CN113900328A - Long-distance projection device and method for penetrating scattering medium based on spatial light modulation device - Google Patents
Long-distance projection device and method for penetrating scattering medium based on spatial light modulation device Download PDFInfo
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- 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
- G03B21/142—Adjusting of projection optics
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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
- G03B21/2013—Plural light sources
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- 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
- G03B21/204—LED or laser light sources using secondary light emission, e.g. luminescence or fluorescence
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- 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
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- G—PHYSICS
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- 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
- G03B21/2066—Reflectors in illumination beam
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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
- G03B21/54—Accessories
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- G03B21/60—Projection screens characterised by the nature of the surface
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- 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
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- 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
- H04N9/3173—Constructional details thereof wherein the projection device is specially adapted for enhanced portability
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- 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]
- H04N9/3179—Video signal processing therefor
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Abstract
The invention provides a remote projection device and a remote projection method for penetrating scattering media based on a spatial light modulator, which can enable projection light to penetrate the scattering media and form images on a projection screen with high quality, wherein a light source, the spatial light modulator and a projection image head are sequentially arranged on a projection light path; the projection light path is connected with the control device; the control device is connected with a high-speed imaging detector which can collect imaging images from a projection screen, the current projection effect is evaluated by the imaging images collected by the high-speed imaging detector, and a projection light path is adjusted to optimize the imaging effect; the invention has the automatic feedback device and function, can automatically adjust the output power of laser light sources with different wavelengths and the modulation state of the spatial light modulation device according to the projection distance, the characteristics and the dynamic change of a scattering medium in a projection light path, realizes the real-time control of a projection image along with the change of the distance and the scattering medium, and adjusts and optimizes the light intensity and the wave band distribution of a projection light beam in real time, thereby ensuring the high-quality image projection.
Description
Technical Field
The invention relates to the technical field of projection, in particular to a penetrating and scattering medium long-distance projection device and method based on a spatial light modulation device.
Background
With the development of projection technology, the projection technology is applied to more and more occasions, the occasions where the projection is applied are more and more complex, and people are pursuing a method capable of realizing clear projection under the condition that the outdoor environment is interfered by severe weather conditions such as fog and haze. But it is difficult to achieve real-time control of the quality of the projected image due to the nature of the scattering medium. The existing projector is mainly applied in an indoor static scene, namely, the projector projects a picture to a fixed screen position and cannot perform corresponding self-adaptive adjustment along with the change of the screen position or the change of a projection environment. The method mainly has the following reasons that the existing projection technology has higher requirements on the environment of a projection light path, and cannot show a better projection effect in a complex environment, such as the condition that scattering media such as rain, fog and haze exist outdoors or the condition that artificial smoke exists indoors; on the other hand, the current projection technology is limited by the light intensity and the distance of a light source, and the light intensity is attenuated quickly when scattering media exist in a projection light path, so that long-distance imaging cannot be performed.
Disclosure of Invention
The invention provides a remote projection device and a remote projection method for penetrating scattering media based on a spatial light modulation device, which have automatic feedback devices and functions, can automatically adjust the output power of laser light sources with different wavelengths and the modulation state of the spatial light modulation device according to the projection distance, the characteristics and the dynamic change of the scattering media in a projection light path, realize the real-time control of projection images along with the change of the distance and the scattering media, and adjust and optimize the light intensity and the wave band distribution of projection light beams in real time, thereby ensuring the high-quality image projection.
The invention adopts the following technical scheme.
The remote projection device based on the spatial light modulation device and capable of penetrating the scattering medium can enable projection light to penetrate the scattering medium (11) and form images on a projection screen (12) in a high-quality mode, and a light source, the spatial light modulation device (9) and a projection image head (10) are sequentially arranged on a projection light path of the projection device; the projection light path is connected with the control device; the control device is connected with a high-speed imaging detector (13) capable of collecting imaging images from the projection screen, the current projection effect is evaluated through the imaging images collected by the high-speed imaging detector, and the projection light path is adjusted to optimize the imaging effect.
