A birefringence device multi-dimensional experimental device and experimental method

Abstract

The application discloses a birefringent device multi-dimensional experiment device and experiment method, which takes birefringent material in a birefringent device in the shape of a parallelepiped as an experiment object; the birefringent material produces birefringence on incident light, and emits ordinary light and extraordinary light, the directions of the two beams of emitted light are parallel, and the polarization directions are perpendicular to each other; the experiment device emits specific types of incident light aiming at the birefringent device, detects the direction, intensity and polarization direction of the ordinary light and the extraordinary light emitted by the birefringent device, and completes multi-dimensional experiments. The application is based on simultaneously tracking an optical path and monitoring the polarization state of emitted light to implement research on multiple influencing factors of the birefringent device, and is suitable for teaching demonstration and research experiments due to low cost.

Description

Technical Field

[0001] This invention belongs to the field of birefringence measurement technology, and more specifically relates to a multidimensional experimental device for birefringent devices, used to acquire the refractive index and phase difference of birefringent devices in real time. Background Technology

[0002] Birefringence has wide applications in both physics experiments and industrial testing, and the relationship between the birefringence performance of birefringent devices and external influencing factors is worthy of study. Currently, commonly used measurement methods include the refractometer method, the elliptically polarized light method, and the compensator method. The refractometer method requires visual observation of the light-dark boundary line, and it is difficult to determine the maximum and minimum values ​​of the birefringence during the rotation of the birefringent crystal, thus lacking precision. The elliptically polarized light method requires manual rotation of the analyzer and reading of the optical power meter; its efficiency in measuring a single elliptically polarized beam is low, making it unsuitable for large-scale studies. The compensator method requires a large number of thin glass slides with known refractive indices, and observing changes in the diffraction pattern is difficult. All of the above methods are not suitable for flexibly adding external influencing factors, cannot obtain the refractive index and the resulting phase difference of the birefringent device in real time during the experiment, and the measurement process is easily affected by environmental interference.

[0003] Traditional measurement methods have significant drawbacks in terms of measurement accuracy, system stability, and ease of operation. Different measurement devices are required for different research objects, which not only increases measurement costs but also leads to inconsistent results when measuring large quantities of birefringent devices. Furthermore, the manual adjustment of polarizers and incident angles during operation, coupled with the disconnect between the obtained data from multiple sets of measurements and the calculation of experimental results, makes these methods particularly unsuitable for real-time industrial testing. Summary of the Invention

[0004] This invention provides a multidimensional experimental device and method for birefringent devices to avoid the aforementioned prior art. It is based on simultaneously tracking the optical path and monitoring the polarization state of the emitted light to conduct research on multiple influencing factors of birefringent devices, and is suitable for teaching demonstrations and research experiments due to its low cost.

[0005] To achieve its objectives, the present invention employs the following technical solution: The present invention relates to a multidimensional experimental device for birefringent devices, which uses birefringent materials in birefringent devices with a parallelepiped shape as experimental objects. The birefringent materials produce birefringence of incident light and emit ordinary and extraordinary light. The two emitted light beams are parallel in direction and perpendicular to each other in polarization direction.

[0006] The multidimensional experimental device for birefringent devices of this invention is characterized by the following: the experimental device is designed to conduct multidimensional experiments by detecting the direction, intensity, and polarization direction of ordinary and extraordinary light emitted from the birefringent device after emitting a specific type of incident light, thereby obtaining experimental data on refractive index and phase difference; a planetary gear-type optical platform is provided, which has an annular guide rail and at least two sets of optical instrument support platforms slidingly fitted on the annular guide rail. A stepper motor for driving the transmission gear is provided on the optical instrument support platform. An internal gear base with an internal gear ring is provided at the bottom of the annular guide rail. The transmission gear meshes with the internal gear ring in the internal gear base, realizing the stepper motor driving the optical instrument support platform on the annular guide rail. The optical instrument carrier platform is moved, and the rotation angle of the stepper motor determines the rotation angle of the optical instrument carrier platform. A laser emitter for setting the laser is installed on one of the optical instrument carrier platforms, so that the laser beam projected by the laser beam toward the birefringent device can be adjusted to a set incident angle as the optical instrument carrier platform moves on the annular guide rail. An optical sensor for detecting the light emitted from the birefringent device is set on a lead screw in the light-tracking module and can move vertically on the lead screw to adjust the height of the optical sensor. The light-tracking module is installed on another optical instrument carrier platform, so that the optical sensor can rotate around the center of the planetary gear optical platform as the optical instrument carrier platform moves on the annular guide rail, realizing the motion trajectory of the semi-cylindrical surface of the photoelectric sensor.

