Optical module and manufacturing method therefor, and near-to-eye display device

Abstract

An optical module and a manufacturing method therefor, and a near-to-eye display device. The optical module has a light incident side (S1) and a light exit side (S2), and comprises a first lens (100), a partial reflector (110), a phase retarder (120), a second lens (130), a reflective polarizer (140), and a light-transmitting structure (150). The partial reflector (110) is arranged on the side of the first lens (100) close to the light incident side (S1), the phase retarder (120) is arranged on the side of the first lens (130) distant from the partial reflector (110), the second lens (130) is arranged on the side of the phase retarder (120) distant from the first lens (100), the reflective polarizer (140) is arranged on the side of the second lens (130) close to the phase retarder (120), and the light-transmitting structure (150) is arranged on the side of the reflective polarizer (140) close to the phase retarder (120). The reflective polarizer (140) has a reflection axis direction and a transmission axis direction which are perpendicular to each other, the light-transmitting structure (150) has a minimum refractive direction, the light-transmitting structure (150) has a minimum refractive index in the minimum refractive direction for linearly polarized light parallel to the minimum refractive direction, and the included angle between the minimum refractive direction and the reflection axis direction is greater than or equal to 70 degrees and less than or equal to 90 degrees, so that the reflective polarizer (140) has a greater reflective polarization ratio.

Description

Optical module, manufacturing method thereof, and near-eye display device

[0001] This application claims priority to Chinese Patent Application No. 202311020645.7 filed on August 14, 2023. The contents of the above-mentioned Chinese patent application disclosure are hereby incorporated by reference in their entirety as a part of this application. Technical Field

[0002] Embodiments of the present disclosure relate to an optical module, a method for manufacturing the same, and a near-eye display device. Background Art

[0003] In virtual reality (VR) devices, near-eye displays (NEDs) use lenses to magnify the image on the display, creating an immersive experience. Currently, the main lens technologies used are Fresnel lenses and Pancake (ultra-short-throw folded optical path) lenses. Pancake lenses significantly reduce the required distance between the NED and the human eye by folding the optical path, making VR devices lighter and thinner.

[0004] Summary of the Invention

[0005] The key component of a pancake lens that enables both reflection and transmission of light is the reflective polarizing film. The optical module provided by the disclosed embodiments reduces the reflectivity of polarized light perpendicular to the reflection axis while minimizing the effect on the reflectivity of polarized light parallel to the reflection axis, thereby enabling the reflective polarizer to achieve a greater reflection polarization ratio.

[0006] Embodiments of the present disclosure provide an optical module, a method for manufacturing the same, and a near-eye display device.

[0007] At least one embodiment of the present disclosure provides an optical module having a light incident side and a light exiting side, comprising: a first lens; a partial reflector, arranged on a side of the first lens close to the light incident side; a phase retarder, arranged on a side of the first lens away from the partial reflector, configured to convert circularly polarized light into linearly polarized light, or to convert linearly polarized light into circularly polarized light; a second lens, arranged on a side of the phase retarder away from the first lens; a reflective polarizer, arranged on a side of the second lens close to the phase retarder; and a light-transmitting structure, arranged on a side of the reflective polarizer close to the phase retarder, and spaced apart from the phase retarder, wherein the partial reflector is configured to transmit light incident from the light incident side. The reflective polarizer is configured to reflect light incident from the phase retarder and change the polarization state of the light, wherein the reflective polarizer has a reflection axis direction and a transmission axis direction perpendicular to each other, and the reflective polarizer reflects linearly polarized light parallel to the reflection axis direction in the reflection axis direction and keeps the polarization state of the linear polarized light unchanged, and transmits linearly polarized light parallel to the transmission axis direction in the transmission axis direction and keeps the polarization state of the linear polarized light unchanged, the light-transmitting structure has a lowest refractive direction, and the refractive index of the light-transmitting structure for linearly polarized light parallel to the lowest refractive direction is the lowest in the lowest refractive direction, and the angle between the lowest refractive direction and the reflection axis direction is greater than or equal to 70 degrees and less than or equal to 90 degrees.

[0008] At least one embodiment of the present disclosure provides a method for manufacturing an optical module, wherein the optical module has a light incident side and a light emitting side, and the manufacturing method comprises: providing a first lens; providing a partial reflector on a side of the first lens close to the light incident side; providing a phase retarder on a side of the first lens away from the partial reflector, wherein the phase retarder is configured to convert circularly polarized light into linearly polarized light or to convert linearly polarized light into circularly polarized light; providing a second lens on a side of the phase retarder away from the first lens; providing a reflective polarizer on a side of the second lens close to the phase retarder; providing a light-transmitting structure on a side of the reflective polarizer close to the phase retarder, wherein a gap is set between the light-transmitting structure and the phase retarder, and the partial reflector is configured to To transmit light incident from the light incident side and to reflect light incident from the phase retarder and change the polarization state of the light, the reflective polarizer has a reflection axis direction and a transmission axis direction perpendicular to each other, the reflective polarizer reflects linearly polarized light parallel to the reflection axis direction in the reflection axis direction and maintains the polarization state of the linear polarized light unchanged, the reflective polarizer transmits linearly polarized light parallel to the transmission axis direction in the transmission axis direction and maintains the polarization state of the linear polarized light unchanged, the light-transmitting structure has a lowest refractive direction, the refractive index of the light-transmitting structure for linearly polarized light parallel to the lowest refractive direction is lowest in the lowest refractive direction, and the angle between the lowest refractive direction and the reflection axis direction is greater than or equal to 70 degrees and less than or equal to 90 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, rather than limiting the present disclosure.

[0010] FIG1 is a schematic structural diagram of a Pancake (ultra-short focus folded optical path) lens;

[0011] FIG2 is a measured reflectivity of a reflective polarizing film;

[0012] FIG3 shows the measured reflectivity of another reflective polarizing film;

[0013] FIG4 is a schematic structural diagram of an optical module provided in one embodiment of the present disclosure;

[0014] FIG5 is a schematic diagram of the light path of the optical module shown in FIG4 ;

[0015] FIG6 is a partial top view of a stacked structure of a reflective polarizer and a light-transmitting structure provided by one embodiment of the present disclosure;

[0016] FIG7 is a partial cross-sectional schematic diagram of the laminate structure shown in FIG6 ;

[0017] FIG8 is a partial top view of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure;

[0018] FIG9 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure;

[0019] FIG10 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure;

[0020] FIG11 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure;

[0021] FIG12 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure;

[0022] FIG13 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure;

[0023] FIG14 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure;

[0024] FIG15 is a schematic diagram of a partial structure of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure;

[0025] FIG16 is a data comparison diagram of the reflective polarization selectivity ratio of a reflective polarizer and a light-transmitting structure provided by one embodiment of the present disclosure;

[0026] FIG17 is a schematic structural diagram of a near-eye display device provided by an embodiment of the present disclosure;

[0027] FIG18 is a flow chart of a method for manufacturing an optical module according to an embodiment of the present disclosure;

[0028] FIG19 is a flow chart of a manufacturing method for forming a light-transmitting structure on one side of a reflective polarizer according to an embodiment of the present disclosure; and

[0029] FIG20 is a schematic diagram of another manufacturing method for forming a light-transmitting structure on one side of a reflective polarizer provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0031] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0032] Unless otherwise defined, the features such as "parallel", "perpendicular" and "same" used in the embodiments of the present disclosure include the cases of "parallel", "perpendicular", "same" in a strict sense, as well as the cases of "approximately parallel", "approximately perpendicular", "approximately the same" and the like which contain certain errors. For example, the above-mentioned "approximately" may mean that the difference between the compared objects is 10% of the average value of the compared objects, or within 5%. When the number of a component or element is not specifically indicated below in the embodiments of the present disclosure, it means that the component or element may be one or more, or may be understood as at least one. "At least one" refers to one or more, and "multiple" refers to at least two. The "same-layer arrangement" in the embodiments of the present disclosure refers to the relationship between multiple film layers formed by the same material after the same step (for example, a one-step patterning process). The "same layer" here does not always mean that the thickness of multiple film layers is the same or the height of multiple film layers in the cross-sectional view is the same.

