CN115793239A - Holographic near-to-eye display system and method based on multiple spatial light modulators - Google Patents

Abstract

The embodiment of the invention discloses a holographic near-eye display system and method based on a multi-spatial light modulator. The holographic near-eye display system includes a control module, a plurality of spatial light modulation subsystems, a second beam splitter, a second lens group, and a third beam splitter, and each spatial light modulation subsystem includes a light source, a polarizer, a first beam splitter, The spatial light modulator, the first lens group and the aperture; the divergent light emitted by the light source is collimated by the first lens group to be parallel light incident on the spatial light modulator, and is reflected and diffracted by the spatial light modulator to form a three-dimensional imaging beam; the three-dimensional imaging beam It enters the human eye through the second beam splitter, the second lens group and the third beam splitter. The embodiment of the present invention can project a three-dimensional image with real depth of field information, eliminating visual fatigue of the human eye; and, through the joint action of multiple spatial light modulators' field of view seamless splicing and field of view magnification system, the hologram can be enlarged. The field of view of the near-eye display system can obtain a three-dimensional display effect with a large field of view.

Description

A holographic near-eye display system and method based on multiple spatial light modulators

technical field

Embodiments of the present invention relate to the field of virtual display technology, and in particular to a holographic near-eye display system and method based on a multi-spatial light modulator.

Background technique

At present, near-eye augmented reality (Augmented Reality, AR) display technology mainly uses organic electroluminescence display (OLED) and liquid crystal on silicon (LCos) screens, and the image source provided is a two-dimensional image. The 3D image display effect needs to be realized through binocular parallax technology, which inevitably causes a mismatch between binocular convergence adjustment and visual refraction adjustment, resulting in visual fatigue.

As a true three-dimensional display technology, holographic three-dimensional display technology can completely record and reconstruct the light field of three-dimensional objects, and provide all the information required by the human visual system. Due to the limitations of semiconductor technology, the pixel size of the current commercial pixelated spatial light modulator (Spatial Light Modulator, SLM) is difficult to reach the wavelength level of visible light, and the spatial bandwidth product is seriously insufficient, resulting in the holographic 3D based on a single spatial light modulator. The field of view angle of the reproduced image is small, and the ideal three-dimensional display effect cannot be achieved.

Contents of the invention

The invention provides a holographic near-eye display system and method based on a multi-spatial light modulator to realize a holographic three-dimensional display with a large viewing angle.

In the first aspect, an embodiment of the present invention provides a holographic near-eye display system based on a multi-spatial light modulator, including a control module, multiple spatial light modulation subsystems, a second beam splitter, a second lens group, and a third beam splitter , each spatial light modulation subsystem includes a light source, a polarizer, a first beam splitter, a spatial light modulator, a first lens group and an aperture;

The control module calculates the three-dimensional image information to be displayed into a two-dimensional hologram, and loads the synchronous output onto the spatial light modulators in the multiple spatial light modulation subsystems for display, and synchronously controls the multiple spatial light modulation subsystems The light source in the light modulation subsystem emits light;

In the same spatial light modulation subsystem, the divergent light emitted by the light source passes through the polarizer, is reflected by the first beam splitter, and is collimated by the first lens group as parallel light incident on the On the spatial light modulator, the three-dimensional imaging beam is formed by reflection and diffraction of the spatial light modulator;

The three-dimensional imaging light beams formed in different spatial light modulation subsystems respectively pass through the first lens group, the aperture, the second beam splitter and the second lens group to form a multi-spatial light modulator After the field of view splicing system and the field of view magnification system, it is reflected by the third beam splitter and enters the human eye.

Optionally, the control module includes: a main control unit, a control program interface unit, an external communication interface, a hologram calculation unit, a storage unit, an SLM drive unit, and a light source drive unit;

The main control unit is electrically connected to the storage unit, the control program interface unit, the hologram calculation unit, the external communication interface, and the SLM drive unit.

