A method and apparatus for measuring the angle of Faraday optical rotation

Abstract

The application discloses a Faraday optical rotation deflection angle measuring method and device, which comprises the following steps: setting a quartz glass on the propagation path of the Faraday optical rotation, determining the incident angle of the Faraday optical rotation to the quartz glass, using the quartz glass to gain the actual deflection angle of the Faraday optical rotation, the gain multiple has a corresponding relationship with the incident angle of the Faraday optical rotation to the quartz glass; imaging the Faraday optical rotation after the gain, obtaining an optical rotation image; determining the deflection angle after the gain according to the optical rotation image, and inversely deducing the actual deflection angle of the Faraday optical rotation according to the deflection angle after the gain, the incident angle of the Faraday optical rotation to the quartz glass and the corresponding relationship between the gain multiple and the incident angle of the Faraday optical rotation to the quartz glass. The application can realize reliable measurement of small-angle Faraday optical rotation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of magnetic field measurement, and particularly relates to a Faraday optical rotation deflection angle measurement method and device. BACKGROUND

[0002] Faraday optical rotation is a phenomenon that the polarization plane of polarized light rotates when the polarized light passes through a magneto-optic medium. The magnetic field measurement method based on Faraday effect has been widely applied in Z-pinch experiments and laboratory pulsed power generator astrophysics experiments due to its high spatial resolution and non-invasiveness. One of the main directions of the development of Faraday optical rotation diagnosis in the next stage is how to realize small-angle optical rotation measurement in a low-density magneto-optic medium.

[0003] The existing two-dimensional magnetic field measurement device based on Faraday optical rotation diagnosis mainly adopts a focal plane division amplitude polarimeter and a time-division polarizer. The time-division polarizer acquires high-quality polarization images by setting different angle polarizers in front of the sensor and collecting multiple images, but it is not suitable for scenarios with rapidly changing polarization directions. The focal plane division amplitude polarimeter uses multiple sensors or a region-divided sensor to capture images filtered by polarizers at different angles, so as to realize polarization imaging. This method separates P-polarization and S-polarization by using a polarization beam splitter, and then captures P-polarization and S-polarization by different CCD sensors to determine the linear polarization angle. However, there is still no better measurement method for the deflection angle measurement of small-angle optical rotation generated by a low-density magneto-optic medium. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a Faraday optical rotation deflection angle measurement method and device, which can realize reliable measurement of small-angle Faraday optical rotation.

[0005] In order to solve the above technical problems, the present application is implemented by the following technical solutions:

[0006] According to a first aspect of the present application, a Faraday optical rotation deflection angle measurement method is provided, comprising:

[0007] A quartz glass is arranged on the propagation path of the Faraday optical rotation, and the incident angle of the Faraday optical rotation to the quartz glass is determined. The actual deflection angle of the Faraday optical rotation is amplified by using the quartz glass, and the gain multiple has a corresponding relationship with the incident angle of the Faraday optical rotation to the quartz glass;

[0008] The Faraday optical rotation after amplification is imaged to obtain an optical rotation image;

[0009] The deflection angle after amplification is determined according to the optical rotation image, and the actual deflection angle of the Faraday optical rotation is inversely deduced according to the deflection angle after amplification, the incident angle of the Faraday optical rotation to the quartz glass, and the corresponding relationship between the gain multiple and the incident angle of the Faraday optical rotation to the quartz glass.

[0010] In a possible implementation of the first aspect, the Faraday rotating light is incident on the quartz glass at an angle of 52° to 54°.

[0011] In a possible implementation of the first aspect, the correspondence between the gain factor and the angle of incidence of the Faraday rotating light on the quartz glass is determined by the following method:

[0012] a. deflecting the full P-polarized light at a known angle to obtain simulated rotating light, the deflection angle of the simulated rotating light being the known angle;

[0013] b. directing the simulated rotating light to the quartz glass, and determining the angle of incidence of the simulated rotating light on the quartz glass, the deflection angle of the simulated rotating light being amplified by the quartz glass;

[0014] c. imaging the amplified simulated rotating light to obtain a simulated rotating light image;

[0015] d. determining the deflection angle of the amplified simulated rotating light according to the simulated rotating light image;

[0016] e. determining the relationship between the angle of incidence of the simulated rotating light on the quartz glass and the gain factor according to the known angle and the deflection angle of the amplified simulated rotating light;

[0017] f. repeating b to e for different angles of incidence to obtain a series of relationships between the angle of incidence of the simulated rotating light on the quartz glass and the corresponding gain factor, i.e., the correspondence between the gain factor and the angle of incidence of the Faraday rotating light on the quartz glass.

