WO2021184923A1 - 一种激光投影装置 - Google Patents

一种激光投影装置 Download PDF

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Publication number
WO2021184923A1
WO2021184923A1 PCT/CN2020/142137 CN2020142137W WO2021184923A1 WO 2021184923 A1 WO2021184923 A1 WO 2021184923A1 CN 2020142137 W CN2020142137 W CN 2020142137W WO 2021184923 A1 WO2021184923 A1 WO 2021184923A1
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Prior art keywords
phase modulation
modulation
phase
pixel
laser
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French (fr)
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李士杰
王霖
贾坤
李屹
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Shenzhen Appotronics Corp Ltd
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Appotronics Corp Ltd
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2006—Lamp housings characterised by the light source
    • G03B21/2033—LED or laser light sources
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G02B27/1006—Beam splitting or combining systems for splitting or combining different wavelengths
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/206—Control of light source other than position or intensity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3102—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems

Definitions

  • This application relates to the field of laser display, and in particular to a laser projection device.
  • Laser projection display is more and more popular with audiences due to its advantages of high brightness and large color gamut.
  • laser projection is a coherent light source, which will produce speckle phenomenon, that is, the undulating granular pattern of light and dark, which affects the viewer's viewing experience.
  • methods such as wavelength division, rotational averaging, and time coherence reduction are used to reduce speckle contrast.
  • the wavelength division method has strict requirements on the wavelength selection of the light source, which will greatly increase the cost of the product; the rotating elements used in the rotational averaging method are common It is large in size and needs to be driven by a motor, which leads to an increase in the size of the projector, which is prone to noise; reducing time coherence and using materials such as volume diffusion will reduce the light efficiency of the projector.
  • This application provides a laser projection device to solve the problems in the prior art.
  • a technical solution adopted in this application provides a laser projection device, characterized in that the laser projection device at least includes a laser light source, a light combining device, a collimating device, at least one phase modulation device and a spatial light Modulation device, the laser light generated by the laser light source is irradiated to the phase modulation device through the light combining device and the collimating system.
  • the phase modulation device is used for phase modulation of the laser
  • the spatial light modulation device is used for the optical signal space of the phase modulated laser.
  • Distributed modulation wherein one spatial light modulation pixel is covered by at least two phase modulation pixels.
  • the present application adds a phase modulation device to phase-modulate the laser beam generated by the laser light source, and at the same time one spatial light modulation pixel is covered by at least two phase modulation pixels, so that the spatial light
  • the same pixel of the modulation device is affected by the phases of the pixels of multiple phase modulation devices to achieve an average light intensity distribution formed on the retina and reduce the speckle contrast.
  • Only add the phase modulation device do not need to consider the influence of the light source wavelength, and will not affect the light efficiency of the projector.
  • Commonly used phase modulation devices are small-scale modulation elements such as transmissive liquid crystal, LCOS or GLV, which can reduce the production cost without the need to increase the volume of the laser projection device.
  • Fig. 1 is a schematic structural diagram of a first embodiment of a laser projection device according to the present application
  • Figure 2 is the first structure of the positional relationship between spatial light modulation pixels and phase modulation pixels in Figure 1
  • Figure 3 is a second structure of the positional relationship between spatial light modulation pixels and phase modulation pixels in Figure 1
  • FIG. 4 is a schematic structural diagram of a second embodiment of a laser projection device according to the present application.
  • FIG. 5 is a schematic diagram of the voltage modulation result of the phase modulation device in FIG. 4;
  • Fig. 6 is a schematic structural diagram of a third embodiment of a laser projection device according to the present application.
  • Fig. 7 is the result of the positional relationship between the first phase modulation pixel and the second phase modulation pixel in Fig. 6
  • FIG. 1 is a schematic structural diagram of a first embodiment of a laser projection device according to the present application.
  • the laser projection device 1 includes a laser light source 10, a light combining device 20, a collimating device 30, at least one phase modulation device 40, a spatial light modulation device 50 and a projection lens 60.
