CN117761905A - Optical combiner and near-to-eye display device - Google Patents

Abstract

The invention discloses an optical combiner and near-to-eye display equipment, wherein the optical combiner comprises an optical waveguide module and a polarization modulation module, wherein the optical waveguide comprises a coupling-in module, an optical waveguide and a coupling-out module, and the polarization modulation module is used for modulating unpolarized light with different emergence angles and any polarization directions emitted from an optical machine module into polarized light with the same polarization direction, and the polarized light is incident into the coupling-in module at the same angle, is transmitted through the optical waveguide and is emitted to human eyes through the coupling-out module. The optical combiner provided by the embodiment converts the incident unpolarized light into the light with the same polarization state by using the polarization modulation module, thereby improving the utilization ratio of the optical waveguide to the incident light. The power consumption is reduced due to the increase in the light energy utilization rate, and the brightness of the virtual image incident into the eyes of the user is increased.

Description

Optical combiner and near-to-eye display device

Technical Field

The invention relates to the technical field of near-eye display equipment, in particular to an optical combiner and near-eye display equipment.

Background

The near-eye display device generally comprises an optical-mechanical module and an optical combiner, wherein the optical-mechanical module provides a light source signal of a virtual image, and the optical combiner receives the light source signal and transmits the light source signal to the human eye.

At present, an optical machine module in a near-eye display device commonly uses a micro-LED, LCoS, DLP screen as an image source, a light source signal emitted by the optical machine module is unpolarized light, and a diffraction grating adopted in a current optical waveguide only has higher diffraction efficiency on one polarized light or incident light under one polarized condition, so that the light source signal needs to be modulated into specified polarized light, and the utilization rate of the optical waveguide on the energy of the incident light is improved.

Disclosure of Invention

In view of the above-mentioned shortcomings in the related art, an object of the present invention is to provide an optical combiner and a near-eye display device, which overcome the defect of low utilization of incident light energy by an optical waveguide.

The technical scheme adopted for solving the technical problems is as follows:

in a first aspect, the present embodiment discloses an optical combiner, including:

at least one group of polarization modulation modules consisting of diffraction gratings of different types; the polarization modulation module is arranged on an optical path of the unpolarized light output by the optical machine module and is used for modulating the unpolarized light with different emergence angles and any polarization directions emitted by the optical machine module into polarized light with the same polarization direction and the same emergence angle;

at least one set of optical waveguide modules comprising a coupling-in module, an optical waveguide and a coupling-out module; the coupling-in module is arranged on the surface of the optical waveguide and is used for receiving polarized light emitted from the polarization modulation module and coupling the received polarized light into the optical waveguide; the coupling-out module is arranged on the surface of the optical waveguide and is used for coupling out polarized light in the optical waveguide.

Optionally, the polarization modulation module includes at least one liquid crystal polarizer holographic grating and at least one volume holographic grating.

Optionally, the optical waveguide module further comprises a relay module; the optical waveguide is used for turning the propagation direction of the optical signal coupled into the optical waveguide from the coupling-in module, so as to realize two-dimensional pupil expansion;

the coupling-in module, the coupling-out module and/or the relay module are/is arranged on the surface of the same side of the optical waveguide; alternatively, the in-coupling module, the out-coupling module and/or the relay module are provided on surfaces of different sides of the optical waveguide.

Optionally, the polarization modulation module further includes: a 1/4 wave plate;

the 1/4 wave plate is used for modulating circularly polarized light emitted from the volume holographic grating into linearly polarized light.

Optionally, the in-coupling module, the out-coupling module and/or the relay module is any one of a liquid crystal polarizer holographic grating, a volume holographic grating, a surface relief grating and a super surface.

Optionally, the polarization modulation modules are multiple groups, and the liquid crystal polarization body holographic gratings and the body holographic gratings are sequentially arranged at intervals; wherein, the polarization modulation modules of each group are respectively used for modulating the unpolarized light of different wave bands.

Optionally, the polarization modulation modules and the optical waveguide modules are multiple groups, and the polarization modulation modules of each group are sequentially overlapped from top to bottom to form a combined polarization modulation module; each group of optical waveguide modules are sequentially overlapped and arranged from top to bottom to form a combined optical transmission module, and the combined polarization modulation module is positioned above the coupling-in module in the combined optical transmission module;

the combined polarization modulation module sequentially carries out polarization modulation on light of corresponding wave bands in the incident unpolarized light, then transmits the modulated polarized light of each wave band to each group of optical waveguide modules, couples the modulated polarized light into the coupling-in modules of the corresponding wave bands in each group of optical waveguide modules respectively, and couples the polarized light out of the coupling-out modules of the corresponding wave bands after transmitting the polarized light in the optical waveguides of the corresponding wave bands.

