Faraday sheet performance measurement and polarization imaging system and method

Abstract

The invention provides a Faraday sheet performance measurement and polarization imaging system and method, and relates to the technical field of optical testing. The system comprises a light source system, an optical research platform, a polarizer, a first analyzer, a microscopic imaging system and an image acquisition system, the light source system is used for emitting laser; the optical research platform is used for arranging a to-be-measured Faraday sheet and generating a magnetic field; the microscopic imaging system comprises an eyepiece and an objective lens, and the image acquisition system comprises an image acquisition mechanism; in the first propagation direction of the laser, the light source system, the polarizer, the Faraday piece to be measured, the objective lens, the first polarization analyzer, the eyepiece and the image acquisition mechanism are sequentially arranged. According to the Faraday piece performance measurement and polarized light imaging system, the laser polarization state is accurately controlled, the polarization direction change is accurately detected, and the amplification and focusing functions of a microscopic imaging system are combined, so that the accuracy and comprehensiveness of the performance test of the Faraday piece adopting a magneto-optical film are improved, and the test cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of optical testing, and in particular, to a Faraday sheet performance measurement and polarization imaging system and method. Background Art

[0002] Magneto-optical isolators with Faraday rotator as the core are widely used in laser technology fields such as optical fiber communication, lidar, and optical measurement. They can isolate the reflected light generated from optical fiber connection interfaces, mirrors, etc., solve problems such as noise enhancement and frequency drift caused by the interference of reflected light on the output of the laser light source, and improve the stability of the optical signal and the reliability of the system.

[0003] With the rapid development of global information technology, the laser technology field has an urgent need for miniaturization, modularization, and integration of systems and corresponding components for information reception (collection), processing, and transmission. Correspondingly, compared with the spatial optical path isolator that usually exists in the form of independent components, the waveguide-type optical isolator has the characteristics of smaller size, easier integration, and better reliability, and adapts to the trend of technological development.

[0004] For waveguide-type optical isolators, their Faraday rotators usually use magneto-optical thin films as the core functional layer. The stability and optical properties of the magneto-optical effect of the magneto-optical thin films directly affect the isolation degree, insertion loss, and environmental adaptability of the device. However, due to the small size (millimeter level) and thin thickness (nanometer level) of the magneto-optical thin films, they cannot be ground and polished, and are easily affected by defects such as foreign phases, cracks, grain boundaries, and oxygen vacancies, thereby reducing the magneto-optical effect and increasing the optical loss. Therefore, performance testing is required before application to evaluate the quality of the magneto-optical thin films.

[0005] However, the existing related testing systems are mainly for the Faraday rotator in the magneto-optical isolator in the form of independent components, and have problems such as single function and large measurement error when used to measure magneto-optical thin films. For example, they can only measure the Faraday rotation angle of the magneto-optical thin films, and it is difficult to accurately measure and evaluate the internal defects of the magneto-optical thin film samples. In addition, if further analysis of other characteristics of the magneto-optical thin films is required, characterization techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM) need to be used, resulting in problems such as long testing time and high cost. Summary of the Invention

[0006] The problem solved by the present invention is: how to improve the accuracy and comprehensiveness of the performance testing of the Faraday sheet using magneto-optical thin films and reduce the testing cost.

[0007] To solve the above problems, the present invention provides a Faraday sheet performance measurement and polarization imaging system and method.

[0008] In a first aspect, the present invention provides a Faraday sheet performance measurement and polarization imaging system, comprising a light source system, an optical research platform, a polarizer, a first analyzer, a microscopic imaging system and an image acquisition system; the light source system is used for emitting laser light; the optical research platform is used for arranging the Faraday sheet to be measured and for generating a magnetic field; the microscopic imaging system comprises an eyepiece and an objective lens, and the image acquisition system comprises an image acquisition mechanism; in a first propagation direction of the laser light, the light source system, the polarizer, the Faraday sheet to be measured, the objective lens, the first analyzer, the eyepiece and the image acquisition mechanism are arranged in sequence.

[0009] Optionally, the Faraday sheet performance measurement and polarization imaging system further comprises a first beam splitter and a second beam splitter, the image acquisition system further comprises a first photodetector and a second photodetector, the first beam splitter is arranged between the polarizer and the Faraday sheet to be measured, and the second beam splitter is arranged between the objective lens and the first analyzer; the laser light emitted by the light source system and propagating along the first propagation direction is split by the first beam splitter into a first laser light continuing to propagate along the first propagation direction and a second laser light propagating towards the first photodetector, and the first laser light is split by the second beam splitter into a third laser light continuing to propagate along the first propagation direction and a fourth laser light propagating towards the second photodetector.

[0010] Optionally, the Faraday sheet performance measurement and polarization imaging system further comprises a calculation and imaging system, and the calculation and imaging system is communicatively connected to the image acquisition mechanism, the first photodetector and the second photodetector respectively.

[0011] Optionally, the Faraday sheet performance measurement and polarization imaging system further comprises a lock-in amplifier, both the first photodetector and the second photodetector are communicatively connected to the calculation and imaging system through the lock-in amplifier; and the lock-in amplifier is communicatively connected to the light source system.

[0012] Optionally, the light source system comprises a laser generating mechanism and a tunable filter; in the first propagation direction, the laser generating mechanism, the tunable filter and the polarizer are arranged in sequence.

[0013] Optionally, the Faraday sheet performance measurement and polarization imaging system further comprises a second analyzer arranged between the second beam splitter and the second photodetector, and a rotating stage for rotating the second analyzer; the fourth laser light propagates towards the second photodetector through the second analyzer.

[0014] Optionally, the optical research platform includes a housing, a magnet, and a sample stage. A sample chamber is provided inside the housing, and the magnet and the sample stage are arranged inside the sample chamber. Two oppositely arranged side windows are provided on the side wall of the housing and penetrate through the side wall, and the installation positions of the side windows on the side wall correspond to the sample stage. The sample stage is used to set the Faraday sheet to be measured, and the installation position of the magnet inside the sample chamber corresponds to the sample stage.

[0015] Optionally, the optical research platform further includes a temperature control mechanism arranged inside the sample chamber.