The control device is connected with the light source; the light source comprises a first laser light source (1), a second laser light source (2) and a third laser light source (3);
the first laser light source is a red laser light source with the central wavelength within the range of 615nm-700 nm; the second laser light source is a green laser light source with the central wavelength within the range of 491nm-574 nm; the third laser light source is a blue laser light source with the central wavelength within the range of 424nm-490 nm;
the light output intensity of the first laser light source, the light output intensity of the second laser light source and the light output intensity of the third laser light source can be adjusted by the control device.
The output lasers of the first laser light source, the second laser light source and the third laser light source are integrated by the beam splitter prism and then output to the filter wheel (5) through the beam expander (4);
when light is transmitted by the filter wheel, the filter wheel performs color filtering processing on input light according to wave bands through rotation to form light source output light; the control device controls the rotation state of the filter wheel so as to control the color of the light output by the light source.
The light output by the light source is reflected by the imaging surface of the spatial light modulation device to generate imaging light; and the imaging light is imaged on the projection screen after being emitted by the projection shadow head.
An imaging array consisting of a plurality of high-speed digital optical switches is arranged on an imaging surface of the spatial light modulation device; the imaging pixels of the imaging array are formed by digital optical switches; the digital light switch comprises a micro-reflector which can change the open and close state of the light switch by rotating.
Each micro-mirror surface of the imaging surface of the spatial light modulation device corresponds to an imaging pixel; the switching time of the digital optical switch is microsecond magnitude; when the spatial light modulation device operates, if the controller arranged in the spatial light modulation device controls the micro-reflector to be in a light reflection state, the reflected light of the micro-reflector forms bright pixels on corresponding coordinates of a projection screen through the projection shadow head, and if the controller arranged in the spatial light modulation device controls the micro-reflector to be in a non-reflection state, the coordinates of the projection screen corresponding to the micro-reflector are dark to form dark pixels.
The filter wheel is a color wheel which can enable red light, green light and blue light to be sequentially output to the spatial light modulation device when rotating;
when the spatial light modulation device operates, the reflected image of the spatial light modulation device is a color area matched with the light color output by the color wheel, so that the reflected light of the imaging surface of the spatial light modulation device forms a projected image on the projection screen, and the three-color image information of red, green and blue is concentrated by high-speed switching of the projected image by utilizing the phenomenon of human visual system persistence, so that a viewer sees a full-color image on the projection screen.
The light source output light is output to the spatial light modulation device after passing through the aperture diaphragm (6), the reflector (7) and the lens (8);
when the light path structure of the projection device adopts a compact light path, the number of the reflectors is multiple;
the aperture diaphragm is used for filtering the light output by the light source;
the lens is matched with the aperture diaphragm to control the size of a light spot formed by light output by the light source on a modulation window of the spatial light modulator, so that the light spot is internally tangent to the short side of the liquid crystal screen at the modulation window of the spatial light modulator to reduce the interference of redundant reflected light on a projected image.
The high-speed imaging detector is a CCD camera arranged in front of the scattering medium, the projection image on the projection screen is collected through the scattering medium, the imaging resolution is not lower than that of the projection image, and the high-speed imaging frame frequency is not lower than the projection image refreshing frequency;
the projection lens is a long-focus large-aperture lens, the projection mode is a positive projection mode, and the focal length is not less than 140 mm;
the scattering medium is a static scattering medium or a dynamic scattering medium, and when the scattering medium is a dynamic scattering medium, the scattering medium is an optical transmission medium which changes along with time and space, and the method comprises the following steps: smoke, fog or haze;
the projection screen is a diffuse reflection curtain and can perform diffuse reflection at a maximum of 180 degrees;
the projection device except the projection screen is fixed on an optical bread board, and the optical bread board is fixed on the mobile platform; the projection screen is fixed on the movable support.
