CN117687202A - Laser projection display system and optimization method thereof - Google Patents
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Abstract
The invention discloses a laser projection display system and an optimization method thereof, wherein a convex lens is not arranged at the rear end of a phase light modulator, the phase of an original convex lens acting on a light field is used as an additional phase to be superposed on the phase light modulator, a DMD chip is arranged at the focal plane position of the original convex lens, and the additional phase is superposed and loaded on the phase light modulator with a phase hologram of a target image, so that a light beam is modulated by the phase light modulator to form a diffraction reproduction image on the DMD chip, the DMD chip modulates the diffraction reproduction image and forms the target image through a projection lens, thereby avoiding the influence of zero-order interference light spots on imaging quality and simplifying the light path design of the system; the invention also carries out downsampling and refocusing on the target image to accelerate the limit recovery algorithm, and the target image is almost aligned with the DMD chip in time sequence, so that the real-time modulation of the illumination light field is realized; the problem of aspect ratio distortion of diffraction replicas is solved by preprocessing the target image.
Description
Technical Field
The invention belongs to the technical field of laser projection, and particularly relates to a dynamic range optimization method for a laser projection display system and the laser projection display system.
Background
In the laser display field, the HDR (high dynamic range) can enrich the details of each dark part, the dark part is darker, the bright part is brighter, the detail colors are enriched, and the natural detail picture is restored.
The core component of the DLP (digital light processing) projection system is a Digital Micromirror Device (DMD), and a PLM (phase space light modulator) device can efficiently modulate the distribution of illumination light fields of the DMD, so that the light fields of the illumination light to the DMD are approximate to the image distribution to be displayed, and the HDR image display can be realized after the DMD modulates the input image.
The PLM imaging at the DMD is diffraction imaging, the dynamic range is enlarged, the brightness limitation caused by the power of a laser light source is broken through in the local area of the DMD illumination, the PLM imaging can be increased to a plurality of times of the brightness of the DMD when the DMD uniformly illuminates, and the lower brightness image display can be realized through light field redistribution. However, firstly, although the aspect ratio of the whole effective area of the PLM and the DMD device is the same, because the micro-mirror structure of the PLM device is square, the diffraction reproduction aspect ratio is 1:1, and when light sources with different wavelengths are adopted for illumination, the size of an illumination light field formed at the DMD is inconsistent, so that the aspect ratio of the diffraction reproduction is inconsistent with the aspect ratio of the DMD device, and the illumination requirement of the DMD cannot be met; in the second aspect, the imaging quality is greatly affected by the existence of zero-order interference light spots; in the third aspect, the existing phase recovery algorithm for calculating PLM signals is too long to align with DMD in time sequence, and cannot modulate the illumination field in real time.
Disclosure of Invention
The invention provides a laser projection display system and an optimization method thereof, which eliminate zero-order interference light spots through optimization of a light path and an algorithm, improve imaging quality and simplify the light path; the phase recovery algorithm is accelerated by downsampling and refocusing the target image, and the target image is almost aligned with the DMD chip in time sequence, so that the real-time modulation of the illumination light field is realized; the problem of aspect ratio distortion of diffraction replicas is solved by preprocessing the target image.
The invention is realized by adopting the following technical scheme:
the invention provides a laser projection display system optimization method, which is applied to a laser projection display system, wherein the laser projection display system comprises:
a light source for providing a light beam;
the phase light modulator is used for adjusting the phase of light rays in the light beam provided by the light source;
the DMD chip is used for modulating the light beam subjected to the dimming of the phase space light modulator;
the projection lens is used for projecting and imaging the light beam modulated by the DMD chip;
in the laser projection display system, no convex lens is arranged between the phase light modulator and the DMD chip, and the method comprises the following steps:
calculating an additional phase; the additional phase is applied to the light field on the assumption that a convex lens is arranged at the rear end of the phase light modulator;
solving a phase hologram of the target image at the phase light modulator;
adding an additional phase to the solved phase hologram and loading the phase hologram on the phase light modulator so that a diffraction complex image is formed on the DMD chip after the light beam is subjected to phase modulation;
the DMD chip modulates the diffraction complex image and projects the diffraction complex image into the target image through the projection lens.
