Lens polarization alignment assembling device and method based on optical power monitoring

Abstract

The invention provides a lens polarization alignment assembly device based on optical power monitoring, which is used for displaying an optical machine module, and belongs to the technical field of near-to-eye display. The device comprises a light source module, an adjusting module, an optical power meter and an ultraviolet curing device which are arranged along a first optical axis; the display light machine module comprises a first lens group and a second lens group which are arranged along a second optical axis. According to the device, the specific optical power of the laser after the polarization state change in the display optical machine module is detected by the optical power meter, and the angle alignment relationship between the lens groups is converted into the reading change of the optical power meter. Compared with an original method that the first lens group and the second lens group are directly assembled in a mechanical registration mode, the method can introduce high-precision angle compensation in the assembling and adjusting process, the precision deviation generated in the part machining and assembling process is made up, the polarization angle can be controlled more accurately in the auxiliary assembling and adjusting process, and the precision of the lens is improved. And the occurrence of stray light and secondary images is inhibited.

Description

Technical Field

[0001] This invention belongs to the field of near-eye display technology, specifically relating to a lens polarization alignment assembly device and assembly method based on optical power monitoring. Background Technology

[0002] As the concept of the metaverse moves from science fiction to industrial application, near-eye display (NED) devices have become a recognized core entry point for next-generation human-computer interaction. The Pancake optical solution, with its lightweight design and wide field of view, has become a mainstream solution in current near-eye display optical systems. In the Pancake optical solution, light is folded by the polarization functional film layer, greatly compressing the total optical length and delivering a wide field of view immersive experience. However, the Pancake optical system has a significant drawback—ghosting. Ghosting refers to the "image" formed at a certain location in the image by stray light (caused by multiple reflections at the lens interface, scattering due to lens defects, scattering due to physical structures, etc.) in an optical imaging system. In the Pancake system, the generation of ghosting is highly correlated with the polarization angle alignment. Currently, polarization angle alignment heavily relies on the bonding accuracy during the polarization film lamination process and is also affected by the structural positioning accuracy. This method is difficult to align, has a low yield, and lacks feedback verification during final assembly. If the polarization alignment accuracy is not well controlled during assembly, it will result in severe ghosting, excessive light leakage, and a degraded display effect.

[0003] Therefore, in order to solve the problem that the polarization angle accuracy error between lenses cannot be accurately adjusted and the display ghosting is heavy in the existing assembly method, it is necessary to provide an assembly method that can calibrate the polarization angle error during lens assembly, thereby suppressing ghosting, light leakage and other problems of the module. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that the polarization angle accuracy error between lenses cannot be accurately adjusted in existing assembly methods, resulting in heavy ghosting. This invention provides an assembly method that can calibrate the polarization angle error during lens assembly, thereby suppressing ghosting and light leakage problems in the module.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a lens polarization alignment assembly device based on optical power monitoring for displaying an optical engine module. The device includes a light source module, an adjustment module, an optical power meter, and an ultraviolet curing device arranged along a first optical axis. The display optical engine module includes a first lens group and a second lens group arranged along a second optical axis.

[0006] The lens polarization alignment assembly device based on optical power monitoring provided by this invention also has the following technical feature: the light source module includes a laser, a circular polarizer, and a reflector within the display wavelength range. The laser wavelength is in the range of 510-560nm, the spot diameter is no more than 1mm, and the polarization direction is random polarization; the circular polarizer is composed of a linear polarizer and a quarter-wave plate at a 45° angle, with one side of the linear polarizer placed close to the laser perpendicular to the optical path.

[0007] The lens polarization alignment assembly device based on optical power monitoring provided by the present invention also has the following technical features: the first lens group is a single lens or a lens group including multiple lenses and a housing; the second lens group is a single lens or a lens group including multiple lenses and a housing.

[0008] The lens polarization alignment assembly device based on optical power monitoring provided by the present invention also has the following technical features: a quarter-wave plate is attached to the lens in the first lens group, and the angle between the fast axis direction and the reference direction is 135°±0.5°; a semi-reflective and semi-transparent film is coated on the lens in the first lens group, and the surface has 50% reflection and 50% transmission of light, with no polarization selectivity. The lens in the second lens group is fitted with a reflective polarizer, and the angle between the transmission axis angle of the reflective polarizer and the reference angle is 90°±0.5°.