The projection method adopts an iterative optimization algorithm, so that the projection device can be automatically adjusted according to the change of the projection distance and the scattering medium, when the projection device works, an imaging image is collected from a projection screen by a high-speed imaging detector, the current projection effect is evaluated by a control module according to the imaging image, and the projection light path of the projection device is adjusted by the control module until the high-speed imaging detector captures a picture which tends to be clear, so that the optimal imaging effect is achieved, and the method specifically comprises the following steps:
the method A comprises the steps that on the premise that the absorption conditions of different spectrums of a projection environment and a scattering medium are known, the control module adjusts the light output intensity of the first laser light source, the second laser light source and the third laser light source, so that the light intensity of laser output by the light sources in each wave band is changed, projection light still has enough light intensity after passing through the scattering medium, and the effect of a projection image is optimal;
and B, the control module analyzes the current projected image to obtain the interference condition of the scattering medium to the projected image, and adjusts the light filtering condition of the filter wheel and a digital light switch in the spatial light modulation device to adjust the chromaticity, the contrast and the brightness of the projected image, so that a viewer can still view the high-quality projected image from the projection screen when being interfered by the scattering medium.
The invention has the automatic feedback device and function, can automatically adjust the output power of laser light sources with different wavelengths and the modulation state of the spatial light modulation device according to the projection distance, the characteristics and the dynamic change of a scattering medium in a projection light path, realizes the real-time control of a projection image along with the change of the distance and the scattering medium, and adjusts and optimizes the light intensity and the wave band distribution of a projection light beam in real time, thereby ensuring the high-quality image projection.
The invention relates to a feedback control system based on an iterative optimization algorithm, which comprises the following steps: the iterative optimization algorithm has the advantages of high convergence rate, good robustness and the like, can meet the requirements of the invention on convergence rate and stability, and particularly in the feedback loop of the invention, a laser light source, a spatial light modulation device and a high-speed imaging detector form a feedback system, the adaptation value (namely the definition degree of a picture) is calculated by utilizing the iterative algorithm, the output power of the laser and the on-off state of a micro-mirror unit of the spatial light modulation device are continuously adjusted through a loop mechanism so as to adjust the direction of reflected light, and the repeated loop is carried out continuously until the high-speed imaging detector captures the picture which tends to be clear.
Compared with the prior art, the invention has the following remarkable advantages:
(1) according to the invention, a spatial light modulation device is utilized to modulate an image, firstly, a projected image or a video is loaded on the spatial light modulation device in advance, then, a light beam is reflected by the spatial light modulation device and amplified by a projection lens, on one hand, the modulation speed of the spatial light modulation device is high, so that under the environment with low visibility such as rain, snow, fog and the like, the feedback can be iterated rapidly, and the definition projection penetrating through a scattering medium is realized; on the other hand, the selected projection lens is a standard projection lens with long focal length and large aperture, so that large-field and long-distance projection imaging can be realized simultaneously.
(2) The invention uses the high-power adjustable composite light source composed of three lasers with different wave bands to solve the problem of the absorption peak value of the scattering medium to the light with different wave bands, and can also reduce the influence of the external environment on the projection, so that the projection image definition is optimal after iterative optimization.
(3) The invention realizes the improvement of the projection quality based on the iterative optimization algorithm, can quickly identify and judge the quality of a projected image according to the image detected by the high-speed imaging detector, and correspondingly adjusts the laser light source and the spatial light modulation device to achieve the aim of high-quality projection.
(4) The projection structure is simple, the light path is convenient to build and adjust, all optical devices can be integrally built on the three-dimensional displacement table, and meanwhile, the projection curtain or screen is fixed on the movable frame, so that the projection screen is convenient to carry and is convenient to realize outdoor long-distance projection.
Drawings
The invention is described in further detail below with reference to the following figures and detailed description:
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic projection workflow of the present invention;
FIG. 3 is a schematic diagram of the iterative optimization algorithm of the present invention;
in the figure: 1-a first laser light source; 2-a second laser light source; 3-a third laser light source; 4-a beam expander; 5-a filter wheel; 6-aperture diaphragm; 7-a mirror; 8-a lens; 9-a spatial light modulation device; 10-a projection lens; 11-a scattering medium; 12-projection screen.
Detailed Description
As shown in the figure, the penetrating scattering medium long-distance projection device based on the spatial light modulation device can enable projection light to penetrate through the scattering medium 11 and form an image on a projection screen 12 in high quality, and a light source, the spatial light modulation device 9 and a projection image head 10 are sequentially arranged on a projection light path of the projection device; the projection light path is connected with the control device; the control device is connected with a high-speed imaging detector 13 which can collect imaging images from a projection screen, the current projection effect is evaluated by the imaging images collected by the high-speed imaging detector, and a projection light path is adjusted to optimize the imaging effect.