[0016] Optionally, the optical research platform further includes a fixing mechanism detachably connected to the sample stage. The fixing mechanism is provided with a first installation groove for accommodating the Faraday sheet to be measured, and a through hole penetrating through the fixing mechanism is provided at the bottom of the first installation groove.

[0017] In a second aspect, the present invention provides a method for measuring the performance of a Faraday sheet and polarization imaging. Based on the Faraday sheet performance measurement and polarization imaging system as described in the first aspect, the method for measuring the performance of a Faraday sheet and polarization imaging includes:

[0018] Controlling the light source system of the Faraday sheet performance measurement and polarization imaging system to emit laser with a first preset parameter, and finely adjusting the optical path to make the reference signal and the detection signal meet the preset conditions; wherein, the reference signal is the signal obtained by the first photodetector of the image acquisition system of the Faraday sheet performance measurement and polarization imaging system, and the detection signal is the signal obtained by the second photodetector of the image acquisition system.

[0019] Installing the Faraday sheet to be measured onto the optical research platform of the Faraday sheet performance measurement and polarization imaging system.

[0020] Focusing the objective lens of the microscopic imaging system of the Faraday sheet performance measurement and polarization imaging system until the image acquisition system acquires a clear image.

[0021] Based on the image acquisition system, obtaining a plurality of transmitted light images of the Faraday sheet to be measured during the process of the magnetic field intensity of the magnetic field generated by the optical research platform increasing from 0 to saturation; wherein, when obtaining the transmitted light images, the detection signal reaches the current maximum value.

[0022] Based on all the transmitted light images, determining the measurement result of the Faraday sheet to be measured.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The Faraday sheet performance measurement and polarization imaging system of the present invention can provide high-precision Faraday rotation effect testing for the Faraday sheet to be measured by adopting a light source system, an optical research platform, a polarizer, a first analyzer, a microscopic imaging system, and an image acquisition system, accurately capture the change in the rotation angle of the Faraday sheet to be measured, and facilitate the accurate evaluation of the optical properties such as the isolation degree and insertion loss of the Faraday sheet to be measured. And by precisely controlling the laser polarization state and accurately detecting the change in the polarization direction, combined with the magnification and focusing functions of the microscopic imaging system, the magneto-optical effect of the Faraday sheet to be measured with a relatively small size can be clearly demonstrated, and the Faraday rotation angle and internal defects of the Faraday sheet to be measured can be accurately obtained and evaluated, thereby improving the accuracy, reliability, and comprehensiveness of the measurement results. At the same time, the structure design of the Faraday sheet performance measurement and polarization imaging system is simple and highly integrated, suitable for high-precision magneto-optical effect analysis and performance evaluation of the Faraday sheet to be measured, without the need to rely on additional equipment (such as transmission electron microscopes, scanning electron microscopes, etc.), and has the characteristics of high test efficiency and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 FIG. is a schematic structural diagram of the Faraday sheet performance measurement and polarization imaging system in an embodiment of the present invention when used for performance testing of the Faraday sheet to be measured;

[0025] Figure 2 FIG. is a schematic structural diagram of the optical research platform in an embodiment of the present invention;

[0026] Figure 3 FIG. is a partial structural diagram of the fixing mechanism of the optical research platform in an embodiment of the present invention;

[0027] Figure 4 FIG. is a partial structural diagram of the fixing mechanism of the optical research platform in an embodiment of the present invention.

[0028] DESCRIPTION OF THE REFERENCE NUMERALS:

[0029] 1. Light source system; 11. Laser generating mechanism; 12. Tunable filter; 2. Optical research platform; 21. Housing; 21a. Side window; 22. Magnet; 23. Sample stage; 24. Temperature control mechanism; 25. Fixing mechanism; 251. Mounting part; 25a. First mounting groove; 25c. Through hole; 252. Fixing part; 25b. Second mounting groove; 31. Polarizer; 32. First analyzer; 33. Second analyzer; 4. Microscopic imaging system; 41. Eyepiece; 42. Objective lens; 43. Compensator; 5. Image acquisition system; 51. Image acquisition mechanism; 52. First photodetector; 53. Second photodetector; 61. First beam splitter; 62. Second beam splitter; 7. Calculation and imaging system; 8. Lock-in amplifier; 9. Faraday sheet to be measured. DETAILED DESCRIPTION OF THE INVENTION

[0030] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of specific embodiments of the present invention with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments described herein. Instead, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0031] As used herein, the term "comprising" and its variations are open-ended, that is, "including but not limited to"; the term "based on" is "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiment". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc. mentioned in the present invention are only used to distinguish different devices, modules, or units, and are not used to limit the order or interdependence relationship of the functions performed by these devices, modules, or units.

[0032] It should be noted that the modifications of "one" and "a plurality" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly stated in the context, it should be understood as "one or more". The "connection" mentioned in the present invention, unless otherwise specifically stated, can refer to direct connection, or can refer to indirect connection through one or more intermediate components; it can also refer to detachable connection, can also refer to welding, or can refer to integral connection.

[0033] In combination with Figure 1 As shown, an embodiment of the present invention provides a Faraday sheet performance measurement and polarization imaging system, including a light source system 1, an optical research platform 2, a polarizer 31, a first analyzer 32, a microscopic imaging system 4, and an image acquisition system 5; the light source system 1 is used to emit laser light; the optical research platform 2 is used to set the Faraday sheet 9 to be measured and to generate a magnetic field; the microscopic imaging system 4 includes an eyepiece 41 and an objective lens 42, and the image acquisition system 5 includes an image acquisition mechanism 51; in the first propagation direction of the laser light, the light source system 1, the polarizer 31, the Faraday sheet 9 to be measured, the objective lens 42, the first analyzer 32, the eyepiece 41, and the image acquisition mechanism 51 are arranged in sequence.

[0034] In this embodiment, the Faraday slice performance measurement and polarization imaging system can be used to perform high-precision tests on the magneto-optical effect of the Faraday slice to be measured (denoted as the Faraday slice 9 to be measured, such as a Faraday slice using a magneto-optical thin film), accurately capture the optical rotation effect of the Faraday slice 9 to be measured, and provide a comprehensive evaluation of its optical performance such as isolation and insertion loss.

