CN217467364U

CN217467364U - Projection system based on focusing super lens and equipment with same

Info

Publication number: CN217467364U
Application number: CN202221714460.7U
Authority: CN
Inventors: 郝成龙; 谭凤泽; 朱瑞; 朱健
Original assignee: Shenzhen Metalenx Technology Co Ltd
Current assignee: Shenzhen Metalenx Technology Co Ltd
Priority date: 2022-07-05
Filing date: 2022-07-05
Publication date: 2022-09-20
Anticipated expiration: 2032-07-05

Abstract

The present disclosure relates to the field of optical superlenses, and more particularly, to a focusing superlens based projection system and an apparatus having the same. The focusing superlens based projection system includes an image generation unit; a superlens optical device for focusing, disposed downstream of the image generating unit on the optical path; under the working condition of the projection system, the super-lens optical device for focusing can adjust the distance between the displayed real image and the eye pupil or the equivalent focal length of the projection system in real time. The utility model discloses a super lens optical device for focusing, real-time adjustment shows the distance between real image and the eye pupil or projection system's equivalent focal length to alleviate or eliminate the focusing conflict. Meanwhile, the projection reduces the complexity of the system, reduces the volume of the system and improves the robustness of the system through a super-lens optical device for focusing. On the other hand, the response speed is high, the focusing conflict is solved better, and the user experience is improved.

Description

Projection system based on focusing super lens and equipment with same

Technical Field

The present disclosure relates to the field of optical superlenses, and more particularly, to a focusing superlens based projection system and an apparatus having the same.

Background

Virtual Reality (VR) or Augmented Reality (AR) is a display technology that increases the user's sensory experience by deviation or superimposition of projected images. With the popularization of VR and AR, users have increasingly heightened VR/AR devices.

Existing VR/AR devices are plagued by a convergence accommodation conflict (also known as a focus conflict). The convergence accommodation conflict of the existing VR/AR device means that the convergence distance (the distance from the convergence point of the respective visual lines of the two eyes to the line of the two eyes) and the accommodation distance (the distance from the eyes to the observation object) of the user are inconsistent. And when the user does not use the VR/AR equipment, the observation object is a real object. At this time, the convergence distance of the user's visual line and the accommodation distance are dynamically coordinated, thereby clearly imaging on the retina. And when the user uses the VR/AR equipment, the observation object is a projection image of the VR/AR equipment. At this time, the adaptive distance of the user is fixed, and the convergence distance of the visual lines dynamically changes, so that the adaptive distance and the convergence distance cannot be dynamically coordinated, and the visual fatigue and dizziness of the user occur.

Therefore, there is a need for a projection system to mitigate the vergence adjustment conflict for VR/AR devices.

SUMMERY OF THE UTILITY MODEL

To the above-mentioned defect of prior art, the utility model provides a projection system based on super lens of focusing and have its equipment realizes eliminating or alleviateing the focusing conflict based on super lens of phase transition, has solved above-mentioned technical problem.

In order to achieve the above object, the utility model provides a following technical scheme:

the utility model provides a projection system based on super lens of focusing, include:

an image generating unit;

a superlens optical device for focusing, disposed downstream of the image generating unit on the optical path;

under the working condition of the projection system, the superlens optical device for focusing can adjust the distance between the displayed real image and the eye pupil or the equivalent focal length of the projection system in real time.

Optionally, the superlens optical device for focusing is a MEMS micro-movement based superlens group, wherein the MEMS micro-movement based superlens group includes: at least two superlenses; at least one micro-electromechanical actuator for moving at least one superlens of the superlens group; wherein the at least one superlens is movable by the at least one microelectromechanical actuator in the direction of the light propagation path such that the focal length of the superlens group is varied.

Optionally, the MEMS micro-motion based superlens group further comprises: a MEMS flexible suspension coupled with at least one of the at least two superlenses;

the MEMS flexible suspension is configured to elastically deform in a direction parallel to the optical path.

Optionally, each of the at least two superlenses comprises a first conductive layer, an electric actuation layer and a nanostructure, wherein the electric actuation layer is disposed on one side of the first conductive layer; the nano structure is arranged on one side of the electric actuating layer far away from the first conducting layer;

the first conductive layer is configured to manipulate an electric field to drive the displacement of the electrically actuated layer along the optical path.

Optionally, the superlens optical arrangement for focusing comprises at least one phase-change superlens, wherein the phase-change superlens comprises a phase-change element and an actuation element; the phase change element comprises a first electrode and a second electrode which are arranged at intervals; the first electrode and the second electrode are electrically connected through the middleware of the phase change unit;

a potential difference can be formed between the first electrode and the second electrode, and the temperature of the intermediate member between the first electrode and the second electrode is changed by electrothermal conversion so that the temperature of the phase change element can be changed.

Optionally, the superlens optical device for focusing further comprises: a first metal reflective layer;

the phase change element is positioned on the light reflecting side of the first metal reflecting layer;

the first electrode and the second electrode are respectively electrically connected with the first metal reflecting layer and are positioned on two sides of the phase change element.