[0033] Figure 1 is a schematic diagram of the structure of a Pancake (ultra-short-throw folded optical path) lens. As shown in Figure 1, the surface of screen 01 is equipped with a wave plate, which emits right-handed circularly polarized light 1. After passing through transflective coating 02, the polarization state of the light remains unchanged, remaining right-handed circularly polarized light 2. After passing through phase retarder film 03, the right-handed circularly polarized light 3 becomes linearly polarized light 3. The polarization direction of linearly polarized light 3 is parallel to the reflection axis of reflective polarizing film 04. Consequently, linearly polarized light 3 is reflected by reflective polarizing film 04 as linearly polarized light 4. It then passes through phase retarder film 03 again and becomes right-handed circularly polarized light 5. After being reflected by transflective coating 02, the right-handed circularly polarized light 5 becomes left-handed circularly polarized light 6 due to half-wave loss. Left-handed circularly polarized light 6 passes through phase retarder film 03 and becomes linearly polarized light 7, whose polarization direction is parallel to the transmission axis of reflective polarizing film 04. It then passes through reflective polarizing film 04 as light 8 and enters the human eye. The Pancake lens folds the optical path along this path, reducing the space required for the lens assembly.

[0034] The reflective polarizing film 04 has a reflection axis and a projection axis that are perpendicular to each other. The polarized light component whose polarization direction is parallel to the reflection axis has an extremely high reflectivity on the reflective polarizing film 04, while the transmittance is extremely low; the polarized light component whose polarization direction is perpendicular to the reflection axis (i.e., parallel to the transmission axis) has an extremely low reflectivity on the reflective polarizing film, while the transmittance is extremely high.

[0035] Therefore, the key component that enables the Pancake lens to achieve reflection and transmission of the above-mentioned optical path is the reflective polarizing film 04. An ideal reflective polarizing film completely reflects polarized light parallel to its reflection axis, while having zero reflectivity for polarized light perpendicular to its reflection axis. However, actual reflective polarizing films still reflect some polarized light perpendicular to the reflection axis. In a Pancake lens, polarized light parallel to the reflection axis reflected by the reflective polarizing film is used for imaging, while polarized light perpendicular to the reflection axis is unnecessary. This light, which does not participate in imaging, mixes into the folded optical path, causing stray light and ghosting, which affect the visual experience. Therefore, minimizing the reflectivity of polarized light perpendicular to the reflection axis on the surface of the reflective polarizing film, and making the reflective polarizing film closer to the ideal, is an important factor in improving the visual experience of a Pancake lens.

[0036] The most important characteristic of a reflective polarizing film is its polarization selectivity, or R / / , the ratio of its reflectivity for light polarized parallel to its reflection axis (R / / ) to its reflectivity for light polarized perpendicular to its reflection axis (R⊥). R / / / R⊥ is the ideal polarization selectivity. In a pancake lens, polarized light reflected parallel to its reflection axis is the "signal" used for imaging, while polarized light reflected perpendicular to its reflection axis is unwanted "noise." Therefore, the R / / / R⊥ can be considered the film's "signal-to-noise ratio."

[0037] The reflective polarization characteristics of the reflective polarizing film require a special material structure to be realized. There are currently two technical routes: 1. By stacking many layers of birefringent films stretched in different orientations, polarized light in different directions interferes between the films to achieve reflective polarization; 2. Preparing metal gratings on plastic film materials by nanoimprinting to achieve reflective polarization. Both of these technical routes cannot achieve an extremely high reflective polarization selectivity. For example, a typical reflective polarizing film may have a reflectivity of 80%, 90% or 98% for polarized light with a polarization direction parallel to its reflection axis (R / / ), while the reflectivity of polarized light with a polarization direction perpendicular to its reflection axis (R⊥) may be 20%, 10% or 8%.

[0038] Figure 2 shows the measured reflectivity of one reflective polarizing film; Figure 3 shows the measured reflectivity of another reflective polarizing film. Figure 2 shows the reflectivity of the reflective polarizing film achieved using Technical Route 1, while Figure 3 shows the reflectivity of the reflective polarizing film achieved using Technical Route 2. As shown in Figures 2 and 3, both reflective polarizing films still have a reflectivity exceeding 10% for light polarized perpendicular to the reflection axis. Calculated based on the average values, the reflective polarization selectivity of the reflective polarizing film shown in Figure 2 is 9.30, while that of the reflective polarizing film shown in Figure 3 is 6.66.

[0039] One current solution to this problem is to form an anti-reflection layer on the surface of the reflective polarizing film, such as by coating it with an anti-reflection coating. However, anti-reflection coatings do not have polarization selectivity. While they can reduce the reflectivity of polarized light perpendicular to the reflection axis, they also reduce the reflectivity of polarized light parallel to the reflection axis. While overall, anti-reflection coatings can indeed improve the reflective polarization selectivity, the reduction in reflectivity along the reflection axis may affect the optical efficiency of the lens and also limit further improvements in the reflective polarization selectivity.

[0040] In this regard, an embodiment of the present disclosure provides an optical module and a method for manufacturing an optical module. The optical module has a light incident side and a light exit side, and the optical module includes a first lens, a partial reflector, a phase retarder, a second lens, a reflective polarizer and a light-transmitting structure. The partial reflector is arranged on a side of the first lens close to the light incident side, and the phase retarder is arranged on a side of the first lens away from the partial reflector, and is configured to convert circularly polarized light into linearly polarized light, or to convert linearly polarized light into circularly polarized light. The second lens is arranged on a side of the phase retarder away from the first lens, the reflective polarizer is arranged on a side of the second lens close to the phase retarder, and the light-transmitting structure is arranged on a side of the reflective polarizer close to the phase retarder, and is spaced apart from the phase retarder. The partial reflector is configured to transmit light incident from the light incident side, and is configured to reflect light incident from the phase retarder and change the polarization state of the light. The reflective polarizer has a reflection axis direction and a transmission axis direction that are perpendicular to each other. The reflective polarizer reflects linearly polarized light parallel to the reflection axis direction in the reflection axis direction and keeps the polarization state of the linearly polarized light unchanged. The reflective polarizer transmits linearly polarized light parallel to the transmission axis direction in the transmission axis direction and keeps the polarization state of the linearly polarized light unchanged. The light-transmitting structure has a lowest refractive direction. The refractive index of the light-transmitting structure for linearly polarized light parallel to the lowest refractive direction is the lowest in the lowest refractive direction. The angle between the lowest refractive direction and the reflection axis direction is greater than or equal to 70 degrees and less than or equal to 90 degrees.

[0041] In the optical module provided by the embodiment of the present disclosure, it is assumed that the light incident from the light incident side is right-handed circularly polarized light. After passing through the partial reflector, the polarization state of the light remains unchanged. After passing through the phase retarder, it becomes light of the first linear polarization state. When the polarization direction of the light in the first linear polarization state is parallel to the reflection axis direction of the reflective polarizer, the light is reflected by the reflective polarizer as light of the first linear polarization state, and after passing through the phase retarder again, it becomes light of the right-handed circularly polarized state. After the right-handed circularly polarized light is reflected by the partial reflector, due to the half-wave loss, it becomes light of the left-handed circularly polarized state. After passing through the phase retarder, the left-handed circularly polarized light becomes light of the second linear polarization state. The polarization direction of the light in the second linear polarization state is parallel to the transmission axis direction of the reflective polarizer, thereby passing through the reflective polarizer to become light and enter the light output side of the optical module.

[0042] In the optical module provided in the embodiment of the present disclosure, a light-transmitting structure is provided on the side of the reflective polarizer close to the phase retarder, and the light-transmitting structure has a lowest refraction direction. The refractive index of the light-transmitting structure for polarized light parallel to the lowest refraction direction in the lowest refraction direction is the lowest, and the angle between the lowest refraction direction of the light-transmitting structure and the reflection axis direction of the reflective polarizer is greater than or equal to 70 degrees and less than or equal to 90 degrees. Therefore, for polarized light with a polarization direction perpendicular to the reflection axis direction, since the light-transmitting structure has the lowest refraction direction, the reflection of polarized light with a polarization direction perpendicular to the reflection axis direction can be reduced, the reflection polarization ratio of the reflective polarizing film can be improved, and the polarization light with a polarization direction perpendicular to the reflection axis direction can be reduced from entering the folded light path, thereby avoiding the occurrence of phenomena such as stray light and ghosting that affect the visual experience, and improving the clarity, contrast and visual experience of the near-eye display device where the optical module is located.

[0043] Compared to the isotropic anti-reflection films in the prior art, since the isotropic anti-reflection films have no polarization selectivity, while reducing the reflectivity of polarized light perpendicular to the reflection axis, they also reduce the reflectivity of polarized light parallel to the reflection axis. The light-transmitting structure provided in the embodiment of the present disclosure has a minimum refractive direction. The light-transmitting structure is anisotropic and has different refractive indices in the directions perpendicular to the reflection axis and parallel to the reflection axis. The angle between the minimum refractive direction of the light-transmitting structure and the reflection axis direction of the reflective polarizer is greater than or equal to 70 degrees and less than or equal to 90 degrees. Thus, while reducing the reflectivity of polarized light perpendicular to the reflection axis, the influence of the light-transmitting structure on the reflectivity of polarized light parallel to the reflection axis can be minimized, thereby enabling the reflective polarizer to have a larger reflection polarization ratio and avoiding the light-transmitting structure from adversely affecting the optical efficiency of the optical module.

