Optical module alignment method and alignment system

Abstract

The embodiment of the application provides an optical module alignment method and an alignment system. The optical module alignment method is applied to an optical module alignment system. The alignment system comprises a light source assembly, a phase delay element, a polarizer and a detection module. The optical module to be aligned is arranged between the light source assembly and the phase delay element. The alignment method comprises the following steps: controlling polarized light of multiple fields of view to be projected to the detection module in sequence through the optical module to be aligned, the phase delay element and the polarizer; acquiring a polarization parameter of light emitted by the optical module to be aligned according to the intensity of light emitted by the polarizer and received by the detection module; determining an optical axis angle of the optical film to be aligned according to the polarization parameter; acquiring a straight edge angle of the lens to be aligned, wherein the straight edge angle is the angle between the straight edge of the lens and a reference line, and the reference line is a coordinate axis in the vertical direction in the vision camera coordinate system; and rotating the optical film to be aligned based on the polarization parameter and the straight edge angle to realize the alignment of the optical module.

Description

Technical Field

[0001] This application relates to the field of optical module testing technology, and more specifically, to an optical module alignment method and alignment system. Background Technology

[0002] The optical film is a crucial component of the VR Pancake (folded optical path). The ability of the lens to refract light multiple times after being bonded to the optical film is a key factor in making VR devices more portable. The bonding precision of the optical film plays a vital role in the image quality of the VR Pancake; even minute deviations in the bonding angle can severely impact image quality.

[0003] Currently, one method of applying VR Pancake film is to align the physical reference of the optical film with the reference visual alignment of the lens. However, this method introduces significant errors, which may seriously affect the imaging quality of VR Pancake.

[0004] Therefore, precise alignment technology of the optical axis is needed to reduce cost losses in the film application process and improve product yield, thereby ensuring the visual effect of VR Pancake and the user's eye comfort, and enhancing the user's immersive virtual experience. Summary of the Invention

[0005] The purpose of this application is to provide a new technical solution for an optical module alignment method and alignment system.

[0006] In a first aspect, this application provides an optical module alignment method. The optical module alignment method is applied to an optical module alignment system, which includes: a light source assembly, a phase retardation element, a polarizer, and a detection module. The phase retardation element rotates at an angular frequency ω, and the light source assembly and the phase retardation element are positioned between them for setting an optical module to be aligned. The optical module to be aligned includes a lens to be aligned and an optical film to be aligned, the optical film being rotatable relative to the lens to be aligned. When the optical module to be aligned is positioned between the light source assembly and the phase retardation element, the alignment system further includes a vision camera.

[0007] The optical module alignment method includes:

[0008] Polarized light controlling multiple fields of view is sequentially projected onto the detection module through the optical module to be aligned, the phase delay element, and the polarizer;

[0009] Based on the intensity of the polarizer-emitted light received by the detection module, the polarization parameters of the light emitted by the optical module to be aligned are obtained.

[0010] The optical axis angle of the optical film to be aligned is determined based on the polarization parameters.

[0011] Obtain the straight edge angle of the lens to be aligned, wherein the straight edge angle is the angle between the straight edge of the lens and the reference line, and the reference line is the vertical coordinate axis in the visual camera coordinate system;

[0012] The optical film to be aligned is rotated based on the polarization parameters and the straight edge angle to achieve the alignment of the optical module.

[0013] Optionally, the optical film is one of a polarizing film, a reflective polarizing film, or a phase retardation film.

[0014] Optionally, when the optical film to be aligned is a phase retardation film, the polarization parameters of the light emitted from the polarizer received by the detection module are obtained as azimuth angle and ellipticity.

[0015] Optionally, when the optical film to be aligned is a polarizing film or a reflective polarizing film, the polarization parameter of the light emitted from the optical module to be aligned is obtained as the azimuth angle based on the intensity of the light emitted from the polarizer received by the detection module.

[0016] Optionally, the phase delay element is a quarter-wave plate, and the polarizer is a horizontal linear polarizer.

[0017] Optionally, the light source assembly includes a polarizer, and when the optical film to be aligned is a phase retardation film, it further includes the following before the polarized light controlling multiple fields of view passes through the optical module to be aligned:

[0018] The angle of the polarizer is controlled to be the ideal optical axis angle of the phase retardation film under test.

[0019] Optionally, obtaining the polarization parameters of the light emitted from the optical module to be aligned, based on the intensity of the light emitted from the polarizer received by the detection module, specifically includes:

[0020] The intensity of the light emitted from the polarizer is obtained when the angle between the fast axis of the phase delay element and the horizontal direction is α, where α = ωt, and t is the rotation time of the phase delay element;

[0021] Based on the intensity of the light emitted from the polarizer, the Stokes vector of the light emitted from the optical module to be aligned is obtained;

[0022] The polarization parameters of the emitted light from the optical module to be aligned are obtained based on the Stokes vector of the emitted light from the optical film to be aligned.

[0023] Optionally, obtaining the Stokes vector of the light emitted from the optical module to be aligned, based on the intensity of the light emitted from the polarizer, specifically includes:

[0024] A model is established to determine the relationship between the intensity of the light emitted from the polarizer and the Stokes vector of the light emitted from the optical module to be aligned.

[0025] Perform a Fourier transform on the relationship model and obtain the Fourier transform coefficients based on the intensity of the light emitted from the polarizer;

[0026] Based on the Fourier transform coefficients, the Stokes vector of the emitted light from the optical module to be aligned is obtained.

[0027] Optionally, the model for obtaining the relationship between the intensity of the light emitted from the polarizer and the Stokes vector of the light emitted from the optical film to be aligned specifically includes:

[0028] The Stokes vector of the light emitted from the optical module to be aligned is set as Sm;

[0029] Based on the Stokes vector Sm, obtain the Stokes vector S′ of the emitted light from the phase delay element;

[0030] Based on the Stokes vector S′, obtain the Stokes vector Sout of the polarizer-emitted light;

[0031] Based on the Stokes vector Sout, a relationship model is obtained between the intensity of the light emitted from the polarizer and the Stokes vector of the light emitted from the optical module to be aligned.