  • the laser light source 10 is an RGB three-color laser, which generates a laser beam and irradiates the light combining device 20.
  • the laser beam includes a red laser, a blue laser, and a green laser.
  • the laser light source 10 may also be a single laser or dual lasers.
  • the laser beam is irradiated on the projection lens 60 through the light combining device 20 for light combining, the collimating device 30 for collimating, the phase modulation device 40 for phase modulation, and the spatial light modulation device 50 for light enhancement. 60 projection screen.
  • the phase modulation device 40 phase-modulates the laser light to obtain phase-modulated pixels.
  • the phase-modulated pixel is the pixel area where the laser light is phase-modulated by the phase modulation device 40 and imaged and displayed.
  • the spatial light modulation device 50 modulates the laser light by spatial distribution of the optical signal to obtain the phase modulation pixel.
  • the spatial light modulation pixel is a pixel area where the laser is imaged and displayed after the spatial distribution of the optical signal of the spatial light modulation device 50 is modulated. Without adding the phase modulation device 40 to perform phase modulation, the initial phase of the wavefront phase of the smallest image spot that can be distinguished by the human eye projected by the projection lens 60 is zero. In other words, the smallest image spot that can be distinguished by the human eye is a single spatial light pixel. After phase modulation is performed by the rough surface microstructure of the projection lens 60, the phase distribution before entering the human eye is The electric field vector is expressed as formula (1):
  • A is the amplitude of the electric field vector.
  • Equation (2) After the phase modulation of the eye, the minimum resolvable spot the electric field vector E '0 (x, y) is focused on the retina, as shown in Equation (2):
  • ⁇ is the wavelength of monochromatic light
  • f is the equivalent focal length of the human eye.
  • E f (u,v) is the sum of many vectors, not only related to the amplitude A of the electric field vector, but also related to the phase modulation of the light spot by the diffusion structure Related.
  • the human eye only responds to the electric field intensity I of light, and cannot sense the phase of light waves. Therefore, the phase factor before the integral number in formula (3) can be ignored, and the relational expression of electric field intensity I is shown in formula (4):
  • the final human eye's response to the light intensity or brightness of the smallest resolvable spot depends not only on the amplitude A of the light wave electric field, but also on the phase modulation of the surface microstructure on its wavefront Since the scattering microstructures of different areas of the projection screen are different, and the degree of phase modulation is different, the light intensity distribution I f (u, v) formed on the retina will fluctuate randomly.
  • the phase modulation device 40 is arranged before the spatial light modulation device 50, the minimum resolving spot is divided into two or more, that is, at least two phase modulation pixels divide a single spatial light modulation pixel into two or More copies, modulate its phase separately So that the phase distribution in the spot is as shown in formula (5):
  • P n (x, y) means that the minimum resolving spot is divided into N parts, and t is a different time. Bundle Incorporating into formula (4), we can get that I f (u,v) also changes with time. Therefore, during the integration time of the human eye , the superposition of different I f (u, v) can average the light intensity and play a role in reducing the speckle contrast C. An average of M mutually independent speckle patterns can reduce the speckle contrast C, and the degree of reduction is from 1 to
  • FIG. 2 is a first structural schematic diagram of the positional relationship between the spatial light modulation pixel and the phase modulation pixel in FIG. 1.
  • the phase modulation pixel performs partition processing on the spatial light modulation pixel to achieve the smallest resolving spot divided into two or more.
  • the size of a spatial light modulation pixel may be an integer multiple of a phase modulation pixel.
  • the size of a spatial light modulation pixel may be a second power multiple of a phase modulation pixel.
  • the phase modulation pixel divides the spatial light modulation pixel into 2 equal parts of the same size, and the ratio of the phase modulation pixel density to the spatial light modulation pixel density is 2:1.
  • one spatial light modulation pixel is covered by two phase modulation pixels; as shown in Figure 2(B), the phase modulation pixel divides the spatial light modulation pixel into 4 equal parts of the same size.
  • the ratio of modulation pixel density is 4:1.
