A waveplate adjustment and measurement method and measuring device

Abstract

This invention provides a waveplate adjustment method, comprising: irradiating an incident light onto a corner bevel prism to obtain a reference reflected light; converging the reference reflected light through a second converging lens to a spot detector to obtain a reference spot; irradiating the incident light onto a waveplate placed on a waveplate placement stage to obtain a measured reflected light; converging the measured reflected light through a second converging lens to a spot detector to obtain a measured spot; adjusting the perpendicularity between the rotation axis of the rotary stage and the waveplate placement stage based on the trajectory of the measured spot as the rotary stage rotates, so that the rotation axis of the rotary stage is perpendicular to the waveplate placement stage; and adjusting the tilt angle of the rotation axis of the rotary stage based on the relative position of the measured spot and the reference spot, so that the rotation axis of the rotary stage is parallel to the optical axis of the incident light. This invention can effectively improve the measurement accuracy of the phase delay of the waveplate, and can intuitively evaluate the error angle identification accuracy of the waveplate and the adjustment accuracy of the adjustment platform, thereby ensuring that the accuracy meets the threshold requirements.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and in particular to a waveplate adjustment and measurement method and measuring device. Background Technology

[0002] Waveplates are a key component in optics, enabling functions such as light modulation, splitting, and rectification. Measuring the phase delay of waveplates has important applications in ensuring polarization control of light, guaranteeing the normal operation of optical devices, and improving the accuracy of physical quantity measurements.

[0003] During the measurement process, the incident light beam needs to be incident perpendicularly onto the surface of the waveplate. Existing technologies typically lack the ability to adjust the waveplate to meet this measurement condition, resulting in low accuracy in measuring the phase delay of the waveplate. Therefore, a waveplate measurement method is needed to improve the accuracy of waveplate phase delay measurement.

[0004] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0005] This invention provides a solution to the technical problem of low accuracy in measuring the phase delay of waveplates due to the lack of effective adjustment methods for waveplates in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a waveplate adjustment method, the waveplate adjustment method being used to adjust an adjustment platform for placing a waveplate, the adjustment platform including a rotary table and a waveplate placement platform connected to the rotary table, the waveplate adjustment method comprising:

[0008] The incident light is irradiated by the corner prism to obtain a reference reflected light, the optical axis of which is parallel to the optical axis of the incident light;

[0009] The reference reflected light is focused onto the spot detector by the second converging lens to obtain the reference spot;

[0010] The incident light is irradiated onto the waveplate placed on the waveplate placement stage to obtain the measured reflected light;

[0011] The measured reflected light is focused onto the spot detector by the second converging lens to obtain the measured spot.

[0012] Based on the trajectory of the measured light spot when the rotary table rotates, the perpendicularity between the rotation axis of the rotary table and the waveplate placement stage is adjusted so that the rotation axis of the rotary table is perpendicular to the waveplate placement stage.

[0013] Based on the relative position of the measured light spot and the reference light spot, the tilt angle of the rotation axis of the rotary stage is adjusted so that the rotation axis of the rotary stage is parallel to the optical axis of the incident light.

[0014] Preferably, the step between obtaining the reference light spot and illuminating the waveplate placed on the waveplate stage with incident light further includes the following steps:

[0015] Adjust the position of the light spot detector so that the reference light spot is located at the center of the light spot detector.

[0016] Preferably, adjusting the perpendicularity between the rotation axis of the rotary table and the waveplate placement stage based on the measured trajectory of the light spot during the rotation of the rotary table, so that the rotation axis of the rotary table is perpendicular to the waveplate placement stage, includes:

[0017] The rotary table is rotated at least one revolution to obtain the trajectory of the measured light spot, which is circular.

[0018] Obtain the center coordinates of the running trajectory and the coordinates of the measured light spot;

[0019] Adjust the perpendicularity between the rotation axis of the rotary table and the waveplate placement stage to move the measured light spot until the distance between the coordinates of the measured light spot and the center coordinates of the running trajectory reaches the minimum recognition distance of the light spot detector.

