Color holographic optical element, manufacturing method, manufacturing system and correction method thereof

Abstract

The present application relates to a kind of color holographic optical elements and its manufacturing method, manufacturing system and correction method, which can solve the problem of focal shift caused by wavelength inconsistency, help to improve the quality of reproduced image.The correction method of the color holographic optical element includes the following steps: adjusting the central ray incidence angle of various color recording light according to the wavelength of color recording light and the wavelength of color reproduction light, to correct the lateral focal shift of color holographic optical element in the process of image reproduction;And adjusting the edge ray incidence angle of various color recording light according to the wavelength of color recording light and the wavelength of color reproduction light, to correct the axial defocus of color holographic optical element in the process of image reproduction.

Description

Technical Field

[0001] This invention relates to the field of holographic optical element technology, and in particular to a color holographic optical element and its fabrication method, fabrication system and calibration method. Background Technology

[0002] Holographic optical elements (HOEs) are a type of volume holographic grating (VHG). They generate interference fringes through coherent light beams and record alternating bright and dark interference fringes in a photosensitive material. Based on the different morphologies of the interference fringes generated by the recorded wavefront in the photosensitive medium, they can be classified as: plane wave transmission fringes, spherical wave transmission fringes, plane wave reflection fringes, and spherical wave reflection fringes.

[0003] Currently, in near-eye display projects using laser beam scanning, a color HOE (Homo Enamellable) is typically used as an in-eye combiner to display virtual information. However, during the fabrication of a color HOE, the inability to match the recording wavelength with the reproduction wavelength inevitably introduces a focal point shift in the reproduced object, resulting in color aberration issues. For example, existing HOEs typically employ methods such as... Figure 1A The recording optical path shown is fabricated, where the wavelength of the recording light (including the reference light and the signal light) is λr, while the existing HOE reproduction optical path used in practice is as follows: Figure 1B As shown, the wavelength of the reconstructed light (including the probe light and the object light) is λp. According to the HOE image reconstruction principle, when λp = λr, the object light is focused at point O; when λp ≠ λr, the object light is focused at point O'.

[0004] However, because the light source used in the fabrication of existing HOEs is usually different from the image source used in their operation (e.g., the light source used in HOE fabrication is generally a solid-state laser, while the light source used in HOE operation is generally a semiconductor laser, and the wavelengths of the two types of lasers have inherent differences), the wavelengths of the recording light and the reproduction light cannot be made consistent, i.e., λp ≠ λr. Therefore, existing HOEs exhibit a phenomenon where the object light focal point and the signal light focal point do not coincide during image reproduction. In other words, existing HOEs inevitably introduce problems such as... Figure 1BThe focus shift problem (including lateral focus shift and axial defocus) is illustrated. Especially for color HOE, because the recording wavelength λr of different colors (e.g., red R, green G, blue B) and the corresponding reconstructed wavelength λp are not only different, but the wavelength difference (λp-λr) is also inconsistent. Therefore, color HOE exhibits varying degrees of focus shift during image reconstruction. For example, as shown in... Figure 2 As shown in the light spot distribution with the focal plane of the G object light as a cross section, there are color difference problems between the RGB object lights, namely lateral focus shift (light spots do not overlap) and axial defocus (light spot sizes are inconsistent), making it difficult to obtain high-quality image reproduction. Summary of the Invention

[0005] One advantage of this invention is that it provides a color holographic optical element and its manufacturing method, manufacturing system and correction method, which can solve the focus shift problem caused by wavelength inconsistency and help improve the quality of the reproduced image.

[0006] Another advantage of the present invention is that it provides a color holographic optical element and a method, system and correction method for manufacturing the same. In one embodiment of the present invention, the method for manufacturing the color holographic optical element can correct the chromatic aberration caused by focus shift by adjusting the incident angle of the recording light, thereby eliminating the chromatic aberration of the color holographic optical element.

[0007] Another advantage of the present invention is that it provides a color holographic optical element and a method, system and correction method for manufacturing the same. In one embodiment of the present invention, the method for manufacturing the color holographic optical element can correct the chromatic aberration caused by lateral focus shift by adjusting the incident angle of the center ray of the recording light, and correct the chromatic aberration caused by axial defocus by adjusting the incident angle of the edge ray of the recording light, so as to completely solve the chromatic aberration problem.

[0008] Another advantage of this invention is that it provides a color holographic optical element, its fabrication method, fabrication system, and calibration method, wherein, to achieve the above objectives, expensive materials or complex structures are not required. Therefore, this invention successfully and effectively provides a solution that not only offers a simple color holographic optical element, its fabrication method, fabrication system, and calibration method, but also increases the practicality and reliability of the color holographic optical element, its fabrication method, fabrication system, and calibration method.

[0009] To achieve at least one of the above-mentioned advantages or other benefits and objectives of the present invention, the present invention provides a correction method for a color holographic optical element, comprising the steps of:

[0010] Based on the wavelengths of the color recording light and the color reproduction light, the incident angles of the central rays of each color recording light are adjusted to correct the lateral focus shift of the color holographic optical element during image reproduction; and

[0011] Based on the wavelengths of the color recording light and the color reproduction light, the incident angles of the edge rays of various color recording lights are adjusted to correct the axial defocusing of the color holographic optical element during the image reproduction process.

[0012] According to one embodiment of this application, the step of adjusting the incident angle of the center rays of various color recording lights according to the wavelength of the color recording light and the wavelength of the color reproducing light to correct the lateral focus shift of the color holographic optical element during image reproduction includes the following steps:

[0013] Based on the wavelengths of the RGB reference light and the RGB probe light, the target angle of the center ray of the RGB reference light or the RGB signal light is calculated using the K-vector equation of the volume holographic grating; and

[0014] Adjust the incident angle of the center rays of the RGB reference light or RGB signal light to be equal to the target angle of the center rays of the corresponding colors, so that the RGB probe light incident at the same angle is focused along the same axis after being diffracted by the color holographic optical element to form the RGB object light.