[0044] The optical module and the method for manufacturing the optical module provided by the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0045] An embodiment of the present disclosure provides an optical module. FIG4 is a schematic diagram of an optical module provided in an embodiment of the present disclosure, and FIG5 is a schematic diagram of the optical path of the optical module shown in FIG4 . As shown in FIG4 , the optical module has a light incident side S1 and a light exit side S2, and the optical module includes a first lens 100, a partial reflector 110, a phase retarder 120, a second lens 130, a reflective polarizer 140, and a light-transmitting structure 150. The partial reflector 110 is arranged on a side of the first lens 100 close to the light incident side S1, and the phase retarder 120 is arranged on a side of the first lens 100 away from the partial reflector 110, and is configured to convert circularly polarized light into linearly polarized light, or convert linearly polarized light into circularly polarized light. The second lens 130 is disposed on a side of the phase retarder 120 away from the first lens 100. The reflective polarizer 140 is disposed on a side of the second lens 130 close to the phase retarder 120. The light-transmitting structure 150 is disposed on a side of the reflective polarizer 140 close to the phase retarder 120 and is spaced apart from the phase retarder 120. The partial reflector 110 is configured to transmit light incident from the light incident side S1 and to reflect light incident from the phase retarder 120 and change the polarization state of the light. The reflective polarizer 140 has a reflection axis direction and a transmission axis direction that are perpendicular to each other. The reflective polarizer 140 reflects linearly polarized light parallel to the reflection axis direction in the reflection axis direction and maintains the polarization state of the linearly polarized light unchanged. The reflective polarizer 140 transmits linearly polarized light parallel to the transmission axis direction in the transmission axis direction and maintains the polarization state of the linearly polarized light unchanged. The transparent structure 150 has a lowest refractive direction. The refractive index of the transparent structure 150 for linearly polarized light parallel to the lowest refractive direction is the lowest in the lowest refractive direction. The angle between the lowest refractive direction and the reflection axis direction is greater than or equal to 70 degrees and less than or equal to 90 degrees.

[0046] As shown in FIG4 and FIG5, in order to more clearly illustrate the change in the polarization state of light, it is assumed that the light incident from the light incident side is a right-handed circularly polarized light 10 (the right-handed circularly polarized state is used for schematic illustration, but is not a limitation of the embodiments of the present disclosure). After passing through the partial reflector 110, the polarization state of the light 20 remains unchanged. After passing through the phase retarder 120, the right-handed circularly polarized light 20 becomes a first linearly polarized light 30. When the polarization direction of the light 30 in the first linearly polarized state is parallel to the reflection axis direction of the reflective polarizer 140, the light 30 is reflected by the reflective polarizer 140. The light 40 is incident as a first linear polarization state, and after passing through the phase retarder 120 again, it becomes a right-handed circularly polarized light 50. After being reflected by the partial reflector 110, the right-handed circularly polarized light 50 becomes a left-handed circularly polarized light 60 due to half-wave loss. The left-handed circularly polarized light 60 becomes a second linear polarization state after passing through the phase retarder 120. The polarization direction of the second linear polarization state light 70 is parallel to the transmission axis direction of the reflective polarizer 140, and thus passes through the reflective polarizer 140 to become light 80 and enter the light output side of the optical module.

[0047] In the optical module provided by the embodiment of the present disclosure, a light-transmitting structure 150 is provided on the side of the reflective polarizer 140 close to the phase retarder 120. The light-transmitting structure 150 has a lowest refractive direction. The refractive index of the light-transmitting structure 150 for polarized light parallel to the lowest refractive direction in the lowest refractive direction is the lowest, and the angle between the lowest refractive direction of the light-transmitting structure 150 and the reflection axis direction of the reflective polarizer 140 is greater than or equal to 70 degrees and less than or equal to 90 degrees. Therefore, for polarized light with a polarization direction perpendicular to the reflection axis direction, since the light-transmitting structure 150 has the lowest refractive direction, the reflection of polarized light with a polarization direction perpendicular to the reflection axis direction can be reduced, the reflection polarization ratio of the reflective polarizing film can be improved, and the polarization light with a polarization direction perpendicular to the reflection axis direction can be reduced from entering the folded light path, thereby avoiding the occurrence of phenomena such as stray light and ghosting that affect the visual experience, and improving the clarity, contrast and visual experience of the near-eye display device where the optical module is located.

[0048] Compared to the isotropic anti-reflection films in the prior art, which have no polarization selectivity, the light-transmitting structure 150 provided in the present disclosure has a minimum refractive index direction. The light-transmitting structure 150 is anisotropic and has different refractive indices in the directions perpendicular to and parallel to the reflection axis. The angle between the minimum refractive index direction of the light-transmitting structure 150 and the reflection axis direction of the reflective polarizer 140 is greater than or equal to 70 degrees and less than or equal to 90 degrees. Thus, while reducing the reflectivity of polarized light perpendicular to the reflection axis, the light-transmitting structure 150 can also minimize the effect of the light-transmitting structure 150 on the reflectivity of polarized light parallel to the reflection axis, thereby enabling the reflective polarizer 140 to have a larger reflection polarization ratio and preventing the light-transmitting structure 150 from adversely affecting the optical efficiency of the optical module.

[0049] It should be noted that the reflective polarizer 140 and the phase retarder 120 are aligned, and the reflection axis direction of the reflective polarizer 140 is in the middle of the fast axis and the slow axis of the phase retarder 120, so that the light that passes through the phase retarder 120 and becomes linearly polarized is parallel to the reflection axis direction of the reflective polarizer 140.

[0050] In some examples, as shown in FIG4 , first lens 100, partial reflector 110, and phase retarder 120 may constitute a first lens assembly. For example, second lens 130, reflective polarizer 140, and light-transmitting structure 150 may constitute a second lens assembly. A gap is provided between the first lens assembly and the second lens assembly.

[0051] In some examples, the partial reflector 110 may be a semi-transmissive semi-reflective film. For example, the phase retarder 120 may be a quarter-wave plate.

[0052] In some examples, any of the partial reflector 110, the phase retarder 120, and the reflective polarizer 140 can have a flat or curved shape. For example, any of the partial reflector 110, the phase retarder 120, and the reflective polarizer 140 can be formed on a flat or curved lens. For example, the first lens 100 and the second lens 130 can be made of glass, plastic, or the like, although this is not a limitation in the present disclosure.

[0053] For example, as shown in Figures 4 and 5, after left-handed circularly polarized light 60 passes through the phase retarder 120 and is converted into second linearly polarized light 70, the reflective polarizer 140 reflects some of the polarized light perpendicular to the reflection axis, causing some of the second linearly polarized light 70 to be reflected by the reflective polarizer 140. However, the second linearly polarized light 70 is not used for imaging. Therefore, adding a light-transmitting structure 150 to the reflective polarizer 140 can reduce the reflection of the second linearly polarized light 70.

[0054] For example, as shown in Figures 4 and 5, after the right-handed circularly polarized light 20 passes through the phase retarder 120 to become the light 30 in the first linear polarization state, when there is an angle between the polarization direction of the light 30 in the first linear polarization state and the reflection axis direction of the reflective polarizer 140, for example, when there is a deviation in the alignment of the reflective polarizer 140 and the phase retarder 120, the polarization light component of the light 30 in the first linear polarization state perpendicular to the reflection axis will also be partially reflected by the reflective polarizer 140. Therefore, adding a transparent structure 150 to the reflective polarizer 140 can also reduce the reflection of the polarization light component perpendicular to the reflection axis.

[0055] In some examples, the angle between the lowest refraction direction of the light-transmitting structure 150 and the reflection axis direction can be 90 degrees, thereby minimizing the reflectivity of polarized light whose polarization direction is perpendicular to the reflection axis direction. Of course, the embodiments of the present disclosure are not limited to this. For example, the angle can also be any value between 70 degrees and 90 degrees.

[0056] In some examples, the reflectivity of a reflective polarizer for polarized light with a polarization direction perpendicular to the reflection axis is R⊥. For ease of explanation, it can be assumed that the reflection axis of the reflective polarizer is an isotropic optical medium with a refractive index of n. According to optical principles, the refractive index of the light-transmitting structure perpendicular to the reflection axis is n_low, and the thickness is t. If the following conditions are met at a certain wavelength λ: 1) 2) t = λ / (4*n_low), then the reflectivity at this wavelength is 0. Therefore, the light-transmitting structure can be designed and verified to determine n_low and t so that R⊥ is as small as possible, thereby minimizing the reflection of polarized light whose polarization direction is perpendicular to the reflection axis.

