Optical alignment method and optical alignment device
By adjusting the distance between the workpieces in the optical alignment method, the ghost disappears, and the problem of optical alignment in the prior art is solved, the accuracy of alignment is improved and fitting abnormalities are avoided.
Patent Information
- Application Number
- CN202211127286.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-16
- Publication Date
- 2025-06-03
- Estimated Expiration
- 2042-09-16
AI Technical Summary
In the existing optical alignment method, the intensity of the emitted light after the laser passes through the two polarizing elements cannot accurately reflect the alignment of the polarizing axis, resulting in abnormal bonding.
By obtaining the outgoing beam image of the laser passing through the first workpiece and the second workpiece, it is determined whether there is a ghost. If it exists, adjust the distance between the workpieces to make the ghost disappear. If it does not exist, detect the intensity of the light spot to be detected to determine the successful alignment.
It effectively avoids the impact of ghosting on the success of the counterpoint, improves the accuracy of the counterpoint, and avoids fitting abnormalities.
Smart Images
Figure CN115480353B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of optical alignment, and more particularly, to an optical alignment method and an optical alignment device. Background Art
[0002] A polarizing element can allow light of a specific polarization direction to pass through or change the polarization state of light. When two polarizing elements are bonded together, it is necessary to first align the two polarizing elements so that their polarization axes form a preset angle. Usually, the alignment of the two polarizing elements is determined by detecting the intensity of the light emitted after the laser passes through the two polarizing elements in sequence.
[0003] However, in the existing optical alignment methods, the light emitted after the laser passes through the two polarizing elements in sequence includes not only the primary penetration light that forms the spot to be detected, but also the multiple reflected lights that form ghost images. Therefore, the intensity of the emitted light in the existing optical alignment methods cannot truly reflect the accuracy of the alignment of the polarization axes of the two polarizing elements, resulting in abnormal bonding of the two polarizing elements. Summary of the Invention
[0004] The first aspect of this application provides an optical alignment method. The optical alignment method includes:
[0005] Spacially arranging a first workpiece and a second workpiece, where the first workpiece includes a first polarizing element and the second workpiece includes a second polarizing element;
[0006] Obtaining an image of the emitted light beam after the laser passes through the first workpiece and the second workpiece in sequence; and
[0007] Judging whether there is a ghost image overlapping with the spot to be detected in the image of the emitted light beam. If there is a ghost image in the image of the emitted light beam, adjust the distance between the first workpiece and the second workpiece to make the ghost image disappear in the image of the emitted light beam. If there is no ghost image in the image of the emitted light beam, detect the intensity of the spot to be detected to judge whether the first workpiece and the second workpiece are successfully aligned.
[0008] By adjusting the distance between the first workpiece and the second workpiece to make the ghost image disappear in the image of the emitted light beam, this optical alignment method can avoid the influence of the ghost image on the successful alignment of the first workpiece and the second workpiece, improve the alignment accuracy of the first workpiece and the second workpiece, and avoid abnormal bonding of the first workpiece and the second workpiece.
[0009] The second aspect of this application provides an optical alignment device. The optical alignment device includes:
[0010] A light source for emitting a laser;
[0011] The first jig is used to fix the first workpiece, and the first workpiece includes a first polarizing element;
[0012] The second jig is used to fix the second workpiece, and the second workpiece includes a second polarizing element. The laser passes through the first workpiece and the second workpiece in sequence to obtain an outgoing light beam;
[0013] The optical sensor is used to acquire an image of the outgoing light beam and detect the intensity of a spot to be detected in the image of the outgoing light beam, so as to determine whether the first workpiece and the second workpiece are successfully aligned; and
[0014] The adjustment platform is used to adjust the distance between the first workpiece and the second workpiece when there is a ghost image overlapping with the spot to be detected in the image of the outgoing light beam, so that the ghost image disappears in the image of the outgoing light beam.
[0015] In this optical alignment device, when there is a ghost image overlapping with the spot to be detected in the image of the outgoing light beam, the adjustment platform can adjust the distance between the first workpiece and the second workpiece, so that the ghost image disappears in the image of the outgoing light beam. This can avoid the influence of the ghost image on whether the first workpiece and the second workpiece are successfully aligned, improve the alignment accuracy of the first workpiece and the second workpiece, and avoid abnormal fitting of the first workpiece and the second workpiece. Brief Description of the Drawings
[0016] Figure 1 It is a schematic flowchart of an optical alignment method according to an embodiment of the present application.
