CN113341569B - Polarization multiplexing diffraction waveguide large-view-field angle imaging system and method - Google Patents
Polarization multiplexing diffraction waveguide large-view-field angle imaging system and method Download PDFInfo
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- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
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- G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
- G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
- G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
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- G02B6/0033—Means for improving the coupling-out of light from the light guide
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- G02B2027/0123—Head-up displays characterised by optical features comprising devices increasing the field of view
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- G02B2027/0174—Head mounted characterised by optical features holographic
Abstract
The invention discloses a polarization multiplexing diffraction waveguide large-view-field angle imaging system and a method, wherein the imaging system sequentially comprises an image source, a polarization component, a collimation system and a waveguide structure, the imaging method utilizes the polarization selectivity of a polarizer holographic liquid crystal grating to realize large-scale expansion of the view field angle under the polarization multiplexing method, utilizes a laminated composite structure of the polarizer holographic liquid crystal grating to set the space period and the grating vector direction of grating components, is matched with the polarization setting of the image source to couple and guide view field beams in different polarization states into a waveguide medium in different directions, and finally is coupled and guided out of the waveguide to realize the superposition of the view field to realize the large-scale expansion of the view field range.
Description
Technical Field
The invention relates to a polarization multiplexing diffraction waveguide large-view-field angle imaging system and a method, which are used for realizing image transmission capability of a large view field in holographic waveguide AR display. The polarization selectivity of the polarizer holographic liquid crystal grating can be utilized to realize the path transmission of different polarization state field ranges from the collimating image source in the same waveguide medium and finally couple and guide out the waveguide to complete the field splicing, thereby realizing the large field expansion.
Background
Based on a report of 58 pages released in 2016, 1 month, Augmented Reality (AR) will become a subversive technology that affects many industries, from gaming to military. One of the key hardware of the AR display technology is an optical combiner, which superimposes the external real environment with the virtual image generated by the micro image source system to form a virtual-real combined function. In order to solve the problems of the conventional near-eye optics that the optical component in front of the eye is too thick and the size of the exit pupil is limited in a large field range, the use of the diffractive waveguide imaging technology as an optical combiner has received extensive attention in academia and industry. Compared with near-to-eye display schemes based on geometrical optics principles (such as prism schemes, free-form surface schemes and the like), the optical waveguide structure is thinner and thinner (generally 0.5mm-2mm), and is closer to the definition of 'AR glasses'.
The small field of view (FOV) is a bottleneck problem that exists in current diffractive light waveguide imaging and limits its further development. The small FOV means that the virtual image observed by human eyes is small, and the color expression and the imaging uniformity under a large viewing angle are also affected. The main problems of difficult expansion of the diffractive waveguide imaging FOV can be attributed to the narrow response bandwidth of the waveguide coupling grating and the limited propagation angle of the light beam under the limitation of the refractive index of the waveguide medium. From the aspect of improving the response bandwidth of the waveguide coupling grating, the polarizer holographic liquid crystal grating (PVG) prepared by using the liquid crystal material has a larger birefringence difference, so that a larger response bandwidth can be provided compared with the traditional diffraction grating, and a larger field angle is further realized.
Although the optical waveguide made of PVG itself can improve the FOV to a certain extent, the effect is limited by the influence of the refractive index of the waveguide medium, the refractive index of the grating material and the shape of the waveguide, and is still limited, and it is difficult to meet the requirement of people on the augmented reality display effect.
Disclosure of Invention
The technical problem is as follows: aiming at the defects to be solved in the prior art, the invention provides a polarization multiplexing diffraction waveguide large-view-field-angle imaging system and method, which are used for improving the field angle of a diffraction waveguide and solving the key problem of FOV limitation.
The technical scheme is as follows: the invention discloses a polarization multiplexing diffraction waveguide large-view-field angle imaging system which sequentially comprises an image source, a polarization component, a collimation system and a waveguide structure,
the image source is an image source required by the system and is an OLED (organic light emitting diode), an LCOS (liquid Crystal on silicon) or a MicroLED (micro light emitting diode);
the polarization components are respectively a left circular polarization component for generating left circular polarized light and a right circular polarization component for generating right circular polarized light;
the collimation system utilizes a lens to enable light beams to be parallel, and adopts a free-form surface-based collimation system and an off-axis collimation system;
the waveguide structure is composed of an in-coupling component, a left-handed circular polarized light steering grating, a right-handed circular polarized light steering grating, an out-coupling component and a waveguide medium.