[0032] Optionally, according to the Stokes vector S m Obtaining the Stokes vector S′ of the emitted light from the phase delay element specifically includes:

[0033] According to the Stokes vector S m The Stokes vector S′ of the emitted light from the phase delay element is obtained by taking the Mueller matrix of the phase delay element, which has an angle α between the fast axis and the horizontal direction.

[0034] Optionally, obtaining the Stokes vector Sout of the polarizer-emitted ray based on the Stokes vector S′ specifically includes:

[0035] The Stokes vector Sout of the polarizer's outgoing light is obtained based on the Stokes vector S′ and the Mueller matrix of the polarizer.

[0036] Optionally, the phase delay element rotating at an angular frequency ω specifically includes:

[0037] The phase delay element is driven by a stepper motor to rotate at an angular frequency ω, where the number of steps of the stepper motor is n, the step size is aj, and α = ωt = n × aj.

[0038] Secondly, an optical module alignment system is provided, the alignment system comprising:

[0039] The light source assembly, phase delay element, polarizer and detection module, wherein the phase delay element rotates at an angular frequency ω; between the light source assembly and the phase delay element is a space for placing an optical module to be aligned, the optical module to be aligned including an alignment lens and an alignment optical film, the alignment optical film rotating relative to the alignment lens.

[0040] The light source assembly is used to emit polarized light with multiple fields of view;

[0041] When the optical module to be aligned is placed between the light source assembly and the phase delay element, the optical module to be aligned, the phase delay element, the polarizer and the detection module are arranged sequentially along the same optical axis, and the vision camera is located above the lens to be aligned.

[0042] Optionally, the light source assembly includes: a light source, a fast reflector, a lens group, and a polarizer, wherein the lens group includes at least one lens;

[0043] The light emitted from the light source passes sequentially through the fast reflector, the lens group, and the polarizer before being projected onto the optical module under test.

[0044] Optionally, it also includes a stepper motor that drives the phase delay element to rotate at an angular frequency ω.

[0045] Optionally, the polarizer is a horizontal linear polarizer, and the phase delay element is a quarter-wave plate.

[0046] In the technical solution provided in this application embodiment, the optical axis angle of the optical film is determined by calculating the polarization parameters of the light emitted from the optical module, and the straight edge angle of the lens is obtained by the vision camera. By rotating the optical film, the optical axis angle of the optical film and the straight edge angle of the lens are aligned, thereby achieving precise alignment of the optical film and the lens in the optical module.

[0047] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0048] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0049] Figure 1 The diagram shown is a structural diagram of the optical module alignment system provided in an embodiment of this application.

[0050] Explanation of reference numerals in the attached figures:

[0051] 1. Light source assembly; 10. Light source; 11. Fast reflector; 12. First lens; 13. Second lens; 14. Polarizer;

[0052] 2. Optical module to be aligned; 21. Lens to be aligned; 22. Optical film to be aligned;

[0053] 3. Phase delay element;

[0054] 4. Polarizer;

[0055] 5. Detection module;

[0056] 6. Visual camera. Detailed Implementation

[0057] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0058] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0059] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0060] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0061] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0062] Polarizing films are an important component of VR Pancakes. The polarizing films used in VR Pancakes mainly include POL (polarizing film), RP (reflective polarizing film), and QWP (quarter-phase retardation film). Among them, POL (polarizing film) and RP (reflective polarizing film) are used to selectively reflect and transmit polarized light, while QWP (quarter-phase retardation film) is used to convert the polarization state of the light beam, enabling the light to switch between circularly polarized and linearly polarized light.

[0063] The commonly used alignment method is to use the physical reference of the optical film and the reference visual alignment of the lens. However, this method introduces a large error, deviating from the ideal state by 1° to 2°, which may seriously affect the imaging quality of VR Pancake.

[0064] To address the aforementioned technical issues, this application provides a novel alignment method and system for optical modules, enabling rapid and precise alignment of optical modules. Specifically, the alignment method and system provided in this application can achieve accurate alignment of optical films and lenses within the optical module.

[0065] The optical module alignment method and alignment system provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0066] According to one embodiment of this application, an optical module alignment method is provided, specifically a method for achieving precise alignment between the polarization axis of the optical film and the lens in a VR Pancake solution. This optical module alignment method is applied to an optical module alignment system. (Refer to...) Figure 1 The alignment system includes: a light source assembly 1, a phase delay element 3, a polarizer 4, and a detection module 5. The phase delay element 3 rotates at an angular frequency ω. The light source assembly 1 and the phase delay element 2 are used to set up an optical module 2 to be aligned. The optical module 2 to be aligned includes an alignment lens 21 and an alignment optical film 22. The alignment optical film 22 is rotatable relative to the alignment lens 21.

[0067] When the optical module 2 to be aligned is disposed between the light source assembly 1 and the phase delay element 3, the detection system further includes a vision camera 6;

[0068] The optical module optical axis alignment method includes the following:

[0069] Step 1: Control the polarized light from multiple fields of view to pass sequentially through the optical module to be aligned 2, the phase delay element and the polarizer and project it onto the detection module;

[0070] Step 2: Based on the intensity of the light emitted from the polarizer received by the detection module, obtain the polarization parameters of the light emitted from the optical module 2 to be aligned;

[0071] Step 3: Determine the optical axis angle of the optical film 22 to be aligned based on the polarization parameters of the emitted light from the optical module 2 to be aligned;

[0072] Step 4: Obtain the straight edge angle of the lens 21 to be aligned, wherein the straight edge angle is the angle between the straight edge of the lens and the reference line, and the reference line is the vertical coordinate axis in the visual camera coordinate system;

[0073] Step 5: Rotate the optical film based on the polarization parameters and the straight edge angle to align the optical module.