[0017] Figure 2A and Figure 2B They are respectively a schematic optical path diagram of the first workpiece and the second workpiece at a specific distance and a schematic diagram of the image of the outgoing light beam.
[0018] Figure 3 It is a schematic diagram of the incident angle, incident height and outgoing angle of the light ray.
[0019] Figures 4A to 4G They are respectively a schematic optical path diagram of the first workpiece and the second workpiece at different distances and a schematic diagram of the image of the outgoing light beam.
[0020] Main Element Symbol Description:
[0021] Optical alignment device 100
[0022] Light source 110
[0023] Focusing lens 120
[0024] Optical detector 130
[0025] First workpiece 210
[0026] The first polarizing element 211
[0027] The lens 212
[0028] The partially transmissive and partially reflective element 213
[0029] The second workpiece 220
[0030] The second polarizing element 222
[0031] The optical axis X
[0032] The first surface S1
[0033] The second surface S2
[0034] The preset angle α
[0035] The spot P1 to be detected
[0036] The ghost images G1, G2
[0037] The primary transmitted light L1
[0038] The primary refracted and reflected light L2
[0039] The secondary refracted and reflected light L3
[0040] The distance D
[0041] The following specific embodiments will further illustrate the present application in conjunction with the above-mentioned drawings. Specific embodiments
[0042] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.
[0043] Figure 1 It is a schematic flowchart of an optical alignment method according to an embodiment of the present application. As Figure 1 shown, the optical alignment method includes the following steps S1 to S5.
[0044] Step S1: Dispose the first workpiece and the second workpiece at intervals.
[0045] Step S2: Obtain an image of the emerging light beam after the laser passes through the first workpiece and the second workpiece in sequence.
[0046] Step S3: Determine whether there is a ghost image overlapping with the spot to be detected in the image of the emerging light beam. If there is a ghost image in the image of the emerging light beam, execute Step S4; otherwise, execute Step S5.
[0047] Step S4: Adjust the distance between the first workpiece and the second workpiece so that the ghost image disappears in the image of the outgoing beam.
[0048] Step S5: Detect the intensity of the spot to be detected to determine whether the first workpiece and the second workpiece are successfully aligned.
[0049] The following is combined with Figures 2A to 4G Specifically described below.
[0050] Specifically, in step S1, the first workpiece 210 and the second workpiece 220 are placed in the optical alignment device 100.
[0051] As Figure 2A shown, the first workpiece 210 includes a first polarizing element 211, a lens 212, and a partially transmissive and partially reflective element 213. The lens 212 includes opposite first surface S1 and second surface S2. The first surface S1 is a concave surface, and the second surface S2 is a convex surface. The first polarizing element 211 is disposed on the first surface S1. The partially transmissive and partially reflective element 213 is disposed on the second surface S2. The second workpiece 220 includes a second polarizing element 222. The first polarizing element 211 is located between the first surface S1 and the second polarizing element 222, and there is an air gap between the first polarizing element 211 and the second polarizing element 222. This optical alignment method is used to align the polarization axes of the first polarizing element 211 and the second polarizing element 222. In other embodiments, the first surface S1 is a convex surface and the second surface S2 is a concave surface.
[0052] In some embodiments, the partially transmissive and partially reflective element 213 is a semi-transmissive and semi-reflective film coated on the second surface S2 of the lens 212. The first polarizing element 211 is a phase retardation plate (e.g., a quarter-wave plate) attached to the first surface S1 of the lens 212. The second polarizing element 222 is a reflective polarizing element. In other embodiments, the second workpiece 220 may include another lens, and the second polarizing element 222 is disposed on the surface of the other lens facing the lens 212.
[0053] The optical alignment device 100 includes a light source 110, a first jig (not shown in the figure), a second jig (not shown in the figure), a focusing lens 120, and an optical detector 130 that are sequentially arranged at intervals. The first jig is used to fix the first workpiece 210, and the second jig is used to fix the second workpiece 220. Along the direction from the light source 110 to the optical detector 130, they are the light source 110, the first jig, the partially transmissive and partially reflective element 213, the lens 212, the first polarizing element 211, the second polarizing element 222, the second jig, the focusing lens 120, and the optical detector 130 in sequence.
[0054] The light source 110 is a laser light source for emitting laser light. Both the first jig and the second jig are provided with light-transmitting holes. In some embodiments, the laser light emitted by the light source 110 is collimated parallel light.