Optionally, the superlens optical device for focusing comprises at least one phase-change superlens, wherein the phase-change element comprises a substrate, a nanostructure, a first electrode layer, a filler, and a second electrode layer;

the nanostructure array is arranged on one side of the substrate;

the first electrode layer and the filler are sequentially filled among the nano structures layer by layer along the direction far away from the substrate; and the sum of the heights of the first electrode layer and the filler is greater than or equal to the height of the nanostructure;

the second electrode layer is arranged on one side, far away from the first electrode layer, of the filler. Optionally, the phase change super lens is a transmissive phase change super lens, and is configured to adjust a distance between the displayed real image and an eye pupil or an equivalent focal length of the projection system in real time.

Optionally, the display device further comprises a projection lens, wherein the projection lens is arranged at the downstream of the super lens optical device for focusing on the light path and is used for projecting the display real image formed by the image generation unit through the super lens optical device for focusing.

Optionally, the optical system further comprises a mirror, and the mirror is arranged between the super-lens optical device for focusing and the projection lens on the optical path.

Optionally, the projection lens comprises a refractive lens or a superlens with chromatic aberration correction.

Optionally, the image generating unit comprises a micro light emitting diode display array and a turntable filter;

the micro light emitting diode display array is used for generating light with at least one color;

the turntable filter is used for selecting the frequency of the light emitted by the micro light-emitting diode array.

Optionally, the image generating unit includes at least two discrete lasers, at least two dichroic mirrors, a prism, and a digital micromirror device, which are sequentially arranged along the optical path;

the at least two dichroic mirrors are used for carrying out frequency selection and light path turning on laser generated by at least two separated lasers;

the digital micromirror device is used to modulate light reflected by the prism according to the projected image.

Optionally, the image generating unit comprises two blue lasers, a fluorescent disc, at least two dichroic mirrors, a prism and a digital micromirror device;

one of the two blue lasers is used for generating blue laser light, and the other of the two blue lasers is used for irradiating the fluorescent disc to generate at least two laser lights with different wavelengths from the blue laser light;

the two dichroic mirrors are used for carrying out frequency selection and light path turning on the blue laser and the at least two lasers;

Optionally, the image generating unit includes at least two discrete narrow-band light emitting diodes, at least two dichroic mirrors, a prism, and a digital micromirror device, which are sequentially arranged along the optical path;

the at least two dichroic mirrors are used for carrying out frequency selection and light path turning on laser generated by the at least two separated narrow-band light-emitting diodes;

The present invention also provides an apparatus comprising a focusing superlens based projection system as described above.

The beneficial effects of the utility model are that: the embodiment of the utility model provides a projecting system based on super lens of focusing through the super lens optical device who is used for the focusing, adjusts the equivalent focal length that shows distance between real image and the eye pupil or projecting system in real time to alleviate or eliminate the focusing conflict. Meanwhile, the projection reduces the complexity of the system, reduces the volume of the system and improves the robustness of the system through a super-lens optical device for focusing. On the other hand, the super-lens optical device for focusing has high response speed, better focusing conflict solving effect and improved user experience.

Drawings

For a better understanding of the features and technical content of the present invention, reference should be made to the following detailed description of the present invention and accompanying drawings, which are provided for the purpose of illustration and description and are not intended to limit the present invention.

FIG. 1 is an alternative schematic diagram configuration of a focusing superlens based projection system of the present invention;

fig. 2 is a schematic diagram of a super lens group of a projection system based on a focusing super lens, in which an arrow in the figure indicates a moving direction of a second super lens, and a dotted line indicates an optical axis, where the focal length of the super lens group is the minimum;

fig. 3 is a schematic diagram of a maximum focal length of a super lens group of a projection system based on a focusing super lens of the present invention, wherein an arrow in the diagram indicates a moving direction of a second super lens, and a dotted line indicates an optical axis;

fig. 4 is a schematic view of a minimum focal length in the case that the super-lens optical device for focusing of the projection system based on the focusing super-lens of the present invention is a phase change super-lens;

fig. 5 is a schematic diagram of the maximum focal length when the super-lens optical device for focusing of the projection system based on the focusing super-lens of the present invention is a phase change super-lens;

fig. 6 is a schematic view of a minimum focal length when the phase change superlens of the projection system based on the focusing superlens of the present invention is a reflective electrically controlled phase change superlens;

fig. 7 is a schematic view of a maximum focal length when the phase change super lens of the projection system based on the focusing super lens of the present invention is a reflective electrically controlled phase change super lens;

FIG. 8 is a schematic view of a focusing superlens based projection system including a projection lens according to the present invention;

FIG. 9 is a schematic view of a focusing superlens based projection system including a mirror according to the present invention based on FIG. 8;

FIG. 10 is a schematic view of a super-surface structure being a regular hexagon;

FIG. 11 is a schematic view of a square super-surface structure;

FIG. 12 is a schematic view of a super-surface structure with a fan shape;

FIG. 13 is a schematic view of a nanocylinder;

fig. 14 is a schematic diagram of a nanofin;

FIG. 15 is a schematic diagram illustrating an alternative configuration of a phase change superlens provided by an embodiment of the present application;

FIG. 16 is a schematic diagram illustrating an alternative structure of a phase-change superlens provided by an embodiment of the present application;

FIG. 17 is a schematic diagram illustrating yet another alternative structure of a phase-change superlens provided by an embodiment of the present application;

FIG. 18 is a schematic diagram illustrating an alternative phase change superlens structure provided by an embodiment of the present application;

FIG. 19 is a schematic diagram illustrating an alternative structure of an image generating unit according to an embodiment of the present application;

FIG. 20 is a schematic diagram showing an alternative structure of an image generating unit provided in an embodiment of the present application;

FIG. 21 is a schematic diagram illustrating an alternative structure of an image generating unit provided in an embodiment of the present application;

fig. 22 shows an alternative structural diagram of an image generating unit provided in an embodiment of the present application.

