CN217718285U

CN217718285U - Apparatus for manufacturing holographic optical element and near-to-eye display device

Info

Publication number: CN217718285U
Application number: CN202221984185.0U
Authority: CN
Inventors: 郝希应; 张倩; 王雁茹
Original assignee: Sunny Optical Zhejiang Research Institute Co Ltd
Current assignee: Sunny Optical Zhejiang Research Institute Co Ltd
Priority date: 2022-07-29
Filing date: 2022-07-29
Publication date: 2022-11-01
Anticipated expiration: 2032-07-29

Abstract

The utility model relates to a device and near-to-eye display device for making holographic optical element, it can avoid the image to reveal, protects user's use privacy when improving actual transmittance. The near-eye display device includes: an image projector for projecting image light; a light splitting element disposed on a projection side of the image projector for reflecting a portion of the light and transmitting another portion of the light; a holographic optical element disposed at a reflection side of the light splitting element, the light splitting element for reflecting the image light from the image projector to be incident to the holographic optical element with a predetermined spatial angle distribution, the holographic optical element for redirecting the image light incident with the predetermined spatial angle distribution to propagate to the light splitting element and transmitting the light incident with other spatial angle distributions.

Description

Apparatus for manufacturing holographic optical element and near-to-eye display device

Technical Field

The present invention relates to the field of micro-display technology, and more particularly, to a device for manufacturing a Holographic Optical Element (HOE) and a near-to-eye display apparatus.

Background

In recent years, the advent of micro display chip technology has made possible miniaturization and high-resolution projection display. With the continuous development of projection display technology and market demand, wearable micro-lens systems are receiving more and more attention, especially in the fields of developing fire-heat Augmented Reality (AR), near-eye display (NED) and the like nowadays.

Currently, there are many AR optical system solutions on the market, but the near-eye display device really capable of facing the consumer still has many disadvantages, such as low brightness, small angle of view, large size, high cost or heavy device. Although a reflective Birdbath optical architecture (BB optical architecture for short) based on a self-luminous display chip as an image display source is very attractive because it has certain advantages in controlling cost, reducing volume and reducing difficulty, the curved mirror in the near-eye display scheme based on such an architecture has the following two drawbacks: 1) The actual transmittance is not high, and generally only the transmittance is about 20 percent; 2) There is image light escaping forward, causing the privacy of the user to be revealed.

As shown in fig. 1, the conventional catadioptric Birdbath optical system 1P is generally composed of an image display 10P, an imaging lens 20P, a concave mirror 30P (coated spectral ratio R =60%, T = 40%), and a flat half mirror 40P (coated spectral ratio R =50%, T = 50%). Thus, the image light emitted by the image display 10P passes through the imaging lens 20P, is reflected by the flat half mirror 40P, is reflected by the concave mirror 30P, and then reaches the human eyes through the flat half mirror 40P; meanwhile, external ambient light sequentially penetrates through the concave reflector 30P and the plane half-reflecting mirror 40P to reach human eyes, so that the human eyes can see virtual images and a real environment at the same time to obtain AR experience.

However, the catadioptric Birdbath optical system 1P has only about 20% of actual transmittance, and is extremely low, which seriously affects the practicability of the AR device; moreover, while the image light reflected by the plane half mirror 40P is reflected by the concave mirror 30P, a part of the image light can pass through the concave mirror 30P and be viewed by others, which causes the problem of image leakage and affects the use privacy of users.

SUMMERY OF THE UTILITY MODEL

An advantage of the present invention is to provide an apparatus for manufacturing holographic optical element and near-to-eye display device, which can avoid image leakage and protect user's use privacy while improving actual transmittance.

Another advantage of the present invention is to provide a device and near-to-eye display device for manufacturing holographic optical element, wherein, in an embodiment of the present invention, the near-to-eye display device only adopts holographic optical element to replace the concave mirror in the existing BB optical structure, and can realize the effect of improving the actual transmittance and protecting the privacy, and greatly improve the practicality of the AR device, and is convenient for popularization and promotion.

Another advantage of the present invention is to provide an apparatus for manufacturing a holographic optical element and a near-to-eye display device, wherein, in an embodiment of the present invention, the holographic optical element can make the diffraction efficiency of the image reproduction light up to 80% (the reflectivity of the existing concave mirror is generally 50%), which helps to greatly improve the optical system efficiency.