[0007] The multidimensional experimental device for birefringent devices of this invention is characterized by the following: a device placement platform, a camera module, an analyzer, and a pressure applicator are fixedly mounted on the internal gear base of the planetary gear optical platform; the device placement platform is used to set up a supplementary light and place the birefringent device, and by adjusting the tilt angle of the supplementary light, the left side and front side of the birefringent device are both perpendicular to the horizontal plane, the left side of the birefringent device is the laser incident surface, and the left side of the birefringent device is located at the center of the planetary gear optical platform, and the right side of the birefringent device is the exit surface; the camera module is used to mount a camera, so that the camera is directly above the birefringent device; the analyzer is a polarization stepper motor mounted on a polarization support, which rotates through a meshing gear that drives a second polarizer; the pressure applicator is used to apply pressure to the front end face of the birefringent device.

[0008] The multidimensional experimental device for birefringent devices in this invention is also characterized by: The emitted light from the laser, after passing through the first polarizer, is incident on the left side of the birefringent device. The angle between the direction of the laser and the normal to the left side of the birefringent device is the incident angle. Controlling the stepper motor to rotate can make the laser emitter rotate around the center of the planetary gear optical platform and keep the laser emission direction facing the center of the planetary gear optical platform, thereby controlling the change of the incident angle. The birefringent device emits ordinary and unusual light parallel to the incident laser from its right side, and the ordinary and unusual light are incident toward the analyzer. The second polarizer, by adjusting the rotation position of the second polarizer, causes ordinary light and extraordinary light emitted from the right side of the birefringent device to be emitted as two parallel beams with the same polarization direction as the second polarizer after passing through the second polarizer; The photoelectric sensor moves along a semi-cylindrical trajectory to obtain detection signals of the position and intensity of two parallel beams of light, and transmits them to the host computer in the operation terminal. The camera is used to capture images of the birefringent device when pressure is applied to the front surface of the device by a pressure applicator, and the light source is emitted by the supplementary light and projected onto the birefringent device. The images are used to analyze the stress magnitude and distribution of the birefringent material in the horizontal direction within the birefringent device.

[0009] The experimental method for the multidimensional experimental apparatus for birefringent devices of the present invention is to operate the experimental apparatus according to the following procedure: Step 1: Set the analyzer's rotation speed and sampling rate, and turn on the laser; Step 2: Control the centering and rotation of the second polarizer in the analyzer, control the movement of the optical instrument support platform along the annular guide rail, and control the up and down movement of the photoelectric sensor along the lead screw, so that the photoelectric sensor finds the exit point of the laser after passing through the birefringent in the semi-cylindrical surface; when the photoelectric sensor detects that the light intensity exceeds the threshold, it is determined that the outgoing light has been captured. Based on the property that the polarization directions of ordinary and extraordinary rays are perpendicular, the o-ray and e-ray are separated by rotating the second polarizer, and the coordinates of their detection points are recorded as follows: and Then we have: o optical refractive index As shown in equation (1): (1); in: The perpendicular distance between the front and back surfaces of a birefringent crystal; The angle of refraction of the o-ray; Angle of incidence; Coordinates of the exit point of the e-ray from the back surface of the birefringent crystal As shown in equation (2): (2); e-ray effective refractive index The relationship conforms to equation (3): (3); in: The angle between the e-ray ray and the optical axis; The angle between the e-wave vector and the optical axis; The principal refractive index of the e-ray; The angle between the optical axis and the normal to the front surface of the crystal; The angle between the principal section of the crystal and the incident plane; Step 3: Control the pressure applicator to apply pressure to the birefringent device, control the second polarizer in the analyzer to rotate a certain angle at set time intervals and then stop, read the data by the photoelectric sensor, draw the polar coordinate diagram of light intensity and corresponding angle in real time, obtain the calculation results including phase difference and light intensity, and then use the neural network to back-determine the pressure value applied by the pressure applicator. Step 4: Change the voltage between the transparent conductive glass in the birefringent device, control the second polarizer in the analyzer to rotate a certain angle every set time and then stop, read the data by the photoelectric sensor, draw the polar coordinate diagram of light intensity and corresponding angle in real time, obtain the calculation results including phase difference and light intensity, and then use the neural network to back-determine the voltage value applied between the transparent conductive glass. Step 5: Turn on the fill light, observe the diffraction fringes on the upper surface of the birefringent device through the camera, calculate the stress distribution in the horizontal direction of the birefringent device based on its brightness and color, and obtain the numerical relationship through interference color chart calculation.

[0010] The experimental method of the multidimensional experimental device for birefringent devices of the present invention is characterized by the following: by replacing modules, other influencing factors are applied to the birefringent device; the second polarizer in the analyzer is controlled to rotate at a certain angle every set time and then stop; the data is read by the photoelectric sensor; the polar coordinate diagram of light intensity and corresponding angle is plotted in real time; the calculation results including phase difference and light intensity are obtained; and then the corresponding influencing factor values ​​are determined by back-reasoning through neural network.

