CN114967154A - Preparation device and method of holographic optical element light combiner for displaying eye pupil box expansion in near-to-eye mode - Google Patents

Abstract

The invention discloses a preparation device and a preparation method of a holographic optical element light combiner for displaying eye pupil box expansion near an eye. The preparation device of the holographic optical element light combiner comprises a coherent light source, a beam expanding and collimating system, a beam splitter, a scanning signal light module, a holographic dry plate, a first lens, a first reflector, a mobile platform driving system, a master controller, an electronic shutter, an attenuator and the like. The invention also provides a holographic optical element light combiner which is prepared by adding the micro-lens array into the light path and is used for displaying the expansion of the eye pupil box near the eye. The invention adopts the scanning signal light module to scan the signal light to prepare the holographic optical element light combiner for near-eye display eye pupil box expansion. The number and the corresponding positions of exposed focuses are determined according to the requirement of the pupil box expansion, the motion track and the exposure time of the space moving platform are determined, and the scanning signal optical module circularly scans and forms a plurality of convergence focuses at the positions of human eyes after the holographic dry plate is exposed, so that the near-eye display pupil box is effectively expanded.

Description

Preparation device and method of holographic optical element light combiner for displaying eye pupil box expansion in near-to-eye mode

Technical Field

The invention relates to the technical field of near-eye display, in particular to a device and a method for preparing a holographic optical element light combiner for near-eye display of eye pupil box expansion.

Background

The near-eye display is a Virtual Reality (VR) and Augmented Reality (AR) implementation platform, has a very optimistic development prospect, and is expected to revolutionize the fields of medical care, communication, entertainment, education, manufacturing and the like. An ideal near-eye display must be able to provide high resolution images over a large field of view while supporting monocular depth adjustment, compact appearance, and a relatively large eye pupil box.

The holographic display technology is a display method of recording a specific wave surface emitted from an object in the form of interference fringes by using the principles of light interference and diffraction, and reproducing the recorded wave surface under a certain condition to form an original three-dimensional image of the object. The holographic recording method reserves all amplitude and phase information of object light waves, and people can obtain the same visual effect when observing the holographic three-dimensional image as the original object. The holographic method is applied to near-eye display, so that the problem of convergence conflict can be fundamentally solved, and monocular depth adjustment is realized.

A Holographic Optical Element (HOE) is a diffraction-based optical element that can be prepared by analog holographic exposure or digital holographic printing with a certain wavelength selectivity. Since the HOE can be recorded on a thin sheet of holographic material, it is often used as a light combiner for an AR near-eye display to achieve a compact profile. The holographic near-eye display system is limited by the space bandwidth product of the system in principle, the field angle and the size of the pupil box are mutually restricted, and generally, under the condition of realizing a large field angle, the size of the pupil box is too small, so that the holographic near-eye display system is not beneficial to being worn and watched by a user. How to expand the pupil box of the holographic near-eye display under the premise of ensuring a certain field angle is a new challenge.

Disclosure of Invention

In order to solve the problems in the prior art, the invention aims to overcome the defects in the prior art and provide a device and a method for preparing a holographic optical element combiner for displaying the expansion of an eye pupil box near an eye.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

a preparation device of a holographic optical element light combiner for near-eye display eye pupil box expansion comprises a coherent light source, a beam expanding and collimating system, a beam splitter, a scanning signal light module, a holographic dry plate, a first lens, a first reflector, a mobile platform driving system, a master controller, an electronic shutter and an attenuator; constitute the preparation facilities that holographic optical element closes the optical ware based on near-to-eye display eye pupil case of scanning signal optical module expands, wherein:

the coherent light source is used for generating laser with pure quality and stable spectrum;

the beam expanding and collimating system is positioned behind the output end of the coherent light source and is used for collimating, expanding and filtering coherent light output by the coherent light source to obtain parallel light of a wide light beam;

the beam splitter is a block beam splitter prism or a flat plate beam splitter and divides parallel light passing through the beam expanding and collimating system into reference light and signal light;

the scanning signal light module is used for realizing the scanning of an optical convergence focus behind the holographic dry plate and is connected with a driving system of the mobile platform;

the holographic dry plate is a holographic recording material and is used for recording the amplitude and the phase of light;

the first lens is a single lens, a double-cemented lens or a lens group consisting of a plurality of lenses and is used for converging parallel light to be used as a reference beam;

the first reflector is a plane reflector and is used for changing the direction of an optical path so that divergent light is obliquely incident and irradiates on the holographic dry plate;

the moving platform driving system consists of a third motor and a motor driver together, is used for controlling the motion of the space moving platform, and is connected with the scanning signal optical module and the master controller;

the master controller is used for controlling the operation of the motor and the working state of the electronic shutter and is connected with the mobile platform driving system and the electronic shutter;

the electronic shutter controls the on-off of the light path by combining the working state of the scanning signal optical module and is connected with the master controller;

the attenuator is used for controlling the power of the laser in the optical path.

Preferably, the scanning signal optical module includes: the space moving platform, the second reflector and the fourth lens; the second reflector and the fourth lens are fixed on the space moving platform, and the fourth lens is arranged behind the second reflector.

Preferably, the scanning signal optical module is arranged behind the beam splitter, connected with the mobile platform driving system, and driven by the mobile platform driving system to perform two-dimensional scanning.

Preferably, the scanning signal light module comprises a third reflector, a fourth reflector, a fifth reflector, a sixth reflector, a seventh reflector, a fifth lens, a first support, a second support, a first motor and a second motor; the third reflector, the fourth reflector, the fifth reflector, the sixth reflector and the seventh reflector are all plane reflectors, and light split by the beam splitter sequentially passes through the third reflector, the fourth reflector, the fifth reflector, the sixth reflector and the seventh reflector for reflection and then passes through the fifth lens to form a convergent light beam; wherein: the fourth reflector and the fifth reflector are fixed on the second support; the sixth reflector, the seventh reflector and the fifth lens are fixed on the first support; the first motor and the second motor are stepping motors or servo motors and are respectively used for controlling the position and the height of the first support to drive the convergent light beam to synchronously perform two-dimensional scanning.