Optionally, the polarization modulation modules and the optical waveguide modules are multiple groups, and a group of polarization modulation modules and a group of optical waveguide modules form a group of optical modulation modules; each group of light modulation modules are sequentially arranged from top to bottom, and the polarization modulation modules are positioned above each coupling-in module in the optical waveguide module;

the polarization modulation modules in each group of light modulation modules sequentially carry out polarization modulation on light with corresponding wave bands in the incident unpolarized light, the light is coupled into each group of light waveguides through the coupling-in modules with corresponding wave bands, and the light is transmitted in the light waveguides with corresponding wave bands and is coupled out from the coupling-out modules with corresponding wave bands after the transmission direction is changed by the relay modules with corresponding wave bands.

Optionally, the in-coupling module, the out-coupling module and/or the relay module is any one of a liquid crystal polarizer holographic grating, a volume holographic grating, a surface relief grating and a super surface.

In a second aspect, the present embodiment further provides a near-eye display device, including: the optical combiner.

The beneficial effects are that:

the embodiment discloses an optical combiner and near-eye display equipment, wherein the optical combiner comprises at least one group of polarization modulation modules formed by diffraction gratings of different types; the polarization modulation module is arranged on an optical path of the unpolarized light output by the optical machine module and is used for modulating the unpolarized light with different emergence angles and any polarization directions emitted by the optical machine module into polarized light with the same polarization direction and the same emergence angle; at least one set of optical waveguide modules comprising a coupling-in module, an optical waveguide and a coupling-out module; the coupling-in module is arranged on the surface of the optical waveguide and is used for receiving polarized light emitted from the polarization modulation module and coupling the received polarized light into the optical waveguide; the coupling-out module is arranged on the surface of the optical waveguide and is used for coupling out polarized light in the optical waveguide. The optical combiner provided by the embodiment converts incident unpolarized light into light with the same polarization rotation direction by using different types of diffraction gratings, thereby improving the utilization ratio of the optical waveguide to the incident light. The power consumption is reduced due to the increase in the light energy utilization rate, and the brightness of the virtual image incident into the eyes of the user is increased.

Drawings

FIG. 1 is a schematic diagram of a prior art liquid crystal polarizer holographic grating;

FIG. 2 is a schematic diagram of diffraction characteristics of a prior art liquid crystal polarizer holographic grating;

fig. 3a and 3b are schematic diagrams of diffraction characteristics of a reflective volume hologram grating and a transmissive volume hologram grating, respectively;

FIG. 4 is a schematic diagram of an optical combiner according to a first embodiment of the present invention;

FIG. 5 is a schematic diagram of a second embodiment of an optical combiner according to the present invention;

FIG. 6 is a schematic diagram of a third embodiment of an optical combiner according to the present invention;

fig. 7 is a schematic structural diagram of a fourth embodiment of an optical combiner provided by the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.

The near-eye display device generally comprises an optical-mechanical module and an optical combiner, wherein the optical combiner comprises an optical waveguide combiner, a free-form surface and a Birdbath, the optical waveguide combiner comprises a geometric optical waveguide and a diffraction optical waveguide, and the diffraction optical waveguide comprises an in-coupling module, an out-coupling module and/or a relay module. The optical machine module is used for providing a light source signal of the virtual image; the coupling-in module receives the light source signal provided by the optical machine module and couples the light source signal into the optical waveguide, the optical waveguide performs total reflection transmission on the input light, and the coupling-out module couples the light in the optical waveguide to the human eye. In general, in order to enlarge the exit pupil, the diffractive optical waveguide will also comprise a relay module, which turns the direction of transmission of the optical signal coupled into the waveguide from the coupling-in module. The coupling-in module, the coupling-out module and the relay module comprise surface relief gratings, volume Holographic Gratings (VHG), liquid crystal polarizer volume holographic gratings and super surfaces.

Further, surface relief gratings are commonly manufactured in bulk using nanoimprint processes, both cost and performance of which depend on the manufacture of high precision molds. While Volume Holographic Gratings (VHG) can be mass manufactured at lower cost through exposure and roll-to-roll processes, while also enabling large area fabrication. However, the Volume Hologram Grating (VHG) has a bragg effect, and thus its angular bandwidth and wavelength bandwidth are narrow, which is mainly limited by the degree of refractive index modulation of the material. Since Polymer Dispersed Liquid Crystal (PDLC) materials have a higher refractive index modulation degree than other volume hologram recording materials, liquid crystal polarizer holographic gratings (PVGs) based on polymer dispersed liquid crystals are currently being studied.

Currently, an optical-mechanical module used in a near-eye display device usually adopts a micro-LED, LCoS, DLP screen as an image source, and an emergent light signal of the micro-LED, LCoS, DLP screen is unpolarized. However, for surface relief gratings, it is common for incident light of one polarization state of TE or TM (which can be divided into TE polarization, TM polarization and mixed polarization according to the directional relation of the electric field component and the magnetic field component to the wave vector in the light beam incident on the surface relief grating) to have higher diffraction efficiency. In addition, PVG generally diffracts only one polarization direction of left-circularly polarized light or right-circularly polarized light. Therefore, the energy utilization rate of the optical waveguide can be further improved by modulating the signal emitted by the optical machine module into a specified polarization state no matter the surface relief grating or the liquid crystal polarizer holographic grating.

