A ghost image-eliminating diffractive optical device

Abstract

The application discloses a kind of to eliminate ghost diffraction optical equipment, including micro light machine, polarization device is built-in in micro light machine, and light waveguide mechanism is located at the light exit side of micro light machine.Utilize the zero-order diffraction order, first diffraction order and first diffraction order secondary diffraction of incident coupler, the first polarization direction light emitted by micro light machine is sequentially divided into a light, b light and c light, and b light is diffracted into waveguide plate and is coupled out to eye socket for total reflection transmission, a light and c light pass through waveguide plate, and by setting reflective quarter-wave plate, so that a light and c light in first polarization direction light are converted into second polarization direction, and the polarization direction of second polarization direction light is orthogonal to polarization device, so that a light and c light of second polarization direction are absorbed when passing through polarization device, so as to prevent from being coupled out into light waveguide mechanism again, and then eliminate ghost, so as to effectively improve the imaging quality of image in eye socket.

Description

Technical Field

[0001] This invention belongs to the field of optics, specifically relating to an optical device for eliminating ghost diffraction. Background Technology

[0002] AR (Augmented Reality), MR (Mixed Reality), and HMD (Head-Mounted Display) are wearable, transparent or semi-transparent optical devices that can be used in various fields such as gaming, entertainment, consumer electronics, education, and healthcare. Optical devices at least include a micro-optomechanical system, an incident coupler, a waveguide plate, and an output coupler. For example... Figure 1 As shown, a micro-optical engine generally includes a light source, a polarizing beam splitter, a micro-display screen, and an imaging lens. The light emitted by the light source passes through the prism (which is a polarizing beam splitter, transmitting P-polarized light and reflecting S-polarized light) and is reflected in the S-polarized state to the micro-display screen. After passing through the micro-display screen, it exits in the P-polarized state and reaches the imaging lens, generating a high-quality image of a certain size. Then, through the incident coupler, it is coupled into the waveguide plate in the first diffraction order for total internal reflection transmission. Finally, through the output coupler, the image is copied and coupled out to the eye socket, so that the desired image can be received in the eye socket.

[0003] However, in existing technologies, the output light from micro-optomechanical systems, when passing through the incident coupler, such as... Figure 2 As shown, the first diffraction order (solid line) is reflected by the waveguide plate and interacts with the incident coupler again, resulting in a second diffraction of the first diffraction order (dashed line). The generated light is coupled out from the incident coupler and enters the micro display screen. After being reflected by the micro display screen, its polarization state changes from P to S and interacts with the incident coupler again. After entering the waveguide plate, it undergoes total internal reflection and is replicated through the output coupler and finally coupled out into the eye socket, forming the first ghost image and affecting the imaging quality of the desired image.

[0004] In addition, such as Figure 3 As shown, when the light output from the micro-optical engine passes through the incident coupler, since the incident coupler generally uses diffractive optical elements, such as surface relief gratings (SRGs) or holographic gratings, it is impossible to achieve 100% efficiency in the first diffraction order. Therefore, in addition to generating the desired first diffraction order, there is also a more efficient zero-order non-diffractive light. After passing through the incident coupler, it will not change direction. After being reflected by the waveguide plate (specular reflection), it will pass through the incident coupler again and reach the micro-display screen (dashed line). After being reflected by the micro-display screen, it will undergo deflection conversion, changing from P polarization state to S polarization state, and then be diffracted again by the incident coupler. The resulting first diffraction order (dashed line) is transmitted through total internal reflection by the waveguide plate, and then copied through the output coupler and coupled out to the human eye, forming a second ghost image. The first ghost image, the second ghost image, and the desired image are superimposed, reducing the imaging quality in the eye socket. Summary of the Invention

[0005] The present application aims at providing a ghost image eliminating diffractive optical device to solve the problems in the background art.

[0006] To achieve the above-mentioned purpose, the present application adopts the technical scheme of:

[0007] The present application provides a ghost image eliminating diffractive optical device, which comprises a micro light machine, a polarization device built-in the micro light machine, and a light waveguide mechanism located at the light emitting side of the micro light machine.

[0008] The light waveguide mechanism comprises an incident coupler, a waveguide plate, a reflective quarter-wave plate, and an output coupler, the incident coupler, the reflective quarter-wave plate, and the output coupler are all arranged on the waveguide plate, the incident coupler and the reflective quarter-wave plate are oppositely arranged, the incident coupler and the output coupler are located on the same side of the waveguide plate, and the output coupler is used for transmitting the light transmitted by the waveguide plate to the eye.