[0015] According to one embodiment of this application, the step of adjusting the incident angle of the edge rays of various color recording lights according to the wavelength of the color recording light and the wavelength of the color reproducing light to correct the axial defocus of the color holographic optical element during the image reproduction process includes the following steps:

[0016] Based on the wavelengths of the RGB reference light and the RGB probe light, the target angles of the edge rays of the RGB reference light or the RGB signal light are calculated using the K-vector equation of the volume holographic grating; and

[0017] Adjust the incident angle of the edge rays of the RGB reference light or RGB signal light to be equal to the target angle of the edge rays of the corresponding colors, so that the RGB probe light incident at the same angle is focused in the same focal plane by the RGB object light formed by the diffraction of the color holographic optical element.

[0018] According to another aspect of this application, this application further provides a system for fabricating a color holographic optical element, comprising:

[0019] A light source projector used to project colored recording light;

[0020] A beam splitter is disposed in the projection optical path of the light source projector to split the color recording light from the light source projector into a color reference light propagating along the reference light optical path and a color signal light propagating along the signal light optical path.

[0021] A reference light modulation assembly, disposed in the reference light path of the beam splitter, is used to modulate the color reference light from the beam splitter so that the modulated color reference light is incident rearward onto the HOE substrate; and

[0022] A signal light modulation component is disposed in the signal light path of the beam splitter and is used to modulate the color signal light from the beam splitter so that the modulated color signal light is incident forward onto the HOE substrate.

[0023] The reference light modulation component or the signal light modulation component is used to adjust the incident angle of the center ray and the incident angle of the edge ray of each color light in the color reference light or the color signal light so as to be equal to the target angle of the center ray and the target angle of the edge ray of the corresponding color, so that the modulated color reference light and the modulated color signal light interfere and record on the HOE substrate to form a color holographic optical element.

[0024] According to one embodiment of this application, the reference light modulation component is located on the reflective side of the beam splitter and is used to adjust the incident angle of the center rays of various color reference lights according to the wavelength of the RGB reference light and the wavelength of the RGB reproduced light, so as to correct the lateral focus shift of the color holographic optical element during the image reproduction process; and to adjust the incident angle of the edge rays of various color reference lights, so as to correct the axial defocus of the color holographic optical element during the image reproduction process; the signal light modulation component is a converging lens located on the transmission side of the beam splitter and is used to converge the RGB signal light from the beam splitter so that the RGB signal light is imaged in front of the HOE substrate.

[0025] According to one embodiment of this application, the reference light modulation component includes a color separation component, an edge adjustment component, and a center adjustment component arranged sequentially in the reference light optical path; the color separation component is used to split the RGB reference light into R reference light, G reference light, and B reference light; the edge adjustment component is used to adjust the incident angle of the edge rays of the R reference light, the G reference light, and the B reference light to be equal to the target angle of the edge rays of the corresponding colors; the center adjustment component is used to adjust the incident angle of the center rays of the R reference light, the G reference light, and the B reference light to be equal to the target angle of the center rays of the corresponding colors.

[0026] According to one embodiment of this application, the color separation component includes a blue light separating element for reflecting blue light and transmitting red and green light, a green light separating element for reflecting green light and transmitting red light, and a red light separating element for reflecting red light, wherein the blue light separating element, the green light separating element, and the red light separating element are selectively permeable films arranged sequentially in the reference light path.

[0027] According to one embodiment of this application, the edge adjustment assembly includes a red light edge adjustment element located on the reflective side of the red light element and a green light edge adjustment element located on the reflective side of the green light element. The red light edge adjustment element is used to modulate the R reference light from the red light element so that the incident angle of the edge ray of the R reference light is adjusted to the target angle of the edge ray of the corresponding color and then propagates to the center adjustment assembly. The green light edge adjustment element is used to modulate the G reference light from the green light element so that the incident angle of the edge ray of the G reference light is adjusted to the target angle of the edge ray of the corresponding color and then propagates to the center adjustment assembly.

[0028] According to one embodiment of this application, the red light edge adjustment element and the green light edge adjustment element are positive lenses or negative lenses.

[0029] According to one embodiment of this application, the center adjustment component includes a red light center adjustment element, a green light center adjustment element, and a blue light center adjustment element. The red light center adjustment element is used to modulate the R reference light from the red light edge adjustment element so that the incident angle of the center ray of the R reference light is adjusted to the target angle of the center ray of the corresponding color before it is incident on the HOE substrate. The green light center adjustment element is used to modulate the G reference light from the green light edge adjustment element so that the incident angle of the center ray of the G reference light is adjusted to the target angle of the center ray of the corresponding color before it is incident on the HOE substrate. The blue light center adjustment element is used to modulate the B reference light from the blue light element so that the incident angle of the center ray of the B reference light is adjusted to the target angle of the center ray of the corresponding color before it is incident on the HOE substrate.

[0030] According to one embodiment of this application, the red light center adjustment element, the green light center adjustment element, and the blue light center adjustment element are planar reflectors.

[0031] According to one embodiment of this application, the reference light modulation component is a reflective element located on the reflective side of the beam splitter, used to reflect RGB reference light from the beam splitter so that the RGB reference light is incident on the front surface of the HOE substrate; the signal light modulation component is located on the transmissive side of the beam splitter, used to adjust the incident angle of the center rays of various color signal lights according to the wavelength of the RGB signal light and the wavelength of the RGB reproduced light, so as to correct the lateral focus shift of the color holographic optical element in the image reproduction process; and to adjust the incident angle of the edge rays of various color signal lights, so as to correct the axial defocus of the color holographic optical element in the image reproduction process.

