CN216979350U - Illumination system and optical-mechanical system - Google Patents
Illumination system and optical-mechanical system Download PDFInfo
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- CN216979350U CN216979350U CN202123450824.3U CN202123450824U CN216979350U CN 216979350 U CN216979350 U CN 216979350U CN 202123450824 U CN202123450824 U CN 202123450824U CN 216979350 U CN216979350 U CN 216979350U
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Abstract
An illumination system includes an optical waveguide, a coupling-in device disposed in a coupling-in region for receiving an incident light of a single polarization state and coupling the incident light into the optical waveguide, so that the incident light is totally reflected within the optical waveguide, and a coupling-out grating. The light coupling grating is arranged in the light coupling-out area, the light coupling-out grating is provided with a plurality of grooves, the grooves are filled with a birefringent crystal layer, the light coupling-out grating is used for coupling out incident light conducted by the optical waveguide to form illuminating light emitted out of the light coupling-out area in a direction perpendicular to the light coupling-out area, and the light coupling-out grating is also used for transmitting image light. The optical waveguide with smaller thickness dimension is adopted for light illumination, so that the illumination system is lighter and thinner, and the optical waveguide 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
Technical Field
The application relates to the technical field of projection, in particular to an illumination system and an optical machine 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 the 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 in a virtual-real combination 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, which 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, the size and weight of the optical-mechanical systems in the prior art are too large, and therefore it is necessary to design thinner optical-mechanical systems.
SUMMERY OF THE UTILITY MODEL
The present application aims to provide a lighting system and an optical-mechanical system to improve the above problems.
In a first aspect, an embodiment of the present application provides an illumination system, which includes an optical waveguide, an incoupling device and an outcoupling grating, wherein the incoupling device is disposed in the incoupling region and is configured to receive incident light of a single polarization state and couple the incident light into the optical waveguide, so that the incident light is totally reflected within the optical waveguide. The coupling-out grating is arranged in the coupling-out area, is a surface relief grating and is provided with a plurality of grooves, a birefringent crystal layer is filled in the grooves, the coupling-out grating is used for coupling out incident light transmitted by the optical waveguide to form illuminating light emitted vertical to the coupling-out area, and the coupling-out grating is also used for transmitting image light.
In a second aspect, an embodiment of the present application further provides an optical-mechanical system, which includes at least one illumination system as described above, a spatial light modulator, a polarizer, and a projection lens, where the spatial light modulator receives and modulates illumination light emitted from the illumination system, forms image light, and emits the image light toward the optical waveguide, the polarizer is used to filter the image light, the projection lens is used to display the image light after passing through the polarizer, and the projection lens is located on a side of the optical waveguide away from the spatial light modulator.
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, can be applied to virtual display device etc. and require in the higher ray apparatus system to volume and weight. Simultaneously, through set up birefringent crystal layer in the slot of coupling out the grating, birefringent crystal layer can be when seeing through image light, directly sees through the ordinary light in the image light, improves the transmissivity of image light, improves the display brightness of image light, and in addition, birefringent crystal layer still carries out the deflection of more levels to the extraordinary light in the image light, makes it be difficult for seeing through coupling out the grating, can increase the contrast of image light.
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 structural diagram of an optical-mechanical system according to a first embodiment of the present disclosure.
Fig. 2 is a schematic structural diagram of a coupling-in device provided in the first embodiment of the present application.
Fig. 3 is a schematic structural diagram of another coupling-in device provided in the first embodiment of the present application.
Fig. 4 is a schematic structural diagram of another coupling-in device provided in the first embodiment of the present application.
Fig. 5 is a schematic diagram illustrating the propagation of incident light in an optical waveguide in the optical-mechanical system according to the first embodiment of the present application.
Fig. 6 is a schematic diagram of a structure of a outcoupling grating provided in the first embodiment of the present application.
Fig. 7 is a schematic diagram of polarized light as it propagates within a birefringent crystal layer.
Fig. 8 is a schematic diagram of polarized light as it propagates within an outcoupling grating.
Fig. 9 is a schematic structural diagram of an optical-mechanical system according to a second embodiment of the present application.
Fig. 10 is a schematic structural diagram of an optical-mechanical system according to a third embodiment of the present application.
Fig. 11 is a schematic structural diagram of an optical-mechanical system according to a fourth 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. It should be noted that, in the drawing, R represents an edge light beam of incident light, S represents S polarized light, P represents P polarized light, and L represents an coupled-out light beam coupled out from the coupling grating, which is not described in detail below.