The current method for improving the energy utilization rate of the optical waveguide is generally to add a polarization modulation device in the light beam emitted by the optical machine module, however, the current commonly used polarization modulation device, such as a polarization beam splitting prism, a polaroid and a prism combination, has the defects of large volume or 50% loss of light power, which limits the application of the current commonly used polarization modulation device in near-eye display equipment, leads to low energy utilization rate of the incident light of the existing optical waveguide, and is particularly unfavorable for meeting the polarization modulation requirements of the near-eye display fields such as AR and the like on small volume and high light energy utilization rate.

In order to solve the problem of low utilization of optical efficiency in an optical waveguide, the present embodiment provides an optical combiner including: the optical waveguide module comprises a coupling-in module, an optical waveguide and a coupling-out module. The coupling-in module couples the polarized light sent out by the polarization modulation module into the optical waveguide and transmits the polarized light, and the coupling-out module couples the light transmitted in the optical waveguide out.

According to the optical combiner provided by the embodiment, the polarization modulation modules formed by the diffraction gratings of different types are utilized to adjust the unpolarized light emitted by the optical machine module, so that the utilization rate of the optical waveguide to the incident light is improved, the power consumption is reduced, and the polarization modulation modules formed by the diffraction gratings are small in size, so that the requirements of the near-to-eye display equipment on light weight and high energy efficiency can be met.

Further, the polarization modulation module provided in this embodiment is formed by combining diffraction gratings of different types, where the diffraction grating includes: the diffraction grating disclosed in this embodiment may be obtained by combining a liquid crystal polarizing body hologram grating and a body hologram grating. The polarization modulation modules can be one group or multiple groups.

Specifically, as shown in FIG. 1, a liquid crystal polarizer holographic grating (PVG) is periodically distributed by rotation of the optical axis of liquid crystal molecules in the x-direction and torsion in the y-direction, with periods of respectively，/>. With this structure, the equivalent period of the liquid crystal polarizer holographic grating (PVG) is +.>Wherein->And grating(s)Inclination angle of +.>，/>. Since the liquid crystal polarizing hologram grating (PVG) has an anisotropic refractive index distribution, it has a characteristic of selectively responding to the polarization of incident light. At the same time, it also has the characteristic of VHG, i.e. when the angle of incidence of the incident beam is +.>Wavelength->Bragg diffraction will occur when the bragg condition is satisfied, and can be expressed as:

，

wherein,is the average refractive index of the liquid crystal polarizer holographic grating (PVG).

Further, liquid crystal polarizer holographic gratings (PVGs) are classified into transmissive and reflective types, in which the diffracted and incident beams are reflected on the same side of the grating and transmitted on opposite sides of the grating. When the bragg condition is satisfied, the diffraction angle of the diffracted beam can be calculated by the following equation,

，

；

under non-bragg conditions, the diffraction angle of the diffracted beam may be calculated by,

。

the polarization handedness of the diffracted beams of light is shown in fig. 2 for both reflective and transmissive liquid crystal polarizer holographic gratings (PVGs). Diffraction occurs when the incident circularly polarized light and the liquid crystal molecules have the same helical twist direction, and the polarization direction of the diffracted light is reversed. The incident circularly polarized light and the liquid crystal molecules directly penetrate when the spiral directions of the incident circularly polarized light and the liquid crystal molecules are opposite. However, for reflective liquid crystal polarizer holographic gratings (PVGs), the diffracted beam maintains the same polarization rotation as the incident beam, since reflection introduces a primary polarization rotation reversal.

As shown in fig. 3a and 3b, volume Hologram Gratings (VHG) can be classified into two types according to propagation directions of incident light and diffracted light. One type is a reflective Volume Holographic Grating (VHG), which has the diffraction characteristic that the incident light and the diffracted light are on the same side of the grating; the second type is a transmissive Volume Holographic Grating (VHG), in which incident light and diffracted light are on either side of the grating. In terms of diffraction characteristics, a Volume Holographic Grating (VHG) is mainly characterized by its highly efficient bragg single-order diffraction characteristics. Specifically, the Volume Hologram Grating (VHG) can eliminate the remaining diffraction orders other than +1 order (or-1 order) at a specific combination of an incident angle, wavelength, grating period, and grating tilt angle, that is, diffraction energy is almost entirely concentrated in +1 diffraction order or-1 diffraction order. And the corresponding grating parameter combinations are called bragg conditions. Assuming that the equivalent refractive index of the recording medium isAnd is equal to the surrounding refractive index, the Bragg condition can be expressed as:

，

wherein,is the inclination angle of the grating +.>Is the angle of incidence. Volume Holographic Gratings (VHGs) can have diffraction efficiencies that meet Bragg conditionsNear 100%, if incident light->Grating parameters->、/>The diffraction efficiency is rapidly reduced due to the deviation from the Bragg condition, so that the Volume Holographic Grating (VHG) has good wavelength and angle selectivity, and can be used as a frequency-selecting and filtering device with excellent performance.

