CN118131388A - AR display device adopting holographic optical waveguide - Google Patents

Abstract

The application provides a holographic optical waveguide AR display device, which particularly enables more effective image light to be transmitted in an optical waveguide through diffraction modulation of a coupling-in coupling-out grating and polarization modulation conversion of a polarization state regulating device on transmission light, does not generate other parasitic light influence, and finally couples more effective light out of the optical waveguide to enter human eyes for imaging.

Description

AR display device adopting holographic optical waveguide

Technical Field

The embodiments of the present application belong to the technical field of optical waveguide AR display, and in particular, relate to an AR display device using holographic optical waveguides.

Background

The optical waveguide display technology is an important development direction in the field of Augmented Reality (AR), and is a new technology for superimposing real world information and virtual image information, thereby providing a user with an "enhanced" display effect. The diffractive optical waveguide display mainly comprises a surface relief grating and a holographic body grating. The optical waveguide display scheme of the surface relief grating is that a corresponding periodic micro-nano structure is generated on the surface of a substrate through a semiconductor processing technology, so that diffraction regulation and control of incident light are realized, the preparation cost of the scheme is relatively high, and the diffraction efficiency of an optical waveguide display system is generally low; in the volume holographic optical waveguide display scheme, two beams of coherent laser are used for carrying out holographic exposure on a photosensitive material to form a refractive index difference, namely a holographic grating is generated, and the scheme has the advantages of high diffraction efficiency, low cost, easiness in mass production and the like.

However, the mainstream of the present application is a holographic bulk grating optical waveguide scheme based on polymer dispersed liquid crystal, which generally has higher diffraction efficiency only for P polarized light, but lower diffraction efficiency for S polarized light, so that the light energy utilization rate is lower when the image sources of unpolarized light are collocated. Therefore, it is necessary to develop an AR device that can adapt to different polarized light sources and can effectively improve the display efficiency of the optical waveguide.

Disclosure of Invention

In order to solve or alleviate the problems in the prior art. Accordingly, an embodiment of the present application provides an AR display device employing a holographic optical waveguide, the device comprising a micro display system, a first optical waveguide, and a second optical waveguide;

the first optical waveguide is provided with a first coupling-in grating and a first coupling-out grating;

the second optical waveguide is provided with a second coupling-in grating and a second coupling-out grating;

the first optical waveguide is arranged on the upper surface of the second optical waveguide, the region of the first coupling-in grating arranged on the first optical waveguide corresponds to the region of the second coupling-in grating arranged on the second optical waveguide, and the region of the first coupling-out grating arranged on the first optical waveguide corresponds to the region of the second coupling-out grating arranged on the second optical waveguide;

A first polarization state regulating device and a second polarization state regulating device are arranged between the first optical waveguide and the second optical waveguide, the first polarization state regulating device is arranged in a region corresponding to the first coupling-in grating or the second coupling-in grating, the second polarization state regulating device is arranged in a region corresponding to the first coupling-out grating or the second coupling-out grating, and the first polarization state regulating device and the second polarization state regulating device are respectively used for regulating and controlling the light polarization state;

The micro display system is used for emitting collimated light, and the collimated light transmitted by the first coupling-in grating is incident to the first polarization state regulating device for polarization state regulation after passing through the first optical waveguide, then is incident to the second polarization state regulating device for polarization state regulation after passing through the second coupling-in grating, the second optical waveguide and the second coupling-out grating, and enters the human eye for imaging after passing through the first optical waveguide and the first coupling-out grating.

As a preferred embodiment of the present application, the micro display system includes: a micro display and a collimating lens;

and emitting image light through the micro display, wherein the image light is processed by the collimating lens to obtain collimated light.

As a preferred embodiment of the present application, the image light is a polarized light source or an unpolarized light source.

As a preferred embodiment of the present application, the first coupling-in grating, the first coupling-out grating, the second coupling-in grating and the second coupling-out grating are all reflective gratings, transmissive gratings or a combination of reflective gratings and transmissive gratings.

As a preferred embodiment of the present application, a first turning grating is disposed between the first in-coupling grating and the first out-coupling grating region;

and a second turning grating is arranged between the second coupling-in grating and the second coupling-out grating region.

As a preferred embodiment of the present application, the grating periods of the first in-coupling grating and the first out-coupling grating are the same;

The periods of the second in-coupling grating and the second out-coupling grating are the same.