[0032] According to one embodiment of this application, the signal light modulation component includes a color separation component, an edge adjustment component, a center adjustment component, and a 4f lens system arranged sequentially in the signal light path; the color separation component is used to split the RGB signal light into R signal light, G signal light, and B signal light; the edge adjustment component is used to adjust the incident angle of the edge rays of the R signal light, the G signal light, and the B signal light to be equal to the target angle of the edge rays of the corresponding colors; the center adjustment component is used to adjust the incident angle of the center rays of the R signal light, the G signal light, and the B signal light to be equal to the target angle of the center rays of the corresponding colors; the 4f lens system is used to modulate the RGB signal light adjusted by the center adjustment component so that the adjusted RGB signal light is imaged in front of the HOE substrate.

[0033] According to another aspect of this application, this application further provides a method for fabricating a color holographic optical element, comprising the steps of:

[0034] Based on the wavelength of the color recording light and the wavelength of the color reproduction light, the center ray target angle and the edge ray target angle of the reference light or signal light of various colors in the color recording light are calculated respectively using the K-vector equation of the volume holographic grating.

[0035] A modulated color reference light and a color signal light are incident on a HOE substrate, wherein the incident angle of the center ray and the incident angle of the edge ray of the modulated color reference light or color signal light are equal to the target angle of the center ray and the target angle of the edge ray of the corresponding color, respectively; and

[0036] The HOE substrate is used to record the interference information of the colored reference light and the colored signal light to form a colored holographic optical element.

[0037] According to another aspect of this application, this application further provides a color holographic optical element, which is fabricated using the fabrication system of any of the above-described color holographic optical elements. Attached Figure Description

[0038] Figure 1A A schematic diagram of the existing HOE recording optical path;

[0039] Figure 1B A schematic diagram of the existing HOE reproduction optical path;

[0040] Figure 2 A schematic diagram of the reproduction optical path of an existing color HOE;

[0041] Figure 3 This is a schematic flowchart of a correction method for a color holographic optical element according to an embodiment of the present invention;

[0042] Figure 4 A schematic flowchart of the lateral focus offset correction step in the correction method for a color holographic optical element according to the above embodiment of the present invention is shown;

[0043] Figure 5A A schematic diagram of the recording optical path is shown in the lateral focus offset correction step according to the above embodiment of the present invention;

[0044] Figure 5B A schematic diagram illustrating the principle of the reconstructed optical path in the lateral focus offset correction step according to the above embodiment of the present invention is shown;

[0045] Figure 6 A schematic flowchart of axial defocus correction in the correction method of a color holographic optical element according to the above embodiment of the present invention is shown;

[0046] Figure 7A and Figure 7B The diagrams showing the correspondence between the recording optical path and the reproduction optical path in the axial defocus correction step according to the above embodiments of the present invention are respectively illustrated.

[0047] Figure 8 A modified example of the lateral focus offset correction step in the correction method for a color holographic optical element according to the above embodiments of the present invention is shown;

[0048] Figure 9 A modified example of axial defocus correction in the correction method for a color holographic optical element according to the above embodiments of the present invention is shown;

[0049] Figure 10 This diagram illustrates the principle of the recording optical path in the correction method for a color holographic optical element according to the above-described modified example of this application.

[0050] Figure 11 This is a block diagram of a system for fabricating a color holographic optical element according to an embodiment of the present invention;

[0051] Figure 12A first example of a system for fabricating a color holographic optical element according to the above embodiments of the present invention is shown;

[0052] Figure 13 A second example of a system for fabricating a color holographic optical element according to the above embodiments of the present invention is shown;

[0053] Figure 14 This is a schematic diagram of the reconstruction optical path of a color holographic optical element according to an embodiment of the present invention;

[0054] Figure 15 This is a flowchart illustrating a method for fabricating a color holographic optical element according to an embodiment of the present invention.

[0055] Key component symbols: 10. Fabrication system for color holographic optical elements; 11. Light source projector; 110. RGB laser; 12. Beam splitter; 120. Semi-reflective mirror; 13. Reference light modulation assembly; 130. Reflective element; 131. Color separation assembly; 1311. Blue light separation element; 1312. Green light separation element; 1313. Red light separation element; 132. Edge adjustment assembly; 1321. Red light edge adjustment element; 1322. Green light edge adjustment element; 133. Center adjustment assembly; 1331. Red light center adjustment element; 1332. Green light center adjustment element; 1333. Blue light center adjustment element; 14. Signal light modulation assembly; 140. Converging lens; 141. 4f lens system; 20. Color holographic optical element; 200. HOE substrate; 201. Transparent substrate; 202. HOE coating.

[0056] The above description of the main component symbols, together with the accompanying drawings and specific embodiments, provides a more detailed explanation of the present invention. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0059] 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 this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0060] Considering that existing color HOEs suffer from different wavelengths (λr) for recording light of different colors and different wavelengths (λp) for the corresponding reconstructed light of the same color, and that the wavelength difference (λp-λr) is also inconsistent, different degrees of focus shift occur during image reconstruction. This results in lateral focus shift (non-overlapping light spots) and axial defocus (inconsistent light spot sizes) between the RGB object lights, making it difficult to obtain high-quality image reconstruction. This application provides a color holographic optical element, its fabrication method, fabrication system, and correction method, which can solve the focus shift problem caused by wavelength inconsistency and help improve the quality of reconstructed images.

