Laser projection display method and laser projection display system

Abstract

The application discloses a laser projection display method and a laser projection display system, a lens is arranged at the rear end of a phase spatial light modulator, a wedge prism array is arranged at the light exit side of the lens, a blazed grating phase and a spherical wave phase are superposed on an original phase diagram, the blazed grating phase is used for off-axis diffraction images, and the zero-order diffraction light is kept to propagate along the optical axis; the spherical wave phase makes the focusing positions of the off-axis diffraction images and the zero-order diffraction light stagger in depth; the final phase diagram is modulated by the phase spatial light modulator to form the off-axis diffraction images and the non-off-axis zero-order diffraction light, the zero-order diffraction light is focused on the non-light-transmitting center of the wedge prism array by the lens and is filtered out, and the off-axis diffraction images are folded back to the axis by the wedge prism array and are imaged on the digital micromirror device plane. The design of the application eliminates the influence of the zero-order diffraction light spot on the imaging quality, further expands the dynamic range, and improves the peak brightness of the backlight due to the integration of the multi-stage diffraction images.

Description

Technical Field

[0001] This invention belongs to the field of laser projection display technology, specifically, it relates to a laser projection display method and a laser projection display system. Background Technology

[0002] Existing laser projection display systems generally include, for example: Figure 1 As shown, it includes an RGB light source, a beam shaping device, a digital micromirror device (DMD), a projection lens, and a projection screen; its optical processing flow includes: the beam emitted by the RGB light source is shaped by the beam shaping device and then uniformly illuminates the DMD; the image content displayed by the DMD is projected onto the screen through the projection lens to complete the laser projection display.

[0003] HDR (High Dynamic Range) laser projection display systems, such as Figure 2 As shown, a phase spatial light modulator (PLM) is added before the DMD to modulate the phase of the laser source, thereby redistributing the energy of the DMD illumination field according to the image content to be displayed.

[0004] However, due to manufacturing defects in PLM, such as pixel spacing and surface encapsulation glass, some light rays are not diffracted after passing through the PLM, forming unmodulated light. When the PLM modulates the phase of the laser source, this unmodulated light exists in the form of zero-order diffracted light, which affects the uniformity and contrast when modulating the illumination field energy distribution of the DMD. Summary of the Invention

[0005] The purpose of this invention is to propose a laser projection display method and a laser projection display system. By adding a wedge prism array between the phase spatial light modulator and the digital micromirror device to eliminate zero-order diffraction light, the problem of the impact of zero-order diffraction spot on the imaging quality caused by the use of PLM to modulate the laser source in the laser projection display system is solved. Furthermore, by integrating multi-order diffraction images, the peak brightness of the backlight is improved, and the contrast range of the laser projection display system is further expanded.

[0006] The present invention is implemented using the following technical solutions:

[0007] A laser projection display method is proposed and applied to a laser projection display system, the laser projection display system comprising:

[0008] A laser light source is used to provide a beam of illumination;

[0009] A phase spatial light modulator is used to modulate the phase of an illumination beam.

[0010] Digital micromirror devices are used to modulate phase-modulated illumination beams to form display images;

[0011] A lens is positioned on the light-emitting side of the phase spatial light modulator;

[0012] A wedge-shaped prism array, with an opaque area at the center, is positioned at a distance from the light-emitting side of the lens. Place; among them, The focal length of the lens;

[0013] The method includes:

[0014] Calculate the original phase map of the target image;

[0015] Add a blazed grating phase and a spherical wave phase to the original phase diagram; the blazed grating phase is used to make the diffraction image propagate off-axis after the illumination beam is modulated by the phase spatial light modulator; the spherical wave phase is used to make the focal position of the off-axis diffraction image offset from the focal position of the zeroth order diffraction beam in depth.

[0016] The final phase map is loaded into the phase spatial light modulator; in which the zeroth order diffracted light is focused by a lens onto the opaque center of the wedge prism array and filtered out, and the off-axis diffracted image is refracted to the plane of the digital micromirror device for imaging by the wedge prism array.