As a preferred embodiment of the present application, the first polarization state adjusting device and the second polarization state adjusting device are all electrically controlled liquid crystal wave plates; or alternatively, the first and second heat exchangers may be,

The first polarization state regulating device is an electric control liquid crystal wave plate, and the second polarization state regulating device is a half wave plate.

Compared with the prior art, the embodiment of the application provides the holographic optical waveguide AR display device, and particularly, more effective image light can be transmitted in the optical waveguide through diffraction modulation of the coupling-in coupling-out grating and polarization modulation conversion of the polarization state regulating device on transmission light, other parasitic light influence is not generated, and finally more effective light is coupled out of the optical waveguide to enter human eyes for imaging.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. Some specific embodiments of the application will be described in detail hereinafter by way of example and not by way of limitation with reference to the accompanying drawings. The same reference numbers in the drawings denote the same or similar parts or portions, and it will be understood by those skilled in the art that the drawings are not necessarily drawn to scale, in which:

FIG. 1 is a schematic diagram of a display device employing holographic optical waveguides AR according to the present application;

FIG. 2 is a schematic diagram of an AR display device according to embodiment 1 of the present application;

fig. 3 is a schematic structural diagram of a display device using holographic optical waveguide AR according to embodiment 2 of the present application.

Detailed Description

In order to enable those skilled in the art to better understand the present application, the following description will make clear and complete descriptions of the technical solutions according to the embodiments of the present application with reference to the accompanying drawings. It will be apparent that the described embodiments are merely some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.

As shown in fig. 1, an embodiment of the present application provides a display device employing a holographic optical waveguide AR, the device including a micro display system 3, a first optical waveguide 1 and a second optical waveguide 2;

The first optical waveguide 1 is provided with a first coupling-in grating 6 and a first coupling-out grating 7;

The second optical waveguide 2 is provided with a second in-coupling grating 8 and a second out-coupling grating 9;

The first optical waveguide 1 is arranged on the upper surface of the second optical waveguide 2, the area where the first coupling-in grating 6 is arranged on the first optical waveguide 1 corresponds to the area where the second coupling-in grating 8 is arranged on the second optical waveguide 2, and the area where the first coupling-out grating 7 is arranged on the first optical waveguide 1 corresponds to the area where the second coupling-out grating 9 is arranged on the second optical waveguide 2;

A first polarization state regulating device 4 and a second polarization state regulating device 5 are arranged between the first optical waveguide 1 and the second optical waveguide 2, the first polarization state regulating device 4 is arranged in a region corresponding to the first coupling-in grating 6 or the second coupling-in grating 8, the second polarization state regulating device 5 is arranged in a region corresponding to the first coupling-out grating 7 or the second coupling-out grating 9, and the first polarization state regulating device 4 and the second polarization state regulating device 5 are respectively used for regulating and controlling the light polarization state;

the micro display system 3 is configured to emit collimated light, and the collimated light transmitted through the first coupling-in grating 6 is incident on the first polarization state adjusting device 4 after passing through the first optical waveguide 1, then is processed by the second coupling-in grating 8, the second optical waveguide 2 and the second coupling-out grating 9, is incident on the second polarization state adjusting device 5, is processed by the first optical waveguide 1 and the first coupling-out grating 7, and enters the human eye 10 to form an image.

In the embodiment of the application, the first polarization state regulating device 4 and the second polarization state regulating device 5 are all electric control liquid crystal wave plates; or, the first polarization state regulating device 4 is an electric control liquid crystal wave plate, and the second polarization state regulating device 5 is a half wave plate.

It should be noted that, in addition, the second polarization state adjusting device 5 corresponding to the coupling-out region may be replaced by a conventional half-wave plate, without using an electronically controlled liquid crystal wave plate, but the first polarization state adjusting device 4 cannot be replaced by a conventional half-wave plate.