Optionally, in any one of the spatial light modulation subsystems, the focal length f1 of the first lens group is greater than the focal length f2 of the second lens group, and the first lens group and the second lens group The optical distance between the groups is f1+f2, and the magnification of the field angle of the first lens group and the second lens group is f1/f2.

Optionally, taking the imaging optical axis of the holographic near-eye display system as a reference, the inclination angles of the spatial light modulators in the plurality of spatial light modulation subsystems are sequentially increased, and the two spatial light modulators with adjacent inclination angles The included angle of the zero-order beam reflected by the light modulator is α, and the viewing angle of any one of the spatial light modulators is θ, where α≤θ.

Optionally, the number of the spatial light modulators is N, and N is an integer greater than or equal to 2, and the viewing angle θ _t of the holographic near-eye display system satisfies: θ _t =f ₁ /f ₂ ·[θ+ (N-1)α].

Optionally, in any one of the spatial light modulation subsystems, the distance S1 between the spatial light modulator and the first lens group is smaller than the focal length f1 of the first lens group.

Optionally, in any one of the spatial light modulation subsystems, the diaphragm is located on a Fourier transform plane of the first lens group.

Optionally, the light source is a coherent monochromatic laser light source or a colored laser light source, or the light source is a monochromatic LED light source or a color LED light source with a set coherence.

Optionally, the spatial light modulator is a reflective or transmissive spatial light modulator, and the modulation mode is phase modulation or amplitude modulation.

In the second aspect, the embodiment of the present invention also provides a holographic near-eye display method based on a multi-spatial light modulator. The holographic near-eye display system based on a multi-spatial light modulator described in any one of the first aspects is used to perform multi-spatial light modulator-based holographic near-eye display system. Holographic near-eye displays with spatial light modulators.

In the large-field-of-view holographic near-eye display system based on multiple spatial light modulators provided by the embodiment of the present invention, by setting up multiple spatial light modulation subsystems and forming a field-of-view splicing system and a field-of-view amplification system, the holographic algorithm is used to The intensity information and depth information of the three-dimensional image are calculated into the ordinary two-dimensional hologram and loaded on the liquid crystal spatial light modulator. Using the phase modulation capability of the spatial light modulator, a three-dimensional image with real depth information can be projected, thereby Eliminate the visual fatigue of the human eye; and, through the joint action of the seamless splicing of the field of view of multiple spatial light modulators and the field of view amplification system, the field of view of the entire holographic near-eye display system can be expanded to obtain a large field of view 3D display effect.

Description of drawings

Fig. 1 is a schematic structural diagram of a holographic near-eye display system based on a multi-spatial light modulator provided by an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a control module provided by an embodiment of the present invention;

Fig. 3 is a splicing equivalent schematic diagram of the holographic near-eye display system shown in Fig. 1;

Fig. 4 is an equivalent schematic diagram of the arrangement of a multi-spatial light modulator provided by an embodiment of the present invention;

FIG. 5 is an enlarged schematic diagram of the holographic near-eye display system shown in FIG. 1 .

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, only some structures related to the present invention are shown in the drawings but not all structures.

Fig. 1 is a schematic structural diagram of a holographic near-eye display system based on multiple spatial light modulators provided by an embodiment of the present invention. Referring to Fig. 1, the holographic near-eye display system includes a control module 101, a plurality of spatial light modulation subsystems, a second The beam splitter 114, the second lens group 115 and the third beam splitter 116, each spatial light modulation subsystem includes a light source, a polarizer, a first beam splitter, a spatial light modulator, a first lens group and an aperture. In the figure, two spatial light modulation subsystems are taken as examples to illustrate, including a first spatial light modulation subsystem and a second spatial light modulation subsystem. The first spatial light modulation subsystem includes a first light source 102, a first polarizer 103 , the first sub-beam splitter 104 , the first spatial light modulator 105 , the first sub-lens group 106 and the first aperture 107 . The second spatial light modulation subsystem includes a second light source 108 , a second polarizer 109 , a second sub-beam splitter 110 , a second spatial light modulator 111 , a second sub-lens group 112 and a second diaphragm 113 .