[0035] In the first propagation direction of the laser (taking the propagation direction of the laser emitted by the light source system 1 as the first propagation direction), the light source system 1, the polarizer 31, the Faraday slice 9 to be measured, the objective lens 42, the first analyzer 32, the eyepiece 41, and the image acquisition mechanism 51 are arranged in sequence. Specifically, the light source system 1 of the Faraday slice performance measurement and polarization imaging system is used to emit a laser, providing a high-power and stable laser output for the measurement (or test) of the Faraday slice 9 to be measured. The optical research platform 2 is used to set (fix) and support the Faraday slice 9 to be measured, ensuring the stability of the position of the Faraday slice 9 to be measured during the test, and providing a corresponding stable magnetic field environment for the Faraday slice 9 to be measured, providing stable experimental conditions for accurately measuring the Faraday rotation effect of the Faraday slice 9 to be measured. The polarizer 31 is located between the light source system 1 and the Faraday slice 9 to be measured (or the optical research platform 2), and is used to modulate the polarization state of the laser beam emitted by the light source system 1, ensuring that the laser beam output after passing through the polarizer 31 has a specific polarization direction (linearly polarized light) to adapt to the response characteristics of the Faraday slice 9 to be measured to polarized light, thereby maximizing the measurement accuracy of the Faraday rotation effect. The first analyzer 32 is located on the side of the Faraday slice 9 to be measured facing away from the polarizer 31, and is used to detect the laser with a changed polarization direction after passing through the Faraday slice 9 to be measured. For example, since the rotation angle of the first analyzer 32 has a certain relationship with the output light intensity, the maximum signal can be found by adjusting the angle of the first analyzer 32, and then the rotation angle can be calculated to achieve the accurate measurement of the change in the polarization angle of the laser, thereby obtaining the rotation angle of the Faraday slice 9 to be measured. The microscopic imaging system 4 includes an eyepiece 41 and an objective lens 42. The objective lens 42 is located between the Faraday slice 9 to be measured and the first analyzer 32, and is used to magnify (expand the beam) the laser passing through the Faraday slice 9 to be measured, ensuring that the details of the polarized light after passing through the Faraday slice 9 to be measured are clearly visible, so as to facilitate more accurately detecting the direction change of the polarized light after passing through the Faraday slice 9 to be measured in cooperation with the first analyzer 32, and at the same time ensuring that the laser spot is uniform, avoiding any non-uniformity or spot diffusion from interfering with the measurement results; the eyepiece 41 is located between the first analyzer 32 and the image acquisition mechanism 51. After the laser passing through the first analyzer 32 is focused by the eyepiece 41, the laser image is clearly presented at the receiving end of the image acquisition mechanism 51 through the imaging effect of the eyepiece 41. That is to say, the eyepiece 41 is used to focus the laser passing through the first analyzer 32, ensuring the clarity and accuracy of the laser image collected by the image acquisition mechanism 51, effectively assisting the analysis of the Faraday rotation effect, ensuring high-precision measurement results, and improving the accuracy and comprehensiveness of the performance test of the Faraday slice 9 to be measured. Among them, based on the laser image collected by the image acquisition mechanism 51, the Faraday deflection angle can be determined, and by analyzing the change in the laser light intensity, the defects of the sample of the Faraday slice 9 to be measured can be further evaluated.

[0036] In summary, the Faraday film performance measurement and polarization imaging system of this embodiment can provide high-precision Faraday rotation effect tests for the Faraday film 9 to be measured by adopting the light source system 1, the optical research platform 2, the polarizer 31, the first analyzer 32, the microscopic imaging system 4, and the image acquisition system 5, accurately capture the change in the rotation angle of the Faraday film 9 to be measured, and facilitate the accurate evaluation of the optical properties such as the isolation degree and insertion loss of the Faraday film 9 to be measured. And by precisely controlling the laser polarization state and accurately detecting the change in the polarization direction, combined with the magnification and focusing functions of the microscopic imaging system 4, the magneto-optical effect of the Faraday film 9 with a smaller size can be clearly displayed, and the Faraday rotation angle and internal defects of the Faraday film 9 to be measured can be accurately obtained and evaluated, thereby improving the accuracy, reliability, and comprehensiveness of the measurement results. At the same time, the structure of the Faraday film performance measurement and polarization imaging system is simple and has a high integration degree, which is suitable for high-precision magneto-optical effect analysis and performance evaluation of the Faraday film 9 to be measured. Without the need to rely on additional equipment (such as transmission electron microscopes, scanning electron microscopes, etc.), it has the characteristics of high test efficiency and low cost.

[0037] Optionally, as shown in Figure 1 the Faraday film performance measurement and polarization imaging system further includes a first beam splitter 61 and a second beam splitter 62, and the image acquisition system 5 further includes a first photodetector 52 and a second photodetector 53. The first beam splitter 61 is disposed between the polarizer 31 and the Faraday film 9 to be measured, and the second beam splitter 62 is disposed between the objective lens 42 and the first analyzer 32. The laser emitted by the light source system 1 and propagating along the first propagation direction is split by the first beam splitter 61 into a first laser that continues to propagate along the first propagation direction and a second laser that propagates toward the first photodetector 52. The first laser is split by the second beam splitter 62 into a third laser that continues to propagate along the first propagation direction and a fourth laser that propagates toward the second photodetector 53.

[0038] In this embodiment, the Faraday film performance measurement and polarization imaging system further includes a first beam splitter 61 and a second beam splitter 62, and the image acquisition system 5 further includes a first photodetector 52 and a second photodetector 53. The first beam splitter 61 is correspondingly disposed with the first photodetector 52, and the second beam splitter 62 is correspondingly disposed with the second photodetector 53.