In the embodiment of the present application, the Micro display system 3 includes a Micro display 31 and a collimating lens 32, and is configured to emit collimated light to a waveguide system, where the Micro display 31 may be a non-polarized light source (Micro-LED, DLP) or a polarized light source (LCD, OLED, LCOS, etc.); the first optical waveguide 1 and the second optical waveguide 2 are used for transmitting the light coupled into the first optical waveguide 1 and the second optical waveguide 2 to the coupling-out area in a total reflection mode, the first coupling-in grating 6 is used for coupling the light emitted by the micro display system 3 into the first optical waveguide 1, the second coupling-in grating 8 is used for transmitting the light processed by the first polarization state regulating device 4 into the first optical waveguide 1, the first coupling-out grating 7 is used for coupling the light reflected by the first optical waveguide 1 out of the human eye 10 and the light processed by the second polarization state regulating device 5 out of the human eye 10, and the second coupling-out grating 9 is used for coupling the light reflected by the second optical waveguide 2 out of the second polarization state regulating device 5. In the embodiment of the present application, the first optical waveguide 1 and the second optical waveguide 2 are common optical transparent glass, and may be other glass with high refractive index or resin material, and mainly serve as a light transmission carrier of the holographic body grating.

The exposure parameters of the first coupling-in grating 6, the second coupling-in grating 8, the first coupling-out grating 7 and the second coupling-out grating 9 may be the same or different, and are specifically determined according to the type of the gratings (reflective and transmissive) used in the embodiment, and the first polarization state adjusting device 4 and the second polarization state adjusting device 5 are used as phase delay devices, so as to realize adjustment and control on the polarization states of the light rays passing through the first polarization state adjusting device 4 and the second polarization state adjusting device 5. The principle is mainly to control the voltages of the upper electrode and the lower electrode to drive the middle liquid crystal to rotate, thereby generating specific phase delays (such as 0 phase and Pi phase) to change the corresponding polarization states of modulation.

In the embodiment of the present application, the grating periods of the first in-coupling grating 6 and the first out-coupling grating 7 are the same; the periods of the second coupling-in grating 8 and the second coupling-out grating 9 are the same, so that the field of view when the diffracted light is coupled out of the waveguide can be ensured to be consistent with the coupling-in field of view.

As a preferred embodiment of the application, the first incoupling grating 6, the first incoupling grating 7, the second incoupling grating 8 and the second incoupling grating 9 are reflective gratings, transmissive gratings or a combination of reflective and transmissive gratings.

It should be noted that, the first coupling-in grating 6, the first coupling-out grating 7, the second coupling-in grating 8, and the second coupling-out grating 9 are holographic gratings, which may also be referred to as polymer dispersed liquid crystal holographic gratings, the first coupling-in grating 6 and the first coupling-out grating 7 are located in the middle of the first optical waveguide 1, and the second coupling-in grating 8 and the second coupling-out grating 9 are located in the middle of the second optical waveguide 2.

As a preferred embodiment of the present application, a first turning grating is disposed between the first in-coupling grating 6 and the first out-coupling grating 7; a second turning grating is arranged between the second coupling-in grating 8 and the second coupling-out grating 9. The embodiment of the application is provided with the turning grating to expand the exit pupil, so that light transmission can be carried out in two directions, namely a two-dimensional pupil expansion holographic optical waveguide; the non-refractive grating transmits light in only one direction, and is commonly called a one-dimensional pupil-expanding holographic optical waveguide.

In addition, in the embodiment of the application, other substances, namely air filling, are not required to be filled between the first optical waveguide 1 and the second optical waveguide 2 except the electric control liquid crystal wave plate, so that the light rays in the upper layer optical waveguide and the lower layer optical waveguide can meet the total reflection transmission condition and cannot enter other layers for transmission, the step length of light ray transmission is ensured, and the influence of other stray lights is avoided.

It should be noted that the application can be further popularized in the AR optical waveguide display scheme for two-dimensional pupil expansion, and only a piece of refraction grating is added between the coupling-in and coupling-out areas of the optical waveguide respectively, so that other structural devices are kept unchanged, the display light efficiency of the whole optical waveguide system can be improved, and the display effect of the AR optical waveguide is enhanced.

According to the embodiment of the application, the holographic optical waveguide AR display device is adopted, and more effective image light can be transmitted in the optical waveguide by means of diffraction modulation of the coupling-in coupling-out grating and polarization modulation conversion of the polarization state regulating device on the transmitted light, so that other parasitic light influence is not generated, and finally more effective light is coupled out of the optical waveguide and enters the human eye 10 for imaging.

