CN111443487B - Portable large-visual-angle three-dimensional near-to-eye display system and method based on complex amplitude modulation - Google Patents

Abstract

There is provided a portable large-viewing angle three-dimensional near-to-eye display system based on complex amplitude modulation, comprising: the phase type spatial light modulator is loaded with two phase type sub-holograms as an original three-dimensional image; the Abbe filtering imaging system is used for reproducing three-dimensional complex amplitude information of an original three-dimensional image and carrying out first amplification imaging on the original three-dimensional image; and the concave reflector is used for receiving the three-dimensional image amplified for the first time by the Abbe filtering imaging system and carrying out amplified imaging for the second time on the three-dimensional image amplified for the first time, and the three-dimensional image amplified for the second time is superposed with the scene of the real world and then is incident to eyes. The field angle of the complex amplitude modulation type three-dimensional near-to-eye display system is amplified in two steps by adopting the Abbe filtering imaging system and the curved surface reflection structure, and the complex amplitude modulation type three-dimensional near-to-eye display system has the advantages of compact structure, small volume, light weight and the like.

Description

Portable and large viewing angle 3D near-eye display system and method based on complex amplitude modulation

technical field

The invention relates to a portable large viewing angle three-dimensional near-eye display system and method based on complex amplitude modulation, belonging to the field of three-dimensional near-eye display.

Background technique

3D near-eye display technology has been a research hotspot in the international display field in recent years. This technology provides observers with a new visual experience by superimposing artificially modulated virtual 3D signals on real-world scenes. The technology can be used in augmented reality (AR) and virtual reality (VR), and has important application prospects in military, medical, education, entertainment and other fields. Among the many schemes for realizing 3D near-eye display technology, complex amplitude modulation technology, as a kind of holographic 3D display technology, is considered to be one of the most promising technologies. In addition to the advantages of holographic 3D display that can realize continuous depth change 3D reproduction, complex amplitude modulation technology can simultaneously modulate the amplitude and phase of incident light waves, so as to completely restore the target 3D image without losing any information. More realistic 3D effects. In addition, the complex amplitude modulation technology does not need to iterate the calculation of the hologram, saves a lot of calculation time, and has the ability to realize dynamic three-dimensional display. Therefore, the complex amplitude modulation technique is very suitable for the design of 3D near-eye display system.

For example, Chinese patent CN105824128A discloses a three-dimensional augmented reality display system based on complex amplitude grating modulation, which can realize the superposition of true three-dimensional images and external real scenes. The system includes: amplitude type spatial light modulator, 4f lens system, sinusoidal grating, Phase shifter and semi-transparent mirror; amplitude-type spatial light modulator and sinusoidal grating are placed in sequence on the input focal plane and spectral plane of the 4f lens system, the phase shifter is placed close to the amplitude-type spatial light modulator, and the semi-transparent and semi-reflective The mirror is placed at a certain distance behind the output focal plane of the 4f lens system, and two holograms are loaded on the two partitions of the amplitude-based spatial light modulator. Under the irradiation of the laser, the two holograms are modulated by a sinusoidal grating in the frequency domain of the 4f lens system. , and synthesized into a target complex-amplitude wavefront at the output surface, the target complex-amplitude wavefront propagates to the half mirror and is coupled and superimposed by the half mirror into the field of view of the human eye.

However, this system has a very limited viewing angle due to display device limitations. The core device of the existing complex amplitude modulation 3D near-eye display system is a spatial light modulator. Limited by the grid structure of the spatial light modulator, and its pixel size is in the order of several micrometers, the diffraction angle of the modulated output image is small. In addition, due to the small size of the spatial light modulator panel, the existing complex amplitude The image field of view output by the modulated 3D near-eye display system is limited, which seriously affects the viewing experience. In addition, the existing complex amplitude modulation 3D near-eye display system, some solutions use dual spatial light modulators, and some solutions use 4f system for filtering, resulting in a large number of system components and large size, which do not meet the design requirements of near-eye display systems for portability and portability .