[0061] Specifically, see the attached document. Figure 3 As shown, one embodiment of the present invention provides a correction method for a color holographic optical element, which may include the following steps:

[0062] S110: Adjust the incident angle of the center rays of each color recording light according to the wavelength of the color recording light and the wavelength of the color reproducing light to correct the lateral focus shift of the color holographic optical element during image reproduction; and

[0063] S120: Adjust the incident angle of the edge rays of various color recording lights according to the wavelength of the color recording light and the wavelength of the color reproduction light, so as to correct the axial defocus of the color holographic optical element in the image reproduction process.

[0064] More specifically, the color recording light mentioned in this application can be, but is not limited to, RGB recording light, that is, the color recording light can include red recording light (R recording light), green recording light (G recording light), and blue recording light (B recording light). Correspondingly, the color reproduction light mentioned in this application can be, but is not limited to, RGB reproduction light, that is, the color reproduction light can include red reproduction light (R reproduction light), green reproduction light (G reproduction light), and blue reproduction light (B reproduction light). It is understood that in the correction method of the color holographic optical element of this application, step S110 can be performed before step S120, after step S120, or simultaneously; this application will not elaborate further on this.

[0065] It is worth noting that the recording light adjusted in this application can be implemented as an RGB reference light or an RGB signal light. Adjusting the incident angle of the reference light or signal light alone is sufficient to correct the focus shift of the color holographic optical element during image reconstruction, thereby eliminating the influence of chromatic aberration. Of course, in other examples of this application, the recording light adjusted can also be implemented as both an RGB reference light and an RGB signal light. That is, the incident angle of the reference light or signal light can be adjusted jointly to still correct the focus shift of the color holographic optical element during image reconstruction, thereby eliminating the influence of chromatic aberration. It is understood that since the reference light and signal light of the same color in the recording light are coherent (i.e., both have the same wavelength), although the wavelengths of reference light and signal light of different colors are different, the wavelengths of reference light and signal light of the same color are the same; that is, the wavelength of the R-reference light is equal to the wavelength of the R-signal light. Furthermore, the reconstruction light mentioned in this application includes the probe light incident on the color holographic optical element and the object light diffracted by the color holographic optical element.

[0066] Exemplarily, in one example of this application, such as Figure 4 As shown, step S110 of the calibration method for the color holographic optical element may include the following steps:

[0067] S111: Based on the wavelengths of the RGB reference light and the RGB probe light, the target angle of the central ray of the RGB reference light is calculated using the K-vector equation of the volume holographic grating; and

[0068] S112: Adjust the incident angle of the center ray of the RGB reference light to be equal to the target angle of the center ray of the corresponding color, so that the RGB probe light incident at the same angle is focused along the same axis by the RGB object light formed by diffraction through the color holographic optical element.

[0069] It is worth noting that before color difference correction, the incident angle θr of the center ray of the RGB reference light is equal to the incident angle θp of the center ray of the RGB probe light. The RGB probe light incident at the same angle will focus along different axes after being diffracted by existing color holographic optical elements, resulting in a lateral focus shift problem. However, in the correction method of this application, such as... Figure 5A As shown, the target angles θrc, θgc, and θbc of the center rays of the RGB reference light are calculated according to the K-vector equation K = ks - kr of the volume holographic grating. Then, the center rays of the RGB reference light are rotated to the target angles of the center rays of the corresponding colors (the incident angles of the RGB signal light remain unchanged). This process corrects the lateral focus shift during image reproduction in the fabricated color holographic optical element; in other words, as... Figure 5BAs shown, RGB probe lights incident at the same angle will be focused along the same axis by the RGB object light formed by diffraction through the color holographic optical element of this application, thus eliminating the color difference problem introduced by lateral focus shift. It is understood that the adjustment direction and magnitude of the incident angle of the center ray of the RGB reference light mentioned in this application are determined by the deviation between the reference light wavelength λr and the probe light wavelength λp. Furthermore, although in... Figure 5A In the recording optical path shown, θrc < θgc < θbc < θp, meaning all RGB reference light centers are rotated to the right. However, this is only an example and is relative to... Figure 2 The RGB detection light shown is for reference only and does not constitute a limitation on the scope of protection of this application.

[0070] It is important to emphasize that in the process of correcting the lateral focus shift problem in the HOE reconstruction process by adjusting the center ray of the reference light in the HOE recording optical path, the incident angle θp of the center ray of the probe light remains unchanged during the HOE reconstruction process.

[0071] In this example of the application, such as Figure 6 As shown, step S120 of the calibration method for the color holographic optical element may include the following steps:

[0072] S121: Based on the wavelengths of the RGB reference light and the RGB probe light, the target angles of the edge rays of the RGB reference light are calculated using the K-vector equation of the volume holographic grating; and

[0073] S122: Adjust the incident angle of the edge rays of the RGB reference light to be equal to the target angle of the edge rays of the corresponding colors, so that the RGB probe light incident at the same angle is focused in the same focal plane by the RGB object light formed by diffraction through the color holographic optical element.