The utility model provides a preparation facilities of holographic optical element closes optical organ of near-eye display eye pupil case extension, includes coherent light source, expands beam collimation system, beam splitter, holographic dry plate, first lens, second mirror, electronic shutter, attenuator, eighth mirror, lens array, relay optical system, constitutes the preparation facilities of holographic optical element closes optical organ based on near-eye display eye pupil case extension of lens array, wherein:

the coherent light source is used for generating laser with pure quality and stable spectrum;

the beam expanding and collimating system is positioned behind the output end of the coherent light source and is used for collimating, expanding and filtering coherent light output by the coherent light source to obtain parallel light of a wide light beam;

the beam splitter is a block beam splitter prism or a flat plate beam splitter and divides parallel light passing through the beam expanding and collimating system into reference light and signal light;

the holographic dry plate is a holographic recording material and is used for recording the amplitude and the phase of light;

the first lens is a single lens, a double-cemented lens or a lens group consisting of a plurality of lenses and is used for converging parallel light to be used as a reference beam;

the first reflector is a plane reflector and is used for changing the direction of an optical path so that divergent light is obliquely incident and irradiates the holographic dry plate;

the electronic shutter controls the on-off of the light path by combining the working state of the scanning signal optical module;

the attenuator is used for controlling the power of the laser in the light path;

the eighth reflector is a plane reflector and is used for changing the direction of an optical path so that parallel light passes through the lens array;

the lens array is an array structure consisting of a plurality of lenses and is used for spatially dividing a complete laser wavefront into a plurality of tiny parts, and each part is focused on a focal plane by the corresponding small lens so as to obtain a plane consisting of a series of focal points;

the relay optical system is used for imaging the focus array formed by the lens array to the other side of the holographic dry plate.

Preferably, the relay optical system is composed of a first relay lens and a second relay lens; the back focal plane position of the lens array and the focal plane position required by the light combiner form a conjugate relation.

The invention discloses a preparation method of a holographic optical element combiner for near-eye display eye pupil box expansion, which adopts a preparation device of the holographic optical element combiner for near-eye display eye pupil box expansion based on a scanning signal optical module, and comprises the following steps:

the first step is as follows: the running speed of the space moving platform can be set by matching with a speed reducer according to the rated rotating speed of the motor, the position of a focus required to pass through in the moving process of the space moving platform is determined, and the initial position of the space moving platform is adjusted;

the second step is that: initializing a world coordinate system, planning a running path according to the position of the focus array, and calculating the exposure time T required by each focus position according to system parameters such as exposure light intensity, a holographic dry plate, the focus number of the focus array, single-point exposure times and the like _i (i is the focal position of the ith exposure);

the third step: the space moving platform moves according to the planned path until the first focus position needing exposure is reached, the space moving platform is braked and kept static for t time, and the master controller receives brake feedback of the space moving platform and judges whether the space moving platform is stable or not within the t time;

the fourth step: judging whether the space moving platform is stable, immediately opening the electronic shutter to switch on the light path after the period of time T is over, and keeping the electronic shutter open for a period of time T according to the calculated exposure time _i ；

The fifth step: circularly executing the third step and the fourth step to circularly expose each focus position for multiple times, and ensuring that the diffraction efficiency of each focus position is relatively uniform;

and a sixth step: and stopping exposure, ending scanning, and performing bleaching post-treatment on the holographic dry plate to obtain the holographic optical element combiner for expanding the eye pupil box for near-eye display.

Preferably, in the second step, in order to ensure that the light combiner has better diffraction efficiency as a whole and ensure that the diffraction efficiency of each focus position is relatively uniform, exposure is repeated for each focus position for multiple times.

The invention discloses a preparation method of a holographic optical element combiner for near-eye display eye pupil box expansion, which adopts a preparation device of the holographic optical element combiner for near-eye display eye pupil box expansion based on a micro-lens array, and comprises the following steps:

the first step is as follows: calculating exposure time t and exposure intensity I required for preparing a holographic optical element combiner with expanded eye pupil according to system parameters such as a holographic dry plate;

the second step is that: adjusting the attenuator until the beam intensities of the reference light and the signal light irradiated on the holographic dry plate satisfy the calculated exposure intensity I;

the third step: opening the electronic shutter to switch on the light path according to the exposure time t calculated in the first step and keeping opening for the time t;

the fourth step: and closing the electronic shutter to finish exposure and carrying out bleaching post-treatment on the holographic dry plate to obtain the holographic optical element light combiner for expanding the eye pupil box for near-eye display.

Compared with the prior art, the invention has the following advantages:

the invention adopts a scanning signal light module to scan signal light to prepare a holographic optical element light combiner for near-eye display eye pupil box expansion; the number and the corresponding positions of exposed focuses are determined according to the requirement of the pupil box expansion, the motion track and the exposure time of the space moving platform are determined, and the scanning signal optical module circularly scans and forms a plurality of convergence focuses at the positions of human eyes after the holographic dry plate is exposed, so that the near-eye display pupil box is effectively expanded.

Drawings

Fig. 1 is a schematic structural diagram of a preparation apparatus of a holographic optical element combiner for near-eye display of eye pupil box expansion based on a scanning signal optical module according to embodiment 1 of the present invention.

Fig. 2 is a schematic structural diagram of a scanning signal optical module of a preparation apparatus of a holographic optical element combiner for near-eye display of eye pupil box expansion, provided in embodiment 1 of the present invention.

Fig. 3 is a schematic structural diagram of a device for preparing a holographic optical element combiner for displaying pupil box expansion in near-eye based on a microlens array according to embodiment 2 of the present invention.

Fig. 4 is a schematic structural diagram of a conjugate preparation apparatus of a holographic optical element combiner for near-eye display of eye pupil box expansion, provided in embodiment 3 of the present invention, based on a scanning signal optical module.

Fig. 5 is a schematic structural diagram of a conjugate preparation apparatus of a holographic optical element combiner for near-eye display of pupil box expansion based on a microlens array according to embodiment 4 of the present invention.

Fig. 6 is a flowchart of a method for manufacturing a holographic optical element combiner for near-eye display eye pupil box expansion according to embodiments 1 and 3 of the present invention.

Fig. 7 is a timing chart of the operation of the method for manufacturing the holographic optical element combiner for near-eye display eye pupil box expansion based on the scanning signal optical module in embodiments 1 and 3 of the present invention.

Fig. 8 is a flowchart of a method for manufacturing a holographic optical element combiner for near-eye display eye pupil box expansion based on a microlens array according to embodiments 2 and 4 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in detail below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

The above-described embodiments are further illustrated below with reference to specific examples, in which preferred embodiments of the invention are detailed below:

example 1

An embodiment of the apparatus for manufacturing a holographic optical element combiner for displaying eye pupil box expansion near to eye according to the present invention is shown in fig. 1, and includes a coherent light source 100, a beam expanding and collimating system 110, a beam splitter 120, a scanning signal light module 130, a holographic dry plate 140, a first lens 150, a first mirror 160, a moving platform driving system 170, a total controller 180, an electronic shutter 190, and an attenuator 200.

