WO2011150863A1

WO2011150863A1 - Holographic wave guide display and generation method of holographic image thereof

Info

Publication number: WO2011150863A1
Application number: PCT/CN2011/075268
Authority: WO
Inventors: 谈顺毅
Original assignee: 江苏慧光电子科技有限公司
Priority date: 2010-06-04
Filing date: 2011-06-03
Publication date: 2011-12-08
Also published as: CN101881936A; CN101881936B

Abstract

A holographic wave guide display taking a planar wave guide as a display screen and a generation method of a holographic image adapting to the holographic wave guide display are disclosed. The holographic wave guide display comprises a wave guide (11) as the display screen and a holographic projection system (12) for inputting the holographic image to the wave guide (11). The wave guide (11) is provided with a light input face and a light output plane, and the incident light can be transmitted in the wave guide (11) until exiting the wave guide (11) from the light output plane. The exiting position of the light on the light output plane is determined by both the position of incident point and the incident angle of the light on the incident face. The holographic wave guide display of the invention adopts the wave guide as a display device, and can display the holographic image and be manufactured as an ultra-large screen.

Description

Holographic waveguide display and method for generating holographic image thereof

Field of invention

The present invention relates to an image display apparatus and method, and relates to a holographic waveguide display using a planar waveguide as a display screen and a method of generating a holographic image adapted to the holographic waveguide display. Background technique

Holographic display technology is a technique that converts an image into a diffraction pattern at a particular distance and illuminates the diffraction pattern using one or more monochromatic sources. After a certain distance of propagation, the diffraction pattern can be reduced to the original target image due to the diffraction and interference effects of light. Compared to ordinary projection and liquid crystal display technology, holographic projection has the following advantages:

1. Energy saving: Unlike the liquid crystal display that blocks unwanted light, the holographic display modulates and directs light. In theory, all incident light energy will be effectively utilized. According to statistics, the utilization rate of light energy of liquid crystal display is between 10 and 20%, while the holographic display using bin-phase modulation technology has a utilization rate of more than 40%, and multi-phase modulation technology (multi- Phase modulation ) can increase the utilization of light energy to over 90%. In addition, the laser source or photodiode source used in holographic projection has a very high energy conversion efficiency compared to the white light bulb used in conventional projection technology.

2. Small size and simple structure: Compared to conventional projectors, the aberration of the displayed image can be corrected by the computational hologram itself, thereby eliminating the need for a large and complex and expensive lens system for correcting the phase difference. In addition, for color images, the holographic projector uses three monochromatic sources of red and green baskets, and the chromatic aberration correction is much simpler than the ordinary projection using white light containing all spectra.

3. High stability: The traditional display technology displays the correspondence between the image and the projection chip or the display screen and the display image. If there is a dead pixel on the chip or the screen, the display image will have a bad point. The holographic projection shows a specially calculated hologram on the Spatial Light Modulator (SLM). The basic principle is that the screen will never produce a dead pixel. A pixel point of a holographic image corresponds to a certain spectral information on the screen image instead of a specific pixel point. Assuming that the spatial light modulator resolves to 1000x1000, a total of 1 million pixel points, the upper one of the dead pixels is caused by the displayed image. The change is 1 in 1 million without corresponding dead pixels, which is invisible to the naked eye, even if there are hundreds of dead pixels on the spatial light modulator. Its effect on the displayed image is only a few thousandths, which is hard to detect by the naked eye.

A tapered waveguide display using a conventional projector is reported in the patent CN1217539C, which has the advantage that the optical path required for conventional projection can be omitted, and its thickness is thinner than that of a conventional rear projection display, and can be compared with a liquid crystal plasma. The display is comparable. Since the waveguide can be made of inexpensive optical glass or transparent plastic plate, compared with conventional flat panel display technologies such as liquid crystal and plasma, the cost of producing a large-sized screen will be very low. In addition, since the waveguide itself does not contain any electronic components, the waveguide display is more robust and durable than liquid crystal, plasma, photodiode and the like. However, the conventional waveguide display uses conventional projection. In order to correct the phase difference chromatic aberration, the structure of the waveguide is complicated and not easy to manufacture. In addition, the bulky size of conventional projectors and complex lens systems limit their use in waveguide displays. Summary of invention

The technical problem to be solved by the present invention is to provide a holographic waveguide display capable of displaying a holographic image while using a waveguide as a display carrier, which can be manufactured into a large screen, low in cost, energy saving, environmentally friendly, and durable, and the holographic waveguide display A method of generating an adapted holographic image.