[0018] In a possible implementation of the first aspect, an anti-reflection film is coated on the incident surface of the quartz glass.

[0019] In a possible implementation of the first aspect, the cross section of the quartz glass is a wedge-shaped surface.

[0020] In a possible implementation of the first aspect, the imaging of the Faraday rotating light with the amplified actual deflection angle is specifically:

[0021] The Faraday rotating light with the amplified actual deflection angle is imaged by a charge-coupled device image sensor with a pixelated polarizer to obtain a rotating light image.

[0022] In a possible implementation of the first aspect, before the gain-amplified deflection angle is determined according to the rotating light image, the method further includes:

[0023] The rotating light image is bilinearly interpolated to complete the spatial resolution.

[0024] In a possible implementation manner of the first aspect, the deflection angle after the gain is determined according to the optical rotation image, in particular:

[0025] The polarization state is determined by analyzing the pixel gray value of the optical rotation image, so as to obtain the Faraday optical rotation deflection angle distribution.

[0026] According to the second aspect of the present application, a Faraday optical rotation deflection angle measuring device is provided, comprising:

[0027] A Faraday optical rotation emitting assembly is configured to generate Faraday optical rotation.

[0028] A quartz glass is arranged on the propagation path of the Faraday optical rotation, and the incident angle of the Faraday optical rotation to the quartz glass is determined, and the quartz glass is configured to gain the actual deflection angle of the Faraday optical rotation, and the gain multiple has a corresponding relationship with the incident angle of the Faraday optical rotation to the quartz glass.

[0029] An optical rotation image imaging assembly is arranged on the propagation path of the Faraday optical rotation reflected by the quartz glass, and is configured to image the Faraday optical rotation after the gain of the actual deflection angle.

[0030] A processing module is configured to determine the deflection angle after the gain according to the optical rotation image, and to inversely deduce the actual deflection angle of the Faraday optical rotation according to the deflection angle after the gain, the incident angle of the Faraday optical rotation to the quartz glass, and the corresponding relationship between the gain multiple and the incident angle of the Faraday optical rotation to the quartz glass.

[0031] In a possible implementation manner of the second aspect, the Faraday optical rotation emitting assembly comprises a beam expander, a half-wave plate, a full-P polarizer, a vacuum chamber and a magneto-optical medium arranged in the vacuum chamber in sequence along the laser propagation path, the laser is converted into full-P polarized light after passing through the full-P polarizer, and the full-P polarized light is converted into Faraday optical rotation after passing through the magneto-optical medium in the vacuum chamber.

[0032] The optical rotation image imaging assembly comprises a convex lens arranged on the propagation path of the Faraday optical rotation reflected by the quartz glass, and a charge coupled device image sensor carrying a pixelated polarizer arranged behind the convex lens.

[0033] Compared with the prior art, the present application has at least the following beneficial effects:

[0034] The application provides a Faraday optical rotation deflection angle measurement method, which ingeniously uses quartz glass to amplify the deflection angle of Faraday optical rotation, so that the small-angle optical rotation which is originally difficult to measure is amplified, thereby greatly improving the measurement accuracy, and is especially suitable for small-angle optical rotation measurement under low-density magneto-optic medium, and fills the blank of the prior art in this field. By adjusting the angle of the probe light incident on the quartz glass, the gain multiple of the optical rotation angle can be flexibly adjusted, thereby adapting to different experimental conditions and measurement requirements, so that the application can be widely applied to various Faraday optical rotation measurement scenes, including z-pinch experiments, laboratory pulsed power generator astrophysics experiments and the like. The measurement method of the application does not depend on a complex polarization imaging system such as a focal plane division amplitude polarimeter or a time-sharing polarizer, but can be realized by using simple quartz glass and imaging technology, which not only simplifies the measurement device and reduces the cost, but also improves the flexibility of measurement, so that it can be applied to more different experimental scenes and conditions. In order to make the above-mentioned purposes, characteristics and advantages of the application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the specific embodiments of the application, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments. Obviously, the drawings described below are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0036] Figure 1 A Faraday optical rotation deflection angle measurement device optical path diagram is provided for the embodiments of the application.