In some embodiments of the present invention, solving a phase hologram of a target image at the phase light modulator specifically includes:
downsampling the target image to 1/n of the original resolution;
calculating a phase hologram of the downsampled image;
copying the phase hologram of the downsampled image n times over n areas on the phase light modulator;
n images are converged into one image by superimposing blazed grating phase factors.
In some embodiments of the present invention, when superimposing blazed grating phase factors, the method comprises:
superposing blazed gratings with 2a periods in the transverse direction and the longitudinal direction; wherein a is the size of the micromirror of the phase light modulator;
the blazed grating phase factors of na and-na are superimposed on the phase holograms of the different areas, respectively.
In some embodiments of the invention, prior to solving the phase hologram of the target image at the phase light modulator, the method further comprises:
compressing the width of the target image to M/N, and filling the gray value of the spare pixel with 0; wherein M and N are aspect ratios of the target image; or alternatively, the first and second heat exchangers may be,
setting N x N micromirrors of the phase light modulator, and placing a target image of M: N in a black matrix image of N x N.
In some embodiments of the invention, prior to solving the phase hologram of the target image at the phase light modulator, the method further comprises:
scaling the target image, wherein the R channel subgraph is scaled according to a1, and the G channel subgraph is scaled according to a 2; a1 =λ B /λ R ，a2＝λ B /λ G ，λ B 、λ R And lambda (lambda) G The blue laser wavelength, the red laser wavelength, and the green laser wavelength, respectively.
A laser projection display system is presented, comprising:
a light source for providing a light beam;
the phase light modulator is used for adjusting the phase of light rays in the light beam provided by the light source;
the DMD chip is used for modulating the light beam subjected to the dimming of the phase space light modulator;
the projection lens is used for projecting and imaging the light beam modulated by the DMD chip;
no convex lens is arranged between the phase light modulator and the DMD chip, and the system further comprises:
an optical path adjusting unit for calculating an additional phase; the additional phase is applied to the light field on the assumption that a convex lens is arranged at the rear end of the phase light modulator;
a phase calculation unit for solving a phase hologram of the target image at the phase light modulator;
a diffraction control unit for loading the additional phase superimposed on the solved phase hologram on the phase light modulator so that the light beam forms a diffraction replica image on the DMD chip after phase modulation is performed;
the DMD chip modulates the diffraction complex image and projects the diffraction complex image into the target image through the projection lens.
In some embodiments of the present invention, the phase calculation unit solves a phase hologram of a target image at the phase light modulator, specifically including:
downsampling the target image to 1/n of the original resolution;
calculating a phase hologram of the downsampled image;
copying the phase hologram of the downsampled image n times over n areas on the phase light modulator;
n images are converged into one image by superimposing blazed grating phase factors.
In some embodiments of the present invention, the phase calculation unit, when superimposing blazed grating phase factors, comprises:
superposing blazed gratings with 2a periods in the transverse direction and the longitudinal direction; wherein a is the size of the micromirror of the phase light modulator;
the blazed grating phase factors of na and-na are superimposed on the phase holograms of the different areas, respectively.
In some embodiments of the invention, the system further comprises a first image preprocessing unit for compressing the width of the target image to M/N, the blank pixel gray values being padded with 0, prior to solving the phase hologram of the target image at the phase light modulator; wherein M and N are aspect ratios of the target image; or, setting N micro mirrors using the phase light modulator, and placing the target image of M: N in the black matrix image of N.
In some embodiments of the invention, the system further comprises a second image preprocessing unit for scaling the target image before solving the phase hologram of the target image at the phase light modulator, wherein the R channel subgraph is scaled by a1 and the G channel subgraph is scaled by a 2; a1 =λ B /λ R ，a2＝λ B /λ G ，λ B 、λ R And lambda (lambda) G Is divided into a blue laser wavelength, a red laser wavelength, and a green laser wavelength.