In this embodiment, the combination grating device of the liquid crystal polarization volume holographic grating (PVG) and the Volume Holographic Grating (VHG) is used to convert the non-polarized light incident by the optical machine module into the light beam with the same polarization rotation direction, so that the light energy utilization rate of the optical machine module can be improved, and the power consumption of the device can be reduced.

The optical combiner and the near-eye display device disclosed in this embodiment are further described below with reference to the accompanying drawings.

The present embodiment discloses an optical combiner, comprising:

at least one set of optical waveguide modules; in particular embodiments, the optical waveguide module may have one or more groups.

The polarization modulation module is arranged between the optical machine module and the coupling-in module and is used for modulating unpolarized light with different emergence angles and any polarization directions emitted by the optical machine module into polarized light with the same polarization direction and transmitting the polarized light to the coupling-in module at the same angle.

In order to achieve modulation of unpolarized light of different wavebands, the polarization modulation modules may have one or more groups in particular embodiments.

The optical waveguide module comprises a coupling-in module, an optical waveguide and a coupling-out module; the coupling-in module is arranged on the surface of the optical waveguide and is used for receiving polarized light emitted from the polarization modulation module and coupling the received polarized light into the optical waveguide; the coupling-out module is arranged on the surface of the optical waveguide and is used for coupling out polarized light in the optical waveguide. For polarized light of different wavebands, a plurality of in-coupling modules and out-coupling modules can be correspondingly arranged.

Further, the optical waveguide module further comprises a relay module; the relay module is used for turning the propagation direction of the optical signal coupled into the optical waveguide from the coupling-in module, so as to realize two-dimensional pupil expansion. The relay module can be a relay coupling-in grating or a relay coupling-out grating.

The coupling-in module, the coupling-out module and/or the relay module are/is arranged on the surface of the same side of the optical waveguide; alternatively, the in-coupling module, the out-coupling module and/or the relay module are provided on surfaces of different sides of the optical waveguide.

Further, a protective cover plate is arranged on the periphery of the optical combiner. An adhesive layer is also provided between the protective cover plate and the optical waveguide module.

The light-emitting assembly and the fixing assembly are arranged in the light-machine module, the fixing assembly is used for fixing the light-emitting assembly, the light-emitting assembly is used for emitting light beams, and the light beams are unpolarized light.

The optical machine module is arranged above the polarization modulation module, wherein the emitted unpolarized light is received by the polarization modulation module positioned below, and the rotation angle and the incidence angle of the received unpolarized light are adjusted by the polarization modulation module. The regulated polarized light transmitted from the polarization modulation module is incident into the coupling-in module, the coupling-in module receives the regulated polarized light, couples the polarized light into the optical waveguide positioned below, performs total reflection transmission in the optical waveguide, and is coupled out from the coupling-out module and then transmitted into human eyes positioned above the coupling-out module.

The polarization modulation module is composed of different diffraction gratings to modulate received unpolarized light into polarized light and modulate unpolarized light with different emergence angles and different polarization directions into polarized light with the same polarization direction and the same angle. The diffraction angle can be changed by combining the setting of grating parameters. In one embodiment, the polarization modulation module includes a liquid crystal polarization volume hologram and a volume hologram.

The optical combiner of the present invention will be described in more detail below with specific application examples of the optical combiner of the present embodiment.

Embodiment one:

fig. 4 is a schematic structural diagram of a first application embodiment of the optical combiner provided in the present embodiment. The first polarization modulation module 40 in the optical combiner of the present embodiment is a combined grating composed of a first transmissive liquid crystal polarizer holographic grating 410 and a first transmissive volume holographic grating 420. The unpolarized light emitted by the opto-mechanical module 10 can be decomposed into 50% left-hand circularly polarized light and 50% right-hand circularly polarized light. As described in connection with fig. 2, after these unpolarized lights pass through the first transmissive liquid crystal polarizer holographic grating (PVG) 410, bragg diffraction occurs on polarized lights having the same spiral twist direction as the liquid crystal molecules, and the polarization rotation direction is reversed, and the diffraction angle can be designed by changing the grating parameters. In which polarized light having a direction opposite to the helical twist direction of the liquid crystal molecules is directly transmitted through the first transmissive liquid crystal polarization hologram (PVG) 410 to be incident on the first transmissive volume hologram 420. Therefore, after passing through the transmission type liquid crystal polarizer holographic grating (PVG), the incident unpolarized light is changed into circular polarized light with the same polarization rotation direction and has different diffraction angles, which are respectively、/>. Then, the light of the same circular polarization state passes through the first transmission type volume hologram 420, wherein the incident angle is +.>The circularly polarized light of (2) does not satisfy the bragg condition of the volume hologram grating and thus will directly pass through the first transmissive volume hologram grating 420. The other beam has an incident angle of->The circularly polarized light of (2) satisfies the Bragg condition of the volume holographic grating, thusBy designing parameters such as grating inclination angle, grating period, refractive index modulation degree and the like, the grating is adjusted to be equal to the incident angle +>The same angle exits. Therefore, after passing through the first transmissive volume hologram 420, the same polarized light having different exit angles will exit onto the coupling-in module 430 at the same angle. By combining the two gratings, the incident unpolarized light is converted into light with the same polarization state and the same emergent angle.