In view of the above, the present invention aims to provide a portable large viewing angle 3D near-eye display system and method based on complex amplitude modulation to solve one or more of the above technical problems.

SUMMARY OF THE INVENTION

In order to solve one or more technical problems in the prior art, according to an aspect of the present invention, a portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation is provided, which includes:

A phase-type spatial light modulator, on which two phase-type sub-holograms are loaded as original three-dimensional images;

An Abbe filter imaging system for reproducing the 3D complex amplitude information of the original 3D image and performing the first magnification imaging of the original 3D image; and

The concave mirror is used to receive the 3D image after the first magnification of the Abbe filter imaging system and perform the second magnification imaging on the 3D image after the first magnification, and the 3D image after the second magnification is consistent with the real world. The scene is superimposed and incident to the eye.

According to yet another aspect of the present invention, an Abbe filter imaging system includes a convex lens and a sinusoidal grating on a back focal plane of the convex lens.

According to yet another aspect of the present invention, an Abbe-filtered imaging system includes a doublet and a sinusoidal grating on a back focal plane of the doublet.

According to yet another aspect of the present invention, the portable large viewing angle 3D near-eye display system based on complex amplitude modulation further includes a half mirror arranged between the Abbe filter imaging system and the concave mirror, for reflecting the concave surface The three-dimensional image magnified by the mirror is reflected to the eye, and the real-world scene is directly transmitted into the eye through the half mirror.

According to yet another aspect of the present invention, the concave mirror is arranged in an off-axis manner with respect to the optical axis of the phase-type spatial light modulator and the Abbe filter imaging system, and the three-dimensional image magnified by the concave mirror is different from the real world scene. directly into the eyes.

According to yet another aspect of the present invention, the concave mirror is a concave half mirror, which is used to perform a second magnification imaging on the three-dimensional image after the first magnification, and the three-dimensional image after the second magnification is directly Incident to the eye, the real-world scene enters the eye through this concave half mirror.

According to yet another aspect of the present invention, the portable large viewing angle 3D near-eye display system based on complex amplitude modulation further comprises a semi-transparent mirror located on the optical path between the Abbe filter imaging system and the concave mirror, the semi-transparent and semi-transparent mirror The mirror is used to reflect the first-amplified three-dimensional image of the Abbe filter imaging system to a concave mirror, and the concave mirror is a concave half-mirror and is used to perform the first-amplified three-dimensional image. The second magnification imaging, the second magnified three-dimensional image is transmitted to the eye after being transmitted by the half mirror, and the real world scene is sequentially transmitted through the concave half mirror and the half mirror. into the eyes behind the mirror.

According to yet another aspect of the present invention, the phase-based spatial light modulator is a transmission type or a reflection type.

According to yet another aspect of the present invention, two phase-type sub-holograms are loaded on the phase-type spatial light modulator with a certain interval.

According to another aspect of the present invention, there is also provided a method for displaying using the aforementioned portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation, which is characterized by comprising the following steps:

Reproduce the three-dimensional complex amplitude information of the original three-dimensional image, and perform the first magnification imaging of the original three-dimensional image;

Perform a second magnification imaging on the 3D image after the first magnification;

The 3D image after the second magnification is superimposed with the real-world scene and then incident on the eye.

Compared with the prior art, the present invention has one or more of the following technical effects:

The Abbe filter imaging system and the curved surface reflection structure are used to realize the two-step (secondary) magnification of the field of view of the complex amplitude modulation 3D near-eye display system. At the same time, it has the advantages of compact structure, small size and light weight. In comparison, the number of optical components is reduced and the complexity of the system is reduced.