[0074] According to the optical module alignment method provided in this application embodiment, the optical module to be aligned is placed between the light source assembly 1 and the phase delay element 3, and the lenses and optical films in the optical module are precisely aligned. The polarized light emitted from the light source assembly 1 can first pass through the optical film, and then through the lens to the phase delay element 3, or the polarized light emitted from the light source assembly 1 can first pass through the lens, and then through the optical film to the phase delay element 3. In this embodiment, the arrangement order of the lenses and optical films is not limited.

[0075] Specifically, the polarization parameters of the light emitted from the optical module are detected by a combination of a phase delay element 3 rotating at an angular frequency ω, a polarizer 4, and a detection module 5. Based on these polarization parameters, the optical axis angle of the optical film is determined, and the right-angle angle of the lens is acquired via a vision camera 6. Precise alignment of the optical module is achieved based on the optical axis angle of the optical film and the right-angle angle of the lens. For example, if the optical axis angle of the optical film relative to the right-angle angle of the lens to be aligned is 1°, but the desired angle is 0°, the optical film can be rotated to adjust its optical axis angle until the right-angle angle relative to the lens is 0°, thus achieving precise alignment of the optical module.

[0076] In step 1, polarized light from multiple fields of view is sequentially projected onto the detection module 5 through the alignment optical module, the phase retardation element 3, and the polarizer 4. For example, the optical module includes an alignment lens and an alignment optical module. The light source assembly 1 emits linearly polarized light from multiple fields of view, which sequentially passes through the alignment lens, the alignment optical film, the phase retardation element 3, and the polarizer 4, and is finally received by the detection module 5. For example, the detection module 5 can be a CCD camera.

[0077] In one specific embodiment, the optical film is a POL film or an RP film. The light source assembly generates linearly polarized light with multiple fields of view, which sequentially passes through the alignment lens and the alignment POL or RP film, where the POL and RP films selectively reflect and transmit polarized light. Therefore, the polarized light transmitted through the POL or RP film is also linearly polarized. An electric rotary wheel rotates the alignment POL or RP film, and the outgoing light from the POL or RP film then passes through a phase delay element and a polarizer rotating at an angular frequency ω, and finally is received by a CCD.

[0078] In another specific embodiment, the optical film is a QWP film. The light source assembly generates linearly polarized light with multiple fields of view, which is then incident on the alignment lens and the alignment QWP film, where the QWP film is used to convert the polarization state of the light beam. Therefore, the polarized light transmitted through the QWP film can be linearly polarized, circularly polarized, or elliptically polarized. An electric rotating wheel can drive the alignment QWP film to rotate. When the incident linearly polarized light passes through the alignment QWP film, it exits as linearly polarized light when its fast axis is aligned with the QWP film; otherwise, it exits as elliptically polarized light. The exiting light then passes through a phase delay element 3 rotating at an angular frequency ω and a polarizer 4, and is finally received by a CCD.

[0079] In step 2, the polarization parameters of the light emitted from the polarizer 4 are obtained based on the intensity of the light received by the detection module 5. These polarization parameters can be the azimuth angle of the light emitted from the optical module, and / or the ellipticity of the light emitted from the optical module. The azimuth angle of the optical module's emission direction is the angle between the polarized light emitted from the optical module and the horizontal axis.

[0080] In this step, the azimuth angle of the light emitted from the polarizer 4 is obtained based on the Stokes vector and the Mueller matrix by detecting the intensity of the light emitted from the optical film received by the detection module 5. Specifically, when the fast axis of the phase delay element 3 makes an angle of α (α = ωt) with the horizontal direction, and the polarizer 4 emits polarized light from multiple fields of view, the polarization parameters of the polarized light emitted from the optical module are calculated based on the Stokes vector and the Mueller matrix according to the intensity of the polarized light from the multiple fields of view emitted from the polarizer 4 detected by the detection module 5.

[0081] In step 3, the optical axis angle of the optical film is determined based on the polarization parameters of the light emitted from the optical module. Specifically, the optical axis angle of the optical film to be aligned is determined based on the polarization parameters of the light emitted from the optical film to be aligned.

[0082] In one example, the optical module includes a lens to be aligned 21 and an optical film to be aligned 22, with the optical film 22 positioned closer to the phase retardation element 3 than the lens to be aligned 21. The optical film to be aligned is either a POL film or an RP film. Based on the intensity of the polarized light emitted from the polarizer 4 in multiple fields of view detected by the detection module 5, the azimuth angle of the polarized light emitted from the optical module is calculated based on the Stokes vector and the Mueller matrix. The optical axis angle of the optical film to be aligned is then determined based on the azimuth angle of the polarized light emitted from the optical module. Specifically, regardless of the type of polarized light emitted from the light source assembly, based on the principle that the POL film or RP film transmits and blocks polarized light in a specific direction, the vibration direction of the light vector of the polarized light emitted from the POL film or RP film must be consistent with the transmission axis direction of the POL film or RP film. Therefore, the optical axis angle of the POL film or RP film to be aligned can be determined based on the azimuth angle of the polarized light emitted from the optical module.