First embodiment
Referring to fig. 1, the present embodiment provides an optical-mechanical system 10, where the optical-mechanical system 10 includes at least one illumination system 20, a spatial light modulator 30, a polarizer 40, 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 to be displayed after passing through the polarizer 40.
Specifically, the illumination system 20 includes the optical waveguide 100, the coupling-in device 200, and the coupling-out grating 300, and the coupling-in device 200 and the coupling-out grating 300 are disposed on the optical waveguide 100.
Further, the illumination system 20 may further include a light source 400, and the light source 400 is configured to generate incident light with a single polarization state, wherein the incident light with the single polarization state refers to S-polarized light or P-polarized light. In one embodiment, the light source 400 may be a linearly polarized laser. In another embodiment, the light source 400 may include an LED light source 400 or other type of laser and a polarizer, and the light beam emitted from the LED light source 400 or other type of laser passes through the polarizer and is collimated and homogenized to form a uniform light spot as the incident light with a single polarization state. In this embodiment, the incident light emitted from the light source 400 is S-polarized light. The incident light emitted from the light source 400 may be white light or monochromatic light, and is not limited herein.
The optical waveguide 100 includes a first surface 110, a second surface 120 and an end surface 130 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 transmit light. The incoupling means 200 and the outcoupling grating 300 are both arranged on the second surface 120, i.e. the incoupling means 200 and the outcoupling grating 300 are arranged on the same side surface of the optical waveguide 100, the end surface 130 is connected between the first surface 110 and the second surface 120 and is substantially perpendicular to the first surface 110 and the second surface 120. Wherein the optical waveguide 100 comprises a coupling-in region and a coupling-out region, at which the first surface 110 and the second surface 120 are formed at the same time.
The incoupling device 200 is disposed in the incoupling region, and is configured to receive an incident light with a single polarization state 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 from the incoupling region to the outcoupling region. 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. 2, the incoupling device 200 includes a prism 210, where the prism 210 may be a triangular prism 210, a refractive index of the prism 210 may be greater than 1, the prism 210 is disposed on the second surface 120 of the incoupling area, 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 incoupling area, so that the incident light entering the incoupling area is totally reflected on the surface of the optical waveguide 100. Further, the back surface may be further provided with a light absorbing layer 220, and the light absorbing 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. 3, the coupling-in device 200 may also adopt a surface relief grating/holographic grating manner, specifically, a layer of surface relief grating 240 is processed on the second surface 120 of the coupling-in region as the coupling-in device 200, and the width of the grating region is the width of light traveling after a total reflection by 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 orders of diffraction propagate in the direction of the coupling-out zone at a specific diffraction angle such that T1Order diffraction or T-1The order diffraction may be totally reflected within the optical waveguide 100 and into the outcoupling region. Note that, the control T1Order diffraction or T-1The diffraction angle of the order diffraction can be controlledGrating parameters of the surface relief grating 240.
In another embodiment, as shown in fig. 4, the coupling-in device 200 may also be configured in a wedge-angle total reflection manner, the end surface 130 of the optical waveguide 100 in the coupling-in area is configured as an inclined surface, 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, and thus the light can reach the outcoupling region via total reflection, and the slope may be 30 ° to 60 °, for example.
Referring to fig. 1 and 5, the optical waveguide 100 may be made of flat glass with refractive index n, thickness d, and critical angle θ of total reflection0＝arcsin(naN) in which naThe larger the refractive index of the optical waveguide 100 is, the smaller the critical angle of total reflection is, which is the refractive index of air, and thus the range of angles within which light can be totally reflected in the optical waveguide 100 is increased, which increases the degree of freedom in design. The total reflection angle has a large influence on the outcoupling efficiency, taking the refractive index of the optical waveguide 100 as 1.71, the wavelength of the incident light as 520nm, and the outcoupling grating 300 as a straight grating as an example, the total reflection critical angle at this time is 37.8 °, since the illumination light has a high requirement on uniformity, when the uniformity is limited to a relatively high level (2%), the smaller the total reflection angle is, the higher the total outcoupling efficiency is, and the larger the total reflection angle is, the faster the total outcoupling efficiency decreases. The choice of the angle of total reflection close to the critical angle thus makes it possible to obtain a higher coupling-out efficiency, on the basis of which the refractive index of the optical waveguide 100 can be chosen reasonably.
