CN216979348U - Illumination system and optical-mechanical system - Google Patents

Abstract

The embodiment of the application provides an illumination system, which comprises an optical waveguide and an outcoupling grating, wherein the optical waveguide is used for receiving incident light and transmitting the incident light in a total reflection mode. The coupling grating is arranged in the optical waveguide, and the grating period of the coupling grating is gradually changed along a preset direction, so that the light coupled out from the coupling grating is converged towards the center of the coupling grating. The optical waveguide with smaller thickness and the coupled grating are adopted for light illumination, so that the illumination system is lighter and thinner, and the optical-mechanical system is favorably applied to optical-mechanical systems with higher requirements on volume and weight, such as virtual display equipment. In addition, the embodiment of the application also provides an optical-mechanical system.

Description

Illumination system and optical-mechanical system

Technical Field

The application relates to the technical field of projection, in particular to an illumination system and an optical-mechanical system.

Background

Augmented Reality (AR) is a display technology that collects real world information in real time and combines virtual information, images, and the like with the real world, is expected to become a new generation of information interaction terminal following personal computers and smart phones, and has a wide market scale and imagination space. Firstly, in information display, the AR is not limited to an entity screen any more, but can be displayed in the whole physical space, and virtual information is displayed in real time on the basis of a physical entity by adopting a virtual-real combined mode, namely augmented reality display; secondly, in the aspect of human-computer interaction, instruction collection can break through an operation interface of an entity, and a more natural and convenient interaction mode such as voice, gestures, images and the like is used, so that a human-computer interaction mode is more like natural communication with people.

The opto-mechanical system in the AR device is used to generate a projection display image, among which there are mainly LCoS or DMD based projection systems.

Liquid crystal On Silicon (LCoS) is a new type of microdisplay technology that combines semiconductor and LCD technologies. It is often necessary to provide one or more PBS prisms that are bulky as part of the illumination system, and therefore the overall volume and weight of the device is large. The DLP projection display technology is a projection display technology taking a DMD device as a core, a DMD chip is applied to form a projection display system, and the DLP projection system generally adopts a light source with an ellipsoidal reflecting bowl and a square rod illumination system, so that the illumination system has the problem of generally large volume.

For optical-mechanical systems such as AR devices, projection light spots of the optical-mechanical systems in the prior art are too large to be well matched with the AR devices, and therefore it is necessary to design thinner optical-mechanical systems.

SUMMERY OF THE UTILITY MODEL

An object of the present application is to provide an illumination system and an optical-mechanical system to improve the above-mentioned problems.

In a first aspect, embodiments of the present application provide an illumination system, which includes an optical waveguide and an outcoupling grating, the optical waveguide being configured to receive incident light and to conduct the incident light in a total reflection manner. The coupling grating is arranged in the optical waveguide, and the grating period of the coupling grating is gradually changed along a preset direction, so that the light coupled out from the coupling grating is converged towards the center of the coupling grating.

In some embodiments, the out-coupling grating is a straight grating.

In some embodiments, the grating period of the outcoupled grating gradually increases or gradually decreases along a single direction.

In some embodiments, the grating period of the out-coupling grating gradually increases along the direction of travel of the incident light within the optical waveguide.

In some embodiments, the grating period of the outcoupled grating gradually increases or gradually decreases in a plurality of different directions.

In some embodiments, the center of the coupled-out grating is taken as a circular point, and the grating period of the coupled-out grating gradually increases or gradually decreases along the radial direction of the circular point.

In some embodiments, the illumination system further comprises a coupling-in device for receiving incident light and coupling the incident light into the optical waveguide such that the incident light is totally reflected within the optical waveguide.

In a second aspect, an embodiment of the present application further provides an optical-mechanical system, which includes the above-mentioned illumination system, a spatial light modulator, and a projection lens, where the spatial light modulator receives and modulates the illumination light emitted from the illumination system to form image light, and the projection lens is used to display the image light.

In some embodiments, the spatial light modulator and the projection lens are located on opposite sides of the optical waveguide, and the spatial light modulator modulates the image light formed by the illumination light to pass through the optical waveguide and enter the projection lens.

In some embodiments, the opto-mechanical system further includes a polarizer for filtering the image light, and the projection lens is configured to display the image light after passing through the polarizer.

The application provides a lighting system and ray apparatus system adopts the less optical waveguide of thickness size to carry out the light illumination, consequently can make lighting system more frivolous, does benefit to and is applied to among the ray apparatus system that virtual display device etc. have a higher demand to volume and weight.

These and other aspects of the present application will be more readily apparent from the following description of the embodiments.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of diffraction of a diffraction grating according to an embodiment of the present application.

Fig. 2 is a schematic structural diagram of an optical-mechanical system according to an embodiment of the present disclosure.