The control device is connected with the light source; the light source comprises a first laser light source 1, a second laser light source 2 and a third laser light source 3;
the first laser light source is a red laser light source with the central wavelength within the range of 615nm-700 nm; the second laser light source is a green laser light source with the central wavelength within the range of 491nm-574 nm; the third laser light source is a blue laser light source with the central wavelength within the range of 424nm-490 nm;
the light output intensity of the first laser light source, the light output intensity of the second laser light source and the light output intensity of the third laser light source can be adjusted by the control device.
The output lasers of the first laser light source, the second laser light source and the third laser light source are integrated by the beam splitter prism and then output to the filter wheel 5 through the beam expander 4;
when light is transmitted by the filter wheel, the filter wheel performs color filtering processing on input light according to wave bands through rotation to form light source output light; the control device controls the rotation state of the filter wheel so as to control the color of the light output by the light source.
The light output by the light source is reflected by the imaging surface of the spatial light modulation device to generate imaging light; and the imaging light is imaged on the projection screen after being emitted by the projection shadow head.
An imaging array consisting of a plurality of high-speed digital optical switches is arranged on an imaging surface of the spatial light modulation device; the imaging pixels of the imaging array are formed by digital optical switches; the digital light switch comprises a micro-reflector which can change the open and close state of the light switch by rotating.
Each micro-mirror surface of the imaging surface of the spatial light modulation device corresponds to an imaging pixel; the switching time of the digital optical switch is microsecond magnitude; when the spatial light modulation device operates, if the controller arranged in the spatial light modulation device controls the micro-reflector to be in a light reflection state, the reflected light of the micro-reflector forms bright pixels on corresponding coordinates of a projection screen through the projection shadow head, and if the controller arranged in the spatial light modulation device controls the micro-reflector to be in a non-reflection state, the coordinates of the projection screen corresponding to the micro-reflector are dark to form dark pixels.
The filter wheel is a color wheel which can enable red light, green light and blue light to be sequentially output to the spatial light modulation device when rotating;
when the spatial light modulation device operates, the reflected image of the spatial light modulation device is a color area matched with the light color output by the color wheel, so that the reflected light of the imaging surface of the spatial light modulation device forms a projected image on the projection screen, and the three-color image information of red, green and blue is concentrated by high-speed switching of the projected image by utilizing the phenomenon of human visual system persistence, so that a viewer sees a full-color image on the projection screen.
The light source output light is output to the spatial light modulation device after passing through the aperture diaphragm 6, the reflector 7 and the lens 8;
when the light path structure of the projection device adopts a compact light path, the number of the reflectors is multiple;
the aperture diaphragm is used for filtering the light output by the light source;
the lens is matched with the aperture diaphragm to control the size of a light spot formed by light output by the light source on a modulation window of the spatial light modulator, so that the light spot is internally tangent to the short side of the liquid crystal screen at the modulation window of the spatial light modulator to reduce the interference of redundant reflected light on a projected image.
The high-speed imaging detector is a CCD camera arranged in front of the scattering medium, the projection image on the projection screen is collected through the scattering medium, the imaging resolution is not lower than that of the projection image, and the high-speed imaging frame frequency is not lower than the projection image refreshing frequency;
the projection lens is a long-focus large-aperture lens, the projection mode is a positive projection mode, and the focal length is not less than 140 mm;
the scattering medium is a static scattering medium or a dynamic scattering medium, and when the scattering medium is a dynamic scattering medium, the scattering medium is an optical transmission medium which changes along with time and space, and the method comprises the following steps: smoke, fog or haze;
the projection screen is a diffuse reflection curtain and can perform diffuse reflection at a maximum of 180 degrees;
the projection device except the projection screen is fixed on an optical bread board, and the optical bread board is fixed on the mobile platform; the projection screen is fixed on the movable support.