The coupling-out grating 300 is disposed in the coupling-out region, and the coupling-out grating 300 is used for coupling out the incident light transmitted by the optical waveguide 100 to form the illumination light emitted perpendicularly to the coupling-out region. Specifically, the incident light enters the coupling-out region after being totally reflected once or multiple times in the optical waveguide 100, and is emitted through the coupling-out grating 300 to form the illumination light.
In order to avoid the formation of dark spots on subsequent entry into the spatial light modulator 30, it is desirable to make the illumination light spot formed a continuous spot. When the incident light beam is in the optical waveguide 100 internal angle of total reflection theta1And the light propagates forwards, and the polarization state is kept unchanged after the light is totally reflected when the incident light beam is p light or s light according to the Fresnel reflection law. After the totally reflected light beam enters the coupling-out region, a plurality of light beams are elastically coupled out in the coupling-out region for a plurality of times, and when the light beams totally reflected in the optical waveguide 100 have the section width l on the waveguide surfacebThe same distance l as the incident light travels through a total reflection in the optical waveguide 100, i.e., l ═ 2d × tan θ1In the meantime, there is no gap between the outgoing light beams exiting from the outcoupling region, and the size of the outcoupling light beam is equal to that of the outcoupling region, so that the multiple light beams outcoupled from the outcoupling grating 300 can form a complete and continuous illumination light spot. It is noted that if l < 2d tan θ1Partial overlapping can be formed among a plurality of emergent light beams emitted from the coupling-out region, although continuous illuminating light spots can also be formed, the formed illuminating light has certain light and shade distribution, and the contrast of subsequent imaging can be influenced.
The coupled grating 300 is a surface relief grating, which can be mass-produced by using a nano-imprinting process, and has a significant advantage in mass production and reliability 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 favorable for forming stable and uniform illumination light. The coupling-out grating 300 may be a straight grating, an inclined grating, a blazed grating, or the like, and is not limited herein.
When the incident light travels in the optical waveguide 100, a part of the light is coupled out from the coupling-out grating 300 in the coupling-out region, and the remaining light is totally reflected continuously along the traveling direction, at this time, the brightness of the incident light beam is gradually reduced, and the incident light beam is coupled out from the subsequent coupling-out grating 300 to form a plurality of light beams, and the brightness of the coupling-out light beams L emitted from the gratings at different positions has a certain difference, which affects the imaging quality of the subsequent spatial light modulator 30. Therefore, the grating parameters of the outcoupling grating 300 need to be designed reasonably so that the light intensity of the multiple light beams outcoupled from the outcoupling grating 300 is uniform.
In a more specific embodiment, referring to fig. 1 again, the outcoupling grating 300 includes a plurality of outcoupling regions 310, the outcoupling regions 310 are arranged side by side along the traveling direction of the incident light in the optical waveguide 100, and at least one grating parameter of each grating region is not equal, so that the illumination light emitted from different outcoupling regions 310 has the same intensity. The reason is that: the grating parameters may include grating parameters including grating period, grating duty cycle, grating depth, tilt angle, and refractive index. For example: the grating parameters in the same outcoupling region 310 may be kept fixed, and the grating periods may be different in different outcoupling regions 310, so that the illumination light exiting from different outcoupling regions 310 has the same intensity, and the grating period of the outcoupling region 310 farther from the incoupling means 200 is smaller than the grating period of the outcoupling region 310 closer to the incoupling means 200; alternatively, the grating duty cycle of the outcoupling region 310 that is further from the incoupling means 200 is larger than the grating duty cycle of the outcoupling region 310 that is closer to the incoupling means 200; or, the grating depth of the coupling-out region 310 farther from the coupling-in device 200 is larger than the grating depth of the coupling-out region 310 closer to the coupling-in device 200, etc., and is not particularly limited herein.
Illustratively, in the present embodiment, the outcoupling grating 300 includes 4 outcoupling regions 310, the 4 outcoupling regions 310 are arranged side by side along the traveling direction of the incident light in the optical waveguide 100, and the grating period of the outcoupling region 310 farther from the incoupling device 200 is smaller than that of the outcoupling region 310 closer to the incoupling device 200.
In another more specific embodiment, the outcoupling grating 300 may not be divided into the outcoupling region 310, and at least one grating parameter of the outcoupling grating 300 is gradually changed along the traveling direction of the incident light in the optical waveguide 100. Specifically, the setting may be performed in the following manner: the grating period is smaller in regions further from the incoupling device 200 than in regions closer to the incoupling device 200; alternatively, the grating duty cycle is greater in regions further from the incoupling means 200 than in regions closer to the incoupling means 200; alternatively, the grating depth is greater in regions further from the incoupling device 200 than in regions closer to the incoupling device 200.
