Turn-back type optical assembly and optical module
By using a combination of reflective polarizer film and rotator in a head-mounted display device, instead of the spectroscopic film, multiple folding paths are formed, which solves the problem of low light efficiency in the prior art, and achieves more efficient optical path folding and light efficiency improvement.
Patent Information
- Application Number
- CN202411318896.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-20
- Publication Date
- 2024-12-13
AI Technical Summary
The foldback optical system of existing head-mounted display devices has a low light effect, resulting in light loss, which in turn reduces the overall light efficiency.
Reflective polarization film is used instead of the spectroscopic film, and a reciprocating polarization rotator and a non-reciprocating polarization rotator are added to the optical path to form multiple folding paths to improve the light efficiency.
By abolishing the spectroscopic film and using the combination of reflective polarization film and rotator, the folding of the optical path is achieved without causing light efficiency loss, greatly improving the light efficiency of the folding optical component.
Smart Images
Figure CN119126386A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of head mounted display devices, and in particular to a folding optical component and an optical module. Background Art
[0002] In order to reduce the thickness of the module, the existing head-mounted display devices usually use a folding optical system composed of a beam splitter film (BS film) and a reflective polarizing film (RP film) to fold the light path of the system, so that the light is reflected between the beam splitter film and the reflective polarizing film and finally enters the human eye.
[0003] However, since the beam splitter film can only transmit half of the polarized light and reflect the other half of the polarized light, the light emitted from the transmitting end is lost, resulting in low light efficiency of the reflective optical system. Summary of the invention
[0004] Based on this, it is necessary to provide a folding optical component and an 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, wherein the first reflective polarizing element is used 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, wherein the optical axis angle of the reciprocal polarization rotator is 45°, and is used to rotate the polarization direction of the linear polarized light transmitted along the first direction forward by 45°, and to rotate the polarization direction of the linear polarized light transmitted along a second direction opposite to the first direction reversely 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 positively rotate the polarization direction of the linearly polarized light transmitted along the first direction or the second 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 used for transmitting the first linearly polarized light and reflecting the third linearly polarized light.
[0010] In one of the embodiments, 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 component 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 composited and attached to the fourth lens.
[0014] In one embodiment, the reflection axis direction of the first reflection polarization element is in a vertical direction, and is used to reflect linear polarized light with a vertical polarization direction and transmit linear 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 of the embodiments, 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.
[0022] In one embodiment, the polarizer is an iodine-based polarizer.
[0023] The above-mentioned folding optical component eliminates the beam splitting film (BS film), replaces the beam splitting 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 diagram of the structure of an optical module provided in one embodiment of the present application;
[0025] Figure 2 A structural schematic 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] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by 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 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.
[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.
[0031] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection, an optical connection, or a polarization connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0032] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in 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 a central 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 a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.
[0034] Based on the problem of low light efficiency in existing head-mounted display devices, the present application provides a reciprocating optical component and an optical module. The optical module includes an output component and a reciprocating optical component, the reciprocating 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 reciprocating optical component cancels the beam splitter film (BS film), replaces the beam splitter film with a reflective polarizing film (RP film), and adds a reciprocal polarization rotator and a non-reciprocal polarization rotator, which greatly improves the light efficiency of the reciprocating optical component while realizing the light path reversal.