[0020] Preferably, adjusting the tilt angle of the rotation axis of the rotary stage based on the relative position of the measured light spot and the reference light spot, so that the rotation axis of the rotary stage is parallel to the optical axis of the incident light, includes:

[0021] Obtain the coordinates of the measured light spot and the coordinates of the reference light spot;

[0022] Adjust the tilt angle of the rotation axis of the rotary table to move the measured light spot until the distance between the coordinates of the measured light spot and the coordinates of the reference light spot reaches the minimum recognition distance of the light spot detector.

[0023] Preferably, the adjustment platform further includes a second support base plate, a second adjustment plate connected to the rotary table, and at least three second adjustment screws disposed between the second support base plate and the second adjustment plate;

[0024] The adjustment of the tilt angle of the rotary table's rotation axis includes:

[0025] The tilt angle of the rotary table's rotation axis can be adjusted by changing the distance between the second adjusting plate and the second supporting base plate through the adjustment of the second adjusting screw.

[0026] Secondly, the present invention provides a waveplate measurement method, comprising:

[0027] The adjustment platform is adjusted using the waveplate adjustment method described in the first aspect;

[0028] The phase delay of the waveplate is measured on the adjustment platform.

[0029] Preferably, the following steps are further included between adjusting the adjustment platform and measuring the waveplate placed on the adjustment platform:

[0030] The accuracy of waveplate error angle identification and the adjustment accuracy of adjustment platform are evaluated respectively.

[0031] The evaluation of the accuracy of waveplate error angle identification includes:

[0032] Incident light is irradiated onto a waveplate placed on an adjustment platform to obtain measured reflected light. The measured reflected light is then focused by a second converging lens onto a light spot detector to obtain a measured light spot.

[0033] The minimum identification error angle α of the waveplate is calculated based on the following formula;

[0034] tan2α=Δx / f

[0035] in, Δ x is the minimum recognition distance of the spot detector, and f is the focal length of the second converging lens;

[0036] The minimum identification error angle α is compared with a threshold to ensure that the minimum identification error angle α is less than the threshold.

[0037] The evaluation of the adjustment accuracy of the adjustment platform includes:

[0038] The minimum tilt angle β of the adjustment platform is calculated based on the following formula:

[0039] tanβ=ΔI / L

[0040] in, Δ I is the minimum adjustment distance of the first adjusting screw, and L is the distance from the fulcrum of the first adjusting plate to the first adjusting screw, or... Δ I is the minimum adjustment distance of the second adjusting screw, and L is the distance from the fulcrum of the second adjusting plate to the second adjusting screw.

[0041] The minimum adjustment tilt angle β is compared with a threshold to ensure that the minimum adjustment tilt angle β is less than the threshold.

[0042] Thirdly, the present invention provides a waveplate measuring device, comprising:

[0043] Illumination module, beam splitter, polarization module, adjustment platform, polarization analyzer module, spectral detection module, second converging lens and spot detector;

[0044] The lighting module is used to provide incident light;

[0045] The polarization module, adjustment platform, polarization analyzer, and spectral detection module are sequentially arranged in the optical path of the incident light.

[0046] The adjustment platform is used to place the wave plate, and the incident light can generate reflected light after irradiating the wave plate;

[0047] The beam splitter is placed in the optical path of the reflected light, and the beam splitter is used to reflect the reflected light to the second converging lens;

[0048] The second converging lens is used to converge the reflected light onto the spot detector.

[0049] Preferably, the adjustment platform includes a rotary table and a waveplate placement stage connected to the rotary table, a second support base plate, a second adjustment plate connected to the rotary table, and at least three second adjustment screws placed between the second support base plate and the second adjustment plate; wherein, the waveplate placement stage includes a first support base plate connected to the rotary table, a first adjustment plate, and at least three first adjustment screws placed between the first support base plate and the first adjustment plate.