  • one spatial light modulation pixel is covered by four phase modulation pixels; as shown in Figure 2(C), the phase modulation pixel divides the spatial light modulation pixel into 9 equal parts of the same size.
  • the ratio of modulation pixel density is 9:1. In other words, one spatial light modulation pixel is covered by only nine phase modulation pixels.
  • the phase modulation pixel divides the spatial light modulation pixel into n regions of the same size.
  • the ratio of the phase modulation pixel density to the spatial light modulation pixel density is n, and n is greater than 1, that is, a spatial light modulation pixel is Only n phase modulation pixels are covered.
  • FIG. 3 is a second structural schematic diagram of the positional relationship between the spatial light modulation pixel and the phase modulation pixel in FIG. 1.
  • the size of a single phase modulation pixel can be larger than that of a single spatial light modulation pixel.
  • the phase modulation pixel is misaligned to cover the spatial light modulation pixel, so that a single phase modulation pixel is misaligned to cover at least two spatial light modulation pixels.
  • the phase modulation pixels are misaligned to cover a single spatial light modulation pixel.
  • the smallest resolving spot is divided into n parts, that is, the spatial light modulation pixel is divided into n regions of different sizes, and the spatial light modulation pixel density is increased to make a single
  • the spatial light modulation pixel is affected by the phases of multiple phase modulation pixels, increasing the random phase change and reducing the speckle contrast.
  • FIG. 4 is a schematic structural diagram of a second embodiment of a laser projection device according to the present application.
  • the light combining device 20 includes a first dichroic mirror 21 and a second dichroic mirror 22.
  • the first dichroic mirror 21 is used to combine the green laser and blue laser light emitted by the laser light source 10
  • the second dichroic mirror 22 is used to combine the first dichroic mirror 21 and the second dichroic mirror 22.
  • the laser light outputted by the dichroic mirror 21 and the red laser light emitted by the laser light source 10 are combined.
  • the collimating device 30 includes a lens group 31, and the lens group 31 may be formed by a combination of a plurality of convex lenses or concave lenses.
  • the lens group 31 collimates the laser light output from the second dichroic mirror 22 so that the laser light can be uniformly irradiated on the phase modulation device 40.
  • the phase modulation device 40 is a phase modulation liquid crystal, and the phase modulation liquid crystal is a transmissive liquid crystal panel, which only changes the phase of the laser light without changing its polarization direction, and realizes the phase modulation of the laser light.
  • the phase adjustment capability of the phase modulation liquid crystal is related to its driving voltage.
  • the driving voltage of the phase modulation liquid crystal is 0V-5V.
  • the phase modulation device 40 may also be a phase modulation element such as LCOS or GLV.
  • the spatial light modulation device 50 is a digital micro-mirror (DMD chip), which is used to perform light-emphasis on the phase-modulated laser light.
  • the DMD chip is DLP Automotive DMD.
  • the resolution of the DMD chip is 864*480, which is smaller than the preset image display resolution.
  • the preset resolution may be 2K.
  • the resolution of the transmissive liquid crystal panel is 1920*1080, which ensures that a single spatial light modulation pixel is split into 4 parts of the same size by multiple phase modulation pixels, as shown in Figure 2(B). Every four adjacent phase modulation pixels in the phase modulation device 40 form a group, and the corresponding driving voltage changes with a time period.
  • FIG. 5 is a schematic diagram of the voltage modulation result of the phase modulation device in FIG. 4.
  • the four adjacent phase modulation pixels in the phase modulation device 40 are respectively LC1, LC2, LC3, and LC4, and the corresponding phase changes of LC1, LC2, LC3, and LC4 are with
  • the time period of LC1 drive voltage change is two frames
  • the time period of LC2 drive voltage change is one frame
  • the time period of LC3 drive voltage change is one-half frame
  • the time period of LC4 drive voltage change is One-third of the frame.
  • FIG. 6 is a schematic structural diagram of a third embodiment of a laser projection device according to the present application.
  • the laser projection device 1 further includes a first phase modulation device 41 and a second phase modulation device 42.
