Turn-back type optical assembly and optical module
By using reflective polarization film and reciprocating polarization rotator in head-mounted display devices, the problem of low light efficiency is solved, efficient rewinding of the optical path is achieved, and the light efficiency of the optical system is improved.
Patent Information
- Application Number
- CN202422309910.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-20
- Publication Date
- 2025-08-08
- Estimated Expiration
- 2034-09-20
AI Technical Summary
Among the existing head-mounted display devices, the light efficiency of the foldback optical system is low, mainly because the spectroscopic film can only transmit half of the polarized light, resulting in light loss.
Reflective polarization film is used instead of the spectroscopic film, and combined with a reciprocal polarization rotator and a non-reciprocal polarization rotator, the rewinding of the optical path is achieved, the spectroscopic film is eliminated, and the light effect is increased.
The light efficiency of the foldback optical components is greatly improved, light loss is reduced, and optical performance of the optical system is enhanced.
Smart Images
Figure CN223205720U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of head-mounted display devices, in particular to a folding optical component and an optical module. Background Art
[0002] In order to reduce the thickness of the module, existing head-mounted display devices usually use a folding optical system consisting of a beam splitter film (BS film) and a reflective polarizing film (RP film) to fold the system's optical path, causing the light to be reflected between the beam splitter film and the reflective polarizing film and finally enter the human eye.
[0003] However, since the beam splitter film can only transmit half of the polarized light and reflect the other half, the light emitted from the transmitting end is lost, resulting in low light efficiency of the reflective optical system. Utility Model Content
[0004] Based on this, it is necessary to provide a folding optical component and optical module to address the problem of low light efficiency in existing head-mounted display devices.
[0005] A folding optical assembly, comprising:
[0006] a first reflective polarizing element configured to transmit the first linearly polarized light and reflect a third linearly polarized light having a polarization direction perpendicular to the polarization direction of the first linearly polarized light;
[0007] a reciprocal polarization rotator having an optical axis angle of 45°, configured to rotate the polarization direction of linearly polarized light transmitted along the first direction in a forward direction by 45°, and to rotate the polarization direction of linearly polarized light transmitted along a second direction opposite to the first direction in a reverse direction by 45°;
[0008] a non-reciprocal polarization rotator, wherein the optical axis angle of the non-reciprocal polarization rotator is 45°, and is used to rotate the polarization direction of the linearly polarized light transmitted along the first direction or the second direction in a positive direction by 45°; and
[0009] The second reflective polarizing element has a reflection axis direction that is the same as that of the first reflective polarizing element, and is configured to transmit the first linearly polarized light and reflect the third linearly polarized light.
[0010] In one embodiment, the output component includes an output end and a polarizer sequentially arranged along a first direction, and the polarizer is used to modulate the linearly polarized light emitted by the output end into a first linearly polarized light.
[0011] In one embodiment, the polarizer is an iodine-based polarizer.
[0012] In one embodiment, the folding optical component further includes a lens, the folding optical component further includes a first lens and a second lens, the first reflective polarizing element is compounded with the reciprocal polarization rotator and attached to the first lens, and the second reflective polarizing element and the non-reciprocal polarization rotator are attached to the second lens.
[0013] In one embodiment, the folding optical assembly further includes a third lens and a fourth lens, the first reflective polarizing element is attached to the third lens; the second reflective polarizing element, the non-reciprocal polarization rotator and the reciprocal polarization rotator are combined and attached to the fourth lens.
[0014] In one embodiment, the reflection axis direction of the first reflective polarizing element is vertical, and is used to reflect linearly polarized light with a vertical polarization direction and transmit linearly polarized light with a horizontal polarization direction.
[0015] In one embodiment, the first reflective polarizing element is a reflective polarizing film, and the second reflective polarizing element is a reflective polarizing film.
[0016] In one embodiment, the reciprocal polarization rotator is a half-wave plate.
[0017] In one embodiment, the non-reciprocal polarization rotator is a Faraday rotator.
[0018] An optical module, comprising:
[0019] an output component for emitting a first linearly polarized light; and
[0020] As in any of the above-mentioned folding optical components, the folding optical component is arranged on the light-emitting side of the output component along the first direction.