Compared with the prior art, the invention has the advantages and positive effects that: in the laser projection display system and the optimization method thereof, the convex lens is not arranged at the rear end of the phase light modulator, the phase of the original convex lens acting on the light field is used as an additional phase to be superposed on the phase light modulator, the DMD chip is arranged at the focal plane position of the original convex lens, and the additional phase and the phase hologram of the target image are superposed and loaded on the phase light modulator, so that the light beam is modulated by the phase light modulator to form a diffraction reproduction image on the DMD chip, the DMD chip modulates the diffraction reproduction image and forms the target image by the projection lens, and the influence of zero-order interference light spots on the imaging quality is avoided, and meanwhile, the light path design of the system is simplified.
Furthermore, the invention shortens the execution time of the phase recovery algorithm by adopting a mode of calculating the phase hologram after the down-sampling of the target image, and then on the phase modulation device, the phase hologram obtained after the down-sampling is refocused by a mode of copying the phase hologram in a partitioning way and superposing the blazed grating phase factor to obtain the target image before the down-sampling, so that the signal regulated by the phase light modulator is almost aligned with the DMD chip in time sequence, and the real-time modulation of the illumination light field is realized.
Furthermore, the invention enables the aspect ratio of the diffraction reproduction image to be consistent with the target image through preprocessing the target image, so that the phase light modulator can meet the illumination requirement of the DMD chip.
Other features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention, which is to be read in connection with the accompanying drawings.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a system architecture of a laser projection display system according to the present invention;
FIG. 2 is a schematic illustration of the steps of the method for optimizing a laser projection display system according to the present invention;
FIG. 3 is a schematic illustration of steps of a method for optimizing a laser projection display system according to the present invention;
FIG. 4 is a phase hologram calculated from a downsampled target image processed by the optimization method of the present invention;
FIG. 5 is a schematic illustration of a misplaced overlapping phase diagram obtained by n-time replication of n regions in the optimization process of the present invention;
FIG. 6 is a schematic diagram of a diffraction replica distribution in a prior art lens-containing laser projection display system;
FIG. 7 is a schematic representation of superimposed blazed gratings processed by the optimization method of the present invention;
FIG. 8 is a schematic representation of the final effect of superimposed blazed grating replication in the process of optimizing the present invention;
FIG. 9 is a schematic representation of target image preprocessing in the optimization method of the present invention;
FIG. 10 is a schematic representation of target image preprocessing in the optimization method of the present invention;
FIG. 11 is a schematic illustration of the steps performed on a target image in an optimization method of the present invention;
fig. 12 is a schematic diagram of a system component of a laser projection display system according to the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a laser projection display system and an optimization algorithm applied in the same, as shown in fig. 1, the laser projection display system comprises:
a light source 1 for providing a light beam; in the embodiment of the present invention, the laser light source is a laser light source, and the shaped light beam of the laser light source is directed to the phase light modulator 2. The laser light source comprises a red light source, a blue light source and a green light source, and emits parallel light, and the three light sources can emit light simultaneously or according to a set time sequence.
A phase light modulator 2 for modulating the phase of light in the light beam provided by the light source 1.
The DMD chip 3, i.e. the spatial light modulator, is used for modulating the light beam modulated by the phase light modulator 2. Specifically, the projected image is divided into R, G, B component sub-images according to R, G, B three primary colors, and the control circuit of the laser projection display system converts the signal of each color component sub-image into a corresponding driving signal to cause the DMD chip 3 to modulate the light beam irradiated thereon. In the present invention, the light beam modulated by the phase light modulator 2 is modulated.
And a projection lens 4 for projecting the light beam modulated by the DMD chip 3 onto a projection screen 5 for imaging.
In order to eliminate the problem of zero-order interference light spots in the laser projection display system, the rear end of the phase light modulator 2 is not provided with a convex lens, namely the convex lens behind the phase light modulator of the existing system is eliminated, and the laser projection display system is provided with an optimization method by combining the simplified light path structure as shown in fig. 2, and comprises the following steps:
s1: an additional phase is calculated.
The additional phase is a phase acting on the light field when the rear end of the phase light modulator 2 is provided with a convex lens, that is, the phase acting on the light field by the convex lens in the prior system is superimposed on the phase light modulator 2 in an additional phase mode, and the light beam is modulated by the phase light modulator 2 to replace the convex lens.
