Goertek Optical Technology Patent | Optical module and head mounted display

Patent: Optical module and head mounted display

Publication Number: 20250306388

Publication Date: 2025-10-02

Assignee: Goertek Optical Technology

Abstract

Embodiments of the present disclosure provide an optical module and a head mounted display; wherein, the optical module comprises a first lens, a second lens, and a third lens provided sequentially, a beam splitter provided between the second lens and the first lens, and a first phase retarder and a polarization reflection film provided on either side of the third lens. The first lens is configured for transmitting incident light, and an optical path difference between an optical path at a 1.0 aperture of the first lens and a central optical path of the first lens is 0.25˜0.5 times of the central optical path.

Claims

1. An optical module, comprising:a first lens, a second lens, and a third lens provided sequentially,a beam splitter, which is provided between the second lens and the first lens, anda first phase retarder and a polarization reflection film, provided on a side of the third lens,wherein, the first lens is configured for transmitting incident light, andan optical path difference between an optical path at a 1.0 aperture of the first lens and a central optical path of the first lens is 0.25˜0.5 times of the central optical path.

2. The optical module according to claim 1, wherein the optical path difference between the optical path at the 1.0 aperture of the first lens and the central optical path of the first lens is −1.6 to −1.

3. The optical module according to claim 1, wherein the optical path difference between the optical path at the 1.0 aperture of the first lens and the central optical path of the first lens is −1.58 to −1.2.

4. The optical module according to claim 1, wherein an optical path difference between an optical path at a 0.7 to 0.9 aperture of the first lens and the central optical path of the first lens is −1.5 to −0.05.

5. The optical module according to claim 1, wherein an optical path difference between an optical path at a 0.7 aperture of the first lens and the central optical path of the first lens is −1 to −0.05;an optical path difference between an optical path at a 0.8 aperture of the first lens and the central optical path of the first lens is −1.2 to −0.3;an optical path difference between an optical path at a 0.9 aperture of the first lens and the central optical path of the first lens is −1.5 to −0.5.

6. The optical module according to claim 1, wherein central thickness T₁ of the first lens is 3 mm1<6 mm;the first lens comprises a first surface and a second surface, both of which are aspherical surfaces.

7. The optical module according to claim 1, wherein the first lens has a focal power φ₁, which is positive and satisfies: 0<φ₁<0.01.

8. The optical module according to claim 6, wherein the second lens comprises a third surface and a fourth surface, the third surface is adjacent to the second surface and is an aspherical surface, and the fourth surface is a flat surface or an aspherical surface;the third lens comprises a fifth surface and a sixth surface, both of which are aspherical surfaces, and the fifth surface is adjacent to the fourth surface.

9. The optical module according to claim 8, wherein the first phase retarder and the polarization reflection film are sequentially provided between the fourth surface and the fifth surface.

10. The optical module according to claim 9, wherein the optical module further comprises a polarizing film, which is provided between the fifth surface and the polarization reflection film.

11. The optical module according to claim 10, wherein the polarization reflection film and the polarizing film are stacked to form a film layer structure, which is attached to the fifth surface;the first phase retarder is attached to the fourth surface.

12. The optical module according to claim 1, wherein the beam splitter has a reflectivity of 47% to 53%.

13. The optical module according to claim 1, wherein the first lens, the second lens, and the third lens have a refractive index n: 1.4the first lens, the second lens, and the third lens have an Abbe number v: 20

14. The optical module according to claim 1, wherein the optical module further comprises a display, which is configured for emitting circularly polarized light or linearly polarized light;when the display is adapted to emits the linearly polarized light, a second phase retarder is provided between the display and the first lens, and is configured for converting the linearly polarized light into circularly polarized light.

15. The optical module according to claim 14, wherein the display has a size of 1 inch to 2.1 inches.

16. A head mounted display, comprising:a housing; andan optical module according to claim 1.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present disclosure is a National Stage of International Application No. PCT/CN2022/101436, filed on Jun. 27, 2022, which claims priority to a Chinese patent application No. 202210560045.9 filed with the CNIPA on May 19, 2022, both of which are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

Embodiments of the present disclosure relate to the technical field of near-eye display imaging, and particularly to an optical module and a head mounted display.

BACKGROUND

In recent years, augmented reality (AR) and virtual reality (VR) technologies have been applied and rapidly developed in smart wearable devices, for example. Core components of both AR and VR technologies are optical modules. The quality of the display effect of the optical module directly determines the quality of the smart wearable device.

In the prior art, to achieve a miniaturized and lightweight virtual reality imaging system, it is necessary to use smaller displays. However, under the same optical specifications (such as field of view angle, imaging quality, etc.), the smaller the size of the display, the more stringent the requirements become for the optical module. Most existing folded optical path solutions include two lenses. For small screens, the optical module must provide a large focal power and a significant bending angle for the peripheral field of view, which makes it difficult to achieve simultaneous clear imaging in both the central and peripheral fields of view. This also leads to a problem where field curvature is difficult to eliminate, thereby impacting the imaging effect.

SUMMARY

An objective of the present disclosure is to provide new technical solutions for an optical module and a head mounted display.

In a first aspect, the present disclosure provides an optical module, which includes a first lens, a second lens, and a third lens provided sequentially;

the first lens is configured for transmitting incident light;

a beam splitter is provided between the second lens and the first lens;a first phase retarder and a polarization reflection film are provided on either side of the third lens;an optical path difference between an optical path at 1.0 aperture of the first lens and a central optical path of the first lens is 0.25˜0.5 times of the central optical path.

Optionally, the optical path difference between the optical path at 1.0 aperture of the first lens and the central optical path of the first lens is −1.6 to −1.