The projection method adopts an iterative optimization algorithm, so that the projection device can be automatically adjusted according to the change of the projection distance and the scattering medium, when the projection device works, an imaging image is collected from a projection screen by a high-speed imaging detector, the current projection effect is evaluated by a control module according to the imaging image, and the projection light path of the projection device is adjusted by the control module until the high-speed imaging detector captures a picture which tends to be clear, so that the optimal imaging effect is achieved, and the method specifically comprises the following steps:
the method A comprises the steps that on the premise that the absorption conditions of different spectrums of a projection environment and a scattering medium are known, the control module adjusts the light output intensity of the first laser light source, the second laser light source and the third laser light source, so that the light intensity of laser output by the light sources in each wave band is changed, projection light still has enough light intensity after passing through the scattering medium, and the effect of a projection image is optimal;
and B, the control module analyzes the current projected image to obtain the interference condition of the scattering medium to the projected image, and adjusts the light filtering condition of the filter wheel and a digital light switch in the spatial light modulation device to adjust the chromaticity, the contrast and the brightness of the projected image, so that a viewer can still view the high-quality projected image from the projection screen when being interfered by the scattering medium.
In this example, the light outputs of the first laser light source, the second laser light source, and the third laser light source are 635nm red laser light, 532nm green laser light, and 473nm blue laser light, respectively.
In this example, the spatial light modulation device is a kind of optical switch, and its modulation window is composed of 2560 × 1600 micro mirrors, each micro mirror unit is a separate individual and can be flipped by different angles, each micro mirror unit has three stable states: +12 degrees or +10 degrees (on), 0 degrees (no signal), -12 degrees or-10 degrees (off). When a signal "1" is given to the micromirror, which is deflected by +12 degrees or +10 degrees, the reflected light is imaged on the screen through the projection objective lens exactly in the direction of the optical axis, forming a bright pixel. When the mirror is displaced from the equilibrium position by-12 degrees or-10 degrees (signal "0"), the reflected beam will not pass through the projection lens and thus appear as a dark pixel. The binary states of '1' and '0' of the control signal respectively correspond to the two states of 'on' and 'off' of the micro-mirror.
The present example is used for long-distance projection, and the long-focus lens is selected according to requirements, which is favorable for long-distance imaging, and the standard lens with larger aperture is selected for improving the image definition of the scattering medium, which is favorable for fully utilizing energy. When an image is projected, the distance between the projection lens and the spatial light modulation device is generally between 5 and 10 cm.
In this embodiment, the spatial light modulator adopts a DMD, the control module adopts a computer, and the deployment and working steps are as follows;
(1) the laser devices 1, 2 and 3 are placed on a prepared optical bread board in advance, an aperture diaphragm or a power meter is used for calibrating and collimating each laser beam, two beam splitting prisms are used for integrating three laser beams into one laser beam, in order to ensure that the superposition degree of a composite laser beam is higher, the three laser beams are strictly consistent in height, the three laser beams of red, green and blue need to be accurately calibrated and collimated, so that the laser beams are completely superposed, the horizontality of the beam splitting prisms is ensured to be better, and in addition, the laser devices are prevented from being overlarge in the laser calibration and collimation process, so that the eyes are prevented from being damaged in the calibration process;
(2) the beam expander 4 is used for expanding the composite laser, the size and the brightness of a light spot after expanding the beam are generally uniform as the best, because the light beam on the outer ring of the expanded light spot is not uniform, the aperture diaphragm 6 can be used for filtering, and the part with the uniform inner ring of the light spot is selected as a used light source;
(3) the reflector 7 reflects the expanded light beam to a modulation window of the spatial light modulation device through a lens 8 (focal length f =50 mm) at an included angle of 45 degrees, loads the light beam to an output image of the spatial light modulation device, then reaches the projection lens 10 after reflection, and then penetrates through a scattering medium 11 to project to a diffuse emission curtain 12 at a far distance; the size of the light spot irradiated on the modulation window of the spatial light modulator 9 is optimal by taking the minor axis length of which the diameter is slightly larger than the modulation window of the spatial light modulator as the length, so that the phenomenon that the redundant stray light spots are reflected into a projection lens to influence the projection effect can be reduced, and the size of the light spot irradiated on the modulation window of the DMD can be controlled by controlling the distance of the lens 8;
(4) the high-speed imaging detector captures a projected image of 50 meters away and transmits the projected image to a computer used as a control module, the computer calculates a fitness value (namely the definition degree of a picture) by using an iterative optimization algorithm, and the output power of the laser and the on-off state of a micro mirror of the spatial light modulation device are continuously adjusted by a circulation mechanism so as to adjust the definition degree of the image until the picture detected by the high-speed imaging detector reaches an expected value.