The length and width of the diffraction image are fλ/a, where f is the focal length of the convex lens, λ is the wavelength of the light source, and a is the size of the micromirror of the phase light modulator, so in the embodiment of the present invention, the additional phase of the convex lens acting on the light field directly takes the phase angle in the complex amplitude transformation coefficient of the convex lens; the complex amplitude transform coefficients are expressed as:
x and y are the image pixel coordinates, respectively.
S2: the DMD chip is adjusted to be positioned at the focal plane position of the convex lens.
The diffraction image and the focal plane of the convex lens are at the same depth, in the prior system, the convex lens is arranged behind the phase light modulator 2 to enable the light beam to be focused at the DMD chip, and the image is displayed at the DMD chip.
S3: the phase hologram of the target image at the phase light modulator is solved.
The GS algorithm can be adopted to reversely solve the phase distribution at the phase light modulator from the amplitude distribution of the target image at the DMD chip, and finally, the aim that the target image can be reproduced at the DMD chip only by the phase information is achieved.
As shown in fig. 3, the solving process includes: firstly, setting amplitude A1=1 at a phase light modulator, and randomly selecting phase phi 1=random; based on a diffraction formula, obtaining phase distribution phi 2 and amplitude distribution A2 At the DMD chip, reserving the phase distribution phi 2, and setting the amplitude as the amplitude At of the target image; according to the inverse diffraction formula, the amplitude A1 and the phase phi 1 transmitted back to the phase light modulator are obtained, the A1 = 1, and the phase information is reserved. The diffraction and the inverse diffraction in the above-described process are repeated until the error margin is satisfied or the maximum number of iterations is reached between the amplitude A2 of the diffraction image and the amplitude At of the target image.
In some embodiments of the invention, high-quality phase holograms generated by a target image and other algorithms are manufactured into a training set and a testing set, an existing deep learning network is used for solving the phase holograms of the target image at a phase light modulator, a loss function is optimized, trained weights are prestored in an FPGA, and the phase holograms of the target image can be predicted in real time by using the weights in the FPGA, so that the real-time dimming function of the phase light modulator can be realized.
S4: additional phases are superimposed on the solved phase hologram and loaded onto the phase light modulator.
The phase light modulator 2 as a micro mirror matrix controls the light beam to change the light field distribution according to the superimposed phase by moving up and down, and diffracts the complex image on the image surface of the DMD chip.
S5, the DMD chip modulates the diffraction complex image and projects a target image through a projection lens.
The invention cancels the convex lens at the rear end of the phase light modulator in the existing laser projection display system, the phase of the original convex lens acting on the light field is used as an additional phase to be superposed on the phase light modulator, the DMD chip is arranged on the focal plane position of the convex lens, and the additional phase mode and the phase hologram of the target image are superposed and loaded on the phase light modulator, so that the light beam is modulated by the phase light modulator to form a diffraction reproduction image on the DMD chip, the DMD chip modulates the diffraction reproduction image and forms the target image by the projection lens, and the light path design of the system is simplified while the influence of zero-order interference light spots on the imaging quality is avoided.
To increase the speed of operation of the phase reverse recovery algorithm to align it with the laser and DMD chip in time sequence, the present invention uses a method of rapidly generating phase holograms to increase the speed, the rapid generation method being as shown in fig. 3, comprising:
s31: the target image is downsampled to 1/n of the original resolution and a phase hologram of the downsampled image is calculated.
Where n is a positive integer greater than or equal to 2, calculating a small-sized phase hologram can greatly shorten the algorithm run time, e.g., when the target image resolution drops to 1/4 of the original, n=4, and the algorithm run time will be shortened by 75%. The embodiment shown in fig. 4 is a phase hologram calculated when the resolution drops to 1/4 of the original.
And S32, copying the phase hologram of the downsampled image on the phase light modulator for n times in n areas.
As shown in fig. 5, 4 areas are divided on the phase plane of the phase modulator, the phase hologram after downsampling is copied 4 times in these 4 areas, and 4 images overlapped with each other with a dislocation are obtained on the image plane of the DMD chip.
S33: n images are converged into one image by superimposing blazed grating phase factors.
The convergence of n images into 1 image is achieved by superimposing a blazed grating phase factor in the phase hologram, the effect of which is a shifting of the light energy.