[0055] In step S2, the laser light emitted by the light source 110 passes through the light-transmitting hole of the first jig to the first workpiece 210 and then enters the second workpiece 220, and then forms an outgoing light beam after passing through the second workpiece 220. The outgoing light beam exits from the light-transmitting hole of the second jig to the focusing lens 120, and then is converged by the focusing lens 120 to the optical detector 130. The optical detector 130 can acquire an image of the outgoing light beam and is used to detect the intensity of the outgoing light beam to determine whether the first workpiece 210 and the second workpiece 220 are successfully aligned. As Figure 2A shown, the first workpiece 210 and the second workpiece 220 have a common optical axis X. The laser light emitted by the light source 110 forms a preset angle α with the optical axis X.
[0056] In some embodiments, the preset angle α is greater than or equal to 0 degrees and less than or equal to 10 degrees (such as 4 degrees, 6 degrees, 8 degrees). By making the outgoing light beam of the laser inclined relative to the optical axis X, the partial return light between the first polarizing element 211 and the second polarizing element 222 can be deviated from the sensing range of the optical detector 130, reducing the interference of ghost images or stray light.
[0057] It should be noted that although the outgoing light beam of the laser being inclined relative to the optical axis X can make the partial return light deviate from the sensing range of the optical detector 130, however, due to the difference in the bending shape of the lens 212 and the setting of the partially transmitting and partially reflecting element 213, there is refracted and reflected light between the first polarizing element 211 and the second polarizing element 222, resulting in multiple refracted and reflected lights in the outgoing light rays after the laser passes through the first workpiece 210 and the second workpiece 220, causing the problem of ghost images. And the optical alignment method of the embodiment of the present application can make the ghost image disappear in the image of the outgoing light beam by adjusting the distance D between the first workpiece 210 and the second workpiece 220, further reducing the interference of ghost images.
[0058] Specifically, as Figure 2A shown, the outgoing light beam after the laser light emitted by the light source 110 passes through the first workpiece 210 and the second workpiece 220 includes a primary transmitted light L1, a primary refracted and reflected light L2, and a secondary refracted and reflected light L3.
[0059] The optical path of the primary transmitted light L1 is as follows: The laser light emitted by the light source 110 sequentially passes through the partially transmitting and partially reflecting element 213, the lens 212, the first polarizing element 211, and the second polarizing element 222 to form the primary transmitted light L1. The primary transmitted light L1 is converged by the focusing lens 120 onto the optical detector 130 and constitutes the main image or the spot to be detected P1 (shown in Figure 2B ).
[0060] The optical path of the primary catadioptric light L2 is as follows: The laser emitted by the light source 110 passes through the partially transmissive and partially reflective element 213, the lens 212, and the first polarizing element 211 of the first workpiece 210 and then enters the second polarizing element 222. Then, it is reflected back to the first workpiece 210 by the second polarizing element 222 again, and then reflected back to the second polarizing element 222 by the partially transmissive and partially reflective element 213 of the first workpiece 210 again. Then, it penetrates the second polarizing element 222, is focused by the focusing lens 120 onto the optical detector 130, and forms a ghost image G1 in the image of the outgoing light beam (shown in Figure 2B .
[0061] The optical path of the secondary catadioptric light L3 is as follows: The laser emitted by the light source 110 passes through the partially transmissive and partially reflective element 213, the lens 212, and the first polarizing element 211 of the first workpiece 210 and then enters the second polarizing element 222. Then, it is reflected back to the first workpiece 210 by the second polarizing element 222 again, and then reflected back to the second polarizing element 222 by the partially transmissive and partially reflective element 213 of the first workpiece 210 again. Then, it is reflected back to the first workpiece 210 by the second polarizing element 222 again, and then reflected back to the second polarizing element 222 by the partially transmissive and partially reflective element 213 of the first workpiece 210 again. Then, it penetrates the second polarizing element 222, is focused by the focusing lens 120 onto the optical detector 130, and forms a ghost image G2 in the image of the outgoing light beam (shown in Figure 2B .
[0062] As Figure 3 shown, according to the geometric paraxial ray equation, the calculation of the outgoing light angle u' of the ray is determined by the following three factors: the incident height y of the ray, the refractive index n of the incident ray, and the incident angle u of the ray. Since the laser emitted by the light source 110 undergoes multiple catadioptric reflections between the partially transmissive and partially reflective element 213 of the first workpiece 210 and the second polarizing element 222, and the incident height y and angle u of the primary transmitted light L1 and the catadioptric light (especially the secondary catadioptric light L3) are close when they enter the second polarizing element 222 in the optical path, the outgoing angles u' of the two from the second polarizing element 222 are similar, which in turn causes the main image formed by the primary transmitted light L1 and the ghost images G1, G2, etc. formed by the reflected light to be unable to be effectively separated.