[0021] In one embodiment, the output component includes an output end and a polarizer sequentially arranged along the first direction, and the polarizer is used to modulate the linearly polarized light emitted by the output end into the first linearly polarized light.
[0022] In one embodiment, the polarizer is an iodine-based polarizer.
[0023] The above-mentioned folding optical component eliminates the beam splitter film (BS film) and replaces the beam splitter film with a reflective polarizing film (RP film), and adds a reciprocal polarization rotator and a non-reciprocal polarization rotator, thereby greatly improving the light efficiency of the folding optical component while realizing the light path folding. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 A schematic structural diagram of an optical module provided in one embodiment of the present application;
[0025] Figure 2 A schematic structural diagram of a modified embodiment of the optical module according to the above embodiment of the present application is shown;
[0026] Figure 3 A structural schematic diagram of another modified embodiment of the optical module according to the above embodiment of the present application is shown.
[0027] Figure numerals: 11, output end; 111, first linear polarized light; 112, second linear polarized light; 113, third linear polarized light; 114, fourth linear polarized light; 12, polarizer; 13, first reflective polarizing element; 14, reciprocal polarization rotator; 15, non-reciprocal polarization rotator; 16, second reflective polarizing element; 17, human eye; 21, first lens; 22, second lens; 23, third lens; 24, fourth lens; 31, first path; 32, second path; 33, third path. DETAILED DESCRIPTION
[0028] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.
[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.
[0031] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, optical connection, or polarization connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.
[0032] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.
[0033] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.
[0034] Based on the problem of low light efficiency in existing head-mounted display devices, the present application provides a folding optical component and an optical module. The optical module includes an output component and a folding optical component. The folding optical component is arranged on the light-emitting side of the output component along a first direction, and the output component is used to emit a first linearly polarized light. The folding optical component eliminates the beam splitter film (BS film) and replaces the beam splitter film with a reflective polarizing film (RP film), and adds a reciprocal polarization rotator and a non-reciprocal polarization rotator, thereby greatly improving the light efficiency of the folding optical component while achieving light path folding.
[0035] For details, please refer to Figure 1The folding optical component may include a first reflective polarizing element 13, a reciprocal polarization rotator 14, a non-reciprocal polarization rotator 15, and a second reflective polarizing element 16 arranged in sequence along a first direction; the first reflective polarizing element 13 is used to transmit the first linearly polarized light 111 and reflect the third linearly polarized light 113 whose polarization direction is perpendicular to the polarization direction of the first linearly polarized light 111; the optical axis angle of the reciprocal polarization rotator 14 is 45°, and is used to rotate the polarization direction of the linearly polarized light transmitted along the first direction in the positive direction by 45°, so that the polarization direction of the linearly polarized light transmitted along the first direction is perpendicular to the polarization direction of the first linearly polarized light 111. The polarization direction of the linearly polarized light transmitted in the opposite second direction is reversely rotated by 45°. The optical axis angle of the non-reciprocal polarization rotator 15 is 45°, and is used to rotate the polarization direction of the linearly polarized light transmitted along the first direction or the second direction in the forward direction by 45°. The reflection axis direction of the second reflective polarizing element 16 is the same as the reflection axis direction of the first reflective polarizing element 13, and is used to transmit the linearly polarized light perpendicular to the polarization direction of the first linearly polarized light 111 and reflect the third linearly polarized light 113 perpendicular to the polarization direction of the first linearly polarized light 111.