Further, as shown in fig. 4, if the coupling-in module uses a second transmissive liquid crystal polarizer holographic grating (PVG), the coupling-out module uses a second transmissive Volume Holographic Grating (VHG). The second transmissive liquid crystal polarizer holographic grating (PVG) will produce efficient bragg diffraction for light of the same polarization rotation, thereby fully utilizing the incident light energy. The outgoing light beams are incident on the first optical waveguide 440 at a certain angle through a second transmissive liquid crystal polarizer holographic grating (PVG) disposed on the first optical waveguide 440, and propagate in the first optical waveguide 440 under the condition of total internal reflection until being transmitted to the second transmissive liquid crystal polarizer holographic grating 450, and enter human eyes to form a virtual image display.

Further, a relay module is further disposed between the coupling-in module and the optical waveguide, and the relay module, the coupling-in module and the coupling-out module may be disposed on the same side surface of the optical waveguide; alternatively, the relay module, the in-coupling module and the out-coupling module are disposed on surfaces of different sides of the optical waveguide. For example: the second transmissive liquid crystal polarization volume hologram grating (PVG) 430 and the second transmissive volume hologram grating 450 in fig. 4 may also be reflection gratings. Accordingly, the second transmissive liquid crystal polarization volume hologram grating (PVG) 430 and the second transmissive volume hologram grating 450 may be disposed on the same surface of the optical waveguide or may be disposed on different surfaces.

Further, at the periphery of the optical combiner, a protective cover 20 is provided. An adhesive layer 30 is further provided between the protective cover 20 and the first optical waveguide 440.

Embodiment two:

in order to achieve a better polarized light adjusting effect, the polarization modulation module is provided with a 1/4 wave plate; the 1/4 wave plate is used for receiving circularly polarized light transmitted from the volume holographic grating and modulating the circularly polarized light into linearly polarized light.

In combination with the addition of a 1/4 wave plate 530 as shown in fig. 5, the incident circularly polarized light can be converted into homogeneous linear polarized light. Wherein the coupling-in module 540 and the coupling-out module 560 are surface relief gratings, respectively. The second polarization modulation module 50 can adjust the polarization direction of the linear polarized light irradiated to the coupling-in module 540 by synchronously selecting the directions of the third transmissive liquid crystal polarization volume holographic grating (PVG) 510, the third transmissive Volume Holographic Grating (VHG) 520, and the 1/4 wave plate 530, so that the polarization direction is consistent with the polarization direction with higher diffraction efficiency of the coupling-in module 540, thereby fully utilizing the incident light power. These outgoing beams are incident on the optical waveguide 550 at a certain angle through the coupling-in module 540 disposed on the optical waveguide 550, and propagate in the optical waveguide 550 under the condition of total internal reflection until being transmitted to the coupling-out module 560 to be coupled out, and enter the human eye to form a virtual image display.

In this embodiment, the coupling-in module may be configured as a transmissive liquid crystal polarizer holographic grating or a reflective liquid crystal polarizer holographic grating, and the coupling-out module may also be configured as a transmissive liquid crystal polarizer holographic grating or a reflective liquid crystal polarizer holographic grating.

Embodiment III:

the polarization modulation modules provided in the optical combiner of the embodiment are multiple groups, and the liquid crystal polarization holographic gratings and the volume holographic gratings in each group of polarization modulation modules are sequentially arranged at intervals; wherein, the polarization modulation modules of each group are respectively used for modulating the unpolarized light of different wave bands.

The polarization modulation modules and the optical waveguide modules are multiple groups, and the polarization modulation modules of each group are sequentially overlapped from top to bottom to form a combined polarization modulation module; each group of optical waveguides are sequentially overlapped and arranged from top to bottom to form a combined optical transmission module, and the combined polarization modulation module is positioned above each coupling-in module in the combined optical transmission module.

The combined polarization modulation module sequentially carries out polarization modulation on light of corresponding wave bands in the incident unpolarized light, then transmits the modulated polarized light of each wave band to each group of optical waveguide modules, couples the modulated polarized light into the coupling-in modules of the corresponding wave bands in each group of optical waveguide modules respectively, and couples the polarized light out of the coupling-out modules of the corresponding wave bands after transmitting the polarized light in the optical waveguides of the corresponding wave bands.