In the first spatial light modulation subsystem, the first beam splitter is the first sub-beam splitter 104 , and the first lens group is the first sub-lens group 106 . In the second spatial light modulation subsystem, the first beam splitter is the second sub-beam splitter 110 , and the first lens group is the second sub-lens group 112 .

The control module 101 calculates the three-dimensional image information to be displayed into a two-dimensional hologram, and loads the synchronous output onto the spatial light modulators in the multiple spatial light modulation subsystems for display, and synchronously controls the holograms in the multiple spatial light modulation subsystems. The light source emits light; in the same spatial light modulation subsystem, the divergent light emitted by the light source passes through the polarizer, is reflected by the first beam splitter, and is collimated by the first lens group to be parallel light and is incident on the spatial light modulator. The three-dimensional imaging beams are formed by reflection and diffraction of the spatial light modulator; the three-dimensional imaging beams formed in different spatial light modulation subsystems are respectively viewed by the multi-spatial light modulator composed of the first lens group, diaphragm, second beam splitter and second lens group. After the field angle splicing system and field angle magnification system, it is reflected by the third beam splitter and enters the human eye.

Wherein, for the first spatial light modulation subsystem, the control module 101 calculates the three-dimensional image information to be displayed into a two-dimensional hologram, and the synchronous output is loaded to the first spatial light modulator 105 for display, and the first light source 102 is synchronously controlled Light emission; in the spatial light modulation subsystem, the divergent light emitted by the first light source 102 passes through the first polarizer 103, is reflected by the first sub-beam splitter 104, and is collimated into parallel light by the first sub-lens group 106 It is incident on the first spatial light modulator 105, and is reflected and diffracted by the first spatial light modulator 105 to form a three-dimensional imaging beam. For the second spatial light modulation subsystem, the control module 101 calculates the three-dimensional image information to be displayed into a two-dimensional hologram, and synchronously outputs it to the second spatial light modulator 111 for display, and synchronously controls the second light source 108 to emit light; In this spatial light modulation subsystem, the divergent light emitted by the second light source 108 passes through the second polarizer 109, is reflected by the second sub-beam splitter 110, and is collimated by the second sub-lens group 112 to become parallel light incident on the On the second spatial light modulator 111 , the three-dimensional imaging beam is formed by reflection and diffraction by the second spatial light modulator 111 .

In the large-field-of-view holographic near-eye display system based on multiple spatial light modulators provided by the embodiment of the present invention, by setting up multiple spatial light modulation subsystems and forming a field-of-view splicing system and a field-of-view amplification system, the holographic algorithm is used to The intensity information and depth information of the three-dimensional image are calculated into the ordinary two-dimensional hologram and loaded on the liquid crystal spatial light modulator. Using the phase modulation capability of the spatial light modulator, a three-dimensional image with real depth information can be projected, thereby Eliminate the visual fatigue of the human eye; and, through the joint action of the seamless splicing of the field of view of multiple spatial light modulators and the field of view amplification system, the field of view of the entire holographic near-eye display system can be expanded to obtain a large field of view 3D display effect.

The control module 101 mainly completes the hologram calculation and loading of image information, as well as the synchronous control of spatial light modulation and light source. Fig. 2 is a schematic structural diagram of a control module provided by an embodiment of the present invention. Referring to Fig. 2, specifically, the control module 101 in this embodiment may include: a main control unit 201, a control program interface unit 202, an external communication interface 203, a holographic Figure calculation unit 204, storage unit 205, SLM drive unit 206 and light source drive unit 207; main control unit 201 and control program interface unit 202, external communication interface 203, hologram calculation unit 204, storage unit 205, SLM drive unit 206 respectively electrical connection.

The main control unit 201 completes the control work of the entire system; the control program interface unit 202 mainly provides the man-machine interface interface; the external communication interface 203 mainly includes wired interfaces such as video and data, or wireless interfaces such as wireless, Bluetooth, and infrared to receive external data; The image calculation unit 204 generates a hologram through the corresponding three-dimensional image information or data through a hologram algorithm, and outputs it to the spatial light modulator driving unit through the main control unit, so as to drive the spatial light modulation to modulate the light beam incident on it. Output the corresponding three-dimensional image information; the main control unit 201 can also output and display the hologram stored in advance by the internal or external storage unit 205 on the spatial light modulator; the main control unit 201 can realize multiple spatial light modulators and light sources synchronous drive.