Furthermore, the included angle between the spatial light modulator and the incident light beam is about 12 ℃, and the included angle between the spatial light modulator and the incident light beam and the distance between the spatial light modulator and the projection lens are continuously and finely adjusted in the system construction process, so that an image projected on the curtain has no ghost or stray light spots until the image obtained by the high-speed imaging detector is clear and visible.
Furthermore, above-mentioned projection lens can be supported control by two independent elevating platforms, and projection lens requires the level to be placed to guarantee that the projection figure can parallel outgoing, if projection lens and projection curtain contained angle produce the deviation, will lead to the image slope, can't project on the curtain completely, influence high-speed imaging detector's image acquisition and feedback.
Further, the high-speed imaging detector is used for capturing images on a projection curtain or a screen and feeding the images back to the computer. The exposure time and the frame rate of the high-speed imaging detector are required to be set according to the influence of actual projection on the refresh frequency.
Furthermore, except the projection curtain or screen, the other components of the long-distance projection system are fixed on an optical bread board with the size of about 600 x 600mm, and the optical bread board is fixedly supported by a movable platform; the projection curtain or the screen is fixed on the movable frame, the projection direction of the whole system can be freely adjusted, and the portability is greatly improved, so that the system is suitable for outdoor long-distance projection.
Claims (10)
1. A transmissive scattering medium teleprojection apparatus based on spatial light modulation devices, which allows projection light to penetrate a scattering medium (11) and to be imaged on a projection screen (12) with high quality, characterized in that: a light source, a spatial light modulation device (9) and a projection image head (10) are sequentially arranged on a projection light path of the projection device; the projection light path is connected with the control device; the control device is connected with a high-speed imaging detector (13) capable of collecting imaging images from the projection screen, the current projection effect is evaluated through the imaging images collected by the high-speed imaging detector, and the projection light path is adjusted to optimize the imaging effect.
2. A transmissive scattering medium teleprojection apparatus based on spatial light modulation device as claimed in claim 1 wherein: the control device is connected with the light source; the light source comprises a first laser light source (1), a second laser light source (2) and a third laser light source (3);
the first laser light source is a red laser light source with the central wavelength within the range of 615nm-700 nm; the second laser light source is a green laser light source with the central wavelength within the range of 491nm-574 nm; the third laser light source is a blue laser light source with the central wavelength within the range of 424nm-490 nm;
the light output intensity of the first laser light source, the light output intensity of the second laser light source and the light output intensity of the third laser light source can be adjusted by the control device.
3. A transmissive scattering medium teleprojection apparatus based on spatial light modulation device as claimed in claim 2 wherein: the output lasers of the first laser light source, the second laser light source and the third laser light source are integrated by the beam splitter prism and then output to the filter wheel (5) through the beam expander;
when light is transmitted by the filter wheel, the filter wheel performs color filtering processing on input light according to wave bands through rotation to form light source output light; the control device controls the rotation state of the filter wheel so as to control the color of the light output by the light source.
4. A transmissive scattering medium teleprojection apparatus based on spatial light modulation device as claimed in claim 3 wherein: the light output by the light source is reflected by the imaging surface of the spatial light modulation device to generate imaging light; and the imaging light is imaged on the projection screen after being emitted by the projection shadow head.
5. A transmissive scattering medium teleprojection apparatus based on spatial light modulation device as claimed in claim 4 wherein: an imaging array consisting of a plurality of high-speed digital optical switches is arranged on an imaging surface of the spatial light modulation device; the imaging pixels of the imaging array are formed by digital optical switches; the digital light switch comprises a micro-reflector which can change the open and close state of the light switch by rotating.