[0057] In some examples, the light-transmitting structure 150 has a highest refractive direction. The refractive index of the light-transmitting structure 150 for linearly polarized light parallel to the highest refractive direction is highest in the highest refractive direction, and the angle between the highest refractive direction and the reflection axis is less than or equal to 20 degrees. Since the refractive index of the light-transmitting structure 150 is generally lower than that of the reflective polarizer 140, adding a layer of a structure with a lower refractive index to the reflective polarizer 140 reduces the reflectivity of the reflective polarizer 140 in the direction of the reflection axis. By setting the angle between the highest refractive direction of the light-transmitting structure 150 and the reflection axis to be less than or equal to 20 degrees, the reduction in reflection of polarized light parallel to the reflection axis can be minimized. For example, the angle between the highest refractive direction and the reflection axis can be 0 degrees, thereby minimizing the reduction in reflection of polarized light parallel to the reflection axis by the light-transmitting structure 150. Of course, the embodiments of the present disclosure are not limited to this. For example, the angle can also be any value between 0 and 20 degrees.

[0058] In this example, while the light-transmitting structure 150 can reduce the reflectivity of polarized light perpendicular to the reflection axis, the angle between the highest reflection direction of the light-transmitting structure 150 and the reflection axis direction of the reflective polarizer 140 is less than or equal to 20 degrees, so that the influence on the reflectivity of polarized light parallel to the reflection axis is reduced to a minimum, and the influence of the light-transmitting structure 150 on the reflectivity of polarized light parallel to the reflection axis is minimized, so that the reflective polarizer 140 can have a larger reflection polarization ratio, and the light-transmitting structure 150 can be avoided from having an adverse effect on the optical efficiency of the optical module.

[0059] FIG6 is a partial top view of a laminated structure of a reflective polarizer and a light-transmitting structure provided in one embodiment of the present disclosure, and FIG7 is a partial cross-sectional view of the laminated structure shown in FIG6 . As shown in FIG6 and FIG7 , the light-transmitting structure 150 includes a first structural layer 151, which includes a plurality of first protrusions 152. In the thickness direction of the first structural layer 151, i.e., in the Z direction as shown in the figure, the first protrusions 152 protrude toward the first lens assembly or phase retarder 120. FIG6 and FIG7 schematically illustrate that the lowest refractive index of the light-transmitting structure 150 is in the X direction, and the highest refractive index is in the Y direction, but this is not a limitation of the present disclosure. The density of the first protrusions 152 in the first structural layer 151 along the lowest refractive index direction is less than the density of the first protrusions 152 in other directions within a reference plane, and the density of the first protrusions 152 along the highest refractive index direction is greater than the density of the first protrusions 152 in other directions within the reference plane. The reference plane is the plane containing the lowest and highest refractive index directions. Therefore, the density of the first protrusion 152 in the lowest refractive direction is the smallest, and polarized light parallel to the lowest refractive direction can pass through faster, so that the refractive index is the lowest; the density of the first protrusion 152 in the highest refractive direction is the largest, and polarized light parallel to the highest refractive direction is more difficult to pass through, so that the refractive index is the highest.

[0060] It should be noted that the density mentioned in the embodiments of the present disclosure refers to the degree of density. For example, if the density of the first protrusions 152 along the lowest refractive index direction is the lowest, it means that the first protrusions 152 are the most sparse along the lowest refractive index direction, and the number of first protrusions 152 per unit length along the lowest refractive index direction is the smallest. For example, if the density of the first protrusions 152 along the highest refractive index direction is the highest, it means that the first protrusions 152 are the most densely packed along the highest refractive index direction, and the number of first protrusions 152 per unit length along the highest refractive index direction is the largest.

[0061] In some examples, as shown in Figures 6 and 7, the reflection axis direction of the reflective polarizer 140 is the Y direction, and the transmission axis direction of the reflective polarizer 140 is the X direction. The density of the first protrusions 152 of the light-transmitting structure 150 in the X direction is the lowest, and the X direction is the lowest refractive direction of the light-transmitting structure 150. The density of the first protrusions 152 of the light-transmitting structure 150 in the Y direction is the highest, and the Y direction is the highest refractive direction of the light-transmitting structure 150. Thus, the lowest refractive direction of the light-transmitting structure 150 is perpendicular to the reflection axis direction, and the highest refractive direction of the light-transmitting structure 150 is parallel to the reflection axis direction. Of course, the embodiments of the present disclosure are not limited to this. Depending on the different manufacturing processes and materials of the light-transmitting structure 150, the arrangement and size of the first protrusions 152 may also vary.

[0062] In some examples, as shown in Figures 6 and 7, the size of the first protrusions 152 along the lowest refractive index direction is greater than the size of the first protrusions 152 along the highest refractive index direction. This can minimize the density of the first protrusions 152 in the lowest refractive index direction and maximize the density of the first protrusions 152 in the highest refractive index direction.

[0063] For example, as shown in FIG6 and FIG7, the ratio of the size of the first protrusion 152 along the lowest refractive direction to the size of the first protrusion 152 along the highest refractive direction is greater than or equal to 3. For example, the ratio may also be greater than or equal to 5.

[0064] In some examples, as shown in FIG6 , the orthographic projection of the first protrusion 152 on the reference plane includes a maximum dimension along the major axis M, and the angle between the major axis M of the plurality of first protrusions 152 and the lowest refractive index direction is less than or equal to 25 degrees. Thus, the smaller the angle between the major axis M of the first protrusion 152 and the lowest refractive index direction, the more the major axis M of the first protrusion 152 is biased toward the lowest refractive index direction, and the maximum dimension of the first protrusion 152 is arranged as close to the lowest refractive index direction as possible. This can effectively reduce the density of the first protrusions 152 in the lowest refractive index direction and minimize the refractive index in the lowest refractive index direction. For example, the angle between the major axis M of the plurality of first protrusions 152 and the lowest refractive index direction can be less than or equal to 15 degrees. For example, this angle can be any value within 25 degrees.

[0065] For example, Figure 6 schematically shows that the angle between the major axis direction M of each first protrusion 152 and the lowest refractive direction is 0 degrees, and the major axis directions M of multiple first protrusions 152 extend along the same direction, which is the lowest refractive direction. The maximum dimensions of the first protrusions 152 are arranged along the lowest refractive direction. Therefore, the density of the first protrusions 152 in the lowest refractive direction can be made smaller, and the refractive index in the lowest refractive direction can be made lower.

[0066] In some examples, as shown in Figures 6 and 7, the orthographic projection of the first protrusions 152 on the reference plane includes a short axis direction N perpendicular to the long axis direction M. The angle between the short axis directions N of the multiple first protrusions 152 and the direction of highest refraction is less than or equal to 25 degrees. Therefore, the smaller the angle between the short axis directions N of the first protrusions 152 and the direction of highest refraction, the more the short axis directions N of the first protrusions 152 are biased toward the direction of highest refraction. The short axes of the first protrusions 152 are arranged as close to the direction of highest refraction as possible, thereby increasing the density of the first protrusions 152 in the direction of highest refraction and achieving a higher refractive index in the direction of highest refraction. For example, the angle between the short axis directions N of the multiple first protrusions 152 and the direction of highest refraction can be less than or equal to 15 degrees. For example, this angle can be any value within 25 degrees.

[0067] For example, FIG6 schematically shows that the angle between the short axis direction N of each first protrusion 152 and the highest refraction direction is 0 degrees, and the short axis directions N of the plurality of first protrusions 152 extend along the same direction, which is the highest refraction direction.

[0068] It should be noted that the introduction of the major axis direction M and the minor axis direction N does not limit the orthographic projection of the first protrusion 152 on the reference plane to an ellipse. The major axis direction M is merely used to indicate the direction of the maximum dimension, while the minor axis direction N is perpendicular to the major axis direction M. For example, the minor axis of the first protrusion 152 can be defined as a line segment or chord obtained by intercepting the orthographic projection of the first protrusion 152 on the reference plane along the minor axis direction N, passing through the midpoint of the aforementioned maximum dimension. For example, the orthographic projection of the first protrusion 152 on the reference plane can be, but is not limited to, an ellipse and can also be other regular or irregular shapes.

[0069] In some examples, as shown in Figures 6 and 7 , the gap between two adjacent first protrusions 152 along the lowest refractive direction is larger than the gap between two adjacent first protrusions 152 along the highest refractive direction. This can better minimize the refractive index in the lowest refractive direction and maximize the refractive index in the highest refractive direction.

[0070] In some examples, as shown in Figures 6 and 7, the gap between two adjacent first protrusions 152 along the lowest refractive direction is larger than the gap between two adjacent first protrusions 152 in other directions in the reference plane, thereby minimizing the refractive index in the lowest refractive direction.