[0083] In one example, the optical module includes a alignment lens 21 and an alignment optical film 22, with the alignment optical film 22 positioned closer to the phase retardation element 3 than the alignment lens 21. The alignment optical film is a QWP film. Based on the intensity of the polarized light emitted from the polarizer 4 in multiple fields detected by the detection module 5, the azimuth and ellipsoid of the polarized light emitted from the optical module are calculated using the Stokes vector and Mueller matrix. The optical axis angle of the alignment optical film is then determined based on the azimuth and ellipsoid of the polarized light emitted from the optical module. Specifically, regardless of the type of polarized light emitted from the light source assembly, based on the principle that the QWP film can convert the polarization state of the beam, the polarized light emitted from the QWP film can be linearly polarized, circularly polarized, or elliptically polarized. When the polarized light emitted from the QWP film is linearly polarized, the vibration direction of the light vector of the linearly polarized light must be consistent with the fast or slow axis direction of the QWP film. When the polarized light emitted from the QWP film is elliptically polarized, its major and minor axes coincide with the fast and slow axes of the QWP film. The ellipticity of the elliptically polarized light can be calculated to determine the angle of the fast or slow axis of the QWP film. When the polarized light emitted from the QWP film is circularly polarized, the relative angle between the QWP's fast and slow axes and the lens is 45°. Therefore, the optical axis angle of the QWP film to be aligned can be determined based on the azimuth angle and ellipticity of the polarized light emitted from the optical module.

[0084] In step 4, the straight edge angle of the lens is obtained. The straight edge angle is the angle between the straight edge segment of the lens and the reference line, where the reference line is the vertical coordinate axis in the visual camera's 6-coordinate system.

[0085] In this step, the angle between the straight edge of the lens and the vertical coordinate axis determined by the visual camera 6 is obtained through the visual camera 6.

[0086] In one specific embodiment, a surface light source is provided to illuminate the side of the lens. A vision camera 6 captures an image of the straight edge of the lens, obtaining the angle between the straight edge segment of the lens and the vertical coordinate axis determined by the vision camera 6's own coordinates. The optical axis of the lens is actually a virtual axis, and its angle cannot be directly measured using any device. In this embodiment, a straight edge segment is provided on the lens to be aligned, and the optical axis angle of the lens to be aligned is indirectly characterized by detecting the angle of the straight edge segment.

[0087] The vision camera 6 is fixedly set, and the lens to be aligned is also fixedly set relative to the optical film to be aligned. Therefore, the straight edge angle of the lens to be aligned obtained by the vision camera 6 is a fixed value.

[0088] For example, after the lens to be aligned arrives at the manufacturer, it has a straight edge section. Specifically, the lens includes an arc-shaped portion and a straight edge section connected to the arc-shaped component. The straight edge section can be formed by cutting, for example, by cutting a circular lens to form a lens with a straight edge section.

[0089] In step 5, the optical film is rotated based on the optical axis angle of the optical film and the straight edge angle of the lens to align the optical module.

[0090] Specifically, based on the optical axis angle of the optical film 22 to be aligned and the straight edge angle of the lens 21 to be aligned, the optical film to be aligned can be rotated by an electric rotary wheel to compensate for the angle deviation, thereby completing the precise alignment of the polarization axis of the optical film and the lens in the optical module.

[0091] Therefore, in this embodiment, the optical axis angle of the optical film is determined by calculating the polarization parameters of the light emitted from the optical module, and the straight edge angle of the lens is obtained by the vision camera. By rotating the optical film, the optical axis angle of the optical film and the straight edge angle of the lens are aligned, thereby achieving precise alignment of the optical film and the lens in the optical module.

[0092] In an alternative embodiment, if only linearly polarized light is being measured, the phase retardation element rotating at angular frequency ω combined with the polarizer and CCD can be replaced by an expensive polarization camera. In an alternative embodiment, the CCD can be replaced by a CMOS sensor.

[0093] In one example, the phase delay element is a quarter-wave plate, and the polarizer is a horizontal linear polarizer.

[0094] In this embodiment, the types of phase delay element 3 and polarizer 4 are limited. The Mueller matrix of quarter-wave plate and horizontal linear polarizer is relatively simple, which can reduce the difficulty of obtaining the polarization parameters of the emitted light from the optical module.

[0095] In one example, the light source assembly includes a polarizer 14, and when the optical film is a phase retardation film, before controlling the polarized light of multiple fields of view to pass through the optical module to be aligned, the polarizer 4 is further configured to be at the ideal optical axis angle of the phase retardation film to be tested.

[0096] Specifically, the angle of the polarizer 14 is controlled to be the ideal optical axis angle of the phase retardation film under test. When the angle of the polarizer 14 coincides with the optical axis angle of the phase retardation film, the polarized light emitted from the phase retardation film is linearly polarized. When the angle of the polarizer and the optical axis angle of the phase retardation film are offset, the polarized light emitted from the phase retardation film is elliptically polarized or circularly polarized. Therefore, to ensure that the polarized light emitted from the phase retardation film is linearly polarized, the angle of the polarizer is controlled to be the ideal optical axis angle of the phase retardation film under test. When the detected optical axis angle of the phase retardation film coincides with the angle of the polarizer, the polarized light emitted from the phase retardation film is linearly polarized.

[0097] In one example, obtaining the polarization parameters of the light emitted from the optical module 2 to be aligned, based on the intensity of the light emitted from the polarizer 4 received by the detection module 5, specifically includes the following steps:

[0098] Step 01: Obtain the intensity of the light emitted from the polarizer 4 when the angle between the fast axis of the phase delay element 3 and the horizontal direction is α, where α = ωt, and t is the rotation time of the phase delay element;

[0099] Step 02: Based on the intensity of the light emitted from the polarizer 4, obtain the Stokes vector of the light emitted from the optical module 2 to be aligned;

[0100] Step 03: Obtain the polarization parameters of the emitted light from the optical module 2 to be aligned based on the Stokes vector of the emitted light.

[0101] In step 01, the intensity of the light emitted from the polarizer 4 is obtained when the angle between the fast axis of the phase delay element 3 and the horizontal direction is α, where α = ωt. Specifically, the polarized light from multiple fields of view emitted from the polarizer 4 is ultimately received by the detection module 5. After receiving the polarized light from multiple fields of view emitted from the polarizer 4, the intensity of the polarized light from multiple fields of view emitted from the polarizer 4 can be detected by the detection module 5. Since the phase delay element 3 is constantly rotating at an angular frequency ω, the detection module 5 can detect in real time the intensity of the polarized light from multiple fields of view emitted from the polarizer 4 when the angle between the fast axis of the phase delay element 3 and the horizontal direction is α.