Reference numerals:

1. an image generating unit;

2. a superlens optical device for focusing; 21. a first superlens; 22. a second superlens;

3. a projection lens; 4. a middle image plane; 5. an eye pupil; 6. a mirror;

101. a first electrode; 102. a second electrode; 103. a connecting layer; 201. a nanostructure; 502. A first insulating layer; 504. a second insulating layer; 60. a filler; 70. a substrate.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the application, as detailed in the appended claims.

The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present application. The word "if" as used herein may be interpreted as "at … …" or "when … …" or "in response to a determination", depending on the context. The features of the following examples and embodiments may be combined with each other without conflict.

In the prior art, a time multiplexing scheme is generally used for solving the problem of focusing conflict of VR/AR equipment. The two ways involved in time multiplexing are screen adjustment and projection lens adjustment, respectively.

In the technical scheme of adjusting a screen to solve a focusing conflict in the prior art, a high-frequency moving device is generally arranged on the screen, and the screen is moved at different times by using the high-frequency moving device, so as to dynamically adjust an adaptive distance. However, the presence of high frequency moving devices increases the complexity of the projection system and the size of the projection system. Because VR devices corresponding to VR technology need to be worn on the head of a user, the projection system needs to be miniaturized and light-weighted to improve comfort of the user.

In the technical scheme of adjusting the projection lens in the prior art, a liquid lens is adopted to adjust the focal length. A liquid lens is an optical element made of a liquid whose refractive index or surface curvature is changed by a voltage to change the optical properties of the liquid. Due to the limitation of liquid lens materials, the response time of the current liquid lens is generally about 10ms, and the problem of focal plane stroboscopic is more prominent when the problem of focusing conflict is solved.

Based on the above reasons, the inventors found that a superlens for focusing can solve the disadvantages of the existing time multiplexing method, and therefore, the inventors proposed a projection system based on a focusing superlens.

Referring to fig. 1 to 9, a focusing superlens-based projection system includes: an image generating unit 1 and superlens optics 2 for focusing.

As shown in fig. 1, the image generating unit 1 is configured to generate at least one beam of light according to image information to be projected.

According to an embodiment of the present application, referring to fig. 19, the image generating unit 1 includes a micro light emitting diode display array and a rotary disk filter.

The Micro light-emitting diode (Micro LED) display array is an integrated LED array, and a distance between adjacent LED pixels in the array is in the order of 10 micrometers. The micro light emitting diode display array is used for generating light with at least one color.

The carousel filter sets up in the low reaches of little emitting diode display array on the light path, and the light that is jetted out by little emitting diode display array through the carousel filter, the carousel filter carries out the frequency selection to the light according to the image information that wants the projection, and the light that sees through the carousel filter gets into the superlens optical device 2 that is used for the focusing and is used for the formation of image. Typically, a motor is used to control the rotation of the rotating disc filter.

According to an embodiment of the present application, referring to fig. 20, the image generating unit 1 includes at least two discrete lasers, at least two Dichroic Mirrors (Dichroic Mirrors), a Prism (Prism), and a Digital Micromirror Device (DMD) sequentially arranged along an optical path.

Where the number of lasers is at least two, capable of emitting light of different colors, preferably three lasers, e.g. three lasers, each emitting light of one color, the three colors being the primary colors red, green and blue, respectively.

The dichroic mirrors are used for performing frequency selection and optical path turning on laser light generated by at least two separate lasers, the number of the dichroic mirrors is at least two, the dichroic mirrors are arranged on the optical path and are arranged at the downstream of the lasers, the dichroic mirrors correspond to the lasers one by one, and for example, when the number of the lasers is three, the number of the dichroic mirrors is three.

And a digital micromirror device for modulating the light reflected by the prism according to the projected image. Generally, the digital micromirror device includes reflective elements arranged in an array, and the reflective elements are controlled to be turned on according to image information to reflect light to be transmitted to a projection optical path.

And the prism is arranged on the optical path and at the downstream of the dichroic mirror and the digital micromirror device and used for reflecting the light rays emitted from the dichroic mirror to the DMD and transmitting the reflected light rays of the DMD to a projection optical path. Specifically, the prism reflects light with the frequency selected by the dichroic mirror to the digital micromirror device, and enables light reflected by the reflection unit which is started by the digital micromirror device to enter the projection light path, and reflected light of the reflection unit which is in a closed state and the reflection unit in an intermediate transition state in the digital micromirror device is shielded, so that the proportion of light beams with different frequencies passing through the prism is regulated according to the color of an image to be projected. According to an embodiment of the present application, referring to fig. 21, the image generating unit 1 includes two blue lasers, a fluorescent disc, at least two dichroic mirrors, a prism, and a digital micromirror device.

Wherein one of the two blue lasers is used for generating blue laser light, and the other is used for irradiating the fluorescent disc to generate at least two laser lights with different wavelengths from the blue laser light.