The coherent light source 100 is generally a laser in the visible light band, and is used for generating coherent light with pure quality and stable spectrum. The laser may be a semiconductor laser, a gas laser or a solid state laser. The wavelength of the laser should be matched with the actual requirement, if the color holography is realized, the lasers with different wavelengths corresponding to RGB should be selected for use.

The beam expanding and collimating system 110 is located behind the output end of the coherent light source 100, and is configured to perform collimating, beam expanding and filtering on the coherent light output by the coherent light source 100 to obtain parallel light of a wide light beam. The beam expanding and collimating system 110 is generally composed of a second lens 111, a pinhole filter 112 and a third lens 113. Generally, coherent light generated by the coherent light source 100 is converged to the pinhole filter 112 through the second lens 111 to filter out stray light, so as to generate a spherical wave close to an ideal spherical wave, and then collimated through the third lens 113 to generate a wide beam of parallel light. The second lens 111 may be a single lens, a double cemented lens or a combination of multiple lenses. In practical system applications, microscope objectives or similar commercially available objectives are often used. The pinhole filter 112 is generally used to filter stray light in the beam emitted from the coherent light source to improve the beam quality. The third lens 113 may be a single lens, a double cemented lens or a collimating lens group composed of a plurality of lenses.

The beam splitter 120 is a block beam splitter prism or a flat plate beam splitter, and splits an incident beam into two beams, and the ratio of reflected light energy to transmitted light energy can be controlled by changing coating parameters. The beam-expanding collimating system 110 collimates the parallel light into two beams, the beam reflected by the beam splitter 120 is the reference light, and the beam transmitted by the beam splitter 120 is the signal light. The beam splitter 120 needs to select an appropriate splitting ratio according to the system requirements. The beam splitter 120 may also be a polarization beam splitter, which may be combined with a polarizer and a half-wave plate to construct any light intensity matching device. The beam splitter 120 may be disposed before the beam expanding and collimating system 110, or may be disposed after the beam expanding and collimating system 110, and the specific disposition position needs to be determined according to actual requirements. In practical operation, according to a specific optical path, the light beam reflected by the beam splitter 120 may be selected as the signal light, and the light beam transmitted by the beam splitter 120 may be selected as the reference light.

The reference light is converged by the first lens 150 to form a spherical wave emitted from the point light source, and then reflected off-axis by the first reflector 160 to irradiate the holographic plate 140. Here, the distance from the back focus of the first lens 150 to the holographic dry plate 140 and the corresponding off-axis angle are determined by design requirements in near-eye display. The first mirror 160 is used to adjust the off-axis angle of illumination to the holographic plate 140. Generally, for wearing convenience and avoiding collision between the head and the light, the off-axis angle is generally over 40 degrees.

The first lens 150 is a single lens, or a double-cemented lens, or a lens group composed of a plurality of lenses, and is disposed in the subsequent optical path of the beam splitter 120 for converging the parallel light as the reference beam. The first reflecting mirror 160 is a plane reflecting mirror for changing the direction of the light path so that the diverging light is obliquely incident to the holographic plate 140. The first lens 150 and the first reflector 160 may be replaced by a single curved reflector, which can achieve the functions of changing the propagation direction of light and converging parallel light beams. The curved mirror is a reflection imaging, so that chromatic aberration does not occur, and the manufacture of a large-aperture lens is extremely difficult, and the curved mirror manufactured by using the reflection principle is easy to manufacture. The curved surface reflector can be a convex surface reflector or a concave surface reflector.

The signal light passes through the scanning signal light module 130 to realize the scanning of the optical convergence focus behind the holographic plate. The scanning signal optical module 130 is disposed in front of the movable stage driving system 170, and is connected to the movable stage driving system 170 behind the beam splitter 120. The scanning signal optical module 130 is composed of a space moving platform 131, a second mirror 132 and a fourth lens 133. The second reflecting mirror 132 and the fourth lens 133 are disposed on the space moving platform 131, and the fourth lens 133 is disposed behind the second reflecting mirror 132. The signal light is reflected by the second reflecting mirror 132, and then forms a converged spherical wave by the fourth lens 133, and is irradiated from the other side of the holographic plate 140. When the space moving platform 131 moves in the horizontal direction, the focus formed by the signal light is scanned in the horizontal direction. In the actual manufacturing process, motion control is required according to the designed focal position. Since fig. 1 is a top view, only the left and right movement of the moving platform can be shown, but actually the moving platform can move up and down simultaneously to meet the requirement of focus two-dimensional scanning exposure.

In order to more fully utilize the beam energy of the signal light, a preferred structure 9000 of the scanning signal light module 130 is shown in fig. 2. The scanning signal light module 9000 is preferably placed behind the beam splitter 120 to perform multi-focus scanning using the beam energy of the signal light sufficiently to perform interference recording with the reference light on the holographic plate 140. The scanning signal optical module optimized structure 9000 is composed of a third reflector 9001, a fourth reflector 9002, a fifth reflector 9003, a sixth reflector 9004, a seventh reflector 9005, a fifth lens 9006, a first support 9007, a second support 9008, a first motor 9009 and a second motor 9010. The third reflecting mirror 9001 is a plane reflecting mirror, and is disposed behind the beam splitter 120 to deflect the light transmitted from the beam splitter 120 by 90 degrees in a horizontal plane so that the signal light propagates in the positive direction of the Y axis. The fourth reflecting mirror 9002 is a plane reflecting mirror, and is disposed behind the third reflecting mirror 9001, and the surface thereof is rotated counterclockwise by 45 degrees around the X axis in the XZ plane, so that the signal light propagates in the negative direction of the Z axis. The fifth reflecting mirror 9003 is a plane reflecting mirror, is disposed below the fourth reflecting mirror 9002, and is rotated counterclockwise by 45 degrees about the Y axis in the YZ plane to transmit the signal light in the negative X-axis direction. The sixth reflecting mirror 9004 is a plane reflecting mirror, and is placed after the fifth reflecting mirror 9003, and is placed by rotating 45 degrees counterclockwise around the Y axis in the XY plane so that the signal light propagates toward the positive direction of the Z axis. The seventh mirror 9005 is a plane mirror, and is disposed above the sixth mirror 9004, and is disposed to rotate clockwise by 45 degrees about the X axis in the XZ plane so that the signal light travels in the positive direction of the Y axis. The fifth lens 9006 is a single lens, a doublet lens or a lens group consisting of a plurality of lenses. The fifth lens 9006 is disposed behind the seventh mirror 9005, and forms the signal light into a converged spherical wave. The first support 9007 and the second support 9008 are height-adjustable sliding supports and are used for adjusting the light emitting direction, the position and the height of the second support 9008 are manually adjusted, and the first support 9007 is connected with a first motor 9009 and a second motor 9010. The fourth and fifth reflecting mirrors 9002 and 9003 are fixed to a second support 9008. The sixth mirror 9004, the seventh mirror 9005 and the fifth lens 9006 are fixed to a first holder 9007. The first motor 9009 and the second motor 9010 are generally stepping motors or servo motors, and are respectively used for controlling the position and the height of the first support 9007. The rotating directions are all observed from the positive direction of the coordinate axis. The fifth lens 9006 and the seventh mirror 9005 should perform two-dimensional scanning motions in synchronization with the motion state of the first support 9007. The sixth reflecting mirror 9004 is driven by a first motor 9009 to move in the X-axis direction. The first and second supports 9007, 9008 may be mechanical structures with similar functions. The first motor 9009 and the second motor 9010 are matched with each other by adopting an adaptive motor driver. The combination of the seventh mirror 9005 and the fifth lens 9006 may be replaced with an optical element such as a curved mirror to achieve a similar function.