Another advantage of the present invention is to provide an apparatus for manufacturing a holographic optical element and a near-to-eye display device, wherein, in an embodiment of the present invention, the holographic optical element can reflect image reproduction light in its entirety, avoiding image light leakage, and effectively protecting user's use privacy.

Another advantage of the present invention is to provide an apparatus for manufacturing a holographic optical element and a near-to-eye display device, in which in order to achieve the above objects, it is not necessary to adopt expensive materials or complicated structures in the present invention. Accordingly, the present invention successfully and effectively provides a solution that not only provides a simple apparatus for manufacturing a holographic optical element and a near-eye display device, but also increases the practicality and reliability of the apparatus for manufacturing a holographic optical element and the near-eye display device.

In order to realize the utility model discloses an above-mentioned at least advantage or other advantages and purpose, the utility model provides a near-to-eye display device, include:

an image projector for projecting image light;

a light splitting element disposed on a projection side of the image projector for reflecting a portion of the light and transmitting another portion of the light;

a hologram optical element disposed at a reflection side of the light splitting element, the light splitting element configured to reflect the image light from the image projector to be incident to the hologram optical element with a preset spatial angle distribution, the hologram optical element configured to redirect the image light incident with the preset spatial angle distribution to propagate to the light splitting element and transmit light incident with other spatial angle distributions.

According to one embodiment of the present application, the surface type of the holographic optical element is a plane or a curved surface.

According to one embodiment of the application, the image projector comprises an image source for emitting image light and an imaging lens for modulating light, the imaging lens being arranged in an optical path between the image source and the light splitting element for modulating image light from the image source for propagation to the light splitting element.

According to one embodiment of the present application, the light splitting element is a flat plate light splitting member, the flat plate light splitting member and the holographic optical element are arranged along an observation axis of the near-eye display device, and an included angle between the flat plate light splitting member and the observation axis is between 50 ° and 70 °.

According to one embodiment of the present application, the flat light splitter is a half-reflecting and half-transmitting mirror, and is configured to reflect 50% of light and transmit 50% of light.

According to an embodiment of the present application, the light splitting element is a polarization light splitting member for reflecting the first polarized light and transmitting the second polarized light, and the near-eye display device further includes a 1/4 wave plate disposed between the polarization light splitting member and the holographic optical element for converting the twice-passed first polarized light into the second polarized light.

According to one embodiment of the application, the holographic optical element comprises a light-transmitting substrate and an HOE coating arranged on the light-transmitting substrate, wherein the HOE coating faces the light splitting element, and the HOE coating records information of interference between reference light distributed at a preset spatial angle and object light distributed in parallel at different angles.

According to another aspect of the present application, there is further provided an apparatus for manufacturing a holographic optical element, comprising:

the light source projector is used for projecting parallel light at different angles;

the parallel light beam splitter is arranged on the projection side of the light source projector and is used for splitting one path of parallel light from the light source projector into reference light propagating along a reference light optical path and object light propagating along an object light optical path;

the reference light system is arranged on a reference light optical path of the parallel light beam splitter and used for modulating the reference light from the parallel light beam splitter to form reference light with preset spatial angle distribution to be incident to the HOE substrate; and

and the object light system is arranged on an object light optical path of the parallel beam splitter and is used for modulating the object light from the parallel beam splitter to form object light which is distributed in parallel at different angles and is incident to the HOE substrate, so that the reference light distributed at a preset spatial angle and the object light distributed in parallel at different angles are subjected to interference recording at the HOE substrate, and the HOE substrate forms a holographic optical element.

According to one embodiment of the application, the object optical system comprises an object light relay lens group, an object light imaging lens, an object light splitter and a concave reflector which are sequentially arranged along an object light optical path of the parallel light splitter; the object light relay lens group is used for modulating the object light from the parallel beam splitter to form an object light intermediate real image in front of the object light imaging lens; the object light imaging lens is used for modulating object light forming the intermediate real image of the object light to form object light distributed in a preset space angle; the object light splitter is used for reflecting the object light from the object light imaging lens to be incident to the concave reflecting mirror; the concave reflector is used for reflecting object light distributed at a preset space angle to form object light distributed in parallel at different angles; the object beam splitter is further configured to transmit object beams distributed in parallel at different angles to be directed away from the HOE coating layer incident on the HOE substrate.