[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 linear polarized light 111 and reflect the third linear polarized light 113 whose polarization direction is perpendicular to the polarization direction of the first linear polarized light 111; the reciprocal polarization rotator 14 has an optical axis angle of 45°, and is used to rotate the polarization direction of the linear polarized light transmitted along the first direction by 45° in the positive direction, so that the linear polarized light transmitted along the first direction is not polarized in the positive direction. The polarization direction of the linear 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°, which is used to rotate the polarization direction of the linear polarized light transmitted along the first direction or the second direction forward 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, which is used to transmit the linear polarized light perpendicular to the polarization direction of the first linear polarized light 111, and reflect the third linear polarized light 113 whose polarization direction is perpendicular to the polarization direction of the first linear 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 on 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 positively rotated by 45° twice, that is, the polarization direction of the linearly polarized light is rotated by 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 positively rotated by 45° and then reversely rotated by 45°. , 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 polarization element 13 and the second reflective polarization element 16 is the same as the polarization direction of the linear polarized light that can be transmitted by the first reflective polarization element 13, and the fold-back optical component utilizes the reciprocal polarization rotator 14 and the non-reciprocal polarization rotator 15 to form three fold-back paths between the first reflective polarization element 13 and the second reflective polarization 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 the first linear polarized light 111 emitted by the output component passes through the first polarization reflection element, it passes through the reciprocal polarization rotator 14 and the non-reciprocal polarization rotator 15 in sequence along the first path 31, and the polarization direction is rotated by 90°, and is reflected by the second polarization reflection element. It passes through the non-reciprocal polarization rotator 15 and the reciprocal polarization rotator 14 in sequence along the second path 32, and the polarization direction remains unchanged, and is reflected by the first polarization reflection element. It passes through the reciprocal polarization rotator 14 and the non-reciprocal polarization rotator 15 in sequence along the third path 33, and the polarization direction is rotated by 90°, and passes through the second polarization reflection element to reach the human eye 17, thereby completing the return of the optical path.
[0038] It is worth noting that the first direction in the present 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 The left-to-right direction in .
[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 the 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 of the embodiments, 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 linear polarized light parallel to the arrangement direction of 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 linear polarized light in one polarization direction and transmit linear polarized light perpendicular to the polarization direction. The reflective polarizing film can be formed by stacking two media with different characteristics multiple times, and is formed by co-extrusion, stretching and other processes. One medium in the reflective polarizing film can change the refractive index in the stretching direction by stretching, so that the stretched medium exhibits birefringence characteristics, and the refractive index of the other medium remains unchanged after stretching, so that the linear polarized light in the stretching direction is reflected and the linear polarized light perpendicular to the stretching direction is transmitted.
[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 the rotation angle of the polarized light is the same but the rotation direction is opposite after the linear polarized light passes through the reciprocal polarization rotator 14 along the first direction and the reciprocal polarization rotator 14 along the second direction, the reciprocal polarization rotator 14 can be implemented as a half-wave plate. The half-wave plate is a birefringent crystal. When the linear polarized light passes through, the refractive index of the ordinary light and the extraordinary light are different, and the phase difference therebetween is an odd multiple of π. When the angle between the optical axis of the linear polarized light and the optical axis of the half-wave plate is α, after the linear polarized light passes through the half-wave plate, the polarization direction of the linear polarized light rotates by 2α, so that the linear polarized light rotates 45° after passing through the half-wave plate.
[0045] Optionally, in some embodiments, based on the characteristic that the rotation angle and rotation direction of the polarized light are the same after the linear polarized light passes through the non-reciprocal polarization rotator 15 along the first direction and the reciprocal polarization rotator 14 along the second direction, the non-reciprocal polarization rotator 15 can be implemented as a Faraday rotator. The Faraday rotator utilizes the Faraday effect. When a magnetic field is applied to a transparent medium, due to the electromagnetic properties of light, it is easy to rotate in one direction and not easy to rotate in another direction. By controlling the direction and propagation distance of the magnetic field, the rotation angle of the linear 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 in a vertical direction, and is used to reflect linear polarized light with a vertical polarization direction and transmit linear 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 used to reflect linear polarized light with a horizontal polarization direction and transmit linear 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 a film material, which can be attached to a plane and a curved surface, and the non-reciprocal polarization rotator 15 can be implemented as a sheet material, which can be attached to a plane. Based on this, the reciprocal optical component further includes a lens, and the reciprocal optical component further includes a first lens 21 and a second lens 22, the first reflective polarizing element 13 is compounded 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 optical path of the reciprocal optical component is reflected between the two lenses, which increases the reflected optical path and is conducive to the miniaturization of the optical system.