The holographic waveguide display of the present invention comprises a waveguide as a display screen and a holographic projection system for inputting a holographic image to the waveguide; the waveguide has a light input surface and a light output plane, and the incident light can propagate in the waveguide until it is output from the light The plane leaves the waveguide, and the exit position of the light on the light output plane is determined by the position of the incident point on the incident surface and the incident angle.

The initial shape of the side surface of the waveguide is triangular, and the front end apex angle is α. To save material, the unnecessary portion of the front end can be cut off to make it a wedge shape, and the rear end thereof is a light input surface at an angle β with the front light output plane. .

The first half of the waveguide is a display area, the second half is an image diffusion area, and the image diffusion area can be folded to the back of the display area to save space.

The holographic projection system includes a light source, a light source modulation module for phase or intensity modulating the light source and outputting a desired image.

The holographic projection system also includes a light source expansion correction module located between the light source and the input portion of the light source modulation module.

The holographic projection system can also include an image magnification correction module located at an output portion of the light source modulation module. The holographic projection system further includes a control module, the control module controls the switch of the light source and the output strength. When the light source modulation module is a device that can change the image displayed thereon, the control module can accept the input image and output accordingly. Holographic image to light source modulation module and synchronized with the light source output.

The control module can also include a holographic image generation module for synchronously converting normal images into holographic images. When the control module includes a holographic image generation module, it can receive a normal image and convert it into a holographic image; when the control module does not include the holographic image generation module, it can directly receive the holographic image generated by the external system.

The holographic image generating method of the present invention adapted to the wedge waveguide described above operates in the holographic image generating module or the external system described above, and the holographic image generating module or external system may be a single chip microcomputer, a digital chip (DSP), or a field programmable gate array. Electronic chip or computer such as (FPGA).

The holographic image generating method of the present invention adapted to the above wedge waveguide includes an inverse waveguide transform, and the inverse transform of the waveguide includes the following steps:

(1) adding a phase factor to the image to be displayed;

(2) dividing the full screen into one or more regions according to the principle that light from different angles is emitted in different regions;

(3) Perform Fourier transform or inverse Fourier transform on the image of the corresponding region, and take the corresponding band of the result to obtain the angular spectrum;

(4) The result of inverse propagation (3) ^ff , the angular spectrum of the propagation U _x y) = U _x y)xe where A = 2r/l, which is the wavelength of the incident light;

(5) Reverse the rotation of 4 (/"Λ) r / ² - ² ; (Because the holographic image is not sensitive to the angle of rotation, in most cases, satisfactory image quality can be obtained without rotation, so this step can also be omitted. )

(6) Calculating and compensating for the effects due to the air waveguide interface and the lens system;

(7) Perform inverse Fourier transform or Fourier transform on different spectra, and take only the spatial amplitude and phase distribution of the corresponding region. The spatial amplitude and phase distribution of all regions are superimposed.

In the step of inverse transform of the above waveguide, the order of step (1) and step (2) can be exchanged. In the step of inverse transform of the above waveguide, steps (6) to (7) may be replaced by the following steps: a. Calculating and compensating for the effects caused by different interfaces;

b. Perform inverse Fourier transform or Fourier transform on different spectra, and take only the spatial extent of the corresponding region Degree and phase distribution. Superimpose the spatial amplitude and phase distribution of all regions;

C. Calculate and compensate for the effects of the lens system.

In order to improve the display quality of the image, the holographic image generating method of the present invention may further be: first calculating an hologram by inverse transform of the input image, quantizing the hologram, and then calculating the quantized hologram in the light output plane by using a waveguide transform. Amplitude and phase, take its phase, and add to the original input image; recalculate the hologram; repeat the above steps until the set number of times is satisfied, and then output the obtained hologram to the light source modulation module; The following steps:

(1) obtaining an angular spectrum of the holographic image by inverse Fourier transform or Fourier transform, and dividing into one or more bands to obtain an angular spectrum of each band;

(2) Calculate and compensate for the effects of the lens and different interfaces;

(3) Rotate the result obtained in (2) / ² _ ² ; (Because the hologram image is not sensitive to the rotation angle, in most cases, satisfactory image quality can be obtained without rotation, so this step can also be omitted) (4) The result of propagation (3) Ό, the angular spectrum of the propagation U _x y) = U _x y)xe where A = 2r/ l, which is the wavelength of the incident light;

(5) Perform Fourier transform or inverse Fourier transform on each band, and take only the amplitude and phase distribution of the corresponding region;

(6) Superimposing the amplitude and phase distribution of each region to obtain the total amplitude and phase distribution.

