The present disclosure relates to the optical technology, in particular to a waveguide-based augmented reality display apparatus.
Augmented reality (or mixed reality) display technology may superimpose virtual images into the real world to achieve the purpose of fusing virtual information with the real world. Augmented reality display technology can enhance information expressed in the real world, so it has broad application prospects in education, remote cooperation, traffic navigation and other fields. The waveguide-based augmented reality display apparatus has the advantages of compact structure, small size and easy for the exit pupil to expand, and has been used in products by Microsoft, Sony, Magicleap and other companies.
Due to the limitation of total reflection condition of waveguide, the field of view of the waveguide-based augmented reality display apparatus is generally small. The traditional waveguide augmented reality display apparatus is usually provided with two waveguides in order to increase the field of view, wherein, one waveguide is used to transmit a light beam generated by an image source according to image data of a left half of a displayed image, and the other waveguide is used to transmit a light beam generated by the image source according to image data of a right half of the displayed image, so as to increase the field of view. However, the dual-waveguide configuration will increase the thickness and weight of the waveguide display apparatus, which will greatly reduce user experience of the waveguide display apparatus.
Therefore, it is necessary to provide a waveguide display apparatus which can increase a field of view and has a compact structure.
The present disclosure provides a waveguide-based augmented reality display apparatus, which includes:
an image source, configured to display an image and generate a light beam according to image data of the displayed image, wherein the light beam includes a first polarized light and a second polarized light alternately displayed at a preset frequency, the first polarized light has a first polarization state and the second polarized light has a second polarization state different from the first polarization state;
a single waveguide, being spaced from the image source;
a first in-coupling device, arranged on one side of the waveguide adjacent to the image source, and configured to couple the first polarized light into the waveguide;
a second in-coupling device, arranged on one side of the waveguide away from the first in-coupling device, and configured to couple the second polarized light into the waveguide;
a first out-coupling device, arranged on one side of the waveguide adjacent to the image source, and configured to couple out a first sub-image of the first polarized light propagating in the waveguide in a preset area; and
a second out-coupling device, arranged on one side of the waveguide away from the first out-coupling device, and configured to couple out a second sub-image of the second polarized light propagating in the waveguide in the same preset area;
wherein, an out-coupling grating vector of the first polarized light and a out-coupling grating vector of the second polarized light have different directions, and the first sub-image and the second sub-image are alternately displayed, and are fused and superimposed in human eyes due to a persistence of vision.
In one embodiment, the first in-coupling device and the first out-coupling device are transmission gratings, and the second in-coupling device and the second out-coupling device are reflection gratings;
the second polarized light is coupled into the waveguide through the second in-coupling device, totally reflected in the waveguide and transmitted to the second out-coupling device, and then coupled out to the preset area through the second out-coupling device and the first out-coupling device sequentially.
In one embodiment, the first polarization state and the second polarization state are an S polarization state and a P polarization state, respectively.
In one embodiment, the first polarization state and the second polarization state are a left-handed circular polarization state and a right-handed circular polarization state, respectively.
In one embodiment, the image source includes an image display for displaying the image and a polarization modulator arranged on one side of the image display adjacent to the waveguide. The polarization modulator is configured to generate the first polarized light and the second polarized light displayed alternately based on the image data of the image.
In one embodiment, the first in-coupling device and the second in-coupling device are arranged on opposite sides of the waveguide and are aligned coaxially with an optical axis.
In one embodiment, the first out-coupling device and the second out-coupling device are arranged on opposite sides of the waveguide and are aligned coaxially with an optical axis.
In one embodiment, the image source is configured to alternately form the first polarized light and the second polarized light at a frequency greater than or equal to 48 frames per second, so that the display frequencies of the coupled-out first sub-image and the second sub-image are greater than or equal to 24 frames per second, respectively.
In one embodiment, the waveguide-based augmented reality display apparatus further includes a collimator arranged between the image source and the waveguide. The collimator is configured to process the first polarized light and the second polarized light into a collimated light.