[0074] It is worth noting that the correspondence between the rotation direction of the edge rays of the reference beam in the HOE recording optical path and the focal position of the object beam in the HOE reconstruction optical path is as follows: Figure 7A and Figure 7B As shown, by Figure 7A and Figure 7BIt is readily known that when the edge ray of the reference light is rotated inward, the focal point of the object light is closer to the HOE; when the edge ray of the reference light is rotated outward, the focal point of the object light is farther from the HOE. Therefore, this application calculates the target angle of the edge ray of the RGB reference light using the K-vector equation K = ks - kr of volume holographic light, and then rotates the edge ray of the RGB reference light to the target angle of the edge ray of the corresponding color (the incident angle of the RGB signal light remains unchanged). The resulting color holographic optical element corrects axial defocusing during image reconstruction; in other words, RGB probe light incident at the same angle will be focused along the same focal plane by the RGB object light formed by diffraction through the color holographic optical element of this application, thus eliminating the chromatic aberration problem introduced by axial defocusing. Thus, as... Figure 14 As shown, by adjusting the incident angle of the center ray and the incident angle of the edge ray of the reference light, this application can simultaneously correct the problems of lateral focus shift and axial defocus, so that the RGB probe light incident at the same angle will be focused along the same axis and the same focal plane by the RGB object light formed by the diffraction of the color holographic optical element of this application, so as to focus on the same point and eliminate the color difference of the color holographic optical element.

[0075] It is understood that the adjustment direction and magnitude of the incident angle of the edge rays of the RGB reference light mentioned in this application are also determined by the deviation between the reference light wavelength λr and the probe light wavelength λp. Furthermore, although in cases such as Figure 14 The corrected RGB spots in the reconstruction optical path of the color holographic optical element shown are all focused at the B spot position, but this is only an example. In other examples of this application, the corrected RGB spots in the HOE reconstruction optical path can also be focused at the R spot position, the G spot position or other positions, which will not be elaborated further in this application.

[0076] It is important to emphasize that, in the process of correcting the axial defocusing problem in the HOE reconstruction process by adjusting the edge rays of the reference light in the HOE recording optical path, the incident angle of the edge rays of the probe light remains unchanged during the HOE reconstruction process.

[0077] It is worth noting that although the correction method of the color holographic optical element in the first example of this application solves the focus shift problem by adjusting the incident angle of the reference light, in other examples of this application, the correction method of the color holographic optical element solves the focus shift problem by adjusting the incident angle of the signal light. This is because the HOE recording process and the reproduction process are reciprocal. According to the reciprocity of the reproduction color difference pattern, the signal light in the HOE recording optical path can be adjusted to achieve the color difference correction of the color holographic optical element.

[0078] Exemplarily, in one modified example of this application, such as Figure 8As shown, step S110 of the calibration method for the color holographic optical element may include the following steps:

[0079] S111': Based on the wavelengths of the RGB signal light and the RGB probe light, the target angle of the center ray of the RGB signal light is calculated using the K-vector equation of the volume holographic grating; and

[0080] S112': Adjust the incident angle of the center rays of the RGB signal light to be equal to the target angle of the center rays of the corresponding colors, so that the RGB probe light incident at the same angle is focused along the same axis by the RGB object light formed by the diffraction of the color holographic optical element.

[0081] Meanwhile, in one modified example of this application, such as Figure 9 As shown, step S120 of the calibration method for the color holographic optical element may include the following steps:

[0082] S121': Based on the wavelengths of the RGB signal light and the RGB probe light, the target angles of the edge rays of the RGB reference light are calculated using the K-vector equation of the volume holographic grating; and

[0083] S122': Adjust the incident angle of the edge rays of the RGB reference light to be equal to the target angle of the edge rays of the corresponding colors, so that the RGB probe light incident at the same angle is focused in the same focal plane by the RGB object light formed by diffraction through the color holographic optical element.

[0084] It is worth noting that, based on the same principle mentioned in the first example above, such as Figure 10 As shown, the correction method of the color holographic optical element in the second example of this application can correct the lateral focus shift by adjusting the incident angle of the center ray of the signal light and correct the axial chromatic aberration by adjusting the incident angle of the edge ray of the signal light, which will not be elaborated further in this application.

[0085] It is worth mentioning that, according to another aspect of this application, such as Figure 11 and Figure 12As shown, one embodiment of this application provides a fabrication system 10 for a color holographic optical element, used to coherently record color signal light and color reference light at a HOE substrate 200 to form a color holographic optical element 20. The fabrication system 10 may include a light source projector 11 for projecting color recording light, a beam splitter 12 disposed in the projection optical path of the light source projector 11, a reference light modulation assembly 13 disposed in the reference light optical path of the beam splitter 12, and a signal light modulation assembly 14 disposed in the signal light optical path of the beam splitter 12. The beam splitter 12 is used to split the color recording light from the light source projector 11 into a color reference light propagating along the reference light optical path and a color signal light propagating along the signal light optical path. The reference light modulation assembly 13 is used to modulate the color reference light from the beam splitter 12, so that the modulated color reference light is incident rearward onto the HOE substrate 200. The signal light modulation component 14 is used to modulate the colored signal light from the beam splitter 12 so that the modulated colored signal light is incident forward onto the HOE substrate 200.

[0086] Specifically, the reference light modulation component 13 or the signal light modulation component 14 is used to adjust the incident angles of the center rays and edge rays of various colors in the color reference light or the color signal light, respectively, so that they are equal to the target angles of the center rays and edge rays of the corresponding colors. This corrects the focus shift of the color holographic optical element 20 during image reproduction, thereby eliminating the chromatic aberration of the color holographic optical element 20. In this way, the modulated color reference light and the modulated color signal light interfere and record on the HOE substrate 200, so that the HOE substrate 200 forms the color holographic optical element 20.

[0087] Optionally, such as Figure 12 As shown, the light source projector 11 can be implemented as an RGB laser 110, for projecting RGB three-color laser light as RGB recording light.

[0088] Optionally, such as Figure 12 As shown, the beam splitter 12 can be, but is not limited to, implemented as a semi-reflective mirror 120, used to reflect 50% of the RGB recording light to form one RGB reference light and transmit 50% of the RGB recording light to form one RGB signal light.