  • the first phase modulation device 41 is a phase modulation liquid crystal
  • the second phase modulation device 42 is a phase modulation LCOS.
  • the first phase modulation device 41 may also be a phase modulation element such as LCOS or GLV
  • the second phase modulation device 42 may also be a phase modulation element such as a phase modulation liquid crystal or a GLV.
  • the spatial light modulation device 50 is an LCOS spatial light modulation chip.
  • the second phase modulation device 42 is arranged between the lens group 31 and the first phase modulation device 41, and the first phase modulation device 41 and the second phase modulation device 42 are arranged in a staggered manner to make the first phase modulation pixel and the second phase modulation pixel Together, the spatial light modulation pixels are divided into 4 equal parts of the same size, and the smallest resolving spot is divided into four parts.
  • the phase modulation pixel density should be more than twice the spatial light modulation pixel density, that is, a single spatial light modulation pixel is covered by two phase modulation pixels.
  • the resolution of the spatial light modulation device 50 is greater than the preset resolution of image display, the resolution of the single-chip phase modulation device 40 is difficult to reach twice the resolution of the spatial light modulation device 50.
  • the resolution of the LCOS spatial light modulation chip is 1920*1080, and the resolution of the phase modulation liquid crystal and the phase modulation LCOS are both 480*320.
  • the phase modulation liquid crystal and the phase modulation LCOS are combined to realize the resolution of the phase modulation device 40 as space
  • the light modulator has more than twice the pixel density of 50.
  • FIG. 7 is a schematic structural diagram of the positional relationship between the first phase modulation pixel and the second phase modulation pixel in FIG. 6.
  • the first phase modulation pixel is a pixel area where the laser light is phase-modulated by the first phase modulation device 41
