adjustment of the polarization direction of incident light and scattered light. Among them, continuous means that the incoming and outgoing polarization directions can be adjusted to any angle (with a period of 0° to 180°); coordinated adjustment means that the incident light and scattered light always keep the same polarization direction when adjusting the incident light and scattered light; synergistic means that Always maintain a fixed angle of difference between the incoming and outgoing polarizations (synergy is a special form of synergy, that is, the angle of synergy is zero).

The current micro-Raman spectroscopy experimental system uses separate control devices for incident and scattered light polarization to realize polarization adjustment. The half-wave plate used to adjust the polarization of the incident light is generally placed in front of the laser exit; the polarizer used to analyze the scattered light is generally installed inside the host of the Raman spectrometer, and unless it is specially customized, there are only two polarizations: horizontal and orthogonal The direction can be manually selected and switched (not continuously adjustable). The incident light first passes through the half-wave plate to adjust the polarization direction, and then enters the surface of the object to be measured, while the scattered light is analyzed by the polarizing plate, and then the spectrum is taken. In the experiment, the polarization direction of incoming and scattered light should be adjusted by manipulating the mechanism of half-wave plate and polarizing plate respectively. Although this method of separate control provides more choices of polarization configurations, it is quite cumbersome for experiments that need to adjust the polarization directions of incoming and scattered light at any time, and it is impossible to adjust the polarization directions continuously, synergistically, or at any angle. . At the same time, the shell of the spectrometer host must be opened to adjust the polarization direction of the scattered light, so repeated operations are likely to bring dust or other debris into the spectrometer, thereby affecting its accuracy and life. The disclosed technologies related to the continuous cooperative adjustment method and device of the Raman spectroscopy experimental system can only realize the coordinated adjustment of incident and scattered polarization, but cannot achieve synergistic adjustment.

Contents of the invention

In view of this, the object of the present invention is to provide a micro-Raman spectroscopy experimental system capable of synergistically or synergistically adjusting the polarization directions of incident and scattered light easily and continuously.

The structural device and technical principles of the present invention will be described below in conjunction with the accompanying drawings. A micro-Raman spectroscopy experimental device with continuous coordination of polarization directions and adjustable synergy, including lasers, Edge filters, half-wave plates, microscopes, polarizers, and Raman spectrographs. The micro-Raman spectroscopy experimental system is composed of laser, Edge filter, microscope and Raman spectrograph. There is a half-wave plate between the Edge filter and the microscope; between the Edge filter and the Raman spectrograph There are polarizers in between. The polarization coordination/coordination adjustment component is composed of a half-wave plate and a polarizer. The laser emitted by the laser is reflected by the Edge filter, transmitted by the half-wave plate, and focused on the surface of the measured object through the microscope. The scattered light from the object to be measured is collected by the microscope and transmitted through the half-wave plate, Edge filter and polarizer in turn, and then enters the Raman spectrograph, and the Raman spectrum information is recorded by the Raman spectrograph. The frequency of laser output from the laser is consistent with the blocking frequency of the Edge filter (as shown in Figure 1). Since the Edge filter and the microscope have no effect on the polarization direction of incident and scattered light, it is not necessary to mark the Edge filter and microscope in Figures 2 and 3.

For experiments that require continuous and coordinated adjustment of the polarization direction of incident light and scattered light: the initial direction of the fast optical axis of the half-wave plate and the polarization analysis direction of the polarizer are set to be parallel to the polarization direction of the laser output from the laser. Observe along the direction of light propagation and take the clockwise direction on the normal plane as positive. When it is necessary to adjust the polarization direction of the incident and scattered light to form an angle θ with the initial direction, it is only necessary to adjust the fast optical axis angle of the half-wave plate ( That is, the angle between the direction of the fast optical axis and the initial direction of the incident light) is adjusted to an angle of θ/2. The angle θ is the angle between the polarization direction of the incident light and the initial direction, the angle θ is from -90° to 90°, and the polarization direction of the scattered light is always parallel to the polarization direction of the incident light.

For experiments that require continuous concordance to adjust the polarization directions of incident light and scattered light (that is, always keep the angle between the polarization directions of incident light and scattered light at a fixed value α): the fast optical axis of the half-wave plate is initially set to be the same as The polarization direction of the laser output laser is parallel. That is, the angle α between the polarization directions of the incident light and the scattered light remains unchanged, and the polarization direction of the polarizer and the polarization direction of the laser output from the laser also form an angle α. α is the included angle between the polarization directions of the incident light and the scattered light, and the α angle is from -90° to 90°. When it is necessary to adjust the covariance of the polarization directions of the incident and scattered light to an angle of θ with their respective initial directions, the angle of the fast optical axis of the half-wave plate must also be adjusted to an angle of θ/2. The definition of angle θ is the same as above.