6. A transmissive scattering medium teleprojection apparatus based on spatial light modulation devices as claimed in claim 5, wherein: each micro-mirror surface of the imaging surface of the spatial light modulation device corresponds to an imaging pixel; the switching time of the digital optical switch is microsecond magnitude; when the spatial light modulation device operates, if the controller arranged in the spatial light modulation device controls the micro-reflector to be in a light reflection state, the reflected light of the micro-reflector forms bright pixels on corresponding coordinates of a projection screen through the projection shadow head, and if the controller arranged in the spatial light modulation device controls the micro-reflector to be in a non-reflection state, the coordinates of the projection screen corresponding to the micro-reflector are dark to form dark pixels.
7. A transmissive scattering medium teleprojection apparatus based on spatial light modulation devices as claimed in claim 5, wherein: the filter wheel is a color wheel which can enable red light, green light and blue light to be sequentially output to the spatial light modulation device when rotating;
when the spatial light modulation device operates, the reflected image of the spatial light modulation device is a color area matched with the light color output by the color wheel, so that the reflected light of the imaging surface of the spatial light modulation device forms a projected image on the projection screen, and the three-color image information of red, green and blue is concentrated by high-speed switching of the projected image by utilizing the phenomenon of human visual system persistence, so that a viewer sees a full-color image on the projection screen.
8. A transmissive scattering medium teleprojection apparatus based on spatial light modulation device as claimed in claim 3 wherein: the light source output light is output to the spatial light modulation device after passing through the aperture diaphragm (6), the reflector (7) and the lens (8);
when the light path structure of the projection device adopts a compact light path, the number of the reflectors is multiple;
the aperture diaphragm is used for filtering the light output by the light source;
the lens is matched with the aperture diaphragm to control the size of a light spot formed by light output by the light source on a modulation window of the spatial light modulator, so that the light spot is internally tangent to the short side of the liquid crystal screen at the modulation window of the spatial light modulator to reduce the interference of redundant reflected light on a projected image.
9. A transmissive scattering medium teleprojection apparatus based on spatial light modulation device as claimed in claim 3 wherein: the high-speed imaging detector is a CCD camera arranged in front of the scattering medium, the projection image on the projection screen is collected through the scattering medium, the imaging resolution is not lower than that of the projection image, and the high-speed imaging frame frequency is not lower than the projection image refreshing frequency;
the projection lens is a long-focus large-aperture lens, the projection mode is a positive projection mode, and the focal length is not less than 140 mm;
the scattering medium is a static scattering medium or a dynamic scattering medium, and when the scattering medium is a dynamic scattering medium, the scattering medium is an optical transmission medium which changes along with time and space, and the method comprises the following steps: smoke, fog or haze;
the projection screen is a diffuse reflection curtain and can perform diffuse reflection at a maximum of 180 degrees;
the projection device except the projection screen is fixed on an optical bread board, and the optical bread board is fixed on the mobile platform; the projection screen is fixed on the movable support.
10. A remote projection method of a penetrating scattering medium based on a spatial light modulation device, using the remote projection apparatus of claim 7, characterized in that: the projection method adopts an iterative optimization algorithm, so that the projection device can be automatically adjusted according to the change of the projection distance and the scattering medium, when the projection device works, an imaging image is collected from a projection screen by a high-speed imaging detector, the current projection effect is evaluated by a control module according to the imaging image, and the projection light path of the projection device is adjusted by the control module until the high-speed imaging detector captures a picture which tends to be clear, so that the optimal imaging effect is achieved, and the method specifically comprises the following steps:
the method A comprises the steps that on the premise that the absorption conditions of different spectrums of a projection environment and a scattering medium are known, the control module adjusts the light output intensity of the first laser light source, the second laser light source and the third laser light source, so that the light intensity of laser output by the light sources in each wave band is changed, projection light still has enough light intensity after passing through the scattering medium, and the effect of a projection image is optimal;
and B, the control module analyzes the current projected image to obtain the interference condition of the scattering medium to the projected image, and adjusts the light filtering condition of the filter wheel and a digital light switch in the spatial light modulation device to adjust the chromaticity, the contrast and the brightness of the projected image, so that a viewer can still view the high-quality projected image from the projection screen when being interfered by the scattering medium.
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Application publication date: 20220107 |