[0011] Compared with existing technologies, the beneficial effects of this invention are reflected in: 1. This invention features a planetary gear-type optical platform, ensuring that the optical instrument support platform always faces the center of the annular guide rail. When driven by a stepper motor, the rotation angle of the stepper motor corresponds to the angle of movement of the optical platform, thus functioning as a goniometer and providing real-time feedback on the current position. The optical instrument support platform is modularly designed, allowing the required number and types of installations to be determined according to experimental needs. Its movement can be independently controlled, and its current position can be fed back in real time.

[0012] 2. In this invention, the movement of the light-tracking module on the optical instrument carrying platform, combined with the vertical movement controlled by the lead screw, enables the photoelectric sensor to maintain its orientation towards the center of the circular guide rail and obtain the detection range of the semi-cylindrical surface.

[0013] 3. This invention uses a polarizer in conjunction with a photoelectric sensor. After the polarizer rotates to a set angle, the photoelectric sensor reads the current light intensity, realizing automatic polarization of the emitted light. It also draws a polar coordinate graph of light intensity with respect to the polarization angle in real time, which intuitively reflects the polarization state of the emitted light.

[0014] 4. This invention solves the problem of difficulty in distinguishing between ordinary and extraordinary light emission points when the offset is small by rotating the analyzer at a 90° angle. When the two emission points are close together, if the spot radius is greater than the distance, it is difficult to distinguish between them. This phenomenon often occurs in devices with low birefringence. Utilizing the characteristic that the polarization directions of ordinary and extraordinary light are perpendicular, this invention rotates the analyzer to ensure that only ordinary or extraordinary light is emitted, thus preventing mutual interference and eliminating the resolution limit problem in the light-tracking process of the tracking module.

[0015] 5. In this invention, the birefringent device is positioned at a specific location, including the incident surface being at the center of the annular guide rail, to ensure that the position of the incident point remains unchanged regardless of the angle from which the incident light enters. Considering that the cleavage planes of birefringent crystals often do not form a cuboid, this invention sets the incident and exit surfaces of the birefringent device to be perpendicular to the horizontal plane, so that both the incident and exit light are horizontal. In the vertical direction, this invention ensures that the height of the laser is between the lowest point of the upper surface and the highest point of the lower surface of the birefringent device, allowing it to pass through.

[0016] 6. This invention designs a neural network algorithm to link the polarization state of the outgoing light represented by multiple sets of data with the physical characteristics of the birefringent device and the external influencing factors received. This can form a mathematical law based on the algorithm, and the situation of the external influencing factors, including the magnitude of the applied pressure and the applied electric field, can be deduced from the data results. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the overall structure of the present invention from another angle.

[0019] Figure 3 This is a schematic diagram of the operation terminal structure in this invention.

[0020] Figure 4 This is a schematic diagram of the device placement platform and pressure applicator structure in this invention.

[0021] Figure 5 This is a schematic diagram of the detector structure in this invention.

[0022] Figure 6 This is a schematic diagram of the planetary gear optical platform structure in this invention.

[0023] Figure 7 This is a schematic diagram of the overall structure of the present invention.

[0024] Figure 8 This is a schematic diagram of the birefringent device structure in this invention.

[0025] Figure 9 This is a schematic diagram of the optical sensor detection optical path in this invention.

[0026] Figure 10 This is a schematic diagram of the neural network used in this invention.

[0027] Figure 11 A table showing the color and stress produced by white light passing through an orthogonal polarizer.

[0028] The diagram is labeled as follows: 1. Operating terminal, 11. Host computer, 12. Microcontroller, 13. Touch screen, 14. Operating terminal casing, 15. Joystick, 16. Keyboard; 2. Laser emitter, 21. Support frame, 22. Laser, 23. Laser mounting cylinder, 24. First polarizer; 3. Camera module, 31. Camera, 32. Triangular mounting bracket, 33. Support beam, 34. Triangular connecting frame, 35. Support arm; 4. Device placement platform, 41. Quick-release bracket, 42. Fill light, 43. Birefringent device, 431. Birefringent material, 432. Polarizing film, 433. Transparent conductive glass; 5. Polarizer. 51 Second polarizer, 52 Gear lens clip, 53 Stepped gear, 54 Quick-release polarization checker bracket, 55 Stepper motor; 6 Tracking module, 61 Miniature stepper motor, 62 Slide base, 63 Support base, 64 Photoelectric sensor, 65 Nut, 66 Lead screw; 7 Pressure applicator, 71 Washer, 72 Spring push rod, 73 Push rod seat, 74 Slide, 75 Slide rail, 76 Pressure bracket; 8 Planetary gear optical platform, 81 Arc slider, 82 Stepper motor, 83 Optical instrument support platform, 84 Transmission gear, 85 Circular guide rail, 86 Internal gear base. Detailed Implementation

[0029] See Figure 1 and Figure 2 In this embodiment, the multidimensional experimental device for birefringent devices includes: a laser emitter 2, a camera module 3, a device placement platform 4, a polarizer 5, a beam tracking module 6, a pressure applicator 7, and a planetary gear optical platform 8.