Fig. 3 is a schematic structural diagram of another opto-mechanical system according to an embodiment of the present disclosure.

Fig. 4 is a schematic structural diagram of a coupling-in device provided in an embodiment of the present application.

Fig. 5 is a schematic structural diagram of another coupling-in device provided in the embodiment of the present application.

Fig. 6 is a schematic structural diagram of another coupling-in device provided in the embodiment of the present application.

Fig. 7 is a schematic diagram of the optical path of incident light when the diffraction grating with different grating periods diffracts.

Fig. 8 is an optical path diagram of an outcoupling grating provided in an embodiment of the present application.

Fig. 9 is a schematic diagram of a grating period distribution of an outcoupled grating provided in an embodiment of the present application.

Fig. 10 is a schematic diagram of another grating period distribution of the coupled-out grating provided in the embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the exit path of each level of diffracted light when incident light is incident on a diffraction grating, where d is the period of the grating structure and θ_mFor the diffraction angle, m is the diffraction order, and λ is the wavelength of the light beam, the grating equation can be expressed as dsin θ_m＝mλ。

From the grating equation, it can be seen that, when the wavelength λ is constant, the larger the period d is, the larger the diffraction angle θ of each level of diffracted light_mThe smaller.

First embodiment

Referring to fig. 2, the embodiment provides an optical-mechanical system 10, where the optical-mechanical system 10 includes an illumination system 20, a spatial light modulator 30 and a projection lens 50, where the illumination system 20 is configured to generate illumination light, the spatial light modulator 30 receives the illumination light and modulates the illumination light into image light, and the image light enters the projection lens 50 for display.

Specifically, the illumination system 20 includes the optical waveguide 100 and the coupling-out grating 300, and the coupling-out grating 300 is disposed on the optical waveguide 100. The optical waveguide 100 includes a first surface 110 and a second surface 120 opposite to each other, the first surface 110 and the second surface 120 are substantially parallel to each other, and the optical waveguide 100 can propagate light, specifically, when incident light enters the optical waveguide, the incident light propagates in the optical waveguide in a total reflection manner.

Where the incident light may be polarized light, e.g., S-polarized light, the incident light may be generated by a light source, which in one embodiment may be a linearly polarized laser. In another embodiment, the light source may include an LED light source or other type of laser and a polarizer, and a light beam emitted from the LED light source or other type of laser passes through the polarizer and is collimated and homogenized to form a uniform spot as an incident light with a single polarization state. The incident light emitted from the light source may be white light or monochromatic light, and is not limited herein.

In some embodiments, as shown in fig. 3, the illumination system 20 may further include a coupling-in device 200, where the coupling-in device 200 is configured to receive incident light and couple the incident light into the optical waveguide 100, so that the incident light is totally reflected in the optical waveguide 100, and the totally reflected incident light propagates toward the coupling-out grating 300. By changing the incident angle of the incident light upon the optical waveguide 100, the incident light satisfies the total reflection condition, and total reflection can be achieved within the optical waveguide 100.

As an implementation manner, in this embodiment, as shown in fig. 4, the incoupling device 200 includes a prism 210, where the prism 210 may be a triangular prism 210, the refractive index of the prism 210 may be greater than 1, the prism 210 is disposed on the second surface 120 of the incoupling region, the prism 210 has an incident surface, an attaching surface, and a back surface opposite to the incident surface, the attaching surface is attached to the second surface 120, and the incident surface is used for receiving incident light and feeding the incident light into the optical waveguide 100, so that the incident light is totally reflected on the surface of the optical waveguide 100. Further, the back surface may be further provided with a light absorption layer 220, and the light absorption layer 220 may absorb light, so as to prevent incident light from escaping from the back surface to form a thermal effect. Specifically, the light absorbing layer 220 may be a light absorbing adhesive, and is formed on the back surface by adhesion.

In another embodiment, as shown in fig. 5, the coupling-in device 200 may also adopt a surface relief grating/holographic grating manner, specifically, the second surface 120 of the optical waveguide 100 is processed with a layer of surface relief grating 240 as the coupling-in device 200, and the width of the grating region is the width of the light traveling after the light is totally reflected once in the optical waveguide 100, at this time, the incident light is perpendicularly incident to the surface relief grating 240, so that the T of the surface relief grating 240 is further caused₁Order diffraction or T_-1The order diffraction propagates towards the outcoupling grating 300 at a certain diffraction angle, such that T₁Order diffraction or T_-1The order diffraction may be totally reflected within the optical waveguide 100 and into the outcoupling grating 300. Note that, the control T₁Order diffraction or T_-1Diffraction angle of order diffraction ofBy controlling the grating parameters of the surface relief grating 240.