Both of the above two arrangements can make the illumination light beams emitted from the coupling grating 300 have the same light intensity, so that the imaging quality of the image light formed by the subsequent spatial light modulator 30 can be ensured.
The illumination light emitted from the coupling-out grating 300 of the coupling-out region is emitted in a form perpendicular to the second surface 120 and is 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 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, the spatial light modulator 30 is disposed corresponding to the light coupling grating 300, the illumination light can 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 to form image light and emit 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.
Wherein part of the incident light reaches the end surface 130 of the optical waveguide 100 during the traveling of the incident light in the optical waveguide 100, in order to prevent the incident light from escaping from the end surface 130 to cause thermal effect, the end surface 130 may be provided with a light absorbing layer for absorbing the incident light incident on the end surface 130, and the light absorbing layer may be light absorbing glue.
In this embodiment, the polarizer 40 is disposed on a side of the optical waveguide 100 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 exit light path of the image light, when the image light passes through the polarizer 40, the polarizer 40 can 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.
Since the incident light is S-polarized light, the polarization state of the incident light is not changed and the light is not S-polarized while propagating 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 can 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 then enter the projection lens 50.
In this embodiment, as shown in fig. 6, the grating structure of the outcoupling grating 300 has a plurality of grooves 301, the grooves 301 are filled with a birefringent crystal layer 302, which has anisotropy, and the birefringent crystal has different dielectric constants, conductivities, thermal expansion coefficients, and the like along different directions, so that the optical properties of the birefringent crystal also have anisotropy, and further, the propagation speed, the propagation direction of the light vector (energy vector), and the wave vector of the light propagating or vibrating along different directions are different. When a light beam is incident on the photorefractive crystal, a birefringence phenomenon occurs. One of the beams has the same propagation characteristics as in an isotropic medium, and follows the law of refraction, called ordinary ray, and the other does not follow the law of refraction, called extraordinary ray.
In the birefringent crystal, there is a specific direction along which light is incident without birefringence, this direction is the optical axis of the crystal, and the uniaxial crystal is a birefringent crystal with an optical axis, and the uniaxial crystal has a specific optical axis, so that the refractive index is represented as an ellipsoid, as shown in fig. 7: three axes of the ellipsoid are three director vectors, the optical axis of the birefringent crystal in the upper figure is along the vertical direction, and when the direction of the electric field vector of the incident light is consistent with the direction of the three axes, the refractive index is neMeanwhile, the birefringence effect occurs, the beam is an extraordinary ray, when the electric field vector direction of the incident light is perpendicular to the optical axis, the refractive index is noNo birefringence effect occurs, and the light beam is ordinary light.
Referring to fig. 8, since the s-polarized optical electric field vector is always perpendicular to the incident surface and the p-polarized optical electric field vector is parallel to the incident surface, the optic axis direction of the birefringent crystal layer 302 can be adjusted to be the same as the optic axis direction of the s-polarized optical electric field vector, and the refractive index n felt by the s-polarized light at the birefringent crystal layer 302 at this time iseRefraction sensed by p-polarized lightRate of no. The refractive index of the grating material is close to noIn this case, the diffraction effect of the p-polarized light at the coupling grating 300 is weak, and thus the emission efficiency of the p-polarized light can be improved, and the display luminance of the image light can be improved.
In this embodiment, when the p-polarized light in the image light enters the birefringent crystal layer 302, the diffraction effect of the p-polarized light at the outcoupling grating 300 is very weak, the 0-order diffraction exit efficiency of the p-polarized light is high, and the non-0-order diffraction-order light generated when the p-polarized light passes through the outcoupling grating 300 can be weakened, so that the interference of stray orders on other pixels is reduced, and the contrast is improved. More preferably, the refractive index of the grating 300 is coupled to the ordinary refractive index n of the birefringent crystal layer 3020In this case, the outcoupling grating 300 is equivalent to a flat glass for p-polarized light, and the p-polarized light can completely penetrate the outcoupling grating 300, thereby further improving the emission efficiency.
The birefringent crystal layer 302 is provided, so that when the illumination light is coupled out from the outcoupling grating 300, the normal coupling-out of the s-polarized light is not affected, and the illumination brightness of the illumination light is not affected.