[0030] like Figure 3 As shown, the operation terminal 1 includes a host computer 11, a microcontroller 12, a touch screen 13, an operation terminal housing 14, a joystick 15, and a keyboard 16. The joystick 15 has two dimensions and senses the direction and degree of push through the Hall effect.

[0031] like Figure 2As shown, the laser emitter 2 includes a support frame 21, a laser 22, a laser fixing cylinder 23, and a first polarizer 24. The laser fixing cylinder 23 is fixedly connected to the support frame 21, with one end clipped to fix the first polarizer 24 and the other end used for embedded mounting of the laser 22. The camera module 3 includes a camera 31, a tripod fixing frame 32, a support beam 33, a tripod connecting frame 34, and a support arm 35. The camera 31 can be adjusted to be directly above the birefringent device 43. Parallel light sequentially passes from the supplementary light 42, the lower polarizing film 432, the lower transparent conductive glass 433, the birefringent material 431, the upper transparent conductive glass 433, and the upper polarizing film 432 to the camera 31. Specifically, an ordinary camera is used, with polarizers perpendicular to the polarization direction pasted on the top and bottom of the birefringent material 431. After passing through the white light generated by the supplementary light, the change in color image can be directly observed, and this image can be correlated with the stress on the birefringent material.

[0032] like Figure 4 As shown, the device placement platform 4 includes a quick-release bracket 41, a supplementary light 42, and a birefringent device 43. To ensure that the incident and exit surfaces of the calcite are perpendicular to the horizontal plane, the upper plane of the quick-release bracket 41 is tilted at an angle of 8.96° about the horizontal direction and at an angle of 14.14° about the vertical direction. This design is also applicable to crystals with other cleavage planes.

[0033] like Figure 5 As shown, the polarizer 5 includes a second polarizer 51, a gear lens clip 52, a stepped gear 53, a quick-release polarizer bracket 54, and a stepper motor 55.

[0034] like Figure 7 As shown, the light-tracking module 6 includes a miniature stepper motor 61, a slide base 62, a support base 63, a photoelectric sensor 64, a nut 65, and a lead screw 66. The photoelectric sensor 64 and the nut 65 behind it are configured to cooperate with the lead screw 66. The rotation of the lead screw 66 drives the photoelectric sensor 64 to move up and down.

[0035] like Figure 4 As shown, the pressure applicator 7 includes a pad 71, a spring push rod 72, a push rod seat 73, a slide table 74, a slide rail 75, and a pressure bracket 76; the spring push rod 72 and the push rod seat 73 are connected by a spring, and pressure is freely applied to the birefringent device 43 by varying degrees of extension and retraction.

[0036] like Figure 6As shown, the planetary gear optical platform 8 includes an arc-shaped slider 81, a stepper motor 82, an optical instrument support platform 83, a transmission gear 84, an annular guide rail 85, and an internal gear base 86. The arc-shaped slider 81 slides around the annular guide rail 85, and the internal gear base 86 has a ring of teeth that mesh with the transmission gear 84. The central base has a square hole to insert a quick-release bracket 41 and a quick-release polarization bracket 54. The incident surface of the birefringent device 43 coincides with the center of the internal gear base 86 to ensure that the laser incident point remains unchanged. The annular guide rail 85 has holes at 0°, 30°, 60°, and 90° for easy positioning.

[0037] like Figure 8 As shown, the birefringent device 43 includes a birefringent material 431, a polarizing film 432, and a transparent conductive glass 433. The polarizing film 432 consists of two pieces with perpendicular polarization directions, one above the other. The transparent conductive glass 433 is made of indium tin oxide and also consists of two pieces, one above the other. The birefringent device 43 has a "sandwich" structure, which allows for multiple experimental measurements of a single sample to be performed simultaneously through multiple stacked layers. The birefringent material 431 can be a birefringent crystal such as calcite or an amorphous material such as glass. The transparent conductive glass is attached above and below the birefringent material, so that it can be connected to an adjustable power supply to generate a controllable uniform electric field without obstructing the observation of the birefringent material in the vertical direction by the supplementary light and the camera.

[0038] like Figure 9 As shown, in order to obtain Figure 9 The detection optical path shown requires that the laser 22, the first polarizer 24, the second polarizer 51, the birefringent device 43, and the photoelectric sensor 64 be set to the same horizontal height.

[0039] The modular structure is reflected in the following two aspects: First, the optical modules are replaceable. Laser emitters 2, tracking modules 6, or CCD cameras can be installed on the optical instrument platform 83 via screws or adhesive, enabling the emission of different beams and the measurement of different data. Second, the influencing factor application devices are replaceable. The square slot in the internal toothed base 86 can accommodate modules such as pressure applicators 7, and the transparent conductive glass 433 in the birefringent device 43, connected to an adjustable power supply, can generate an external electric field.