The following detailed description of the present application is given by way of specific examples:

Example 1

As shown in fig. 2, in this embodiment 1, the incident light source is a polarized light source, the incident light source is P polarized light, and the holographic grating is a reflective grating (the incident light source may be a transmissive grating, and the principle is similar to that described in detail below).

When the collimated P polarized light emitted from the micro display system is incident on the coupling-in area of the first optical waveguide 1, the 0 th order light is directly transmitted under the diffraction action of the first coupling-in grating 6, and the 1 st order diffracted light is reflected, and because the lower surface of the first optical waveguide 1 is in contact with air, the 1 st order diffracted light can be transmitted in the first optical waveguide 1 in a total reflection mode until the collimated P polarized light is incident on the first coupling-out grating 7, and is coupled out of the first optical waveguide 1 under the sub-diffraction action of the first coupling-out grating 7, and enters the human eye 10 to be imaged. In general, the diffracted light of low order has strong energy, and the higher order is considered to be absent or very low energy, and does not affect the entire optical waveguide display system. And the optical waveguide generally uses a light order of 1 or-1, and 0 as a relatively high diffraction order that is not used, and reuse needs to be considered.

The 0-level light transmitted by the first coupling-in grating 6 passes through the first polarization state regulating device 4, and is driven by the control voltage to enable the phase delay of the first polarization state regulating device 4 to be 0, so that the transmitted 0-level light polarization state is not changed, namely the transmitted 0-level light is still P-polarized light; when the transmitted 0-order polarized light is incident into the coupling-in region of the second optical waveguide 2, the transmitted 0-order polarized light is reflected under the diffraction action of the second coupling-in grating 8 and is transmitted in the second optical waveguide 2 in a form of total reflection until the transmitted 0-order polarized light is transmitted to the coupling-out region, and is coupled out of the second optical waveguide 2 under the diffraction action of the second coupling-out grating 9, since the light which is coupled out at this time is P-polarized light, when the light directly enters the first coupling-out grating 7 of the first optical waveguide 1, diffraction occurs again, so that the light is deflected and is inconsistent with the light which is coupled out of the first optical waveguide 1, and ghost occurs, therefore, the light which is coupled out of the second optical waveguide 2 needs to be regulated, namely, the polarization state of the coupled-out light needs to be converted from P-polarization into S-polarization through the regulation of the second polarization state regulating device 5, so that the S-polarized light is not modulated when passing through the first coupling-out grating 7, but directly enters the human eye 10 for imaging. The display device can fully utilize the 0-level light transmitted by the coupling-in grating area, improve the energy utilization rate of the optical machine, further improve the light efficiency of the whole optical waveguide display system and enhance the display effect of the AR optical waveguide.

Example 2

As shown in fig. 3, for the incident light source, the incident light source can be regarded as a combination of P-polarized light and S-polarized light, and this embodiment 2 is also described with respect to the holographic grating as a reflective grating (the incident light source can also be a transmissive grating, and the principle is similar to that described in detail below).

Firstly, the micro display system emits unbiased collimated light, which can be decomposed into P polarized light and S polarized light perpendicular to each other, wherein horizontal double arrow in the figure represents P polarized light, and black dot of circle represents S polarized light. When the unpolarized light source is incident to the coupling-in area of the first optical waveguide 1, the 0-order light of the P-polarized light is directly transmitted under the diffraction action of the first coupling-in grating 6, and the 1-order diffracted light is reflected, and since the lower surface of the first optical waveguide 1 is in contact with air, the 1-order diffracted light can be transmitted in the first optical waveguide 1 in a total reflection mode until the light is incident to the first coupling-out grating 7, is coupled out of the first optical waveguide 1 under the diffraction action of the first coupling-out grating 7, and enters the human eye 10 for imaging;