According to one embodiment of the present application, the object beam splitter is a PBS beam splitter prism for reflecting light of a first polarization and transmitting light of a second polarization; and the object optical system further comprises a phase delay member disposed between the PBS beam splitting prism and the concave reflecting mirror; the phase retarder is used for converting the first polarized light passing through twice into second polarized light.

According to an embodiment of the present application, the reference light system includes a light path turning component, a reference light relay lens group and a reference light imaging lens, which are sequentially arranged along a reference light path of the parallel light beam splitter; the optical path turning component is used for turning the optical path of the reference light so as to transmit the reference light from the parallel light beam splitter to the reference light relay lens group in a bending way; the reference light relay lens group is used for modulating the reference light from the light path turning component to form a reference light intermediate real image in front of the reference light imaging lens; the reference light imaging lens is used for modulating the reference light forming the intermediate real image of the reference light to form reference light with preset spatial angle distribution to face the HOE coating layer incident to the HOE substrate.

According to one embodiment of the present application, the parallel beam splitter is a BS beam splitter prism or a PBS beam splitter prism.

Drawings

Fig. 1 is a schematic structural diagram of a conventional catadioptric Birdbath optical system;

fig. 2 is a schematic structural diagram of a near-eye display device according to an embodiment of the present invention;

fig. 3 shows a variant implementation of the near-eye display device according to the above-described embodiment of the invention;

fig. 4 shows a block schematic diagram of an apparatus for manufacturing a holographic optical element according to an embodiment of the invention;

fig. 5 shows an example of an apparatus for manufacturing a holographic optical element according to the above-described embodiment of the present invention;

FIG. 6 is a schematic diagram showing light rays intercepting the recording of an exposure light path of a multi-field holographic optical element;

fig. 7 is a flow diagram of a method for manufacturing a holographic optical element according to an embodiment of the present invention;

fig. 8 is a schematic cross-sectional view showing an object light modulation step in the method for manufacturing a holographic optical element according to the above-described embodiment of the present invention;

fig. 9 shows a schematic cross-sectional flow diagram of a reference light modulation step in the method for manufacturing a holographic optical element according to the above-described embodiment of the present invention.

Description of the main element symbols: 1. a near-eye display device; 10. an image projector; 11. an image source; 12. an imaging lens; 20. a light-splitting element; 200. a flat plate light splitting member; 21. a half-reflecting and half-transmitting mirror; 22. a polarization beam splitter; 30. a holographic optical element; 300. a HOE substrate; 301. a light-transmitting substrate; 302. HOE coating; 40. 1/4 wave plate; 50. means for manufacturing a holographic optical element; 51. a light source projector; 52. a parallel beam splitter; 520. a BS beam splitter prism; 53. a reference light system; 530. a reference light intermediate real image; 531. an optical path turning component; 532. a reference light relay lens group; 533. a reference light imaging lens; 54. an object light system; 540. an object-light intermediate real image; 541. an object light relay lens group; 542. an object light imaging lens; 543. an object beam splitter; 5430. a PBS beam splitter prism; 544. a concave reflector; 545. a phase delay member.

The present invention is described in further detail with reference to the drawings and the detailed description.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

It will be understood that when an element is referred to as being "mounted on" another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present. When an element is referred to as being "secured to" another element, it can be directly secured to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.

Considering that the existing refraction and reflection type Birdbath optical system has only about 20% of actual transmittance and is extremely low, and the practicability of AR equipment is seriously influenced; and the image light reflected by the plane half-reflecting mirror is reflected by the concave reflecting mirror, and meanwhile, part of the image light can penetrate through the concave reflecting mirror and be watched by others, so that the problem of image leakage exists, and the use privacy of a user is influenced. The application provides a device for manufacturing a holographic optical element and a near-eye display device, which can replace a concave reflector in a traditional BB framework by using the specially manufactured holographic optical element so as to improve the actual transmittance, avoid image leakage and protect the use privacy of a user.