[0063] In this optical alignment method, if in step S3, it is determined that there is a ghost image G1 overlapping with the spot P1 to be detected in the image of the outgoing light beam, then step S4 is executed to adjust the distance D between the first workpiece 210 and the second workpiece 220. By adjusting the distance D between the partially transmissive and partially reflective element 213 and the second polarizing element 222, the differences in the height y and the angle u of the primary transmitted light L1 and the refracted and reflected light (especially the secondary refracted and reflected light L3) when they are incident on the second polarizing element 222 in the optical path are increased, so that the ghost images G1, G2, etc. deviate from the detection range of the optical detector 130, separating the ghost images G1, G2, etc. from the spot P1 to be detected and disappearing from the image of the outgoing light beam.
[0064] Specifically, Figures 4A to 4G They are respectively the optical path diagrams when the preset angle α is 4 degrees and the distance D between the partially transmissive and partially reflective element 213 and the second polarizing element 222 in the first workpiece 210 is 23 mm, 22 mm, 21 mm, 20 mm, 19 mm, 18 mm, and 17 mm. Figures 4A to 4G The right diagrams in are respectively the images of the outgoing light beam obtained by the optical detector 130 corresponding to the left diagrams. From Figures 4A to 4G it can be seen that as the distance D between the partially transmissive and partially reflective element 213 and the second polarizing element 222 in the first workpiece 210 gradually increases from 17 mm, the ghost images G1, G2 gradually separate from the spot P1 to be detected (or the main image). When the distance D between the partially transmissive and partially reflective element 213 and the second polarizing element 222 in the first workpiece 210 is 22 mm and 23 mm, the ghost images G1 and G2 have been completely separated and disappeared from the image of the outgoing light beam.
[0065] It can be understood that the outgoing light beam does not only include the primary refracted and reflected light L2 and the secondary refracted and reflected light L3, but may also include the tertiary refracted and reflected light, the quaternary refracted and reflected light, etc. Among them, the tertiary refracted and reflected light, the quaternary refracted and reflected light, etc. are either ignored due to too weak light intensity or can also be separated from the main image by adjusting the distance between the first workpiece 210 and the second workpiece 220 so that they deviate from the sensing range of the optical detector 130.
[0066] In some embodiments, the optical alignment device 100 includes an adjustment platform (not shown in the figure). The adjustment platform can cause relative displacement between the first fixture and the second fixture, and thus can adjust the distance D between the first workpiece 210 and the second workpiece 220 when there is a ghost image overlapping with the spot P1 to be detected in the image of the outgoing light beam sensed by the optical detector 130, so that the ghost image disappears from the image of the outgoing light beam.
[0067] Specifically, the adjustment platform includes, for example, a driving unit that can drive the first fixture to move towards the second fixture or away from the second fixture. Understandably, the adjustment platform can also drive the second fixture to move towards or away from the first fixture to adjust the distance between the first workpiece 210 and the second workpiece 220.
[0068] In addition, if it is determined in step S3 that there is no ghost image overlapping with the to-be-detected light spot P1 in the image of the outgoing light beam, then step S5 is executed to detect the intensity of the to-be-detected light spot P1 to determine whether the first workpiece 210 and the second workpiece 220 are successfully aligned.
[0069] Understandably, when the polarization axes of the first polarizing element 211 and the second polarizing element 222 do not reach a specific included angle, the intensity of the outgoing light beam is relatively large after the laser emitted by the light source 110 passes through the first workpiece 210 and the second workpiece 220; while when the polarization axes of the first polarizing element 211 and the second polarizing element 222 reach a specific included angle, the intensity of the outgoing light beam is the smallest after the laser emitted by the light source 110 passes through the first workpiece 210 and the second workpiece 220.
[0070] In some embodiments, if the optical detector 130 detects that the intensity of the outgoing light beam reaches a preset value, it indicates that the first polarizing element 211 and the second polarizing element 222 are successfully aligned; otherwise, the included angle between the first polarizing element 211 and the second polarizing element 222 is adjusted until the first polarizing element 211 and the second polarizing element 222 are successfully aligned.