The imaging method of the polarization multiplexing diffraction waveguide large-view-field-angle imaging system utilizes a laminated composite structure of a polarization body holographic liquid crystal grating (PVG), sets the space period of grating components and the grating vector direction, is matched with image source polarization setting, couples and guides the view field light beams in different polarization states into a waveguide medium in different directions, and finally couples and guides out the waveguide to realize the superposition of the view field and realize the large-scale expansion of the view field range.
The linear polarization image emitted by the image source is converted into a left-handed circular polarization image and a right-handed circular polarization image after passing through a left-handed circular polarization component and a right-handed circular polarization component, and enters the waveguide structure through the collimation system; the in-coupling component in the waveguide structure consists of a left-handed circular polarized light coupling grating and a right-handed circular polarized light coupling grating, the rotation directions of liquid crystal molecules of the left-handed circular polarized light coupling grating and the right-handed circular polarized light coupling grating are opposite and have the same periodicity, and incident light output by the collimation system is diffracted to +1 level and-1 level and is used for separating incident light beams with different polarizations; the middle steering area consists of a left-handed circular polarized light steering grating and a right-handed circular polarized light steering grating and is used for completing the light beam expansion in the one-dimensional direction and steering the light beam; the out-coupling component consists of a left-handed circular polarized light coupling grating and a right-handed circular polarized light coupling grating which have opposite rotation directions of liquid crystal molecules and the same periodicity, and is used for guiding the light beams in the two directions out of the waveguide and splicing the view fields again; the gratings all use a polarizer holographic liquid crystal grating PVG, wherein the left-handed circular polarized light coupling grating can diffract left-handed circular polarized light, the right-handed circular polarized light directly penetrates through the left-handed circular polarized light coupling grating, the right-handed circular polarized light coupling grating can diffract right-handed circular polarized light, and the left-handed circular polarized light directly penetrates through the right-handed circular polarized light coupling grating.
The exposure of the polarizer holographic liquid crystal grating PVG adopts a polarization holographic exposure device, two beams of polarized light are subjected to interference exposure on a waveguide medium coated with a photo-alignment material film, and a photo-alignment layer is further formed; a liquid crystal mixture solution containing a liquid crystal polymer and a chiral material is coated on the formed alignment layer.
The liquid crystal mixture solution is coated by using a coating method, and area spraying and film pasting are carried out.
The left-handed circular polarization component and the right-handed circular polarization component are two wave plates, a part of the two wave plates is overlapped, or the overlapped part is replaced by a half wave plate, and the scheme prevents the division of the view field generated during the view field splicing.
The image source adopts a polarization type micro display, including LCOS or a micro display based on liquid crystal, so as to improve the utilization rate of the brightness of the image source.
The waveguide medium selects glass with high refractive index as a substrate, and in order to enable light beams to propagate along the waveguide, the minimum propagation angle alpha in the waveguideminThe critical angle of the waveguide medium is larger than or equal to the critical angle, and is calculated by the formula (1):
αmin＝arcsin(1/nglass) (1)
n in the formula (1)glassA refractive index value representative of the waveguide material used; the waveguide material is selected from materials with high refractive index to form a larger angle propagation range in the waveguide so as to form a larger angle of view from the formula (1); while the maximum propagation angle alphamaxMay be in (α)min90 deg., the larger the angle of view that is finally formed.
The left-handed light beams and the right-handed light beams output by the left-handed circular polarized light coupling grating and the right-handed circular polarized light coupling grating are transmitted in the same angle range in the waveguide, so that the gratings at the in-coupling area and the out-coupling area need to be ensured to be same in periodicity; the specific grating period needs to be calculated according to a Bragg formula, which is as follows (2):
therefore, the required grating period can be found by the following equation:
neffrepresents the equivalent refractive index of the birefringent material used for the grating; lambdaxRepresents the horizontal period length of the grating in the x direction; xi represents the included angle between the optical axis of the liquid crystal molecules and the z axis; lambda [ alpha ]BRepresentsBragg wavelength in vacuum.
Has the advantages that: the invention uses the polarizer holographic grating as the in-out coupling element and the middle steering grating of the waveguide display, the grating has unique polarization characteristic while having wider response bandwidth, and the large field effect of the polarization multiplexing structure under the two-dimensional pupil expanding structure is realized by using the characteristic, thereby solving the problem that the near-eye display FOV is limited.