[0009] The polarization device is located on the side of the incident coupler away from the waveguide plate, and is used for transmitting the first polarization direction light emitted by the micro light machine to the incident coupler, the incident coupler uses the zero-order diffraction order, the first diffraction order, and the second diffraction of the first diffraction order to sequentially divide the first polarization direction light into a light ray a, a light ray b, and a light ray c, and the polarization directions of the light rays a, b, and c are consistent with the first polarization direction, the incident coupler uses the first diffraction order to diffract the light ray b to the waveguide plate for total reflection transmission, and the light ray b is coupled out to the human eye by the output coupler, the incident coupler uses the zero-order diffraction order and the second diffraction of the first diffraction order to respectively transmit the light rays a and c through the waveguide plate to the reflective quarter-wave plate, the reflective quarter-wave plate converts the first polarization direction of the light rays a and c to a second polarization direction and reflects them to the polarization device, and the second polarization direction is orthogonal to the first polarization direction, so that the light rays a and c of the second polarization direction are absorbed by the polarization device, preventing the light rays a and c from being coupled out to the human eye again in the light waveguide mechanism, and thus eliminating the ghost image.

[0010] Preferably, the micro light machine further comprises a light emitting source, an illumination assembly, a micro display screen, a prism, and an imaging lens, the imaging lens, the prism, and the micro display screen are sequentially arranged, and the imaging lens is arranged close to the light waveguide mechanism, the polarization device is located between any two of the incident coupler, the imaging lens, and the prism, the light emitting source is located on one side of the prism, and the optical axis is perpendicular to the optical axis of the micro display screen, and the illumination assembly is located between the light emitting source and the prism.

[0011] Preferably, the illumination assembly comprises a collimating optical element, a uniform light optical element, and a relay optical element which are sequentially and side by side arranged from the light emitting source to the prism.

[0012] Preferably, the micro display screen is an LCOS display screen, the prism is a polarization beam splitter, the polarization device is located between the prism and the imaging lens, and the polarization device is a polarizer.

[0013] Preferably, the micro display screen is a DLP display screen, the prism is composed of two right-angled triangular prisms, and the inclined surfaces of the two right-angled triangular prisms are attached to each other, the polarization device is located between the incoupler and the imaging lens or between the imaging lens and the prism, and the polarization device is a polarizer.

[0014] Preferably, the micro display screen is a Micro-LEDs or Micro-OLEDs display screen, the prism is an X prism composed of four triangular prisms, and a film layer for transmitting or reflecting light of different wavelengths is coated between each pair of contacting triangular prisms, the polarization device is located between the incoupler and the imaging lens or between the imaging lens and the prism, and the polarization device is a polarizer or a polarizer.

[0015] Preferably, the fast axis of the reflective quarter-wave plate forms an angle of 45° with the first polarization direction.

[0016] Preferably, the reflective quarter-wave plate is an achromatic reflective quarter-wave plate.

[0017] Preferably, the light source is an LED light source, a Micro-LED light source, a laser light source, or an OLED light source.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The optical device utilizes the zeroth diffraction order, the first diffraction order, and the second diffraction of the first diffraction order of the incoupler to sequentially divide the light of the first polarization direction emitted by the micro light machine into a light, a light, and a light, the light is diffracted into the waveguide plate for total reflection transmission and coupled out to the eyebox, the light and the light pass through the waveguide plate, and the reflective quarter-wave plate is arranged to convert the light and the light in the first polarization direction into a second polarization direction, and the light of the second polarization direction is orthogonal to the polarization direction of the polarization device, so that the light and the light of the second polarization direction are absorbed when passing through the polarization device, thereby preventing re-entry into the optical waveguide mechanism and being coupled out, and thus eliminating ghost images, thereby effectively improving the imaging quality of the image in the eyebox. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a first schematic diagram of the optical device structure in the prior art.

[0021] Figure 2 It is a second schematic diagram of the optical device structure in the prior art.

[0022] Figure 3A third schematic diagram of the structure of the optical device in the prior art;

[0023] Figure 4 A schematic diagram of the structure of the ghost image eliminating diffractive optical device of the present application;

[0024] Figure 5 A case of the polarization state conversion of the reflective quarter-wave plate in the present application;

[0025] Figure 6 Another case of the polarization state conversion of the reflective quarter-wave plate in the present application;

[0026] Figure 7 A schematic diagram of the X prism in the present application.