In the embodiment of the present invention, the light source can be a monochromatic laser light source or a color laser light source with coherence, or a monochromatic LED light source or a color LED light source with predetermined coherence. In addition, the spatial light modulator adopts a reflective spatial light modulator.

Fig. 3 is a mosaic equivalent schematic diagram of the holographic near-eye display system shown in Fig. 1. Referring to Fig. 1 and Fig. 3, the first sub-lens group 106 and the first aperture 107 in the first spatial light modulation subsystem The second sub-lens group 112 and the second diaphragm 113 as well as the second beam splitter 114 and the second lens group 115 in the light modulation subsystem can constitute a multi-spatial light modulator field of view splicing system. The mirror image of the second spatial light modulator 111 with respect to the second beam splitter 114 is a second virtual spatial light modulator 111 ′, and the display field of view of the second virtual spatial light modulator 111 ′ and the first spatial light modulator 105 is the same. seam together.

In addition, the first sub-lens group 106, the first diaphragm 107 and the second lens group 115 in the first spatial light modulation subsystem can form a viewing angle magnification system, and the second sub-lens in the second spatial light modulation subsystem The group 112, the second diaphragm 113 and the second lens group 115 can also form a field angle magnification system. The three-dimensional imaging light beams respectively formed by the first spatial light modulator 105 and the second spatial light modulator 111 enter the human eye through the third beam splitter 116 through the above-mentioned multi-spatial light modulator field of view splicing system and field of view amplification system , a three-dimensional stereoscopic image with an enlarged viewing angle can be formed. At the same time, the light beam of the external environment can also enter the human eye through the third beam splitter 116, and an AR image can be presented at the human eye end.

It should be noted that in the holographic near-eye display system provided by the embodiment of the present invention, the first lens group in any one of the spatial light modulation subsystems, that is, the first sub-lens group 106 and the second sub-lens group 112, should not only The front lens group of the magnification system also has the function of collimating the incident divergent light into parallel light. In addition, the light sources, polarizers, first beam splitters, spatial light modulators and first lens groups in any two spatial light modulation subsystems correspondingly have the same optical parameters. For example, the first spatial light modulator 105 and the second spatial light modulator 111 are placed in a mirror-image symmetrical relationship, and have the same viewing angle; the first sub-lens group 106 and the second sub-lens group 112 are placed in a mirror-symmetrical relationship, with same focal length. In addition, for the two subsystems, although the first aperture 107 and the second aperture 113 are placed in a mirror-symmetrical relationship with respect to the second beam splitter 114, they have different passing aperture positions, and respectively pass through the first spatial light modulator 105 An imaging area different from that of the second spatial light modulator 111.

In the holographic near-eye display system provided by the present invention, with the imaging optical axis of the holographic near-eye display system as the reference, the inclination angles of the spatial light modulators in the multiple spatial light modulation subsystems are successively increased, and the two adjacent inclination angles The included angle of the zero-order light beam reflected by the spatial light modulator is α, and the viewing angle of any spatial light modulator is θ, where α≤θ.

Continuing to take the holographic near-eye display system shown in FIG. 1 as an example, the angle between the second beam splitter 114 and the horizontal direction is 45°, on this basis, the angle between the first spatial light modulator 105 and the horizontal direction is α/4, The included angle between the second spatial light modulator 111 and the vertical direction is also α/4. At this time, therefore, the angle between the first spatial light modulator 105 and the second virtual spatial light modulator 111' is α/2, and the angle between the zero-order light beams reflected by the two spatial light modulators is α, as shown in Fig. 3. Define the angle α between the first spatial light modulator 105 and the second virtual spatial light modulator 111 ′ as the splicing angle. In order to ensure that there is no image crosstalk when observed by human eyes, the splicing angle must satisfy α≤θ. It can be understood that when the angle α between the zero-order beams reflected by two spatial light modulators is greater than the field of view angle of a single spatial light modulator, It means that the fields of view of the two spatial light modulators do not overlap each other, that is, seamless splicing cannot be realized.