Drawings
FIG. 1 is a diagram of a PVG structure;
FIG. 2 is a diagram illustrating PVG polarization response;
FIG. 3 is a diagram of the bandwidth of the left-handed and right-handed circular polarization angles of PVG at the incoupling site;
FIG. 4 is a schematic plan view of a waveguide structure of a polarization multiplexing diffractive waveguide according to the present invention;
FIG. 5 is a schematic diagram of a polarization multiplexing diffractive waveguide system according to the present invention;
FIG. 6 is a diagram showing the size of the grating in each region;
FIG. 7 is a schematic diagram of an improved polarization multiplexed diffractive waveguide system;
FIG. 8 is a schematic diagram of a color image polarization multiplexed diffractive waveguide system.
The figure includes: the device comprises an image source 1, a left-handed circular polarization component 2, a right-handed circular polarization component 3, a collimation system 4, an in-coupling component 5, a left-handed circular polarization steering grating 6, a right-handed circular polarization steering grating 7, an out-coupling component 8, a waveguide medium 9, a left-handed circular polarization optical coupling grating 10, a right-handed circular polarization optical coupling grating 11, a left-handed light beam 12, a right-handed optical beam 13, a half-wave plate 14, a red waveguide layer 15, a green waveguide layer 16 and a blue waveguide layer 17.
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
Figure 1 shows the structure of PVG. As can be seen from fig. 1, the polarizer holographic grating PVG has a two-dimensional periodic structure.
Wherein, in an x-z plane (horizontal plane), an included angle alpha between the optical axis of the liquid crystal molecules and the z axis can be periodically changed along the x direction, namely the horizontal direction,the period length of which is designated Λx。
In the y-z plane, the liquid crystal material (or more broadly, birefringent material) exhibits a periodic helical structure in the y-direction, i.e. the vertical direction, with a period denoted Λy。
Such a two-dimensional periodic structure can produce a series of tilted refractive index planes with periodicity, whose tilt angle ξ can be calculated by equation (8):
ξ＝arctan(Λy/Λx) (8)
if the birefringent material layer is thick enough, Bragg diffraction can be established. Bragg diffraction is represented by formula (6):
n in the formula (6)effRepresents the equivalent refractive index of the birefringent medium; lambda [ alpha ]BRepresenting the bragg wavelength in vacuum.
Calculated from equation (9):
calculating the incident angle theta under the non-Bragg conditioniAnd obtaining the angle relation between the diffracted light beams and the incident light beams through a plane grating formula (dispersion equation) at the corresponding diffraction angle, namely:
in the formula (10), θdiffRepresenting the diffraction angle (angle of propagation of the beam in the waveguide), nglassRepresenting the refractive index value of the glass waveguide, λ representing the wavelength of the light beam, θincRepresenting the angle of incidence in air, m representing the diffraction order (m 1 for a bulk grating), axRepresenting the horizontal period length of the grating in the x-direction.
As shown in fig. 2, a PVG polarization response is demonstrated. The liquid crystal molecules of the left-handed circularly polarized light coupling grating 10 and the right-handed circularly polarized light coupling grating 11 rotate in opposite directions in the two layers but have the same periodicity, so that the left-handed light beam 12 and the right-handed light beam 13 can be diffracted, respectively.
The central incident angles of the levorotatory circular polarized light coupling grating 10 and the dextrorotatory circular polarized light coupling grating 11 are respectively related to the levorotatory image and the dextrorotatory image FOV entering the waveguide medium, and the maximum incident angle of the levorotatory image entering the waveguide medium is assumed to be
Minimum incident angle of
The central incident angle of the levorotatory circular polarized light coupling grating 10 should be
Is recorded as betalThe corresponding Bragg formula is
2neffΛx sin(ξ)cos(ξ+βl)＝λ
Similarly, assume that the maximum angle of incidence of a right-hand image into the waveguide medium is
Minimum incident angle of
The central incident angle of the right-handed circularly polarized light coupling grating 11 should be
The optical coupling grating 11 should be beta, denoted as beta, D-R circularly polarizedrThe corresponding Bragg formula is
2neffΛx sin(ξ)cos(ξ+βr)＝λ
The present invention gives an angular bandwidth diagram of exemplary levorotatory and dextrorotatory circularly polarized optical coupling gratings 10, 11 for ease of understanding, as shown in figure 3.