In one embodiment, the first out-coupling device and the second out-coupling device have a grating vector of
, wherein k0=2π/λx, and x=1 or 2; wherein λ1 represents a wavelength of the first polarized light, and λ2 represents a wavelength of the second polarized light, n1 represents a refractive index of the waveguide; an out-coupling grating of the first out-coupling device and an out-coupling grating of the second out-coupling device have an angle of φ with a respective corresponding in-coupling grating, wherein φ=π/2-θ,
The present disclosure provides a waveguide-based augmented reality display apparatus, which can realize the expansion of the field of view only by setting a single waveguide. Moreover, the image source alternately displays the images of the left and right fields of view to achieve the purpose of improving the resolution of the displayed image. In the above waveguide display apparatus, the light beams generated by the image source include the first polarized light and the second polarized light alternately displayed at the preset frequency. The first polarized light has the first polarization state, and the second polarized light has the second polarization state different from the first polarization state. Since the first in-coupling device and the second in-coupling device located on both sides of the single waveguide have a polarization selectivity, the first in-coupling device located on the side of the waveguide adjacent to the image source may only diffract the first polarized light, but not the second polarized light, while the second in-coupling device located on the side of the waveguide away from the first in-coupling device may only diffract the second polarized light, but not the first polarized light. Therefore, the first polarized light and the second polarized light alternately generated by the image source at the preset frequency may be coupled into the waveguide by the first in-coupling device and the second in-coupling device respectively, and then the first sub-image and the second sub-image are coupled out of the first polarized light and the second polarized light propagating in the waveguide in the same preset area by the out-coupling device respectively. Since the coupled-out first sub-image and the second sub-image are alternately displayed in human eyes, based on the persistence of human vision, the human eyes will automatically fuse and superimpose the first sub-image and the second sub-image into a total image. Therefore, the above waveguide display apparatus can realize the superposition and doubling of two different fields of view through the single waveguide. Compared with the traditional waveguide display apparatus with dual-waveguide, the thickness and weight of the waveguide display apparatus are reduced. At the same time, because the first sub-image and the second sub-image have corresponding resolutions, the resolution of the fused total image is equal to the superposition of the resolutions of the first sub-image and the second sub-image. Therefore, the present solution can significantly increase the field of view and the resolution of the image on the premise of ensuring a compact structure of the waveguide display apparatus, and greatly improve the user experience.
The present disclosure will be further illustrated with reference to the accompanying drawings and embodiments.
As shown in
Specifically, for convenience of description, the corresponding grating vectors of the light beams in the in-coupling device 11, the deflector 12 and the out-coupling device 13 are respectively denoted as K1, K2and K3, and the corresponding propagation periods of the light beams in the in-coupling device 11, the waveguide 12 and the out-coupling device 13 are respectively denoted as Λ1, Λ2 and Λ3. The direction of the grating vector is parallel to a corresponding grating period direction;
A magnitude of K1: |K1|=2π/Λ1;
A magnitude of K2: |K2|=2π/Λ2; and
A magnitude of K3: |K3|=2π/Λ3.
As shown in
As shown in
The waveguide 300 is spaced from the image source 100, and there is one waveguide 300. The first in-coupling device 400 is arranged on one side of the waveguide 300 adjacent to the image source 100, and the first in-coupling device 400 is configured to couple the first polarized light into the waveguide 300. The second in-coupling device 500 is arranged on one side of the waveguide 300 away from the first in-coupling device 400, and the second in-coupling device 500 is configured to couple the second polarized light into the waveguide 300. The first out-coupling device 600 is arranged on the waveguide 300, and the first out-coupling device 600 is configured to couple out a first sub-image of the first polarized light propagating in the waveguide 300 in a preset area. The second out-coupling device 700 is arranged on one side of the waveguide 300 away from the first out-coupling device 600, and the second out-coupling device 700 is configured to couple out a second sub-image of the second polarized light propagating in the waveguide 300 in the same preset area. The first sub-image and the second sub-image are alternately displayed in human eyes, and are fused and superimposed due to a persistence of vision.
As shown in
As shown in
Preferably, the image source 100 alternately forms the first polarized light and the second polarized light at a frequency greater than or equal to 48 frames per second, so that the display frequencies of the coupled-out first sub-image and the coupled-out second sub-image are greater than or equal to 24 frames per second, respectively, thereby ensuring that the picture finally seen by human eyes is continuous.