[0037] Figure 2 A pixelated polarizer array is provided for the embodiments of the application.

[0038] Figure 3 A relationship diagram between the incidence angle of the Faraday optical rotation to the quartz glass and the gain multiple is provided for the embodiments of the application.

[0039] 1 is a beam expander; 2 is probe light; 3 is a half-wave plate; 4 is a full-P polarizer; 5 is a vacuum chamber; 6 is a magneto-optic medium; 7 is quartz glass; 8 is a convex lens; 9 is a charge-coupled device image sensor carrying a pixelated polarizer; 10 is a Faraday optical rotation channel; 11 is a 90° polarizer; 12 is a 45° polarizer; 13 is a 135° polarizer; 14 is a 0° polarizer; and 15 is a super-pixel unit. DETAILED DESCRIPTION

[0040] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0041] The embodiment of the present application provides a Faraday optical rotation deflection angle measurement method, which is mainly used to solve the problem that small-angle optical rotation measurement is difficult to realize in the prior art under a low-density magneto-optical medium. The deflection characteristic of quartz glass to light is ingeniously used to enhance the deflection angle of Faraday optical rotation by introducing quartz glass as a gain medium, so that the sensitivity of measurement is improved. The specific process includes the following steps.

[0042] Step 1. Quartz glass is arranged on the propagation path of Faraday optical rotation, and the incident angle of Faraday optical rotation to the quartz glass is determined. The actual deflection angle of Faraday optical rotation is amplified by using the gain of quartz glass, and the gain multiple has a corresponding relationship with the incident angle of Faraday optical rotation to the quartz glass.

[0043] Step 2. The Faraday optical rotation after amplification is imaged to obtain an optical rotation image.

[0044] Step 3. The deflection angle after amplification is determined according to the optical rotation image, and the actual deflection angle of Faraday optical rotation is inversely deduced according to the deflection angle after amplification, the incident angle of Faraday optical rotation to the quartz glass and the corresponding relationship between the gain multiple and the incident angle of Faraday optical rotation to the quartz glass.

[0045] That is, the method amplifies the actual deflection angle of Faraday optical rotation by arranging quartz glass on the propagation path of Faraday optical rotation and using the deflection gain characteristic of quartz glass. Then, the optical rotation image is obtained by imaging technology, and the deflection angle after amplification is determined accordingly. Finally, the actual deflection angle of Faraday optical rotation is inversely deduced by combining the known incident angle, the corresponding relationship between the gain multiple and the incident angle.

[0046] Specifically, the quartz glass is placed on the propagation path of the Faraday rotation, and the incident angle of the Faraday rotation to the quartz glass is accurately measured. The quartz glass produces a deflection gain effect on the incident Faraday rotation, and the gain multiple has a clear correspondence with the incident angle, which is determined by experiment in advance. The Faraday rotation after the gain of the quartz glass is imaged to obtain a rotation image. Through image processing, the deflection angle in the rotation image, i.e., the deflection angle after the gain, is measured. According to the deflection angle after the gain, the incident angle, and the correspondence between the gain multiple and the incident angle. For example, for a Faraday rotation with an actual deflection angle of 2°, an incident angle of 52° is used to enter the quartz glass. It is known that when the incident angle is 52°, the gain of the deflection angle of the Faraday rotation by the quartz glass is 10 times, and the deflection angle after the gain is 20°.

[0047] In an implementable manner, when the quartz glass is arranged, the incident angle of the Faraday rotation to the quartz glass is 52°-54°. Specifically, within this angle range, the quartz glass has a significant gain effect on the deflection angle of the Faraday rotation, and the gain multiple is between 10 times and 22 times, which not only ensures the significant gain of the deflection angle, making the measurement more sensitive and accurate, but also avoids the noise problems such as spontaneous light and scattered light caused by too large gain multiple, thereby improving the signal-to-noise ratio of the measurement.

[0048] Specifically, the gain multiple relationship when the incident angle is 52°-54° is shown in combination with Figure 3 and Table 1.