In the above step of transforming the waveguide, steps (1) to (2) may be replaced by the following steps:

a. Calculate and compensate for the effects of the lens system;

b. The holographic image is inversely transformed by Fourier transform or Fourier transform to obtain the angular spectrum, and is divided into one or more bands to obtain the angular spectrum of each band;

c. Calculate and compensate for the effects of different interfaces.

In the above-described step of waveguide conversion, the order of steps (3) and (4) can be interchanged.

In order to further improve the display quality of the image, the holographic image generating method of the present invention can also quickly display the multi-frame nuance image in a short time by using the holographic image outputted to the illuminating module of the light source, and utilize the residual effect of the human eye to make it The superposition on the retina is used to reduce the error. The specific steps are as follows:

(1) Determine how many frame sub-images are displayed for each frame of the image, which is counted as M;

(2) Add a phase factor to the input image, and the initial phase factor can take a random phase. Determine each child The number of times the frame image needs to be iterated N;

(3) performing inverse transform of the waveguide to obtain a desired hologram;

(4) Quantizing the hologram according to the spatial light modulation device used to obtain a quantized hologram that can be displayed thereon;

(5) judging whether the number of iterations is reached, if yes, running step (6), if otherwise, performing the waveguide transformation, obtaining the amplitude and phase distribution of the display image corresponding to the quantized hologram, taking the phase thereof, adding the original input image, and jumping back Step (3);

(6) displaying the quantized hologram as a sub-frame on the light source modulation module;

(7) judging whether the display of all the sub-frames of the image is completed, if yes, inputting the next frame image, jumping back to step (1); if otherwise, performing the waveguide transformation, comparing the amplitude of the obtained image with the amplitude of the original input image, according to The resulting error modifies the intensity of the original input image and jumps back to step (2).

Compared with the ordinary projector, the holographic waveguide display of the invention has the advantages of small volume, low cost, energy saving, stable and not easy to be damaged. Compared with the conventional holographic projection technology, the present invention is combined with the waveguide display to make the product have a screen, which eliminates the optical path space required by the projector, and is similar in appearance and use to a conventional flat panel display. In addition, the combination of waveguides allows the product to be retrofitted into future applications for touch screens, transparent displays, 3D displays and more. DRAWINGS

1 is a schematic structural view of an embodiment of a holographic waveguide display of the present invention showing a side structure of a waveguide; FIG. 2 is a schematic plan view of the structure of FIG.

Figure 3 is a structural schematic view showing another embodiment of the holographic waveguide display of the present invention showing the side structure of the waveguide;

Figure 4 is a top plan view of Figure 3;

Figure 5 is a schematic diagram of a holographic projection system in accordance with one embodiment of the present invention;

6 is a schematic diagram of a holographic projection system according to another embodiment of the present invention;

Figure 7 is an executable light path diagram of the schematic diagram of Figure 6;

Figure 8 is a schematic diagram of holographic image generation of a wedge waveguide;

Figure 9 is a flow chart of the inverse transform of the waveguide; Figure 10 is a flow chart of waveguide conversion;

Figure 11 is a schematic diagram of a method of reducing holographic image errors.