The position of the spatial movable platform 131 is determined by the movable platform driving system 170. The driving system 170 of the mobile platform is composed of a third motor 171 and a motor driver 172, and is connected with a master controller 180, and the connection mode of the driving system and the master controller can be USB, serial port, general I/O, and the like, and is used for controlling the spatial position of the scanning signal optical module 130, and the transmission mode between the third motor 171 and the spatial mobile platform 131 can be belt transmission, gear transmission, rack and pinion transmission, worm and gear transmission, or the combination transmission of multiple transmission modes. The combination of the second mirror 132 and the fourth lens 133 may be replaced by a curved mirror to achieve a similar function. The fourth lens 133 may be a single lens, a double cemented lens or a lens group composed of a plurality of lenses. The third motor 171 is generally a stepping motor or a servo motor. The motor driver 172 should match the selected motor.

The holographic dry plate 140 is a holographic recording material. Commonly used holographic recording media are silver halide emulsions, dichromated gelatin, photoresists, photopolymers, photoconductive thermoplastics, and the like. The photopolymer holographic recording material has the advantages of high sensitivity and diffraction efficiency, convenient processing, real-time dry development and the like. The moving platform driving system 170 is composed of a third motor 171 and a motor driver 172, and is used for controlling the movement of the space moving platform 131. The third motor 171 is connected to the space moving platform 131, and the motor driver 172 is connected to the overall controller 180. The general controller 180 is a computer for controlling the operation of the motor and the operation of the electronic shutter 190. Which is connected to motor driver 172 and electronic shutter 190.

The electronic shutter 190 is an electromagnetic shutter, or an electrically controlled mechanical shutter, or a mechano-electronic system with similar functions, and is connected to the main controller 180 for controlling the on/off of the optical path. The overall controller 180 controls the operation of the electronic shutter 190 in conjunction with the operation of the space moving platform 131. When the spatial mobile platform 131 moves, the master controller 180 controls the electronic shutter 190 to block the light path; when the space moving stage 131 stops, the overall controller 180 controls the electronic shutter 190 to open the optical path. The attenuator 200 is a device for attenuating the light intensity, and is used to control the beam intensity of the signal light and the reference light for exposing the holographic plate. The attenuator 200 may be an absorption-type laser power attenuator, a dielectric reflection-type laser power attenuator, or a modulation-type laser power attenuator.

The light combiner for expanding the near-eye display eye pupil box can be prepared by the embodiment. In the specific preparation process, the running speed of the space moving platform is set through the master controller, the number and the positions of focal points needing exposure in the moving process of the space moving platform are determined during preparation, and the initial position of the space moving platform is adjusted. Then initializing a world coordinate system, planning a running path and calculating the exposure time T required by each focus position _i . When the space moving platform moves according to the planned path until the first focal position to be exposed is reached, the space moving platform is braked and kept stationary for t time, and the master controller 180 receives brake feedback of the space moving platform and judges whether the preparation device is stable or not within t time. When the system judges that the preparation apparatus has been stationary and immediately opens the electronic shutter 190 to turn on the optical path after waiting for T for the end of the period of time and keeps the electronic shutter 190 open for a period of time T according to the calculated exposure time _i (ii) a The above steps are performed in a loop until all focus positions are exposed. In the actual operation process, theAnd each focus position is exposed for multiple times in a circulating manner, so that the diffraction efficiency of each focus position is relatively uniform. And finally obtaining the holographic optical element light combiner for the expansion of the eye pupil box for near-eye display.

Example 2

An embodiment of the apparatus for preparing a holographic optical element combiner for near-eye display of pupil box expansion according to the present invention is shown in fig. 3, and includes a coherent light source 100, a beam expanding and collimating system 110, a beam splitter 120, a holographic dry plate 140, a first lens 150, a first mirror 160, an electronic shutter 190, an attenuator 200, an eighth mirror 210, a lens array 220, and a relay optical system 230.

The coherent light source 100 is a laser in the visible light band, and is used for generating coherent light with pure quality and stable spectrum. The beam expanding and collimating system 110 is located behind the output end of the coherent light source 100, and is configured to perform collimating, beam expanding and filtering on the coherent light output by the coherent light source 100 to obtain parallel light of a wide light beam. The beam splitter 120 is a block-shaped beam splitter prism or a flat plate beam splitter, and divides parallel light collimated by the beam expanding and collimating system 110 into two beams, a light beam reflected by the beam splitter 120 is reference light, and a light beam transmitted by the beam splitter 120 is signal light. In practical operation, according to a specific optical path, the light beam reflected by the beam splitter 120 may be selected as the signal light, and the light beam transmitted by the beam splitter 120 may be selected as the reference light. The beam splitter 120 may be disposed before the beam expanding and collimating system 110, or may be disposed after the beam expanding and collimating system 110, and the specific disposition position needs to be determined according to actual requirements.

The reference light is converged by the first lens 150 to form a spherical wave emitted from the point light source, and then reflected off-axis by the first reflector 160 to irradiate the holographic plate 140. Here, the distance from the back focus of the first lens 150 to the holographic dry plate 140 and the corresponding off-axis angle are determined by design requirements in near-eye display. Generally, for wearing convenience and avoiding collision between the head and the light, the off-axis angle is generally over 40 degrees. The signal light is irradiated onto the holographic plate 140 from the other side through the eighth mirror 210, the lens array 220, and the relay optical system 230.