[0036] It can be understood that, based on the principle that the reciprocal polarization rotator 14 and the non-reciprocal polarization rotator 15 have different optical rotation effects in different propagation directions, when the linearly polarized light passes through the reciprocal polarization rotator 14 and the non-reciprocal polarization rotator 15 in sequence along the first direction, the polarization direction of the linearly polarized light is rotated 45° twice in the forward direction, that is, the polarization direction of the linearly polarized light is rotated 90°; when the linearly polarized light passes through the non-reciprocal polarization rotator 15 and the reciprocal polarization rotator 14 in sequence along the second direction, the polarization direction of the linearly polarized light is rotated 45° in the forward direction and then rotated 45° in the reverse direction. , that is, the polarization direction of the linear polarized light remains unchanged; and in the fold-back optical component of the present application, the reflection axis direction of the first reflective polarizing element 13 and the second reflective polarizing element 16 is the same as the polarization direction of the linear polarized light that can be transmitted by the first reflective polarizing element 13, and the fold-back optical component uses the reciprocal polarization rotator 14 and the non-reciprocal polarization rotator 15 to form three fold-back paths between the first reflective polarizing element 13 and the second reflective polarizing element 16, wherein the first path 31 and the third path 33 are along the first direction, and the second path 32 is along the second direction.
[0037] After passing through the first polarization reflective element, the first linearly polarized light 111 emitted by the output assembly passes through the first polarization reflective element, sequentially passes through the reciprocal polarization rotator 14 and the non-reciprocal polarization rotator 15 along a first path 31, with its polarization direction rotated 90°. The light is then reflected by the second polarization reflective element. The light passes through the non-reciprocal polarization rotator 15 and the reciprocal polarization rotator 14 along a second path 32, with its polarization direction unchanged. The light is then reflected by the first polarization reflective element. The light passes through the reciprocal polarization rotator 14 and the non-reciprocal polarization rotator 15 along a third path 33, with its polarization direction rotated 90°. The light then passes through the second polarization reflective element and reaches the human eye 17, thereby completing the optical path reversal.
[0038] It is worth noting that the first direction in this application is the direction from the output component to the human eye 17, that is, Figure 1 The second direction is the direction from the human eye 17 to the output component, that is, Figure 1 From left to right in the direction.
[0039] Optionally, in some embodiments, the output component includes an output end 11 and a polarizer 12 arranged in sequence along a first direction, the polarizer 12 can absorb polarized light in one polarization direction and allow linear polarized light perpendicular to this polarization direction to pass through, the output end 11 can emit linear polarized light, and the polarizer 12 can modulate the linear polarized light emitted by the output end 11 into a first linear polarized light 111.
[0040] By way of example, the output terminal 11 may be implemented as a screen.
[0041] Preferably, in one embodiment, the polarizer 12 can be implemented as an iodine-based polarizer 12. Based on the good polarization property of iodine ions, after being adsorbed on linearly arranged molecular chains, they can absorb linearly polarized light parallel to the arrangement direction of the iodine ions and only allow linear polarized light perpendicular to the arrangement direction to pass through.
[0042] Optionally, in some embodiments, the first reflective polarizing element 13 is a reflective polarizing film. The reflective polarizing film can reflect linearly polarized light in one polarization direction and transmit linearly polarized light perpendicular to the polarization direction. The reflective polarizing film can be formed by stacking two media with different properties multiple times, using processes such as co-extrusion and stretching. Stretching of one of the media in the reflective polarizing film changes its refractive index in the stretching direction, resulting in birefringence. The refractive index of the other media remains unchanged after stretching, thereby reflecting linearly polarized light in the stretching direction and transmitting linearly polarized light perpendicular to the stretching direction.
[0043] Likewise, in some embodiments, the second reflective polarizing element 16 is a reflective polarizing film.
[0044] Optionally, in some embodiments, based on the characteristic that linearly polarized light undergoes the same rotation angle but opposite rotation directions after passing through the reciprocal polarization rotator 14 in the first direction and the second direction, the reciprocal polarization rotator 14 can be implemented as a half-wave plate. A half-wave plate is a birefringent crystal. When linearly polarized light passes through it, the ordinary light and the extraordinary light have different refractive indices, with a phase difference of an odd multiple of π. When the angle between the optical axis of the linearly polarized light and the optical axis of the half-wave plate is α, the polarization direction of the linearly polarized light rotates by 2α after passing through the half-wave plate, resulting in a 45° rotation of the linearly polarized light after passing through the half-wave plate.