Description of drawings

In order to be able to understand the details of the above-described features of the present invention, reference may be made to the examples for a more detailed description of the invention briefly summarized above. The accompanying drawings relate to preferred embodiments of the present invention and are described as follows:

1 is a schematic structural diagram of a portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation according to a first preferred embodiment of the present invention;

2 is a schematic structural diagram of a portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation according to a second preferred embodiment of the present invention;

3 is a schematic structural diagram of a portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation according to a third preferred embodiment of the present invention;

4 is a schematic structural diagram of a portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation according to a fourth preferred embodiment of the present invention;

5 is a schematic structural diagram of a portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation according to a fifth preferred embodiment of the present invention.

specific embodiment

Various embodiments will now be described in detail, one or more examples of which are illustrated in the figures. The various examples are offered by way of explanation and not by way of limitation. For example, features illustrated or described as part of one embodiment can be used in or in conjunction with any other embodiment to yield yet another embodiment. The present invention is intended to encompass such modifications and variations.

In the following description of the drawings, the same reference numerals refer to the same or similar structures. Generally, only the differences of individual embodiments will be described. Unless explicitly stated otherwise, descriptions of parts or aspects in one embodiment can also be applied to corresponding parts or aspects in another embodiment.

Example 1

Referring to FIG. 2 , it shows a schematic structural diagram of a portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation according to a preferred embodiment of the present invention. The portable large viewing angle 3D near-eye display system based on complex amplitude modulation may include:

The phase-type spatial light modulator 1, on which two phase-type sub-holograms 201 and 202 are loaded as original three-dimensional images;

An Abbe filter imaging system for reproducing the 3D complex amplitude information of the original 3D image and performing the first magnification imaging of the original 3D image; and

The concave mirror 5 is used to receive the first-amplified three-dimensional image of the Abbe filter imaging system and perform second-time magnification imaging on the first-amplified three-dimensional image, and the second-time enlarged three-dimensional image is the same as the real Scene 8 of the world is superimposed and incident to eye 7. It can be understood that the present invention realizes the enlargement of the field of view of the three-dimensional near-eye display system.

According to a preferred embodiment of the present invention, referring to FIGS. 1-4 , the Abbe filter imaging system includes a convex lens 3 and a sinusoidal grating 4 located on the back focal plane of the convex lens 3 . By placing a sinusoidal grating 4 on the rear focal plane of the lens, the phase-type sub-holograms 201 and 202 on the spatial light modulator can be modulated.

According to a preferred embodiment of the present invention, referring to FIG. 5 , the Abbe filter imaging system includes a doublet lens 10 and a sinusoidal grating 4 on the back focal plane of the doublet lens 10 .

According to a preferred embodiment of the present invention, referring to FIG. 1 , the portable large viewing angle 3D near-eye display system based on complex amplitude modulation further includes a transflector arranged between the Abbe filter imaging system and the concave mirror 5 The mirror 6 is used to reflect the three-dimensional image enlarged by the concave mirror 5 to the eye 7 , and the real world scene 8 is directly transmitted into the eye 7 through the half mirror 6 .

According to a preferred embodiment of the present invention, referring to FIG. 2 , the concave mirror 5 is arranged in an off-axis manner with respect to the optical axis of the phase-type spatial light modulator 1 and the Abbe filter imaging system, and the concave mirror 5 is enlarged After the 3D image and the real world scene 8 go directly to the eye 7 .

According to a preferred embodiment of the present invention, referring to FIG. 3 , the concave mirror is a concave half mirror 9, which is used to perform a second magnification imaging on the three-dimensional image after the first magnification. The sub-magnified three-dimensional image is directly incident on the eye 7 , and the real-world scene 8 enters the eye 7 through the concave half mirror 9 .

According to a preferred embodiment of the present invention, referring to FIG. 4 , the portable large viewing angle 3D near-eye display system based on complex amplitude modulation further includes a transflector located on the optical path between the Abbe filter imaging system and the concave mirror Mirror 6, the half mirror 6 is used to reflect the three-dimensional image amplified by the Abbe filter imaging system for the first time to a concave mirror, and the concave mirror is a concave half mirror 9 and is used for said The 3D image after the first magnification is subjected to a second magnification imaging. The 3D image after the second magnification is transmitted through the half mirror 6 and then incident on the eye 7, and the real world scene 8 sequentially passes through the concave surface The half mirror 9 and the half mirror 6 then enter the eye 7 .