[0017] In some embodiments of the present invention, a blazed grating phase and a spherical wave phase are added to the phase diagram, specifically including:

[0018] The GS algorithm is used to calculate the phase map of the target image;

[0019] Calculate the blazed grating phase and superimpose it onto the original phase map: based on the diffraction equation of the phase spatial light modulator imaging distribution. It can be seen that, with The unit is 0, where the zero-order diffraction image is located at 0, and the first-order diffraction image is located at 0. Location; based on the blazing conditions of the blazed grating When the superposition period in the original phase diagram is When the blazing grating is used, the diffraction image is shifted. It deviates to the center position of the 0th and 1st order light spots; in the horizontal and vertical superposition After a periodic blazed grating, the diffraction image is shifted both longitudinally and laterally. ;in, The pixel size of the phase spatial light modulator. For diffraction angle, For diffraction orders, The wavelength of the light source, For the blazed grating period, For the shining corner;

[0020] Calculate the phase of the diverging spherical wave and superimpose it onto the original phase diagram: using the spherical wave calculation formula Calculate the phase of the spherical wave and superimpose it onto the phase diagram; where, pixel coordinates The phase value of the spherical wave at that location, Let be the radius of the spherical wave.

[0021] In some embodiments of the present invention, the method further includes:

[0022] Based on the refraction distance of the off-axis diffraction image Determine the exit angle of the wedge prism ; The size of the off-axis diffraction image;

[0023] According to the angle of departure Determine the apex angle of the wedge prism ;in The refractive index of the wedge prism. is the refractive index of air.

[0024] In some embodiments of the present invention, the method further includes:

[0025] Based on the combined focal length formula The offset between the focal position of the zeroth-order diffracted beam and the focal position of the off-axis diffracted image is obtained. .

[0026] A laser projection display system is proposed, comprising:

[0027] A laser light source is used to provide a beam of illumination;

[0028] A phase spatial light modulator is used to modulate the phase of an illumination beam.

[0029] Digital micromirror devices are used to modulate phase-modulated illumination beams to form display images;

[0030] A lens is positioned on the light-emitting side of the phase spatial light modulator;

[0031] A wedge-shaped prism array, with an opaque area at the center, is positioned at a distance from the light-emitting side of the lens. Place; among them, The focal length of the lens;

[0032] The image processing module, upon receiving the image signal input, calculates the original phase map of the target image; adds the blazed grating phase and spherical wave phase to the original phase map; and loads the final phase map into the phase spatial light modulator.

[0033] Among them, the blazed grating phase is used to make the illumination beam modulated by the phase spatial light modulator so that the diffraction image propagates off-axis; the spherical wave phase is used to make the focal position of the off-axis diffraction image offset from the focal position of the zero-order diffraction light in depth; the zero-order diffraction light is focused by the lens to the opaque center of the wedge prism array and filtered out, and the off-axis diffraction image is refracted to the plane of the digital micromirror device for imaging by the wedge prism array.

[0034] In some embodiments of the present invention, the wedge prism array includes four wedge prisms assembled on a fixture in a centrally symmetrical four-quadrant structure, with the center of the fixture configured as an opaque region to filter out zero-order diffraction light; the off-axis diffraction image is folded onto the axis by the four diffraction prisms and imaged on the plane of the digital micromirror device.

[0035] In some embodiments of the present invention, the image processing module includes a blazed grating phase calculation unit and a spherical wave phase calculation unit;

[0036] The blazed grating phase calculation unit calculates the phase based on the diffraction equation of the phase spatial light modulator imaging distribution. It can be seen that, with The unit is 0, where the zero-order diffraction image is located at 0, and the first-order diffraction image is located at 0. Location; based on the blazing conditions of the blazed grating When the superposition period in the original phase diagram is When the blazing grating is used, the diffraction image is shifted. It deviates to the center position of the 0th and 1st order light spots; in the horizontal and vertical superposition After a periodic blazed grating, the diffraction image is shifted both longitudinally and laterally. ;in, The pixel size of the phase spatial light modulator. For diffraction angle, For diffraction orders, The wavelength of the light source, For the blazed grating period, For the shining corner;

[0037] The spherical wave phase calculation unit uses the spherical wave calculation formula. Calculate the phase of the spherical wave and superimpose it onto the phase diagram; where, pixel coordinates The phase value of the spherical wave at that location, Let be the radius of the spherical wave.

[0038] In some embodiments of the present invention, when the period of the blazed grating When the diffraction image deviates to the center position of the 0th and 1st order light spots, the wedge prism needs to be in place. The distance will shift the diffraction image along a 45-degree direction. The exit angle of the off-axis diffraction image after passing through the wedge prism is... ;in, The size of the diffraction image;

[0039] Then the apex angle of the wedge prism With the angle of light emission The relationship is:

[0040] ,in The refractive index of the wedge prism. is the refractive index of air.