[0071] In some examples, the gap between two adjacent first protrusions 152 along the highest refraction direction is smaller than the gap between two adjacent first protrusions 152 in other directions in the reference plane, thereby maximizing the refractive index in the highest refraction direction.

[0072] In some examples, as shown in FIG6 , the plurality of first protrusions 152 overlap along the highest refraction direction, and overlap along the lowest refraction direction. Thus, the plurality of first protrusions 152 can be arranged more densely in the lowest and highest refraction directions, resulting in a laminated structure of the reflective polarizer 140 and the light-transmitting structure 150 having better optical performance, better reducing reflection perpendicular to the reflection axis, and minimizing the reduction in reflection of polarized light parallel to the reflection axis.

[0073] FIG8 is a partial top view of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure. As shown in FIG8 , the lowest refractive direction of the light-transmitting structure 150 is the X-direction. The long axis directions M of the multiple first protrusions 152 of the light-transmitting structure 150 are not arranged in the same direction. The long axis directions M of the multiple first protrusions 152 are different, and the shapes and sizes of the multiple first protrusions 152 are also different. However, the long axis directions M of the multiple first protrusions 152 of the light-transmitting structure 150 satisfy that the angle with the lowest refractive direction (i.e., the X-direction) is less than or equal to 25 degrees. Of course, the embodiment of the present disclosure is not limited to this. For example, the angle can also be less than or equal to 15 degrees.

[0074] For example, as shown in FIG8 , the highest refractive direction of the light-transmitting structure 150 is the Y direction, and the short-axis directions N of the multiple first protrusions 152 of the light-transmitting structure 150 are not arranged in the same direction, and the short-axis directions N of the multiple first protrusions 152 are different. However, the short-axis directions N of the multiple first protrusions 152 of the light-transmitting structure 150 satisfy that the angle with the highest refractive direction is less than or equal to 25 degrees. Of course, the embodiments of the present disclosure are not limited to this. For example, the angle can also be less than or equal to 15 degrees. FIG8 only exemplifies the arrangement of the multiple first protrusions 152 and does not limit the embodiments of the present disclosure.

[0075] Figure 9 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure. As shown in Figure 9, the sizes of the plurality of first protrusions 152 are unequal in the thickness direction of the first structural layer 151, i.e., in the Z direction as shown in the figure, although this is not a limitation of the present disclosure.

[0076] Figure 10 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided in one embodiment of the present disclosure. As shown in Figure 10, the first structural layer 151 further includes a base layer 153, and a plurality of first protrusions 152 are located on a side of the base layer 153 away from the reflective polarizer 140. The figure schematically illustrates that the dimensions of the plurality of first protrusions 152 in the Z and Y directions are the same, but this is not a limitation of the present disclosure and may be different.

[0077] In some examples, as shown in FIG10 , the base layer 153 and the plurality of first protrusions 152 are an integral structure. The light-transmitting structure 150 can be formed using film layers of different thicknesses. When the thickness of the film layer is relatively thin, for example, when the thickness of the film layer is within 300 nm, the first structure layer 151 can only include the plurality of first protrusions 152 (for example, as shown in FIG7 ). When the thickness of the film layer is relatively thick, for example, when the thickness of the film layer exceeds 300 nm, the first structure layer 151 can include a base layer 153, and the base layer 153 and the plurality of first protrusions 152 are made of the same material, and the base layer 153 and the plurality of first protrusions 152 are an integral structure.

[0078] Figure 11 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by one embodiment of the present disclosure. As shown in Figure 11, the base layer 153 is an adhesive layer, thereby allowing the first structural layer 151 to better adhere to the reflective polarizer 140. The present embodiment does not impose any restrictions on the material of the adhesive layer.

[0079] In some examples, as shown in Figure 11, the base layer 153 can be an optical device, thereby achieving optical functionality. For example, the refractive index of the base layer 153 can be greater than the refractive index of the reflective polarizing film. For example, the refractive index of the base layer 153 can also be greater than the refractive index of the structure where the plurality of first protrusions 152 are located. Of course, the embodiments of the present disclosure are not limited to this, and can be adjusted according to the design of the light-transmitting structure 150 and the optical module. It should be noted that the refractive index here refers to the refractive index in a certain polarization direction.

[0080] FIG12 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided in one embodiment of the present disclosure. As shown in FIG12 , the light-transmitting structure 150 further includes a second structural layer 154, which is stacked with the first structural layer 151 and located on the side of the first structural layer 151 away from the reflective polarizer 140. The second structural layer 154 includes a plurality of second protrusions 155. In the thickness direction of the second structural layer 154, i.e., in the Z direction as shown in the figure, the second protrusions 155 protrude toward the first lens assembly or phase retarder 120. By providing the second structural layer 154, the light-transmitting structure 150 can be optimized and designed in the thickness direction. For example, the refractive index of the light-transmitting structure 150 can be gradually changed in the thickness direction of the light-transmitting structure 150, so that the light-transmitting structure 150 can have a relatively good reflection reduction effect for as many wavelengths as possible.

[0081] 12 , the second protrusions 155 and the first protrusions 152 are made of different materials. For example, the orthographic projections of the second protrusions 155 on the reference plane fall within the orthographic projections of the first protrusions 152 on the reference plane.

[0082] Figure 13 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure. As shown in Figure 13, the second protrusions 155 and the first protrusions 152 are made of different materials. The orthographic projections of the plurality of second protrusions 155 within the reference plane fall within the orthographic projections of the plurality of first protrusions 152 within the reference plane. The first structural layer 151 also includes a base layer 153, which is made of the same material as the first protrusions 152. As a result, the refractive index of the light-transmitting structure 150 changes gradually and slowly across its thickness, effectively reducing reflection at all wavelengths.

[0083] Figure 14 is a partial cross-sectional schematic diagram of another laminated structure of a reflective polarizer and a light-transmitting structure provided by an embodiment of the present disclosure. As shown in Figure 14, second protrusions 155 and first protrusions 152 are made of different materials, and the orthographic projections of multiple second protrusions 155 on a reference plane overlap with the orthographic projections of multiple first protrusions 152 on the reference plane.

[0084] In some examples, the light-transmitting structure 150 may further include a multi-layer structure. For example, a third structural layer may be stacked on a side of the second structural layer 154 away from the first structural layer 151. The third structural layer may include a plurality of third protrusions. In the thickness direction of the third structural layer, the third protrusions protrude toward the first lens assembly or the phase retarder 120. This allows the light-transmitting structure 150 to be optimized and designed in the thickness direction. The structural design of the third protrusions is similar to that of the second protrusions 155 and will not be further described here. Of course, the embodiments of the present disclosure do not limit the number of layers of the multi-layer structure included in the light-transmitting structure 150.

[0085] In some examples, as shown in Figures 6 to 14 , the size of the first protrusion 152 along the thickness of the first structural layer 151 ranges from 50 nm to 300 nm. For example, the size can range from 70 nm to 150 nm. For example, the size can be any value between 50 nm and 300 nm. For example, as shown in Figures 12 to 14 , the size of the second protrusion 155 along the thickness of the second structural layer 154 ranges from 50 nm to 300 nm. For example, the size can be any value between 50 nm and 300 nm.

[0086] In some examples, as shown in Figures 6 to 14 , the maximum dimension of the first protrusion 152 in the long axis direction M ranges from a few nanometers to several hundred nanometers. For example, the dimension can be any value within the above range.

[0087] In some examples, as shown in Figures 6 to 14 , the size of the first protrusion 152 in the short axis direction N ranges from 1 nm to 80 nm. For example, the size can range from 5 nm to 30 nm. For example, the size can be any value between 1 nm and 80 nm.

[0088] In some examples, as shown in Figures 6 to 14, the gap between two adjacent first protrusions 152 has a value ranging from 1 nm to 80 nm. For example, the gap may have a value ranging from 5 nm to 30 nm. For example, the gap may have any value between 1 nm and 80 nm.

[0089] FIG15 is a schematic diagram of the partial structure of another laminated structure of a reflective polarizer and a light-transmitting structure provided in an embodiment of the present disclosure. As shown in FIG15 , a plurality of first protrusions 152 are connected so that the first structural layer 151 includes a plurality of first grooves 156. In order to clearly illustrate the arrangement and opening shape of the plurality of first grooves 156, FIG15 only auxiliaryly illustrates the inner dotted lines of three first grooves 156. FIG15 schematically illustrates that the lowest refractive direction of the light-transmitting structure 150 is the X direction, and the highest refractive direction of the light-transmitting structure 150 is the Y direction, but the embodiment of the present disclosure is not limited to this. The density of the first grooves 156 along the lowest refractive direction of the first structural layer 151 is less than the density of the first grooves 156 in other directions in the reference plane, and the density of the first grooves 156 along the highest refractive direction is greater than the density of the first grooves 156 in other directions in the reference plane. The reference plane is the plane where the lowest refractive direction and the highest refractive direction are located. Therefore, the density of the first grooves 156 in the lowest refractive direction is the smallest, and polarized light parallel to the lowest refractive direction can pass through faster, so that the refractive index is the lowest; the density of the first grooves 156 in the highest refractive direction is the largest, and polarized light parallel to the highest refractive direction is more difficult to pass through, so that the refractive index is the highest.