[0050] In view of the shortcomings of the prior art, the beneficial effects that the present invention can achieve are as follows:

[0051] This invention adjusts the position of the waveplate to ensure that incident light is perpendicularly incident on the surface of the waveplate, effectively improving the measurement accuracy of the phase delay during waveplate phase delay measurement. Furthermore, by using multiple accuracy evaluation methods, this invention can intuitively evaluate the accuracy of waveplate error angle identification and adjustment platform adjustment, ensuring that the accuracy meets the threshold requirements. Furthermore, this invention also provides a waveplate measurement device capable of accurately measuring the phase delay of a waveplate. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0053] Figure 1 This is a schematic flowchart of the waveplate adjustment method in this embodiment;

[0054] Figure 2 This is a schematic diagram of the state when the coordinates of the reference spot coincide with the center of the spot detector during the adjustment process in this embodiment;

[0055] Figure 3 This is a schematic diagram showing the state of the rotary table when its rotation axis is perpendicular to the waveplate placement stage during the adjustment process in this embodiment.

[0056] Figure 4 This is a schematic diagram of the state when the rotation axis of the rotary table is parallel to the optical axis of the incident light during the adjustment process in this embodiment;

[0057] Figure 5 This is a schematic diagram of the structure and measurement process of the waveplate measuring device in this embodiment;

[0058] Figure 6 This is a schematic diagram illustrating the process of evaluating the accuracy of waveplate error angle identification in this embodiment;

[0059] Figure 7 This is a schematic diagram illustrating the process of evaluating the adjustment accuracy of the adjustment platform in this embodiment.

[0060] In the accompanying drawings, the same reference numerals are used to denote the same parts or structures, wherein:

[0061] 10-Illumination module, 101-Light source, 102-Collimating lens; 20-Beam splitter; 30-Polarization module, 301-Polarizer, 302-First compensator, 303-First motor; 40-Waveplate; 50-Adjustment platform, 501-First adjustment plate, 502-First adjustment screw, 503-First support substrate, 504-Rotating stage, 505-Rotation shaft, 506-Second adjustment plate, 507-Second adjustment screw, 508-Second support substrate; 60-Polarization analyzer module, 601-Second motor, 602-Second compensator, 603-Analyzer; 70-Spectrum detection module, 701-First converging lens, 702-Spectrometer; 80-Spot detection module, 801-Second converging lens, 802-Spot detector; 90-Cornered pyramid prism. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined with each other to form feasible technical solutions. Such combinations are not constrained by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0063] Example 1:

[0064] To address the technical problem of low accuracy in waveplate phase delay measurement due to the lack of effective adjustment methods in existing technologies, this embodiment 1 provides a waveplate adjustment method. The method adjusts an adjustment platform on which the waveplate is placed, thereby achieving waveplate adjustment. The adjustment platform includes a rotary table and a waveplate placement platform connected to the rotary table. The rotary table can rotate around its rotation axis, and during the rotation of the rotary table, the waveplate placement platform rotates synchronously. Figure 1 As shown, Figure 1 This is a flowchart illustrating the waveplate adjustment method, which includes:

[0065] S10 causes the incident light to illuminate the corner prism, resulting in a reference reflected light whose optical axis is parallel to the optical axis of the incident light.

[0066] In this step, the incident light can come from the illumination module, which includes components such as a light source and a collimating lens. After the incident light is emitted from the light source, it is collimated by the collimating lens to obtain a parallel beam for detection with good collimation. The optical axis of this parallel beam is the optical axis of the incident light. The corner cube prism is located on the propagation path of the parallel beam. The corner cube prism can reflect the parallel beam back along the original path to obtain the reference reflected light. At this time, the optical axis of the reference reflected light can be made parallel to the optical axis of the incident light.

[0067] S20 causes the reference reflected light to be focused by the second converging lens onto the spot detector to obtain the reference spot.

[0068] The reference reflected light is focused onto the spot detector via a second converging lens. This can be achieved using the reflection function of a beam splitter. The second converging lens and the spot detector can be integrated into a single spot detection module. The second converging lens focuses the reference reflected light, and the spot detector is communicatively connected to a display terminal. The display terminal shows information about the reference spot, while the spot detector receives the reference reflected light. When the reference reflected light enters the spot detector, the reference spot can be observed on the display terminal. Since this reference spot is generated by reference reflected light parallel to the incident light's optical axis, it serves as an indicator of the incident light's optical axis and can be used as a reference for subsequent debugging steps.

[0069] S30, so that the incident light shines on the waveplate placed on the waveplate placement stage, and the measured reflected light is obtained.