[0041] In some embodiments of the present invention, according to the combined focal length formula The digital micromirror device is placed behind the wedge prism array. Place.

[0042] In some embodiments of the present invention, the wedge prism is a right-angled triangular prism cut at 45 degrees to the left and right of the middle of a standard wedge prism;

[0043] Four right-angled triangular prisms are placed in fixed frames in four quadrants with their right-angled edges as vertices to form a wedge-shaped prism array.

[0044] Compared with the prior art, the advantages and positive effects of the present invention are as follows: The laser projection display method and laser projection display system proposed in this invention have a lens set at the rear end of the phase spatial light modulator, and a wedge prism array set on the light-emitting side of the lens. A blazed grating phase and a spherical wave phase are superimposed on the original phase map obtained based on the image signal. The blazed grating phase is used to allow the diffraction image to propagate off-axis, while the zero-order diffraction light is unaffected and still propagates on the optical axis. The spherical wave phase causes the focal position of the off-axis diffraction image to be offset from the focal position of the zero-order diffraction image in depth. The final phase map is modulated by the phase spatial light modulator to form an off-axis diffraction image and a non-off-axis zero-order diffraction light. The zero-order diffraction light is focused by the lens at the opaque center of the wedge prism array and filtered out. The off-axis diffraction image is refracted back onto the axis by the wedge prism array and imaged on the plane of the digital micromirror device. The image displayed by the digital micromirror device is projected onto the projection screen through the projection lens to complete the laser projection display. The design of this invention uses a wedge prism array as a zero-order diffraction light device to address the problem of zero-order diffraction spots affecting image quality in laser projection display systems due to the use of spatial phase light modulators to modulate the laser source. Furthermore, by integrating multi-order diffraction images, the peak brightness of the backlight is improved, further expanding the contrast range of the laser projection display system.

[0045] Other features and advantages of the present invention will become clearer after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 The optical processing architecture of existing laser projection display systems;

[0048] Figure 2 The optical processing architecture for existing HDR laser projection display systems;

[0049] Figure 3 This invention presents the optical processing architecture for a laser projection display system.

[0050] Figure 4 This is a schematic diagram of the zero-order diffraction optical path in the laser projection display system proposed in this invention;

[0051] Figure 5 This is a schematic diagram of the diffraction image without any processing.

[0052] Figure 6 This is the distribution of the diffraction image on the plane of the wedge prism array in the design of this invention;

[0053] Figure 7 This relates to the refractive principle of the wedge prism in the design of this invention;

[0054] Figure 8 This is a schematic diagram of a single wedge-shaped prism structure.

[0055] Figure 9 This invention uses a single wedge prism to generate four off-axis diffraction images (producing structural interference shielding).

[0056] Figure 10 This is a schematic diagram of the cutting of a single wedge prism in the design of this invention;

[0057] Figure 11 This is an assembly diagram of the wedge prism array in the design of this invention;

[0058] Figure 12 This is a schematic diagram of the wedge prism array used in the design of this invention to filter out zero-order diffraction light;

[0059] Figure 13 This is a schematic diagram of phase map superposition in the design of this invention;

[0060] Figure 14 This is a schematic diagram illustrating the calculation of the original phase map using the GS algorithm in the design of this invention;

[0061] Figure 15This is a schematic diagram of the light intensity distribution in the wedge prism array plane of the final phase diagram in this invention;

[0062] Figure 16 This is a schematic diagram of the light intensity distribution on the plane of the digital micromirror device in the design of this invention;

[0063] Figure 17 This invention presents the system architecture of the laser projection display system.

[0064] Figure 18 This is a system timing diagram of the laser projection display system of the present invention;

[0065] Figure 19 This is a schematic diagram of the laser projection display method proposed in this invention. Detailed Implementation

[0066] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] This invention aims to propose a laser projection display system and its display method, eliminating the zero-order diffracted beam that cannot be modulated (due to manufacturing defects in the PLM, such as pixel spacing and surface encapsulation glass, some light rays are not diffracted after passing through the PLM), and retaining the modulable light (i.e., the diffracted DMD illumination field) distributed on the DMD plane for imaging. Specifically, as shown... Figure 3 As shown, the system consists of a laser source 1, a beam shaping device 2, a phase spatial light modulator (PLM) 3, a lens 4, a wedge prism array 5, a digital micromirror device (DMD) 6, a projection lens 7, and a projection screen 8.