According to a preferred embodiment of the present invention, the phase-type spatial light modulator 1 is a transmission type or a reflection type.

According to a preferred embodiment of the present invention, two phase-type sub-holograms 201 and 202 are loaded on the phase-type spatial light modulator 1 at a certain distance.

According to a preferred embodiment of the present invention, it is assumed that the expression of a complex hologram of a three-dimensional object to be displayed is H=Aexp(iθ)

是虚数单位；该复全息图能够分解为两个位相型子全息图相加的形式：where A and θ represent the amplitude and phase of the complex hologram, respectively,

is the imaginary unit; the complex hologram can be decomposed into the form of the addition of two phase-type sub-holograms:

exp(iθ ₁ )+exp(iθ ₂ )=Aexp(iθ)

where θ ₁ and θ ₂ represent two phase-type sub-holograms, respectively. After derivation, we can get:

时，在阿贝滤波成像系统的成像面上会再现原始三维图像的三维复振幅信息，式中λ为照明光波长，f为凸透镜的焦距；When the distance d separating the two sub-holograms and the sinusoidal grating period constant Λ satisfy the formula:

When , the three-dimensional complex amplitude information of the original three-dimensional image will be reproduced on the imaging surface of the Abbe filter imaging system, where λ is the wavelength of the illumination light, and f is the focal length of the convex lens;

For the two phase-type sub-holograms, set the diffraction distance to a negative value to make the original three-dimensional image diffracted into a virtual image.

According to a preferred embodiment of the present invention, there is also provided a method for displaying using the aforementioned portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation, which includes the following steps:

Reproduce the three-dimensional complex amplitude information of the original three-dimensional image, and perform the first magnification imaging of the original three-dimensional image;

Perform a second magnification imaging on the 3D image after the first magnification;

The three-dimensional image after the second magnification is superimposed on the real-world scene 8 and then incident on the eye 7 .

The main technical principle of the present invention is that: the Abbe filter imaging system used in the present invention can realize complex amplitude reproduction of three-dimensional signals on the one hand, and improve the image quality; On the one hand, the curved reflective structure (concave mirror) can realize the optical characteristics of a convex lens and enlarge the image of the input image. On the other hand, the reflective structure can fold the optical path, which further reduces the size of the system and makes the system more compact and lightweight.

According to a preferred embodiment of the present invention, referring to FIG. 1 again, the portable large viewing angle three-dimensional near-eye display system based on complex amplitude modulation includes a phase-type spatial light modulator 1 , two phase-type sub-holograms 201 and 201 , and a convex lens 3 , sinusoidal grating 4 , concave mirror 5 and half mirror half mirror 6 . Spatial light modulators can be either transmissive or reflective. The phase-type spatial light modulator 1 is loaded with two phase-type sub-holograms as a three-dimensional image source. Suppose a complex hologram expression of a three-dimensional object to be displayed is H=Aexp(iθ)

是虚数单位。该复振幅信号能够分解为两个位相型子全息图相加的形式：where A and θ represent the amplitude and phase of the complex hologram, respectively,

is an imaginary unit. The complex amplitude signal can be decomposed into the form of the addition of two phase-type sub-holograms:

exp(iθ ₁ )+exp(iθ ₂ )=Aexp(iθ)

where θ ₁ and θ ₂ represent two phase-type sub-holograms, respectively. After deduction, we can get:

时，在阿贝滤波成像系统的成像面上会再现出待显示信号的三维复振幅信息。式中λ为照明光波长，f为凸透镜的焦距。Two phase-type sub-holograms are loaded on the phase-type spatial light modulator with a certain distance interval d. An Abbe filter imaging system is placed after the spatial light modulator. The Abbe filter imaging system includes, for example, a convex lens 3 and a sinusoidal grating 4 . The sinusoidal grating 4 is placed on the back focal plane of the convex lens 3 . When the distance d separating the two sub-holograms and the sinusoidal grating period constant Λ satisfy the formula:

, the three-dimensional complex amplitude information of the signal to be displayed will be reproduced on the imaging surface of the Abbe filter imaging system. where λ is the wavelength of the illumination light, and f is the focal length of the convex lens.