Fig. 4 is a schematic diagram of the waveguide structure of the polarization multiplexing diffraction waveguide according to the present invention. The structure is based on a two-dimensional pupil expanding structure of PVG, an in-coupling component 5 is structurally shown in figure 2 and consists of two layers of PVG which are opposite in liquid crystal molecule rotation direction and same in periodicity, namely a left-handed circularly polarized light out-coupling grating 10 and a right-handed circularly polarized light out-coupling grating 11, incident light is diffracted to +1 level and-1 level for separating incident light beams with different polarizations, wherein left-handed circularly polarized light is diffracted to-1 level, the left-handed circularly polarized light enters a left-handed circularly polarized light steering grating 6 on the left side, the right-handed circularly polarized light is diffracted to-1 level, and the circularly polarized light enters a right-handed circularly polarized light steering grating 7 on the right side. The left and right circularly polarized light steering gratings complete the light beam expansion in one dimension and simultaneously steer the light beam, and odd-order coupling occurs at the gratings. Finally, the waveguide 9 is led out from the out-coupling component 8 to complete the field splicing, and the out-coupling component 8 is also composed of a left-handed circularly polarized out-coupling grating 10 and a right-handed circularly polarized out-coupling grating 11 as shown in fig. 2.
It is to be noted that the incoupling component 5 is circular in the illustration and the turning grating is trapezoidal, and that in practice we can use gratings of any shape. The size of the incoupling component 5 cannot be too large, so that the waveguide structure is prevented from being too large in overall size and is not suitable for near-eye display.
As embodiment 1 of the present invention, fig. 5 is a schematic diagram of a system structure of a polarization-multiplexing diffraction waveguide according to the present invention. An image source 1 emits an image source, and a left-handed polarization image and a right-handed polarization image are formed after the image source passes through a left-handed circular polarization component 2, a right-handed circular polarization component 3 and a collimation system 4. The left-handed polarization image and the right-handed polarization image are projected to the in-coupling component 5, the left-handed polarization image is diffracted by a left-handed circular polarization grating 10 of the in-coupling component 5, the right-handed polarization image is diffracted by a right-handed circular polarization grating 11, the two images enter the waveguide medium 9 after being subjected to Bragg diffraction, the two images are transmitted in the waveguide medium 9 through total internal reflection in the same transmission angle range, the left-handed polarization image is diffracted to realize steering after passing through the left-handed circular polarization steering grating 6, and is diffracted to form a left view field after passing through the out-coupling component 8, the right-handed polarization image is diffracted after passing through the right-handed circular polarization steering grating 7, and is diffracted to form a right view field after passing through the out-coupling component 8, and finally the left view field and the right view field are spliced.
The in-coupling part 5 is located in the center of the two steering gratings, the two steering gratings should be kept horizontally symmetrical, and the out-coupling part 8 is vertically centered relative to the in-coupling part 5 and the two steering gratings, so that the symmetry of the structure and the field of view is kept.
In order to ensure complete transfer of the image, the size of the gratings in the respective regions is required, and the dimensions of the steering grating and the outcoupling grating are closely related to the FOV of the image source. As shown in fig. 6, α is half of the FOV of the image source, and assuming that the radius of the in-coupling grating 5 is r, the distance between a point a on the left-handed circularly polarized light steering grating 6 and the right-handed circularly polarized light steering grating 7 and a point C on the arc right above the center of the in-coupling grating 5 is d1Then the length of the steering grating AB is at least
2d1×sin α+2r，
The distance between a point D on the left-hand circular polarized light steering grating 6 and a point D on the right-hand circular polarized light steering grating 7 and a point C on an arc right above the circle center of the in-coupling grating 5 is D2Then the length of the steering grating DE is at least
2d2×sin α+2r。
Similarly, assume AF is a distance d3The length of the FG on the coupling grating 8 can be calculated to be at least
2d3×sin α+(d2-d1)cos α，
Suppose the length of AH is d4The HI can be calculated to be at least as long as
2d4×sin α+(d2-d1)cos α
This calculation method is based on the shape calculation shown in fig. 6, and other shape calculation methods are similar.
In the second embodiment, as a preferred scheme of the present invention, to prevent the image splitting in the final viewing field, we overlap the middle parts of the right-handed circular polarization component 2 and the left-handed circular polarization component 3, the overlapped part can also be replaced by a half-wave plate 14, and the circular polarization components on both sides can adopt quarter-wave plates, that is, the quarter-wave plates on both sides and the half-wave plate in the middle. After an image emitted by the image source 1 passes through the wave plate, a part of light in the middle is linearly polarized light, the part of light is respectively diffracted to a left view field and a right view field through the collimating system 4 and the coupling component 5, and finally image restoration is completed at the coupling-out position, as shown in fig. 7, the realization principle of transmission in the waveguide is the same as that of the first embodiment.