[0089] It is worth noting that the fabrication system 10 for the color holographic optical element of this application can adjust the incident angle of the center ray and the incident angle of the edge ray of the color reference light separately to achieve focus shift correction, and can also adjust the incident angle of the center ray and the incident angle of the edge ray of the color signal light separately to achieve focus shift correction, or can also adjust the incident angles of the color reference light and the color signal light in a coordinated manner to achieve focus shift correction.

[0090] Exemplarily, in the first example of this application, such as Figure 12 As shown, the reference light modulation component 13 is located on the reflective side of the beam splitter 12. It is used to adjust the incident angle of the center rays of various color reference lights according to the wavelengths of the RGB reference light and the RGB reproduced light, respectively, to correct the lateral focus shift of the color holographic optical element 20 during image reproduction. It also adjusts the incident angle of the edge rays of various color reference lights, respectively, to correct the axial defocus of the color holographic optical element 20 during image reproduction. Simultaneously, the signal light modulation component 14 can be, but is not limited to, implemented as a converging lens 140 located on the transmission side of the beam splitter 12, to converge the RGB signal light from the beam splitter 12, so that the RGB signal light is imaged in front of the HOE substrate 200.

[0091] Optionally, such as Figure 12 As shown, the reference light modulation component 13 may include a color separation component 131, an edge adjustment component 132, and a center adjustment component 133 respectively disposed in the reference light optical path. The color separation component 131 is used to split the RGB reference light into R reference light, G reference light, and B reference light. The edge adjustment component 132 is used to adjust the incident angle of the edge rays of the R reference light, the G reference light, and the B reference light respectively to be equal to the target angle of the edge rays of the corresponding colors; the center adjustment component 133 is used to adjust the incident angle of the center rays of the R reference light, the G reference light, and the B reference light respectively to be equal to the target angle of the center rays of the corresponding colors; wherein the target angle of the edge rays and the target angle of the center rays are calculated respectively based on the wavelength of the RGB reference light and the wavelength of the RGB probe light through the K-vector equation of the volume holographic grating. In this way, the R reference light, the G reference light, and the B reference light will be incident on the HOE substrate 200 at the edge ray target angle and the center ray target angle of the corresponding color, and interfere with the RGB signal light incident on the HOE substrate 200 to produce an achromatic color holographic optical element 20.

[0092] Optionally, such as Figure 12As shown, the color separation component 131, the edge adjustment component 132, and the center adjustment component 133 are sequentially arranged in the reference light path of the beam splitter 12, such that the RGB reference light first passes through the edge adjustment component 132 to adjust the incident angle of the edge light rays, and then passes through the center adjustment component 133 to adjust the incident angle of the center light rays. It is understood that in other examples of this application, the color separation component 131, the center adjustment component 133, and the edge adjustment component 132 can be sequentially arranged in the reference light path of the beam splitter 12, such that the RGB reference light first passes through the center adjustment component 133 to adjust the incident angle of the center light rays, and then passes through the edge adjustment component 132 to adjust the incident angle of the edge light rays. This application will not elaborate further on this aspect.

[0093] Optionally, such as Figure 12 As shown, the color separation component 131 may include a blue light separation element 1311 for reflecting blue light and transmitting red and green light, a green light separation element 1312 for reflecting green light and transmitting red light, and a red light separation element 1313 for reflecting red light. The blue light separation element 1311, the green light separation element 1312, and the red light separation element 1313 are arranged sequentially in the reference light path of the color separation element 12. Thus, firstly, the B reference light from the RGB reference light from the beam splitter 12 is reflected by the blue light splitter 1311 to propagate to the edge adjustment assembly 132; simultaneously, the RG reference light from the RGB reference light from the beam splitter 12 passes through the blue light splitter 1311 to propagate to the green light splitter 1312; then, the G reference light from the RG reference light is reflected by the green light splitter 1312 to propagate to the edge adjustment assembly 132; simultaneously, the R reference light from the RG reference light passes through the green light splitter 1312 to propagate to the red light splitter 1313; finally, the R reference light is reflected by the red light splitter 1313 to propagate to the edge adjustment assembly 132.

[0094] It is worth noting that in the above examples of this application, the blue light-reflecting element 1311, the green light-reflecting element 1312, and the red light-reflecting element 1313 can be implemented as different selectively permeable films to reflect blue light, green light, and red light respectively. Of course, in other examples of this application, the arrangement order of the blue light-reflecting element 1311, the green light-reflecting element 1312, and the red light-reflecting element 1313 can be interchanged, as long as a suitable selectively permeable film is used, which will not be elaborated further in this application.

[0095] Optionally, such as Figure 12As shown, the edge adjustment assembly 132 may include a red light edge adjustment element 1321 located on the reflective side of the red light element 1313 and a green light edge adjustment element 1322 located on the reflective side of the green light element 1312. The red light edge adjustment element 1321 is used to modulate the R reference light from the red light element 1313 so that the incident angle of the edge ray of the R reference light is adjusted to the target angle of the edge ray of the corresponding color and then propagates to the center adjustment assembly 133. The green light edge adjustment element 1322 is used to modulate the G reference light from the green light element 1312 so that the incident angle of the edge ray of the G reference light is adjusted to the target angle of the edge ray of the corresponding color and then propagates to the center adjustment assembly 133.