Specifically, referring to fig. 2, one embodiment of the present invention provides a near-eye display device 1, which may include an image projector 10, a light splitting element 20 disposed at a projection side of the image projector 10, and a holographic optical element 30 disposed at a reflection side of the light splitting element 20. The image projector 10 is used for projecting image light to the light-splitting element 20; the light splitting element 20 is used to reflect a portion of the light and transmit another portion of the light. The light splitting element 20 is configured to reflect the image light from the image projector 10 to be incident on the holographic optical element 30 with a predetermined spatial angle distribution, and the holographic optical element 30 is configured to redirect the image light incident with the predetermined spatial angle distribution to propagate to the light splitting element 20 and transmit the light incident with other spatial angle distributions. Thus, after the image light projected by the image projector 10 is reflected to the holographic optical element 30 by the light splitting element 20, the image light is redirected by the holographic optical element 30 to propagate all the way back to the light splitting element 20, and then passes through the light splitting element 20 to enter the human eye for imaging; meanwhile, the ambient light sequentially passes through the holographic optical element 30 and the light splitting element 20 to enter human eyes for imaging, so that the user can view a virtual image and a real environment at the same time to obtain an AR experience. It is to be understood that the preset spatial angular distribution referred to in the present application is identical or identical to the spatial angular distribution of the reference light when the holographic optical element 30 is manufactured; the other spatial angular distribution referred to in the present application may refer to a spatial angular distribution other than the preset spatial angular distribution, that is, the other spatial angular distribution is not identical to or different from the preset spatial angular distribution.

It should be noted that, according to the angle selection feature of the Holographic Optical Element (HOE), light rays facing to the HOE will be distributed by the HOE in a light redirection manner only if the light ray spatial angle distribution information of the reference light is satisfied (i.e., light rays consistent with the light ray spatial angle distribution of the reference light can be diffracted in a redirection manner by the HOE), while light sources in real environments are almost all incident to the HOE in a back direction from different angles, so that the transmittance of ambient light rays (i.e., light rays inconsistent with the light ray spatial angle distribution of the reference light) on the HOE reaches nearly 90%, which is far higher than the 40% transmittance of the concave reflector in the conventional BB architecture, thereby greatly improving the actual transmittance of the ambient light rays and greatly increasing the practicability of the near-eye display device. Meanwhile, since the spatial angular distribution of the light incident on the holographic optical element 30 after the image light projected by the image projector 10 of the present application is reflected by the light splitting element 20 is consistent with the spatial angular distribution of the light of the reference light when the holographic optical element 30 is manufactured, the image light incident on the holographic optical element 30 is totally diffracted back to the light splitting element 20 and then passes through the light splitting element 20 to enter the human eye, so that no image light passes through the holographic optical element 30, that is, no image light leaks, and the privacy of the user is effectively protected.

In addition, since the diffraction efficiency of the image reconstruction light upon incidence to the holographic optical element 30 is as high as 80% which is higher than the 60% reflectivity of the concave mirror in the conventional BB architecture, 80% of the image light incident to the holographic optical element 30 is redirected to be imaged, so that the image display efficiency of the near-eye display device 1 is improved.

More specifically, as shown in fig. 2, the image projector 10 may include an image source 11 for emitting image light and an imaging lens 12 for modulating light, the imaging lens 12 being disposed in an optical path between the image source 11 and the light splitting element 20 for modulating the image light from the image source 11 to propagate to the light splitting element 20.

Alternatively, the image source 11 may be, but is not limited to being, implemented as one of an LCD display element, an OLED display element, and a Micro LED display element.

Optionally, the imaging lens 12 may be, but is not limited to being, implemented as being composed of one or more lenses. It should be noted that the lens surface type of the imaging lens 12 can be implemented as one or more of a standard spherical surface, an aspheric surface, a free-form surface and a diffractive surface, which is not described herein again.

Alternatively, as shown in fig. 2, the light splitting element 20 may be, but is not limited to, implemented as a flat light splitting piece 200, the flat light splitting piece 200 and the holographic optical element 30 are arranged along the observation axis L of the near-eye display device 1, and the included angle between the flat light splitting piece 200 and the observation axis L is between 50 ° and 70 ° so that the human eye observes the virtual image and the real environment along the observation axis L.

Alternatively, the surface shape of the flat plate light splitter 200 may be, but is not limited to, implemented as one of a plane, a spherical surface, an aspherical surface, and a free-form surface.

Alternatively, the surface shape of the holographic optical element 30 may be, but is not limited to, implemented as a plane or a curved surface as long as the required light redirection can be achieved, and the description of the present application is omitted.