[0102] In step 02, when the detection module 5 detects that the fast axis of the phase delay element 3 makes an angle α with the horizontal direction, and the intensity of the polarized light emitted from the polarizer 4 in multiple fields of view, the Stokes vector of the light emitted from the optical module can be obtained based on the intensity of the polarized light in the multiple fields of view emitted from the polarizer 4. The Stokes vector of the light emitted from the optical module characterizes the polarization state and intensity of the light beam.

[0103] For example, the Stokes vector for obtaining the emitted light from the optical module (i.e., the emitted light from the optical film in the optical module) is S. m .

[0104]

[0105] Where S0 represents the total light intensity, S1 represents the light intensity difference between horizontally and vertically linearly polarized light, S2 represents the light intensity difference between 45-degree and -45-degree linearly polarized light, and S3 represents the light intensity difference between right-handed and left-handed circularly polarized light.

[0106] S0, S1, S2, and S3 can all be represented by the intensity of polarized light from multiple fields of view emitted through polarizer 4.

[0107] In step 03, the Stokes vector S of the emitted light from the optical module is calculated. m This allows us to obtain the polarization parameters of the light emitted from the optical module.

[0108] For example, the polarization parameters of the light emitted from the optical module include the ellipticity of the light emitted from the optical module and the azimuth angle of the light emitted from the optical module.

[0109] For example, the azimuth angle ψ of the light emitted from the optical module can be obtained by formula (2);

[0110]

[0111] The ellipticity χ of the emitted light from the optical module can be obtained using formula (3):

[0112]

[0113] Therefore, in this embodiment, based on the intensity of the multiple field-of-view rays emitted by the polarizer 4 when the angle between the fast axis of the phase delay element 3 and the horizontal direction is α obtained by the detection module, the value of each element (S0, S1, S2 and S3) in formula (1) is calculated. Each element (S0, S1, S2 and S3) is also related to the angle between the fast axis of the phase delay element 3 and the horizontal direction. Then, based on the value of each element calculated in formula (1), the azimuth angle of the emitted light rays (polarized light of multiple field-of-view rays) of the optical module is calculated according to formula (2) and formula (3), respectively, and the azimuth angle of the emitted light rays of the optical module is calculated.

[0114] The optical module polarization parameter alignment method provided in this application embodiment uses a combination of a phase delay element 3 rotating at angular frequency ω, a polarizer 4, and a detection module 5 to detect the emitted light from the VR Pancake optical module.

[0115] When the optical film to be aligned 22 is a POL film or an RP film, the optical axis angle of the optical film to be aligned in the optical module is determined by calculating the azimuth angle of the emitted light from the optical module.

[0116] When the optical film to be aligned is a QWP film, the optical axis angle of the optical film to be aligned in the optical module is determined by calculating the azimuth angle and ellipticity of the emitted light from the optical module.

[0117] In one example, obtaining the Stokes vector of the light emitted from the optical module 2 to be aligned, based on the intensity of the light emitted from the polarizer 4, specifically includes the following steps:

[0118] Step 001: Obtain the relationship model between the intensity of the light emitted from the polarizer 4 and the Stokes vector of the light emitted from the optical module to be aligned;

[0119] Step 002: Perform a Fourier transform on the relationship model and obtain the Fourier transform coefficients based on the intensity of the light emitted from the polarizer 4;

[0120] Step 003: Obtain the Stokes vector of the emitted light from the optical module 2 to be aligned based on the Fourier transform coefficients.

[0121] In step S001, the intensity of the light emitted from the polarizer 4 is related to the Stokes vector of the light emitted from the optical module 2 to be aligned, and the rotation angle α of the phase delay element 3. For example, the rotation angle of the phase delay element 3 is the angle between the fast axis of the phase delay element 3 and the horizontal direction; the angle between the fast axis of the phase delay element 3 and the horizontal direction is α, where α = ωt.

[0122] For example, if phase delay element 3 is a quarter-wave plate and polarizer 4 is a horizontal linear polarizer, the relationship between the intensity of the light emitted from polarizer 4 and the Stokes vector of the light emitted from the optical module 2 to be aligned is expressed as follows:

[0123]

[0124] In formula (4), α is the angle between the fast axis of the phase delay element 3 and the horizontal direction, and S0, S1, S2 and S3 are all elements in the Stokes vector matrix of the emitted light rays of the optical module.

[0125] In step S002, a Fourier transform is performed on formula (4), and the Fourier transform coefficients are obtained based on the intensity of the light emitted from polarizer 4. Specifically, the relationship between the Fourier transform coefficients and the intensity of the detected light emitted from the polarizer can be obtained through the Fourier transform.

[0126] For example, formula (4) can be written in Fourier series form, where the Fourier series form corresponding to formula (4) is formula (5):

[0127]

[0128] Then, by applying a Fourier transform to formula (5), the relationship between the Fourier transform coefficients A, B, C, and D and the intensity of the detected polarizer 4 emitted light can be obtained. For example, formula (6) below shows the relationship between the Fourier transform coefficient A and the intensity of the detected polarizer emitted light; formula (7) shows the relationship between the Fourier transform coefficient B and the intensity of the detected polarizer emitted light; formula (8) shows the relationship between the Fourier transform coefficient C and the intensity of the detected polarizer emitted light; and formula (9) shows the relationship between the Fourier transform coefficient D and the intensity of the detected polarizer emitted light.

[0129]

[0130]

[0131]

[0132]

[0133] In step S003, the Stokes vector of the emitted light from the optical module is obtained based on the Fourier transform coefficients. Specifically, the parameters in the Stokes vector matrix of the emitted light from the optical module are obtained according to the above formulas (6)-(9).