The working principle of the present invention is as follows: the laser emitted by the laser is initially polarized in the vertical direction on its normal plane, observed along the light propagation direction and taken clockwise on the normal plane as positive. Adjust the direction of the fast optical axis of the half-wave plate to an angle of θ/2 with the initial polarization direction of the incident light, and at the same time adjust the polarization analysis direction of the polarizer to an angle with the initial polarization direction of the incident light, then follow the "along the direction of light propagation Observe and take the rule that clockwise is positive on the normal plane, the angle of the fast axis of the half-wave plate when the incident light passes is θ/2; the angle of the fast axis of the half-wave plate when the returned scattered light passes is -θ /2, and the analysis angle of the polarizer is α. When the incident laser light passes through the half-wave plate, its polarization angle becomes 0+2×(θ/2)=θ, that is, the polarization angle of the incident light when it reaches the measured object is θ (as shown in Figure 2). The incident light continues to travel through the microscope and is incident on the surface of the object to be measured.

The scattered light emitted from the measured object contains polarization in any direction in its normal plane, and can be obtained by orthogonal decomposition to obtain the component with the initial polarization angle of -θ-α and the component with the initial polarization angle of π/2-θ-α , the angles between these two components and the polarization direction of the incident light when it reaches the measured object are α and α-π/2 respectively (as shown in Figure 3). When the scattered light component with a polarization angle of -θ-α passes through the half-wave plate, the angle between the polarization direction and the fast optical axis of the half-wave plate is (-θ/2)-(-θ-α)=θ/2+α , so the polarization angle is rotated to (-θ-α)+2×(θ/2+α)=α, that is, the polarization direction forms an angle α with the initial direction of the incident laser light. When the scattered light component with the polarization angle of π/2-θ-α passes through the half-wave plate, the angle between the polarization direction and the fast optical axis of the half-wave plate is (-θ/2)-(π/2-θ-α) =θ/2+α-π/2, so the polarization angle is rotated to (π/2-θ-α)+2×(θ/2+α-π/2)=α-π/2, that is, the polarization direction It forms an angle of α-π/2 with the initial direction of the incident laser light. It can be seen that after passing through the half-wave plate, the polarization angles of the two scattered light components whose initial polarization angles are -θ-α and π/2-θ-α are transformed into α and α-π/2 respectively.

When the two orthogonally polarized light components pass through the polarizer, the scattered light component with a polarization angle of α is transmitted through and enters the Raman spectrograph because its polarization direction is just parallel to the polarization analysis direction of the polarizer. The component whose polarization angle is α-π/2 is completely blocked because its polarization direction is just perpendicular to the polarization analysis direction of the polarizer. In this way, the scattered light that finally enters the spectrometer is a component with an initial polarization angle of -θ-α, and the included angle between it and the polarization direction of the incident light reaching the surface of the measured object is -θ-(-θ-α)=α. When α=0, no matter what value θ is, the incident light and scattered light are always parallel to each other, realizing cooperative control; when α≠0, no matter what value θ is, the polarization directions of incident light and scattered light are always different by α, thus realizing Synergistic control.

The characteristics and beneficial effects of the present invention are that polarization micro-Raman experiment analysis can be performed according to the requirement of frequent, continuous coordination or synergistic adjustment of the polarization directions of incident light and scattered light. The present invention can utilize the existing micro-Raman spectrum experimental system to be refitted, and without changing the function and precision of the original system, the function of continuously synergizing or synergistically adjusting the polarization of incoming and scattered light is added. Compared with the traditional micro-Raman spectroscopy experimental system, which controls the incident light and scattered light separately, it has the characteristics of simplicity, quickness and modularization. The laser only passes through the polarizer once, and its intensity loss is far smaller than that of the prior art, so it is beneficial to obtain more sufficient spectral information. Using the North filter to replace the Edge filter can not only realize all the functions of the present invention, but also be used for anti-Stokes Raman analysis.

Description of drawings

Fig. 1 is a schematic diagram of the structure and principle of the present invention.

The long broken line in the figure is the incident light, and the short broken line is the scattered light.

Fig. 2 is a schematic diagram of the principle of the incident light part of the present invention.