[0049] Table 1

[0050]

[0051] In an implementable manner, the correspondence between the gain multiple and the incident angle of the Faraday rotation to the quartz glass is determined by the following method:

[0052] a. Deflect the full P-polarized light by a known angle to obtain a simulated rotation, and the deflection angle of the simulated rotation is the known angle.

[0053] That is, the full P-polarized light (i.e., the polarization light parallel to the incident plane) is used as the initial light source. The full P-polarized light is deflected by a known angle to obtain a simulated rotation. The deflection angle of the simulated rotation is the known deflection angle, which is used for subsequent gain multiple calculation.

[0054] b. Shoot the simulated rotation to the quartz glass, and determine the incident angle of the simulated rotation to the quartz glass, and use the quartz glass to gain the deflection angle of the simulated rotation.

[0055] That is, the prepared simulated polarized light is shot to the quartz glass, and the incident angle of the simulated polarized light to the quartz glass is measured. The deflection angle of the simulated polarized light to the quartz glass is amplified by the quartz glass.

[0056] c. The simulated polarized light after amplification is imaged to obtain a simulated polarized light image.

[0057] That is, the simulated polarized light after the deflection angle is amplified is imaged to obtain a simulated polarized light image.

[0058] d. The deflection angle of the simulated polarized light after amplification is determined according to the simulated polarized light image.

[0059] e. The relationship between the incident angle of the simulated polarized light to the quartz glass and the gain multiple is determined according to the known angle and the deflection angle of the simulated polarized light after amplification.

[0060] That is, according to the known angle (i.e. the initial deflection angle of the simulated polarized light) and the deflection angle of the simulated polarized light after amplification, the gain multiple is calculated, which is equal to the deflection angle after amplification divided by the known angle.

[0061] f. For different incident angles, steps b-e are repeated to obtain a series of relationships between the incident angle of the simulated polarized light to the quartz glass and the corresponding gain multiple, that is, the corresponding relationship between the gain multiple and the incident angle of the Faraday polarized light to the quartz glass.

[0062] That is, for different incident angles, the above steps are repeated to obtain a series of relationships between the incident angle of the simulated polarized light to the quartz glass and the corresponding gain multiple. The gain multiple at each incident angle is recorded, and a relationship curve or table between the incident angle and the gain multiple is drawn for quick lookup and application in subsequent measurement.

[0063] In an implementable manner, an anti-reflection film is coated on the incident surface of the quartz glass, which can reduce reflection loss and thus improve the sensitivity of measurement.

[0064] In an implementable manner, the cross section of the quartz glass is a wedge-shaped surface. The design of the wedge-shaped cross section helps to separate the artifacts and avoid the generation of interference fringes, thus improving the accuracy of measurement.

[0065] In an implementable manner, the Faraday polarized light after amplification of the actual deflection angle is imaged, specifically: a charge coupled device image sensor carrying a pixelated polarizer is used to image the Faraday polarized light after amplification of the actual deflection angle to obtain a polarized light image.

[0066] That is, a CCD image sensor with a pixelated polarizer is set behind the quartz glass. The pixelated polarizer is a special filter, each pixel has a different polarization direction, so it can record different polarization components of light at the same time, so that the CCD image sensor can capture the detailed deflection information of the Faraday rotation after the gain of the quartz glass.

[0067] Preferably, as shown in the figure, the super-pixel unit 15 is composed of four pixels with polarization directions of (0°, 45°, 90°, 135°), that is, 90° polarizer 11, 45° polarizer 12, 135° polarizer 13 and 0° polarizer 14. In the CCD image sensor, each adjacent 2x2 pixel region constitutes a super-pixel unit, and by analyzing the gray value in each super-pixel, the state of polarization can be determined. Figure 2

[0068] In an implementation manner, before the deflection angle after the gain is determined according to the rotation image, the method further includes: performing bilinear interpolation on the rotation image to complete the spatial resolution.

[0069] Specifically, bilinear interpolation is a commonly used image scaling and resolution enhancement technique, which calculates the gray value of a new pixel point according to the gray value of adjacent pixel points in the image through linear interpolation, thereby completing the spatial resolution of the image and improving the details and clarity of the image.

[0070] In an implementation manner, the deflection angle after the gain is determined according to the rotation image, specifically: the polarization state is determined by analyzing the pixel gray value of the rotation image, so as to obtain the Faraday rotation deflection angle distribution.