[0070] Waveplates are a key component in the field of optics. An important test item for evaluating whether the optical performance of a waveplate meets the requirements is the phase retardation of the waveplate. In order to measure whether the phase retardation of the waveplate meets the requirements, the waveplate is placed on a waveplate placement stage during the measurement. After the incident light shines on the waveplate, the state of the incident light will change, and the measured reflected light is obtained.

[0071] In practical applications, due to minor structural and dimensional errors in the manufacturing of the second converging lens, the waveplate placement stage, and the waveplate itself, the reference light spot may not be centered on the spot detector after the waveplate is placed on the waveplate placement stage. Therefore, in one preferred implementation, between obtaining the reference light spot (corresponding to S20) and illuminating the waveplate placed on the waveplate placement stage with incident light (corresponding to S30), the following step is also included: adjusting the position of the spot detector so that the reference light spot is centered on the spot detector. Adjusting the reference light spot to the center of the spot detector can improve the measurement range of the spot detector and prevent the measured light spot generated by the measured reflected light from falling outside the spot detector.

[0072] like Figure 2 As shown, Figure 2 This is a schematic diagram showing the state when the coordinates of the reference spot coincide with the center of the spot detector during the adjustment process.

[0073] S40 causes the measured reflected light to be focused by the second converging lens onto the light spot detector, thus obtaining the measured light spot.

[0074] In S40, the formation process of the measured light spot is basically similar to that of the reference light spot in S20. In this step, the formation process of the measured light spot will not be described again.

[0075] S50, based on the measured trajectory of the light spot when the rotary table rotates, adjusts the perpendicularity between the rotary table's rotation axis and the waveplate placement stage so that the rotary table's rotation axis is perpendicular to the waveplate placement stage.

[0076] In this step, based on the measured trajectory of the light spot during the rotation of the rotary table, the perpendicularity between the rotation axis of the rotary table and the waveplate placement stage is adjusted so that the rotation axis of the rotary table is perpendicular to the waveplate placement stage. Specifically, this includes:

[0077] S51, rotate the rotary table at least one revolution to obtain the running trajectory of the measured light spot. The running trajectory is circular. This is because when the waveplate surface and the rotation axis of the rotary table are not perpendicular, the angle between the waveplate surface and the incident light will change periodically with the rotation of the rotary table during the rotation of the rotary table. As a result, the measured light spot will also undergo periodic displacement with the rotation of the rotary table, eventually forming a circular running trajectory.

[0078] S52, obtain the center coordinates of the running trajectory and the coordinates of the measured light spot.

[0079] Since the trajectory of the measured light spot is circular, in this step, the center coordinates of the trajectory specifically refer to the center coordinates of the trajectory of the measured light spot. Correspondingly, the coordinates of the measured light spot, especially the center coordinates of the measured light spot.

[0080] S53, adjust the perpendicularity between the rotation axis of the rotary table and the waveplate placement stage to move the measured light spot until the distance between the coordinates of the measured light spot and the center coordinates of the running trajectory reaches the minimum recognition distance of the light spot detector. This is because when the waveplate surface and the rotation axis of the rotary table are completely perpendicular, the angle between the waveplate surface and the incident light no longer changes as the rotary table rotates. At this time, the measured light spot generated by the incident light will appear as a light point, and the position of this light point is the center (center) of the circular running trajectory. Therefore, by adjusting the coordinates of the measured light spot to coincide with the center coordinates of the running trajectory, the perpendicularity between the waveplate surface and the rotation axis of the rotary table can be satisfied. The specific steps to make the distance between the coordinates of the measured light spot and the center coordinates of the running trajectory reach the minimum recognition distance of the light spot detector include the following:

[0081] Let the coordinates of the center of the incident light spot trajectory ring before adjustment be (x1, y1), and the coordinates after adjustment be (x2, y2). The minimum recognition capability of the spot detector is 0.01 mm, which can be obtained from the technical parameters of the spot detector. The 0.01 mm given here is merely an example. When |x2-x1|≤0.01 mm and |y2-y1|≤0.01 mm, the distance between the measured spot coordinates and the center coordinates of the trajectory reaches the minimum recognition distance of the spot detector. At this point, the measured spot coordinates and the center coordinates of the trajectory are essentially coincident.