[0045] Optionally, in some embodiments, based on the characteristic that the rotation angle and rotation direction of linearly polarized light remain the same after passing through the non-reciprocal polarization rotator 15 in a first direction and the reciprocal polarization rotator 14 in a second direction, the non-reciprocal polarization rotator 15 can be implemented as a Faraday rotator. A Faraday rotator utilizes the Faraday effect. When a magnetic field is applied to a transparent medium, the electromagnetic properties of light cause it to rotate more easily in one direction than in the other. By controlling the direction and propagation distance of the magnetic field, the rotation angle of linearly polarized light passing through the Faraday rotator can be controlled to be 45°.
[0046] Optionally, in some embodiments, the reflection axis direction of the first reflective polarizing element 13 is vertical, and is configured to reflect linearly polarized light with a vertical polarization direction and transmit linearly polarized light with a horizontal polarization direction.
[0047] Optionally, in some embodiments, the reflection axis direction of the first reflective polarizing element 13 is horizontal, and is configured to reflect linearly polarized light with a horizontal polarization direction and transmit linearly polarized light with a vertical polarization direction.
[0048] Furthermore, if Figure 2 As shown, in a modified embodiment of the present application, the first reflective polarizing element 13, the second reflective polarizing element 16, and the reciprocal polarization rotator 14 can be implemented as film materials that can be attached to flat and curved surfaces, and the non-reciprocal polarization rotator 15 can be implemented as a sheet material that can be attached to a flat surface. Based on this, the folding optical assembly further includes a lens, and the folding optical assembly further includes a first lens 21 and a second lens 22. The first reflective polarizing element 13 is combined with the reciprocal polarization rotator 14 and attached to the first lens 21, and the second reflective polarizing element 16 and the non-reciprocal polarization rotator 15 are attached to the second lens 22. The light path of this folding optical assembly is reflected between the two lenses, which increases the reflected optical path and facilitates the miniaturization of the optical system.
[0049] Furthermore, if Figure 3As shown, in another variant embodiment of the present application, the folding optical assembly further includes a third lens 23 and a fourth lens 24. The first reflective polarizing element 13 is attached to the third lens 23; the second reflective polarizing element 16, the non-reciprocal polarization rotator 15, and the reciprocal polarization rotator 14 are combined and attached to the fourth lens 24. When the second reflective polarizing element 16, the non-reciprocal polarization rotator 15, and the reciprocal polarization rotator 14 are combined, the tolerance of the polarization axis is only the combined tolerance. If the non-reciprocal polarization rotator 15 and the reciprocal polarization rotator 14 are separated, the tolerance of the polarization axis also includes the assembly tolerance. This combined approach is more conducive to reducing the optical axis tolerance, thereby improving the actual light efficiency.
[0050] For example, the folding optical component of the present application is further described below in conjunction with specific embodiments.
[0051] like Figure 1 As shown, the folding optical assembly includes an output end 11, a polarizer 12, a first reflective polarizing element 13, a reciprocal polarization rotator 14, a non-reciprocal polarization rotator 15, and a second reflective polarizing element 16, which are sequentially arranged along a first direction. The first direction is the direction in which the output end 11 emits linearly polarized light toward the human eye 17. The second direction is opposite to the first direction. The polarization direction of the first linearly polarized light 111 is horizontal, the polarization direction of the second linearly polarized light 112 is at an angle of 45° to the horizontal direction, the polarization direction of the third linearly polarized light 113 is vertical, that is, the polarization direction of the third linearly polarized light 113 is at an angle of 90° to the horizontal direction, and the polarization direction of the fourth linearly polarized light 114 is at an angle of 135° to the horizontal direction.
[0052] The linearly polarized light emitted from the output end 11 is modulated into a first linearly polarized light 111 after passing through the polarizer 12. The first linearly polarized light 111 can directly pass through the first reflective polarizing element 13. The first reflective polarizing element 13 passes through the reciprocal polarization rotator 14 along the first path 31, and its polarization direction is positively rotated by 45° to form a second linearly polarized light 112. The second linearly polarized light 112 passes through the non-reciprocal polarization rotator 15 along the first path 31, and its polarization direction is positively rotated by 45° to form a third linearly polarized light 113. The third linearly polarized light 113 continues along the first path 31 to the second reflective polarizing element 16.