Referring to fig. 6, a plurality of sets of polarization modulation modules are disposed below the opto-mechanical module 10, where each set of polarization modulation modules includes a transmissive liquid crystal polarizer holographic grating (PVG) and a transmissive Volume Holographic Grating (VHG), for example, three sets of polarization modulation modules are included in the schematic diagram in fig. 6: a fourth polarization modulation module 60, a fifth polarization modulation module 70, and a sixth polarization modulation module 80, wherein the fourth polarization modulation module 60 comprises: a fourth transmissive liquid crystal polarizer holographic grating (PVG) 610 and a fourth transmissive Volume Holographic Grating (VHG) 620. The fifth polarization modulation module 70 includes: a fifth transmissive liquid crystal polarizer holographic grating (PVG) 630 and a fifth transmissive Volume Holographic Grating (VHG) 640. The sixth polarization modulation module 80 includes: a sixth transmissive liquid crystal polarizer holographic grating (PVG) 650 and a sixth transmissive Volume Holographic Grating (VHG) 660.

As shown in fig. 6, the fourth polarization modulation module 60, the fifth polarization modulation module 70, and the sixth polarization modulation module 80 are sequentially stacked from top to bottom to form a combined polarization modulation module, and the light beam modulated in the previous polarization modulation module is incident into the next polarization modulation module, and after being modulated again by the polarization modulation module located below, the light beam is transmitted into the next polarization modulation module located below, so as to modulate the unpolarized light emitted by the optical machine module by using multiple groups of polarization modulation modules. Because each polarization modulation module can be set to modulate the unpolarized light with a certain wavelength, a plurality of groups of light polarization modulation groups are used for modulating the unpolarized light with different wavebands respectively, the wavelength range of the light coupled into the optical waveguide is widened, the energy utilization rate of the light emitted by the optical module is increased, and the energy consumption is reduced.

In a specific implementation, increasing the number of transmissive liquid crystal polarizer holographic gratings (PVGs) and transmissive Volume Holographic Gratings (VHGs) may be a first, second, nth group, respectively. Each group of combination of the transmission type liquid crystal polarizer holographic grating (PVG) and the transmission type liquid crystal polarizer holographic grating (VHG) can be designed to carry out polarization modulation on light of a certain wave band, namely, the first, second, and N groups of grating combination respectively convert the light of the first, second, and N wave bands from the optical machine module into light beams with the same polarization rotation direction and the same emergent angle, so that the light emitted from the optical machine module is coupled into the optical waveguide in a wider wave band, the utilization rate of the light emitted from the optical machine module is improved, and the energy consumption is reduced.

Referring to fig. 6, in order to transmit unpolarized light of different wavebands into human eyes through an optical combiner, a combined optical transmission module is disposed below a combined polarization modulation module formed by polarization modulation modules, where the combined optical transmission module includes: a plurality of sets of optical waveguide modules. The coupling-in module and the coupling-out module are arranged on the surface of the optical waveguide according to the wave bands corresponding to the optical waveguides contained in the optical waveguide modules. In the implementation, the optical waveguide modules of each group in the combined optical transmission module are also overlapped in sequence, the coupling-in modules in each group of optical waveguide modules respectively couple the received polarized light of the corresponding wave band into the optical waveguide, the light which fails to couple into the optical waveguide is transmitted into the coupling-in module and the optical waveguide which are positioned below through the coupling-in module and the optical waveguide which are positioned above, after the light of the corresponding wave band is coupled into the coupling-in module and the optical waveguide, the light which is not coupled in is transmitted into the coupling-in module and the optical waveguide of the next group of optical waveguide module which are positioned below again through the coupling-in module and the optical waveguide, and then the light of a plurality of different wave bands is transmitted in the respective optical waveguides and is coupled out into human eyes through the corresponding coupling-out modules.

As shown in fig. 6, the fourth polarization modulation module 60, the fifth polarization modulation module 70, and the sixth polarization modulation module 80 are all disposed above the third optical waveguide 690, and then circularly polarized light is converted into linearly polarized light by the wide-spectrum 1/4 wave plate. Thus, the first, second, and third wavelength band light beams enter the respective optical waveguides through the third coupling-in module 680, the fourth coupling-in module 6120, and the fifth coupling-in module 6150 disposed on the third optical waveguide 690, the fourth optical waveguide 6130, and the fifth optical waveguide 6160, respectively, and are transmitted in the respective optical waveguides at the respective total internal reflection angles, until encountering the respective coupling-out modules (the third coupling-out module 6110, the fourth coupling-out module 6140, and the fifth coupling-out module 6170) to be coupled out to the human eye.

Embodiment four:

referring to fig. 7, the polarization modulation modules and the optical waveguides are all multiple groups, and a group of polarization modulation modules and a group of optical waveguide modules form a group of optical modulation modules; the light modulation modules of each group are sequentially arranged from top to bottom, and the polarization modulation modules are positioned above the coupling-in modules in the light waveguide modules.