[0082] like Figure 3 As shown, Figure 3 This is a schematic diagram showing the state when the rotation axis of the rotary table is perpendicular to the waveplate placement stage during the adjustment process.

[0083] S60, based on the relative position of the measured light spot and the reference light spot, adjust the tilt angle of the rotation axis of the rotary stage so that the rotation axis of the rotary stage is parallel to the optical axis of the incident light.

[0084] Based on the relative positions of the measured light spot and the reference light spot, the tilt angle of the rotation axis of the rotary stage is adjusted so that the rotation axis of the rotary stage is parallel to the optical axis of the incident light. Specifically, this includes:

[0085] S61, obtain the coordinates of the measured spot and the coordinates of the reference spot.

[0086] S62, adjust the tilt angle of the rotary table's rotation axis to move the measured light spot until the distance between the coordinates of the measured light spot and the coordinates of the reference light spot reaches the minimum recognition distance of the light spot detector. The adjustment steps involved in S61 and S62 are basically the same as those described in S53 above, so they will not be elaborated further here. When the measured light spot coincides with the reference light spot, the reflected light corresponding to the measured light spot is the reference reflected light perpendicular to the incident light axis. Since the reflected light is parallel to the incident light, it indicates that the waveplate surface is now perpendicular to the incident light.

[0087] like Figure 4 As shown, Figure 4 This is a schematic diagram showing the state when the rotation axis of the rotary table is parallel to the optical axis of the incident light during the adjustment process.

[0088] It should be noted that in practical applications, the order of S50 and S60 can be interchanged. However, based on current practical applications and verification, placing S50 before S60 is the optimal order in actual operation. Once both steps S50 and S60 are completed, the technical effect of ensuring that the incident light always strikes the surface of the waveplate perpendicularly as the waveplate rotates with the adjustment platform can be achieved, thereby guaranteeing the accuracy of the waveplate's phase delay measurement.

[0089] The waveplate placement stage includes a first support base plate connected to the rotary table, a first adjustment plate, and at least three first adjustment screws placed between the first support base plate and the first adjustment plate. In actual application, the waveplate is placed on the first adjustment plate, and adjusting any one of the first adjustment screws can adjust the perpendicularity between the rotary table rotation axis and the waveplate placement stage. Specifically, the perpendicularity between the rotary table rotation axis and the waveplate placement stage refers to the perpendicularity between the rotary table rotation axis and the first adjustment plate.

[0090] In addition to the aforementioned rotary table and waveplate placement stage connecting the rotary table, the adjustment platform, in one preferred embodiment, further includes a second support base plate, a second adjustment plate connecting the rotary table, and at least three second adjustment screws positioned between the second support base plate and the second adjustment plate for adjusting the tilt angle of the rotary table's rotation axis; specifically:

[0091] Adjusting the tilt angle of the rotary table's rotation axis includes:

[0092] The tilt angle of the rotary table's rotation axis is adjusted by changing the distance between the second adjusting plate and the second supporting base plate through the adjustment of the second adjusting screw.

[0093] This embodiment 1 provides a waveplate adjustment method. By adjusting the position of the waveplate, the incident light can be perpendicularly incident on the surface of the waveplate, which can effectively improve the measurement accuracy of the phase delay of the waveplate during the phase delay measurement process.

[0094] Example 2:

[0095] Based on Example 1, Example 2 provides a waveplate measurement method, including: adjusting an adjustment platform by using the waveplate adjustment method of Example 1; and then measuring the waveplate placed on the adjustment platform to obtain the phase delay of the waveplate.

[0096] When performing a waveplate phase delay measurement, the light propagation path follows... Figure 1 The propagation method of the dual-rotation ellipsometer (other ellipsometers such as the single-rotation ellipsometer are also feasible) is as follows: the incident light from the light source passes through the collimating lens, is transmitted by the beam splitter, and is then incident parallel to the polarizer and the first compensator (driven and controlled by the motor in the polarization module), and then incident on the surface of the waveplate to be measured. The waveplate is placed on the adjustment platform or adsorbed on the adjustment platform. The light transmitted from the waveplate passes through the second compensator (driven and controlled by the motor in the analyzer module) and the analyzer, and is then focused by the converging lens to be received by the spectrometer.