The dichroic mirrors are at least two in number, are arranged on the downstream of the blue laser on the light path, and are used for carrying out frequency selection and light path turning on the blue laser and at least two lasers which are the same as the blue laser.

The prism and the digital micromirror device function are not described in detail above.

According to an embodiment of the present application, referring to fig. 22, the image generation unit 1 includes at least two discrete narrow-band light emitting diodes, at least two dichroic mirrors, a prism, and a digital micromirror device, which are sequentially arranged along an optical path;

the number of the narrow-band light-emitting diodes is at least two, preferably three, and the narrow-band light-emitting diodes respectively emit red light, green light and blue light.

The quantity of the dichroic mirrors is at least two, the dichroic mirrors correspond to the narrow-band light-emitting diodes one by one and are used for carrying out frequency selection and light path turning on laser generated by the narrow-band light-emitting diodes.

It should be noted that in some alternative embodiments of the present application, the ratio of the bandwidth of the narrow-band laser to the center wavelength is less than 0.1. Preferably, the ratio of the bandwidth of the narrow band laser to the center wavelength is less than 0.03. In the above-described configuration of the image generating unit 1, it is further preferable that the micro-light emitting diode display array and the rotary disk filter are arranged so as to realize the high luminance and small pixel image generating unit 1.

A superlens optical device 2 for focusing is disposed downstream of the image generating unit 1 on the optical path to modulate the light from the image generating unit 1. Optionally, the operating band of the superlens optics 2 used for focusing is the visible band (e.g., 400nm to 700 nm).

When the projection system is in operation, the superlens optical device 2 for focusing can adjust the distance between the displayed real image and the eye pupil or the equivalent focal length of the projection system in real time.

In this embodiment, the superlens optical device 2 for focusing adjusts the focal length of the outgoing light, so that the focal length of the superlens optical device 2 for focusing is different between the first time and the second time, and the distance between the displayed real image and the eye pupil or the equivalent focal length of the projection system is adjusted, thereby reducing or eliminating the focusing conflict, wherein the first time and the second time may be continuous time or discontinuous time, that is, the superlens optical device 2 for focusing can not only be adjusted in real time, but also be adjusted at certain time intervals. The projection system of the superlens optical device 2 for focusing has the advantages of reducing the complexity of the projection system, reducing the volume and having higher robustness. In addition, since the material of the superlens optical device 2 for focusing is not liquid, the response time can be faster than that of a liquid lens, and the user experience is improved.

As shown in fig. 2 and 3, in one embodiment, a superlens optical apparatus 2 for focusing includes: a superlens group consisting of at least two superlenses, the focal length of the superlens group can be in a preset focal length f _min And f _max And adjusting the range in a reciprocating way.

The number of the superlenses forming the superlens group can be set according to requirements, and for example, three or four superlenses can be selected.

Preferably, the superlens group includes two superlenses, a first superlens 21 and a second superlens 22, respectively, and is disposed downstream of the image generating unit 1 on the optical path.

One of the first and

second superlenses

21 and 22 is used as a reference, and the other superlens is moved back and forth on the optical path, thereby adjusting the focal length.

For example, in the design scheme of the screen relay real image adjustable time-multiplexed near-eye projection, the emergent light of the image generating unit 1 can form an intermediate image surface 4 at the focus of the first superlens 21 after sequentially passing through the second superlens 22 and the first superlens 21.

Wherein the second superlens 22 isThe focal length of the second superlens 22 is f in the case of reciprocating within a prescribed moving distance range _min And f _max With the second superlens 22 being moved. That is, the image generating unit 1 at the first time has a focal length f of the second superlens 22 _min The emergent light during the process sequentially passes through the second super lens 22 and the first super lens 21 and then converges at the focus of the first super lens 21 to form a first intermediate image surface; the image generation unit 1 at the second time has a focal length f of the second superlens 22 _max Then, the emergent light sequentially passes through the second superlens 22 and the first superlens 21, and then converges at the focus of the first superlens 21, so as to form a second intermediate image plane. Since the second superlens 22 is located at different positions in the reciprocating motion of the second superlens 22 at the first time and the second time, the distances between the relay real image formed by the first intermediate image plane 4 and the second intermediate image plane 4 and the eye pupil 5 are different, so that different depths can be generated, and focusing conflicts can be reduced or eliminated.

It should be noted that the superlens group is a superlens group based on Micro-Electro Mechanical System (MEMS) Micro-motion, and specifically includes at least one Micro-electromechanical actuator, and the Micro-electromechanical actuator moves along the direction of the light propagation path, as shown in fig. 2 and 3, and the Micro-electromechanical actuator moves the second superlens 22, so that the focal length of the superlens group changes, thereby adjusting the distance between the display real image and the eye pupil or the equivalent focal length of the projection System.

In particular, a microelectromechanical actuator is an actuator that can be controlled directly or indirectly by signals, such as electrical and/or optical signals.

It should be further noted that the superlens group based on MEMS micro-motion further includes: a MEMS flexible suspension coupled to at least one of the at least two superlenses, the MEMS flexible suspension configured to elastically deform in a direction parallel to the optical path.