In the figure: the long broken line is the incident light, the solid arrow indicates the polarization direction of the incident light, the solid arrow in the circle indicates the fast optical axis direction of the half-wave plate, and the θ angle is the angle between the polarization direction of the incident light and the initial direction. Line arrows, solid arrows in circles and θ are observed along the direction of light propagation, and clockwise on the normal plane is taken as positive.

Fig. 3 is a schematic diagram of the principle of the scattered light part of the present invention.

In the figure: the short broken line is the scattered light, the solid arrow indicates the polarization direction of the scattered light, the solid arrow in the circle indicates the fast optical axis direction of the half-wave plate or the polarization analysis direction of the polarizer, and the θ angle indicates the polarization direction of the incident light and The angle between the initial direction, α represents the angle between the polarization direction of the incident light and the scattered light, also known as the covariance angle, the solid arrow, the solid arrow in the circle, θ and α are observed along the direction of light propagation and taken as the method Clockwise on the plane is positive.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments. It should be noted that this embodiment is illustrative rather than restrictive, and does not limit the protection scope of the present invention.

Micro-Raman spectroscopy experimental device with continuous coordination of polarization direction and adjustable synergy difference. In terms of optical path construction and connection: it consists of laser 1, Edge filter 2, microscope 4 and Raman spectrograph 7. Micro-Raman Spectrum Experimental System. A half-wave plate 3 is provided between the Edge filter 2 and the microscope 4; a polarizer 6 is provided between the Edge filter 2 and the Raman spectrograph 7, and the polarization is formed by the half-wave plate 3 and the polarizer 6 Coordinative or polarization coordinating components. The laser light emitted by the laser 1 is reflected by the Edge filter 2, transmitted by the half-wave plate 3, and focused on the surface of the measured object 5 by the microscope 4. The scattered light from the measured object 5 is collected by the microscope 4 and passed through the half-wave plate in turn. 3. The Edge filter 2 and the polarizer 6 enter the Raman spectrograph 7 after transmission, and the Raman spectrum information is recorded by the Raman spectrograph. The laser output frequency of the laser 1 is consistent with the light blocking frequency of the Edge filter 2 . The half-wave plate 3 can be installed between the Edge filter 2 and the microscope 4 , but can also be installed inside the microscope 5 . Edge filter 2 can be replaced by North filter with corresponding blocking frequency.

The experimental requirements for continuously and cooperatively adjusting the polarization directions of incident light and scattered light: the initial direction of the fast optical axis of the half-wave plate 3 and the polarization analysis direction of the polarizer 6 are set to be parallel to the polarization direction of the laser light emitted by the laser 1 . The fast optical axis of the half-wave plate 3 rotates to form an angle θ/2 with the initial direction, and the θ angle is the angle between the polarization direction of the incident light and the initial direction. The θ angle is from -90° to 90°, and the polarization direction of the scattered light is always parallel to the polarization direction of the incident light.

Experimental requirements for adjusting the polarization direction of the incident light and scattered light by synergy: the fast optical axis of the half-wave plate 3 is initially set to be parallel to the polarization direction of the laser light emitted by the laser 1, and the angle between the polarization directions of the incident light and the scattered light is α and kept constant. The polarization analysis direction of the polarizer 6 and the polarization direction of the laser light emitted by the laser 1 also form an angle α, and the angle α is from -90° to 90°. The fast optical axis of the half-wave plate 3 rotates to form an angle of θ/2 with the initial direction, and the θ angle ranges from -90° to 90°, and the polarization direction of the scattered light always maintains an angle α with the polarization direction of the incident light.

Take the experimental test for forward analysis of a single-walled carbon nanotube fiber as an example. The experiment needs to rotate the polarization direction of the incident light and the collected scattered light step by step with a step size of 10° between 0° and 180°, respectively, and measure the polarization direction of the incident light and the collected scattered light at different incident polarization angles (incident light polarization direction and Fiber synergistic and 90° synergistic scattered light Raman spectrum G' intensity and its variation law under fiber direction angle). This experiment is divided into two parts: synergy measurement and synergy measurement.

Co-measurement is performed first. Adjust the fast optical axis direction of the half-wave plate, the analyzing direction of the polarizing plate, and the axial direction of the fiber to be parallel to the initial polarization direction of the laser output from the laser. Adjust the fast optical axis angle of the half-wave plate step by step in the range of 0° to 90° with a step size of 5°, so as to realize the angles of 0°, 10°, 20°, 30°, 40°, 50°, and 60° respectively , 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170° and 180° of incident and scattered light coordinated adjustment. Under the polarization state of each of the above angles, a microscope is used to select random sampling points on the fiber surface, and a Raman spectrograph is used to collect the respective Raman information. The experimental results are shown in Table 1.