[0134] Specifically, according to formulas (4) and (5), we can know that:

[0135]

[0136] B = S3 (11)

[0137]

[0138]

[0139] According to formulas (10) and (13), we can know that:

[0140] S0=AC (14)

[0141] S1=2C (15)

[0142] S2 = 2D (16)

[0143] S3=B (17)

[0144] Therefore, according to formulas (6)-(9) and (14)-(17), the parameters in the Stokes vector matrix of the outgoing light from the optical module can be obtained, and thus the Stokes vector of the outgoing light from the optical module can be obtained. Based on the obtained Stokes vector of the outgoing light from the optical module, combined with formulas (2)-(3), the azimuth angle and ellipticity of the outgoing light (polarized light from multiple fields of view) of the optical module can be calculated respectively.

[0145] In one example, obtaining the relationship model between the intensity of the light emitted from the polarizer 4 and the Stokes vector of the light emitted from the optical module 2 to be aligned specifically includes the following steps:

[0146] Step 0001: Set the Stokes vector of the emitted light from the optical module to Sm;

[0147] Step 0002: Obtain the Stokes vector S′ of the emitted light from the phase delay element 3 based on the Stokes vector Sm;

[0148] Step 0003: Obtain the Stokes vector Sout of the emitted light from the polarizer 4 based on the Stokes vector S′;

[0149] Step 0004: Based on the Stokes vector Sout, obtain the relationship model between the intensity of the light emitted from the polarizer 4 and the Stokes vector of the light emitted from the optical module 2 to be aligned.

[0150] Specifically, in step 0001, the Stokes vector of the light emitted from the optical module is first set to S. m Specifically, the Stokes vector of the light rays emitted from the optical film of the optical module is set to S. m .

[0151] For example, let the Stokes vector of the light rays emitted from the optical film in the optical module to be aligned be:

[0152]

[0153] Where S0 represents the total light intensity, S1 represents the light intensity difference between horizontally and vertically linearly polarized light; S2 represents the light intensity difference between 45-degree and -45-degree linearly polarized light; and S3 represents the light intensity difference between right-handed and left-handed circularly polarized light.

[0154] In step 0002, according to the Stokes vector S m To obtain the Stokes vector S′ of the emitted light from phase delay element 3, specifically, the Stokes vector of the emitted light from a certain element is the product of the Mueller matrix of that element and the Stokes vector of the emitted light from the previous element.

[0155] For example, according to the Stokes vector S m And the Mueller matrix of the phase delay element 3 with an angle α between the fast axis and the horizontal direction, to obtain the Stokes vector S′ of the light emitted from the phase delay element 3.

[0156] In a specific embodiment, the phase delay element 3 is a quarter-wave plate, and the Mueller matrix of the quarter-wave plate, which has an angle α between its fast axis and the horizontal direction, can be expressed as:

[0157]

[0158] The quarter-wave plate rotates at an angular velocity ω (α = ωt).

[0159] After the light emitted from the alignment optical module 2 passes through the rotating quarter-wave plate, the Stokes vector of the emitted light is:

[0160]

[0161] It should be noted that the phase delay element 3 can also be a half-wave plate. The half-wave plate allows the light emitted from the optical module to pass through it. After the light emitted from the optical module passes through the rotating half-wave plate, the Stokes vector of the emitted light is the product of the Mueller matrix of the half-wave plate and the Stokes vector of the light emitted from the optical module.

[0162] In step 0003, the Stokes vector S′ of the emitted light from polarizer 4 is obtained based on the Stokes vector S′. out Specifically, the Stokes vector of the light emitted from a certain component is the product of the Mueller matrix of that component and the Stokes vector of the light emitted from the previous component.

[0163] For example, based on the Stokes vector S′ and the Mueller matrix of polarizer 4, the Stokes vector S of the light emitted from polarizer 4 can be obtained. out .

[0164] In one specific embodiment, polarizer 4 is a horizontal linear polarizer. The Mueller matrix of the horizontal linear polarizer (i.e., the Mueller matrix of the transmission axis of the horizontal linear polarizer in the horizontal direction) is expressed as:

[0165]

[0166] The relationship between the light emitted through the horizontal linear polarizer and the light emitted from the optical module 2 to be aligned is as follows:

[0167] S out =NMS VR (twenty one)

[0168] The light emitted through a horizontal linear polarizer can be represented as follows, that is, the Stokes vector of the light emitted from the horizontal linear polarizer can be represented as follows:

[0169]

[0170] It should be noted that polarizer 4 can also be a circular polarizer. Based on the principle explained above, the Stokes vector of the light rays emitted after passing through the circular polarizer can be obtained.

[0171] In step 0004, according to the Stokes vector S out The relationship expression between the intensity of the light emitted from the polarizer 4 and the Stokes vector of the light emitted from the optical module 2 to be aligned is obtained.

[0172] Specifically, in the calculation, only the emitted light S out The first component, i.e., the total intensity, can be detected, S'0=I(α).

[0173]

[0174] Therefore, the above formula (4) shows the relationship between the intensity of the light emitted from polarizer 4 and the Stokes vector of the light emitted from the optical module 2 to be aligned. In formula (4), α is the angle between the fast axis of the phase delay element 3 and the horizontal direction, and S0, S1, S2, and S3 are all elements in the Stokes vector matrix of the light emitted from the optical module. Then, a Fourier transform is performed on formula (4), and the Fourier transform coefficients are obtained based on the intensity of the light emitted from polarizer 4. Specifically, through Fourier transform, the relationship between the Fourier transform coefficients and the intensity of the detected light emitted from the polarizer can be obtained. Then, through Fourier transform of the above formula (5), the relationship between the Fourier transform coefficients A, B, C, and D and the intensity of the detected light emitted from polarizer 4 can be obtained. For example, formula (6) above shows the relationship between the Fourier transform coefficient A and the intensity of the detected polarizer-emitted light, formula (7) shows the relationship between the Fourier transform coefficient B and the intensity of the detected polarizer-emitted light, formula (8) shows the relationship between the Fourier transform coefficient C and the intensity of the detected polarizer-emitted light, and formula (9) shows the relationship between the Fourier transform coefficient D and the intensity of the detected polarizer-emitted light.