[0097] The phase retardation of the waveplate can be calculated by acquiring its spectrum using a spectrometer, performing spectral analysis, and combining this with appropriate data processing. For example, Figure 1 In this embodiment, the phase delay of the waveplate under test is obtained by acquiring the Mueller matrix spectrum and utilizing the relationship between the Mueller matrix and the phase and amplitude parameters. To ensure that the measurement accuracy of the waveplate's phase delay meets the threshold requirement, the following steps are included between adjusting the adjustment platform and measuring the waveplate placed on the adjustment platform: evaluating the error angle identification accuracy of the waveplate and the adjustment accuracy of the adjustment platform, respectively.

[0098] like Figure 6 As shown, Figure 6This is a schematic diagram illustrating the process of evaluating the accuracy of waveplate error angle identification. The evaluation of waveplate error angle identification accuracy includes:

[0099] The incident light is irradiated by a waveplate placed on an adjustment platform to obtain the measured reflected light. The measured reflected light is then focused by a second converging lens onto a light spot detector to obtain the measured light spot.

[0100] The minimum identification error angle α of the waveplate is calculated based on the following formula. Here, the minimum error angle α refers to the angle between the surface of the waveplate and the reference plane of the waveplate, with the center of the waveplate as the fulcrum. Here, the reference plane of the waveplate refers to the plane in which the waveplate is located when the surface of the waveplate is perpendicular to the incident light.

[0101] tan2α=Δx / f

[0102] in, Δ x is the minimum recognition distance of the spot detector, and f is the focal length of the second converging lens;

[0103] The minimum recognition error angle α is compared with the threshold to ensure that the minimum recognition error angle α is less than the threshold.

[0104] To illustrate with a practical application scenario, let's define the minimum recognition distance of the light spot detector. Δ x = 0.01mm, the focal length of the second converging lens is selected as F90, that is: f = 90mm, which is converted to α≈12.73″, which is better than the threshold 1′, that is, the error angle recognition accuracy of the waveplate meets the threshold requirement.

[0105] like Figure 7 As shown, Figure 7 This is a schematic diagram illustrating the process of evaluating the adjustment accuracy of the adjustment platform. The evaluation of the adjustment accuracy of the adjustment platform includes:

[0106] The minimum tilt angle β of the adjustment platform is calculated based on the following formula:

[0107] tanβ=ΔI / L

[0108] in, Δ I represents the minimum adjustment distance of the first adjusting screw, which is the distance adjusted by rotating the first adjusting screw one revolution. L represents the distance from the fulcrum of the first adjusting plate to the first adjusting screw, or... Δ I represents the minimum adjustment distance of the second adjusting screw, which is the distance adjusted by rotating the second adjusting screw one revolution. L represents the distance from the fulcrum of the second adjusting plate to the second adjusting screw. In this invention, the fulcrum is usually another adjusting screw.

[0109] The minimum adjustment tilt angle β is compared with the threshold to ensure that the minimum adjustment tilt angle β is less than the threshold.

[0110] To illustrate with a practical application scenario, let's assume the minimum adjustment distance of the first adjusting screw is... Δ I = 0.025 mm, and the distance from the fulcrum of the first adjusting plate to the first adjusting screw is L = 100 mm. This translates to β ≈ 0.86′, which is better than the threshold 1′. Therefore, the adjustment accuracy of the adjusting platform meets the threshold requirement.

[0111] This embodiment 2 provides a waveplate measurement method. By using multiple accuracy evaluation methods, the error angle identification accuracy of the waveplate and the adjustment accuracy of the adjustment platform can be intuitively evaluated, ensuring that the phase delay measurement accuracy of the waveplate meets the threshold requirements.