[0027] Legend: 1, micro light machine; 11, light source; 12, micro display screen; 13, prism; 14, imaging lens; 15, illumination assembly; 2, optical waveguide mechanism; 21, incoupler; 22, waveguide plate; 23, reflective quarter-wave plate; 24, outcoupler; 3, eyebox; 4, polarization device. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0029] It should be noted that when an assembly is referred to as being "connected" to another assembly, it can be directly connected to the other assembly or there can be a middle assembly. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments of the present application and are not intended to limit the present application.

[0030] As Figures 4-7 shown, a ghost image eliminating diffractive optical device includes a micro light machine 1, the micro light machine 1 is internally provided with a polarization device 4, and an optical waveguide mechanism 2 is located at the light exit side of the micro light machine 1, wherein:

[0031] The optical waveguide mechanism 2 includes an incident coupler 21, a waveguide plate 22, a reflective quarter-wave plate 23, and an output coupler 24. The incident coupler 21, the reflective quarter-wave plate 23, and the output coupler 24 are all attached to the waveguide plate 22, and the incident coupler 21 and the reflective quarter-wave plate 23 are arranged opposite to each other. The incident coupler 21 and the output coupler 24 are located on the same side of the waveguide plate 22. The output coupler 24 is used to direct the light transmitted by the waveguide plate 22 into the eye socket 3.

[0032] Polarizing device 4, located on the side of the incident coupler 21 away from the waveguide plate 22, is used to guide the first polarized light emitted by the micro-optomechanical system 1 through the incident coupler 21. The incident coupler 21 uses zero-order diffraction, first diffraction, and second diffraction of the first diffraction order to sequentially divide the first polarized light into ray a, ray b, and ray c, and the polarization directions of ray a, ray b, and ray c are consistent with the first polarization direction. The incident coupler 21 uses the first diffraction order to diffract ray b into the waveguide plate 22 for total internal reflection transmission, and then outputs it through the output coupler 24. The light rays are coupled out to the eye socket 3. The incident coupler 21 uses the zeroth order diffraction order and the second diffraction order of the first order to send the a-ray and c-ray through the waveguide plate 22 to the reflective quarter-wave plate 23. The reflective quarter-wave plate 23 converts the first polarization direction of the a-ray and c-ray to the second polarization direction and reflects them to the polarization device 4. The second polarization direction is orthogonal to the first polarization direction, so that the a-ray and c-ray in the second polarization direction are absorbed by the polarization device 4, preventing the a-ray and c-ray from re-entering the optical waveguide mechanism 2 and being coupled out to the eye socket 3, thereby eliminating the ghost image.

[0033] Specifically, with Figure 4 For example, the incident coupler 21 is bonded to the lower surface of the waveguide plate 22, the reflecting quarter-wave plate 23 is bonded to the upper surface of the waveguide plate 22, and the incident coupler 21 and the reflecting quarter-wave plate 23 are located at the left end of the micro-optomechanical unit 1. The output coupler 24 is bonded to the lower surface of the waveguide plate 22 and is close to the right end of the waveguide plate 22. The micro-optomechanical unit 1 is located below the incident coupler 21, and the polarization device 4 is located below the incident coupler 21. Figure 4 (This is one example.) The eye socket 3 is located below the output coupler 24. The above orientation is for descriptive purposes only and is not a specific limitation. The first polarization direction light can be either P-polarized or S-polarized. If the first polarization direction light is P-polarized, then the second polarization direction is S-polarized; if the first polarization direction light is S-polarized, then the second polarization direction is P-polarized. Figure 4 The dashed arrow indicates the second polarization direction.

[0034] In one embodiment, the micro-light machine 1 further comprises a light source 11, an illumination assembly 15, a micro-display screen 12, a prism 13 and an imaging lens 14, the imaging lens 14, the prism 13 and the micro-display screen 12 are sequentially arranged, and the imaging lens 14 is arranged close to the light waveguide mechanism 2, the polarizing device 4 is located between any two of the incoupler 21, the imaging lens 14 and the prism 13, the light source 11 is located on one side of the prism 13, and the optical axis is perpendicular to the optical axis of the micro-display screen 12, and the illumination assembly 15 is located between the light source 11 and the prism 13.