In the optical system of the phase light modulator with the lens, after the phase light modulator is loaded with the phase hologram calculated by the GS algorithm or obtained by deep learning, the distribution of diffraction reproduction is shown in fig. 6, and as is known from the bright line condition asin=kλ, k= ±1,2,3 … of interference, the first-order interference is located at ±1/a greatly in sin/λ, the reproduction of the first-order is located at 1/2a, where a is the micromirror size (length, width, etc.). The blaze condition of the blazed grating is 2dsinγ=λ, where d is the period of the blazed grating, γ is the blaze angle, and its physical meaning is: in order to meet the blazed condition, the blazed grating acts as a 1/d shift of the image.
It can be seen that the diffraction image can be shifted from 1/2a to zero order by only setting the blazed grating period d to be superimposed to 2 a. In the downsampled GS algorithm of the present invention, again taking n=4 as an example, the effect is shown in fig. 7 after superimposing blazed gratings of 2a period in the transverse and longitudinal directions.
According to analysis, the centers of the images are respectively positioned at (-1/4 a,1/4 a), (-1/4 a ), (1/4 a, -1/4 a) and (1/4 a ), so that blazed grating phase factors with periods of 4a and-4 a (the periods are negative and indicate that the arrangement directions of the blazed gratings are opposite from low to high) are respectively overlapped in holograms of different areas, and the reagglomeration of 4 diffraction images is achieved, and the final effect is shown in figure 8.
The method shortens the execution time of a phase recovery algorithm by adopting the mode of calculating the phase hologram after the down-sampling of the target image, then on a phase modulation device, the phase hologram obtained after the down-sampling is refocused by the mode of copying the phase hologram in a partitioning way and superposing the blazed grating phase factor to obtain the target image before the down-sampling, so that a signal regulated by a phase light modulator is almost aligned with a DMD chip in time sequence, and the real-time modulation of an illumination light field is realized.
In order to solve the problem, in some embodiments of the present invention, the aspect ratio of the diffracted complex image is consistent with the target image by preprocessing the target image, so as to solve the problem of distortion of the aspect ratio of the diffracted complex image, and the light beam modulated by the phase light modulator can meet the requirement of the DMD chip illumination, the preprocessing means includes:
1. the width of the target image is compressed to M/N and the spare pixel gray values are padded with 0.
Where M and N are aspect ratios of the target image, e.g., 16:10,16:9,4:3, etc.; that is, the width of the target image is stretched to M/N as shown in FIG. 9; after the target image with the stretching width is acted by the phase light modulator, the target image with the normal aspect ratio can be reproduced on the image plane of the DMD chip.
2. Setting N x N micromirrors using a phase light modulator, let M: the target image of N is placed in the black matrix image of n×n.
For example, for a 1280 x 800 resolution phase light modulator, using only 800 x 800 micromirrors, an M: N target image is scaled and then placed in an 800 x 800 black matrix image, as shown in fig. 10; the target image with normal aspect ratio can be reproduced on the image plane of the DMD chip after the black matrix image with the aspect ratio of 1:1 is acted by the phase light modulator.
Under light sources of different wavelengthsThe longer the wavelength is, the larger the size of the diffraction complex image is, so in order to obtain the target image with correct proportion, in some embodiments of the present invention, the target image is scaled, the whole image preprocessing flow is as shown in fig. 11, the R channel subgraph is scaled according to a1 scale, and the G channel subgraph is scaled according to a2 scale; a1 =λ B /λ R ，a2＝λ B /λ G ，λ B 、λ R And lambda (lambda) G Respectively a blue laser wavelength, a red laser wavelength and a green laser wavelength; taking 450nm, 532nm and 640nm laser combinations as examples, the calculation formula is as follows:
the scaled target image is further decomposed into an R-channel hologram, a G-channel hologram, and a B-channel hologram at the phase modulating device using a GS algorithm to calculate a phase hologram at the phase modulating device.