A 90° concordance measurement is then performed. Adjust the fast optical axis direction of the half-wave plate and the axial direction of the fiber to be parallel to the initial polarization direction of the laser output laser, and then adjust the polarization analysis direction of the polarizer to be 90° to the initial polarization direction of the laser output laser light. Adjust the fast optical axis angle of the half-wave plate step by step in the range of 0° to 90° with a step size of 5°, so as to realize the angles of 0°, 10°, 20°, 30°, 40°, 50°, and 60° respectively , 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170° and 180° incident and scattered light 90° synergy adjustment. Under the polarization state of each of the above angles, a microscope is used to select random sampling points on the fiber surface and a Raman spectrograph is used to collect the respective Raman information. The experimental results are also shown in Table 1.

Table 1 Experimental data

From the experimental data in Table 1, it can be seen that the G' peak intensity near the 0° direction (0° and 180° are parallel) is absolutely dominant in the co-regulation measurement, while the 90° direction is the weakest; the 90° co-regulation measurement is The intensity of the G' peak in all directions is very weak. Experiments show that in the single-walled carbon nanotube fiber sample, the carbon nanotubes are basically aligned in the same direction.

Claims (6)

1. different adjustable micro Raman spectra experimental provision is worked in coordination with, assisted in the polarization direction continuously; Have laser instrument (1), Edge optical filter (2), half-wave plate (3), microscope (4), polaroid (6) and Raman spectrograph (7); It is characterized in that: form the micro Raman spectra experimental system by laser instrument (1), Edge optical filter (2), microscope (4) and Raman spectrograph (7), between Edge optical filter (2) and microscope (4), be provided with half-wave plate (3); Between Edge optical filter (2) and Raman spectrograph (7), be provided with polaroid (6); Form the collaborative or polarization of polarization by half-wave plate (3) and polaroid (6) and assist different adjusting part; Laser instrument (1) emitting laser passes through Edge optical filter (2) reflection, half-wave plate (3) transmission, is incident on testee (5) surface through microscope (4) focusing; Collect entering Raman spectrograph (7) after the scattered light in testee (5) passes through half-wave plate (3), Edge optical filter (2) and polaroid (6) transmission successively by microscope (4), shoot with video-corder raman spectral information by Raman spectrograph (7).

2., association different adjustable micro Raman spectra experimental provision collaborative continuously according to the described polarization direction of claim 1, it is characterized in that: the frequency of said laser instrument (1) shoot laser and said Edge optical filter (2) resistance light frequency are consistent.

3., association different adjustable micro Raman spectra experimental provision collaborative continuously according to the described polarization direction of claim 1; It is characterized in that: when carrying out continuously the experiment of collaborative adjusting incident light and scatter light polarization direction, the fast axis inceptive direction of said half-wave plate (3) is made as parallel with the polarization direction of said laser instrument (1) shoot laser with the analyzing direction of said polaroid (6); The fast axis of said half-wave plate (3) turns to and inceptive direction θ/2 jiao, and the θ angle is the angle of incident light polarization direction and inceptive direction, and the θ angle is from-90 °～90 °, and the scatter light polarization direction is parallel with the incident light polarization direction all the time.

4., association different adjustable micro Raman spectra experimental provision collaborative continuously according to the described polarization direction of claim 1; It is characterized in that: when assisting the experiment of different adjusting incident light and scatter light polarization direction continuously; The fast axis of said half-wave plate (3) initially is made as parallel with the polarization direction of said laser instrument (1) shoot laser; The angle of incident light and scatter light polarization direction is α and remains unchanged; The polarization direction of the analyzing direction of said polaroid (6) and said laser instrument (1) shoot laser also is the α angle, and the α angle is from-90 °～90 °; Said half-wave plate (3) fast axis turns to and inceptive direction θ/2 jiao, and the θ angle is the angle of incident light polarization direction and inceptive direction, and the θ angle is from-90 °～90 °, and the scatter light polarization direction remains with the incident light polarization direction and is the α angle.

5., association different adjustable micro Raman spectra experimental provision collaborative continuously according to the described polarization direction of claim 1; It is characterized in that said half-wave plate (3) perhaps is installed between said Edge optical filter (2) and the microscope (4), perhaps is installed in said microscope (5) inside.

6., association different adjustable micro Raman spectra experimental provision collaborative continuously according to claim 1 or 2 described polarization directions is characterized in that said Edge optical filter (2) can adopt the North optical filter replacement of corresponding resistance light frequency.

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