[0071] The Faraday rotation deflection angle measurement method of the application is realized based on the following theoretical basis:

[0072] The Faraday rotation effect refers to the phenomenon that the polarization direction of plane polarized light rotates when passing through a plasma medium (magnetic optical medium) in the presence of a magnetic field, and its formula is as follows:

[0073]

[0074] Wherein is the wavelength of the probe light, L is the path of the probe light beam passing through the plasma medium, B is the magnetic field along the direction of the probe light, n e is the electron density. Therefore, by measuring the Faraday rotation angle distribution, the internal parameter distribution of the plasma can be determined.

[0075] ​For small angle Faraday rotation, it can be detected by a focal plane polarimeter, the pixelated polarizer array is composed of four polarizers with the direction of (0°, 45°, 90°, 135°) relative to the P direction, and each adjacent 2X2 pixel region forms a super-pixel unit. The state of polarization can be determined by analyzing the Stokes components of light in the super-pixel unit, and the specific formula is as follows:

[0076]

[0077]

[0078]

[0079] wherein, is the gray value in the super-pixel unit, represents the angle between the polarization direction of the linearly polarized probe beam and the polarization direction of the 0° pixel unit. However, direct use will cause the image pixel to lose 3 / 4, so the pixel is completed by using bilinear interpolation, and the specific formula is as follows:

[0080]

[0081]

[0082]

[0083] The 0° interpolation gray value at the pixel position (2, 2) is the average gray value of the adjacent four diagonal pixels; the 45° interpolation gray value is the average gray value of the adjacent two vertical pixels, and the 135° interpolation gray value is the average gray value of the adjacent two horizontal pixels. Therefore, the polarization angle of the small angle rotation incident on the camera can be represented by bilinear interpolation. However, when the rotation angle is less than the angular resolution of the camera, the reflectivity ratio between S-polarization and P-polarization must be adjusted by Fresnel reflection. According to the Fresnel equation, we can get:

[0084]

[0085]

[0086] wherein is the refractive index of the two media, are the incident angle and the refracted angle, respectively, is the electric field component corresponding to the polarization direction. According to the law of refraction, we can get:

[0087]

[0088] The sensitivity index is introduced as:

[0089] ​

[0090] The relationship between the sensitivity and the incident angle can be derived by the above formula. When the incident angle is less than the Brewster angle, there is a half-wavelength phase difference between the s-polarized light and the p-polarized light, which causes the rotation direction of the reflected light to be opposite to the Faraday rotation direction. When the incident angle approaches the Brewster angle, the sensitivity increases. However, increasing the sensitivity is not always good, and the spontaneous light plasma needs to be considered as noise.

[0091] In combination Figure 1 As shown in the figure, the embodiment of the present application provides a Faraday optical rotation deflection angle measuring device, which specifically comprises:

[0092] A Faraday optical rotation emitting assembly is configured to generate Faraday optical rotation.

[0093] Preferably, the Faraday optical rotation emitting assembly comprises, in sequence along a laser propagation path, a beam expander 1, a half-wave plate 3, a full P-polarizer 4, a vacuum chamber 5, and a magneto-optical medium 6 arranged in the vacuum chamber 5. After passing through the full P-polarizer 4, the laser is converted into full P-polarized light. After passing through the magneto-optical medium 6 in the vacuum chamber 5, the full P-polarized light is converted into Faraday optical rotation. A full P-polarizer is arranged on the polarization light path before the optical rotation is generated, which ensures that only P-polarized light is generated in the optical rotation, without S-polarized light, so as to prevent the optical rotation deflection angle measurement result from being disturbed.

[0094] Quartz glass is arranged on the propagation path of the Faraday optical rotation, and the incident angle of the Faraday optical rotation to the quartz glass is determined. The quartz glass is configured to amplify the actual deflection angle of the Faraday optical rotation, and the amplification multiple has a corresponding relationship with the incident angle of the Faraday optical rotation to the quartz glass.

[0095] An optical rotation image imaging assembly is arranged on the propagation path of the Faraday optical rotation reflected by the quartz glass, and is configured to image the Faraday optical rotation after the actual deflection angle is amplified.

[0096] Preferably, the optical rotation image imaging assembly comprises a convex lens 8 arranged on the propagation path of the Faraday optical rotation reflected by the quartz glass, and a charge-coupled device image sensor 9 carrying a pixelated polarizer arranged after the convex lens 8.