[0068] Laser source 1 provides an illumination beam. Beam shaping device 2 shapes and homogenizes the illumination beam. Phase spatial light modulator 3 modulates the phase of the illumination beam, changing the direction of light propagation and causing different light waves to interfere in space, thereby achieving beam shaping. Lens 4 is placed behind phase spatial light modulator 3 at a distance... The wedge prism array 5 is placed behind the lens 4 at a distance of [location missing]. Among them This is the focal length of lens 4. The digital micromirror device 6 is placed behind the wedge prism array 5 at a distance... Place.

[0069] In this invention, the illumination beam emitted by the laser source 1 is shaped by the beam shaping device 2, and then, after being acted upon by the phase spatial light modulator 3, generates multiple diffraction images propagating off the optical axis and zero-order diffraction light propagating on the optical axis. The zero-order diffraction light is focused by the lens 4 onto the opaque center of the wedge prism array 5 and filtered out. The multiple off-axis diffraction images are then refracted back onto the axis by the wedge prism array 5, thus illuminating the digital micromirror device 6. The image content displayed by the digital micromirror device 6 is projected onto the projection screen 8 through the projection lens 7, completing the laser projection display. This design structure eliminates the influence of zero-order diffraction light on diffraction, while integrating a larger diffraction area, further expanding the brightness range of the laser projection display system, and avoiding the problem of uneven brightness.

[0070] Specifically, such as Figure 4 As shown, in the laser projection display system of the present invention, the focal length is Lens 4 is placed behind the PLM at a distance At this point, the unmoduloable zero-order diffracted light is focused onto the opaque center of the wedge prism array 5 plane, thus being filtered out by the opaque center; the DMD illumination field, diffracted from the moduloable light, is distributed on the DMD plane for imaging. Based on this design concept, in the laser projection display system of the present invention, it is necessary to ensure that the unmoduloable zero-order diffracted light still propagates on the axis, while the PLM-modulated DMD illumination field propagates off-axis, and the imaging plane is at the DMD.

[0071] To achieve the above concept, the present invention employs the following technical means: (1) Adding a blazed grating phase to the PLM phase diagram to allow the diffraction image to propagate away from the optical axis (the zero-order diffracted light, as an unmodulated part, still propagates along the optical axis). (2) Superimposing the phase of a diverging spherical wave on the PLM phase diagram to allow the focal position of the off-axis diffraction image to be offset in depth from the zero-order diffracted light. (3) The zero-order diffracted light is filtered out by the opaque center of the wedge prism array 5 located on the focusing plane of the zero-order diffracted light, and the off-axis diffracted image is focused by the wedge prism. The propagation distance is then reflected back onto the optical axis.

[0072] In this embodiment of the invention, four off-axis diffraction images are generated by adding a blazed grating phase to the phase map of the PLM, forming a pattern on the plane of the wedge prism array 5. Figure 6 The distribution shown is described below. The following explains how to generate such a distribution. Figure 6 The four diffraction patterns shown are derived in detail.

[0073] In a PLM optical system containing lenses, the phase hologram output by the GS is loaded into the PLM, and the distribution of the diffraction-reconstructed image is as follows: Figure 5 As shown, from the diffraction equation ( , For PLM pixel size, For diffraction angle, For diffraction orders, As can be seen from the wavelength of the light source, The unit is 0, where the zero-order diffraction image is located at 0, and the first-order diffraction image is located at 0. Place.

[0074] According to the blazing conditions of the blazed grating ( For the blazed grating period, For the shining corner, (where the wavelength is the light source), and the superposition period in the phase diagram is... When using a blazed grating, the diffraction image can be moved. That is, it is offset to the center position of the 0th and 1st order light spots.

[0075] Overlaying horizontally and vertically After a periodic blazed grating, the diffraction image is shifted both longitudinally and laterally. The distribution is as follows Figure 6 The four diffraction images shown are centered at ( ). , ), ( , ), ( , ), ( , ) place.

[0076] According to the theory of diffraction imaging, the size of the image is calculated by the following formula (1):

[0077] (1)

[0078] in, The wavelength of the illumination light, is the pixel size of the phase spatial light modulator.

[0079] Then the x and y coordinates of the four diffraction images are all 1. .