[0112] Example 3:

[0113] Based on Embodiment 2, Embodiment 3 provides a waveplate measuring device, such as... Figure 5 As shown, Figure 5 This is a schematic diagram of the structure and measurement process of a waveplate measuring device, including: an illumination module 10, a beam splitter 20, a polarization module 30, an adjustment platform 50, an analyzer module 60, a spectral detection module 70, a second converging lens 801, and a spot detector 802 (spot detection module 80); the illumination module 10 provides incident light, and the polarization module 30, adjustment platform 50, analyzer module 60, and spectral detection module 70 are sequentially arranged in the optical path of the incident light; the adjustment platform 50 is used to place the waveplate 40, which is not part of the device itself, but the incident light can generate reflected light after illuminating the waveplate 40; the beam splitter 2 ...2); the second converging lens 40 provides incident light, and the third converging lens 40 provides incident light, and the fourth converging lens 40 is used to measure the waveplate 40; the fifth converging lens 40, a second converging lens 801, and a spot detector 802 (spot detection module 802); the sixth converging lens 40 provides incident light, and the seventh converging lens 40 provides incident light, and the fifth converging lens 40 provides incident light, and the sixth converging lens 40 provides incident light, and the The optical mirror 20 is placed in the optical path of the reflected light. The beam splitter 20 has transmission and reflection functions, which are used to transmit the incident light to the polarizing module 30 and reflect the reflected light to the second converging lens 801. The second converging lens 801 is used to converge the reflected light to the spot detector 802, thereby realizing the visualization of the reference spot or the measured spot. The spot detector 802 can be selected as a position sensitive detector (i.e., PSD), a four-quadrant detector (i.e., QD) or a charge-coupled device (i.e., CCD). In practical applications, the spot detector 802 is preferably a four-quadrant detector (i.e., QD) for more intuitive and convenient use.

[0114] In a specific implementation, the illumination module 10 includes a light source 101 and a collimating lens 102. The incident light is emitted from the light source 101, collimated by the collimating lens 102, and then enters the polarization module 30. The polarization module 30 includes a polarizer 301, a first compensator 302, and a first motor 303. The first motor 303 is used to drive the first compensator 302. Similarly, the polarization detection module 60 includes a second motor 601, a second compensator 602, and a polarizer 603. The second motor 601 is used to drive the second compensator 602.

[0115] The adjustment platform 50 is a high-precision mechanical structure, comprising a rotary table 504, a waveplate placement platform connected to the rotary table 504, a second support base plate 508, a second adjustment plate 506 connected to the rotary table 504, and at least three second adjustment screws 507 placed between the second support base plate 508 and the second adjustment plate 506. The waveplate placement platform includes a first support base plate 503 connected to the rotary table 504, a first adjustment plate 501, and at least three first adjustment screws 502 placed between the first support base plate 503 and the first adjustment plate 501. In practical applications, the rotary table 504 can rotate around its rotation axis 505. When the rotary table 504 rotates, the waveplate placement platform (i.e., the first support base plate 503, the first adjustment plate 501, and the first adjustment screws 502) rotate synchronously. When connecting to the polarization detection module 60, the second support base plate 508 is fixedly connected to the housing of the second motor 601 through holes provided in the second support base plate 508.

[0116] The spectral detection module 70 includes a first converging lens 701 and a spectrometer 702. The incident light is converged by the first converging lens 701 and then received by the spectrometer 702.

[0117] This embodiment 3 provides a waveplate measuring device that can accurately measure the phase delay of a waveplate, and has the advantages of convenient operation, high measurement efficiency, and high measurement accuracy.

[0118] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

Claims

1. A waveplate adjustment method, characterized in that: The waveplate adjustment method is used to adjust an adjustment platform for placing waveplates. The adjustment platform includes a rotary table and a waveplate placement platform connected to the rotary table. The waveplate adjustment method includes: The incident light is irradiated by the corner prism to obtain a reference reflected light, the optical axis of which is parallel to the optical axis of the incident light; The reference reflected light is focused onto the spot detector by the second converging lens to obtain the reference spot; The incident light is irradiated onto the waveplate placed on the waveplate placement stage to obtain the measured reflected light; The measured reflected light is focused onto the spot detector by the second converging lens to obtain the measured spot. Based on the measured trajectory of the light spot during the rotation of the rotary table, the perpendicularity between the rotation axis of the rotary table and the waveplate placement stage is adjusted so that the rotation axis of the rotary table is perpendicular to the waveplate placement stage; specifically including: The rotary table is rotated at least one revolution to obtain the trajectory of the measured light spot, which is a circular trajectory. Obtain the center coordinates of the running trajectory and the coordinates of the measured light spot; Adjust the perpendicularity between the rotation axis of the rotary table and the waveplate placement stage to move the measured light spot until the distance between the coordinates of the measured light spot and the center coordinates of the running trajectory reaches the minimum recognition distance of the light spot detector. Based on the relative position of the measured light spot and the reference light spot, the tilt angle of the rotation axis of the rotary stage is adjusted so that the rotation axis of the rotary stage is parallel to the optical axis of the incident light, specifically including: Obtain the coordinates of the measured light spot and the coordinates of the reference light spot; Adjust the tilt angle of the rotation axis of the rotary table to move the measured light spot until the distance between the coordinates of the measured light spot and the coordinates of the reference light spot reaches the minimum recognition distance of the light spot detector.