[0097] A processing module is configured to determine the deflection angle after amplification according to the optical rotation image, and to inversely deduce the actual deflection angle of the Faraday optical rotation according to the deflection angle after amplification, the incident angle of the Faraday optical rotation to the quartz glass, and the corresponding relationship between the amplification multiple and the incident angle of the Faraday optical rotation to the quartz glass.

[0098] Specifically, the probe light 2 emitted by the light source is expanded by the beam expander 1, and then adjusted by the half-wave plate 3 and the full P-polarization plate 4, and then emitted to the quartz glass 8 through the magneto-optical medium 6 in the vacuum chamber 5. Different polarization directions have different reflection ratios, and the gain multiple is adjusted by the rotation angle. The charge-coupled device image sensor 9 with a pixelated polarization plate is used for real-time visible light imaging polarization measurement, and the effect of the Faraday rotation angle of the probe light passing through the magneto-optical medium is multiplied. The laser pulse width is in the order of ns or below, thereby ensuring the time resolution of the measurement.

[0099] Figure 1 The Faraday rotation channel 10 is composed of the quartz glass 7, the convex lens 8, and the charge-coupled device image sensor 9 with a pixelated polarization plate. The polarization direction of the probe light is adjusted to be full P-polarization by the electrically rotating polarization plate. The Faraday rotation causes a small amount of s-polarization of the probe light passing through the magneto-optical medium 6. If the Fresnel reflection has a stronger reflection to s-polarization, the reflected light also has a larger proportion of s-polarization, that is, the Faraday rotation is amplified. The refractive index of the quartz glass 7 is 1.46. When the incident angle is less than the Brewster angle, there is a half-wavelength phase difference between s-polarized light and p-polarized light, which causes the rotation direction of the reflected light to be opposite to the Faraday rotation direction. When approaching the Brewster angle, the sensitivity is increased and imaged to the charge-coupled device image sensor 9 with a pixelated polarization plate through the convex lens 8.

[0100] Figure 2For the pixelated polarization array mounted on the CCD, real-time polarization imaging can be used for Faraday rotation. A super-pixel unit 15 can be composed of four different polarization directions, and the angle between the polarization direction of the linearly polarized probe beam and the polarization direction of the 0° pixel unit of the super-pixel can be obtained by analyzing the gray values of different sensors in the super-pixel. The light intensity of different polarization directions in the super-pixel unit can be regarded as the light intensity after Stokes decomposition, which can completely represent the polarization state of light. At the same time, bilinear interpolation is adopted to ensure that the spatial resolution of the Faraday rotation angle is not lost. In summary, the application provides a Faraday rotation deflection angle measuring device, which separates the sample light beam into the Faraday rotation channel through the quartz glass, and uses the charge coupled device image sensor mounted with the pixelated polarizer to detect the sample light beam rotation polarization angle. The quartz glass beam splitting design can make the current rotation angle multiple controllable and increase by ten times, which can solve the problem of small rotation angle of low-density magneto-optical medium in the existing rotation diagnosis; the charge coupled device image sensor mounted with the pixelated polarizer uses bilinear interpolation method to improve the spatial resolution; the technical scheme of the charge coupled device image sensor mounted with the pixelated polarizer through Fresnel reflection can effectively avoid the image registration limitation of the charge coupled device image sensor mounted with the pixelated polarizer, the optical system structure is compact, the diagnosis data interpretation is simple, and the rotation diagnosis miniaturization is easy to realize, and the environmental adaptability of the rotation diagnosis channel is improved.