[0080] Therefore, by Figure 4 and Figure 6 It can be seen that, in the design of this invention, the wedge prism array 5 needs to achieve the following function: in The distance will shift the diffraction image along a 45-degree direction. , combined Figure 6 and Figure 7 As shown, to make the diffraction image translate along a 45-degree direction after passing through the wedge prism The exit angle should be .

[0081] To ensure that the exit angle of the light rays after passing through the wedge prism satisfies Combining such Figure 7 The refractive principle of the wedge prism shown can be derived from Snell's law, and the apex angle of the wedge prism can be obtained from the following equation (2). With the angle of light emission Relationship:

[0082] (2)

[0083] in The refractive index of the wedge prism. is the refractive index of air.

[0084] Because the diffraction pattern is shifted at a 45-degree angle, it is necessary to... Figure 8 The wedge prism shown is applied after being rotated 45 degrees to avoid interference and obstruction between structural components (such as...). Figure 9 As shown), in the actual design, a right-angled triangular prism is cut out at a 45-degree angle from the middle of the wedge prism. The four right-angled triangular prisms are placed in the four quadrants of the fixing frame with the right-angled edge as the vertex, forming a wedge prism array 5, as shown. Figure 11 As shown, four wedge prisms are assembled on a frame in a centrally symmetrical manner, with all right angles pointing towards the center of the frame. The center of the frame is designed to be opaque to block the passage of zero-order diffracted light. The off-axis diffraction image after filtering out the zero-order diffracted light is as follows: Figure 12 As shown.

[0085] According to the above design, the zero-order diffracted light is filtered out at the opaque center of the wedge prism array 5, and the DMD illumination field modulated by PLM propagates off-axis. The imaging surface is separated from the zero-order diffracted light focusing surface in depth, and the imaging surface is located at the DMD.

[0086] As explained in the aforementioned optical design methods, to achieve separation of the zero-order diffracted light and the diffracted image, and to ensure that the diffracted image propagates off-axis to the DMD plane for imaging, it is necessary to add the blazed grating phase and the diverging spherical wave phase to the PLM phase diagram, such as... Figure 13 As shown.

[0087] Specifically, such as Figure 19 As shown: (1) The phase map of the target image is calculated using the GS (Gerchberg-Saxton) algorithm.

[0088] First, the initial amplitude of the phase plane is... Set to 1, initial phase Random; based on the diffraction formula, the phase of the image plane is obtained. and amplitude distribution Only the phase information of the image plane is retained, and the amplitude is set to the amplitude of the target image. Based on the pseudo-diffraction formula, the amplitude and phase of the returned phase plane are obtained, and then the amplitude of the phase plane is... Set to 1 to preserve phase information. Repeat the diffraction and inverse diffraction between the phase plane and the image plane as described above until the error limit is met or the maximum number of iterations is reached. The overall flow of the GS algorithm is as follows: Figure 14 As shown.

[0089] (2) Calculate the phase of the blazed grating and superimpose it onto the original phase map.

[0090] Equation (3) is the grating equation for the PLM imaging distribution, and equation (4) is the blazing condition for the blazed grating:

[0091] (3)

[0092] (4)

[0093] in, For PLM pixel size, For diffraction angle, For diffraction orders, The wavelength of the light source, For the blazed grating period, For the shining corner.

[0094] When the period of the blazing grating At that time, the shining corner This means completing the off-axis processing of the diffraction image.

[0095] (3) Calculate the phase of the diverging spherical wave and superimpose it onto the original phase diagram.

[0096] Equation (5) is the formula for calculating divergent spherical waves:

[0097] (5)

[0098] in, coordinates The phase value of the spherical wave at that location, Let be the radius of the spherical wave.

[0099] According to the combined focal length formula of equation (6):

[0100] (6)

[0101] It can be determined that the DMD should be placed behind lens 4. Therefore .

[0102] (4) Load the final phase map into the phase space light modulator.

[0103] The final phase distribution of the PLM was obtained through (1), (2), and (3) above. This final phase distribution was applied to the PLM to separate the diffraction image from the zero-order diffraction light. The zero-order diffraction light was focused by lens 4 to the opaque center of the wedge prism array 5 and filtered out. The focusing position of the off-axis diffraction image was offset in depth from that of the wedge prism array 5. The wedge prism array 5 at a distance It is flipped onto the axis, thus imaging in the DMD plane. (Comparison) Figure 15 (Wedge prism array plane) and Figure 16 As can be seen from the DMD plane, this invention achieves the elimination of zero-order diffraction light and ensures the uniformity and contrast of the image.