[0039] After the laser emitted by the light source system 1 is adjusted to a specific polarization state by the polarizer 31, it enters the first beam splitter 61 and is split into two parts by the first beam splitter 61 (such as two linearly polarized light beams with different propagation directions). One beam that continues to propagate along the first propagation direction is denoted as the first laser, and the other beam is denoted as the second laser. The second laser propagates towards the first photodetector 52, enters the first photodetector 52 and is converted into an electrical signal for further processing and analysis. The first laser passes through the Faraday sheet 9 to be measured in the optical research platform 2, undergoes elliptical polarization, and its polarization plane rotates. Then it is expanded by the objective lens 42. The expanded light is split into two parts by the second beam splitter 62 located between the objective lens 42 and the first analyzer 32 (such as two linearly polarized light beams with different propagation directions). Among them, one beam that continues to propagate along the first propagation direction is denoted as the third laser, and the other beam is denoted as the fourth laser. The fourth laser propagates towards the second photodetector 53, enters the second photodetector 53 and is converted into an electrical signal for further processing and analysis; the third laser then passes through the first analyzer 32 and the eyepiece 41 in sequence, and after being focused by the eyepiece 41, it is clearly presented at the receiving end of the image acquisition mechanism 51.

[0040] Thus, based on the first beam splitter 61 and the second beam splitter 62, the laser before passing through the Faraday sheet is monitored by the first photodetector 52, and the laser after passing through the Faraday sheet is monitored by the second photodetector 53, so as to achieve precise tracking and quantitative analysis of the change in the polarization state of the laser, accurately capture the change in the polarization angle of the laser, and through precise signal processing and analysis, obtain the optical rotation effect data of the Faraday sheet to be measured, providing high-precision support for further evaluating the performance of the Faraday sheet (such as isolation, insertion loss, etc.).

[0041] Exemplarily, the first beam splitter 61 and the second beam splitter 62 can be selected as beam splitters for splitting the incident linearly polarized light into two linearly polarized light beams with the same intensity and orthogonal propagation directions to ensure the accuracy of the test results.

[0042] Optionally, the microscopic imaging system 4 further includes a compensator 43. The compensator 43 is arranged between the second beam splitter 62 and the first analyzer 32 and is used to adjust the light balance and compensate for chromatic aberration to make the final image clearer.

[0043] Exemplarily, the microscopic imaging system 4 further includes a lens barrel, which is placed along the first propagation direction. At least the objective lens 42, the second beam splitter 62, the compensator 43, the first analyzer 32, and the eyepiece 41 are arranged in the lens barrel. The lens barrel plays a role in protecting and positioning these components (i.e., the lens barrel serves as a carrier for these components and plays a role in fixing their positions). The microscopic imaging system 4 further includes a coarse focusing screw and a fine focusing screw, and both the coarse focusing screw and the fine focusing screw can achieve focusing by adjusting the position of the objective lens 42. In some embodiments, the magnification of the microscope can be 1000X to achieve a micron-level observation scale.

[0044] Optionally, the main axis of the first analyzer 32 is always parallel to the main axis of the polarizer 31 to ensure the accuracy of reflecting the Faraday rotation angle and sample defects based on the transmitted light intensity.

[0045] Optionally, the polarizer 31 and the first beam splitter 61 can be integrally arranged as a polarizing beam splitter to reduce space occupation.

[0046] Optionally, both the polarizer 31 and the first analyzer 32 can use polarization prisms.

[0047] Optionally, the image acquisition mechanism 51 can use a CCD camera (a digital camera with a charge-coupled device image sensor) to achieve high-resolution image acquisition and ensure accurate recording of the transmitted light image of the Faraday sheet to be measured.

[0048] Optionally, as shown in Figure 1 the Faraday sheet performance measurement and polarization imaging system further includes a computing and imaging system 7, and the computing and imaging system 7 is communicatively connected to the image acquisition mechanism 51, the first photodetector 52, and the second photodetector 53 respectively.

[0049] In this embodiment, the computing and imaging system 7 (such as a computer) is respectively communicatively connected to the image acquisition mechanism 51, the first photodetector 52, and the second photodetector 53, and is used to perform real-time processing and analysis on the data from the image acquisition mechanism 51, the first photodetector 52, and the second photodetector 53, so as to obtain the performance test results of the Faraday sheet 9 to be measured. Exemplarily, the computing and imaging system 7 receives the laser image data from the image acquisition mechanism 51, processes the electrical signals collected by the first photodetector 52 and the second photodetector 53, and based on the signal differences between the first photodetector 52 and the second photodetector 53, the computing and imaging system 7 can deduce the change in the polarization angle of the laser, and then calculate the optical rotation angle of the Faraday sheet 9 to be measured, and the calculation of the optical rotation angle can reflect the intensity and direction of the Faraday effect. Moreover, the computing and imaging system 7 can also perform image processing and result display, such as processing the laser image obtained by the image acquisition mechanism 51, extracting the characteristic information related to the Faraday optical rotation effect, and generating a detailed result report; during the processing, the image can be magnified, sharpened, and combined with the data from the photodetector to generate a comprehensive measurement result image. In some embodiments, the computing and imaging system 7 integrates all measurement data and performs advanced analysis, outputs information such as the optical rotation angle change curve and the light intensity distribution image of the Faraday sheet 9 to be measured, and generates and displays an intuitive result report, providing a comprehensive, accurate, intuitive, and clear basis for the quality evaluation of the Faraday sheet 9 to be measured, and effectively helping the user to accurately understand its performance.

[0050] Optionally, the image acquisition mechanism 51 may employ a CCD camera, and the CCD camera can transmit (upload) the image signal to the computing and imaging system 7 through a USB interface and a USB communication line; in the computing and imaging system 7, the pictures collected by the CCD camera can be viewed through corresponding software.

[0051] Optionally, as shown in Figure 1 the Faraday sheet performance measurement and polarization imaging system further includes a lock-in amplifier 8, and both the first photodetector 52 and the second photodetector 53 are communicatively connected to the computing and imaging system 7 through the lock-in amplifier 8; and the lock-in amplifier 8 is communicatively connected to the light source system 1.

[0052] In this embodiment, the lock-in amplifier 8 communicatively connected to the light source system 1, the first photodetector 52, the second photodetector 53, and the computing and imaging system 7 is used to improve the measurement accuracy and sensitivity of the Faraday sheet performance measurement and polarization imaging system in a complex signal environment.