Specifically, the MEMS flexible suspension is coupled to the second superlens 22, and it is understood that the number of the MEMS flexible suspensions may be at least two, and the MEMS flexible suspensions are separately disposed on two opposite sides of the second superlens 22, and are driven by the micro-electromechanical actuator to be elastically deformed to move the second superlens 22 connected thereto. Alternatively, the MEMS flexible suspension may amplify the displacement of the microelectromechanical actuator by elastic deformation.

In this embodiment, the focal length of the second superlens 22 is changed by changing the focal length of the second superlens 22 at the first time and the second time, so that the focal length of the superlens group is changed, and the focusing conflict is reduced or eliminated. The super lens group based on MEMS micro-movement has the characteristic of small volume, so that the whole volume of the projection system based on the focusing super lens is reduced, and the miniaturization requirement is met.

In one embodiment, each of at least two superlenses included in the superlens group includes a first conductive layer, an electric actuating layer and a nanostructure, wherein the electric actuating layer is disposed on one side of the first conductive layer; the nano structure is arranged on one side of the electric actuating layer far away from the first conducting layer; the first conductive layer is configured to manipulate an electric field to drive the displacement of the electrically actuated layer along the optical path.

Optionally, the electric actuation layers of any two adjacent superlenses in the superlens group constitute two plates of a capacitor. At this time, the voltage at the two ends of the capacitor is controlled by the first conductive layer, so that the distance between the two polar plates (electric actuating layer) of the capacitor is changed, and the focal length of the super lens group is changed. Optionally, the electrically actuated layer is the same layer as the first electrically conductive layer. Optionally, the electrical actuation is a film of a different material than the first conductive layer. Preferably, any superlens in the superlens group is adjustable in position, and the rest superlenses are fixed in position, so that the complexity of the system is reduced, and the robustness of the system is improved. The super-lens group provided by the embodiment of the application can realize the change of focal length through the above mode, further realize the modulation of light, adjust the distance between the display real image on the intermediate image plane 4 and the eye pupil 5 or the equivalent focal length of the projection optical device in real time, and thereby eliminate or reduce focusing conflict.

In one embodiment, shown in FIGS. 4 and 5, the superlens optics 2 for focusing includes at least one phase change superlens constructed based on a phase change material. Generally, a phase change superlens includes an actuation element and a phase change element. Wherein the actuation element is to apply independent actuation to the phase change element to change a phase change state of the phase change element. The phase change element includes at least one nanostructure made of a phase change material, and the phase change state of the phase change material includes a crystalline state or an amorphous state.

It will be appreciated that the focal length adjustment may be achieved by a phase change superlens, which is a transmissive phase change superlens, for adjusting in real time the distance between the displayed real image and the eye pupil or the equivalent focal length of the projection system.

As shown in FIGS. 6 and 7, in one embodiment, the phase change superlens is a reflective phase change superlens; the reflective phase change super lens is used for adjusting the distance between a displayed real image and an eye pupil or the equivalent focal length of a projection system in real time and changing the direction of a light path.

It will be appreciated that the reflective phase-change superlens reduces the size of the projection system along the direction of the optical path by changing the direction of the optical path.

The change of the phase-change material in the crystalline state and the amorphous state is utilized to realize that the focal length of the reflective phase-change super lens is f _min And f _max And (4) adjusting.

In this embodiment, since the reflective phase-change superlens adjusts the propagation path of light, the image generation unit 1 does not need to be restricted by the viewing direction of the eye pupil 5, and the arrangement of the image generation unit 1 of the projection system based on the focusing superlens is more flexible.

As shown in FIG. 8, in one embodiment, the focus superlens based projection system further includes a projection lens 3. The projection lens 3 is disposed downstream of the superlens optical device 2 for focusing on the optical path; for projecting a display real image formed by the image-generating unit 1 via the superlens optics 2 for focusing. The projection lens 3 includes, but is not limited to, a conventional lens or a superlens. Optionally, the projection lens 3 is a chromatic aberration correction superlens for correcting aberration (including chromatic aberration, spherical aberration, coma, and the like).

As shown in FIG. 9, in one embodiment, the focusing superlens based projection system further includes a mirror 6 disposed between the superlens optics 2 for focusing and the projection lens 3 on the optical path.

Wherein the number of the reflecting mirrors 6 can be set according to the requirement. For example, if the position of the image generating unit 1 cannot be modulated by one mirror 6, two or more mirrors 6 may be provided for modulation.

The reflecting mirror 6 may be a conventional reflecting mirror or a super lens having a reflecting function.

In the present embodiment, the reflecting mirror 6 is disposed downstream of the superlens optical device 2 for focusing, and reflects the light modulated by the superlens optical device 2 for focusing, thereby changing the propagation path of the light, so that the design of the projection system based on the superlens for focusing is more flexible.

In one embodiment, the projection lens 3 comprises a refractive lens or a superlens with chromatic correction.

The refractive lens 3 is a conventional lens that can modulate light to direct the light to the eye pupil 5.

The super lens for chromatic aberration correction can correct chromatic aberration at least through phase design, and can reduce or eliminate the chromatic aberration of the projection system, thereby ensuring to improve the imaging quality and improving the visual experience of a user.

In the above embodiments, the superlens includes a substrate and a supersurface structure disposed on a surface of the substrate. Next, the superlens provided by the embodiment of the present application is described in detail with reference to fig. 10 to 17.