The polarization modulation modules in each group of light modulation modules sequentially carry out polarization modulation on light with corresponding wave bands in the incident unpolarized light, the light is coupled into each group of light waveguides through the coupling-in modules with corresponding wave bands, and the light is transmitted in the light waveguides with corresponding wave bands and is coupled out from the coupling-out modules with corresponding wave bands after the transmission direction is changed by the relay modules with corresponding wave bands.

In one embodiment, the coupling-in module is a transmissive or reflective liquid crystal polarizer holographic grating, and the coupling-out module is a transmissive or reflective volume holographic grating.

As shown in fig. 7, the polarization modulation module, the coupling-in module, the optical waveguide, and the coupling-out module are combined into a set of optical modulation modules. Each polarization modulation module in each group of light modulation modules is respectively arranged above each group of corresponding light waveguide. The light of different wave bands modulated in each group of polarization modulation modules is coupled into the optical waveguide through the liquid crystal polarization holographic grating and then is respectively transmitted in the respective optical waveguide at the respective total internal reflection angle until encountering the respective volume holographic grating to be coupled out to human eyes.

Referring to fig. 7, when the light output from the optical machine module corresponds to the three sets of unpolarized light with different wavelengths, and the unpolarized light with the first set of wavelengths corresponds to the first optical machine module located at the top, the unpolarized light with the first set of wavelengths is incident on the seventh transmissive liquid crystal polarizer holographic grating (PVG) 710, passes through the eighth transmissive liquid crystal polarizer holographic grating (PVG) 720 located above the seventh optical waveguide 730, and then is coupled into the seventh optical waveguide 730, and is coupled out from the seventh transmissive liquid crystal polarizer holographic grating (VHG) 7150 of the same set after being transmitted through total reflection in the seventh optical waveguide 730. The other light beam in the second wavelength band emitted from the opto-mechanical module corresponds to the second optical modulation module, and the light beam in the second wavelength band passes through the seventh transmissive liquid crystal polarizer hologram (PVG) 710, the eighth transmissive liquid crystal polarizer hologram (PVG) 720, and the seventh optical waveguide 730, then enters the ninth transmissive liquid crystal polarizer hologram (PVG) 740, the eighth transmissive liquid crystal hologram (VHG) 750, is modulated by the ninth transmissive liquid crystal polarizer hologram (PVG) 740, the eighth transmissive liquid crystal hologram (VHG) 750, then enters the tenth transmissive liquid crystal polarizer hologram (PVG) 760, is coupled into the eighth optical waveguide 770 by the tenth transmissive liquid crystal polarizer hologram (PVG) 760, and is coupled out by the ninth transmissive liquid crystal polarizer hologram (VHG) 7140 after being totally reflected and propagated in the eighth optical waveguide 770. The other Shu Bochang emitted from the optical machine module corresponds to the light beam of the third optical modulation module, and sequentially passes through the seventh transmissive liquid crystal polarizer holographic grating (PVG) 710, the eighth transmissive liquid crystal polarizer holographic grating (PVG) 720, the seventh optical waveguide 730, the ninth transmissive liquid crystal polarizer holographic grating (PVG) 740, the eighth transmissive liquid crystal holographic grating (VHG) 750, the tenth transmissive liquid crystal polarizer holographic grating (PVG) 760, and the eighth optical waveguide 770 in the first optical modulation module, and then is incident on the eleventh transmissive liquid crystal polarizer holographic grating (PVG) 780. After being modulated by the eleventh transmissive liquid crystal polarization body hologram (PVG) 780 and the tenth transmissive liquid crystal polarization body hologram (VHG) 790, the light beam coupled out from the eleventh transmissive liquid crystal polarization body hologram (VHG) 7130 after being transmitted by total reflection in the ninth optical waveguide 7120 is coupled out from the ninth optical waveguide 7120 by the eleventh transmissive liquid crystal polarization body hologram (VHG) 7130, and is coupled out after passing through the eighth optical waveguide, the ninth transmissive liquid crystal polarization body hologram (VHG) 7140, the seventh optical waveguide 730, and the seventh transmissive liquid crystal polarization body hologram (VHG) 7150 in this order.

The optical combiner disclosed in this embodiment proposes to use a combination grating device of a plurality of sets of liquid crystal polarization volume holographic gratings and volume holographic gratings, efficiently couple multi-band incident light beams into an optical waveguide, and improve the brightness of a virtual image at a human eye on the premise of not increasing the power of an optical machine module, and further improve the color uniformity of the virtual image at the human eye.

The embodiment also discloses a near-eye display device on the basis of the optical combiner, wherein the near-eye display device comprises the optical combiner.