[0101] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the skilled person in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0102] Finally, it should be noted that the above-described embodiments are merely specific embodiments of the present application, which are used to illustrate the technical solutions of the present application, but not to limit the same. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that any person skilled in the art can still modify or easily think of changes to the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some of the technical features, within the technical scope disclosed by the present application. The modifications, changes or replacements do not cause the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for measuring the Faraday rotation deflection angle, characterized in that, include: A quartz glass is placed along the propagation path of the Faraday rotation, and the incident angle of the Faraday rotation onto the quartz glass is determined. The actual deflection angle of the Faraday rotation is amplified by the quartz glass, and the gain factor corresponds to the incident angle of the Faraday rotation onto the quartz glass. The correspondence between the gain factor and the incident angle of the Faraday rotation onto the quartz glass is determined using the following method: a. A known angle is used to deflect fully P-polarized light to obtain simulated optical rotation, wherein the deflection angle of the simulated optical rotation is the known angle; b. Point the simulated rotating light towards the quartz glass and determine the incident angle of the simulated rotating light towards the quartz glass. Use the quartz glass to increase the deflection angle of the simulated rotating light. c. Image the amplified simulated optical rotation to obtain a simulated optical rotation image; d. Determine the deflection angle of the simulated optical rotation after gain based on the simulated optical rotation image; e. Based on the known angle and the deflection angle of the simulated optical rotation after gain, determine the relationship between the incident angle of the simulated optical rotation incident on the quartz glass and the gain factor; f. For different incident angles, repeat b~e to obtain a series of relationships between the incident angles of simulated light rotation incident on quartz glass and the corresponding gain factors, that is, to obtain the correspondence between the gain factors and the incident angles of Faraday rotation incident on quartz glass. The Faraday rotation after gain is imaged to obtain an optical rotation image; The deflection angle after gain is determined based on the optical rotation image. Then, based on the deflection angle after gain, the incident angle of the Faraday rotation on the quartz glass, and the correspondence between the gain factor and the incident angle of the Faraday rotation on the quartz glass, the actual deflection angle of the Faraday rotation is deduced. Imaging the Faraday rotation after amplification of the actual deflection angle is performed as follows: An image of the optical rotation is obtained by imaging the Faraday rotation after the actual deflection angle has been amplified using a charge-coupled device image sensor equipped with a pixelated polarizer.

2. The method for measuring the Faraday rotation deflection angle according to claim 1, characterized in that, When setting the quartz glass, the angle of incidence of the Faraday rotation light onto the quartz glass should be 52°~54°.

3. The method for measuring the Faraday rotation deflection angle according to claim 1, characterized in that, An anti-reflective coating is applied to the incident surface of the quartz glass.

4. The method for measuring the Faraday rotation deflection angle according to claim 1, characterized in that, The cross-section of the quartz glass is wedge-shaped.

5. The method for measuring the Faraday rotation deflection angle according to claim 1, characterized in that, Before determining the deflection angle after gain based on the optical rotation image, the following steps are also included: Bilinear interpolation is performed on the optical rotation image to complete the spatial resolution.

6. The method for measuring the Faraday rotation deflection angle according to claim 1, characterized in that, The deflection angle determined based on the gain from the optical rotation image is specifically as follows: The polarization state is determined by analyzing the pixel grayscale values ​​of the optical rotation image, thereby obtaining the distribution of Faraday rotation deflection angle.

7. A device for measuring the Faraday rotation deflection angle, characterized in that, A method for measuring the Faraday rotation deflection angle for implementing any one of claims 1 to 6, comprising: Faraday rotation emission component, used to generate Faraday rotation; Quartz glass is placed in the propagation path of Faraday rotation, and the incident angle of Faraday rotation towards the quartz glass is fixed. The quartz glass is used to increase the actual deflection angle of Faraday rotation, and the gain factor corresponds to the incident angle of Faraday rotation towards the quartz glass. An optical rotation imaging component is positioned on the propagation path of the Faraday rotation after reflection from quartz glass, and is used to image the Faraday rotation after amplification of the actual deflection angle. The processing module is used to determine the deflection angle after gain based on the optical rotation image, and to inversely deduce the actual deflection angle of the Faraday rotation based on the deflection angle after gain, the incident angle of the Faraday rotation on the quartz glass, and the correspondence between the gain factor and the incident angle of the Faraday rotation on the quartz glass.

8. The Faraday rotation deflection angle measuring device according to claim 7, characterized in that, The Faraday rotator emission assembly includes a beam expander (1), a half-wave plate (3), a full P polarizer (4), a vacuum chamber (5), and a magneto-optical medium (6) disposed sequentially along the laser propagation path. The laser light is converted into full P polarized light after passing through the full P polarizer (4), and the full P polarized light is converted into Faraday rotator light after passing through the magneto-optical medium (6) in the vacuum chamber (5). The optical rotation image imaging component includes a convex lens (8) disposed on the propagation path of the Faraday rotation after reflection by quartz glass, and a charge-coupled device image sensor (9) with a pixelated polarizer disposed after the convex lens (8).

Images