[0090] It should be noted that the density mentioned in the embodiments of the present disclosure refers to the degree of sparseness. For example, the lowest density of the first grooves 156 along the lowest refractive direction indicates that the first grooves 156 are the most sparse along the lowest refractive direction, and the number of first grooves 156 per unit length along the lowest refractive direction is the least. For example, the highest density of the first grooves 156 along the highest refractive direction indicates that the first grooves 156 are the most dense along the highest refractive direction, and the number of first grooves 156 per unit length along the highest refractive direction is the greatest.

[0091] In some examples, as shown in FIG15 , the Y direction is the reflection axis direction of the reflective polarizer 140, and the X direction is the transmission axis direction of the reflective polarizer 140. The density of the first grooves 156 of the light-transmitting structure 150 in the X direction is the lowest, and the X direction is the lowest refractive direction of the light-transmitting structure 150. The density of the first grooves 156 of the light-transmitting structure 150 in the Y direction is the highest, and the Y direction is the highest refractive direction of the light-transmitting structure 150. Thus, the lowest refractive direction of the light-transmitting structure 150 is perpendicular to the reflection axis direction, and the highest refractive direction of the light-transmitting structure 150 is parallel to the reflection axis direction. Of course, the embodiments of the present disclosure are not limited to this. Depending on the different manufacturing processes and materials of the light-transmitting structure 150, the arrangement and size of the first grooves 156 may also vary.

[0092] In some examples, as shown in FIG15 , the dimension of the first grooves 156 along the lowest refractive direction is greater than the dimension of the first grooves 156 along the highest refractive direction. This can minimize the density of the first grooves 156 in the lowest refractive direction and maximize the density of the first grooves 156 in the highest refractive direction.

[0093] In some examples, as shown in FIG. 15 , the ratio of the dimension of the first groove 156 along the lowest refractive direction to the dimension of the first groove 156 along the highest refractive direction is greater than or equal to 3. For example, the ratio may also be greater than or equal to 5.

[0094] In some examples, as shown in FIG15 , the orthographic projection of the first groove 156 on the reference plane includes a maximum dimension along the major axis M, and the angle between the major axis M of the plurality of first grooves 156 and the lowest refractive index direction is less than or equal to 25 degrees. Thus, the smaller the angle between the groove direction of the first protrusion 152 and the lowest refractive index direction, the more the major axis M of the first groove 156 is biased toward the lowest refractive index direction. The maximum dimension of the first grooves 156 is arranged as close to the lowest refractive index direction as possible, thereby reducing the density of the first grooves 156 in the lowest refractive index direction and achieving a lower refractive index in the lowest refractive index direction. For example, the angle between the major axis M of the plurality of first grooves 156 and the lowest refractive index direction can be less than or equal to 15 degrees. For example, this angle can be any value within 25 degrees.

[0095] For example, Figure 15 schematically shows that the angle between the long axis direction M of each first groove 156 and the lowest refractive direction is 0 degrees, and the long axis directions M of multiple first grooves 156 extend along the same direction, which is the lowest refractive direction. The maximum dimensions of the first grooves 156 are arranged along the lowest refractive direction, so that the density of the first grooves 156 in the lowest refractive direction can be better made smaller, and the refractive index in the lowest refractive direction can be made lower.

[0096] In some examples, as shown in FIG15 , the orthographic projection of the first grooves 156 on the reference plane includes a short axis direction N perpendicular to the long axis direction M, and the angle between the short axis directions N of the multiple first grooves 156 and the direction of highest refraction is less than or equal to 25 degrees. Thus, the smaller the angle between the short axis direction N of the first grooves 156 and the direction of highest refraction, the more the short axis direction N of the first grooves 156 is biased toward the direction of highest refraction, and the short axes of the first grooves 156 are arranged as close to the direction of highest refraction as possible, thereby increasing the density of the first grooves 156 in the direction of highest refraction and achieving a higher refractive index in the direction of highest refraction. For example, the angle between the short axis directions N of the multiple first grooves 156 and the direction of highest refraction can be less than or equal to 15 degrees. For example, the angle can be any value within 25 degrees.

[0097] For example, FIG15 schematically shows that the angle between the short axis direction N of each first groove 156 and the highest refractive direction is 0 degrees, and the short axis directions N of the plurality of first grooves 156 extend along the same direction, which is the highest refractive direction.

[0098] It should be noted that the introduction of the major axis direction M and the minor axis direction N does not limit the orthographic projection of the first groove 156 on the reference plane to an ellipse. The major axis direction M is merely used to indicate the direction of the maximum dimension, while the minor axis direction N is perpendicular to the major axis direction M. For example, the minor axis of the first groove 156 can be defined as a line segment or chord obtained by intercepting the orthographic projection of the first groove 156 on the reference plane along the minor axis direction N, passing through the midpoint of the aforementioned maximum dimension. For example, the orthographic projection of the first groove 156 on the reference plane can be, but is not limited to, an ellipse and can also be other regular or irregular shapes.

[0099] In some examples, as shown in FIG15 , the gap between two adjacent first grooves 156 along the lowest refractive index direction is larger than the gap between two adjacent first grooves 156 along the highest refractive index direction. This can minimize the density of the first grooves 156 in the lowest refractive index direction and maximize the density of the first grooves 156 in the highest refractive index direction.

[0100] In some examples, as shown in FIG15 , the gap between two adjacent first grooves 156 along the lowest refractive direction is larger than the gap between two adjacent first grooves 156 in other directions in the reference plane, thereby minimizing the refractive index in the lowest refractive direction.

[0101] In some examples, the gap between two adjacent first grooves 156 along the highest refractive direction is smaller than the gap between two adjacent first grooves 156 in other directions in the reference plane, thereby maximizing the refractive index in the highest refractive direction.

[0102] In some examples, as shown in FIG15 , the plurality of first grooves 156 overlap along the highest refractive direction, and overlap along the lowest refractive direction. Thus, the plurality of first grooves 156 can be arranged more densely in the lowest and highest refractive directions, thereby improving the optical performance of the laminated structure of the reflective polarizer 140 and the light-transmitting structure 150, effectively reducing reflection perpendicular to the reflection axis, and minimizing the reduction in reflection of polarized light parallel to the reflection axis.

[0103] In some examples, the major axis directions M of the multiple first grooves 156 of the light-transmitting structure 150 may not be arranged in the same direction, the major axis directions M of the multiple first grooves 156 may be different, and the shapes and sizes of the multiple first grooves 156 may be different. However, the major axis directions M of the multiple first grooves 156 of the light-transmitting structure 150 satisfy that the angle between the major axis directions M and the lowest refractive direction (i.e., the X direction) is less than or equal to 25 degrees. Of course, the embodiments of the present disclosure are not limited to this. For example, the angle may also be less than or equal to 15 degrees.

[0104] In some examples, the short axis directions N of the multiple first grooves 156 of the light-transmitting structure 150 may not be arranged in the same direction, and the short axis directions N of the multiple first grooves 156 may also be different. However, the short axis directions N of the multiple first grooves 156 of the light-transmitting structure 150 satisfy that the angle between the short axis directions N and the highest refraction direction is less than or equal to 25 degrees. Of course, the embodiments of the present disclosure are not limited to this. For example, the angle may also be less than or equal to 15 degrees.

[0105] In some examples, as shown in FIG. 15 , the depths of the plurality of first grooves 156 may be unequal, which is not limited in the present disclosure.

[0106] In some examples, the plurality of second protrusions 155 of the second structural layer 154 included in the light-transmitting structure 150 may also be connected so that the second structural layer 154 includes a plurality of second grooves, and the orthographic projections of the plurality of first grooves 156 on the reference plane fall within the orthographic projections of the plurality of second grooves on the reference plane, or the orthographic projections of the plurality of first grooves 156 on the reference plane overlap with the orthographic projections of the plurality of second grooves on the reference plane. Thus, the light-transmitting structure 150 can be optimized and designed along its thickness. For example, the refractive index of the light-transmitting structure 150 can gradually change along its thickness, so that the light-transmitting structure 150 can achieve a relatively good reflection reduction effect for as many wavelengths as possible.