[0040] In practice, the corresponding technical measures also include: like Figure 6As shown, the internal gear base 86 of the planetary gear optical platform 8 has a cross-shaped fixing bracket inside its base, with a square slot on it; the internal gear base 86 is connected to the annular guide rail 85 through a socket, and has an annular slot in the middle to facilitate the passage of the drive shaft of the stepper motor 82; the transmission gear 84 is constrained between the internal gear base 86 and the annular guide rail 85, meshes with the teeth of the internal gear base 86, and is fastened to the drive shaft of the stepper motor 82 by screws; the stepper motor 82 sits on the arc-shaped slider 81, and its drive shaft passes through the hole of the arc-shaped slider 81; the arc-shaped slider 81 has baffles on both sides, which hold the annular guide rail 85 and slide on it.

[0041] like Figure 2 and Figure 7 As shown, the light tracking module 6 is mainly supported by a support base 63. The slide base 62 is fixed to the support base 63 by screws. A micro stepper motor 61 is hung on the support base 63. One end of the lead screw 66 is the stepper motor 61, and the other end is connected to the bottom end of the slide base 62. A slider with a photoelectric sensor 64 passes through the middle. The slider is a nut with internal threads. The photoelectric sensor 64 is used to convert light intensity into current signal.

[0042] like Figure 2 and Figure 6 As shown, the laser emitter 2 is also fixed to the rear side of the optical instrument support platform 83 by a slot, and the support frame 21 covers the laser fixing cylinder 23, so that the laser fixing cylinder 23 is parallel to the direction of the laser beam.

[0043] The device is controlled and data is processed using an operating terminal, and the tracking module is moved up, down, left, and right using a joystick.

[0044] External pressure and external electric field can be selected as external influencing factors for birefringent devices, or other influencing factors can be omitted or set.

[0045] Marking holes are provided at 0°, 30°, 60°, 90°, 120°, 150°, and 180° on the annular guide rail for positioning.

[0046] A scale is set on the spring push rod in the pressure applicator to identify the pressing depth and record the pressure magnitude. A thin-film pressure sensor is set at the pressing point to read and transmit signals in real time.

[0047] This embodiment uses the birefringent material 431 in a birefringent device 43 with a parallelepiped shape as the experimental object. The birefringent material 431 produces birefringence of incident light, and emits ordinary light and extraordinary light. The two emitted light beams are parallel in direction and perpendicular to each other in polarization direction. The experimental device is designed to emit a specific type of incident light to the birefringent device 43, and to detect the direction, intensity and polarization direction of the ordinary light and extraordinary light emitted by the birefringent device 43 to complete a multidimensional experiment and obtain experimental data on refractive index and phase difference.

[0048] The planetary gear optical platform 8 has an annular guide rail 85 and at least two sets of optical instrument support platforms 83 that slide on the annular guide rail 85. A stepper motor 82 is mounted on each optical instrument support platform 83 to drive a transmission gear 84. An internal gear base 86 with an internal gear ring is located at the bottom of the annular guide rail 85. The transmission gear 84 meshes with the internal gear ring in the internal gear base 86, enabling the stepper motor 82 to drive the optical instrument support platform 83 to move on the annular guide rail 85. The rotation angle of the optical instrument support platform 83 is determined by the rotation angle of the stepper motor. A laser emitter 2, used to mount a laser 22, is mounted on one of the optical instrument support platforms. On platform 83, the laser beam projected by laser 22 toward birefringent device 43 can be adjusted to a set incident angle as the optical instrument support platform 83 moves on the annular guide rail 85; the optical sensor 64 for detecting the light emitted from birefringent device 43 is mounted on lead screw 66 in the light tracking module 6, and can move vertically on lead screw 66 to adjust the height of optical sensor 64. The light tracking module 6 is mounted on another optical instrument support platform 83, so that optical sensor 64 can rotate around the center of planetary gear optical platform 8 as optical instrument support platform 83 moves on annular guide rail 85, realizing the motion trajectory of the semi-cylindrical surface of photoelectric sensor 64.

[0049] On the internal gear base 86 of the planetary gear optical platform 8, a device placement platform 4, a camera module 3, an analyzer 5, and a pressure applicator 7 are also fixedly installed. The device placement platform 4 is used to set up the fill light 42 and place the birefringent device 43. By adjusting the tilt angle of the fill light 42, the left side and front side of the birefringent device 43 are perpendicular to the horizontal plane. The left side of the birefringent device 43 is the laser incident surface, and the left side of the birefringent device 43 is located at the center of the planetary gear optical platform 8. The right side of the birefringent device 43 is the exit surface. The camera module 3 is used to install the camera 31, so that the camera 31 is directly above the birefringent device 43. The analyzer 5 is a polarization stepper motor 55 set on the polarization bracket 54. The polarization stepper motor 55 rotates through the meshing gears carrying the second polarizer 51. The pressure applicator 7 is used to apply pressure to the front end face of the birefringent device 43.