In combination with the above, the present invention may in one embodiment achieve the following optimizations for a laser projection display system: firstly, preprocessing and zooming are carried out on a target image to solve the problem of diffraction complex image distortion; the problem of eliminating zero-order interference fringes is further solved by simplifying the light path and loading the phase of the convex lens acting on the light field to the phase light modulator in an additional phase mode; and finally, the calculation speed of the phase recovery algorithm is improved by means of downsampling and refocusing the target image.
Based on the above, the laser projection display system provided by the present invention, as shown in fig. 12, further includes an optical path adjusting unit 6, a phase calculating unit 7, and a diffraction control unit 8; the optical path adjusting unit 6 is used for calculating the additional phase and adjusting the focal plane position of the DMD chip positioned on the convex lens; the phase calculation unit 7 is used for solving a phase hologram of the target image at the phase light modulator; the diffraction control unit 8 is used for superposing an additional phase on the solved phase hologram and loading the phase hologram on the phase light modulator so that a diffraction duplicate image is formed on the DMD chip after the light beam is subjected to phase modulation; the DMD chip modulates the diffraction complex image and projects the diffraction complex image into a target image through a projection lens.
In some embodiments of the present invention, the phase calculation unit 7 solves for a phase hologram of the target image at the phase light modulator, specifically comprising: downsampling a target image to 1/n of the original resolution; calculating a phase hologram of the downsampled image; copying the phase hologram of the downsampled image n times over n areas on a phase light modulator; n images are converged into one image by superimposing blazed grating phase factors.
In some embodiments of the invention, the phase calculation unit, when superimposing blazed gratings, comprises: superimposing blazed gratings with 2a periods in the transverse direction and the longitudinal direction; where a is the effective size of the micromirror of the phase light modulator; the blazed grating phase factors of na and-na are superimposed on the phase holograms of the different areas, respectively.
In some embodiments of the invention, the system further comprises a first image preprocessing unit 9 for compressing the width of the target image to M/N, the blank pixel gray values being padded with 0, before solving the phase hologram of the target image at the phase light modulator; wherein M and N are aspect ratios of the target image; or, n×n micromirrors using a phase light modulator are set, and a target image of M: N is placed in a black matrix image of n×n.
In some embodiments of the invention, the system further comprises a second image preprocessing unit 10 for scaling the target image before solving the phase hologram of the target image at the phase light modulator, wherein the R channel subgraph is scaled by a1 and the G channel subgraph is scaled by a 2; a1 =λ B /λ R ，a2＝λ B /λ G ，λ B 、λ R And lambda (lambda) G Is divided into a blue laser wavelength, a red laser wavelength, and a green laser wavelength.
Specific optimization methods have been described in detail and are not described here.
It should be noted that, in the specific implementation process, the above method part may be implemented by executing, by a processor in a hardware form, computer execution instructions in a software form stored in a memory, which is not described herein, and the program corresponding to the executed action may be stored in a computer readable storage medium of the system in a software form, so that the processor invokes and executes the operations corresponding to the above modules.
The computer readable storage medium above may include volatile memory, such as random access memory; but may also include non-volatile memory such as read-only memory, flash memory, hard disk, or solid state disk; combinations of the above types of memories may also be included.
The processor referred to above may be a general term for a plurality of processing elements. For example, the processor may be a central processing unit, or may be other general purpose processors, digital signal processors, application specific integrated circuits, field programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or may be any conventional processor or the like, but may also be a special purpose processor.
It should be noted that the above description is not intended to limit the invention, but rather the invention is not limited to the above examples, and that variations, modifications, additions or substitutions within the spirit and scope of the invention will be within the scope of the invention.
Claims (10)
1. A laser projection display system optimizing method is applied to a laser projection display system, and the laser projection display system comprises:
a light source for providing a light beam;
the phase light modulator is used for adjusting the phase of light rays in the light beam provided by the light source;
the DMD chip is used for modulating the light beam subjected to the dimming of the phase space light modulator;
the projection lens is used for projecting and imaging the light beam modulated by the DMD chip;
the method is characterized in that no convex lens is arranged between the phase light modulator and the DMD chip in the laser projection display system, and the method comprises the following steps:
calculating an additional phase; the additional phase is applied to the light field on the assumption that a convex lens is arranged at the rear end of the phase light modulator;
solving a phase hologram of the target image at the phase light modulator;
adding an additional phase to the solved phase hologram and loading the phase hologram on the phase light modulator so that a diffraction complex image is formed on the DMD chip after the light beam is subjected to phase modulation;
the DMD chip modulates the diffraction complex image and projects the diffraction complex image into the target image through the projection lens.