Embodiment three, as shown in fig. 8, a polarization multiplexing diffraction waveguide structure for realizing color transmission is provided. The implementation principle is basically similar to that of the second embodiment. Different from the above, the PVG corresponding to the red, green and blue bands needs to be set. The in-coupling region, the steering grating and the out-coupling region in the blue, green and red waveguide structures are all blue, green and red PVGs. The waveguide sheets with different colors are separated by air layers.
According to Bragg formula (2), when the wavelength value is λBIs 457nm (blue),
for the refractive index plane tilt angle in the blue waveguide layer, ΛxA horizontal period length value for the blue waveguide layer; when wavelength value lambdaBIs 532nm (green),
for refractive index plane tilt angles in green waveguide layers, ΛxIs the green waveguide layer horizontal period length value.
The image light beam of the red waveband directly penetrates through the blue waveguide layer 17 and the green waveguide layer 16, is diffracted to enter the waveguide when passing through the red in-coupling waveguide layer 15, and then is subjected to image transmission in the second embodiment; similarly, the image light beam in the green wavelength band directly passes through the blue waveguide layer 17 and the red waveguide layer 15, and is diffracted to enter the waveguide when passing through the green waveguide layer 16, and then the image transmission in the second embodiment is performed; the image light beam in the blue wavelength band passes through the green waveguide layer 16 and the red waveguide layer 15, passes through the blue waveguide layer 17, is diffracted, enters the waveguide, and then is transmitted as an image in embodiment two.
Claims (7)
1. A polarization multiplexing diffraction waveguide large-view-field angle imaging system is characterized by sequentially comprising an image source (1), a polarization component, a collimation system and a waveguide structure,
the image source (1) is an image source required by the system and is an OLED, LCOS or MicroLED;
the polarization components are respectively a left circular polarization component (2) for generating left circular polarized light and a right circular polarization component (3) for generating right circular polarized light;
the collimation system (4) enables the light beams to be parallel by using a lens, and adopts a free-form surface-based collimation system and an off-axis collimation system;
the waveguide structure consists of an in-coupling component (5), a left-handed circular polarized light steering grating (6), a right-handed circular polarized light steering grating (7), an out-coupling component (8) and a waveguide medium (9);
the left-handed circular polarization component (2) and the right-handed circular polarization component (3) are two wave plates, and a part of the two wave plates is overlapped or the overlapped part is replaced by a half wave plate, so that the view field division generated during view field splicing is prevented.
2. An imaging method of the polarization multiplexing diffraction waveguide large-view-field-angle imaging system as claimed in claim 1, wherein a laminated composite structure of a polarizer holographic liquid crystal grating PVG is used to set a spatial period of a grating component and a grating vector direction, and an image source polarization setting is matched to couple and guide field beams of different polarization states into a waveguide medium in different directions, and finally couple and guide out the waveguide to realize the superposition of a view field and realize the large-scale expansion of a view field range;
the linear polarization image emitted by the image source (1) is converted into a left-handed circular polarization image and a right-handed circular polarization image after passing through a left-handed circular polarization component (2) and a right-handed circular polarization component (3), and enters the waveguide structure through the collimation system; the in-coupling component (5) in the waveguide structure consists of a left-handed circular polarized light coupling grating (10) and a right-handed circular polarized light coupling grating (11), the rotation directions of liquid crystal molecules of the left-handed circular polarized light coupling grating (10) and the right-handed circular polarized light coupling grating (11) are opposite and have the same periodicity, and incident light output by the collimation system (4) is diffracted to +1 level and-1 level for separating incident light beams with different polarizations; the middle steering area consists of a left-handed circular polarized light steering grating (6) and a right-handed circular polarized light steering grating (7) and is used for completing the light beam expansion in the one-dimensional direction and steering the light beam; the outcoupling component (8) consists of a left-handed circular polarized light coupling grating (10) and a right-handed circular polarized light coupling grating (11) which have opposite rotation directions of liquid crystal molecules and the same periodicity, and is used for guiding the light beams in the two directions out of the waveguide and splicing the view fields again; each grating uses a polarizer holographic liquid crystal grating PVG, wherein the left-handed circular polarized light coupling grating (10) can diffract left-handed circular polarized light, the right-handed circular polarized light directly penetrates through the grating, the right-handed circular polarized light coupling grating (11) can diffract right-handed circular polarized light, and the left-handed circular polarized light directly penetrates through the grating;
the left-handed circular polarization component (2) and the right-handed circular polarization component (3) are two wave plates, a part of the two wave plates is overlapped, or the overlapped part is replaced by a half wave plate, and the scheme prevents the division of the view field generated during the view field splicing.