[0049] Furthermore, if Figure 3As shown, in another variant embodiment of the present application, the folding optical component 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 compounded and attached to the fourth lens 24. The second reflective polarizing element 16, the non-reciprocal polarization rotator 15 and the reciprocal polarization rotator 14 are compounded together, and the tolerance of the polarization axis is only the compound 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 compounding method is more conducive to reducing the optical axis tolerance, thereby facilitating improving the actual light effect.
[0050] Exemplarily, 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 component 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 to the human eye 17, and the second direction is opposite to the first direction. The polarization direction of the first linear polarized light 111 is a horizontal direction, the angle between the polarization direction of the second linear polarized light 112 and the horizontal direction is 45°, the polarization direction of the third linear polarized light 113 is a vertical direction, that is, the angle between the polarization direction of the third linear polarized light 113 and the horizontal direction is 90°, and the angle between the polarization direction of the fourth linear polarized light 114 and the horizontal direction is 135°.
[0052] The linear polarized light emitted from the output end 11 is modulated into a first linear polarized light 111 after passing through the polarizer 12. The first linear 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 the polarization direction is positively rotated by 45° to form a second linear polarized light 112. The second linear polarized light 112 passes through the non-reciprocal polarization rotator 15 along the first path 31, and the polarization direction is positively rotated by 45° to form a third linear polarized light 113. The third linear polarized light 113 continues to be transmitted to the second reflective polarizing element 16 along the first path 31.
[0053] The third linear polarized light 113 is reflected by the second reflective polarizing element 16, passes through the non-reciprocal polarization rotator 15 along the second path 32, and the polarization direction is positively rotated by 45° to form the fourth linear polarized light 114; the fourth linear polarized light 114 passes through the reciprocal polarization rotator 14 along the second path 32, and the polarization direction is reversely rotated by 45° to form the third linear polarized light 113; the third linear polarized light 113 continues to be transmitted to the first reflective polarizing element 13 along the first path 31;
[0054] The third linear polarized light 113 is reflected by the first reflective polarizing element 13, passes through the reciprocal polarization rotator 14 along the third path 33, and the polarization direction is positively rotated by 45° to form the fourth linear polarized light 114; the fourth linear polarized light 114 passes through the non-reciprocal polarization rotator 15 along the third path 33, and the polarization direction is positively rotated by 45° to form the first polarized light; the first polarized light is transmitted to the second reflective polarizing element 16 along the third path 33, and directly passes through the second reflective polarizing element 16 to reach the human eye 17.
[0055] The linearly polarized light emitted from the transmitting end can be folded back three times between the first reflective polarization element 13 and the second reflective polarization 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-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A folding optical component, characterized in that: The method comprises the following steps arranged in sequence along a first direction: a first reflective polarizing element, wherein the first reflective polarizing element is used 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, wherein the optical axis angle of the reciprocal polarization rotator is 45°, and is used to rotate the polarization direction of the linear polarized light transmitted along the first direction forward by 45°, and to rotate the polarization direction of the linear polarized light transmitted along a second direction opposite to the first direction reversely 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 the 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 used for transmitting the first linearly polarized light and reflecting the third linearly polarized light.
2. The folding optical component according to claim 1, characterized in that: 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.
3. The folding optical component according to claim 1, characterized in that: The folding optical component 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 composited and attached to the fourth lens.
4. The folding optical component according to any one of claims 1 to 3, characterized in that: The reflection axis direction of the first reflection polarization element is in the vertical direction, and is used for reflecting linear polarized light with a polarization direction in the vertical direction and transmitting linear polarized light with a polarization direction in the horizontal direction.
5. The folding optical component according to any one of claims 1 to 3, characterized in that: 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, characterized in that: The reciprocal polarization rotator is a half-wave plate.
7. The folding optical component according to any one of claims 1 to 3, characterized in that: The non-reciprocal polarization rotator is a Faraday rotator.
8. An optical module, characterized in that: include: An output component, the output component is used to emit a first linearly polarized light; and The folding optical component as described in 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, characterized in that: 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, characterized in that: The polarizer is an iodine-based polarizer.