In another embodiment, as shown in fig. 6, the coupling-in device 200 may also be configured in a form of wedge-angle total reflection, the end surface of the optical waveguide 100 located on the optical waveguide 100 is configured as an inclined surface, and the light reflection layer 230 is configured as the coupling-in device 200 on the inclined surface, and the light is incident on the inclined surface in a manner perpendicular to the second surface 120, and the light is totally reflected on the inclined surface and enters the optical waveguide 100. By adjusting the angle of the slope, the total reflection angle of the light in the optical waveguide 100 can be adjusted, so that the light can reach the outcoupling grating 300 via total reflection, and the slope may be 30 ° -60 ° for example.

The coupling-out grating 300 is disposed on the second surface 120, and the grating period of the coupling-out grating 300 is gradually changed along a predetermined direction, so that the light coupled out from the coupling-out grating 300 converges towards the center of the coupling-out grating 300. The outcoupling grating 300 serves to outcouple incident light transmitted by the optical waveguide 100. Specifically, the incident light enters the coupling grating 300 after being totally reflected once or multiple times in the optical waveguide 100, and is emitted through the coupling grating 300 to form the illumination light.

The coupling-out grating 300 may be a surface relief grating, which may be mass-produced by a nano-imprint process, and the mass production type and reliability of the surface relief grating have obvious advantages compared to other gratings such as bragg gratings, and the response spectrum of the surface relief grating is not limited by the processing material, and has a wider spectral response range, which is more beneficial to forming stable and uniform illumination light. The outcoupling grating 300 may be a straight grating, an oblique grating, a blazed grating, or the like, and is not limited herein. Preferably, the coupling grating 300 may be a straight grating, which is convenient to process and can control the diffraction angle of the diffracted light more precisely for each order of diffracted light, so as to precisely control the exit path of the diffracted light.

FIG. 7 is a diagram showing diffraction angles of diffracted light rays of two diffraction gratings with different grating periods, respectively, wherein the grating period of the left graph is greater than that of the right graph, and it can be seen that when the grating period is greater, the diffraction grating has a larger value for T_-1Angle of deflection of diffracted light of orderThe greater the degree. Therefore, by utilizing the diffraction characteristics of the diffraction grating, a diffraction grating structure with gradually changed grating period can be manufactured, so that the deflection direction of the specific diffraction main ray is gradually increased or decreased. This may cause the illumination light exiting from the outcoupling grating 300 to converge towards the center of the outcoupling grating 300, wherein converging means that the light converges towards the center.

In a more specific embodiment, the grating period of the outcoupling grating 300 is gradually increased or gradually decreased in a single direction. Therein, in particular, as shown in fig. 8 and 9, the grating period of the outcoupling grating 300 gradually increases in the traveling direction of the incident light within the optical waveguide, wherein darker colors in fig. 8 and 9 represent larger grating periods. Taking the example that the grating period of the coupling grating 300 gradually increases along the traveling direction of the incident light in the optical waveguide, when the incident light enters the optical waveguide and totally reflects along the traveling direction, the grating period increases periodically, and at this time, the coupling grating 300 is aligned to the T of the incident light_-1The deflection angle of the order diffraction light is larger and larger, the coupled-out light beam forms an effect of converging towards the middle of the coupled-out grating 300, so that the light coupled out from the edge of the coupled-out grating 300 can also irradiate into the spatial light modulator 30, and because the illumination light incident on the spatial light modulator 30 converges towards the center, the efficiency of the coupled-out light beam entering the spatial light modulator 30 can be improved, meanwhile, the illumination light is not vertically incident relative to the spatial light modulator 30, and therefore, after being modulated by the spatial light modulator 30, the formed image light further converges towards the center, and the field lens effect is realized.

It is understood that in other embodiments, the grating period of the outcoupling grating 300 may be gradually increased or gradually decreased in other directions, and the above-mentioned effects can also be achieved, which is not limited herein.

In another embodiment, the grating period of the outcoupling grating 300 may be gradually increased or gradually decreased in a plurality of different directions. For example, in a more specific embodiment, as shown in FIG. 10, wherein darker colors represent larger grating periods in FIG. 10. With the center of the coupling-out grating 300 as a dot, the grating period of the coupling-out grating 300 gradually increases along the radial direction of the dot. Therefore, the light coupled out from the edge of each direction of the coupling grating 300 can converge towards the center of the coupling grating 300, the convergence effect is better, and because the illumination light incident on the spatial light modulator 30 converges towards the center, the efficiency of the coupled light beam entering the spatial light modulator 30 can be improved, and meanwhile, the illumination light is not vertically incident relative to the spatial light modulator 30, the formed image light can further converge towards the center after being modulated by the spatial light modulator 30, and the field lens effect is realized.