[0053] Exemplarily, the lock-in amplifier 8 outputs a modulation signal (including modulation frequency) for laser generation and output to the light source system 1, compares the electrical signals received by the first photodetector 52 and the second photodetector 53 with a known reference signal (such as the above modulation signal), suppresses external noise or irrelevant signals (filtering process), and extracts the effective signal components (denoted as the demodulation signal). The demodulation signal obtained after processing is transmitted by the lock-in amplifier 8 to the calculation and imaging system 7, and the calculation and imaging system 7 performs further data processing, analysis, and display based on the high-precision demodulation signal provided by the lock-in amplifier 8.

[0054] Optionally, the demodulation signal obtained by the lock-in amplifier 8 can be uploaded to the calculation and imaging system 7 in digital form through a GPIB interface (a standard interface for instrument control and data transmission). The components of the demodulation signal include the signal collected by the first photodetector 52 that does not enter the Faraday sheet 9 to be measured (denoted as the reference signal), and the signal collected by the second photodetector 53 that passes through the Faraday sheet 9 to be measured (denoted as the detection signal). Exemplarily, based on the uploaded demodulation signal, the calculation and imaging system 7 saves and analyzes it, such as plotting the function of the electrical signal and time through corresponding software, increasing the signal-to-noise ratio to 60 dB. The corresponding function image is nearly a smooth straight line. When the main axis of the second analyzer rotates by a small angle, the data changes significantly, enabling more accurate positioning of the Faraday rotation angle, reducing the influence of light source instability and dark noise on the detection data, and achieving a test accuracy at the percentile level.

[0055] Optionally, as shown in Figure 1 the light source system 1 includes a laser generation mechanism 11 and a tunable filter 12; in the first propagation direction, the laser generation mechanism 11, the tunable filter 12, and the polarizer 31 are arranged in sequence.

[0056] In this embodiment, the laser generation mechanism 11 is used to generate laser and emit the laser to subsequent optical components; the laser generation mechanism 11 can be any suitable laser, such as a semiconductor laser, a fiber laser, or other types of light sources, and its main function is to provide a stable laser output. The tunable filter 12 is located between the laser generation mechanism 11 and the polarizer 31 and is used to adjust the wavelength or frequency of the laser, allowing selection of a laser beam with a specific wavelength or frequency range for output. Exemplarily, the tunable filter 12 is used to filter the laser emitted by the laser generation mechanism 11 and output it as a single-mode laser with better directivity, spatial stability, and signal quality, so as to avoid interference or noise introduced by multi-mode lasers. In this way, the light source system 1 can provide an optimized (with appropriate wavelength and frequency characteristics) laser output, provide an accurate laser source for subsequent optical detection and analysis, and ensure the reliability and accuracy of measurement results.

[0057] Optionally, the laser generating mechanism 11 can output lasers with different wavelengths or frequencies, and the wavelength or frequency of the laser can be further adjusted by the tunable filter 12. By adjusting the laser parameters output by the light source system 1, the effects of different wavelengths or frequencies on the performance of the Faraday sheet 9 to be measured can be tested, thereby further improving the comprehensiveness of the performance test of the Faraday sheet 9 to be measured.

[0058] Exemplarily, the laser generating mechanism 11 can adopt a supercontinuum white light laser, which outputs high-brightness collimated white laser with a wavelength range of 400nm - 2400nm. The laser is filtered by the tunable filter 12 and output as a single-mode laser.

[0059] Optionally, as shown in Figure 1 the Faraday sheet performance measurement and polarization imaging system further includes a second analyzer 33 disposed between the second beam splitter 62 and the second photodetector 53, and a rotating table for rotating the second analyzer 33; the fourth laser propagates from the second analyzer 33 to the second photodetector 53.

[0060] In this embodiment, the second analyzer 33 is connected to the rotating table. The rotating table is used to precisely adjust the rotation angle of the second analyzer 33, so that the second analyzer 33 can be used to accurately measure the change in the polarization angle of the laser, thereby obtaining the optical rotation angle of the Faraday sheet 9 to be measured. For example, the setting of the rotating table enables the second analyzer 33 to rotate accordingly as needed (such as enabling the angle of the first analyzer 32 to accurately match the polarization direction of the laser), so as to detect the polarization state of the fourth laser at different angles, thereby obtaining the change in the rotation angle brought about by the Faraday effect, that is, accurately acquiring the polarization information of the fourth laser.

[0061] Exemplarily, the second analyzer 33 and the rotating table for rotating the second analyzer 33 can be integrated with the lens barrel of the microscopic imaging system 4 to further improve the integration degree of the Faraday sheet performance measurement and polarization imaging system. In some embodiments, the rotating table is used to drive the second analyzer 33 to rotate around its own main axis; the minimum step size of the rotating table can be 0.00125°.

[0062] Optionally, the Faraday sheet performance measurement and polarization imaging system further includes a rotating table for rotating the first analyzer 32, so as to realize precise adjustment of the rotation angle of the first analyzer 32, and thereby realize precise polarization measurement of the laser passing through the Faraday sheet based on the image acquisition mechanism 51.

[0063] Optionally, as shown in Figure 1 and Figure 2As shown, the optical research platform 2 includes a housing 21, a magnet 22, and a sample stage 23. A sample cavity is provided inside the housing 21, and the magnet 22 and the sample stage 23 are arranged in the sample cavity. Two oppositely arranged side windows 21a are provided on the side wall of the housing 21 and penetrate the side wall, and the setting position of the side window 21a on the side wall corresponds to the sample stage 23. The sample stage 23 is used to set the Faraday sheet 9 to be measured, and the setting position of the magnet 22 in the sample cavity corresponds to the sample stage 23.