In one example of the present application, as shown in fig. 2, the flat light splitter 200 may be implemented as a half-reflecting and half-transmitting mirror 21 for reflecting 50% of light and transmitting 50% of light, i.e., the reflectivity R =50% and the transmittance T =50% of the flat light splitter 200. Of course, in other examples of the present application, the flat light splitter 200 may also perform partial reflection and partial transmission according to other ratios of the reflection-transmission ratio, which is not described in detail herein.

Illustratively, as shown in fig. 2, taking the transflective ratio of the transflective mirror 21 as 1:1 and the diffraction efficiency of the holographic optical element 30 as 80%, when the image light projected by the image projector 10 propagates to the

transflective mirror

21, 50% of the image light is reflected by the transflective mirror 21 to the holographic optical element 30 to be diffracted, so that 80% of the image light is reflected by the holographic optical element 30 to the transflective mirror 21 in a redirecting manner, and 50% of the image light is transmitted by the transflective mirror 21 to be incident into the human eye, so that 50% 80% 50% =20% of the image light is incident into the human eye, i.e. the image light efficiency of the near-eye display device 1 reaches 20%, which is higher than 50% 60% 50% =15% of the conventional BB architecture. Meanwhile, 90% of the ambient light passes through the holographic optical element 30 to propagate to the transflective lens 21, and then 50% of the ambient light passes through the transflective lens 21 to be incident to the human eye, so that 90% by 50% =45% of the ambient light is incident to the human eye, that is, the ambient light efficiency of the near-eye display device 1 reaches 45%, which is much higher than 40% by 50% =20% of the conventional BB architecture. In summary, the near-to-eye display device 1 of the present application has an actual transmittance of 45% for ambient light and a utilization rate of 20% for image light, both of which are higher than 20% and 15% of the conventional BB architecture, thereby greatly improving the light energy utilization rate and the practicability of the device; meanwhile, the holographic optical element 30 of the near-eye display device 1 can also block the image light from escaping forward to avoid leakage, thereby effectively protecting the use privacy of the user.

It is noted that fig. 3 shows a near-eye display device according to a variant embodiment of the present application in order to further improve the light energy utilization efficiency. This variant embodiment according to the present application differs from the above-described embodiment according to the present application in that: the light-splitting element 20 of the near-eye display device 1 may be implemented as a polarization beam splitter 22 for reflecting light of a first polarization and transmitting light of a second polarization; the near-eye display device 1 further comprises a 1/4 wave plate 40, the 1/4 wave plate 40 being disposed between the polarization splitting member 22 and the holographic optical element 30 for converting the twice-passed first polarized light into the second polarized light. It is understood that the polarization direction of the first polarized light of the present application is perpendicular to the polarization direction of the second polarized light, e.g. when the first polarized light is implemented as P-polarized light or S-polarized light, the second polarized light is implemented as S-polarized light or P-polarized light, respectively.

Thus, as shown in fig. 3, when the image light projected by the image projector 10 propagates to the

polarization beam splitter

22, 50% of the image light (image light with the first polarization state) is reflected by the polarization beam splitter 22 to propagate to the holographic optical element 30 to be diffracted after passing through the 1/4 wave plate 40 for the first time, so that 80% of the image light is reflected by the holographic optical element 30 in a redirecting manner to propagate back to the polarization beam splitter 22 after passing through the 1/4 wave plate 40 (converted into image light with the second polarization state) for the second time, and then 100% of the image light (image light with the second polarization state) is transmitted through the flat plate beam splitter 200 to be incident into the human eye, so that 50% 80% 100% 40% of the image light is incident into the human eye in total, that the image light efficiency of the near-eye display device 1 is 40%, which is far higher than 50% 60% 15% of the conventional BB architecture. Meanwhile, the ambient light efficiency of the near-eye display device 1 is still kept at 45%, which is much higher than 40% by 50% =20% of the conventional BB architecture, so that the light energy utilization rate is further improved. It will be appreciated that if the image light emitted by the image source 11 of the image projector 10 itself has the first polarization state, the image light efficiency of the near-eye display device 1 will reach a surprising 80%, and the description thereof is omitted here.

It is noted that, since the near-eye display device 1 of the present application can improve the utilization rate of light energy and protect the user's privacy of use at the same time, the holographic optical element 30 specially made for the present application can diffract all the image light in accordance with the light ray spatial angle distribution of the reference light back to the light splitting element 20 and allows nearly 90% of the ambient light to pass through; it is therefore yet another key aspect of the present application how to manufacture a holographic optical element 30 that satisfies the above conditions.