[0053] The third linearly polarized light 113 is reflected by the second reflective polarizing element 16 and passes through the non-reciprocal polarization rotator 15 along the second path 32, where its polarization direction is forward rotated by 45° to form the fourth linearly polarized light 114. The fourth linearly polarized light 114 passes through the reciprocal polarization rotator 14 along the second path 32, where its polarization direction is reversely rotated by 45° to form the third linearly polarized light 113. The third linearly polarized light 113 continues to travel along the first path 31 to the first reflective polarizing element 13.
[0054] The third linearly polarized light 113 is reflected by the first reflective polarizing element 13 and passes through the reciprocal polarization rotator 14 along the third path 33, where its polarization direction is positively rotated by 45° to form the fourth linearly polarized light 114. The fourth linearly polarized light 114 passes through the non-reciprocal polarization rotator 15 along the third path 33, where its polarization direction is positively rotated by 45° to form the first polarized light. The first polarized light is transmitted along the third path 33 to the second reflective polarizing element 16, directly passes through the second reflective polarizing element 16, and reaches the human eye 17.
[0055] The linearly polarized light emitted from the transmitting end can be folded back three times between the first reflective polarizing element 13 and the second reflective polarizing element 16 without causing any light efficiency loss. Therefore, the folding optical component of the present application can greatly improve the light efficiency of the system.
[0056] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0057] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.
Claims
1. A folding optical component, characterized in that: Comprising: arranged in sequence along a first direction: a first reflective polarizing element configured to transmit the first linearly polarized light and reflect a third linearly polarized light having a polarization direction perpendicular to the polarization direction of the first linearly polarized light; a reciprocal polarization rotator having an optical axis angle of 45°, configured to rotate the polarization direction of linearly polarized light transmitted along the first direction in a forward direction by 45°, and to rotate the polarization direction of linearly polarized light transmitted along a second direction opposite to the first direction in a reverse direction by 45°; a non-reciprocal polarization rotator, wherein the optical axis angle of the non-reciprocal polarization rotator is 45°, and is used to rotate the polarization direction of linearly polarized light transmitted along the first direction or the second direction by 45° in the positive direction; as well as The second reflective polarizing element has a reflection axis direction that is the same as that of the first reflective polarizing element, and is configured to transmit the first linearly polarized light and reflect the third linearly polarized light.
2. The folding optical assembly according to claim 1, wherein: The folding optical assembly further includes a first lens and a second lens, the first reflective polarizing element is compounded with the reciprocal polarization rotator and attached to the first lens, and the second reflective polarizing element and the non-reciprocal polarization rotator are attached to the second lens.
3. The folding optical assembly according to claim 1, wherein: The folding optical assembly further includes a third lens and a fourth lens, the first reflective polarizing element is attached to the third lens; the second reflective polarizing element, the non-reciprocal polarization rotator and the reciprocal polarization rotator are combined and attached to the fourth lens.
4. The folding optical assembly according to any one of claims 1 to 3, wherein: The reflection axis direction of the first reflection polarizing element is in the vertical direction, and is used for reflecting linearly polarized light with a vertical polarization direction and transmitting linearly polarized light with a horizontal polarization direction.
5. The folding optical component according to any one of claims 1 to 3, wherein: The first reflective polarizing element is a reflective polarizing film, and the second reflective polarizing element is a reflective polarizing film.
6. The folding optical component according to any one of claims 1 to 3, wherein: The reciprocal polarization rotator is a half-wave plate.
7. The folding optical assembly according to any one of claims 1 to 3, wherein: The non-reciprocal polarization rotator is a Faraday rotator.
8. An optical module, characterized in that: include: an output component, the output component being configured to emit a first linearly polarized light; and The folding optical component according to any one of claims 1 to 7, wherein the folding optical component is arranged on the light-emitting side of the output component along the first direction.
9. The optical module according to claim 8, wherein: The output component includes an output end and a polarizer sequentially arranged along the first direction, and the polarizer is used to modulate the linearly polarized light emitted by the output end into a first linearly polarized light.
10. The optical module according to claim 9, wherein: The polarizer is an iodine-based polarizer.