  • the second phase modulation pixel is a pixel area where the laser light is phase-modulated by the second phase modulation device 42.
  • the positions are shifted by half the pixel size along the first direction I and the second direction II respectively, so that the first phase modulation pixel and the second phase modulation pixel overlap
  • the number of virtual phase modulation pixels with different phase distributions in the area is increased by four times, that is, the resolution of the phase modulation device 40 is 1920*1280.
  • the driving voltages corresponding to the four virtual phase modulation pixels vary with the time period, and the time periods of the driving voltage of the different virtual phase modulation pixels are different. Change rapidly over time, at different moments They are independent of each other, so that the brightness of the spatial light modulation pixels corresponding to the four virtual phase modulation pixels adjacent to the overlapping area can be averaged within the integration time of the human eye to achieve the effect of eliminating speckle.

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Abstract

一种激光投影装置（1），激光投影装置（1）至少包括激光光源（10）、合光装置（20）、准直装置（30）、至少一个相位调制装置（40）和空间光调制装置（50），激光光源（10）产生的激光经过合光装置（20）和准直装置（20）照射到相位调制装置（40）上，相位调制装置（40）用于对激光进行相位调制，空间光调制装置（50）用于对相位调制后的激光进行光信号空间分布的调制；其中，一个空间光调制像素被至少两个相位调制像素覆盖。增加相位调制装置（40），对激光光源（10）产生的激光光束进行相位调制，同时一个空间光调制像素被至少两个相位调制像素覆盖，使空间光调制装置（50）同一像素受多个相位调制装置（40）像素相位的影响，实现平均光强，降低散斑对比度。

Description

一种激光投影装置 技术领域
本申请涉及激光显示领域，特别是涉及一种激光投影装置。
背景技术
激光投影显示凭借其高亮度、大色域等优势，越来越受到观众欢迎。但是激光投影是相干光源，会产生散斑现象，即明暗起伏的颗粒状图案，影响观众的观看体验。现有技术中使用分波长、转动平均、降低时间相干性等方法降低散斑对比度，但是分波长法对光源的波长选择要求比较苛刻，会大大提高产品成本；转动平均法中使用的转动元件普遍体积较大，并且需要电机驱动，导致投影机体积增大，容易产生噪音；降低时间相干性使用体扩散等材料，会降低投影机的光效。
发明内容
本申请提供一种激光投影装置，以解决现有技术中的问题。
为解决上述技术问题，本申请采用的一个技术方案书：提供一种激光投影装置，其特征在于，激光投影装置至少包括激光光源、合光装置、准直装置、至少一个相位调制装置和空间光调制装置，激光光源产生的激光经过合光装置和准直系统照射到相位调制装置上，相位调制装置用于对激光进行相位调制，空间光调制装置用于对相位调制后的激光进行光信号空间分布调制；其中，一个空间光调制像素被至少两个相位调制像素覆盖。
本申请的有益效果是：区别于现有技术，本申请增加相位调制装置，对激光光源产生的激光光束进行相位调制，同时一个空间光调制像素被至少两个相位调制像素覆盖，以使空间光调制装置同一像素受多个相位调制装置像素相位的影响，实现平均在视网膜上形成的光强分布，降低 散斑对比度。只增加相位调制装置，不需要考虑光源波长的影响，同时不会影响投影机的光效。常用相位调制装置为透射式液晶、LCOS或者GLV等小型调制元件，无需额外增加激光投影装置的体积，能够降低生产成本。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本申请激光投影装置第一实施例的结构示意图；