Figure 12 shows a schematic view of an isotherm of a waveguide of the present invention. Detailed description of the invention

As shown in Figures 1 and 2, the holographic waveguide display of the embodiment of the present invention includes a waveguide 11 as a display screen and a holographic projection system 12 for inputting a holographic image to the waveguide. The shape of the waveguide can be as shown in Fig. 1. The initial shape of the side surface is triangular, and the apex angle of the front end is α. To save material, the useless part of the front end can be cut off to make it a wedge shape. To facilitate light incidence, the back end of the waveguide is calculated. It can be designed as a plane at an angle β with the exit surface. In other words, in this embodiment, the light output plane of the waveguide of the present invention forms a fixed angle with the bottom surface, i.e., 01. The top view can be rectangular, triangular, or other shape that is easy to display. The latter half serves as an image diffusion area 111 (light propagation area), and the front half serves as a display area 112 for displaying an image. The rear half can also be folded to the back of the front half to save space (Figure 3, Figure 4). The shape of the waveguide display is the same as that of a normal flat panel display. There is an interface between the image diffusion area and the screen, which can be air. Or special media to ensure that light is only reflected on this interface without exiting. An anti-reflection coating (anti-reflective film) can be applied to the surface of the screen to ensure that all of the light will reach the exit angle and eliminate the effects of secondary reflection on the image.

Further, referring to Fig. 12, the waveguide of the present invention is a wedge-shaped plate in which a thick line is a straight line (broken line shown in Fig. 12). For example, the equation t = t ₀ + ar ₀ can be used, where t _{0 is} the thickness of the tip of the waveguide, a is a constant, and r ₀ is the distance from the point on the surface of the waveguide to the end line of the waveguide, because the waiting line is a straight line, and its thickness Does not change with distance from the center point. The waveguide of the present invention can be applied to a holographic projection system by adopting the above-mentioned wedge-shaped plate having a straight line, and the wedge waveguide having a straight isotropic line does not generate astigmatism and the like, and the shape is different from the conventional tapered waveguide. Simple and easy to manufacture, low cost, combined with the holographic projection system, it can eliminate image breakage problems in wedge-shaped waveguides with straight lines. As shown in Figures 5 and 6, the holographic projection system includes the following parts:

Light source: The light source uses a monochromatic light source such as a laser or photodiode. Color images can be obtained by using three monochromatic sources of red, green, and basket.

Light source expansion correction module and image magnification correction module: They are used to expand and correct the laser and to amplify and correct the output image of the light source modulation module. For example, the expanded light source can be corrected for parallel light. The light modulation module is illuminated and a lens system is used to amplify the output hologram.

Light Source Modulation Module: This module is used to phase or intensity the light source and output the desired image. It can be a liquid crystal on silicon system chip (LCOS), a digital micromirror device (DMD), or a hologram, a grating array, or the like. If a liquid crystal system chip (LCOS) or a digital micromirror device (DMD) is used, the hologram displayed thereon can be switched at high speed through the control module, thereby realizing the output of the dynamic video stream.

Control module: The control module is used to control the switch and output strength of the light source. It can be composed of electronic chips and circuits such as single chip microcomputer, digital chip (DSP), field programmable gate array (FPGA). If the spatial light modulation module uses a liquid crystal on silicon system chip (LCOS), a digital micromirror device (DMD), etc., to convert the device on which the image is displayed, the control module will accept the input image and output the hologram to the spatial light accordingly. Modulate the module and synchronize it with the output of the light source. In addition, if the input is a normal image, the control module will include a hologram generating module to realize real-time synchronous conversion of the ordinary video to the hologram, and then output the generated hologram to the spatial light modulation module, and keep the light source synchronized with it (eg Figure 5 ). If the input to the control module is a holographic image, this module may not contain a hologram conversion module. The control module directly outputs the input holography image to the spatial light modulation module, and keeps the intensity of the light source synchronized with the corresponding image (Fig. 6), and the conversion process of the normal video stream to the hologram video stream can be completed by an external computer.

Figure 7 shows a possible specific implementation of the optical path of the schematic shown in Figure 5. The light source uses three kinds of monochromatic lasers of red, green and basket, and the source beam expansion correction and image enlargement correction module are composed of lenses 1 to 5. The lenses 1, 2, and 3 are light source correction lenses, and the corresponding light sources are converted from non-planar waves to plane waves. The lenses 4, 5 form an inverse telescope structure for amplifying the holographic image output by the light source modulation module. The spatial light modulation module enables phase modulation of light by using a liquid crystal on-chip (LCOS) on the silicon to add a polarizer. The control module uses a digital chip (DSP) or a field programmable gate array (FPGA) to realize the function of converting the input ordinary image into a holographic image in real time, and synchronizing the output of the light source and the hologram.