The embodiment discloses an optical combiner and near-to-eye display device, the optical combiner includes an optical waveguide, a coupling-in module, a coupling-out module and a polarization modulation module, the polarization modulation module is composed of different diffraction gratings, and the polarization modulation module is disposed between the optical machine module and the coupling-in module, and is used for transmitting polarized light which is sent out by the optical machine module and has different emergence angles and different polarization directions and is modulated into the same polarization direction to the coupling-in module in the same angle. The optical combiner provided by the embodiment converts incident unpolarized light into light with the same polarization rotation direction by using different types of diffraction gratings, thereby improving the utilization ratio of the optical waveguide to the incident light. The power consumption is reduced due to the increase in the light energy utilization rate, and the brightness of the virtual image incident into the eyes of the user is increased.

The number of combinations of the liquid crystal polarization body hologram grating and the arrangement position thereof relative to the optical waveguide in the polarization modulation module disclosed in the embodiment can be arbitrarily combined, and a single-band optical signal can be transmitted in the optical waveguide, and a plurality of band optical signals can be transmitted, so that the protection scope of the present patent is not limited. Therefore, by increasing the number of grating combinations and optical waveguides, a broadband, efficient near-to-eye display device can be realized.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or N embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims (10)

1. An optical combiner, comprising:

at least one group of polarization modulation modules consisting of diffraction gratings of different types; the polarization modulation module is arranged on an optical path of the unpolarized light output by the optical machine module and is used for modulating the unpolarized light with different emergence angles and any polarization directions emitted by the optical machine module into polarized light with the same polarization direction and the same emergence angle;

at least one set of optical waveguide modules comprising a coupling-in module, an optical waveguide and a coupling-out module; the coupling-in module is arranged on the surface of the optical waveguide and is used for receiving polarized light emitted from the polarization modulation module and coupling the received polarized light into the optical waveguide; the coupling-out module is arranged on the surface of the optical waveguide and is used for coupling out polarized light in the optical waveguide.

2. The light combiner of claim 1, wherein the polarization modulation module comprises at least one liquid crystal polarizer holographic grating and at least one volume holographic grating.

3. The optical combiner of claim 1, wherein the optical waveguide module further comprises a relay module; the optical waveguide is used for turning the propagation direction of the optical signal coupled into the optical waveguide from the coupling-in module, so as to realize two-dimensional pupil expansion;

the coupling-in module, the coupling-out module and/or the relay module are/is arranged on the surface of the same side of the optical waveguide; alternatively, the in-coupling module, the out-coupling module and/or the relay module are provided on surfaces of different sides of the optical waveguide.

4. The optical combiner of claim 2, wherein the polarization modulation module further comprises: a 1/4 wave plate;

the 1/4 wave plate is used for modulating circularly polarized light emitted from the volume holographic grating into linearly polarized light.

5. The optical combiner of any one of claims 1-4, wherein the in-coupling, out-coupling and/or relay modules are any one of a liquid crystal polarization volume holographic grating, a surface relief grating, a super surface.

6. The optical combiner of any one of claims 2-4, wherein the polarization modulation modules are in a plurality of groups, and the liquid crystal polarizer holographic gratings and the volume holographic gratings are arranged in sequence at intervals; wherein, the polarization modulation modules of each group are respectively used for modulating the unpolarized light of different wave bands.

7. The optical combiner of claim 1, wherein the polarization modulation modules and the optical waveguide modules are multiple groups, and each group of polarization modulation modules is sequentially overlapped from top to bottom to form a combined polarization modulation module; each group of optical waveguide modules are sequentially overlapped and arranged from top to bottom to form a combined optical transmission module, and the combined polarization modulation module is positioned above the coupling-in module in the combined optical transmission module;

the combined polarization modulation module sequentially carries out polarization modulation on light of corresponding wave bands in the incident unpolarized light, then transmits the modulated polarized light of each wave band to each group of optical waveguide modules, couples the modulated polarized light into the coupling-in modules of the corresponding wave bands in each group of optical waveguide modules respectively, and couples the polarized light out of the coupling-out modules of the corresponding wave bands after transmitting the polarized light in the optical waveguides of the corresponding wave bands.

8. The optical combiner of claim 1, wherein the polarization modulation modules and the optical waveguide modules are each a plurality of groups, and wherein a group of polarization modulation modules and a group of optical waveguide modules form a group of optical modulation modules; each group of light modulation modules are sequentially arranged from top to bottom, and the polarization modulation modules are positioned above each coupling-in module in the optical waveguide module;

the polarization modulation modules in each group of light modulation modules sequentially carry out polarization modulation on light with corresponding wave bands in the incident unpolarized light, the light is coupled into each group of light waveguides through the coupling-in modules with corresponding wave bands, and the light is transmitted in the light waveguides with corresponding wave bands and is coupled out from the coupling-out modules with corresponding wave bands after the transmission direction is changed by the relay modules with corresponding wave bands.

9. The optical combiner according to claim 7 or 8, wherein the in-coupling, out-coupling and/or relay modules are any one of a liquid crystal polarizer holographic grating, a volume holographic grating, a surface relief grating, a super surface.

10. A near-eye display device comprising an optical combiner as claimed in any one of claims 1-9.