图2是图1中空间光调制像素与相位调制像素位置关系的第一结构
示意图；
图3是图1中空间光调制像素与相位调制像素位置关系的第二结构
示意图；
图4是本申请激光投影装置第二实施例的结构示意图；
图5是图4中相位调制装置电压调制的结果示意图；
图6是本申请激光投影装置第三实施例的结构示意图；
图7是图6中第一相位调制像素与第二相位调制像素位置关系的结
构示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性的劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
为使本领域的技术人员更好地理解本申请的技术方案，下面结合附图和具体实施方式对发明所提供的激光投影装置做进一步详细描述。
请参阅图1，图1是本申请激光投影装置第一实施例的结构示意图。 激光投影装置1包括激光光源10、合光装置20、准直装置30、至少一个相位调制装置40、空间光调制装置50和投影镜头60。
激光光源10为RGB三色激光，产生激光光束照射于合光装置20上，激光光束包括红激光、蓝激光和绿激光。可选地，激光光源10还可以为单激光或双激光等。激光光束经合光装置20进行合光作用、准直装置30进行准直作用、相位调制装置40进行相位调制以及空间光调制装置50进行光强调制后，照射于投影镜头60上，通过投影镜头60投射画面。
相位调制装置40对激光进行相位调制后获得相位调制像素，相位调制像素为激光经相位调制装置40相位调制后成像显示的像素区域，空间光调制装置50对激光经进行光信号空间分布调制后获得空间光调制像素，空间光调制像素为激光经空间光调制装置50光信号空间分布调制后成像显示的像素区域。在不增加相位调制装置40进行相位调制的情况下，通过投影镜头60投射出的人眼可分辨的最小画面光斑的波前相位最初相位均为0。也就是说，人眼可分辨的最小画面光斑为单个空间光像素。经过投影镜头60粗糙表面微结构进行相位调制后，在进入人眼之前的相位分布为
Figure PCTCN2020142137-appb-000001
其电场矢量表达如公式(1)：
Figure PCTCN2020142137-appb-000002
其中，A为电场矢量的振幅。
经过眼睛的相位调制后，该最小可分辨光斑的电场矢量E' 0(x,y)聚焦到视网膜上，如公式(2)所示：
Figure PCTCN2020142137-appb-000003
其中
Figure PCTCN2020142137-appb-000004
为眼睛对光波前的相位调制。
在视网膜平面上(u，v平面)，根据标量衍射理论，电场矢量分布为E f(u,v)，定义如公式(3)所示：
Figure PCTCN2020142137-appb-000005
其中λ为单色光波长，f为人眼等效焦距。E f(u,v)是众多矢量的和，不仅和电场矢量的振幅A有关，还和扩散结构对光斑的相位调制
Figure PCTCN2020142137-appb-000006
相关。人眼只对光的电场强度I有相应，而无法感应光波相位，所以公式(3)中积分号前的相位因子可以被忽略，从而得到电场强度I的关系式如公式(4)所示：
Figure PCTCN2020142137-appb-000007
从公式(4)可以看出，最终人眼对该最小可分辨光斑的光强或亮度响应，不仅依赖于光波电场的振幅A，还依赖于表面微结构对其波前的相位调制
Figure PCTCN2020142137-appb-000008
由于投影画面不同区域的散射微结构不同，相位调制程度不同，所以在视网膜上形成的光强分布I f(u,v)会有随机涨落。
此时，如果将相位调制装置40设置于空间光调制装置50之前，将最小分辨光斑分成两份或更多份，也就是说，至少两个相位调制像素将单个空间光调制像素分成两份或更多份，分别调制其相位
Figure PCTCN2020142137-appb-000009
以使光斑内相位分布如公式(5)所示：
Figure PCTCN2020142137-appb-000010
其中P n(x,y)表示把最小分辨光斑分为N份，t为不同时刻。把
Figure PCTCN2020142137-appb-000011
带入公式(4)中，可以得到I f(u,v)也随时间变化。从而，在人眼积分时间内，不同的I f(u,v)的叠加，可以平均光强，起到降低散斑对比度C的作用。平均M个互相独立的散斑图案可以降低散斑对比度C，降低程度是从1到
Figure PCTCN2020142137-appb-000012
进一步参阅图2，图2是图1中空间光调制像素与相位调制像素位置关系的第一结构示意图。如图2所示，相位调制像素将空间光调制像素进行分区处理，实现将最小分辨光斑分成两份或更多份。可选地，一个空间光调制像素的大小可以为一个相位调制像素的整数倍。优选地，一个空间光调制像素的大小可以为一个相位调制像素的二次幂倍。