Specifically, fig. 4 and 5 illustrate an apparatus 50 for manufacturing a holographic optical element according to one embodiment of the present application for coherent recording of object and reference light at a HOE substrate 300 to form the aforementioned holographic optical element 30. The apparatus 50 for manufacturing a holographic optical element may include a light source projector 51 for projecting parallel lights of different angles, a parallel light beam splitter 52 disposed at a projection side of the light source projector 51, a reference light system 53, and an object light system 54. The parallel beam splitter 52 is used to split one path of parallel light from the light source projector 51 into reference light propagating along a reference light path and object light propagating along an object light path. The reference light system 53 is disposed in the reference light path of the collimator 52, and is used for modulating the reference light from the collimator 52 to form a predetermined spatial angle distribution of the reference light incident on the HOE substrate 300; the object light system 54 is disposed on the object light path of the parallel beam splitter 52, and is configured to modulate the object light from the parallel beam splitter 52 to form object light with different angle parallel distributions to be incident on the HOE substrate 300, so that the reference light with a predetermined spatial angle distribution and the object light with different angle parallel distributions are subjected to interference recording on the HOE substrate 300, and the HOE substrate 300 forms the holographic optical element 30.

It should be noted that the light spatial angle distribution of the reference light incident on the HOE substrate 300 mentioned in the present application is consistent with the light spatial angle distribution of the image light reflected to the holographic optical element 30 via the light splitting element 20 in the near-eye display device 1. It is understood that the light ray spatial angle distribution of the image light reflected to the holographic optical element 30 via the light splitting element 20 in the near-eye display device 1 of the present application is equivalent to the light ray spatial angle distribution of the image light reflected to the concave mirror via the flat half mirror in the conventional catadioptric Birdbath optical system.

More specifically, as shown in fig. 5, the object optical system 54 may include an object light relay lens group 541, an object light imaging lens 542, an object light splitter 543, and a concave mirror 544, which are arranged in this order along the object light path of the parallel light splitter 52. The object light relay lens group 541 is configured to modulate the object light from the collimator beam splitter 52 to form an object light intermediate real image 540 before the object light imaging lens 542; the object light imaging lens 542 is configured to modulate object light forming the object light intermediate real image 540 to form object light with a predetermined spatial angle distribution; the object beam splitter 543 is configured to reflect the object beam from the object beam imaging lens 542 to be incident on the concave mirror 544; the concave reflector 544 is used for reflecting the object light with a predetermined spatial angle distribution to form object light with different angle parallel distributions; the object beam splitter 543 is further used for transmitting object beams distributed in parallel at different angles to be incident back to the HOE substrate 300. It is understood that the spatial angular distribution of the object light incident on the concave mirror 544 is consistent with the spatial angular distribution of the reference light incident on the HOE substrate 300; in other words, the light spatial angular distribution of the object light incident on the concave mirror 544 and the light spatial angular distribution of the image light reflected to the holographic optical element 30 via the light splitting element 20 in the near-eye display apparatus 1 are consistent, so as to ensure that the holographic optical element 30 is formed to meet the requirements of the near-eye display apparatus 1.

Optionally, as shown in fig. 5, the object beam splitter 543 may be, but is not limited to be, implemented as a PBS beam splitter prism 5430, and the object optical system 54 further includes a phase delay member 545 disposed between the PBS beam splitter prism 5430 and the concave mirror 544; the PBS splitting prism 5430 is used to reflect the first polarized light and transmit the second polarized light; the phase retarder 545 functions to convert the twice-passed light of the first polarization into light of the second polarization. Thus, the first polarized light in the object light from the object light imaging lens 542 is reflected by the PBS splitter prism 5430 to pass through the phase retardation member 545 for the first time and enter the concave mirror 544, then reflected by the concave mirror 544 to pass through the phase retardation member 545 for the second time and be converted into the second polarized light, and further pass through the PBS splitter prism 5430 to enter the HOE substrate 300. It is understood that in other examples of the present application, the object beam splitter 543 may be implemented as a BS beam splitter prism, which can reduce the utilization rate of the object beam but does not need to additionally provide the phase retarder 545, and the manufacturing requirement of the holographic optical element 30 can still be met, which is not described herein again.

Alternatively, the phase delay 545 may be implemented as a 45 ° 1/4 wave plate.