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 polarizing plate, 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 in this embodiment adopts the optical waveguide 100 and the grating structure to emit the illumination light, and the overall volume and weight are small, 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. Meanwhile, due to the fact that the birefringent crystal layer is arranged, the emitting efficiency of image light is improved, and the contrast is improved.
Second embodiment
Referring to fig. 9, the present embodiment provides an optical-mechanical system 10, which has substantially the same structure as the optical-mechanical system 10 in the first embodiment, and the same parts are not repeated, and reference may be made to the related contents of the first embodiment, and only different parts are described below.
In this embodiment, the polarizer 40 is a reflective polarizer that can transmit P-polarized light and reflect S-polarized light. Meanwhile, the end surface 130 is not provided with the absorption layer 140, but provided with the reflection layer 150, and the reflection layer 150 may be implemented by plating a total reflection film on the end surface 130 or by polishing the end surface 130.
The benefits of this embodiment are: when the incident light reaches the end surface 130 of the optical waveguide 100, the incident light is reflected back to the optical waveguide 100 by the reflective layer 150, and is further totally reflected in the optical waveguide 100, and is further coupled out from the coupling-out grating 300, so that the light can be collected and the coupling-out efficiency can be improved. Meanwhile, the S-polarized light reflected by the spatial light modulator 30 is transmitted through the optical waveguide 100 and then reflected back to the optical waveguide 100 by the polarizer 40, so that the light can be further collected and the coupling efficiency can be improved.
Third embodiment
Referring to fig. 10, the present embodiment provides an optical-mechanical system 10, which has substantially the same structure as the optical-mechanical system 10 in the first embodiment, and the same parts are not repeated, and reference may be made to the related contents of the first embodiment, and only different parts are described below.
In this embodiment, the optical waveguide 100 further includes a reflective region located at a side of the coupling-out region away from the coupling-in region, the end surface 130 is located at the reflective region, and the reflective gratings 500 are disposed on the first surface 110 and the second surface 120 of the reflective region.
The benefits of this embodiment are: when the incident light passes through the coupling-out region during the propagation of the incident light in the optical waveguide 100, a part of the incident light enters the reflection region and continues to be totally reflected on the first surface 110 and the second surface 120 of the reflection region, and due to the arrangement of the reflection grating 500, the reflection grating 500 can reflect the part of the light toward the coupling-out grating 300 of the coupling-out region, so that the part of the light can be reused, and the coupling-out efficiency is improved. Compared with the second embodiment, since the path of the light reflected by the reflective grating 500 can be precisely controlled by precisely controlling the grating parameters of the reflective grating 500, the light can be uniformly distributed when being reflected back to the outcoupling grating 300, the phenomenon of brightening the dark area in the spatial light modulator 30 is avoided, and the contrast of the image light is improved.
Of course, it should be noted that the absorption layer 140 may be replaced by the reflection layer 150 at this time, and the arrangement manner may refer to the second embodiment.
Fourth embodiment
Referring to fig. 11, the present embodiment provides an optical-mechanical system 10, which has substantially the same structure as the optical-mechanical system 10 in the first embodiment, and the same parts are not repeated, and reference may be made to the related contents of the first embodiment, and only different parts are described below.
In this embodiment, there are a plurality of illumination systems 20, the incoupling device 200 in each illumination system 20 is used for receiving incident light of one color and emitting the incident light from the outcoupling grating 300 to form monochromatic illumination light, and the outcoupling grating 300 in each illumination system 20 is correspondingly arranged so that the monochromatic illumination light formed by each illumination system 20 is incident on the spatial light modulator 30. Specifically, the number of the illumination systems 20 is three, and the illumination systems respectively receive incident lights of red, green and blue colors. The optical waveguides 100 of the three illumination systems 20 may be arranged adjacently or at intervals, and the light coupling gratings 300 of the three illumination systems 20 have the same area and are arranged completely correspondingly, so that the monochromatic illumination light formed by each illumination system 20 can be irradiated into the spatial light modulator 30.
The working principle and the arrangement mode of each lighting system 20 can refer to the foregoing embodiments, and are not described herein again.
In this embodiment, the coupling-in device 200 of the illumination system 20 adopts a grating structure, the light sources 400 are incident on the coupling-in device 200 in a manner perpendicular to the second surface 120, the plurality of light sources 400 may be arranged side by side, and the coupling-in devices 200 of the plurality of illumination systems 20 are staggered from each other and arranged corresponding to the plurality of light sources 400. It is understood that, in some other embodiments, the incident light may also be coupled in by using the prism 210 or a total reflection manner at a wedge angle, which may be specifically referred to in the first embodiment.