There are a variety of optical paths that can be used to implement the principles of Figure 5 or 6, and Figure 7 is only one of them. The principle of FIG. 5 or 6 can also be realized by configuring a light source modulation device for each color laser. For example, the entire system contains three silicon liquid crystal system chips (LCOS), respectively modulating red, green, and basket light sources to improve Image Quality.

The propagation of light in a waveguide is different from the mode of propagation in free space. Therefore, hologram generation in the waveguide will also differ from the generation method in free space. In the waveguide of the wedge structure of the present invention, incident light of different angles can be equivalently projected onto an exit plane that rotates at different angles. Figure 8 is a side view of the wedge waveguide, the surface of which There is a coating, the apex angle of the waveguide is ", the height is, the length is. The incident angle of the light after entering the waveguide is calculated, and the projection of the light of the angle "+ ² " can be equivalent to the projection on the surface of the waveguide after the rotation, and the angle The light belonging to (θ _ίη - 2α, θ _ίη ] is equivalent to the surface of the waveguide projected after the rotation ² + 1)". Fig. 9 is a method of generating a waveguide hologram image, which is referred to as an inverse waveguide transform in the present invention. The steps are as follows:

1. For the desired image τ ( ^χ , add phase factor τ( ^χ , ^Χβ; ' ^Φ ^), initial phase factor

Φ(χ, can be a random phase;

2. According to the principle that light from different angles is emitted in different areas, the whole screen is divided into two areas (the areas can be partially overlapped, that is, the incident light at different angles is emitted at the same point on the screen due to different incident points), respectively

(χ =^ ^(x ^" ^Rn should be in the N bands of the angular spectrum" ^(Χ '^ ^{= (Χ} ' ^{Χ £; Φ} ( ) ^χΡ " ^(χ ' , where " , ⁰ ( ^χ ' ^ ^ spatial filter Function, "for the corresponding screen area;

3. Perform the Fourier transform or the inverse Fourier transform on the image of the region η, and take only the η band of the result to obtain the angular frequency.

, where} is the Fourier or Fourier inverse

Q _n (f _xy ) = { ^{1 (fx y)GS} "

Transform, ⁰ , Uy) n , the role of the angular spectrum filter, for the corresponding band; 4. inverse propagation 4 ('). The angular spectrum after propagation A f " f ⁼ f " f 乂 a small ^{(%) 2} " ^(3⁄4) where A = L/2r, the wavelength of the incident light, J is the side of the waveguide incident surface intersecting the screen to its triangle The large separation of the vertices of the structure (as shown in Figure 8);

5. Calculate the result of reverse rotation / ² _ ² (this step can also be omitted if the rotation angle is not large);

6. Calculate and compensate for the effects of air due to the air waveguide interface and the lens system;

7. Superimpose all the angular spectra, then inverse Fourier transform or Fourier transform to obtain the amplitude and phase distribution of the space. Perform inverse Fourier transform or Fourier transform on different spectra, and take only the spatial amplitude and phase distribution of their corresponding regions. The spatial amplitude and phase distribution of all regions are superimposed.

The order of the steps in this method can be adjusted to suit different systems. Finally, one of the amplitudes or phases is selected and the hologram is generated according to the spatial light modulator used. For example, for a binary phase modulated spatial light modulator, a quantization method is to take all the points whose phase is greater than 0, less than A point of 0 takes - / ² to get a binary hologram. Steps 3, 4, 6 can be expressed mathematically as

"H {r( , ')x _e ^ ⁽ ^ ⁾ x _J P„( , ')}x^x _e ^ttsm2 "^ ¹ " ^(1⁄2)2 " ^(3⁄4)2

=

:

=

* x _e ^sm2 — ^μΛ)2 — ^{( )2} } where * is a convolution operation, since ^{F {S} " ^{e }F {Q} " ^{e }} is independent of the specific image, so it can be calculated and stored in advance, so one volume can be used. The product calculation replaces the two Fourier transforms to increase the speed of the operation. In addition, the above method is reversible, and only a few minor modifications are needed to calculate the waveguide transformation of the hologram displayed on the screen (Fig. 10):

(1) The hologram is inversed by Fourier transform or Fourier transform to obtain the angular spectrum, and is divided into one or more bands to obtain the angular spectrum of each band;

(3) Rotate the result obtained in (2) by τ/ ² _ ² "« (if the angle of rotation is not large, this step can also be omitted);