The first lens 150 is a single lens, a double cemented lens, or a lens group composed of a plurality of lenses, and is disposed in the subsequent optical path of the beam splitter 120 for converging the parallel light as a reference beam. The first reflecting mirror 160 is a plane reflecting mirror for changing the direction of the light path so that the parallel light is obliquely incident to the holographic plate 140 to provide divergent light thereto. The holographic dry plate 140 is a holographic recording material. Commonly used holographic recording media are silver halide emulsions, dichromated gelatin, photoresists, photopolymers, photoconductive thermoplastics, and the like.

The electronic shutter 190 is an electromagnetic shutter, or an electrically controlled mechanical shutter, or a mechano-electronic system with similar functions, and is connected to the main controller 180 for controlling the on/off of the optical path. The attenuator 200 is a laser power attenuator, and is used for controlling the power of the laser in the optical path. The eighth reflecting mirror 210 is a plane reflecting mirror, and is used for changing the direction of the light path, so that the parallel light is irradiated onto the lens array 220.

The lens array 220 is an array of a plurality of lenses, and is composed of a plurality of lenses arranged in a certain way, and is used for dividing a complete laser wavefront into a plurality of tiny parts in space, each part is focused on a focal plane by a corresponding small lens, and a plane composed of a series of focal points can be obtained by a series of lenses. Common arrangement modes of the lens array include single row type, M × N arrangement, full cloth type and the like; the shapes of the lens cells commonly found in lens arrays are hexagonal, square and circular. The specific arrangement and shape of the lens unit need to be selected according to the system requirements. The eighth mirror 210 and the lens array 220 can be replaced by a single curved mirror array, and the functions of changing the propagation direction of light and forming a focal array can be simultaneously realized.

The relay optical system 230 may be a 4f optical system, and is composed of a first relay lens 231 and a second relay lens 232. The back focal plane position of the lens array 220 is in conjugate relation with the focal plane position required by the light combiner, so that the energy is fully utilized. The magnification of the 4f optical system is determined by the focal length ratio of the first relay lens 231 and the second relay lens 232. In actual use, the magnification of the 4f optical system is determined according to the lens pitch of the lens array and the focal array pitch of the prepared holographic optical element light combiner, so that the focal lengths of the first relay lens 231 and the second relay lens 232 are determined. The relay optical system may also be a relay optical system composed of other optical elements, which may be customized and designed according to specific functions.

The light combiner of the expanded eye pupil box can be prepared by the embodiment. The coherent light source 100 emits pure-quality and stable-spectrum laser light, the laser light generates wide-beam parallel light through the beam expanding collimation system 110, the parallel light is divided into two beams through the beam splitter 120, one beam is reference light which is reflected by the parallel light and irradiates the holographic dry plate 140 through the lens 150 and the first reflector 160 in an off-axis manner, and the other beam is signal light which is transmitted by the parallel light and irradiates the holographic dry plate 140 from the other side through the eighth reflector 210, the lens array 220 and the relay optical system 230. The interference of the reference light and the signal light on the holographic dry plate realizes the preparation of the holographic optical element light combiner for displaying the expansion of the eye pupil box by near eyes.

Example 3

An embodiment of the apparatus for manufacturing a holographic optical element combiner for near-eye display of eye pupil box expansion according to the present invention is shown in fig. 4, and includes a coherent light source 100, a beam expanding and collimating system 110, a beam splitter 120, a scanning signal light module 130, a holographic dry plate 140, a first lens 150, a first mirror 160, an eighth mirror 210, a moving platform driving system 170, a general controller 180, and an electronic shutter 190.

The coherent light source 100 is a laser in the visible light band, and is used for generating laser with pure quality and stable spectrum. The beam expanding and collimating system 110 is located behind the output end of the coherent light source, and is configured to perform collimating, beam expanding and filtering on the coherent light output by the coherent light source 100 to obtain parallel light of a wide light beam. The beam splitter 120 is a block beam splitter prism or a flat beam splitter, and splits parallel light collimated by the beam expanding and collimating system 110 into two beams, one beam is a reference beam which is transmitted by the parallel light and irradiates the holographic plate 140 through the first reflector 160, the eighth reflector 210 and the first lens 150, and the other beam is an object beam which is reflected by the parallel light and irradiates the holographic plate 140 through the scanning signal light module 130. The beam splitter 120 may be disposed before the beam expanding and collimating system 110, or may be disposed after the beam expanding and collimating system 110, and the specific disposition position needs to be determined according to actual requirements.

The holographic plate 140 is a holographic recording material for recording the amplitude and phase of light. The first lens 150 is a single lens, or a double-cemented lens, or a lens group composed of a plurality of lenses, and is disposed in the subsequent optical path of the beam splitter 120 for converging the parallel light as the reference beam. The first reflecting mirror 160 is a plane reflecting mirror, and is used for changing the direction of the light path so that the parallel light can be irradiated onto the eighth reflecting mirror 210. The scanning signal light module 130 is a system for adjusting an exposure light path, and is used for realizing the scanning of an optical convergence focus behind the holographic plate. The scanning signal optical module 130 is disposed in front of the movable platform driving system 170, and is connected to the movable platform driving system 170 after the beam splitter 120. The scanning signal optical module 130 is composed of a space moving platform 131 and a lens 133, and the lens 133 is disposed on the space moving platform 131.

In order to utilize the beam energy of the signal light more fully, the scanning signal light module 130 may also adopt the preferred structure 9000 shown in fig. 2 in embodiment 1. The scanning signal light module 9000 is preferably placed behind the beam splitter 120 to perform multi-focus scanning using the beam energy of the signal light sufficiently to perform interference recording with the reference light on the holographic plate 140. The preferred structure 9000 of the scanning signal optical module 130 is adjusted according to the actual requirement of the optical path to meet the actual requirement of the optical path. In this embodiment, the preferred structure 9000 of the scanning signal light module 130 may be configured to remove the third mirror 9001, directly irradiate the signal light split by the beam splitter 120 onto the fourth mirror 9002, sequentially reflect the fifth mirror 9003, the sixth mirror 9004, the seventh mirror 9005, and converge the fifth lens 9006 to form a focus on one side of the holographic plate 140, and drive the first motor 9009 and the second motor 9010 to form two-dimensional scanning of the focus position.