It should be noted that the number of the lighting systems 20 may also be two or more than three according to actual needs, and the embodiment is not particularly limited.
The optical-mechanical system 10 provided by this embodiment can provide image light modulation of three primary colors, and by controlling the light source 400 to be turned on or off in a time sequence, monochrome modulation of the image light can be realized and a color image can be formed on a projection surface, and the overall volume and weight of the apparatus are small, and the apparatus is suitable for being applied to an AR apparatus. Meanwhile, the double-refraction crystal layer is arranged, so that the emergent efficiency of image light is improved, and the contrast is improved.
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 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 (11)
1. An illumination system, characterized in that the illumination system comprises:
an optical waveguide comprising a coupling-in region and a coupling-out region;
the coupling-in device is arranged in the coupling-in area and used for receiving incident light with a single polarization state and coupling the incident light into the optical waveguide so as to enable the incident light to be totally reflected in the optical waveguide; and
the light guide is arranged in the light guide body, the light guide body is arranged in the light guide body, and the light guide body is arranged in the light guide body.
2. The illumination system of claim 1 wherein the refractive index of the outcoupling grating and the ordinary refractive index n of the birefringent crystal layer0Are equal.
3. An illumination system according to claim 1, characterized in that the thickness of the optical waveguide satisfies l-2 d tan θ1Where l is a distance traveled by the incident light through a total reflection in the optical waveguide, d is a thickness of the optical waveguide, and θ1Is the angle of total reflection.
4. The illumination system of claim 1, wherein the outcoupling grating comprises a plurality of outcoupling regions arranged side by side, and at least one grating parameter of each outcoupling region is unequal such that illumination light exiting from different outcoupling regions has the same intensity, the grating parameters comprising grating period, grating duty cycle, grating depth, tilt angle, and refractive index;
wherein each of the coupling-out regions has a width equal to a distance that the incident light travels through one total reflection within the optical waveguide.
5. The illumination system according to claim 1, wherein at least one grating parameter of the out-coupling grating is arranged gradually along the travelling direction of the incident light within the optical waveguide, the grating parameter comprising grating period, grating duty cycle, grating depth, tilt angle and refractive index.
6. An illumination system as claimed in claim 4 or 5, characterized in that the optical waveguide has a first and a second opposite surface and an end face connected between the first and the second surface, which end face is situated at the end of the optical waveguide remote from the coupling-in region, which end face is provided with a light-absorbing or reflecting layer.
7. The illumination system according to claim 6, wherein the optical waveguide further comprises a reflective region located on a side of the coupling-out region away from the coupling-in region, the end surface is located in the reflective region, and the first surface and the second surface of the reflective region are both provided with reflective gratings.
8. An illumination system according to any one of claims 1-3, characterized in that the incoupling means comprises a prism arranged at a surface of the incoupling zone, said prism having an entrance face for receiving incident light and a back face opposite to the entrance face, said entrance face being arranged to feed into the incoupling zone for total reflection at the surface of the optical waveguide of the incident light entering the incoupling zone, said back face being provided with a light absorbing layer.
9. An opto-mechanical system comprising at least one illumination system according to any one of claims 1 to 8, a spatial light modulator for receiving and modulating illumination light emitted from the illumination system to form image light and transmitting the coupled grating and the optical waveguide, a polarizer for filtering the image light, and a projection lens for displaying the image light transmitted through the polarizer, wherein the projection lens is located on a side of the optical waveguide away from the spatial light modulator.
10. The opto-mechanical system of claim 9, wherein the polarizer is an absorbing polarizer or a reflective polarizer.
11. The opto-mechanical system of claim 9, wherein the illumination system is plural, the incoupling device in each illumination system is configured to receive an incident light of one color and emit the incident light from the incoupling grating to form a monochromatic illumination light, and the incoupling grating in each illumination system is correspondingly arranged so that the monochromatic illumination light formed by each illumination system is incident on the spatial light modulator.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2024066177A1 (en) * | 2022-09-27 | 2024-04-04 | 苏州苏大维格科技集团股份有限公司 | Polarizing thin film and manufacturing method therefor, optical waveguide lens, and display apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2024066177A1 (en) * | 2022-09-27 | 2024-04-04 | 苏州苏大维格科技集团股份有限公司 | Polarizing thin film and manufacturing method therefor, optical waveguide lens, and display apparatus |
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