[0107] In some examples, by adjusting the size or density of the first protrusions 152, the second protrusions 155, the first grooves 156, or the second grooves, the refractive index of the light-transmitting structure 150 perpendicular to the reflection axis can be adjusted to be as low as possible or minimized, thereby minimizing the reflectivity of the reflective polarizer 140 perpendicular to the reflection axis. For example, the refractive index of the light-transmitting structure 150 perpendicular to the reflection axis can be in the range of 1.15-1.35, or in the range of 1.20-1.30. For example, the refractive index can be any value between 1.15-1.35.

[0108] Figure 16 compares the reflective polarization selectivity of a reflective polarizer and a light-transmitting structure provided in one embodiment of the present disclosure. As shown in Figure 16, based on average values, the reflectivities (R⊥) perpendicular to the reflection axis for reflective polarizers 1 and 2 are 10.99% and 9%, respectively. Polarized light perpendicular to the reflection axis will also be reflected, resulting in undesirable visual effects such as stray light and ghosting, which can affect the visual experience.

[0109] After adding an isotropic anti-reflection coating to the reflective polarizer 1, for example, using three different isotropic anti-reflection coatings, anti-reflection coatings 1, 2, and 3, the reflectivity perpendicular to the reflection axis (R⊥) decreased slightly compared to the case without the anti-reflection coating, with the values ​​of R⊥ being 6.41%, 8.27%, and 7.41%, respectively. The reflective polarization selectivity (R / / / R⊥) also increased compared to the case without the anti-reflection coating. However, the reflectivity parallel to the reflection axis (R / / ) decreased significantly, which affected the optical efficiency.

[0110] After adding the light-transmitting structure provided by the embodiment of the present disclosure to the reflective polarizer 1, its reflectivity (R⊥) perpendicular to the reflection axis is 4%, which is significantly lower than the reflectivity (R⊥) perpendicular to the reflection axis after adding the isotropic anti-reflection film. At the same time, its reflectivity (R / / ) parallel to the reflection axis is 96%, both of which are significantly higher than the reflectivity (R / / ) parallel to the reflection axis after adding the isotropic anti-reflection film, and the decrease is very small compared to the reflectivity (R / / ) parallel to the reflection axis of the reflective polarizer without adding the anti-reflection film. The reflective polarization selectivity (R / / / R⊥) is also significantly improved. In this example, the reflective polarization selectivity is 24, which is basically twice the reflective polarization selectivity after adding the isotropic anti-reflection film. This can reduce the reflectivity of polarized light perpendicular to the reflection axis without adversely affecting the optical efficiency.

[0111] One embodiment of the present disclosure also provides a near-eye display device. FIG17 is a schematic structural diagram of a near-eye display device provided by one embodiment of the present disclosure. As shown in FIG17 , the near-eye display device includes any of the above-mentioned optical modules and a display 200. The display 200 is located on the light incident side of the optical module. A polarizer 210 is provided on the side of the display close to the optical module. The polarizer 210 is configured to polarize the light emitted from the display into circularly polarized light. As a result, the near-eye display device has beneficial effects corresponding to the beneficial effects of the optical module, which will not be described in detail here.

[0112] An embodiment of the present disclosure further provides a method for manufacturing an optical module. FIG18 is a flow chart of a method for manufacturing an optical module provided in an embodiment of the present disclosure. The optical module has a light input side and a light output side, as shown in FIG18 . The method for manufacturing the optical module includes:

[0113] S1: Provide the first lens;

[0114] S2: providing a partial reflector on the side of the first lens close to the light incident side;

[0115] S3: providing a phase retarder on a side of the first lens away from the partial reflector, wherein the phase retarder is configured to convert the circularly polarized light into a linearly polarized light or convert the linearly polarized light into a circularly polarized light;

[0116] S4: providing a second lens on a side of the phase retarder away from the first lens;

[0117] S5: providing a reflective polarizer on a side of the second lens close to the phase retarder; and

[0118] S6: A light-transmitting structure is provided on the side of the reflective polarizer close to the phase retarder, and a gap is set between the light-transmitting structure and the phase retarder.

[0119] The partial reflector in this manufacturing method is configured to transmit light incident from the light incident side, and is configured to reflect light incident from the phase retarder and change the polarization state of the light. The reflective polarizer has a reflection axis direction and a transmission axis direction that are perpendicular to each other. The reflective polarizer reflects linearly polarized light parallel to the reflection axis direction in the reflection axis direction and keeps the polarization state of the linear polarized light unchanged. The reflective polarizer transmits linearly polarized light parallel to the transmission axis direction in the transmission axis direction and keeps the polarization state of the linear polarized light unchanged. The light-transmitting structure has a lowest refractive direction. The refractive index of the light-transmitting structure for linearly polarized light parallel to the lowest refractive direction is the lowest in the lowest refractive direction. The angle between the lowest refractive direction and the reflection axis direction is greater than or equal to 70 degrees and less than or equal to 90 degrees. Therefore, for polarized light with a polarization direction perpendicular to the reflection axis, since the transparent structure has the lowest refraction direction, the reflection of the polarized light with a polarization direction perpendicular to the reflection axis can be reduced, the reflection polarization ratio of the reflective polarizing film can be improved, and the polarized light with a polarization direction perpendicular to the reflection axis can be reduced from entering the folded light path, thereby avoiding the occurrence of phenomena such as stray light and ghosting that affect the visual experience, and improving the clarity, contrast and visual experience of the near-eye display device where the optical module is located.

[0120] In some examples, a first lens assembly can be formed by sequentially performing steps S1, S2, and S3. For example, a second lens assembly can be formed by sequentially performing steps 4, 5, and 6. A gap is set between the first lens assembly and the second lens assembly.

[0121] For example, providing a light-transmitting structure on a side of the reflective polarizer adjacent to the phase retarder includes forming a light-transmitting structure on a side of the reflective polarizer adjacent to the phase retarder.

[0122] FIG19 is a flow chart of a method for forming a light-transmitting structure on one side of a reflective polarizer according to an embodiment of the present disclosure. As shown in FIG19 , forming a light-transmitting structure on one side of a reflective polarizer includes the following steps:

[0123] S100: forming an imprint pattern having structural features opposite to those of the light-transmitting structure on an imprint template so as to form a light-transmitting structure through the imprint template;

[0124] S200: applying a material layer on the side of the imprint template having the imprint pattern;

[0125] S300: Aligning and laminating the uncured material layer and the reflective polarizer so that the angle between the lowest refraction direction of the formed light-transmitting structure and the reflection axis direction of the reflective polarizer is greater than or equal to 70 degrees and less than or equal to 90 degrees;

[0126] S400: curing the material layer to form a light-transmitting structure on one side of the reflective polarizer;

[0127] S500: removing the imprint template.

[0128] In the manufacturing method provided in the present embodiment, the material layer and the reflective polarizer are aligned and bonded so that the angle between the lowest refraction direction of the light-transmitting structure formed on the reflective polarizer and the reflection axis direction of the reflective polarizer is greater than or equal to 70 degrees and less than or equal to 90 degrees. Therefore, when the reflective polarizer and the light-transmitting structure are used in the above-mentioned optical module, the reflectivity of the polarized light perpendicular to the reflection axis direction can be reduced while the influence of the light-transmitting structure on the reflectivity of the polarized light parallel to the reflection axis direction can be minimized. This allows the reflective polarizer to have a larger reflection polarization ratio, reduces the polarized light with a polarization direction perpendicular to the reflection axis direction from entering the folded light path, avoids the occurrence of phenomena such as stray light and ghosting that affect the visual experience, and improves the clarity, contrast and visual experience of the near-eye display device where the optical module is located.

[0129] For example, the imprint template can be a polymer soft template, for example, the material of the imprint template can be a material that can transmit ultraviolet light, for example, the material of the imprint template can be polydimethylsiloxane (PDMS), for example, the imprint template can be transferred from a hard template formed by electron beam etching.

[0130] For example, the material layer can be a transparent polymer layer. For example, the material layer can be a UV-curable organic resin formulation, for example, composed of primary components such as acrylic monomers, acrylic polymers, crosslinking agents, and UV initiators. For example, in addition to the aforementioned acrylic-based polymer materials, polymer materials such as liquid crystal polymers, polyesters, and polysiloxanes, as well as inorganic materials such as titanium dioxide, zirconium dioxide, aluminum oxide, and silicon nitride can also be used, without limitation.

[0131] For example, the material layer may be formed by slit coating, dimple coating, or spin coating.

[0132] For example, the imprint template may be adjusted so that the uncured material layer is aligned and attached to the reflective polarizer. For example, the reflective polarizer may be adjusted so that the uncured material layer is aligned and attached to the reflective polarizer.

[0133] For example, ultraviolet light may be applied to cure the material layer so that the material layer and the reflective polarizer have a stronger bonding force than that between the material layer and the imprint template.