The moving platform driving system 170 is composed of a third motor 171 and a motor driver 172, and is used for controlling the movement of the space moving platform 131. The third motor 171 is connected to the space moving platform 131, and the motor driver 172 is connected to the overall controller 180. The general controller 180 is a computer for controlling the operation of the motor and the operation of the electronic shutter 190. Which is connected to motor driver 172 and electronic shutter 190. The electronic shutter 190 is an electromagnetic shutter, and is connected to the main controller 180 for controlling the on/off of the optical path. The overall controller 180 controls the operation of the electronic shutter 190 in conjunction with the operation of the space moving stage 131. The overall controller 180 controls the electronic shutter 190 to stop operating when the spatial moving stage 131 moves, and the overall controller 180 controls the electronic shutter 190 to operate when the spatial moving stage 131 stops. The attenuator 200 is a laser power attenuator, and is used for controlling the power of the laser in the optical path. The eighth reflecting mirror 210 is a plane reflecting mirror, and is used for changing the direction of the light path so that the parallel light can be irradiated onto the first lens 150. The first lens 150 and the eighth mirror 210 can also be replaced by a single curved mirror, and the functions of changing the propagation direction of light and converging parallel light beams can be simultaneously realized.

The light combiner of the expanded eye pupil box can be prepared by the embodiment. Firstly, setting the running speed of the space moving platform, determining the position of a focus required to pass through in the moving process of the space moving platform, and adjusting the initial position of the space moving platform. Then, a world coordinate system is initialized, a running path is planned, and exposure time T required by each focus position is calculated _i . When the space mobile platform moves according to the planned path until the first focus position needing exposure is reached, the preparation device brakes and keeps stationary for t time, and the master controller 180 receives the braking feedback of the space mobile platform and judges whether the space mobile platform is stable or not within the t time. When the system judges that the space moving platform is stable and immediately opens the electronic shutter 190 to connect the light path after the period of waiting T is finished, the electronic shutter 190 is kept open for a period of time T according to the calculated exposure time _i (ii) a The above steps are performed in a loop until all focus positions are exposed. In practice, each focus position may be cycledAnd the ring is exposed for multiple times, so that the diffraction efficiency of each focus position is relatively uniform. And finally, obtaining the holographic optical element light combiner for the pupil box expansion of the near-eye display.

Example 4

Fig. 5 shows an embodiment of a device for manufacturing a holographic optical element combiner for near-eye display of eye pupil box expansion, which includes a coherent light source 100, a beam expanding and collimating system 110, a beam splitter 120, a holographic dry plate 140, a first lens 150, a first mirror 160, an electronic shutter 190, an eighth mirror 210, a lens array 220, a relay optical system 230, and a diaphragm 240.

The coherent light source 100 is a laser in the visible light band, and is used for generating laser with pure quality and stable spectrum. The beam expanding and collimating system 110 is located behind the output end of the coherent light source, and is configured to perform collimating, beam expanding and filtering on the coherent light output by the coherent light source 100 to obtain parallel light of a wide light beam.

The beam splitter 120 is a block beam splitter or a flat plate beam splitter, and splits parallel light collimated by the beam expanding and collimating system 110 into two beams, one beam is a reference beam which is transmitted by the parallel light and off-axis irradiated to the holographic plate 140 through the first reflector 160, the eighth reflector 210 and the first lens 150, and the other beam is an object beam which is reflected by the parallel light and irradiated to the holographic plate 140 through the lens array 220. The beam splitter 120 may be disposed before the beam expanding and collimating system 110, or may be disposed after the beam expanding and collimating system 110, and the specific disposition position needs to be determined according to actual requirements. The holographic plate 140 is a holographic recording material for recording the amplitude and phase of light.

The lens 150 is a single lens, or a double-cemented lens, or a lens group composed of a plurality of lenses, and is disposed in the subsequent optical path of the beam splitter 120 for converging the parallel light as the reference beam. The first reflecting mirror 160 is a plane reflecting mirror for changing the direction of the light path so that the parallel light is obliquely incident on the holographic plate 140 to provide the divergent light thereto. The electronic shutter 190 is an electromagnetic shutter, and is connected to the main controller 180 for controlling the on/off of the optical path. The attenuator 200 is a laser power attenuator for controlling the power of the laser in the optical path, and the eighth mirror 210 is a plane mirror for changing the direction of the optical path so that the parallel light is irradiated onto the lens array 220. The first lens 150 and the eighth mirror 210 can also be replaced by a single curved mirror, and the functions of changing the propagation direction of light and converging parallel light beams can be simultaneously realized.

The lens array 220 is an array of a plurality of lenses, and is composed of a plurality of lenses arranged in a certain way, and is used for dividing a complete laser wavefront into a plurality of tiny parts in space, each part is focused on a focal plane by a corresponding small lens, and a plane composed of a series of focal points can be obtained by a series of lenses. Common arrangement modes of the lens array include single row type, M × N arrangement, full cloth type and the like; the shapes of the lens cells commonly found in lens arrays are hexagonal, square and circular. The specific arrangement and shape of the lens unit need to be selected according to the system requirements. The diaphragm 240 is an aperture diaphragm, and is disposed behind the beam splitter 120 for adjusting intensity of the light beam passing therethrough. The stop 240 may be an edge of a lens, a frame, or a specially configured screen.

The light combiner of the expanded eye pupil box can be prepared by the embodiment. The coherent light source 100 emits pure-quality and stable-spectrum laser light, the laser light generates wide-beam parallel light through the beam expanding collimation system 110, the parallel light is divided into two beams through the beam splitter 120, one beam is a reference beam which is reflected by the parallel light and irradiated to the holographic dry plate 140 through the first reflector 160, the eighth reflector 210 and the first lens 150 in an off-axis manner, and the other beam is an object beam which is converged to a series of focuses through the lens array 220 and then irradiated to the holographic dry plate 140. The reference beam and the object beam interfere to realize the preparation of the light combiner of the expanded eye pupil box.

Example 5

Embodiments 1 and 3 of the present invention provide a method for preparing a holographic optical element combiner for displaying eye pupil box expansion near an eye, and a specific flow is shown in fig. 6, where the method includes:

the first step is as follows: the running speed of the space moving platform can be set by matching with a speed reducer according to the rated rotating speed of the motor, the position of a focus required to pass through in the moving process of the space moving platform is determined, and the initial position of the space moving platform is adjusted.

The second step is that: initializing a world coordinate system, planning a running path according to the position of the focus array, and calculating the exposure time T required by each focus position according to system parameters such as exposure light intensity, a holographic dry plate, the focus number of the focus array, single-point exposure times and the like _i (i is the focal position of the ith exposure).