For the holographic near-eye display shown in Figure 1, the angle between the zero-order light beams reflected by the first spatial light modulator 105 and the second spatial light modulator 111 is α, and the field of view obtained after splicing is θ+α . Fig. 4 is an equivalent schematic diagram of the arrangement of multiple spatial light modulators provided by the embodiment of the present invention. Referring to Fig. 4, when multiple spatial light modulators are set in the holographic near-eye display system, multiple spatial light The imaging optical axis of the display system is tilted sequentially based on the reference, and the tilt angle increases. At this time, the zero-order light beams reflected by multiple spatial light modulators are respectively incident on different positions of the field of view, which effectively expands the field of view. It can be understood that when the angle between the zero-order beams reflected by two adjacent spatial light modulators with an inclination angle is α, the angle between the zero-order beams reflected by the two outermost spatial light modulators should be ( N-1) α, N is the number of spatial light modulators, and N is a natural number greater than or equal to 2. Based on the field angle of each spatial light modulator being θ, it can be known that the stitching angle of field of view formed by all spatial light modulators is θ+(N-1)α.

In addition, in the embodiment of the present invention, in any spatial light modulation subsystem, the focal length f1 of the first lens group is greater than the focal length f2 of the second lens group, and the optical distance between the first lens group and the second lens group is f1+f2, and the magnification of the field angle of the first lens group and the second lens group is f1/f2. Further, the number of spatial light modulators is N, and N is an integer greater than or equal to 2, and the viewing angle θ _t of the holographic near-eye display system satisfies: θ _t =f ₁ /f ₂ ·[θ+(N-1) α]. Further optionally, in any one of the spatial light modulation subsystems, the distance S1 between the spatial light modulator and the first lens group is smaller than the focal length f1 of the first lens group.

Fig. 5 is an enlarged schematic diagram of the holographic near-eye display system shown in Fig. 1. Referring to Fig. 1 and Fig. 5, the magnification system of the holographic near-eye display is mainly used to enlarge the imaging field of view. As mentioned above, the first spatial light modulation The first sub-lens group 106, the first diaphragm 107 and the second lens group 115 in the subsystem can form a viewing angle magnification system, and the second sub-lens group 112 and the second diaphragm in the second spatial light modulation subsystem 113 and the second lens group 115 can also form a viewing angle magnification system.

The focal lengths of the first sub-lens group 106 and the second sub-lens group 112 are both f ₁ , the focal length of the second lens group 115 is f ₂ , and f ₁ > f ₂ , the first sub-lens group 106 and the second lens group 115 The distance between them is f ₁ +f ₂ , the magnification of the viewing angle is f ₁ /f ₂ , and the viewing angle of the whole system is θ _t = f ₁ /f ₂ ·[θ+(N-1)α] .

In the viewing angle magnification system, in order to expand the exit pupil distance S ₂ of the display system, the distance between the first spatial light modulator 105 and the first sub-lens group 106 and the distance between the second spatial light modulator 111 and the second sub-lens group The distance between 112 is S ₁ , if S ₁ < f ₁ , the exit pupil distance S ₂ can be expressed as S ₂ = f ₂ + f ₂ ·(f ₂ /f ₁ )-(f ₂ /f ₁ ) ² · S ₁ .

In addition, in any spatial light modulation subsystem, the diaphragm should be located on the Fourier transform plane of the first lens group. As shown in FIG. 1 , the first diaphragm 107 is located on the Fourier transform plane of the first sub-lens group 106 , and the second diaphragm 113 is located on the Fourier transform plane of the second sub-lens group 112 . By designing the corresponding aperture stop, the interference of multi-order diffraction image and zero-order image pair imaging can be filtered out.