如图2(A)所示，相位调制像素将空间光调制像素分割为大小相同的2等份，相位调制像素密度与空间光调制像素密度之比为2：1。也就是说，一个空间光调制像素被两个相位调制像素覆盖；如图2(B)所 示，相位调制像素将空间光调制像素分割为大小相同的4等份，相位调制像素密度与空间光调制像素密度之比为4：1。也就是说，一个空间光调制像素被四个相位调制像素覆盖；如图2(C)所示，相位调制像素将空间光调制像素分割为大小相同的9等份，相位调制像素密度与空间光调制像素密度之比为9：1。也就是说，一个空间光调制像素被就九个相位调制像素覆盖。
如图2所示，相位调制像素将空间光调制像素分割为大小相同的n个区域，相位调制像素密度与空间光调制像素密度之比为n，且n大于1，即一个空间光调制像素被就n个相位调制像素覆盖。
进一步参阅图3，图3是是图1中空间光调制像素与相位调制像素位置关系的第二结构示意图。如图3所示，单个相位调制像素的大小可以大于单个空间光调制像素，此时相位调制像素错位覆盖空间光调制像素，以使单个相位调制像素错位覆盖至少两个空间光调制像素，同时多个相位调制像素错位覆盖单个空间光调制像素。
本实施例通过在空间光调制装置50之前设置相位调制装置40，将最小分辨光斑分为n份，即将空间光调制像素分割为大小不同的n个区域，增加空间光调制像素密度，以使单个空间光调制像素受多个相位调制像素相位的影响，增加随意相位变化，实现降低散斑对比度。
进一步参阅图4，图4是本申请激光投影装置第二实施例的结构示意图。合光装置20包括第一双色镜21和第二双色镜22，第一双色镜21用于将激光光源10发出的绿激光和蓝激光进行合光，第二双色镜22用于将经第一双色镜21合光后输出的激光与激光光源10发出的红激光进行合光。
准直装置30包括透镜组31，透镜组31可由多个凸透镜或凹透镜组合而成。透镜组31将第二双色镜22输出的激光进行准直，以使激光能够均匀照射在相位调制装置40上。
相位调制装置40为相位调制液晶，相位调制液晶为透射型液晶面板，只改变激光的相位，不改变其偏振方向，实现对激光的相位调制。其中，相位调制液晶的相位调节能力与其驱动电压相关。可选地，相位 调制液晶的驱动电压为0V-5V。可选地，相位调制装置40还可为LCOS或者GLV等相位调制元件。
空间光调制装置50为数字微反射镜(DMD芯片)，用于对相位调制后的激光进行光强调制。优选地，DMD芯片为DLP Automotive DMD。DMD芯片的分辨率为864*480，小于预设的图像显示的分辨率。可选地，预设的分辨率可为2K。透射型液晶面板的分辨率为1920*1080，保证单个空间光调制像素被多个相位调制像素拆分为大小相同的4份，如图2(B)所示。相位调制装置40中相邻的每四个相位调制像素为一组，并且对应的驱动电压随时间周期变化。
进一步参阅图5，图5是图4中相位调制装置电压调制的结果示意图。相位调制装置40中相邻的四个相位调制像素分别为LC1、LC2、LC3和LC4，LC1、LC2、LC3和LC4对应的相位变化为
Figure PCTCN2020142137-appb-000013
和
Figure PCTCN2020142137-appb-000014
如图5所示，LC1驱动电压变化的时间周期为两帧，LC2驱动电压变化的时间周期为一帧，LC3驱动电压变化的时间周期为二分之一帧，LC4驱动电压变化的时间周期为三分之一帧。
随着时间t的变化，LC1、LC2、LC3和LC4的相位也不停地变化，以使LC1、LC2、LC3和LC4对应的单个空间光调制像素在一帧时间内不停地变化。也就是说，
Figure PCTCN2020142137-appb-000015
随时间快速变化，不同时刻的
Figure PCTCN2020142137-appb-000016
互相独立，使人眼积分时间内观看这一空间光调制像素的亮度被平均，进而实现消除散斑的效果。当随意相位变化越快时，散斑对比度降低程度越大。
请参阅图6，图6是本申请激光投影装置第三实施例的结构示意图。激光投影装置1进一步包括第一相位调制装置41和第二相位调制装置42，第一相位调制装置41为相位调制液晶，第二相位调制装置42为相位调制LCOS。可选地，第一相位调制装置41还可为LCOS或者GLV等相位调制元件，第二相位调制装置42还可为相位调制液晶或者GLV等相位调制元件。空间光调制装置50为LCOS空间光调制芯片。
第二相位调制装置42设置于透镜组31和第一相位调制装置41之间，第一相位调制装置41与第二相位调制装置42错位设置，以使第一 相位调制像素与第二相位调制像素共同将空间光调制像素分割为大小相同的4等分，实现将最小分辨光斑分成四份。