[0096] It is worth noting that in the above example of this application, the incident angle of the edge rays of the B reference light from the blue light-dispersing element 1311 is not adjusted, so that the modulated R reference light and G reference light are corrected based on the B reference light. In another example of this application, the edge adjustment component 132 may further include a blue light edge adjustment element (not shown in the figure) located on the reflective side of the blue light-dispersing element 1311, for adjusting the incident angle of the edge rays of the B reference light from the blue light-dispersing element 1311 to the target angle of the edge rays of the corresponding color before propagating to the center adjustment component 133. It is understood that in other examples of this application, the edge adjustment component 132 may also not include the red light-dispersing element 1313 or the green light-dispersing element 1312, and be corrected based on the R reference light or the G reference light, which will not be elaborated further in this application.

[0097] Optionally, the red light edge adjustment element 1321 and the green light edge adjustment element 132 in the edge adjustment assembly 132 may, but are not limited to, be implemented as positive lenses or negative lenses.

[0098] Optionally, such as Figure 12 As shown, the center adjustment component 133 may include a red light center adjustment element 1331, a green light center adjustment element 1332, and a blue light center adjustment element 1333. The red light center adjustment element 1331 is used to modulate the R reference light from the red light edge adjustment element 1321, so that the incident angle of the center ray of the R reference light is adjusted to the target angle of the center ray of the corresponding color before it is incident on the HOE substrate 200. The green light center adjustment element 1332 is used to modulate the G reference light from the green light edge adjustment element 1322, so that the incident angle of the center ray of the G reference light is adjusted to the target angle of the center ray of the corresponding color before it is incident on the HOE substrate 200. The blue light center adjustment element 1333 is used to modulate the B reference light from the blue light element 1311, so that the incident angle of the center ray of the B reference light is adjusted to the target angle of the center ray of the corresponding color before it is incident on the HOE substrate 200.

[0099] Optionally, the red light center adjustment element 1331, the green light center adjustment element 1332, and the blue light center adjustment element 1333 can be, but are not limited to, implemented as plane mirrors. It is understood that this application can adjust the incident angle of the center light rays of the corresponding colors by adjusting the tilt angle of each plane mirror, and this will not be elaborated further.

[0100] It is worth noting that in the second example of this application, such as Figure 13 As shown, the reference light modulation component 13 can be, but is not limited to, a reflective element 130 located on the reflective side of the beam splitter 12, used to reflect the RGB reference light from the beam splitter 12 to be incident on the front surface of the HOE substrate 200. Simultaneously, the signal light modulation component 14 is located on the transmission side of the beam splitter 12, used to adjust the incident angle of the center rays of various color signal lights according to the wavelengths of the RGB reference light and the RGB reproduced light, respectively, to correct the lateral focus shift of the color holographic optical element 20 during image reproduction, and to adjust the incident angle of the edge rays of various color signal lights, respectively, to correct the axial defocus of the color holographic optical element 20 during image reproduction. It is understood that the reflective element 130 of this application can be, but is not limited to, a planar reflector.

[0101] Similarly, such as Figure 13 As shown, the signal light modulation assembly 14 may include the aforementioned color separation assembly 131, edge adjustment assembly 132, center adjustment assembly 133, and 4f lens system 141 arranged sequentially in the signal light path. The color separation assembly 131 is used to split the RGB signal light into R signal light, G signal light, and B signal light. The edge adjustment assembly 132 is used to adjust the incident angles of the edge rays of the R, G, and B signal lights to be equal to the target angles of the edge rays of the corresponding colors. The center adjustment assembly 133 is used to adjust the incident angles of the center rays of the R, G, and B signal lights to be equal to the target angles of the center rays of the corresponding colors. The target angles of the edge rays and the target angles of the center rays are calculated based on the wavelengths of the RGB signal light and the RGB probe light, respectively, using the K-vector equation of the volume holographic grating. The 4f lens system 141 is used to modulate the RGB signal light adjusted by the center adjustment assembly 133, so that the adjusted RGB signal light is imaged in front of the HOE substrate 200. Understandably, in this example, the signal light modulation component 14 may further include a converging lens 140 located between the 4f lens system 141 and the HOE substrate 200, for converging the RGB signal light from the 4f lens system 141 so that the RGB signal light is imaged in front of the HOE substrate 200.

[0102] It is worth noting that in the second example described above in this application, the structures of the color separation component 131, the edge adjustment component 132, and the center adjustment component 133 can be the same as those in the first example described above, in order to achieve the same color separation and adjustment functions. This application will not elaborate further on this. It is understood that after the recording optical path in the fabrication system of this color holographic optical element is calibrated and stabilized, it can be used for mass production of achromatic color HOEs, which is highly efficient and low-cost, facilitating promotion and application.

[0103] Optionally, such as Figure 12 and Figure 13 As shown, the HOE substrate 200 of this application may include a light-transmitting substrate 201 and an HOE coating 202 disposed on the light-transmitting substrate 201. The HOE coating 202 of the HOE substrate 200 faces the reference light modulation component 13, so that the reference light modulated by the reference light modulation component 13 is directly incident on the HOE coating 202. The HOE coating 202 of the HOE substrate 200 faces away from the signal light modulation component 14, so that the signal light modulated by the signal light modulation component 14 first passes through the light-transmitting substrate 201 and then is incident on the HOE coating 202. In this way, the modulated reference light faces the HOE coating 202 of the HOE substrate 200, and the modulated signal light faces away from the HOE coating 202 of the HOE substrate 200, thereby interfering at the HOE coating 202 and being recorded by the HOE coating 202 to form the color holographic optical element 20.

[0104] It is worth mentioning that, attached Figure 14 A color holographic optical element 20 according to an embodiment of this application is shown, which can be fabricated by the color holographic optical element fabrication system 10 described above.