Optionally, the optical path difference between the optical path at 1.0 aperture of the first lens and the central optical path of the first lens is −1.58 to −1.2.

Optionally, an optical path difference between an optical path at 0.7 to 0.9 aperture of the first lens and the central optical path of the first lens is −1.5 to −0.05.

Optionally, an optical path difference between an optical path at 0.7 aperture of the first lens and the central optical path of the first lens is −1 to −0.05;

an optical path difference between an optical path at 0.8 aperture of the first lens and the central optical path of the first lens is −1.2 to −0.3;

an optical path difference between an optical path at 0.9 aperture of the first lens and the central optical path of the first lens is −1.5 to −0.5.

Optionally, central thickness T₁ of the first lens is 3 mm1<6 mm;

the first lens includes a first surface and a second surface, both of which are aspherical surfaces.

Optionally, the first lens has a focal power φ₁, which is positive and satisfies: 0<φ₁<0.01.

Optionally, the second lens includes a third surface and a fourth surface, the third surface is adjacent to the second surface and is an aspherical surface, and the fourth surface is a flat surface or an aspherical surface;

the third lens includes a fifth surface and a sixth surface, both of which are aspherical surfaces, and the fifth surface is adjacent to the fourth surface.

Optionally, the first phase retarder and the polarization reflection film are sequentially provided between the fourth surface and the fifth surface.

Optionally, the optical module further includes a polarizing film, which is provided between the fifth surface and the polarization reflection film.

Optionally, the polarization reflection film and the polarizing film are stacked to form a film layer structure and are attached to the fifth surface;

the first phase retarder is attached to the fourth surface.

Optionally, the beam splitter has a reflectivity of 47% to 53%.

Optionally, the first lens, the second lens, and the third lens have a refractive index n: 1.4the first lens, the second lens, and the third lens have an Abbe number v: 20

Optionally, the optical module further includes a display, which is configured for emitting circularly polarized light or linearly polarized light;

when the display emits the linearly polarized light, a second phase retarder is provided between the display and the first lens, and is configured for converting the linearly polarized light into circularly polarized light.

Optionally, the display has a size of 1 inch to 2.1 inches.

In a second aspect, the present disclosure provides a head mounted display, which includes:

a housing; and

the above-mentioned optical module.

According to the embodiments of the present disclosure, by adopting a reasonable combination of three lenses and effectively controlling the ratio of the optical path difference between the peripheral and central optical paths of the optical lens proximate to the incident light, i.e., the first lens, to the central optical path, it is possible to achieve simultaneous clear imaging in both the central and peripheral fields of view at the same image plane position. This helps to eliminate field curvature, resulting in an optical module with low field curvature. Consequently, this significantly enhances the imaging quality, thereby providing users with a better visual experience.

Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in the description and constitute a part of the description, illustrate embodiments of the present disclosure and, together with the description thereof, serve to explain the principles of the present disclosure.

FIG. 1 is a first structural schematic diagram of an optical module according to an embodiment of the present disclosure;

FIG. 2 is a variation diagram of optical path differences between optical paths at different apertures and a central optical path of a first lens in the optical module shown in FIG. 1;

FIG. 3 is a schematic diagram showing the film layer structures separately attached to a fourth surface of a second lens and a sixth surface of a third lens in the optical module according to an embodiment of the present disclosure;

FIG. 4 is a second structural schematic diagram of the optical module according to an embodiment of the present disclosure;

FIG. 5 is a variation diagram of optical path differences between optical paths at different apertures and a central optical path of a first lens in the optical module shown in FIG. 4;

FIG. 6 is a schematic diagram of a point array of the optical module shown in FIGS. 1 and 4;

FIG. 7 is an MTF graph of the optical module shown in FIGS. 1 and 4;

FIG. 8 is a field curvature distortion diagram of the optical module shown in FIGS. 1 and 4;

FIG. 9 is a lateral chromatic distortion diagram of the optical module shown in FIGS. 1 and 4;

FIG. 10 is a third structural schematic diagram of the optical module according to an embodiment of the present disclosure;

FIG. 11 is a variation diagram of optical path differences between optical paths at different apertures and a central optical path of a first lens in the optical module shown in FIG. 10;

FIG. 12 is a schematic diagram of a point array of the optical module shown in FIG. 10;

FIG. 13 is an MTF curve diagram of the optical module shown in FIG. 10;

FIG. 14 is a field curvature distortion diagram of the optical module shown in FIG. 10;

FIG. 15 is a lateral chromatic aberration diagram of the optical module shown in FIG. 10;

FIG. 16 is a fourth structural schematic diagram of the optical module according to an embodiment of the present disclosure;

FIG. 17 is a variation diagram of optical path differences between optical paths at different apertures and a central optical path of a first lens in the optical module shown in FIG. 16;

FIG. 18 is a schematic diagram of a point array of the optical module shown in FIG. 16;

FIG. 19 is an MTF curve diagram of the optical module shown in FIG. 16;

FIG. 20 is a field curvature distortion diagram of the optical module shown in FIG. 16;

FIG. 21 is a lateral chromatic aberration diagram of the optical module shown in FIG. 16;

FIG. 22 is a first partial structural schematic diagram of the first lens in the optical module according to an embodiment of the present disclosure;

FIG. 23 is a second partial structural schematic diagram of the first lens in the optical module according to an embodiment of the present disclosure.

DESCRIPTION OF REFERENCE SIGNS

10. first lens; 11. first surface; 12. second surface; 20. second lens; 21. third surface; 22. fourth surface; 30. third lens; 31. fifth surface; 32. sixth surface; 40. third anti-reflective film; 50. first phase retarder; 60. polarizing film; 70. polarization reflection film; 80. display; 81. protective glass; 90. beam splitter; 01. human eye.

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