For the two phase-type sub-holograms, the diffraction distance can be set to a negative value, so that the original three-dimensional image diffraction becomes a virtual image (the left side of the spatial light modulator in Figure 1). Adjust the position of the convex lens so that the original 3D image is located outside the double focal length of the convex lens, and close to the double focal length. According to the lens imaging principle, the original image will become an inverted magnified real image outside the double focal length of the convex lens, realizing the 3D image. The first step(s) is zoomed in. The light passing through the Abbe imaging system is irradiated on the concave mirror 5, and by adjusting the position of the concave mirror, the image enlarged in the first step is located within one focal length of the concave mirror. According to the imaging principle of the concave mirror, an upright magnified virtual image will be formed on the side of the concave mirror (right side of Figure 1) to realize the second step (secondary) magnification of the three-dimensional image. The half mirror half mirror 6 is placed close to the concave mirror, and reflects the virtual image formed by the concave mirror to the human eye 7, so that the human eye can observe the enlarged virtual image. At the same time, the scene 8 of the real world scene is directly transmitted into the human eye through the semi-reflective semi-lens, so that the human eye can observe the superimposed effect.

According to a preferred embodiment of the present invention, referring to FIG. 2 , compared with the solution in FIG. 1 , the difference is that the solution uses the off-axis reflection solution of the concave mirror 5 . The semi-reflective semi-mirror in scheme 1 is canceled at the place where the human eye observes. By adjusting the angle of the concave reflector, the image reflected by the concave reflector can directly enter the human eye. The optical path of the preceding section is the same as that of the solution in FIG. 1 , and will not be repeated here.

According to a preferred embodiment of the present invention, referring to FIG. 3 , compared with the solution in FIG. 1 , the difference lies in that the combination of the semi-reflective semi-mirror and the curved mirror where the human eye observes is replaced by a concave semi-reflective semi-mirror 9 , Its reflective surface is a curved surface (concave surface), which can achieve the same optical performance as a concave mirror and perform a second magnification of the three-dimensional image. At the same time, the scene of the external world in front can enter the human eye through the concave semi-reflective semi-mirror 9, so as to realize the near-eye display in which the virtual three-dimensional image is superimposed on the real scene. The concave semi-reflective semi-mirror 9 uses an off-axis reflection scheme with 45° incidence, and the optical path of the front section is the same as the scheme in FIG. 1 , and will not be repeated here.

According to a preferred embodiment of the present invention, referring to FIG. 4 , compared with the solution in FIG. 1 , the difference lies in that this solution uses the same concave semi-reflective semi-mirror 9 as in the solution in FIG. 3 , the concave semi-reflective semi-mirror 9 Placed before the human eye, the light passing through the Abbe imaging system is first reflected by the half mirror 6 to the front surface of the concave half mirror 9, and its front surface is a curved (concave) reflective surface, which can be achieved the same as the concave mirror. The optical performance of the 3D image is a second magnification. The magnified image is transmitted into the human eye through the semi-reflective semi-mirror 6 . At the same time, the scene 8 of the external world in front can enter the human eye through the concave half mirror 9 and the half mirror 6, so as to realize the near-eye display in which the virtual three-dimensional image is superimposed on the real scene. In this scheme, the concave semi-reflective semi-mirror 9 uses a normal incidence coaxial reflection scheme, and the optical path of the front section is the same as that of the scheme in FIG. 1 , and details are not repeated here.

According to a preferred embodiment of the present invention, referring to FIG. 5 , compared with the solution in FIG. 1 , the difference is that a doublet lens 10 is used. When the image displayed by the system is a color three-dimensional image, the doublet lens 10 can well correct the chromatic aberration, so that the system can achieve a better color three-dimensional display effect. The other optical paths of the system are the same as those of the solution in FIG. 1 , and are not repeated here.