[0175] Therefore, based on the above formulas (6)-(9) and (14)-(17), the parameters in the Stokes vector matrix of the emitted light from the optical module can be obtained, thus obtaining the Stokes vector of the emitted light from the optical module. Based on the obtained Stokes vector of the emitted light from the optical module, combined with the above formulas (2)-(3), the azimuth angle and ellipsoid of the emitted light (polarized light from multiple fields of view) of the optical module are calculated respectively. Finally, based on the obtained azimuth angle and ellipsoid of the emitted light from the optical module to be aligned, the optical axis angle of the optical film in the optical module is determined.

[0176] In one example, the phase delay element rotates at an angular frequency ω, specifically including:

[0177] The phase delay element is driven by a stepper motor to rotate at an angular frequency ω, where the number of steps of the stepper motor is n, the step size is aj, and α = ωt = n × aj.

[0178] In one specific embodiment, the phase delay element 3 is rotated by a stepper motor. For example, the quarter-wave plate is rotated by a stepper motor.

[0179] Specifically, a quarter-wave plate is placed on a fixed base and can be rotated in n steps by a stepper motor: ωt = nα j (α j (where α is the step size and N is the total number of steps). This is based on the formula α = ωt = nα. j By transforming formula (5), we can obtain formula (23).

[0180]

[0181] The Fourier transform can be used to obtain the relationship between the Fourier transform coefficients A, B, C and D and the intensity of the emitted light from the detected polarizer 4. Formulas (24)-(27) show the relationship between the Fourier transform coefficients A, B, C and D and the intensity of the emitted light from the detected polarizer 4.

[0182]

[0183]

[0184]

[0185]

[0186] Thus, in this embodiment, given the step size and number of steps of the stepper motor and the intensity of the emitted light from the polarizer 4, the Stokes vector of the emitted light from the optical module can be obtained. Then, the polarization parameters of the optical module are obtained based on the Stokes vector of the emitted light, and the optical axis angle of the optical film in the optical module is determined based on the polarization parameters of the optical module.

[0187] Secondly, embodiments of this application provide an optical module alignment system, the alignment system comprising:

[0188] The light source assembly 1, phase delay element 3, polarizer 4 and detection module 5 are provided. The phase delay element 3 rotates at an angular frequency ω. An optical module 2 to be aligned is placed between the light source assembly 1 and the phase delay element 3. The optical module 2 to be aligned includes an alignment lens and an alignment optical film. The alignment optical film 22 rotates relative to the alignment lens 21.

[0189] The light source assembly 1 is used to emit polarized light with multiple fields of view;

[0190] When the optical module 2 to be aligned is placed between the light source assembly 1 and the phase delay element 3, the optical module 2 to be aligned, the phase delay element 3, the polarizer 4 and the detection module 5 are arranged sequentially along the same optical axis, and the vision camera 6 is located above the lens 21 to be aligned.

[0191] In this embodiment, the light source assembly 1 emits polarized light with multiple fields of view. For example, the light source assembly 1 emits linearly polarized light with multiple fields of view, such that linearly polarized light with multiple fields of view is incident on the optical module to be aligned. The light emitted from the optical module passes through a phase delay element 3 rotating at an angular frequency ω and a polarizer 4, and is finally received by the detection module 5. This method allows the Stokes vector of the emitted light from the optical module to be aligned to be detected, thereby allowing the calculation of the ellipticity and azimuth angle of the optical module. Based on the calculated polarization parameters of the optical module, the optical axis angle of the optical film in the optical module to be aligned can be obtained. Furthermore, a vision camera can be fixed above the lens 21 to be aligned to obtain the straight edge angle of the lens 21.

[0192] In one example, the light source assembly includes: a light source, a fast reflector, a lens group, and a polarizer, wherein the lens group includes at least one lens;

[0193] The light emitted from the light source passes sequentially through the fast reflector, the lens group, and the polarizer before being projected onto the optical module under test.

[0194] Specifically, the lens group includes a first lens 12 and a second lens 13. The light emitted from the light source passes through a fast reflector 11, the first lens 12, and the second lens 13. F1 and F2 are the focal lengths of the first lens 12 and the second lens 13, respectively. After passing through a polarizer 14, it can generate linearly polarized light with multiple fields of view. The light source is a laser.

[0195] In one example, a stepper motor is also included, which drives the phase delay element to rotate at an angular frequency ω.

[0196] In this embodiment, the phase delay element 3 is driven by a stepper motor. Given the step size and number of steps of the stepper motor, and the intensity of the emitted light from the polarizer 4, the Stokes vector of the emitted light from the optical module can be obtained. Then, the polarization parameters of the emitted light are obtained based on the Stokes vector, and the optical axis angle of the optical film in the optical module is obtained based on these polarization parameters.

[0197] In one example, the polarizer is a horizontal linear polarizer, and the phase delay element is a quarter-wave plate.

[0198] In this embodiment, the types of phase delay element 3 and polarizer 4 are limited. The Mueller matrix of quarter-wave plate and horizontal linear polarizer is relatively simple, which can reduce the difficulty of obtaining the Stokes vector of the light emitted from the optical module.