为了有效地降低散斑对比度，相位调制像素密度应为空间光调制像素密度的两倍以上，即单个空间光调制像素被两个相位调制像素覆盖。当空间光调制装置50的分辨率大于预设的图像显示的分辨率时，单片相位调制装置40的分辨率难以达到空间光调制装置50的分辨率的两倍。LCOS空间光调制芯片的分辨率为1920*1080，相位调制液晶与相位调制LCOS的分辨率均为480*320，将相位调制液晶与相位调制LCOS组合使用，实现相位调制装置40的分辨率为空间光调制器50像素密度的两倍以上。
进一步参阅图7，图7是图6中第一相位调制像素与第二相位调制像素位置关系的结构示意图。第一相位调制像素为激光经第一相位调制装置41相位调制后成像显示的像素区域，第二相位调制像素为激光经第二相位调制装置42相位调制后成像显示的像素区域。
当第一相位调制像素与第二相位调制像素对位时，分别沿着第一方向Ⅰ和第二方向Ⅱ错开一半像素大小的位置，以使第一相位调制像素与第二相位调制像素的重合区域拥有不同相位分布的虚拟相位调制像素数量增加为四倍，即相位调制装置40的分辨率为1920*1280。以重合区域内相邻的四个虚拟相位调制像素为一组，四个虚拟相位调制像素对应的驱动电压随时间周期变化，不同虚拟相位调制像素驱动电压的时间周期不同。
Figure PCTCN2020142137-appb-000017
随时间快速变化，不同时刻的
Figure PCTCN2020142137-appb-000018
互相独立，以使人眼积分时间内观看重合区域相邻的四个虚拟相位调制像素对应的空间光调制像素的亮度被平均，实现消除散斑的效果。
以上仅为本申请的实施例，并非因此限制本申请的专利范围，凡是利用本申请说明书及附图内容所作的等效结构或等效流程变换，或直接或间接运用在其他相关的技术领域，均同理包括在本申请的专利保护范围内。

Claims (10)

  1. 一种激光投影装置，其特征在于，所述激光投影装置至少包括激光光源、合光装置、准直装置、至少一个相位调制装置和空间光调制装置，所述激光光源产生的激光经过所述合光装置和所述准直系统照射到所述相位调制装置上，所述相位调制装置用于对所述激光进行相位调制，所述空间光调制装置用于对相位调制后的激光进行光信号空间分布调制；
    其中，一个空间光调制像素被至少两个相位调制像素覆盖。
  2. 根据权利要求1所述激光投影装置，其特征在于，所述相位调制像素为所述激光经所述相位调制装置相位调制后成像显示的像素区域，所述空间光调制像素为所述激光经所述空间光调制装置光信号空间分布调制后成像显示的像素区域，一个所述空间光调制像素的大小为一个所述相位调制像素的整数倍，一个所述空间光调制像素包含至少两个所述相位调制像素。
  3. 根据权利要求1所述激光投影装置，其特征在于，所述相位调制像素为所述激光经所述相位调制装置相位调制后成像显示的像素区域，所述空间光调制像素为所述激光经所述空间光调制装置光信号空间分布调制后成像显示的像素区域，一个所述空间光调制像素小于一个所述相位调制像素，一个所述相位调制像素错位覆盖至少两个所述空间光调制像素。
  4. 根据权利要求1所述激光投影装置，其特征在于，所述空间光调制装置的分辨率小于预设的图像显示的分辨率，所述至少一个相位调制装置为相位调制液晶。
  5. 根据权利要求4所述激光投影装置，其特征在于，所述激光光源用于产生红激光、蓝激光和绿激光；
    所述合光装置包括第一双色镜和第二双色镜，所述第一双色镜用于将所述绿激光和所述蓝激光进行合光，所述第二双色镜用于将所述第一双色镜输出的激光与所述红激光进行合光；
    所述准直装置包括透镜组，所述第二双色镜射出的激光通过所述透镜组进行所述相位调制液晶，所述相位调制液晶对所述激光的进行相位调制；
    所述空间光调制装置为数字微反射镜，用于对相位调制后的激光进行光信号空间分布调制。
  6. 根据权利要求5所述激光投影装置，其特征在于，所述空间光调制装置的分辨率大于或等于预设的图像显示的分辨率，所述至少一个相位调制装置还包括相位调制LCOS。
  7. 根据权利要求6所述激光投影装置，其特征在于，所述相位调制LCOS设置在所述透镜组和所述相位调制液晶之间，且所述相位调制LCOS的像素与所述相位调制液晶的像素错位设置。
  8. 根据权利要求4所述激光投影装置，其特征在于，所述相位调制液晶将四个相邻的像素划分成一组，所述四个相邻的像素对应的驱动电压随时间周期变化。
  9. 根据权利要求8所述激光投影装置，其特征在于，所述四个像素对应的驱动电压的时间周期不同。
  10. 根据权利要求8所述激光投影装置，其特征在于，每个所述相位调制像素的相位值满足以下公式：
    Figure PCTCN2020142137-appb-100001
    其中，P n(x,y)表示把最小分辨光斑分为N份，t为不同时刻，所述最小分辨光斑为单个所述空间光调制像素；
    将所述相位调制像素的相位值积分得到单个所述相位调制像素的电场强度：
    Figure PCTCN2020142137-appb-100002
    所述电场强度随时间变化，积分时间内多个所述电场强度叠加，平均所述积分时间内激光的电场强度。
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