Based on the same inventive concept, an embodiment of the present invention also provides a holographic near-eye display method based on a multi-spatial light modulator. Holographic near-eye display with multiple spatial light modulators. It can be understood that since the holographic near-eye display method is implemented by the holographic near-eye display system provided in the above embodiment, the same or similar beneficial effects of the above-mentioned holographic near-eye display system will not be repeated here.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described here, and various obvious changes, readjustments, mutual combinations and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention, and the present invention The scope is determined by the scope of the appended claims.

Claims (10)

1. A holographic near-to-eye display system based on multiple spatial light modulators is characterized by comprising a control module, multiple spatial light modulation subsystems, a second beam splitter, a second lens group and a third beam splitter, wherein each spatial light modulation subsystem comprises a light source, a polaroid, a first beam splitter, a spatial light modulator, a first lens group and a diaphragm;

the control module calculates three-dimensional image information to be displayed into a two-dimensional hologram, synchronously outputs and loads the two-dimensional hologram to the spatial light modulators in the spatial light modulation subsystems for display, and synchronously controls the light sources in the spatial light modulation subsystems to emit light;

in the same spatial light modulation subsystem, divergent light emitted by the light source penetrates through the polaroid, is reflected by the first beam splitter, is collimated into parallel light by the first lens group, is incident on the spatial light modulator, and is reflected and diffracted by the spatial light modulator to form a three-dimensional imaging light beam;

and the three-dimensional imaging light beams formed in different spatial light modulation subsystems respectively pass through a multi-spatial light modulator visual angle splicing system and a visual angle amplifying system which are formed by the first lens group, the diaphragm, the second beam splitter and the second lens group, and then are reflected by the third beam splitter to enter human eyes.

2. The holographic near-eye display system of claim 1, wherein the control module comprises: the device comprises a main control unit, a control program interface unit, an external communication interface, a hologram calculation unit, a storage unit, an SLM driving unit and a light source driving unit;

the main control unit is electrically connected with the storage unit, the control program interface unit, the hologram calculation unit, the external communication interface and the SLM driving unit respectively.

3. The holographic near-eye display system of claim 1,

in any one of the spatial light modulation subsystems, a focal length f1 of the first lens group is greater than a focal length f2 of the second lens group, an optical path between the first lens group and the second lens group is f1+ f2, and a magnification of a field angle of the first lens group and the second lens group is f1/f2.

4. The holographic near-eye display system of claim 3, wherein the tilt angles of the spatial light modulators in the plurality of spatial light modulation subsystems are sequentially increased based on an imaging optical axis of the holographic near-eye display system, an included angle between zero-order light beams reflected by two spatial light modulators adjacent to the tilt angles is α, and an angle of view of any one of the spatial light modulators is θ, where α ≦ θ.

5. The holographic near-eye display system of claim 4, wherein the number of spatial light modulators is N, N being an integer greater than or equal to 2, the holographic near-eye display system having an angle of view θ _t Satisfies the following conditions: theta.theta. _t ＝f ₁ /f ₂ ·[θ+(N-1)α]。

6. The holographic near-to-eye display system of claim 1, in any of the spatial light modulation subsystems, a distance S1 between the spatial light modulator and the first lens group is smaller than a focal length f1 of the first lens group.

7. The holographic near-to-eye display system of claim 1, in any of the spatial light modulation subsystems, the stop is located on a fourier transform surface of the first lens group.

8. The holographic near-to-eye display system of claim 1, wherein the light source is a monochromatic laser light source or a color laser light source with coherence, or the light source is a monochromatic LED light source or a color LED light source with set coherence.

9. The holographic near-eye display system of claim 1, wherein the spatial light modulator is a reflective or transmissive spatial light modulator, and the modulation is phase modulation or amplitude modulation.

10. A holographic near-to-eye display method based on multiple spatial light modulators, characterized in that the holographic near-to-eye display system based on multiple spatial light modulators of any one of claims 1 to 9 is adopted to perform holographic near-to-eye display based on multiple spatial light modulators.

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