[0009] Another object of the present invention is to provide a lens polarization alignment assembly method based on optical power monitoring, the assembly method being implemented using the assembly apparatus as described in any of the preceding claims, comprising: S1, the optical engine module will be installed in the adjustment module; S2, pre-apply adhesive around the periphery of the first lens group; S3, Align the light source module with the optical power meter; S4, adjust the angle of the first lens group according to the test value of the optical power meter until the angle is aligned; S5, use an ultraviolet curing device to expose and cure the periphery of the first lens group to complete the lens polarization direction alignment and assembly.

[0010] The lens polarization alignment assembly method based on optical power monitoring provided by the present invention also has the following technical feature: the adjustment module is used to adjust the rotation angle of the first lens group and fix the posture of the second lens group separately.

[0011] The lens polarization alignment assembly method based on optical power monitoring provided by the present invention also has the following technical feature: S1 further includes ensuring that the first lens group is rotated and adjusted ±5° about the second optical axis when installing the first lens group.

[0012] The lens polarization alignment assembly method based on optical power monitoring provided by the present invention also has the following technical feature: S2 includes uniformly applying adhesive in the gap between the first lens group and the second lens group, with the amount of adhesive being 1 / 2 to 3 / 4 of the gap volume.

[0013] The lens polarization alignment assembly method based on optical power monitoring provided by the present invention also has the following technical feature: in step S3, the alignment of the light source module and the optical power meter is such that the optical power meter receiving window receives the light spot formed by the light emitted by the light source module after passing through the display optomechanical module.

[0014] The lens polarization alignment assembly method based on optical power monitoring provided by the present invention also has the following technical features: S4 includes: while adjusting the angle of the first lens group, observing the change in the optical power meter reading, and when the reading reaches the peak and valley values, determining that the angle alignment position has been reached.

[0015] Beneficial effects: The lens polarization alignment assembly device based on optical power monitoring provided by this invention uses an optical power meter to detect the specific optical power after the laser undergoes a polarization state change in the display optomechanical module, converting the angular alignment relationship between lens groups into the reading of the optical power meter. Specifically, based on lens polarization alignment assembly using the optical power meter reading as the basis for assembly and adjustment, compared to the original method of directly assembling the first and second lens groups together using mechanical structures, this method can introduce angle compensation during the assembly and adjustment process. This compensates for the accuracy deviations caused by film application and component installation, enabling more precise control of the polarization angle during the auxiliary assembly and adjustment process and suppressing the occurrence of stray light and secondary images. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention. Figure 2 This is a structural schematic diagram of Embodiment 2 of the present invention. Figure 3 This is a diagram of the lens polarization alignment assembly method based on optical power monitoring according to the present invention. Figure 4 This is a schematic diagram of the optical path of the display optical engine module in operation according to the present invention. Figure 5 This is a simulation diagram of the light spot received by the detection surface of the optical power meter of this invention. Figure 6This is a schematic diagram of the process in Example 2 where the industrial control computer uses an algorithm to control the adjustment module to automatically align the angle and position of the first lens group. Figure 7 This is a graph showing the result of the algorithm fitting the optical power value I with the rotation angle value θ. in, 1: Light source module; 11: Laser; 12: Circular polarizer; 13: Mirror; 2: Adjustment module; 3: Optical power meter; 4: Ultraviolet curing device; 5: Display optomechanical module; 51: First lens group; 52: Second lens group; 6: Industrial control computer. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent changes or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the protection scope of the present invention.

[0019] In the description of the embodiments of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention.

[0020] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0021] The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of these terms in this invention based on the specific circumstances.

[0022] Example 1: like Figure 1As shown, a lens polarization alignment assembly device based on optical power monitoring includes the following parts: a light source module 1, an adjustment module 2, an optical power meter 3, and an ultraviolet curing device 4. The light source module 1 includes a laser 11, a circular polarizer 12, and a reflector 13, all within the display wavelength range. The laser 11 generates collimated light, and the circular polarizer 12 converts the light generated by the laser into circularly polarized light. The laser 11 is a 543nm gas laser with a spot diameter of 0.83mm and random polarization. The circular polarizer 12 is composed of a linear polarizer and a quarter-wave plate at a 45° angle, with one side of the linear polarizer positioned close to the laser beam perpendicular to the optical path. The reflector 13 is positioned at a 45° angle to deflect the ground-parallel laser beam downwards, facilitating observation and operation.

[0023] The adjustment module 2 serves to fix and adjust the lens group. The display module has a rotationally symmetrical structure. The adjustment module fixes the second lens group in the reference direction using fastening screws. When the first lens group is installed in the adjustment module, it has a pre-positioned structure, with the positioning reference surface on the second lens group as the reference surface, so that the initial adjustment position of the first and second lens groups is the theoretical design position. The first and second lens groups are constrained by mechanical structure to ensure that the optical axes of the two lens groups are coaxial. The clamping mechanism can rotate the first lens group within a range of ±5° around the second optical axis.