[0050] The emitted light from laser 22, after passing through the first polarizer 24, is incident on the left side of the birefringent device 43. The angle between the laser direction and the normal to the left side of the birefringent device 43 is the angle of incidence. Controlling the stepper motor 82 to rotate the laser emitter 2 around the center of the planetary gear optical platform 8, while maintaining the laser emission direction towards the center of the planetary gear optical platform 8, thereby controlling the change of the angle of incidence. The birefringent device 43 emits ordinary and extraordinary light parallel to the incident laser from its right side. The ordinary and extraordinary light are incident towards the analyzer 5. By adjusting the rotation position of the second polarizer 51, the light emitted from the birefringent device 43 is directed towards the analyzer 5. The ordinary and unusual light emitted from the right side of the device 3, after passing through the second polarizer 51, are emitted as two parallel beams with the same polarization direction as the second polarizer 51; the photoelectric sensor 64 moves along the trajectory of the semi-cylindrical surface to obtain the detection signals of the position and light intensity of the two parallel beams, and transmits them to the host computer 11 in the operation terminal 1; the camera 31 is used to capture the image when the light source is emitted by the supplementary light 42 and projected onto the birefringent device 43 when pressure is applied to the front end of the birefringent device 43 by the pressure applicator 7, and is used to analyze the stress magnitude and distribution of the birefringent material 431 in the horizontal direction in the birefringent device 43.

[0051] In this embodiment, the experimental method of the multidimensional experimental device for birefringent devices is operated according to the following procedure: Step 1: Set the rotation speed and sampling rate of the analyzer 5, and turn on the laser 22; Step 2: Control the centering and rotation of the second polarizer 51 in the analyzer 5, control the movement of the optical instrument support platform 83 along the annular guide rail 85, and control the up and down movement of the photoelectric sensor 64 along the lead screw 66, so that the photoelectric sensor 64 can find the exit point of the laser after passing through the birefringent 43 in the semi-cylindrical surface; when the photoelectric sensor 64 detects that the light intensity exceeds the threshold, it is determined that the outgoing light has been captured. Based on the characteristic that the polarization directions of ordinary and extraordinary light are perpendicular, the o-ray and e-ray are separated by the rotation of the second polarizer 51, and the coordinates of their detection points are recorded as follows: and Then we have: o optical refractive index As shown in equation (1): (1); in: The perpendicular distance between the front and back surfaces of a birefringent crystal; The angle of refraction of the o-ray; The angle of incidence; coordinates of the exit point of the e-ray on the back surface of the birefringent crystal. As shown in equation (2): (2); e-ray effective refractive index The relationship conforms to equation (3): (3); in: The angle between the e-ray ray and the optical axis; The angle between the e-wave vector and the optical axis; The angle between the optical axis and the normal to the front surface of the crystal; The angle between the principal section of the crystal and the incident plane; is the principal refractive index of the e-ray.

[0052] Step 3: Control the pressure applicator 7 to apply pressure to the birefringent device 43, control the second polarizer 51 in the analyzer 5 to rotate a certain angle at set time intervals and then stop, and read the data by the photoelectric sensor 64 to draw a polar coordinate graph of light intensity and corresponding polarizer rotation angle in real time.

[0053] Based on the photoelastic effect, external pressure applied to a birefringent material causes a stress distribution within the material. This stress alters the refractive index ellipsoid shape (i.e., induces birefringence or changes the original birefringence), resulting in an additional phase difference (optical path difference) in the light passing through the material, thus changing the polarization state of the emitted light. The intensity of the fittable second harmonic form is derived as follows: ; in: and They are respectively: ; ; The magnitude of the light intensity before it passes through the analyzer; Indicates light intensity I about The function; The angle found between the principal axis of a birefringent crystal and the front surface of the crystal; The phase delay is due to the fast and slow axes of the crystal; Fix the shaft angle of the polarizer; The rotation angle of the analyzer axis; Then, the pressure value applied by the pressure applicator 7 is determined by reverse calculation using a neural network.

[0054] Step 4: Change the voltage between the transparent conductive glass 433 in the birefringent device 43, control the second polarizer 51 in the analyzer 5 to rotate a certain angle at set time intervals and then stop, read the data by the photoelectric sensor 64, draw the polar coordinate diagram of light intensity and corresponding angle in real time, obtain the calculation results including phase difference and light intensity, and then determine the voltage value applied between the transparent conductive glass 433 by back-reasoning through the neural network.

[0055] Step 5: Turn off laser 22 and turn on supplementary light 42. The image captured by camera 31 directly above birefringent device 43 is displayed in real time on touch screen 13. For the homogeneous birefringent material 431, the observed colored stripes originate from the uneven distribution of internal stress. The supplementary light 42 used in this invention is an LED lamp bead, which can emit white light or monochromatic light, and the observed color is actually the color of the entire spectrum superimposed. When white light is incident on birefringent device 43 at a single point, its transmission intensity... for: ; in: It is a wavelength in the visible spectrum; The initial light intensity received at a single point on the lower surface of the birefringent device 43; The optical path difference is the distance between the transmitted light and the transmitted light. , The photoelastic coefficient is That is, the principal stress difference, The thickness of the birefringent device.