[0134] FIG20 is a schematic diagram of another manufacturing method for forming a light-transmitting structure on one side of a reflective polarizer according to an embodiment of the present disclosure. As shown in FIG20 , an anisotropic embossing pattern 310 is formed on an imprint template 300, wherein the embossing pattern 310 has structural features opposite to those of the light-transmitting structure 150. A material layer 320 is applied to the side of the imprint template 300 having the embossing pattern 310. The uncured material layer 320 is aligned and attached to the reflective polarizer 140 so that the angle between the lowest refractive direction of the formed light-transmitting structure 150 and the reflection axis direction of the reflective polarizer 140 is greater than or equal to 70 degrees and less than or equal to 90 degrees. Ultraviolet light (UV) is applied to cure the material layer 320 to form the light-transmitting structure 150 on the reflective polarizer 140. The imprint template is removed, thereby forming the reflective polarizer 140 with the light-transmitting structure 150.

[0135] In some examples, the embossing template may also be a cylindrical roller structure, and the embossing pattern may be formed on the cylindrical roller structure. For example, the embossing pattern may be transferred to the material layer by roller pressing.

[0136] In some examples, a material layer may be coated on the reflective polarizer, and then an imprint template may be used to imprint on the material layer to form a light-transmitting structure.

[0137] In some examples, a "top-down" method, such as photolithography or self-assembled template etching, in which a material layer is first formed and then etched, can be used to form a light-transmitting structure on the reflective polarizer. For example, a "bottom-up" method, such as bevel coating or liquid crystal coating, can also be used to form a light-transmitting structure on the reflective polarizer.

[0138] There are a few points to note:

[0139] (1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure, and other structures may refer to conventional designs.

[0140] (2) Unless there is any conflict, the features of the same embodiment and different embodiments of the present disclosure may be combined with each other.

[0141] The above are only specific embodiments of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. An optical module having a light incident side and a light emitting side, comprising: First lens; a partial reflector, disposed on a side of the first lens close to the light incident side; a phase retarder, disposed on a side of the first lens away from the partial reflector, configured to convert circularly polarized light into linearly polarized light, or to convert linearly polarized light into circularly polarized light; A second lens is arranged on a side of the phase retarder away from the first lens; a reflective polarizer, disposed on a side of the second lens close to the phase retarder; as well as A light-transmitting structure is arranged on a side of the reflective polarizer close to the phase retarder and is spaced apart from the phase retarder. The partial reflector is configured to transmit light incident from the light incident side, and is configured to reflect light incident from the phase retarder and change the polarization state of the light, the reflective polarizer has a reflection axis direction and a transmission axis direction perpendicular to each other, the reflective polarizer reflects linear polarized light parallel to the reflection axis direction in the reflection axis direction and keeps the polarization state of the linear polarized light unchanged, and the reflective polarizer transmits linear polarized light parallel to the transmission axis direction in the transmission axis direction and keeps the polarization state of the linear polarized light unchanged, The light-transmitting structure has a lowest refractive direction, and the light-transmitting structure has a lowest refractive index in the lowest refractive direction for linearly polarized light parallel to the lowest refractive direction. The angle between the lowest refraction direction and the reflection axis direction is greater than or equal to 70 degrees and less than or equal to 90 degrees.

2. The optical module according to claim 1, wherein: The light-transmitting structure has a highest refractive direction, and the light-transmitting structure has a highest refractive index in the highest refractive direction for linearly polarized light parallel to the highest refractive direction. The angle between the highest refraction direction and the reflection axis direction is less than or equal to 20 degrees.

3. The optical module according to claim 2, wherein: The light-transmitting structure includes a first structural layer, the first structural layer includes a plurality of first protrusions, and in a thickness direction of the first structural layer, the first protrusions protrude toward a direction close to the phase retarder, The density of the first protrusions of the first structural layer along the lowest refractive direction is smaller than the density of the first protrusions in other directions on the reference plane, and the density of the first protrusions along the highest refractive direction is larger than the density of the first protrusions in other directions on the reference plane. The reference plane is a plane where the lowest refraction direction and the highest refraction direction are located.

4. The optical module according to claim 3, wherein: A size of the first protrusion along the lowest refraction direction is greater than a size of the first protrusion along the highest refraction direction.

5. The optical module according to claim 4, wherein: The orthographic projection of the first protrusion on the reference plane includes a maximum dimension along the long axis direction, and an angle between the long axis direction of the plurality of first protrusions and the lowest refraction direction is less than or equal to 25 degrees.

6. The optical module according to claim 5, wherein: The orthographic projection of the first protrusion on the reference plane includes a short axis direction perpendicular to the long axis direction, and an angle between the short axis directions of the first protrusions and the highest refraction direction is less than or equal to 25 degrees.

7. The optical module according to claim 3, wherein: A gap between two adjacent first protrusions along the lowest refraction direction is greater than a gap between two adjacent first protrusions along the highest refraction direction.

8. The optical module according to any one of claims 3 to 7, wherein: The first structure layer further includes a base layer, and the plurality of first protrusions are located on a side of the base layer away from the reflective polarizer.

9. The optical module according to claim 8, wherein: The base layer and the plurality of first protrusions are an integral structure.

10. The optical module according to any one of claims 3 to 9, wherein: The light-transmitting structure further includes a second structural layer, which is stacked with the first structural layer and is located on a side of the first structural layer away from the reflective polarizer. The second structure layer includes a plurality of second protrusions. In a thickness direction of the second structure layer, the second protrusions protrude toward a direction close to the phase retarder.

11. The optical module according to claim 10, wherein: The second protrusions and the first protrusions are made of different materials, the orthographic projections of the plurality of second protrusions on the reference plane fall within the orthographic projections of the plurality of first protrusions on the reference plane, or the orthographic projections of the plurality of second protrusions on the reference plane overlap with the orthographic projections of the plurality of first protrusions on the reference plane.

12. The optical module according to claim 10, wherein: The second protrusions are made of different materials from the first protrusions, the orthographic projections of the plurality of second protrusions on the reference plane fall within the orthographic projections of the plurality of first protrusions on the reference plane, and the first structural layer further comprises a base layer, which is made of the same material as the first protrusions.

13. The optical module according to any one of claims 3 to 12, wherein: Along the thickness of the first structural layer, the size of the first protrusion ranges from 50nm to 300nm. The gap between two adjacent first protrusions is less than or equal to 80 nm.

14. The optical module according to any one of claims 3 to 13, wherein: Along the highest refraction direction, the plurality of first protrusions overlap, and along the lowest refraction direction, the plurality of first protrusions overlap.

15. The optical module according to any one of claims 3 to 14, wherein: The multiple first protrusions are connected so that the first structural layer includes multiple first grooves, the density of the first grooves of the first structural layer along the lowest refractive direction is less than the density of the first grooves in other directions on the reference plane, and the density of the first grooves along the highest refractive direction is greater than the density of the first grooves in other directions on the reference plane.

16. A near-eye display device, comprising: The optical module according to any one of claims 1 to 15, and A display, located on the light incident side of the optical module, Wherein, a polarizer is disposed on a side of the display close to the optical module, and the polarizer is configured to polarize light emitted from the display into circularly polarized light.

17. A method for manufacturing an optical module, the optical module having a light incident side and a light emitting side, the manufacturing method comprising: providing a first lens; Providing a partial reflector on a side of the first lens close to the light incident side; A phase retarder is provided on a side of the first lens away from the partial reflector, wherein the phase retarder is configured to change the light in a circular polarization state into the light in a linear polarization state or change the light in a linear polarization state into the light in a circular polarization state; Providing a second lens on a side of the phase retarder away from the first lens; providing a reflective polarizer on a side of the second lens adjacent to the phase retarder; A light-transmitting structure is provided on a side of the reflective polarizer close to the phase retarder, and a gap is set between the light-transmitting structure and the phase retarder. The partial reflector is configured to transmit light incident from the light incident side, and is configured to reflect light incident from the phase retarder and change the polarization state of the light, the reflective polarizer has a reflection axis direction and a transmission axis direction perpendicular to each other, the reflective polarizer reflects linear polarized light parallel to the reflection axis direction in the reflection axis direction and keeps the polarization state of the linear polarized light unchanged, and the reflective polarizer transmits linear polarized light parallel to the transmission axis direction in the transmission axis direction and keeps the polarization state of the linear polarized light unchanged, The light-transmitting structure has a lowest refractive direction, and the light-transmitting structure has a lowest refractive index in the lowest refractive direction for linearly polarized light parallel to the lowest refractive direction. The angle between the lowest refraction direction and the reflection axis direction is greater than or equal to 70 degrees and less than or equal to 90 degrees.

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