As shown in fig. 10, the super-surface structure may be a regular hexagon, and at least one nano-structure is disposed at each vertex and center of the regular hexagon. As shown in fig. 11, the super-surface structure may be a square, and at least one nano-structure is disposed at each vertex and at the center of the square. As shown in fig. 12, the super-surface structure may be a fan shape, and at least one nano-structure is disposed at each vertex and center of the fan shape.

The super-surface structure may comprise an all-dielectric or plasmonic nano-antenna. In the embodiment, the nano structure preferably has an all-dielectric structure, has high transmittance in a visible light band, and can directly adjust and control the characteristics of light such as phase, amplitude, polarization and the like. The nanostructure material includes titanium oxide, silicon nitride, fused silica, aluminum oxide, gallium nitride, hydrogenated amorphous silicon, or the like.

As shown in fig. 13 and 14, the nano-structure may be a polarization-dependent structure such as a nanofin or a nanoelliptic cylinder, which may apply a geometric phase to an incident light; the nano structure can also be a polarization-independent structure such as a nano cylinder and a nano square column, and the structure can apply a propagation phase to incident light.

Air or other filling materials which are transparent in the optical band and have the refractive index difference with the refractive index of the nano structures 7 of more than or equal to 0.5 in absolute value are filled among the nano structures. The absolute value of the refractive index difference is more than or equal to 0.5, so that the requirement-meeting abrupt phase is provided, the stability of the modulated light is ensured, and the influence of the filler on the light is reduced.

According to the embodiments of the present application, as shown in fig. 15 to 17, for the phase-change superlens, in one embodiment, the phase-change superlens adopts a voltage regulation manner. For example, a phase-change superlens is provided with a control voltage, a super surface structure unit of the phase-change superlens adopts a phase-change material, and the phase-change material can greatly change the dielectric constant by changing the crystal lattice in the substance under the action of external excitation (such as heat, laser and external voltage).

GST, which is a commonly used phase change material composed of three elements of germanium (Ge), antimony (Sb) and tellurium (Te), is widely used in rewritable optical disc technology. The solid GST has two phases, a crystalline phase and an amorphous phase, and the two phases have large differences in dielectric constants.

When the temperature of the amorphous GST exceeds the crystallization temperature (at most 160 ℃), the amorphous phase is first transformed into a metastable face-centered cubic crystal structure, similar to NaCl. If the temperature continues to rise, the metastable crystal structure may change to a stable hexagonal structure. The phase transition from the amorphous state to the crystalline state can be achieved by placing GST on a heating plate and heating, using laser pulse irradiation, applying voltage, and the like.

On the other hand, crystalline GST is liquefied by heating it to a temperature exceeding its melting point (at most 640 ℃ C.), and then rapidly cooled to form amorphous GST. The whole cooling solidification process needs to be rapidly completed within 10ns, and if the solidification time is too long, the liquid GST has enough time to be recombined into a crystalline structure. In the case of a laser, the phase change of GST from crystalline to amorphous state often requires a relatively powerful short pulse (pulse width <10ns) laser.

Once the phase change process of the GST crystalline or amorphous state is completed, the GST can maintain the crystalline or amorphous state after the phase change for a long time even if the external stimulus is removed and the environment returns to room temperature. The crystallization ratio of GST can be obtained by controlling physical parameters of the crystallization process, for example, heating amorphous GST, and the crystallization ratio can be adjusted by changing the heating temperature or heating time to obtain different refractive indexes.

Or alternatively, in one embodiment, the phase-change superlens adopts a mechanical regulation mode. For example, the substrate of the super-surface super-lens is made of a stretchable material, such as liquid crystal, the nano-structure of the super-surface super-lens is fixed on the substrate after being processed, and the substrate is stretched or compressed by external mechanical equipment to change the distance between the micro-nano structures on the super-lens, so that the period of light passing through the super-surface super-lens is changed, and the phase of the light is changed.

The nano structure is an all-dielectric structural unit and has high transmittance in a working waveband (such as a visible light waveband). The nanostructures are arranged in regular hexagonal, square, fan-shaped, etc. periodic arrays, for example, the nanostructures may be located at the center and/or vertex of a period.

By focusing the control light at the corresponding nanostructure, the nanostructure can be excited, thereby changing the phase of the supersurface superlens.

A schematic diagram of a phase change cell with one nanostructure of the tunable superlens of the present application is shown in fig. 15 and 16. Here, the phase change cell is a transmissive phase change cell, wherein the phase change cell, i.e., the nanostructure, has a substrate 70. Conduction and heating can be achieved directly with the phase change element. As shown in fig. 15, the first electrode 101 is electrically connected to the lower side of the nanostructure 201, and the second electrode 102 is electrically connected to the upper side of the nanostructure 201. Under the action of the two electrodes, the nano structure 201 made of the phase change material directly conducts electricity and generates heat, and the change of the phase change state is realized. Here, the materials of the first electrode and the second electrode are transparent in the operating band to avoid reducing the transmittance of light.

Here, the second electrode 102 may be directly electrically connected to the nanostructure 201; alternatively, as shown in fig. 15, the phase change cell further includes: connecting layer 103, and connecting layer 103 is transparent in the operating band. The connection layer 103 is located on one side of the nano structure 201 far away from the first electrode 101, and is electrically connected with the nano structure 201; the second electrode 102 is located between the first electrode 101 and the connection layer 103, and is electrically connected to the connection layer 103. In the embodiment of the present invention, the layered first electrode 101 and the connecting layer 103 are made of conductive and transparent materials, for example, ITO can be used.