[0024] The optical power meter 3 is capable of monitoring the optical power intensity of the emitted light spot. The accuracy of the optical power meter 3 should be no less than 0.5%; the measurement uncertainty of the optical power meter 3 should be no less than 1.5%; preferably, the minimum measured power of the optical power meter 3 should be no greater than 1 nW; the measurement spectral range of the optical power meter 3 should at least cover 400 nm-700 nm. In this embodiment, the accuracy of the optical power meter 3 is 0.25%; the measurement uncertainty of the optical power meter 3 is 1.1%; the minimum measured power of the optical power meter 3 is 20 pW; and the measurement spectral range of the optical power meter 3 can cover 400 nm-1100 nm.

[0025] The ultraviolet curing device 4 is used to cure the UV adhesive after the lens angle is aligned. The wavelength of the ultraviolet curing device 4 is 365nm and the maximum light power density is 80mW / cm².

[0026] The display optical engine module is the object to be adjusted, including a first lens group and a second lens group arranged along the second optical axis. The first lens group is a convex lens; the second lens group is a lens group assembled with two lenses and a housing; a quarter-wave plate is pre-attached to the first lens group, with the fast axis direction and the reference direction having an angle of 135°±0.5°; a semi-reflective and semi-transparent film is pre-coated on the first lens group, with the surface reflecting 50% of light and transmitting 50%, and having no polarization selectivity; a reflective polarizer is pre-attached to the second lens group, with the reflective polarizer's transmission axis angle and the reference angle having an angle of 90°±0.5°.

[0027] A lens polarization alignment and assembly method based on optical power monitoring, using the above-mentioned lens alignment and assembly device, includes the following steps: S1, the optical engine module 5 is installed in the adjustment module 2, and the adjustment module 2 can adjust the rotation angle of the first lens group 51 independently; S2, pre-apply adhesive to the first lens group 51 circumference; S3, Align the light source module 1 with the optical power meter 3; S4, adjust the angle of the first lens group according to the test value of the optical power meter 3 until the angle is aligned; S5, the first lens group 51 is exposed and cured by UV curing device 4 to complete the alignment and assembly of the lens polarization direction.

[0028] In step S2, adhesive is applied between the first lens group and the second lens group. The amount of adhesive should be 1 / 2 to 3 / 4 times the volume of the gap, and it should be evenly applied to the perimeter of the gap. In step S3, the alignment of the light source module and the optical power meter should be based on the following: the receiving window of the optical power meter should be able to receive the light spot formed after the light emitted by the light source module passes through the display optomechanical module. like Figure 4 As shown, multiple light spots may appear on the detection surface of the optical power meter. When the first optical axis of the adjustment device coincides with the second optical axis of the display module, the light spots formed by different optical paths will overlap, making it impossible to measure the power of the light spot emitted from a single optical path individually. Therefore, it is necessary to shift the adjustment module so that the first optical axis of the adjustment device is 3mm away from the second optical axis of the display module. At this time, the light spot distribution is as follows. Figure 5 As shown, a single direct-transmittance spot is extracted using an optical power meter. When the spot power reaches its minimum value, the polarization direction alignment condition is met.

[0029] Example 2: like Figure 2 As shown, a lens polarization alignment assembly device based on optical power monitoring includes the following components: a light source module 1, an adjustment module 2, an optical power meter 3, an ultraviolet curing device 4, and an industrial control computer 6. The assembly and adjustment device in Example 2 is based on Example 1, but differs from Example 1 in that: The adjustment module consists of a fixing mechanism, a clamping mechanism, a servo motor, an encoder disk, and a controller.

[0030] The fixing mechanism is used to fix the posture of the first lens group, ensuring that the posture of the first lens group remains stable during the adjustment of the second lens group. The clamping mechanism is driven by a servo motor, and the second lens group and the first lens group rotate coaxially. The encoder disk is used for position detection and feedback, indirectly ensuring that the clamping mechanism is adjusted according to precise position and speed; The controller controls the servo motor to move according to the instructions input from the industrial computer; The industrial computer 6 is responsible for running the control algorithm and sending motion commands to the adjustment module controller; The assembly and adjustment method in Example 2 is based on Example 1, but differs from Example 1 in that: like Figure 3 , Figure 6 As shown, step S4 is achieved by the industrial control computer using an algorithm to automatically align the angle of the first lens group. Specifically: S41, the servo motor controls the clamping mechanism to rotate within a range of -5° to 5° according to a certain step size; S42, the optical power meter and encoder disk send the optical power value I and rotation angle value θ of each point to the industrial control computer; S43, the industrial control computer uses an algorithm to fit the relationship between a set of optical power values ​​and the rotation angle of the first lens group, and gives the minimum optical power value I. min The corresponding rotation angle θ1; S44, the industrial control computer sends the motion command of rotating θ1 to the adjustment module controller, controlling the first lens group to rotate to the correct angle.