[0104] When modulating laser sources of different wavelengths, it can be seen from equations (1) and (2) that the wedge prism apex angle of the wedge prism array 5 is... The requirements also differ. Taking 450nm, 532nm, and 650nm three-primary-color laser sources as examples, and using H-K9L glass as an example, the required wedge prism apex angle... The angles are 9.54º, 11.20º, and 13.49º respectively. Therefore, the apex angle of the wedge prism needs to be modified synchronously with the illumination of different colored laser light sources. This can be achieved by rotating three sets of wedge prism arrays or using liquid wedge prism arrays.

[0105] The laser projection display system proposed in this invention, such as Figure 17 As shown, the system includes an image processing module, a PLM driver module, a wedge prism driver module, a DMD driver module, and a light source driver module. After receiving the image signal input, the image processing module calculates the phase distribution of the PLM according to the aforementioned algorithm and transmits it to the PLM. The image processing module also outputs the image signal from the DMD, as well as timing synchronization signals for the RGB laser light source, PLM, wedge prism array angle, and DMD. When the RGB laser light source is lit, it illuminates the PLM. The PLM modulates the laser light source, dividing it into an off-axis diffraction image and a zero-order diffraction beam still on-axis. The zero-order diffraction beam is focused by lens 4 onto the opaque center of the wedge prism array 5 and filtered out. The off-axis diffraction image is then refracted by the wedge prism array 5 onto the DMD plane, where the DMD displays details to complete the image display. The timing synchronization signal is as follows: Figure 18 As shown.

[0106] It should be noted that, in the specific implementation process, the above-mentioned control part can be implemented by a hardware processor executing computer-executable instructions in software form stored in memory, which will not be elaborated here. The programs corresponding to the actions performed by the above control circuit can all be stored in the computer-readable storage medium of the system in software form, so that the processor can call and execute the operations corresponding to the above modules.

[0107] The computer-readable storage media mentioned above may include volatile memory, such as random access memory; may also include non-volatile memory, such as read-only memory, flash memory, hard disk or solid-state drive; and may also include combinations of the above types of memory.

[0108] The term "processor" as mentioned above can also refer to a collective of multiple processing elements. For example, a processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor, and it can also be a special-purpose processor.

[0109] It should be noted that the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A laser projection display method, applied in a laser projection display system, the laser projection display system comprising: A laser light source is used to provide a beam of illumination; A phase spatial light modulator is used to modulate the phase of an illumination beam. Digital micromirror devices are used to modulate phase-modulated illumination beams to form display images; A lens is positioned on the light-emitting side of the phase spatial light modulator; A wedge-shaped prism array, with an opaque area at the center, is positioned at a distance from the light-emitting side of the lens. Place; among them, The focal length of the lens; The method is characterized by comprising: Calculate the original phase map of the target image; Add a blazed grating phase and a spherical wave phase to the original phase diagram; the blazed grating phase is used to make the diffraction image propagate off-axis after the illumination beam is modulated by the phase spatial light modulator; the spherical wave phase is used to make the focal position of the off-axis diffraction image offset from the focal position of the zeroth order diffraction beam in depth. The final phase map is loaded into the phase spatial light modulator; in which the zeroth order diffracted light is focused by a lens onto the opaque center of the wedge prism array and filtered out, and the off-axis diffracted image is refracted to the plane of the digital micromirror device for imaging by the wedge prism array.

2. The laser projection display method according to claim 1, characterized in that, Add blazed grating phase and spherical wave phase to the phase map, specifically including: The GS algorithm is used to calculate the phase map of the target image; Calculate the blazed grating phase and superimpose it onto the original phase map: based on the diffraction equation of the phase spatial light modulator imaging distribution. It can be seen that, with The unit is 0, where the zero-order diffraction image is located at 0, and the first-order diffraction image is located at 0. Location; based on the blaze conditions of the blaze grating When the superposition period in the original phase diagram is When the blazing grating is used, the diffraction image is shifted. It is offset to the center position of the 0th and 1st order light spots; in the horizontal and vertical superposition After a periodic blazed grating, the diffraction image is shifted both longitudinally and laterally. ;in, The pixel size of the phase spatial light modulator. For diffraction angle, For diffraction orders, The wavelength of the light source, For the blazed grating period, For the shining corner; Calculate the phase of the diverging spherical wave and superimpose it onto the original phase diagram: using the spherical wave calculation formula Calculate the phase of the spherical wave and superimpose it onto the phase diagram; where, pixel coordinates The phase value of the spherical wave at that location, Let be the radius of the spherical wave.