The third step: and the space moving platform moves according to the planned path until the space moving platform reaches the first focus position needing exposure, the space moving platform is braked and keeps stationary for t time, and the master controller receives brake feedback of the space moving platform and judges whether the preparation device is stable or not within t time.

The fourth step: judging whether the space moving platform is stable, immediately opening the electronic shutter to switch on the light path after the period of time T is over, and keeping the electronic shutter open for a period of time T according to the calculated exposure time _i 。

The fifth step: and circularly performing the third step and the fourth step to circularly expose each focus position for multiple times, so that the diffraction efficiency of each focus position is relatively uniform.

And a sixth step: and stopping exposure, ending scanning, and performing bleaching post-treatment on the holographic dry plate to obtain the holographic optical element combiner for expanding the eye pupil box for near-eye display.

The movement time of the spatial movable stage in the third step may be calculated from the focal point position and the apparatus operation speed, or may be self-adjusted by feedback control. Available feedback means are contact switches, accelerometers or hall sensors, etc.

In the sixth step, different processing methods are adopted for the post-processing of the holographic dry plate according to the material of the holographic dry plate. Such as: the dry holographic plate of silver halide emulsion material requires post-processing of development, water washing, stop developing, fixing, water washing and drying. Holographic dry plates of dichromated gelatin material require first use (NH) ₄ ) ₂ Cr ₂ O ₇ Washing with the solution, soaking in hardening liquid of the same type, and washing with waterDehydrating with isopropanol, and drying, sealing and curing. The holographic dry plate made of the photopolymer material can be processed by a dry method, and compared with other materials, the holographic image recorded by the photopolymer has higher geometric fidelity, long storage time and difficult distortion.

Example 6

Embodiments 1 and 3 of the present invention provide a working timing chart of a method for manufacturing a holographic optical element combiner for displaying pupil box expansion near an eye, as shown in fig. 7, in an exposure process, scanning and repeated exposure can be performed on a focus array for a plurality of cycles, where a timing sequence of one cycle is: the space mobile platform runs for a certain time T according to the planned path ₀ When the movable platform reaches the exposure position and brakes, the master controller receives the brake feedback signal to judge whether the movable platform is stable after braking within T time, and the total controller judges whether the movable platform is stable after braking within T time ₀ The electronic shutter is in a closed state for + t time. The master controller judges that the space moving platform is braked and stabilized, then opens the electronic shutter and keeps opening T _i Time, when the spatially moving platform remains stationary. And finishing two-dimensional scanning of the focal array according to the periodic process, and carrying out multiple exposure of not less than one period to realize the preparation of the holographic optical element light combiner for displaying the expansion of the eye pupil box by near eyes. The scanning path may be a ping-pong path, a line-by-line scanning or a column-by-column scanning.

Embodiments 2 and 4 of the present invention provide a schematic flowchart of a method for manufacturing a holographic optical element combiner for displaying eye pupil box expansion near an eye, as shown in fig. 8, the method includes:

the first step is as follows: and calculating the exposure time t and the exposure intensity I required by preparing the holographic optical element combiner with the expanded eye pupil box according to system parameters such as the holographic dry plate and the like.

The second step: the attenuator is adjusted until the beam intensities of the reference light and the signal light, respectively, irradiated on the hologram dry plate satisfy the calculated exposure intensity I.

The third step: and opening the electronic shutter to switch on the light path according to the exposure time t calculated in the first step and keeping opening for the time t.

The fourth step: and closing the electronic shutter to finish exposure, and carrying out bleaching post-treatment on the holographic dry plate to obtain the holographic optical element light combiner for expanding the eye pupil box for near-eye display.

In the fourth step, different processing methods are adopted for the post-processing of the holographic dry plate according to the material of the holographic dry plate. Such as: the dry holographic plate of silver halide emulsion material requires post-processing of development, water washing, stop developing, fixing, water washing and drying. Holographic dry plates of dichromated gelatin material require first use (NH) ₄ ) ₂ Cr ₂ O ₇ Washing with the solution, soaking in hardening liquid of the same kind, washing with water, dewatering with isopropanol, drying, sealing and curing. The holographic dry plate made of the photopolymer material can be processed by a dry method, and compared with other materials, the holographic image recorded by the photopolymer has higher geometric fidelity, long storage time and difficult distortion.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in a reasonable order, and there are many other variations of the different aspects of the invention as described above; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (8)

1. A preparation facilities of holographic optical element ware of closing light of near-to-eye display eye pupil case extension which characterized in that: including coherent light source (100), beam expanding collimation system (110), beam splitter (120), scanning signal light module (130), holographic dry plate (140), first lens (150), first speculum (160), moving platform actuating system (170), total controller (180), electronic shutter (190) and attenuator (200), constitute the preparation facilities that closes the optical ware based on the holographic optical element of scanning signal light module's near-to-eye display eye pupil case extension, wherein:

a coherent light source (100) for generating a pure quality, spectrally stable laser light;

the beam expanding and collimating system (110) is positioned behind the output end of the coherent light source (100) and is used for collimating, expanding and filtering coherent light output by the coherent light source (100) to obtain parallel light of a wide light beam;

the beam splitter (120) is a block beam splitter prism or a flat plate beam splitter and divides parallel light passing through the beam expanding and collimating system (110) into reference light and signal light;

the scanning signal optical module (130) is used for realizing the scanning of an optical convergence focus behind the holographic dry plate and is connected with a mobile platform driving system (170);

the holographic dry plate (140) is a holographic recording material for recording the amplitude and phase of light;

the first lens (150) is a single lens, a double cemented lens, or a lens group composed of a plurality of lenses, for converging parallel light as a reference beam;

the first reflector (160) is a plane reflector and is used for changing the direction of the light path so that the divergent light is obliquely incident and irradiated on the holographic dry plate (140);

the moving platform driving system (170) is composed of a third motor (171) and a motor driver (172) together, is used for controlling the movement of the space moving platform (131), and is connected with the scanning signal optical module (130) and the master controller (180);

the master controller (180) is used for controlling the operation of the motor and the working state of the electronic shutter (190) and is connected with the mobile platform driving system (170) and the electronic shutter (190);

the electronic shutter (190) is combined with the working state of the scanning signal optical module (130) to control the on-off of the optical path and is connected with the master controller (180);

the attenuator (200) is used for controlling the power of the laser in the light path.