[0035] Specifically, the light source 11, the illumination assembly 15 and the prism 13 are sequentially arranged from left to right, the micro-display screen 12 is located below the prism 13, and the imaging lens 14 is located above the prism 13 and below the incoupler 21. The imaging lens 14 comprises a plurality of lenses, each of which can be a plane mirror, an aspherical lens or a spherical lens. According to the type of the micro-display screen 12, the position of the polarizing device 4 is different.

[0036] In one embodiment, the illumination assembly 15 comprises a collimating optical element, a uniform optical element and a relay optical element sequentially arranged from the light source 11 to the prism 13.

[0037] Specifically, the collimating optical element, the uniform optical element and the relay optical element are sequentially arranged from left to right, the collimating optical element is used for collimating light rays and can be composed of a single or multiple spherical lenses or a single or multiple aspherical lenses, the uniform optical element is used for uniformizing light rays and can be a microlens array or a diffusion sheet, and the relay optical element is used for modulating light rays and can be composed of a plurality of spherical lenses or a plurality of aspherical lenses.

[0038] In one embodiment, the micro-display screen 12 is an LCOS display screen, the prism 13 is a polarization beam splitter, the polarizing device 4 is located between the prism 13 and the imaging lens 14, and the polarizing device 4 is a polarimeter.

[0039] Specifically, the polarization beam splitter prism is generally formed by gluing or optical gluing the hypotenuse of two right-angle prisms, and a polarization beam splitting film is coated on the hypotenuse. The first polarization direction light output by the micro light machine 1 can be P polarization direction light or S polarization direction light. Assuming that the first polarization direction light is P polarization direction light, a P polarization direction polarizer is used between the prism 13 and the imaging lens 14, so that the P polarization direction light passes through, and the polarization directions of the a light, the b light and the c light are also P polarization direction. The incidence coupler 21 diffracts the b light into the waveguide plate 22 by using the first diffraction order for total reflection transmission, and the b light is coupled out of the waveguide plate 22 by the output coupler 24 to the eyebox 3. The incidence coupler 21 diffracts the a light and the c light through the waveguide plate 22 by using the zero-order diffraction order and the first diffraction order twice, respectively, to the reflective quarter-wave plate 23. The reflective quarter-wave plate 23 converts the P polarization direction of the a light and the c light into S polarization direction and reflects it to the polarization device 4. The S polarization direction is orthogonal to the P polarization direction of the polarizer, so that the a light and the c light of the second polarization direction are absorbed by the polarization device 4, preventing the a light and the c light from being coupled out of the light waveguide mechanism 2 to the eyebox 3 again, thereby eliminating ghost images.

[0040] In one embodiment, the micro display screen 12 is a DLP display screen, the prism 13 is composed of two right-angle triangular prisms, and the hypotenuses of the two right-angle triangular prisms are attached to each other. The polarization device 4 is located between the incidence coupler 21 and the imaging lens 14 or between the imaging lens 14 and the prism 13. The polarization device 4 is a polarizer.

[0041] Specifically, the prism 13 can be composed of two right-angle triangular prisms, and the right-angle triangular prisms can also be non-right-angle triangular prisms, and there is no film coating between the two triangular prisms. The polarization device 4 can be located at any position between the incidence coupler 21 and the imaging lens 14 or at any position between the imaging lens 14 and the prism 13. Assuming that the first polarization direction light output by the micro light machine 1 is S polarization direction light, the polarizer is an S polarization direction polarizer, so that the S polarization direction light passes through, and the polarization directions of the a light, the b light and the c light are also S polarization direction. The incidence coupler 21 diffracts the b light into the waveguide plate 22 by using the first diffraction order for total reflection transmission, and the b light is coupled out of the waveguide plate 22 by the output coupler 24 to the eyebox 3. The incidence coupler 21 diffracts the a light and the c light through the waveguide plate 22 by using the zero-order diffraction order and the first diffraction order twice, respectively, to the reflective quarter-wave plate 23. The reflective quarter-wave plate 23 converts the S polarization direction of the a light and the c light into P polarization direction and reflects it to the polarization device 4. The P polarization direction is orthogonal to the S polarization direction of the polarizer, so that the a light and the c light of the P polarization direction are absorbed by the polarization device 4, preventing the a light and the c light from being coupled out of the light waveguide mechanism 2 to the eyebox 3 again, thereby eliminating ghost images.