For example, in order to avoid the leakage between the first electrode 101 and the second electrode 102 disposed at an interval, referring to fig. 15, the phase change cell further includes: a first insulating layer 502; the first insulating layer 502 is located between the first electrode 101 and the second electrode 102, and abuts against the first electrode 101 and the second electrode 102. Optionally, the phase change cell may further include a second insulating layer 504 juxtaposed with the nanostructure 201, and in the case of being able to support part of the electrodes, insulation may also be achieved. As shown in fig. 8, the second insulating layer 504 may function to support the connection layer 103.

Referring to fig. 16, the phase change cell may also include: a filler 60, the filler 60 being transparent at the operating band; the filler 60 is filled between the nanostructures 201. In the embodiment of the present invention, a transparent material, i.e. the filler 60, is filled around the nano-structure 201; the filler 60 has a high transmittance in the operating band. Preferably, the absolute value of the difference between the refractive index of the filler and the refractive index of the nanostructures is greater than or equal to 0.5.

An alternative reflective phase change cell provided by an embodiment of the present application is shown in fig. 17. Referring to fig. 7, the intermediate member of the phase change cell includes a first metal reflective layer 301. The phase change element 20 is positioned on the light reflecting side of the first metal reflecting layer 301; the first electrode 101 and the second electrode 102 are electrically connected to the first metal reflective layer 301, respectively, and are located at two sides of the phase change element 20.

In the embodiment of the present invention, the first metal reflective layer 301 has a reflective side capable of reflecting light, and the phase change element 20 is located on the reflective side, so as to modulate the reflective light. For convenience of description, in this embodiment, the phase change element 20 includes one nanostructure 201, or the phase change element 20 may also include a plurality of nanostructures 201, and the plurality of nanostructures 201 are arranged periodically, and fig. 17 illustrates the phase change element 20 by using the nanostructure 201 as an example. The first electrode 101 and the second electrode 102 electrically connected to the first metal reflective layer 301 are respectively located at two sides of the phase change element 20, so that after the first metal reflective layer 301 is energized, the portion closest to the nanostructure 201 can generate heat, thereby effectively heating the nanostructure 201.

Alternatively, the nanostructures 201 may be disposed directly on the first metallic reflective layer 301, i.e., abutting. Alternatively, referring to fig. 17, the phase change cell further includes: a first dielectric layer 401; the first dielectric layer 401 is located between the first metallic reflective layer 301 and the phase change element 20 and abuts the first metallic reflective layer 301 and the phase change element 20. The first dielectric layer 401 abuts against the nanostructure 201, and a difference between the refractive index of the first dielectric layer 401 and the refractive index of the nanostructure 201 (or the equivalent refractive index of the nanostructure 201) is smaller than or equal to a preset threshold, for example, the preset threshold is 1 or 0.5, so that the refractive index of the nanostructure 201 is matched with the refractive index of the first dielectric layer 401, and the transmittance of the nanostructure 201 can be improved. For example, the thickness of the metal reflective layer (e.g., the first metal reflective layer 301) may be 100nm to 100 μm, and the thickness of the first dielectric layer 401 may be 30nm to 1000 nm.

The first dielectric layer 401 is transparent in the operating band, and can transmit visible light, infrared light, and the like. For example, the material of the first dielectric layer 401 may be quartz glass; alternatively, the material of the first dielectric layer 401 may be a material capable of conducting electricity and being transparent, such as Indium Tin Oxide (ITO); in this case, the first dielectric layer 401 may be connected to two electrodes, i.e., the first dielectric layer 401 may be electrically heated.

In the embodiment of the present invention, if the initial position of the nano-structure 201The initial state is amorphous, and after the light ray a enters the reflective phase change unit, the nano structure 201 can perform phase modulation on the light ray a and make the light ray a

Back reflection and emergence; if the electrode applies voltage excitation to the first metal reflective layer 301, the first metal reflective layer 301 is turned on to heat and conduct heat to the nanostructure 201, so that the phase change material undergoes phase change from an amorphous state to a crystalline state, and at this time, after the incident light ray a is modulated by the nanostructure 201, the phase of the incident light ray a is changed into a phase variable

Thereby achieving different modulation effects. It can be understood by those skilled in the art that the above description only illustrates the working principle of one phase change cell, and the working principle of the superlens including a plurality of phase change cells is similar, and is not repeated herein.

It is understood that, when the phase change material provided in the above embodiments is used to make the filler 60, the change of the refractive index of the filler can be realized by exciting and switching the phase change material, so that the focal length of the entire superlens changes synchronously with the change of the phase change material.

According to an embodiment of the present application, referring to fig. 18, a superlens optical device for focusing includes at least one phase-change superlens, wherein a phase-change element of the phase-change superlens includes a substrate 70, a nanostructure 201, a first electrode layer 101, a filler 60, a second electrode layer 102; the nano structure array is arranged on one side of the substrate; the filler is made of a phase-change material; the first electrode layer and the filler are sequentially filled among the nano structures in a layered mode along the direction far away from the substrate; and the sum of the heights of the first electrode layer and the filler is greater than or equal to the height of the nano structure; the second electrode layer is arranged on one side of the filler far away from the first electrode layer.