Alternatively, as shown in fig. 5, the parallel beam splitter 52 may be, but is not limited to, implemented as a BS beam splitter prism 520, and the BS beam splitter prism 520 is configured to reflect 50% of the parallel light to form a reference light path and transmit 50% of the parallel light to form an object light path. It is understood that, in other examples of the present application, the parallel beam splitter 52 may also be implemented as a PBS beam splitting prism, and is configured to reflect the second polarized light in the parallel light to form a reference light path, and transmit the first polarized light in the parallel light to form an object light path, so as to improve the light energy utilization rate of the object light, and still achieve the manufacturing requirement of the holographic optical element 30, which is not described herein again.

According to the above-mentioned embodiment of the present application, as shown in fig. 5, the reference light system 53 may include a light path turning component 531, a reference light relay lens group 532 and a reference light imaging lens 533 arranged in sequence along the reference light path of the parallel light beam splitter 52, the light path turning component 531 being configured to turn the reference light path to curvedly transmit the reference light from the parallel light beam splitter 52 to the reference light relay lens group 532; the reference light relay lens group 532 is used for modulating the reference light from the optical path turning component 531 to form a reference light intermediate real image 530 before the reference light imaging lens 533; the reference light imaging lens 533 is configured to modulate the reference light forming the reference light intermediate real image 530 to form a predetermined spatial angle distribution of the reference light to face the HOE substrate 300.

Alternatively, the optical path turning member 531 may include a pair of reflective prisms arranged correspondingly to turn the optical path of the reference light of the parallel beam splitter 52 by 180 ° so that the reference light and the object light are incident from opposite sides of the HOE substrate 300, respectively, to interfere.

Alternatively, as shown in fig. 5, the HOE substrate 300 may include a light-transmissive substrate 301 and a HOE coating 302 disposed on the light-transmissive substrate 301; the HOE coating 302 of the HOE substrate 300 faces the reference light system 53 such that the reference light modulated to form a predetermined spatial angular distribution by the reference light system 53 is directly incident to the HOE coating 302; the HOE coating 302 of the HOE substrate 300 faces away from the object light system 54, so that object light modulated by the object light system 54 to form different angle parallel distributions firstly passes through the transparent substrate 301 and then enters the HOE coating 302. Thus, a predetermined spatial angular distribution of reference light faces the HOE coating 302 incident on the HOE substrate 300, and different angular parallel distributions of object light face away from the HOE coating 302 incident on the HOE substrate 300, thereby interfering at the HOE coating 302 to be recorded by the HOE coating 302 to form the holographic optical element 30.

In other words, as shown in fig. 6, the holographic optical element 30 of the present application includes a transparent substrate 301 and an HOE coating 302 disposed on the transparent substrate 301, wherein the HOE coating 302 faces the light splitting element 20, and the HOE coating 302 records information of interference between reference light with a predetermined spatial angle distribution and object light with different angular parallel distributions.

Notably, the material of the HOE coating 302 may be, but is not limited to being, implemented as a high molecular polymer; the material of the light-transmitting substrate 301 may be, but is not limited to, implemented as transparent glass. In addition, a schematic diagram of intercepting light during the recording process of the multi-view HOE exposure optical path is shown in fig. 6, wherein the exit pupil is the exit pupil in the conventional BB framework design optical path, that is, the position of the human eye.

It is worth mentioning that fig. 7 illustrates a manufacturing method for a holographic optical element according to an embodiment of the present application, which may include the steps of:

s100: splitting parallel light with different angles into a reference light path and an object light path respectively;

s200: modulating the reference light into reference light with a preset spatial angle distribution to be incident to the HOE substrate;

s300: modulating the road object light into object light distributed in parallel at different angles to be incident to the HOE substrate; and

s400: and recording information of interference between reference light distributed at a preset spatial angle and object light distributed in parallel at different angles through the HOE substrate to form the holographic optical element.

It is to be noted that the order between step S200 and step S300 in the manufacturing method for a holographic optical element of the present application is not sequential and is performed in parallel.

According to an example of the present application, as shown in fig. 8, the step S300 may include the steps of:

s310: modulating the path light to form an intermediate real image of the path light;

s320: modulating object light forming the intermediate real image of the object light to form object light distributed at a preset spatial angle; and

s330: reflecting the object light with preset spatial angle distribution to form object light with different angle parallel distribution to be incident back to the HOE coating of the HOE substrate.