2. The method of claim 1, wherein solving the phase hologram of the target image at the phase light modulator, comprises:
downsampling the target image to 1/n of the original resolution;
calculating a phase hologram of the downsampled image;
copying the phase hologram of the downsampled image n times over n areas on the phase light modulator;
n images are converged into one image by superimposing blazed grating phase factors.
3. The method of optimizing a laser projection display system as claimed in claim 2, wherein when the blazed grating phase factor is superimposed, comprising:
superposing blazed gratings with 2a periods in the transverse direction and the longitudinal direction; wherein a is the size of the micromirror of the phase light modulator;
the blazed grating phase factors of na and-na are superimposed on the phase holograms of the different areas, respectively.
4. The method of claim 1, wherein prior to solving for the phase hologram of the target image at the phase light modulator, the method further comprises:
compressing the width of the target image to M/N, and filling the gray value of the spare pixel with 0; wherein M and N are aspect ratios of the target image; or alternatively, the first and second heat exchangers may be,
setting N x N micromirrors of the phase light modulator, and placing a target image of M: N in a black matrix image of N x N.
5. The method of claim 1, wherein prior to solving for the phase hologram of the target image at the phase light modulator, the method further comprises:
scaling the target image, wherein the R channel subgraph is scaled according to a1, and the G channel subgraph is scaled according to a 2; a1 =//>，a2=/>//>，/>、/>And->The blue laser wavelength, the red laser wavelength, and the green laser wavelength, respectively.
6. A laser projection display system comprising:
a light source for providing a light beam;
the phase light modulator is used for adjusting the phase of light rays in the light beam provided by the light source;
the DMD chip is used for modulating the light beam subjected to the dimming of the phase space light modulator;
the projection lens is used for projecting and imaging the light beam modulated by the DMD chip;
the system is characterized in that no convex lens is arranged between the phase light modulator and the DMD chip, and the system further comprises:
an optical path adjusting unit for calculating an additional phase; the additional phase is applied to the light field on the assumption that a convex lens is arranged at the rear end of the phase light modulator;
a phase calculation unit for solving a phase hologram of the target image at the phase light modulator;
a diffraction control unit for loading the additional phase superimposed on the solved phase hologram on the phase light modulator so that the light beam forms a diffraction replica image on the DMD chip after phase modulation is performed;
the DMD chip modulates the diffraction complex image and projects the diffraction complex image into the target image through the projection lens.
7. The laser projection display system of claim 6, wherein the phase calculation unit solves for a phase hologram of the target image at the phase light modulator, in particular comprising:
downsampling the target image to 1/n of the original resolution;
calculating a phase hologram of the downsampled image;
copying the phase hologram of the downsampled image n times over n areas on the phase light modulator;
n images are converged into one image by superimposing blazed grating phase factors.
8. The laser projection display system of claim 7, wherein the phase calculation unit, when superimposing blazed grating phase factors, comprises:
superposing blazed gratings with 2a periods in the transverse direction and the longitudinal direction; wherein a is the size of the micromirror of the phase light modulator;
the blazed grating phase factors of na and-na are superimposed on the phase holograms of the different areas, respectively.
9. The laser projection display system of claim 6, further comprising a first image preprocessing unit for compressing the width of the target image to M/N prior to solving the phase hologram of the target image at the phase light modulator, the spare pixel gray values being padded with 0; wherein M and N are aspect ratios of the target image; or, setting N micro mirrors using the phase light modulator, and placing the target image of M: N in the black matrix image of N.
10. The laser projection display system of claim 6, further comprising a second image preprocessing unit for scaling the target image prior to solving the phase hologram of the target image at the phase light modulator, wherein the R channel subgraph scales by a1 and the G channel subgraph scales by a 2; a1 =//>，a2=/>//>，/>、/>And->The blue laser wavelength, the red laser wavelength, and the green laser wavelength, respectively.
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