[0056] Integrating the spectrum of white light yields the results of white light passing through different optical path differences. When a birefringent device is used, all wavelengths and their intensities that are transmitted ultimately become a color perceived by the human eye, and thus: ; in, For the infinitesimal element in the wavelength integration process; Indicates optical path difference as , wavelength is The intensity of light after it passes through; This represents the relationship between observed colors and the spectrum; It is the maximum wavelength in the visible light spectrum; It is the smallest wavelength in the visible light spectrum.

[0057] Referring to the Michel-Levy spectra, this invention designs spectra based on stress and the thickness of birefringent devices, such as... Figure 11It is worth noting that the thicker the birefringent material 431, the less pronounced the color change. For a given device thickness, by finding the chromatic position corresponding to the observed color, the stress magnitude at that location can be determined.

[0058] In this embodiment, other influencing factors can also be applied to the birefringent device 43 by replacing the module. The second polarizer 51 in the analyzer 5 is controlled to rotate a certain angle at set intervals and then stop. The photoelectric sensor 64 reads the data and draws a polar coordinate diagram of light intensity and corresponding angle in real time to obtain the calculation results including phase difference and light intensity. Then, the corresponding influencing factor values ​​are determined by back-reasoning through a neural network.

[0059] Figure 10 The diagram shows the neural network used in this embodiment. The diagram illustrates the data processing process of the neural network. The 40 sets of light intensity data corresponding to different angles that have been measured are input into the input layer. On the one hand, the data of the input layer is prefitted with the light intensity formula in the form of the second harmonic to obtain an index representing the transformation relationship between the data and the standard harmonic. On the other hand, pooling is performed, that is, the data of the input layer is summarized with less data. Finally, after the analysis of the attention layer, all the data obtained from the previous layer and the data at different time points need to be input together to obtain the relevant information on the change of polarization state, thereby calculating the magnitude of external pressure and optical path difference. Figure 11 The table shown is a comparison of color and stress produced by white light passing through an orthogonal polarizer. After the above calculation process, the upper and lower surfaces are 50... When a thick calcite birefringent material 431 is placed in the device, a colored pattern can be observed in the camera 31. By comparing the position of the color of a point in the pattern with that in the reference table, the magnitude of the axial average stress at that point can be read.

Claims

1. A multidimensional experimental apparatus for a birefringent device, wherein the birefringent material (431) in a birefringent device (43) with a parallelepiped shape is used as the experimental object, the birefringent material (431) birefringently refracts incident light and emits ordinary and extraordinary light, the two emitted beams being parallel in direction and perpendicular in polarization direction, characterized in that: The experimental setup is designed to emit specific types of incident light through the birefringent device (43), detect and obtain the direction, intensity, and polarization direction of ordinary and extraordinary light emitted through the birefringent device (43) to complete a multidimensional experiment and obtain experimental data on refractive index and phase difference. The experimental setup is equipped with a planetary gear optical platform (8), which has an annular guide rail (85) and at least two sets of optical instrument carrier platforms (83) that slide on the annular guide rail (85). A stepper motor (82) for driving the transmission gear (84) to rotate is provided on the optical instrument carrier platform (83). An internal gear base (86) with an internal gear ring is provided at the bottom of the annular guide rail (85). The transmission gear (84) meshes with the internal gear ring in the internal gear base (86) to realize that the optical instrument carrier platform (83) is driven by the stepper motor (82) to move on the annular guide rail (85), and the rotation angle of the optical instrument carrier platform (83) is determined by the rotation angle of the stepper motor. The laser emitter (2) for setting the laser (22) is mounted on one of the optical instrument support platforms (83), so that the laser projected by the laser (22) toward the birefringent device (43) can be adjusted to the set incident angle as the optical instrument support platform (83) moves on the annular guide rail (85); the optical sensor (64) for detecting the light emitted from the birefringent device (43) is set on the lead screw (66) in the light tracking module (6), and can move vertically on the lead screw (66) to adjust the height of the optical sensor (64). The light tracking module (6) is mounted on the other optical instrument support platform (83), so that the optical sensor (64) can rotate around the center of the planetary gear optical platform (8) as the optical instrument support platform (83) moves on the annular guide rail (85), realizing the motion trajectory of the semi-cylindrical surface of the photoelectric sensor (64).

2. The multidimensional experimental apparatus for birefringent devices according to claim 1, characterized in that: in The internal gear base (86) of the planetary gear optical platform (8) is fixedly equipped with a device placement platform (4), a camera module (3), an analyzer (5), and a pressure applicator (7). The device placement platform (4) is used to set up a fill light (42) and place a birefringent device (43). By adjusting the tilt angle of the fill light (42), the left side and front side of the birefringent device (43) are both perpendicular to the horizontal plane. The left side of the birefringent device (43) is the laser incident surface, and the left side of the birefringent device (43) is located at the laser incident surface. At the center of the planetary gear optical platform (8), the right side of the birefringent device (43) is the exit surface; the camera module (3) is used to install the camera (31) so that the camera (31) is directly above the birefringent device (43); the polarizer (5) is a polarizer stepper motor (55) set on the polarizer bracket (54), which rotates the second polarizer (51) through the meshing gear; the pressure applicator (7) is used to apply pressure to the front end of the birefringent device (43).