[0199] The specific implementation of the optical film alignment system in this application can refer to the various embodiments of the optical module alignment method described above. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0200] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0201] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. An optical module alignment method, characterized in that, An optical module alignment method is applied to an optical module alignment system, which includes a light source assembly, a phase retardation element, a polarizer, and a detection module. The phase retardation element rotates at an angular frequency ω, and the light source assembly and the phase retardation element are positioned between the light source assembly and the phase retardation element to align an optical module. The optical module to be aligned includes a lens to be aligned and an optical film to be aligned, and the optical film to be aligned is rotatable relative to the lens to be aligned. When the optical module to be aligned is positioned between the light source assembly and the phase retardation element, the alignment system further includes a vision camera. The optical module alignment method includes: Polarized light controlling multiple fields of view is sequentially projected onto the detection module through the optical module to be aligned, the phase delay element, and the polarizer; Based on the intensity of the polarizer-emitted light received by the detection module, the polarization parameters of the light emitted by the optical module to be aligned are obtained. The optical axis angle of the optical film to be aligned is determined based on the polarization parameters. Obtain the straight edge angle of the lens to be aligned, wherein the straight edge angle is the angle between the straight edge of the lens and the reference line, and the reference line is the vertical coordinate axis in the visual camera coordinate system; The optical film to be aligned is rotated based on the polarization parameters and the straight edge angle to achieve the alignment of the optical module.

2. The alignment method according to claim 1, characterized in that, The optical film is one of a polarizing film, a reflective polarizing film, or a phase delay film.

3. The alignment method according to claim 2, characterized in that, When the optical film to be aligned is a phase retardation film, the polarization parameters of the light emitted from the polarizer received by the detection module are obtained as azimuth angle and ellipticity.

4. The alignment method according to claim 2, characterized in that, When the optical film to be aligned is a polarizing film or a reflective polarizing film, the polarization parameter of the light emitted from the polarizer received by the detection module is obtained as the azimuth angle.

5. The alignment method according to claim 1, characterized in that, The phase delay element is a quarter-wave plate, and the polarizer is a horizontal linear polarizer.

6. The alignment method according to claim 1, characterized in that, The light source assembly includes a polarizer, and when the optical film to be aligned is a phase retardation film, it further includes the following before the polarized light controlling multiple fields of view passes through the optical module to be aligned: The angle of the polarizer is controlled to be the ideal optical axis angle of the phase retardation film under test.

7. The alignment method according to claim 1, characterized in that, Obtaining the polarization parameters of the light emitted from the polarizer based on the intensity of the light received by the detection module specifically includes: The intensity of the light emitted from the polarizer is obtained when the angle between the fast axis of the phase delay element and the horizontal direction is α, where α = ωt, and t is the rotation time of the phase delay element; Based on the intensity of the light emitted from the polarizer, the Stokes vector of the light emitted from the optical module to be aligned is obtained; The polarization parameters of the emitted light from the optical module to be aligned are obtained based on the Stokes vector of the emitted light from the optical film to be aligned.

8. The alignment method according to claim 7, characterized in that, Obtaining the Stokes vector of the light emitted from the polarizer based on its intensity specifically includes: A model is established to determine the relationship between the intensity of the light emitted from the polarizer and the Stokes vector of the light emitted from the optical module to be aligned. Perform a Fourier transform on the relationship model and obtain the Fourier transform coefficients based on the intensity of the light emitted from the polarizer; Based on the Fourier transform coefficients, the Stokes vector of the emitted light from the optical module to be aligned is obtained.

9. The alignment method according to claim 8, characterized in that, The model for obtaining the relationship between the intensity of the light emitted from the polarizer and the Stokes vector of the light emitted from the optical film to be aligned specifically includes: The Stokes vector of the light emitted from the optical module to be aligned is set as Sm; Based on the Stokes vector Sm, obtain the Stokes vector of the emitted light from the phase delay element. ; According to the Stokes vector Obtain the Stokes vector Sout of the light emitted from the polarizer; Based on the Stokes vector Sout, a relationship model is obtained between the intensity of the light emitted from the polarizer and the Stokes vector of the light emitted from the optical module to be aligned.

10. The alignment method according to claim 9, characterized in that, According to the Stokes vector S m Obtain the Stokes vector of the emitted light from the phase delay element. Specifically, it includes: According to the Stokes vector S m And the Mueller matrix of the phase retardation element with an angle α between the fast axis and the horizontal direction, to obtain the Stokes vector of the emitted light from the phase retardation element. .

11. The alignment method according to claim 9, characterized in that, According to the Stokes vector Obtaining the Stokes vector Sout of the polarizer-emitted light specifically includes: According to the Stokes vector And the Mueller matrix of the polarizer, to obtain the Stokes vector Sout of the polarizer's outgoing light.

12. The alignment method according to claim 1, characterized in that, The phase delay element rotates at an angular frequency ω, specifically including: The phase delay element is driven by a stepper motor to rotate at an angular frequency ω, where the number of steps of the stepper motor is n, the step size is aj, and α=ωt=n×aj.

13. An optical module alignment system, characterized in that, The optical module alignment system performs the optical module alignment method as described in any one of claims 1-12; The alignment system includes: The light source assembly, phase delay element, polarizer and detection module, wherein the phase delay element rotates at an angular frequency ω; between the light source assembly and the phase delay element is a space for placing an optical module to be aligned, the optical module to be aligned including an alignment lens and an alignment optical film, the alignment optical film rotating relative to the alignment lens. The light source assembly is used to emit polarized light with multiple fields of view; When the optical module to be aligned is placed between the light source assembly and the phase delay element, the optical module to be aligned, the phase delay element, the polarizer and the detection module are arranged sequentially along the same optical axis, and the vision camera is located above the lens to be aligned.

14. The alignment system according to claim 13, characterized in that, The light source assembly includes: a light source, a fast reflector, a lens group, and a polarizer, wherein the lens group includes at least one lens; The light emitted from the light source passes sequentially through the fast reflector, the lens group, and the polarizer before being projected onto the optical module under test.

15. The alignment system according to claim 13, characterized in that, It also includes a stepper motor that drives the phase delay element to rotate at an angular frequency ω.

16. The alignment system according to claim 13, characterized in that, The polarizer is a horizontal linear polarizer, and the phase delay element is a quarter-wave plate.

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