Further, the first in-coupling device 400 and the second in-coupling device 500 are arranged on opposite sides of the waveguide 300 and are aligned coaxially with an optical axis. Specifically, the first in-coupling device 400 and the second in-coupling device 500 are arranged on the two opposite sides of the waveguide 300 in a thickness direction and are in aligned coaxially with the optical axis.
In an embodiment, the first polarization state and the second polarization state are an S polarization state and a P polarization state, respectively. It can be understand that in other embodiments, the first polarization state and the second polarization state are a left-handed circular polarization state and a right-handed circular polarization state, respectively.
As shown in
As shown in
In an embodiment, the above waveguide display apparatus 10 further includes a controller. The controller is electrically connected with the image display 120 and the polarization modulator 140. The controller is configured to control an operation of the image display 120 and the polarization modulator 140.
As shown in
As shown in
Specifically, the grating vectors corresponding to the first polarized light in the first in-coupling device 400, the deflector and the first out-coupling device 600 are respectively a first solid line with arrow 23, a second solid line with arrow 24 and a third solid line with arrow 25 shown in
, and a corresponding grating period is
, which is larger than A1. The deflection angle of the grating direction is
As shown in
Since the sum of the corresponding grating vectors of the first polarized light in the first in-coupling device 400, the deflector, and the first out-coupling device 600, and the sum of the corresponding grating vectors of the second polarized light in the second in-coupling device 500, the deflector and second out-coupling device 700 are not zero, the coupled-out first sub-image and/or the second sub-image may be dispersed, which is not conducive to a color display of the final image. In the present solution, the first sub-image and the second sub-image may be displayed by the MEMS laser scanning display with a narrow wavelength bandwidth.
In the above waveguide display apparatus 10, the light beams generated by the image source 100 include the first polarized light and the second polarized light alternately displayed at the preset frequency. The first polarized light has the first polarization state, and the second polarized light has the second polarization state different from the first polarization state. Since the first in-coupling device 400 and the second in-coupling device 500 located on both sides of the single waveguide 300 have a polarization selectivity, the first in-coupling device 400 located on the side of the waveguide 300 adjacent to the image source 100 may only diffract the first polarized light, but not the second polarized light, while the second in-coupling device 500 located on the side of the waveguide 300 away from the first in-coupling device 400 may only diffract the second polarized light, but not the first polarized light. Therefore, the first polarized light and the second polarized light alternately generated by the image source 100 at the preset frequency may be coupled into the waveguide 300 by the first in-coupling device 400 and the second in-coupling device 500 respectively, and then the first sub-image and the second sub-image are respectively coupled out of the first polarized light and the second polarized light propagating in the waveguide 300 in the same preset area by the out-coupling device. Since the coupled-out first sub-image and the second sub-image are alternately displayed in human eyes, based on the persistence of human vision, the human eyes will automatically fuse and superimpose the first sub-image and the second sub-image into a total image. Therefore, the above waveguide display apparatus 10 realize the superposition and doubling of two different fields of view through the single waveguide 300. Compared with the traditional waveguide display apparatus with dual-waveguide, the thickness and weight of the waveguide display apparatus 10 are reduced. At the same time, because the first sub-image and the second sub-image have corresponding resolutions, the resolution of the fused total image is equal to the superposition of the resolutions of the first sub-image and the second sub-image. Therefore, the present solution can significantly increase the field of view and the resolution of the image on the premise of ensuring a compact structure of the waveguide display apparatus 10, and greatly improve the user experience.
The above is merely embodiments of the present disclosure. It should be appreciated that, those of ordinary skills in the art may make improvements without departing from the inventive concept of the present disclosure, such improvements, however, fall within the protection scope of the present disclosure.
Number | Date | Country | Kind |
---|---|---|---|
201910804476.3 | Aug 2019 | CN | national |
Number | Date | Country | |
---|---|---|---|
Parent | PCT/CN2019/104519 | Sep 2019 | US |
Child | 17035787 | US |