[0031] The industrial control computer receives the optical power meter test results at various times and the rotation angle of the first lens group at that time, forming a set of correspondences between the optical power value and the rotation angle of the first lens group. The algorithm uses the following formula for fitting:

[0032] in, The detected optical power value, For power coefficient, This is the deflection angle of the first lens group. This is the initial angle of the first lens group. To illustrate the effect of ambient light on optical power, the fitting results during implementation are shown below. Figure 7 .

[0033] The angular accuracy of the assembly and alignment was further optimized by algorithm fitting, avoiding the problem of inaccurate power extreme value position testing due to single-point test errors. The automated assembly and alignment of the device improved the efficiency and consistency of the assembly and alignment, and realized the polarization angle compensation alignment between lens groups, making up for the angular errors introduced during the part film application and assembly process.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A lens polarization alignment assembly device based on optical power monitoring for a display optical engine, characterized in that, The device comprises a light source module, an adjusting module, a light power meter and an ultraviolet curing device arranged along a first optical axis, and the display light machine module comprises a first lens group and a second lens group arranged along a second optical axis.

2. The lens polarization alignment assembly based on optical power monitoring of claim 1, wherein, The light source module comprises a laser in a display waveband range, a circular polarizer and a mirror, The wavelength of the laser is in the range of 510-560 nm, the spot diameter is not greater than 1 mm, and the polarization direction is random polarization; the circular polarizer is composed of a linear polarizer and a quarter-wave plate at an angle of 45°, and the linear polarizer is placed on one side of the laser perpendicular to the optical path.

3. The lens polarization alignment assembly based on optical power monitoring of claim 1, wherein, The first lens group is a single lens or a lens group comprising a plurality of lenses and a housing; and the second lens group is a single lens or a lens group comprising a plurality of lenses and a housing.

4. The lens polarization alignment assembly based on optical power monitoring of claim 3, wherein, A quarter-wave plate is attached to the lens in the first lens group, and the angle between the fast axis direction and the reference direction is 135°±0.5°; a semi-reflective and semi-transmissive film is coated on the lens in the first lens group, and the surface reflects 50% of the light and transmits 50% of the light without polarization selectivity. A reflective polarizer is attached to the lens in the second lens group, and the angle between the transmission axis angle of the reflective polarizer and the reference angle is 90°±0.5°.

5. A method of lens polarization alignment assembly based on optical power monitoring, characterized in that, The assembly method is implemented using the assembly device according to any one of claims 1-4, comprising: S1, installing the display light machine module in the adjusting module; S2, pre-gluing around the first lens group; S3, aligning the light source module with the light power meter; S4, adjusting the angle of the first lens group according to the test value of the light power meter until the angle alignment position is reached; S5, exposing and curing the first lens group around the lens using the ultraviolet curing device to complete the polarization direction alignment and assembly of the lens.

6. The lens polarization alignment assembly method based on optical power monitoring according to claim 5, wherein, The adjusting module is used to individually adjust the rotation angle of the first lens group and fix the posture of the second lens group.

7. The lens polarization alignment assembly method based on optical power monitoring according to claim 5, wherein, S1 further comprises ensuring that the first lens group is rotated and adjusted by ±5° around the second optical axis when installing the first lens group.

8. The lens polarization alignment assembly method based on optical power monitoring according to claim 5, wherein, S2 comprises uniformly applying glue in the gap between the first lens group and the second lens group, and the amount of glue is 1 / 2-3 / 4 of the volume of the gap.

9. The lens polarization alignment assembly method based on optical power monitoring according to claim 5, wherein, In S3, the light source module is aligned with the light power meter, that is, the light spot formed after the light emitted by the light source module passes through the display light machine module is received by the receiving window of the light power meter.

10. The lens polarization alignment assembly method based on optical power monitoring according to claim 5, wherein, S4 comprises observing the change of the light power meter while adjusting the angle of the first lens group, and when the peak and valley values of the number are reached, it is determined that the angle alignment position is reached.

Images