2. The waveplate adjustment method according to claim 1, characterized in that... Between obtaining the reference light spot and illuminating the waveplate placed on the waveplate stage with incident light, the following steps are also included: Adjust the position of the light spot detector so that the reference light spot is located at the center of the light spot detector.

3. The waveplate adjustment method according to claim 1 or 2, characterized in that: The adjustment platform further includes a second support base plate, a second adjustment plate connected to the rotary table, and at least three second adjustment screws placed between the second support base plate and the second adjustment plate. The adjustment of the tilt angle of the rotary table's rotation axis includes: The tilt angle of the rotary table's rotation axis can be adjusted by changing the distance between the second adjusting plate and the second supporting base plate through the adjustment of the second adjusting screw.

4. A waveplate measurement method, characterized in that, include: The adjustment platform is adjusted using the waveplate adjustment method as described in any one of claims 1-3; The phase delay of the waveplate is measured on the adjustment platform.

5. The waveplate measurement method according to claim 4, characterized in that, Between adjusting the adjustment platform and measuring the waveplate placed on the adjustment platform, the following steps are also included: The accuracy of waveplate error angle identification and the adjustment accuracy of adjustment platform are evaluated respectively. The evaluation of the accuracy of waveplate error angle identification includes: Incident light is irradiated onto a waveplate placed on an adjustment platform to obtain measured reflected light. The measured reflected light is then focused by a second converging lens onto a light spot detector to obtain a measured light spot. The minimum identification error angle α of the waveplate is calculated based on the following formula; tan2α= x / f in, x is the minimum recognition distance of the spot detector, and f is the focal length of the second converging lens; The minimum identification error angle α is compared with a threshold to ensure that the minimum identification error angle α is less than the threshold. The evaluation of the adjustment accuracy of the adjustment platform includes: The minimum tilt angle β of the adjustment platform is calculated based on the following formula: tanβ= I / L in, I is the minimum adjustment distance of the first adjusting screw, and L is the distance from the fulcrum of the first adjusting plate to the first adjusting screw, or... I is the minimum adjustment distance of the second adjusting screw, and L is the distance from the fulcrum of the second adjusting plate to the second adjusting screw. The minimum adjustment tilt angle β is compared with a threshold to ensure that the minimum adjustment tilt angle β is less than the threshold.

6. A waveplate measuring device, characterized in that, include: Illumination module, beam splitter, polarization module, adjustment platform, polarization analyzer module, spectral detection module, second converging lens and spot detector; The lighting module is used to provide incident light; The polarization module, adjustment platform, polarization analyzer and spectral detection module are sequentially arranged in the optical path of the incident light. The spectral detection module includes a first converging lens and a spectrometer. The incident light is converged by the first converging lens and then received by the spectrometer. The adjustment platform is used to place the wave plate, and the incident light can generate reflected light after irradiating the wave plate; The adjustment platform includes a rotary table, a waveplate placement platform connected to the rotary table, a second support base plate, a second adjustment plate connected to the rotary table, and at least three second adjustment screws placed between the second support base plate and the second adjustment plate; wherein, the waveplate placement platform includes a first support base plate connected to the rotary table, a first adjustment plate, and at least three first adjustment screws placed between the first support base plate and the first adjustment plate. The beam splitter is placed in the optical path of the reflected light, and the beam splitter is used to reflect the reflected light to the second converging lens; The second converging lens is used to converge the reflected light onto the spot detector.

Images