Embodiments of the present application also provide an apparatus having a focusing superlens based projection system provided in the above embodiments.

The projection system based on the focusing super lens and the equipment with the projection system adjust the distance between the displayed real image and the eye pupil or the equivalent focal length of the projection system in real time through the super lens optical device for focusing, so that focusing conflict is reduced or eliminated. And compared with the traditional projection system, the complexity of the projection system in VR/AR equipment is reduced due to the introduction of the super lens, the miniaturization and the light weight are realized, the response time is shortened, and the wearing comfort level is improved.

The above embodiments are only specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention, and all should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A focusing superlens based projection system, comprising:

an image generation unit;

a superlens optical device for focusing, disposed downstream of the image generation unit on an optical path;

under the working condition of the projection system, the superlens optical device for focusing can adjust the distance between a displayed real image and an eye pupil or the equivalent focal length of the projection system in real time.

2. The focusing superlens-based projection system of claim 1, wherein the superlens optics for focusing is a MEMS micro-motion based superlens group, wherein the MEMS micro-motion based superlens group comprises: at least two superlenses; at least one micro-electromechanical actuator for moving at least one superlens of the superlens group; wherein at least one superlens is movable by the at least one microelectromechanical actuator in the direction of the light propagation path such that the focal length of the superlens group changes.

3. The focusing superlens-based projection system of claim 2, wherein the MEMS micro-motion based superlens group further comprises: a MEMS flexible suspension coupled with at least one of the at least two superlenses;

4. The focusing superlens-based projection system of claim 2, wherein each of the at least two superlenses comprises a first electrically conductive layer, an electrical actuation layer, and nanostructures, wherein the electrical actuation layer is disposed on one side of the first electrically conductive layer; the nanostructure is arranged on one side of the electric actuating layer far away from the first conducting layer;

5. The focusing superlens-based projection system of claim 1, wherein the superlens optics for focusing comprise at least one phase-changing superlens, wherein the phase-changing superlens comprises a plurality of phase-changing elements arranged in an array and a plurality of actuated elements arranged in an array;

wherein the phase change element comprises at least one nanostructure made of a phase change material; the exciting element comprises a first electrode and a second electrode which are arranged at intervals; the first electrode and the second electrode are electrically connected through an intermediate piece;

6. The focusing superlens-based projection system of claim 5, wherein the middleware further comprises: a first metal reflective layer;

7. The focusing superlens-based projection system of claim 1, wherein the superlens optics for focusing comprise at least one phase-change superlens, wherein the phase-change element comprises a substrate, nanostructures, a first electrode layer, a filler, a second electrode layer;

the nanostructure array is arranged on one side of the substrate;

the filler is made of a phase change material;

the second electrode layer is arranged on one side, far away from the first electrode layer, of the filler.

8. A focusing superlens-based projection system according to any of claims 5 to 7, wherein the phase-change superlens is a reflective phase-change superlens; the reflective phase change super lens is used for adjusting the distance between the displayed real image and the eye pupil or the equivalent focal length of the projection system in real time and changing the direction of a light path.

9. The focusing superlens-based projection system of any one of claims 5-7, wherein the phase-change superlens is a transmissive phase-change superlens for adjusting a distance between the displayed real image and the eye pupil or an equivalent focal length of the projection system in real time.

10. The focusing superlens-based projection system of claim 1, further comprising a projection lens disposed downstream of the superlens optical means for focusing on an optical path for projecting the displayed real image formed by the image-generating unit via the superlens optical means for focusing.

11. The focusing superlens-based projection system of claim 10, further comprising a mirror disposed in the optical path between the superlens optics for focusing and the projection lens.

12. The focusing superlens-based projection system of claim 10, wherein the projection lens comprises a refractive lens or a superlens with chromatic correction.

13. The focusing superlens-based projection system of claim 1 or 10, wherein the image generation unit comprises a micro-led display array and a rotating disk filter;

the micro light-emitting diode display array is used for generating light with at least one color;

14. The focusing superlens-based projection system of claim 1 or 10, wherein the image generation unit comprises at least two discrete lasers, at least two dichroic mirrors, a prism and a digital micromirror device, arranged in sequence along the optical path;

the at least two dichroic mirrors are used for carrying out frequency selection and optical path turning on laser light generated by the at least two separated lasers;

the digital micromirror device is used for modulating the light reflected by the prism according to the projected image.

15. The focusing superlens-based projection system of claim 1 or 10, wherein the image generation unit comprises two blue lasers, a fluorescent disc, at least two dichroic mirrors, a prism, and a digital micromirror device;

one of the two blue lasers is used for generating blue laser light, and the other of the two blue lasers is used for irradiating a fluorescent disc to generate at least two laser lights with different wavelengths from the blue laser light;

the at least two dichroic mirrors are used for carrying out frequency selection and light path turning on the blue laser and the at least two lasers;

16. The focusing superlens-based projection system of claim 1 or 10, wherein the image generation unit comprises at least two discrete narrow-band light emitting diodes, at least two dichroic mirrors, a prism and a digital micromirror device, arranged in sequence along the optical path;

17. An apparatus comprising a focusing superlens based projection system as claimed in any one of claims 1 to 16.