3. The laser projection display method according to claim 2, characterized in that, The method further includes: Based on the refraction distance of the off-axis diffraction image Determine the exit angle of the wedge prism ; The size of the off-axis diffraction image; According to the angle of departure Determine the apex angle of the wedge prism ;in The refractive index of the wedge prism. is the refractive index of air.

4. The laser projection display method according to claim 3, characterized in that, The method further includes: Based on the combined focal length formula The offset between the focal position of the zeroth-order diffracted beam and the focal position of the off-axis diffracted image is obtained. .

5. A laser projection display system, comprising: A laser light source is used to provide a beam of illumination; A phase spatial light modulator is used to modulate the phase of an illumination beam. Digital micromirror devices are used to modulate phase-modulated illumination beams to form display images; The system is characterized in that it further includes: A lens is positioned on the light-emitting side of the phase spatial light modulator; A wedge-shaped prism array, with an opaque area at the center, is positioned at a distance from the light-emitting side of the lens. Place; among them, The focal length of the lens; The image processing module, upon receiving the image signal input, calculates the original phase map of the target image; adds the blazed grating phase and spherical wave phase to the original phase map; and loads the final phase map into the phase spatial light modulator. Among them, the blazed grating phase is used to make the illumination beam modulated by the phase spatial light modulator so that the diffraction image propagates off-axis; the spherical wave phase is used to make the focal position of the off-axis diffraction image offset from the focal position of the zero-order diffraction light in depth; the zero-order diffraction light is focused by the lens to the opaque center of the wedge prism array and filtered out, and the off-axis diffraction image is refracted to the plane of the digital micromirror device for imaging by the wedge prism array.

6. The laser projection display system according to claim 5, characterized in that, The wedge prism array includes four wedge prisms assembled on a fixture in a centrally symmetrical four-quadrant structure. The center of the fixture is configured as an opaque region to filter out zero-order diffraction light. The off-axis diffraction image is folded onto the axis by the four diffraction prisms and imaged on the plane of the digital micromirror device.

7. The laser projection display system according to claim 6, characterized in that, The image processing module includes a blazed grating phase calculation unit and a spherical wave phase calculation unit; The blazed grating phase calculation unit calculates the phase based on the diffraction equation of the phase spatial light modulator imaging distribution. It can be seen that, with The unit is 0, where the zero-order diffraction image is located at 0, and the first-order diffraction image is located at 0. Location; based on the blaze conditions of the blaze grating When the superposition period in the original phase diagram is When the blazing grating is used, the diffraction image is shifted. It is offset to the center position of the 0th and 1st order light spots; in the horizontal and vertical superposition After a periodic blazed grating, the diffraction image is shifted both longitudinally and laterally. ;in, The pixel size of the phase spatial light modulator. For diffraction angle, For diffraction orders, The wavelength of the light source, For the blazed grating period, For the shining corner; The spherical wave phase calculation unit uses the spherical wave calculation formula. Calculate the phase of the spherical wave and superimpose it onto the phase diagram; where, pixel coordinates The phase value of the spherical wave at that location, Let be the radius of the spherical wave.

8. The laser projection display system according to claim 7, characterized in that, When the period of the blazing grating When the diffraction image deviates to the center position of the 0th and 1st order light spots, the wedge prism needs to be in place. The distance will shift the diffraction image along a 45-degree direction. The exit angle of the off-axis diffraction image after passing through the wedge prism is... ;in, The size of the diffraction image; Then the apex angle of the wedge prism With the angle of light emission The relationship is: ,in The refractive index of the wedge prism. is the refractive index of air.

9. The laser projection display system according to claim 8, characterized in that, According to the combined focal length formula The digital micromirror device is placed behind the wedge prism array. Place.

10. The laser projection display system according to claim 7, characterized in that, The wedge prism is a right-angled triangular prism cut at 45 degrees to the left and right of the middle of a standard wedge prism. Four right-angled triangular prisms are placed in fixed frames in four quadrants with their right-angled edges as vertices to form a wedge-shaped prism array.

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