(4) The result of propagation (3) Ό , the angular spectrum U _x y) = U _x y)xe where A = 2r/ l, is the wavelength of the incident light;

(5) Perform Fourier transform or Fourier transform on each band, and take only the amplitude and phase distribution of the corresponding region;

The order of the above steps can be adjusted according to the situation. The quantization process will generate errors. In order to improve the image quality, the visual residual effect of the human eye and the high refresh rate of the electronic spatial light modulator can be used to achieve fast display of the image to reduce the quantization of the hologram on the electronic spatial light modulator. The error caused. For example, a liquid crystal system chip (LCOS) with a refresh rate of 1024 Hz per second can display 1024 frames per second. According to the normal video, 24 frames per second, each frame can be composed of 42 sub-images. There are subtle differences between images to compensate for the error between each other, due to The visual residual effect of the human eye, the resulting image will be of high quality. (patent application

An aberration correction method for two-dimensional holographic projection in free space is described in CN101310225A. The phase difference correction used in the present invention is based on a waveguide transform rather than a simple Fourier transform, which is significantly different from its existence. The waveguide hologram correction method of the present invention is shown in Fig. 11:

1. Enter a new frame of image to determine how many frame sub-images it consists of, counted as M

2. Add a phase factor to the input image. The initial phase factor can take a random phase. Determine the number of iterations N to calculate each sub-frame image.

3. Perform inverse waveguide transformation to obtain the desired hologram

4. Perform hologram quantization according to the spatial light modulation device to obtain a quantized hologram that can be displayed thereon. 5. Determine whether the iteration number is reached. If yes, run step 6. If the waveguide transformation is otherwise run, obtain the corresponding image corresponding to the quantized hologram. Amplitude and phase distribution, take the phase distribution, add 2 to the input image, and jump back to step 3

6. Display the quantized hologram as a sub-frame on the spatial light modulator

7. Determine whether to display all the sub-frames of this image. If yes, enter the next frame image and jump back to step 1. If the waveguide transformation is otherwise run, the amplitude of the obtained image is compared with the amplitude of the original input image, and the intensity of the original input image is finely modified according to the obtained error by a special method, and then jumps back to step 2.

Steps 2 to 5 are similar to the Gerchberg-Saxton or Liu-Taghizadeh method that can be used to calculate a normal hologram, using phase degrees of freedom to optimize the phase by iteration. Get a higher quality hologram. Step 7 implements feeding back the error generated by the quantization to the input image, and modifying the image displayed in the next sub-frame by a special method, so as to compensate for the error of the current sub-frame image.

Claims

Claim

A holographic waveguide display, characterized in that it comprises a waveguide (11) as a display screen and a holographic projection system (12) for inputting a holographic image to the waveguide; the waveguide having a light input surface and a light output plane The incident light can propagate in the waveguide until it exits the waveguide from the light output plane. The exit position of the light on the light output plane is determined by the position of the incident point on the incident surface and the incident angle. The side shape of the waveguide is Wedge shape, the rear end is the light input surface, and the front side is the light output plane.

2. A holographic waveguide display according to claim 1, wherein: said waveguide is a wedge-shaped plate having a straight line of equal thickness.

3. The holographic waveguide display according to claim 2, wherein: the first half of the waveguide is a display area (112), the second half is an image diffusion area (111), and the image diffusion area is folded to the back of the display area. .

4. A holographic waveguide display according to any one of claims 1 to 3, wherein: said holographic projection system comprises a light source, a light source modulation module for phase or intensity modulating the light source and outputting a desired image.

5. A holographic waveguide display according to claim 4, wherein: said holographic projection system includes a source beam expansion correction module located between the source and the input portion of the source modulation module.

6. A holographic waveguide display according to claim 4, wherein: said holographic projection system includes an image magnification correction module located at an output portion of the light source modulation module.

7. The holographic waveguide display according to claim 4, wherein: the holographic projection system further comprises a control module, the control module controls the switch and the output strength of the light source, and the light source modulation module converts the device on which the image is displayed. The control module accepts the input image and correspondingly outputs the holographic image to the light source modulation module and synchronizes it with the light source output.

8. The holographic waveguide display according to claim 7, wherein: said control module comprises a holographic image generating module for synchronously converting a normal image into a holographic image.