It is understood that, in other embodiments, any point of the outcoupling grating 300 may be a circular point, and the grating period of the outcoupling grating 300 is configured to gradually increase along the radial direction of the circular point, which also can achieve the above-mentioned effects, and is not limited herein.

The illumination light emitted from the coupling-out grating 300 in the coupling-out region is emitted and incident on the spatial light modulator 30, and the light spot of the illumination light is larger than or equal to the size of the spatial light modulator 30, so that imaging can be realized at all positions of the spatial light modulator 30. The spot of the illumination light is smaller than the area of the outcoupling grating 300.

The spatial light modulator 30 may be an LCoS device or a DMD device, but is not limited thereto. In this embodiment, the spatial light modulator 30 is an LCoS device, and the spatial light modulator 30 is disposed corresponding to the light coupling grating 300 and located on two opposite sides of the optical waveguide 100 with respect to the projection lens 50. The illumination light may directly enter the spatial light modulator 30, and the spatial light modulator 30 receives and modulates the illumination light emitted from the illumination system 20, forms image light, and emits the image light toward the optical waveguide 100. The image light passes through the coupling grating 300 and the optical waveguide 100 and is emitted.

In this embodiment, a polarizer 40 may be further included, the polarizer 40 is disposed on a side of the optical waveguide 100 far away from the spatial light modulator 30, and is located between the projection lens 50 and the optical waveguide 100, and the polarizer 40 is located on an outgoing light path of the image light, when the image light passes through the polarizer 40, the polarizer 40 may filter the image light, so that the image light with a specified polarization state can pass through and enter the projection lens 50. Specifically, in this embodiment, the polarizer 40 may transmit P-polarized light. The projection lens 50 is located on the side of the optical waveguide 100 remote from the spatial light modulator 30.

Taking the incident light as S-polarized light as an example, the polarization state of the light is unchanged and the light is S-polarized light when the light propagates in the optical waveguide 100. Specifically, when the illumination light is irradiated to the spatial light modulator 30, the bright-state pixels convert the s light into the p light, and the p light may enter the projection lens 50 through the waveguide and the polarizer 40. The dark state pixels reflect only s light, which passes through the waveguide and then does not pass through the polarizer 40 and enter the projection lens 50.

In the present embodiment, the polarizer 40 may be an absorption polarizer that transmits P-polarized light and absorbs S-polarized light. The polarizer 40 may be a reflective polarizer, and may transmit P-polarized light and reflect S-polarized light, and the reflected S-polarized light may reenter the optical waveguide 100 to form illumination light and enter the spatial light modulator 30 for modulation, thereby improving light efficiency.

The illumination system 20 provided by the embodiment of the invention emits the illumination light by using the optical waveguide 100 and the grating structure, so that the overall volume and the weight are small, and both the illumination light and the image light converge toward the center to realize the field lens effect, so that the illumination system can be applied to an AR device as the optical-mechanical system 10, which is beneficial to reducing the wearing load of a user and improving the use experience of the user.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (10)

1. An illumination system, characterized in that the illumination system comprises:

the optical waveguide is used for receiving incident light and conducting the incident light in a total reflection mode;

and the grating period of the coupling-out grating is gradually changed along a preset direction, so that the light coupled out from the coupling-out grating converges towards the center of the coupling-out grating.

2. The illumination system of claim 1, wherein the outcoupling grating is a straight grating.

3. The illumination system of claim 1, wherein the grating period of the out-coupling grating gradually increases or gradually decreases along a single direction.

4. An illumination system according to claim 3, characterized in that the grating period of the out-coupling grating increases gradually along the direction of travel of the incident light within the optical waveguide.

5. The illumination system of claim 1, wherein the grating period of the out-coupling grating gradually increases or gradually decreases in a plurality of different directions.

6. The illumination system of claim 5, wherein the center of the out-coupling grating is a circular point, and the grating period of the out-coupling grating gradually increases or gradually decreases along the radial direction of the circular point.

7. An illumination system according to claim 1, further comprising coupling-in means for receiving incident light and coupling said incident light into said optical waveguide such that said incident light is totally reflected within said optical waveguide.

8. An opto-mechanical system comprising an illumination system according to any of claims 1 to 7, a spatial light modulator for receiving and modulating illumination light from the illumination system to form image light, and a projection lens for displaying the image light.

9. The optical-mechanical system of claim 8, wherein the spatial light modulator and the projection lens are located on opposite sides of the optical waveguide, and the spatial light modulator modulates the image light formed by the illumination light to enter the projection lens after passing through the optical waveguide.

10. The opto-mechanical system of claim 8 or 9, further comprising a polarizer for filtering the image light, wherein the projection lens is configured to display the image light after passing through the polarizer.

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