The first incoupling grating 6 is insensitive to the S-polarized light, and almost has no modulation effect, namely, the light directly enters the first polarization state regulating device 4 through the first incoupling grating 6. The first polarization state regulating device 4 generates Pi phase delay under the regulation and control of voltage driving at this time, and rotates the polarization direction of all light rays passing through the first polarization state regulating device 4 by 90 degrees, namely, P polarized light transmitted by level 0 is converted into S polarized light, and the S polarized light is directly emitted to the external environment through the second coupling-in grating 8; so the S polarized light in the unpolarized light source is converted into P polarized light under the control of the first polarization state control device 4 and is incident into the second optical waveguide 2, and when incident into the coupling-in region of the second optical waveguide 2, is transmitted in the second optical waveguide 2 in the form of total reflection by the diffraction action of the second coupling-in grating 8 until being transmitted to the coupling-out region, and is coupled out of the second optical waveguide 2 by the diffraction action of the second coupling-out grating 9. Since the light is P polarized light at this time, when the light directly enters the first coupling-out grating 7 of the first optical waveguide 1, diffraction occurs again to cause light deflection, so that the light is inconsistent with the light coupled out of the first optical waveguide 1, and ghost occurs, so that the light coupled out of the second optical waveguide 2 needs to be regulated and controlled, that is, the polarization state of the coupled-out light needs to be regulated and controlled by the second polarization state regulating device 5, so that the polarization state of the coupled-out light is converted from P polarization to S polarization, and thus, the light of the S polarization is not modulated when passing through the first coupling-out grating 7, but directly enters the human eye 10 for imaging. Therefore, the display device provided by the application can respectively modulate different polarization states of the display image source, thereby doubling the energy utilization rate of the display optical machine, further improving the light efficiency of the whole optical waveguide display system and enhancing the display effect of the AR optical waveguide.

In embodiment 2, in principle, a plurality of second optical waveguides 2 may be disposed below the second optical waveguides 2, and a first polarization state adjusting device 4 and the second polarization state adjusting device 5 are disposed between each second optical waveguide 2, so as to further improve the display light efficiency of unpolarized light.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application.

Claims (7)

1. A display device employing holographic optical waveguides AR, the device comprising a micro display system, a first optical waveguide and a second optical waveguide;

the first optical waveguide is provided with a first coupling-in grating and a first coupling-out grating;

the second optical waveguide is provided with a second coupling-in grating and a second coupling-out grating;

the first optical waveguide is arranged on the upper surface of the second optical waveguide, the region of the first coupling-in grating arranged on the first optical waveguide corresponds to the region of the second coupling-in grating arranged on the second optical waveguide, and the region of the first coupling-out grating arranged on the first optical waveguide corresponds to the region of the second coupling-out grating arranged on the second optical waveguide;

A first polarization state regulating device and a second polarization state regulating device are arranged between the first optical waveguide and the second optical waveguide, the first polarization state regulating device is arranged in a region corresponding to the first coupling-in grating or the second coupling-in grating, the second polarization state regulating device is arranged in a region corresponding to the first coupling-out grating or the second coupling-out grating, and the first polarization state regulating device and the second polarization state regulating device are respectively used for regulating and controlling the light polarization state;

The micro display system is used for emitting collimated light, and the collimated light transmitted by the first coupling-in grating is incident to the first polarization state regulating device for polarization state regulation after passing through the first optical waveguide, then is incident to the second polarization state regulating device for polarization state regulation after passing through the second coupling-in grating, the second optical waveguide and the second coupling-out grating, and enters the human eye for imaging after passing through the first optical waveguide and the first coupling-out grating.

2. A display device employing a holographic optical waveguide AR as in claim 1, wherein said micro-display system comprises: a micro display and a collimating lens;

and emitting image light through the micro display, wherein the image light is processed by the collimating lens to obtain collimated light.

3. A display device employing a holographic optical waveguide AR as claimed in claim 2, wherein said image light is a polarized light source or an unpolarized light source.

4. The AR display device according to claim 1, wherein the first in-coupling grating, the first out-coupling grating, the second in-coupling grating, and the second out-coupling grating are reflective gratings, transmissive gratings, or a combination of reflective and transmissive gratings.

5. The AR display device using holographic optical waveguide of claim 1, wherein a first turning grating is disposed between the first in-coupling grating and the first out-coupling grating region;

and a second turning grating is arranged between the second coupling-in grating and the second coupling-out grating region.

6. The AR display device using holographic optical waveguide of claim 1, wherein the grating periods of the first in-grating and the first out-grating are the same;

The periods of the second in-coupling grating and the second out-coupling grating are the same.

7. The AR display device using holographic optical waveguide according to claim 1, wherein the first polarization state adjusting device and the second polarization state adjusting device are electrically controlled liquid crystal waveplates; or alternatively, the first and second heat exchangers may be,

The first polarization state regulating device is an electric control liquid crystal wave plate, and the second polarization state regulating device is a half wave plate.