CN-121995565-A - Light guide device and near-to-eye display

Abstract

A light guiding device includes a light guiding plate, a diffraction grating and a phase delay element. The diffraction grating is disposed on the first surface of the light guide plate. When the light beam enters the diffraction grating, the diffraction grating is used for generating a plurality of diffracted light beams. The diffracted beams include a main diffracted beam that propagates within the light guide plate. The phase delay element is disposed on the transmission path of the main diffraction beam. The main diffracted beam has a first polarization state before entering the phase delay element, and the main diffracted beam has a second polarization state when exiting the phase delay element, the first polarization state being different from the second polarization state. A near-eye display is also provided. The light guide device and the near-eye display provided by the invention have low energy consumption and good optical performance.

Inventors

• LUO YIJIAN
• WANG WENJUN

Assignees

• 中强光电股份有限公司

Dates

Publication Date

20260508

Application Date

20241107

Claims (20)

1. 1. A light guide device for guiding a light beam, the light guide device comprising a light guide plate, a diffraction grating, and a phase delay element, wherein: The diffraction grating is disposed on the first surface of the light guide plate, wherein when the light beam is incident on the diffraction grating, the diffraction grating is used for generating a plurality of diffracted light beams, the plurality of diffracted light beams comprises a main diffracted light beam, the main diffracted light beam is transmitted in the light guide plate, and The phase delay element is configured on a transmission path of the main diffraction light beam, the main diffraction light beam has a first polarization state before entering the phase delay element, the main diffraction light beam has a second polarization state when leaving the phase delay element, and the first polarization state is different from the second polarization state.
2. 2. The light guide of claim 1, wherein a portion of the main diffracted beam passes through the phase delay element once.
3. 3. A light guide as recited in claim 1, wherein the first polarization state is perpendicular to the second polarization state.
4. 4. The light guide device of claim 1, wherein the diffraction grating is a reflective diffraction grating.
5. 5. The light guide device of claim 4, further comprising a first mirror disposed on the first surface of the light guide plate, wherein the diffraction grating is located between the first mirror and the light guide plate.
6. 6. A light guide as recited in claim 5, further comprising a second reflector disposed on a second surface of the light guide plate, wherein the light guide plate is positioned between the first reflector and the second reflector.
7. 7. The light guide of claim 4, wherein the light beam passes through the phase delay element before entering the diffraction grating.
8. 8. The light guide device of claim 7, further comprising a first mirror disposed on the first surface of the light guide plate, wherein the diffraction grating is located between the first mirror and the light guide plate.
9. 9. A light guide as recited in claim 7, wherein the light beam has a polarization state, and the phase delay element is configured to convert the polarization state to the first polarization state.
10. 10. The light guide device of claim 1, wherein the diffraction grating is a transmissive grating.
11. 11. A light guide as recited in claim 10, further comprising a first reflector disposed on a second surface of the light guide plate, the first surface being opposite the second surface.
12. 12. The light guide device of claim 11, further comprising a second mirror disposed on the first surface of the light guide plate, wherein the diffraction grating is located between the second mirror and the light guide plate.
13. 13. The light guide device of claim 10, wherein the plurality of diffracted light beams further comprises a sub-diffracted light beam, and the phase delay element is disposed on a transmission path of the sub-diffracted light beam.
14. 14. A light guide as recited in claim 13, further comprising a first mirror, wherein the phase delay element is located between the first mirror and the light guide plate.
15. 15. A light guide device as claimed in claim 10, wherein the phase delay element comprises a first phase delay layer and a second phase delay layer laminated.
16. 16. A light guide as recited in claim 15, further comprising a first mirror disposed on the first surface of the light guide plate, wherein the first phase retardation layer and the second phase retardation layer are located between the first surface of the light guide plate and the first mirror.
17. 17. A light guide as recited in claim 16, wherein the first phase retardation layer is located between the first surface of the light guide plate and the second phase retardation layer.
18. 18. A light guide as recited in claim 17, wherein the first phase retardation layer is disposed on the first surface of the light guide plate.
19. 19. A light guide as recited in claim 17, wherein the second phase retardation layer is disposed on the first mirror.
20. 20. A light guide device as recited in claim 1, wherein the phase delay element is parallel to the first surface of the light guide plate.