3. The multidimensional experimental apparatus for birefringent devices according to claim 2, characterized in that: The emitted light from the laser (22) passes through the first polarizer (24) and is incident on the left side of the birefringent device (43). The angle between the direction of the laser and the normal of the left side of the birefringent device (43) is the incident angle. Controlling the stepper motor (82) to rotate can make the laser emitter (2) rotate around the center of the planetary gear optical platform (8) and keep the laser emission direction facing the center of the planetary gear optical platform (8), thereby controlling the change of the incident angle. The birefringent device (43) emits ordinary and unusual light parallel to the incident laser from its right side, and the ordinary and unusual light are incident toward the analyzer (5); The second polarizer (51) adjusts the rotation position of the second polarizer (51) so that the ordinary light and the unusual light emitted from the right side of the birefringent device (43) are emitted as two parallel beams with the same polarization direction as the second polarizer (51) after passing through the second polarizer (51). The photoelectric sensor (64) moves along a semi-cylindrical trajectory to obtain detection signals of the position and intensity of two parallel beams of light, and transmits them to the host computer (11) in the operation terminal (1). The camera (31) is used to capture images of the birefringent device (43) when pressure is applied to the front surface of the birefringent device (43) by the pressure applicator (7) and the light source is emitted by the fill light (42) and projected onto the birefringent device (43). The images are used to analyze the stress magnitude and distribution of the birefringent material (431) in the horizontal direction in the birefringent device (43).

4. The experimental method of the multidimensional experimental apparatus for birefringent devices according to any one of claims 1-3, characterized in that, for The experimental setup is operated according to the following procedure: Step 1: Set the rotation speed and sampling rate of the analyzer (5) and turn on the laser (22). Step 2: Control the centering rotation of the second polarizer (51) in the analyzer (5), control the movement of the optical instrument support platform (83) along the annular guide rail (85), and control the up-and-down movement of the photoelectric sensor (64) along the lead screw (66) so that the photoelectric sensor (64) finds the exit point of the laser after passing through the birefringent (43) in the semi-cylindrical surface; when the photoelectric sensor (64) detects that the light intensity exceeds the threshold, it is determined that the outgoing light has been captured; Based on the characteristic that the polarization directions of ordinary and extraordinary light are perpendicular to each other, the o-ray and e-ray are separated by rotating the second polarizer (51), and the coordinates of their detection points are recorded as follows: and Then we have: o optical refractive index As shown in equation (1): （1）； in: The perpendicular distance between the front and back surfaces of a birefringent crystal; The angle of refraction of the o-ray; Angle of incidence; Coordinates of the exit point of the e-ray from the back surface of the birefringent crystal As shown in equation (2): （2）； e-ray effective refractive index The relationship conforms to equation (3): （3）； in: The angle between the e-ray ray and the optical axis; The angle between the e-wave vector and the optical axis; The principal refractive index of the e-ray; The angle between the optical axis and the normal to the front surface of the crystal; The angle between the principal section of the crystal and the incident plane; Step 3: Control the pressure applicator (7) to apply pressure to the birefringent device (43), control the second polarizer (51) in the analyzer (5) to rotate a certain angle every set time and then stop, read the data by the photoelectric sensor (64), draw the polar coordinate diagram of light intensity and corresponding angle in real time, obtain the calculation results including phase difference and light intensity, and then determine the pressure value applied by the pressure applicator (7) through the neural network. Step 4: Change the voltage between the transparent conductive glass (433) in the birefringent device (43), control the second polarizer (51) in the analyzer (5) to rotate a certain angle every set time and then stop, read the data by the photoelectric sensor (64), draw the polar coordinate diagram of light intensity and corresponding angle in real time, obtain the calculation results including phase difference and light intensity, and then determine the voltage value applied between the transparent conductive glass (433) by reverse calculation through the neural network; Step 5: Turn on the supplementary light (42), observe the diffraction fringes on the upper surface of the birefringent device (43) through the camera (31), calculate the stress distribution in the horizontal direction of the birefringent device (43) based on its brightness and color, and obtain the numerical relationship by interferometric color chart.

5. The experimental method of the multidimensional experimental apparatus for birefringent devices according to claim 4, characterized in that: By replacing the module, other influencing factors are applied to the birefringent device (43). The second polarizer (51) in the analyzer (5) is controlled to rotate a certain angle every set time and then stop. The photoelectric sensor (64) reads the data and draws the polar coordinate diagram of light intensity and corresponding angle in real time. The calculation results including phase difference and light intensity are obtained, and then the corresponding influencing factor values ​​are determined by reverse calculation through the neural network.

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