[0064] In this embodiment, the housing 21 of the optical research platform 2 has a cavity structure (this cavity structure is denoted as the sample cavity). Two side windows 21a penetrating the side wall of the housing 21 are provided on the housing 21, and the two side windows 21a are oppositely arranged so that the laser can pass through the housing 21 smoothly through the two side windows 21a. The sample stage 23 of the optical research platform 2 is arranged in the sample cavity of the housing 21 and is used to set the Faraday sheet 9 to be measured. The setting position of the side window 21a on the side wall corresponds to the sample stage 23, ensuring that the Faraday sheet 9 to be measured set on the sample stage 23 can be located on the path of the laser beam, that is, ensuring that the laser passing through the housing 21 through the two side windows 21a can pass through the Faraday sheet 9 to be measured smoothly in the sample cavity, thereby ensuring an effective test on the Faraday sheet 9 to be measured. The magnet 22 is also arranged in the sample cavity, and its setting position in the sample cavity corresponds to the sample stage 23. That is to say, the setting position of the magnet 22 corresponds to the placement position of the Faraday sheet 9 to be measured to ensure that the Faraday sheet can be affected by a stable magnetic field during the measurement process. In addition, the setting of the housing 21 can protect devices such as the magnet 22, the sample stage 23, and the Faraday sheet 9 to be measured arranged in its sample cavity, and provide a stable test environment for the Faraday sheet 9 to be measured. In some embodiments, the Faraday sheet 9 to be measured is arranged at the central position of the magnetic field generated by the magnet 22 to ensure that the Faraday sheet 9 to be measured is in a stable region of the magnetic field, reduce the uncertainty brought by the magnetic field gradient, and thus obtain a more accurate measurement result.

[0065] Optionally, the housing 21 is a structure that can be opened and closed to open the sample cavity and replace the Faraday sheet 9 to be measured.

[0066] Optionally, in combination Figure 2 As shown, the optical research platform 2 further includes a temperature control mechanism 24 arranged in the sample cavity.

[0067] In this embodiment, the temperature control mechanism 24 is arranged in the sample chamber and is used to accurately control the temperature in the sample chamber during the test, that is, to regulate the temperature of the environment where the Faraday sheet 9 to be measured is located, obtain the required test temperature, and ensure the stability of the test temperature. By setting the temperature control mechanism 24, on the one hand, it can be used to stabilize the temperature of the environment where the Faraday sheet 9 to be measured is located at a specific value or a specific range, ensuring the stability of the test environment; on the other hand, it can be used to test the influence of different temperatures on the performance of the Faraday sheet 9 to be measured, further improving the comprehensiveness of the performance test of the Faraday sheet 9 to be measured.

[0068] Exemplarily, the magnet 22 adopts a double-cone split magnet, which can provide a strong magnetic field of up to ±7T at the center of the magnetic field; and the precise temperature control within the range of 1.7K - 400K is achieved through the temperature control mechanism 24.

[0069] Optionally, the magnetic field intensity inside the optical research platform 2 can be adjusted, such as by changing the relative position between the magnet 22 and the Faraday sheet 9 to be measured, or by using an electromagnet for the magnet 22, etc., so as to accurately adjust the magnetic field intensity for the Faraday sheet 9 to be measured according to requirements.

[0070] Optionally, in combination with Figure 2 、 Figure 3 As shown, the optical research platform 2 further includes a fixing mechanism 25 detachably connected to the sample stage 23. The fixing mechanism 25 is provided with a first mounting groove 25a for accommodating the Faraday sheet 9 to be measured, and a through hole 25c penetrating the fixing mechanism 25 is provided at the bottom of the first mounting groove 25a.

[0071] In this embodiment, the optical research platform 2 further includes a fixing mechanism 25 detachably connected to the sample stage 23. This fixing mechanism 25 is used to stabilize the Faraday sheet 9 to be measured to ensure its stable position, optical path alignment during the experiment, and reduce the influence of environmental interference on the measurement accuracy. The fixing mechanism 25 is provided with a first mounting groove 25a for accommodating the Faraday sheet 9 to be measured. The size and shape of the first mounting groove 25a can be optimized according to the specifications of the sample to be measured to ensure that the Faraday sheet can be stably placed and avoid affecting the experimental results due to loosening or tilting. Among them, a through hole 25c penetrating the fixing mechanism 25 is provided at the bottom of the first mounting groove 25a for the laser to pass through to ensure the smooth progress of the measurement process.

[0072] In order to improve the adaptability and versatility of the fixing mechanism 25, the fixing mechanism 25 and the sample stage 23 adopt a detachable design, such as using threaded connection, snap connection or plug connection, etc., enabling users to replace the suitable fixing mechanism 25 according to different sizes or types of Faraday sheets, improving the experimental efficiency.

[0073] Optionally, in combination with Figure 3 、 Figure 4As shown, the fixing mechanism 25 includes a mounting portion 251 and a fixing portion 252 that are detachably connected. Figure 3 FIGS. Figure 3 to Figure 3 are schematic structural views of the mounting portion 251 from three different perspectives. Among them, Figure 3 (a) is a front view of the mounting portion 251, Figure 3 (b) is a side view (perspective view) of the mounting portion 251, Figure 3 (c) is a rear view of the mounting portion 251; Figure 4 FIGS. Figure 4 and Figure 4 are schematic structural views of the fixing portion 252 from two different perspectives. Among them, Figure 4 (a) is a front view (perspective view) of the fixing portion 252, Figure 4 (b) is a top view of the fixing portion 252. The first mounting groove 25a and the through hole 25c are provided on the mounting portion 251. The first mounting groove 25a is used to mount (accommodate) the Faraday sheet 9 to be measured, and the through hole 25c is provided through the mounting portion 251 at the bottom of the first mounting groove 25a; the fixing mechanism 25 is detachably connected to the sample stage 23 through the fixing portion 252, and the fixing portion 252 serves as the base of the mounting portion 251, providing support and limiting functions during connection to ensure the stability when the mounting portion 251 is connected to the fixing portion 252.