[0071] In some embodiments, the step of adjusting the included angle between the first polarizing element 211 and the second polarizing element 222 is realized, for example, by an adjustment platform. The adjustment platform further includes a rotation driving unit, which is, for example, a motor and can drive the first fixture to rotate relative to the second fixture, thereby adjusting the included angle between the first polarizing element 211 and the second polarizing element 222. Understandably, in some embodiments, the rotation driving unit can also drive the second fixture to rotate relative to the first fixture to adjust the included angle between the first polarizing element 211 and the second polarizing element 222.
[0072] In some embodiments, after it is confirmed in step S5 that the first workpiece 210 and the second workpiece 220 are successfully aligned, the optical alignment method further includes a step of bonding the first workpiece 210 and the second workpiece 220. For example, a bonding adhesive (not shown in the figure) has been provided on the surface of the first workpiece 210 facing the second workpiece 220 or the surface of the second workpiece 220 facing the first workpiece 210 before alignment. After the first workpiece 210 and the second workpiece 220 are successfully aligned, the first workpiece 210 and the second workpiece 220 are brought closer and bonded by the bonding adhesive.
[0073] In summary, for the optical alignment method and the optical alignment device according to the embodiments of the present application, by adjusting the distance between the first workpiece and the second workpiece, the ghost image disappears in the image of the outgoing light beam, which can avoid the influence of the ghost image on whether the first workpiece and the second workpiece are successfully aligned, improve the alignment accuracy of the first workpiece and the second workpiece, and avoid abnormal bonding of the first workpiece and the second workpiece. The above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.
Claims
1. An optical alignment method, characterized in that, it includes: The first workpiece and the second workpiece are arranged at intervals, wherein the first workpiece includes a first polarizing element, and the second workpiece includes a second polarizing element; Obtain an image of the outgoing light beam after the laser passes through the first workpiece and the second workpiece in sequence; and Judge whether there is a ghost overlapping with the spot to be detected in the image of the outgoing light beam. If there is a ghost in the image of the outgoing light beam, adjust the distance between the first workpiece and the second workpiece so that the ghost disappears in the image of the outgoing light beam; if there is no ghost in the image of the outgoing light beam, detect the intensity of the spot to be detected to judge whether the first workpiece and the second workpiece are successfully aligned; The first workpiece and the second workpiece have a common optical axis, and the laser forms a preset angle with the optical axis; The preset angle is greater than or equal to 0 degrees and less than or equal to 10 degrees.
2. The optical alignment method according to claim 1, characterized in that, The first workpiece further includes a lens and a partially transmissive and partially reflective element; the lens includes opposite first and second surfaces, the first polarizing element is arranged on the first surface, and the partially transmissive and partially reflective element is arranged on the second surface.
3. The optical alignment method according to claim 2, characterized in that, The first polarizing element is a phase retardation plate, and the second polarizing element is a reflective polarizing element.
4. The optical alignment method according to claim 3, characterized in that, In the step of adjusting the distance between the first workpiece and the second workpiece, the distance between the partially transmissive and partially reflective element and the reflective polarizing element is adjusted.
5. The optical alignment method according to claim 2, characterized in that, The first surface is a concave surface, and the second surface is a convex surface; or, the first surface is a convex surface, and the second surface is a concave surface.
6. The optical alignment method according to claim 1, characterized in that, Use an optical detector to obtain an image of the outgoing light beam; in the step of adjusting the distance between the first workpiece and the second workpiece, make the ghost deviate from the detection range of the optical detector so that the ghost disappears in the image of the outgoing light beam.
7. The optical alignment method according to claim 6, characterized in that, After the first workpiece and the second workpiece are successfully aligned, the first workpiece and the second workpiece are bonded together.
8. An optical alignment device, characterized in that, it includes: A light source for emitting a laser; A first jig for fixing a first workpiece, the first workpiece including a first polarizing element; A second jig for fixing a second workpiece, the second workpiece including a second polarizing element, and the laser passes through the first workpiece and the second workpiece in sequence to obtain an outgoing light beam; An optical sensor for obtaining an image of the outgoing light beam and for detecting the intensity of the spot to be detected in the image of the outgoing light beam to judge whether the first workpiece and the second workpiece are successfully aligned; and Adjustment platform, which is used to adjust the distance between the first workpiece and the second workpiece when there is a ghost image overlapping with the spot to be detected in the image of the outgoing beam, so that the ghost image disappears in the image of the outgoing beam.
Citation Information
Patent Citations
Projector
CN101075080A
Method and apparatus for aligning two optical subsystems
US20200174383A1