[0042] In one embodiment, the micro display screen 12 is a Micro-LEDs or Micro-OLEDs display screen, the prism 13 is an X prism, the X prism is composed of four triangular prisms, and a film layer for realizing light transmission or reflection of different wavelengths is coated between each contacting two triangular prisms, and the polarizing device 4 is located between the incoupler 21 and the imaging lens 14 or between the imaging lens 14 and the prism 13, and the polarizing device 4 is a polarizer or an analyzer.

[0043] Specifically, as shown in Figure 7 The X prism is shown, wherein A, B, C, and D represent the film layers coated between the contacting two triangular prisms, for example, the A and C film layers reflect blue light and transmit green and red light, and the B and D film layers reflect red light and transmit green and blue light, and the X prism realizes the effect of combining multi-color light. The polarizing device 4 can be placed alone or bonded on the upper surface of the prism 13 or the upper surface of a certain lens with a planar surface in the imaging lens 14 to save space. Assuming that the first polarized direction light output by the micro light machine 1 is S polarized direction light, the polarizer or the analyzer is an S polarized direction polarizer or analyzer, so that the S polarized direction light passes through, and the polarization directions of the a light, the b light, and the c light are also S polarized direction, the incoupler 21 diffracts the b light into the waveguide plate 22 for total reflection transmission by using the first diffraction order, and the b light is coupled out to the eyebox 3 by the outcoupler 24, the incoupler 21 diffracts the a light and the c light to pass through the waveguide plate 22 by using the zero-order diffraction order and the first diffraction order respectively, the a light and the c light are reflected to the polarizing device 4 by the reflective quarter-wave plate 23, the S polarized direction of the a light and the c light is converted to the P polarized direction, and the P polarized direction is orthogonal to the S polarized direction of the polarizer or the analyzer, so that the P polarized direction a light and the c light are absorbed by the polarizing device 4, preventing the a light and the c light from entering the light waveguide mechanism 2 again and being coupled out to the eyebox 3, thereby eliminating ghost images.

[0044] In one embodiment, the angle between the fast axis of the reflective quarter-wave plate 23 and the first polarized direction light is 45°.

[0045] In one embodiment, the reflective quarter-wave plate 23 is an achromatic reflective quarter-wave plate.

[0046] Specifically, the achromatic reflective quarter-wave plate is composed of two different birefringent crystal materials, so that the phase retardation difference in the required visible light wavelength range of 400 nm-700 nm can be offset by the above two materials, so that all phase retardations in the wavelength range are one-quarter wavelength. As shown in Figure 5 and 6As shown (P represents P-polarization direction light, and S represents S-polarization direction light), if the light incident to the reflective quarter-wave plate 23 is P-polarization direction light, the reflected light is S-polarization direction light; if the light incident to the reflective quarter-wave plate 23 is S-polarization direction light, the reflected light is P-polarization direction light. At the same time, the width of the reflective quarter-wave plate 23 along the left-right direction is greater than or equal to the width of the incoupler 21 along the left-right direction.

[0047] In one embodiment, the light-emitting source 11 is an LED light source, a Micro-LED light source, a laser light source, or an OLED light source.

[0048] The optical device uses the zero-order diffraction order, the first-order diffraction order, and the second-order diffraction of the incoupler to sequentially divide the first polarization direction light emitted by the micro light machine into a light ray a, a light ray b, and a light ray c, and the light ray b is diffracted into the waveguide plate for total reflection transmission and coupling out to the eyebox, the light rays a and c pass through the waveguide plate, and by setting the reflective quarter-wave plate, the light rays a and c in the first polarization direction light are converted into a second polarization direction, and the second polarization direction light is orthogonal to the polarization direction of the polarizer, so that the light rays a and c in the second polarization direction are absorbed when passing through the polarizer, thereby preventing re-entry into the light waveguide mechanism and being coupled out, thereby eliminating ghost images, and thus the imaging quality of the image in the eyebox can be effectively improved.

[0049] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure.

[0050] The above-described embodiments only express the specific and detailed embodiments described in the present application, but should not be construed as limiting the scope of the patent application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.