2. The apparatus for preparing a holographic optical element combiner for near-eye display of eye pupil box expansion according to claim 1, wherein: the scanning signal optical module (130) includes: a space moving platform (131), a second reflector (132) and a fourth lens (133); wherein, the second reflector (132) and the fourth lens (133) are fixed on the space moving platform (131), and the fourth lens (133) is arranged behind the second reflector (132); the scanning signal optical module (130) is arranged behind the beam splitter (120), is connected with the mobile platform driving system (170), and is driven by the mobile platform driving system (170) to perform two-dimensional scanning.

3. The apparatus for preparing a holographic optical element combiner for near-eye display of eye pupil box expansion according to claim 1, wherein: the scanning signal optical module (130) is composed of a third reflector (9001), a fourth reflector (9002), a fifth reflector (9003), a sixth reflector (9004), a seventh reflector (9005), a fifth lens (9006), a first support (9007), a second support (9008), a first motor (9009) and a second motor (9010); the third reflector (9001), the fourth reflector (9002), the fifth reflector (9003), the sixth reflector (9004) and the seventh reflector (9005) are plane reflectors, light split by the beam splitter (120) sequentially passes through the third reflector (9001), the fourth reflector (9002), the fifth reflector (9003), the sixth reflector (9004) and the seventh reflector (9005) for reflection, and then passes through the fifth lens (9006) to form a convergent light beam; wherein:

the fourth reflector (9002) and the fifth reflector (9003) are fixed on a second support 9008;

the sixth reflector (9004), the seventh reflector (9005) and the fifth lens (9006) are fixed on the first support (9007);

the first motor (9009) and the second motor (9010) are stepping motors or servo motors and are respectively used for controlling the position and the height of the first support (9007) and driving the convergent light beam to synchronously perform two-dimensional scanning.

4. A preparation facilities of holographic optical element ware of closing light of near-to-eye display eye pupil case extension which characterized in that: including coherent light source (100), beam expanding collimation system (110), beam splitter (120), holographic dry plate (140), first lens (150), first speculum (160), electronic shutter (190), attenuator (200), eighth speculum (210), lens array (220), relay optical system (230), constitute the preparation facilities that closes the light ware based on holographic optical element that the nearly eye of lens array shows that eye pupil case expands, wherein:

a coherent light source (100) for generating a pure quality, spectrally stable laser light;

the beam expanding and collimating system (110) is positioned behind the output end of the coherent light source (100) and is used for collimating, expanding and filtering coherent light output by the coherent light source (100) to obtain parallel light of a wide light beam;

the beam splitter (120) is a block beam splitter prism or a flat plate beam splitter and divides parallel light passing through the beam expanding and collimating system (110) into reference light and signal light;

the holographic dry plate (140) is a holographic recording material for recording the amplitude and phase of light;

the first lens (150) is a single lens, a double cemented lens, or a lens group composed of a plurality of lenses, for converging parallel light as a reference beam;

the first reflecting mirror (160) is a plane reflecting mirror and is used for changing the direction of an optical path so that divergent light is obliquely incident and irradiated on the holographic dry plate (140);

the electronic shutter (190) is combined with the working state of the scanning signal optical module (130) to control the on-off of the optical path;

the attenuator (200) is used for controlling the power of the laser in the light path;

the eighth reflecting mirror (210) is a plane reflecting mirror for changing the direction of the light path so that the parallel light passes through the lens array (220);

the lens array (220) is an array structure formed by a plurality of lenses and is used for spatially dividing a complete laser wavefront into a plurality of tiny parts, and each part is focused on a focal plane by the corresponding small lens so as to obtain a plane formed by a series of focal points;

the relay optical system (230) is used for imaging the focal point array formed by the lens array (220) to the other side of the holographic dry plate (140).

5. The apparatus for preparing a holographic optical element combiner for near-eye display of eye pupil box expansion according to claim 4, wherein: the relay optical system (230) is composed of a first relay lens (231) and a second relay lens (232); the back focal plane position of the lens array (220) is in conjugate relation with the focal plane position required by the light combiner.

6. A method for preparing a holographic optical element combiner for near-eye display eye pupil box expansion, which adopts the preparation device of the holographic optical element combiner for near-eye display eye pupil box expansion based on the scanning signal optical module set in claim 1, and is characterized by comprising the following steps:

the first step is as follows: the running speed of the space moving platform can be set by matching with a speed reducer according to the rated rotating speed of the motor, the position of a focus required to pass through in the moving process of the space moving platform is determined, and the initial position of the space moving platform is adjusted;

the second step is that: initializing a world coordinate system, planning a running path according to the position of the focus array, and calculating the exposure time T required by each focus position according to system parameters such as exposure light intensity, a holographic dry plate, the focus number of the focus array, single-point exposure times and the like _i Wherein i is the focal position of the ith exposure;

the third step: the space moving platform moves according to the planned path until the first focus position needing exposure is reached, the space moving platform is braked and kept static for t time, and the master controller receives brake feedback of the space moving platform and judges whether the space moving platform is stable or not within the t time;

the fourth step: judging whether the space moving platform is stable, immediately opening the electronic shutter to switch on the light path after the period of time T is over, and keeping the electronic shutter open for a period of time T according to the calculated exposure time _i ；

The fifth step: circularly executing the third step and the fourth step to circularly expose each focus position for multiple times, and ensuring that the diffraction efficiency of each focus position is relatively uniform;

and a sixth step: and ending the scanning after stopping the exposure, and carrying out bleaching post-treatment on the holographic dry plate to obtain the holographic optical element combiner for the pupil box expansion of the near-to-eye display.

7. The method for preparing a holographic optical element combiner for near-eye display of eye pupil box expansion according to claim 6, wherein: in the second step, in order to ensure that the light combiner has better diffraction efficiency on the whole and ensure that the diffraction efficiency of each focus position is relatively uniform, exposure is carried out for each focus position for multiple times in a circulating manner.

8. A method for preparing a holographic optical element combiner for near-eye displaying eye pupil box expansion, which adopts the preparation device of the holographic optical element combiner for near-eye displaying eye pupil box expansion based on the micro-lens array, and is characterized by comprising the following steps:

the first step is as follows: calculating exposure time t and exposure intensity I required for preparing a holographic optical element combiner with expanded eye pupil according to system parameters such as a holographic dry plate;

the second step is that: adjusting the attenuator until the beam intensities of the reference light and the signal light irradiated on the holographic dry plate satisfy the calculated exposure intensity I;

the third step: opening the electronic shutter to switch on the light path according to the exposure time t calculated in the first step and keeping opening for the time t;

the fourth step: and closing the electronic shutter to finish exposure, and carrying out bleaching post-treatment on the holographic dry plate to obtain the holographic optical element light combiner for expanding the eye pupil box for near-eye display.

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