Compared with the prior art, the present invention has one or more of the following technical effects:

The Abbe filter imaging system and the curved surface reflection structure are used to realize the two-step (secondary) magnification of the field of view of the complex amplitude modulation 3D near-eye display system. At the same time, it has the advantages of compact structure, small size and light weight. In comparison, the number of optical components is reduced and the complexity of the system is reduced.

While the foregoing has been directed to embodiments of the present invention, other and further embodiments of the present invention can be devised without departing from the essential scope of the present invention, which is determined by the appended claims.

The above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention, and technical features that do not contradict each other in these embodiments can be combined with each other. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. A portable large-view-angle three-dimensional near-to-eye display system based on complex amplitude modulation is characterized by comprising the following components:

the phase type spatial light modulator is loaded with two phase type sub-holograms as an original three-dimensional image;

the Abbe filtering imaging system is used for reproducing three-dimensional complex amplitude information of an original three-dimensional image and carrying out first amplification imaging on the original three-dimensional image;

the concave reflector is used for receiving the three-dimensional image amplified for the first time by the Abbe filtering imaging system and carrying out amplification imaging for the second time on the three-dimensional image amplified for the first time, and the three-dimensional image amplified for the second time is superposed with a scene of a real world and then is incident to eyes; and

the semi-transparent semi-reflecting mirror is arranged between the Abbe filtering imaging system and the concave reflecting mirror and is used for reflecting the three-dimensional image amplified by the concave reflecting mirror to eyes, and the real world scene directly penetrates through the semi-transparent semi-reflecting mirror and enters the eyes;

the abbe filtering imaging system consists of a convex lens and a sinusoidal grating positioned on the back focal plane of the convex lens, or the abbe filtering imaging system consists of a double-cemented lens and a sinusoidal grating positioned on the back focal plane of the double-cemented lens;

wherein, two phase type sub-holograms are loaded on the phase type spatial light modulator at a certain distance, and the expression of a complex hologram of a three-dimensional object to be displayed is assumed as

H＝Aexp(iθ)

Where a and theta represent the amplitude and phase of the complex hologram respectively,

is an imaginary unit; the complex hologram can be decomposed into the form of the addition of two phase type sub-holograms:

exp(iθ ₁ )+exp(iθ ₂ )＝Aexp(iθ)

wherein theta is ₁ And theta ₂ Respectively representing two phase type sub-holograms, and deriving:

when the distance d separating the two sub-holograms and the sinusoidal grating period constant Λ satisfy the formula:

when the image is displayed, the original image is reproduced on the imaging surface of the Abbe filtering imaging systemStarting three-dimensional complex amplitude information of the three-dimensional image, wherein lambda is the wavelength of illumination light, and f is the focal length of the convex lens; setting the diffraction distance of the two phase type sub-holograms to be a negative value, so that the original three-dimensional image is diffracted to form a virtual image;

the phase type spatial light modulator, the convex lens, the sinusoidal grating, the semi-transparent semi-reflecting mirror and the concave reflecting mirror are sequentially arranged along an optical axis, and the scene and eyes of the real world are respectively positioned on two sides of the optical axis; or the phase type spatial light modulator, the double-cemented lens, the sinusoidal grating, the semi-transparent semi-reflecting mirror and the concave reflecting mirror are sequentially arranged along the optical axis, and the scene and eyes of the real world are respectively positioned on two sides of the optical axis.

2. The portable large-viewing angle three-dimensional near-to-eye display system based on complex amplitude modulation of claim 1 wherein the phase-type spatial light modulator is transmissive or reflective.

3. A method for displaying by using the portable large-viewing angle three-dimensional near-to-eye display system based on complex amplitude modulation as claimed in any one of claims 1-2, characterized by comprising the following steps:

reproducing three-dimensional complex amplitude information of the original three-dimensional image, and carrying out first amplification imaging on the original three-dimensional image;

carrying out secondary amplification imaging on the three-dimensional image subjected to the primary amplification;

and superposing the three-dimensional image after the second amplification and the scene of the real world and then injecting the three-dimensional image into the eyes.

Images