Claims

1. An optical device for eliminating ghost diffraction, comprising a micro-optical engine (1), characterized in that: The micro-optical engine (1) has a built-in polarization device (4) and an optical waveguide mechanism (2) located on the light-emitting side of the micro-optical engine (1), wherein: The optical waveguide mechanism (2) includes an incident coupler (21), a waveguide plate (22), a reflective quarter-wave plate (23), and an output coupler (24). The incident coupler (21), the reflective quarter-wave plate (23), and the output coupler (24) are all attached to the waveguide plate (22), and the incident coupler (21) and the reflective quarter-wave plate (23) are arranged opposite to each other. The incident coupler (21) and the output coupler (24) are located on the same side of the waveguide plate (22). The output coupler (24) is used to direct the light transmitted by the waveguide plate (22) into the eye socket (3). The polarization device (4) is located on the side of the incident coupler (21) away from the waveguide plate (22), and is used to guide the first polarized light emitted by the micro-optomechanical unit (1) through to the incident coupler (21). The incident coupler (21) uses zero-order diffraction, first diffraction, and second diffraction of the first diffraction order to divide the first polarized light into a ray, a ray, and a ray, respectively, and the polarization directions of the a ray, b ray, and c ray are consistent with the first polarization direction. The incident coupler (21) uses the first diffraction order to diffract the b ray into the waveguide plate (22) for total internal reflection transmission, and the output coupler (4) guides the light to the waveguide plate (22) for transmission. 24) Coupled out to the eye socket (3), the incident coupler (21) uses the zero-order diffraction order and the first diffraction order second diffraction to send the a-ray and c-ray through the waveguide plate (22) to the reflective quarter-wave plate (23). The reflective quarter-wave plate (23) converts the first polarization direction of the a-ray and c-ray to the second polarization direction and reflects them to the polarization device (4). The second polarization direction is orthogonal to the first polarization direction, so that the a-ray and c-ray in the second polarization direction are absorbed by the polarization device (4), preventing the a-ray and c-ray from re-entering the optical waveguide mechanism (2) and coupling out to the eye socket (3), thereby eliminating ghost images.

2. The optical device for eliminating ghost diffraction as described in claim 1, characterized in that: The micro-optical engine (1) further includes a light source (11), an illumination component (15), a micro-display (12), a prism (13), and an imaging lens (14). The imaging lens (14), prism (13), and micro-display (12) are arranged in sequence, and the imaging lens (14) is set close to the optical waveguide mechanism (2). The polarization device (4) is located between any two of the incident coupler (21), imaging lens (14), and prism (13). The light source (11) is located on one side of the prism (13), and its optical axis is perpendicular to the optical axis of the micro-display (12). The illumination component (15) is located between the light source (11) and the prism (13).

3. The optical device for eliminating ghost diffraction as described in claim 2, characterized in that: The lighting assembly (15) includes a collimating optical element, a uniform optical element, and a relay optical element arranged in parallel from the light source (11) to the prism (13).

4. The optical device for eliminating ghost diffraction as described in claim 2, characterized in that: The microdisplay (12) is an LCOS display screen, the prism (13) is a polarizing beam splitter, the polarizing device (4) is located between the prism (13) and the imaging lens (14), and the polarizing device (4) is an analyzer.

5. The optical device for eliminating ghost diffraction as described in claim 2, characterized in that: The micro-display screen (12) is a DLP display screen. The prism (13) is composed of two right-angled triangular prisms, and the inclined surfaces of the two right-angled triangular prisms are in contact. The polarizing device (4) is located between the incident coupler (21) and the imaging lens (14) or between the imaging lens (14) and the prism (13). The polarizing device (4) is a polarizer.

6. The optical device for eliminating ghost diffraction as described in claim 2, characterized in that: The micro-display (12) is a Micro-LEDs or Micro-OLEDs display screen, the prism (13) is an X-prism, the X-prism is composed of four triangular prisms, and a film layer is coated between each pair of contacting triangular prisms to achieve the transmission or reflection of light of different wavelengths. The polarization device (4) is located between the incident coupler (21) and the imaging lens (14) or between the imaging lens (14) and the prism (13). The polarization device (4) is an analyzer or polarizer.

7. The optical device for eliminating ghost diffraction as described in claim 1, characterized in that: The fast axis of the reflective quarter-wave plate (23) is at an angle of 45° to the direction of the first polarization light.

8. The optical device for eliminating ghost diffraction as described in claim 1, characterized in that: The reflective quarter-wave plate (23) is an achromatic reflective quarter-wave plate.

9. The optical device for eliminating ghost diffraction as described in claim 2, characterized in that: The light source (11) is an LED light source, a Micro-LED light source, a laser light source or an OLED light source.

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