A holographic image generating method adapted to the waveguide display according to claim 2 or 3, characterized in that it comprises an inverse waveguide transform, and the inverse transform of the waveguide comprises the following steps:

(1) adding a phase factor to the image to be displayed;

(2) Divide the full screen into one or more zones according to the principle that light from different angles is emitted in different areas area;

(3) Perform Fourier transform or inverse Fourier transform on the image of the corresponding region, and take the corresponding band of the result to obtain the angular spectrum 4 ^(/ ");

(4) The result of the inverse propagation step (3), ^ff , the angular spectrum of the propagation U _X y) = U _X y)Xe where A = 2r/ l, which is the wavelength of the incident light, where "the light is experienced in the waveguide The number of double total reflections, L is the distance from the apex of the extended portion of the wedge-shaped waveguide triangle to the end of the waveguide, "the apex angle of the extension of the wedge-shaped waveguide triangle;

(5) Reverse the rotation of (( '^) /2_2w« ;

(7) Perform inverse Fourier transform or Fourier transform on different spectra, and take only the spatial amplitude and phase distribution of the corresponding regions, and then superimpose the spatial amplitude and phase distribution of all regions to obtain a holographic image.

10. The holographic image generating method according to claim 9, wherein: said inverse waveguide transform is performed by omitting said step (5) in a step thereof. .

11. The holographic image generating method according to claim 9, wherein: said inverse waveguide transform is to perform steps (1) and (2) in the step thereof. The order of the exchanges.

12. The holographic image generating method according to claim 9, wherein: said inverse waveguide transform is performed in steps (6) to (7). Replace by the following steps:

a. Calculate and compensate for the effects of different interfaces;

b. Perform inverse Fourier transform or Fourier transform on different spectra, and take only the spatial amplitude and phase distribution of the corresponding regions. Superimpose the spatial amplitude and phase distribution of all regions;

c. Calculate and compensate for the effects of the lens system.

13. A holographic image generating method adapted to the waveguide display according to claim 2 or 3, wherein: the input image is first calculated by inverse transform of the waveguide according to any one of claims 9 to 12 to obtain a hologram, After quantification, the amplitude and phase of the quantized hologram in the light output plane are calculated by the waveguide transformation, and the phase is taken and added to the original input image; the hologram is recalculated; the above steps are repeated until the set number of times is satisfied. And outputting the obtained hologram to the light source modulation module described in claim 4; The waveguide transformation includes the following steps:

(3) Rotate the result obtained in (2) by / ² - ² to obtain the angular frequency 4 ( ');

(4) The result of propagation step (3) Ό, the angular spectrum of the propagation U _xy ) = AU _xy )xe where = ² / , is the wavelength of the incident light, where "the number of double total reflections experienced by the ray in the waveguide, L The distance from the apex of the extended portion of the wedge-shaped waveguide to the end of the waveguide, "the apex angle of the extension of the wedge-shaped waveguide triangle;

The hologram generating method according to claim 13, wherein the waveguide conversion is omitted in the step (3).

A holographic image generating method according to claim 13 or 2, wherein: said waveguide transform is performed in steps (1) to (2) Replace the following steps:

a. Calculate and compensate for the effects of the lens system;

c. Calculate and compensate for the effects of different interfaces.

The holographic image generating method according to claim 13, wherein: said waveguide transform is performed in steps (3) and (4) Order interchange.

The holographic image generating method according to any one of claims 13 to 16, wherein the holographic image outputted to the light source modulating module is processed as follows:

(2) Add a phase factor to the input image, and the initial phase factor can take a random phase to determine each sub- The number of times the frame image needs to be iterated N;

(3) Performing an inverse transform of the waveguide to obtain a desired hologram;

(5) Determine whether the number of iterations is reached. If yes, run step (6). If the waveguide transformation is otherwise run, obtain the amplitude and phase distribution of the displayed image corresponding to the quantized hologram, take the phase, add it to the original input image, and jump back. Step (3);

(7) Determine whether to complete the display of all the sub-frames of the image, if yes, input the next frame image, and jump back to step (1); if otherwise, run the waveguide transform, compare the amplitude of the obtained image with the amplitude of the original input image, according to The resulting error modifies the strength of the original input image and jumps back to step (2).