[0074] Exemplarily, as shown in conjunction with FIGS. Figure 3 , the mounting portion 251 is provided with a through-hole structure. The through-hole structure includes two cavities with different cross-sectional areas. The cavity with a larger cross-sectional area corresponds to the first mounting groove 25a and is used to mount (accommodate) the Faraday sheet 9 to be measured; the cavity with a smaller cross-sectional area corresponds to the through hole 25c and is used for the laser to pass through; and the groove side wall of the first mounting groove 25a serves as the slideway for mounting the Faraday sheet 9 to be measured, and the bottom end of the slideway (i.e., the bottom wall of the first mounting groove 25a) forms an inner ring shoulder to support the Faraday sheet 9 to be measured. When mounting the Faraday sheet 9 to be measured, clamping tools such as tweezers can be used to directly place the Faraday sheet 9 to be measured on the inner ring shoulder. Figure 3

[0075] Exemplarily, the fixing portion 252 is provided with mounting holes for setting fasteners (such as screws). The fixing portion 252 and the sample stage 23 are detachably connected through fasteners at the mounting holes to ensure the convenience of installation and disassembly between the fixing portion 252 and the sample stage 23, and to ensure the stability when the fixing portion 252 is connected to the sample stage 23. The fixing portion 252 is provided with a second mounting groove 25b adapted to the mounting portion 251, and the mounting portion 251 is inserted and matched with the fixing portion 252 at the second mounting groove 25b to improve the convenience of replacing the mounting portion 251 on the fixing portion 252, that is, to improve the convenience of replacing the Faraday sheet 9 to be measured and to improve the efficiency of the Faraday sheet performance measurement and the polarization imaging system for performance testing of multiple Faraday sheets 9 to be measured.

[0076] Figure 1 As shown in conjunction with Figure 1As shown in the figure, another embodiment of the present invention provides a method for measuring the performance of a Faraday sheet and polarization imaging, based on the above-mentioned Faraday sheet performance measurement and polarization imaging system, including:

[0077] Control the light source system 1 of the Faraday sheet performance measurement and polarization imaging system to emit laser light with a first preset parameter, and finely adjust the optical path so that the reference signal and the detection signal meet the preset conditions; wherein, the reference signal is the signal obtained by the first photodetector 52 of the image acquisition system 5 of the Faraday sheet performance measurement and polarization imaging system, and the detection signal is the signal obtained by the second photodetector 53 of the image acquisition system 5.

[0078] Install the Faraday sheet 9 to be measured on the optical research platform 2 of the Faraday sheet performance measurement and polarization imaging system.

[0079] Focus the objective lens 42 of the microscopic imaging system 4 of the Faraday sheet performance measurement and polarization imaging system until the image acquisition system 5 acquires a clear image.

[0080] Based on the image acquisition system 5, obtain multiple transmitted light images of the Faraday sheet 9 to be measured during the process of the magnetic field intensity of the magnetic field generated by the optical research platform 2 increasing from 0 to saturation; wherein, when acquiring the transmitted light images, the detection signal reaches the current maximum value.

[0081] Based on all the transmitted light images, determine the measurement result of the Faraday sheet 9 to be measured.

[0082] The method of this embodiment is used for a Faraday slice performance measurement and polarization imaging system to implement the performance test of the Faraday slice 9 to be measured. Specifically, first, control the light source system 1 of the Faraday slice performance measurement and polarization imaging system to emit laser according to the required first preset parameters, and finely adjust the optical path, that is, finely adjust the emission direction of the laser or the positions of the components of the Faraday slice performance measurement and polarization imaging system, to ensure that the propagation path of the laser beam is accurately aligned with the optical elements of the Faraday slice performance measurement and polarization imaging system, and ensure that the reference signal obtained by the first photodetector 52 and the detection signal obtained by the second photodetector 53 meet the preset conditions, so as to reduce the measurement error and improve the measurement accuracy; wherein, the preset conditions include that the ratio of the reference signal to the detection signal is close to or equal to 2×Tp, and Tp is the main axis transmittance of the polarization prism used by the second analyzer 33. Next, install the Faraday slice 9 to be measured on the optical research platform 2 of the Faraday slice performance measurement and polarization imaging system, and ensure that the Faraday slice 9 to be measured is located in the effective area of the optical path so that the laser can transmit through. Subsequently, adjust the focal length of the objective lens 42 of the microscopic imaging system 4 until the image acquisition system 5 obtains a clear transmitted light image, ensuring that the change of the transmitted light can be accurately recorded during the subsequent measurement process. Then, gradually adjust the magnetic field intensity of the optical research platform 2, increasing it from 0 Oe to the saturation state (that is, the magnetization state inside the Faraday slice 9 to be measured reaches saturation and no longer changes with the increase of the magnetic field), and in this process, use the image acquisition system 5 to obtain multiple transmitted light images of the Faraday slice 9 to be measured, such as image acquisition when the magnetic field intensity increases by a certain value; and each time a transmitted light image is acquired, by adjusting the angle of the second analyzer 33, make the detection signal received by the second photodetector 53 reach the current maximum value to ensure the accuracy of the measurement data. Finally, based on all the acquired transmitted light images, analyze the optical response characteristics of the Faraday slice 9 to be measured at different magnetic field intensities, calculate the change of the Faraday rotation angle, and further calculate the key parameters of the Faraday effect, such as the Verdet constant, etc., so as to obtain the performance index of the Faraday slice 9 to be measured. In this way, the measurement accuracy can be effectively improved, and efficient and reliable test data support can be provided.

[0083] For the Faraday slice performance measurement and polarization imaging method, exemplarily, first, turn on the light source system 1, such as turning on the laser generating mechanism 11, set the tunable filter 12, and output a single-mode collimated laser with the required wavelength through the light source system 1 based on the first preset parameters; rotate the second analyzer to make its main axis parallel to the main axis of the polarizer, and turn on the measurement software for the photodetector on the calculation and imaging system 7, and finely adjust the optical path to make the ratio of the reference signal to the detection signal close to 2×T p , T pis the main axis transmittance of the polarizer polarizing prism. Thereafter, open the sample chamber of the optical research platform 2, install the Faraday sheet 9 to be measured, and close the sample chamber after installation. Then, open the corresponding software for the microscopic imaging system 4 on the calculation and imaging system 7, move the microscope barrel close to the observation window, and focus the objective lens 42 until the software display screen is clear, and at this time, set the photo collected when the magnetic field is 0 Oe as the background for subsequent comparison and analysis. Then, apply an external magnetic field to saturation, observe and record the brightness change of the image displayed on the corresponding software of the microscopic imaging system 4, and save the picture in the calculation and imaging system 7; among them, based on the measurement software for the photodetector, when the detection signal intensity decreases, rotate the second polarizer 33 until the detection signal reaches the maximum value again, and collect the image, and record the current rotation angle as the Faraday rotation angle of the Faraday sheet 9 to be measured under the current magnetic field intensity. Then, if it is necessary to change the laser wavelength and environmental temperature, the tunable filter 12 and the temperature control mechanism 24 can be set accordingly, and the above-mentioned Faraday rotation angle measurement steps can be repeated. After the measurement is completed, turn off the laser generating mechanism 11, the tunable filter 12, the optical research platform 5, etc. in sequence to end the current experiment.