3. The imaging method of the polarization multiplexing diffraction waveguide large-view-field-angle imaging system according to claim 2, wherein a polarization holographic exposure device is adopted for exposure of the polarizer holographic liquid crystal grating PVG, two beams of polarized light are subjected to interference exposure on a waveguide medium (9) coated with a photo-orientation material film, and a photo-orientation layer is further formed; a liquid crystal mixture solution containing a liquid crystal polymer and a chiral material is coated on the formed alignment layer.
4. The imaging method of the polarization multiplexing diffraction waveguide large-field-angle imaging system according to claim 3, wherein the liquid crystal mixture solution is coated by area spraying and pasting.
5. The imaging method of the polarization multiplexing diffractive waveguide large field angle imaging system according to claim 2, wherein the method comprisesThe waveguide medium (9) is formed by selecting glass with high refractive index as a substrate, and the minimum propagation angle alpha in the waveguide is used for enabling light beams to propagate along the waveguideminThe critical angle of the waveguide medium is larger than or equal to the critical angle, and is calculated by the formula (1):
αmin＝arcsin(1/nglass) (1)
n in the formula (1)glassA refractive index value representative of the waveguide material used; the waveguide material is selected from materials with high refractive index to form a larger angle propagation range in the waveguide so as to form a larger angle of view from the formula (1); while the maximum propagation angle alphamaxMay be in (α)min90 deg., the larger the angle of view that is finally formed.
6. The imaging method of the polarization multiplexing diffraction waveguide wide-field-angle imaging system according to claim 2, wherein the left-handed light beam (12) and the right-handed light beam (13) output by the left-handed circularly polarized light coupling grating (10) and the right-handed circularly polarized light coupling grating (11) propagate in the waveguide in the same angle range, so that it is required to ensure that the gratings at the in-coupling region and the out-coupling region keep the same periodicity; the specific grating period needs to be calculated according to a Bragg formula, which is as follows (2):
therefore, the required grating period can be found by the following equation:
neffrepresents the equivalent refractive index of the birefringent material used for the grating; lambdaxRepresents the horizontal period length of the grating in the x direction; xi represents the included angle between the optical axis of the liquid crystal molecules and the z axis; lambda [ alpha ]BRepresenting the bragg wavelength in vacuum.
7. The imaging method of the polarization multiplexing diffractive waveguide wide-field-angle imaging system according to claim 2, wherein the in-coupling component, the middle turning region, and the out-coupling component of the red waveguide layer 15 are all red PVG, the in-coupling component, the middle turning region, and the out-coupling component of the green waveguide layer 16 are all green PVG, and the in-coupling component, the middle turning region, and the out-coupling component of the blue waveguide layer 17 are all blue PVG.
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| CN114089531B (en) * | 2021-11-16 | 2022-08-09 | 浙江大学 | Binocular waveguide display method based on reflective polarization multiplexing liquid crystal lens |
| CN114236819B (en) * | 2021-12-29 | 2022-09-27 | 东南大学 | Waveguide display two-dimensional pupil expanding method based on polarizer holographic grating |
| US20230213760A1 (en) * | 2021-12-30 | 2023-07-06 | Goertek Inc. | Optical waveguide system and electronic device |
| CN114488523A (en) * | 2022-01-28 | 2022-05-13 | 东南大学 | Optical display system and method for expanding holographic display eye box and field angle |
| WO2023215339A1 (en) * | 2022-05-06 | 2023-11-09 | Google Llc | Waveguide input coupler multiplexing to reduce exit pupil expansion ray footprint |
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| CN114879299B (en) * | 2022-07-11 | 2022-10-04 | 南京平行视界技术有限公司 | Color waveguide display device for improving imaging uniformity |
| CN115016128B (en) * | 2022-08-08 | 2022-12-02 | 南京平行视界技术有限公司 | Holographic waveguide HUD device based on polarizer |
| CN115097637B (en) * | 2022-08-26 | 2022-12-09 | 杭州光粒科技有限公司 | Head-up display |
| TWI814557B (en) * | 2022-08-30 | 2023-09-01 | 友達光電股份有限公司 | Optical module and augmented reality near-eye display including the same |
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