According to an example of the present application, as shown in fig. 9, the step S200 may include the steps of:

s210: turning the path of reference light;

s220: modulating the turned reference light to form a reference light intermediate real image;

s230: modulating the reference light forming the intermediate real image of the reference light to form a predetermined spatial angle distribution of the reference light facing the HOE coating layer incident on the HOE substrate.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above examples only represent some embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A near-eye display device, comprising:

an image projector for projecting image light;

2. A near-eye display device as claimed in claim 1 wherein the face shape of the holographic optical element is a flat or curved surface.

3. The near-eye display device of claim 1 wherein the image projector comprises an image source for emitting image light and an imaging lens for modulating light, the imaging lens being disposed in an optical path between the image source and the light-splitting element for modulating image light from the image source for propagation to the light-splitting element.

4. The near-eye display device of claim 1, wherein the light splitting element is a flat plate light splitting element, the flat plate light splitting element and the holographic optical element are arranged along a viewing axis of the near-eye display device, and an angle between the flat plate light splitting element and the viewing axis is between 50 ° and 70 °.

5. A near-eye display device according to claim 4 wherein the plate beamsplitter is a half mirror for reflecting 50% of the light and transmitting 50% of the light.

6. A near-eye display device as claimed in claim 1 wherein the light splitting element is a polarization beam splitter for reflecting light of a first polarization and transmitting light of a second polarization, the near-eye display device further comprising a 1/4 wave plate disposed between the polarization beam splitter and the holographic optical element for converting twice-passed light of the first polarization into light of the second polarization.

7. A near-eye display device as claimed in any one of claims 1 to 6 wherein the holographic optical element comprises a light transmissive substrate and an HOE coating disposed on the light transmissive substrate, the HOE coating facing the light splitting element and recording information of interference of the reference light of the predetermined spatial angular distribution with object light of different angular parallel distributions.

8. An apparatus for manufacturing a holographic optical element, comprising:

and the object optical system is arranged on an object optical path of the parallel beam splitter and is used for modulating the object light from the parallel beam splitter to form object light which is distributed in parallel at different angles and is incident to the HOE substrate, so that the reference light distributed at a preset spatial angle and the object light distributed in parallel at different angles are subjected to interference recording at the HOE substrate, and the HOE substrate forms a holographic optical element.

9. The apparatus of claim 8, wherein the object light system comprises an object light relay lens group, an object light imaging lens, an object light splitter, and a concave mirror arranged in this order along the object light path of the parallel light splitter; the object light relay lens group is used for modulating the object light from the parallel beam splitter to form an object light intermediate real image in front of the object light imaging lens; the object light imaging lens is used for modulating object light forming the intermediate real image of the object light to form object light distributed in a preset space angle; the object light splitter is used for reflecting the object light from the object light imaging lens to be incident to the concave reflecting mirror; the concave reflector is used for reflecting object light distributed at a preset space angle to form object light distributed in parallel at different angles; the object beam splitter is further configured to transmit object beams distributed in parallel at different angles to be directed away from the HOE coating layer incident on the HOE substrate.

10. The apparatus for manufacturing a holographic optical element according to claim 9, wherein said object beam splitter is a PBS beam splitting prism for reflecting a first polarized light and transmitting a second polarized light; and the object optical system further comprises a phase delay member disposed between the PBS beam splitting prism and the concave reflecting mirror; the phase retarder is used for converting the first polarized light passing through twice into second polarized light.

11. The apparatus of claim 8, wherein the reference light system comprises a light path turning member, a reference light relay lens group, and a reference light imaging lens, which are sequentially arranged along the reference light path of the parallel light beam splitter; the optical path turning component is used for turning the optical path of the reference light so as to transmit the reference light from the parallel light beam splitter to the reference light relay lens group in a bending way; the reference light relay lens group is used for modulating the reference light from the optical path turning component to form a reference light intermediate real image in front of the reference light imaging lens; the reference light imaging lens is used for modulating the reference light forming the intermediate real image of the reference light to form reference light with preset spatial angle distribution to face the HOE coating layer incident to the HOE substrate.

12. The apparatus for manufacturing a holographic optical element according to claim 8, wherein said parallel beam splitter is a BS beam splitter prism or a PBS beam splitter prism.