Description

Light guide device and near-to-eye display Technical Field The present invention relates to an optical device, and more particularly, to a light guide device and a near-to-eye display. Background The diffractive waveguide (DIFFRACTIVE WAVEGUIDE) may be thinner than the geometric waveguide. The diffractive waveguides currently have Surface relief gratings (Surface RELIEF GRATING, SRG), volume holographic gratings (Volume holographic grating, VHG) and polarizing volume gratings (polarization volume grating, PVG). Surface Relief Gratings (SRGs) offer advantages over other diffraction gratings in terms of efficiency and design freedom. Ideally, it is expected that diffracted light generated via the incoupling grating can be transmitted completely within the waveguide to the waveguide exit by total reflection. However, the coupling-in grating generally has a certain area, so that the diffracted light beam generated by the coupling-in grating is totally reflected in the waveguide and then is incident into the coupling-in grating again, and the diffraction phenomenon occurs again, resulting in unexpected light leakage. The background section is only for the purpose of aiding in the understanding of the present invention and thus the disclosure of the background section may include some techniques that do not form part of the knowledge of one of ordinary skill in the art. The disclosure of the "background" section is not intended to represent the subject matter or problem underlying one or more embodiments of the present invention, as it would be known or appreciated by one of ordinary skill in the art prior to the application of the present invention. Disclosure of Invention The invention provides a light guide device which has low energy consumption and good optical performance. Other objects and advantages of the present invention will be further appreciated from the technical features disclosed in the present invention. To achieve one or a part or all of the above or other objects, a light guiding device according to an embodiment of the present invention is used for guiding a light beam, and includes a light guiding plate, a diffraction grating and a phase delay element. The diffraction grating is configured on the first surface of the light guide plate, wherein when the light beam enters the diffraction grating, the diffraction grating is used for generating a plurality of diffraction light beams, and the diffraction light beams comprise main diffraction light beams, and the main diffraction light beams are transmitted in the light guide plate. The phase delay element is configured on the transmission path of the main diffraction light beam, the main diffraction light beam has a first polarization state before entering the phase delay element, and the main diffraction light beam has a second polarization state when leaving the phase delay element, and the first polarization state is different from the second polarization state. According to another embodiment of the present invention, a near-eye display is provided, which includes an image light source and a light guiding device. The image light source is used for emitting light beams. The light guide device is arranged on the transmission path of the light beam, is used for guiding the light beam, and comprises a light guide plate, a diffraction grating and a phase delay element. The diffraction grating is configured on the first surface of the light guide plate, wherein when the light beam enters the diffraction grating, the diffraction grating is used for generating a plurality of diffraction light beams, and the diffraction light beams comprise main diffraction light beams, and the main diffraction light beams are transmitted in the light guide plate. The phase delay element is configured on the transmission path of the main diffraction light beam, the main diffraction light beam has a first polarization state before entering the phase delay element, and the main diffraction light beam has a second polarization state when leaving the phase delay element, and the first polarization state is different from the second polarization state. Based on the above, the light guiding device and the near-to-eye display provided by the embodiments of the present invention have at least one of the following features and advantages of (1) avoiding the energy loss caused by the diffraction phenomenon of the diffracted light beam due to the re-incidence of the coupling-in grating by controlling the polarization state of the diffracted light beam, (2) enhancing the intensity of the light transmitted in the light guiding plate by reflecting the light exiting the light guiding plate back to the light guiding plate by using the reflecting mirror, and reducing the energy loss, (3) recovering the 0-order diffracted light beam, and enhancing the intensity of the light transmitted in the light guiding plate. In order to make the above features and advantages of the present inventi