[0084] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A Faraday plate performance measurement and polarization imaging system, characterized in that: The invention comprises a light source system (1), an optical research platform (2), a polarizer (31), a first analyzer (32), a microscopic imaging system (4) and an image acquisition system (5); the light source system (1) is used for emitting laser light; the optical research platform (2) is used for setting a Faraday plate (9) to be measured and for generating a magnetic field; the microscopic imaging system (4) comprises an eyepiece (41) and an objective lens (42); and the image acquisition system (5) comprises an image acquisition mechanism (51); in a first propagation direction of the laser light, the light source system (1), the polarizer (31), the Faraday plate (9) to be measured, the objective lens (42), the first analyzer (32), the eyepiece (41) and the image acquisition mechanism (51) are arranged in sequence.

2. The Faraday plate performance measurement and polarization imaging system according to claim 1, characterized in that: The image acquisition system (5) further comprises a first beam splitter (61) and a second beam splitter (62), and the image acquisition system (5) further comprises a first photodetector (52) and a second photodetector (53), wherein the first beam splitter (61) is arranged between the polarizer (31) and the Faraday plate (9) to be measured, and the second beam splitter (62) is arranged between the objective lens (42) and the first analyzer (32); the laser light emitted by the light source system (1) and propagating along the first propagation direction is divided into a first laser light that continues to propagate along the first propagation direction and a second laser light that propagates toward the first photodetector (52) by the first beam splitter (61), and the first laser light is divided into a third laser light that continues to propagate along the first propagation direction and a fourth laser light that propagates toward the second photodetector (53) by the second beam splitter (62).

3. The Faraday plate performance measurement and polarization imaging system according to claim 2, characterized in that: It also includes a computing and imaging system (7), which is respectively connected to the image acquisition mechanism (51), the first photodetector (52) and the second photodetector (53) in communication.

4. The Faraday plate performance measurement and polarization imaging system as claimed in claim 3, characterized in that: It also includes a phase-locked amplifier (8), through which the first photodetector (52) and the second photodetector (53) are both connected to the computing and imaging system (7) for communication; and the phase-locked amplifier (8) is connected to the light source system (1) for communication.

5. The Faraday plate performance measurement and polarization imaging system according to any one of claims 1 to 4, characterized in that: The light source system (1) comprises a laser generating mechanism (11) and a tunable filter (12); in the first propagation direction, the laser generating mechanism (11), the tunable filter (12) and the polarizer (31) are arranged in sequence.

6. The Faraday plate performance measurement and polarization imaging system according to any one of claims 2 to 4, characterized in that: It also includes a second polarizer (33) arranged between the second beam splitter (62) and the second photodetector (53), and a rotating table for rotating the second polarizer (33); the fourth laser is transmitted to the second photodetector (53) through the second polarizer (33).

7. The Faraday plate performance measurement and polarization imaging system according to any one of claims 1 to 4, characterized in that: The optical research platform (2) comprises a shell (21), a magnet (22) and a sample stage (23); a sample cavity is provided in the shell (21), and the magnet (22) and the sample stage (23) are arranged in the sample cavity; two side windows (21a) arranged opposite to each other are arranged on the side wall of the shell (21) and penetrate the side wall, and the arrangement position of the side windows (21a) on the side wall corresponds to the sample stage (23); the sample stage (23) is used to arrange the Faraday plate (9) to be measured, and the arrangement position of the magnet (22) in the sample cavity corresponds to the sample stage (23).

8. The Faraday plate performance measurement and polarization imaging system according to claim 7, characterized in that: The optical research platform (2) also includes a temperature control mechanism (24) arranged in the sample chamber.

9. The Faraday plate performance measurement and polarization imaging system according to claim 7, characterized in that: The optical research platform (2) further comprises a fixing mechanism (25) detachably connected to the sample stage (23), wherein the fixing mechanism (25) is provided with a first mounting groove (25a) for accommodating the Faraday plate (9) to be measured, and a through hole (25c) penetrating the fixing mechanism (25) is provided at the bottom of the first mounting groove (25a).

10. A Faraday plate performance measurement and polarization imaging method, characterized in that: Based on the Faraday plate performance measurement and polarization imaging system according to any one of claims 1 to 9, the Faraday plate performance measurement and polarization imaging method comprises: Controlling the light source system (1) of the Faraday plate performance measurement and polarization imaging system to emit laser light with a first preset parameter, and fine-tuning the optical path so that the control signal and the detection signal meet preset conditions; wherein the control signal is a signal acquired by a first photodetector (52) of an image acquisition system (5) of the Faraday plate performance measurement and polarization imaging system, and the detection signal is a signal acquired by a second photodetector (53) of the image acquisition system (5); Installing the Faraday plate (9) to be measured onto the optical research platform (2) of the Faraday plate performance measurement and polarization imaging system; Focusing the objective lens (42) of the microscopic imaging system (4) of the Faraday plate performance measurement and polarization imaging system until the image acquisition system (5) acquires a clear image; Based on the image acquisition system (5), a plurality of transmitted light images about the Faraday plate (9) to be measured are obtained when the magnetic field intensity of the magnetic field generated by the optical research platform (2) changes from 0 to saturation; wherein when the transmitted light image is obtained, the detection signal reaches a current maximum value; Based on all the transmitted light images, a measurement result on the Faraday plate (9) to be measured is determined.

Images