[0105] For example, such as Figure 14 As shown, the color holographic optical element 20 of this application includes a light-transmitting substrate 201 and a HOE coating 202 disposed on the light-transmitting substrate 201. The HOE coating 202 records information on the interference between the modulated color reference light and the modulated color signal light. The incident angles of the center rays and the incident angles of the edge rays of various colors in the modulated color reference light or the modulated color signal light are adjusted to the target angles of the center rays and the target angles of the edge rays of the corresponding colors, so as to eliminate the color difference introduced by the focus shift of the color holographic optical element 20.

[0106] It is worth noting that the material of the HOE coating 202 can be, but is not limited to, a polymer; and the material of the light-transmitting substrate 201 can be, but is not limited to, transparent glass. Furthermore, the color holographic optical element 20 of this application can be applied to solutions based on LBS+HOE near-eye display optical path architectures, which helps to achieve near-eye displays of colorless, high-quality color virtual information.

[0107] It is worth mentioning that, attached Figure 15 A method for fabricating a color holographic optical element according to an embodiment of this application is shown, which may include the following steps:

[0108] S210: Based on the wavelength of the color recording light and the wavelength of the color reproduction light, the center ray target angle and edge ray target angle of the reference light or signal light of various colors in the color recording light are calculated respectively through the K vector equation of the volume holographic grating.

[0109] S220: Modulate the colored reference light and the colored signal light to be incident on the HOE substrate, wherein the incident angle of the center ray and the incident angle of the edge ray of the modulated colored reference light or colored signal light are equal to the target angle of the center ray and the target angle of the edge ray of the corresponding color, respectively; and

[0110] S230: The information of the interference between the colored reference light and the colored signal light is recorded through the HOE substrate to form a colored holographic optical element.

[0111] It is worth noting that steps S220 and S230 in the manufacturing method for holographic optical elements of this application are performed in parallel without any order between them.

[0112] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A system for fabricating color holographic optical elements, characterized in that, include: A light source projector used to project colored recording light; A beam splitter is disposed in the projection optical path of the light source projector to split the color recording light from the light source projector into a color reference light propagating along the reference light optical path and a color signal light propagating along the signal light optical path. A reference light modulation assembly is disposed in the reference light path of the beam splitter and is used to modulate the color reference light from the beam splitter so that the modulated color reference light is incident backward onto the HOE substrate. as well as A signal light modulation component is disposed in the signal light path of the beam splitter and is used to modulate the color signal light from the beam splitter so that the modulated color signal light is incident forward onto the HOE substrate. The reference light modulation component or the signal light modulation component is used to adjust the incident angle of the center ray and the incident angle of the edge ray of each color light in the color reference light or the color signal light so as to be equal to the target angle of the center ray and the target angle of the edge ray of the corresponding color, so that the modulated color reference light and the modulated color signal light interfere and record on the HOE substrate to form a color holographic optical element. The reference light modulation component is located on the reflective side of the beam splitter and is used to adjust the incident angle of the center rays of various color reference lights according to the wavelength of the RGB reference light and the wavelength of the RGB reproduced light, so as to correct the lateral focus shift of the color holographic optical element during the image reproduction process; and to adjust the incident angle of the edge rays of various color reference lights, so as to correct the axial defocus of the color holographic optical element during the image reproduction process; the signal light modulation component is a converging lens located on the transmission side of the beam splitter and is used to converge the RGB signal light from the beam splitter so that the RGB signal light is imaged in front of the HOE substrate; The reference light modulation component includes a color separation component, an edge adjustment component, and a center adjustment component arranged sequentially in the reference light optical path; the color separation component is used to split the RGB reference light into R reference light, G reference light, and B reference light; the edge adjustment component is used to adjust the incident angle of the edge rays of the R reference light, the G reference light, and the B reference light to be equal to the target angle of the edge rays of the corresponding colors; the center adjustment component is used to adjust the incident angle of the center rays of the R reference light, the G reference light, and the B reference light to be equal to the target angle of the center rays of the corresponding colors. Specifically, based on the wavelengths of the RGB reference light and the RGB probe light, the target angle of the center ray of the RGB reference light or the RGB signal light is calculated using the K-vector equation of the volume holographic grating.

2. The fabrication system for a color holographic optical element according to claim 1, characterized in that, The color separation component includes a blue light separating element for reflecting blue light and transmitting red and green light, a green light separating element for reflecting green light and transmitting red light, and a red light separating element for reflecting red light. The blue light separating element, the green light separating element, and the red light separating element are selectively permeable films arranged sequentially in the reference light path.

3. The fabrication system for a color holographic optical element according to claim 2, characterized in that, The edge adjustment assembly includes a red light edge adjustment element located on the reflective side of the red light element and a green light edge adjustment element located on the reflective side of the green light element. The red light edge adjustment element is used to modulate the R reference light from the red light element so that the incident angle of the edge ray of the R reference light is adjusted to the target angle of the edge ray of the corresponding color and then propagates to the center adjustment assembly. The green light edge adjustment element is used to modulate the G reference light from the green light element so that the incident angle of the edge ray of the G reference light is adjusted to the target angle of the edge ray of the corresponding color and then propagates to the center adjustment assembly.

4. The fabrication system for a color holographic optical element according to claim 3, characterized in that, The red light edge adjustment element and the green light edge adjustment element are positive lenses or negative lenses.

5. The fabrication system for a color holographic optical element according to claim 4, characterized in that, The center adjustment assembly includes a red light center adjustment element, a green light center adjustment element, and a blue light center adjustment element. The red light center adjustment element is used to modulate the R reference light from the red light edge adjustment element so that the incident angle of the center ray of the R reference light is adjusted to the target angle of the center ray of the corresponding color before it is incident on the HOE substrate. The green light center adjustment element is used to modulate the G reference light from the green light edge adjustment element so that the incident angle of the center ray of the G reference light is adjusted to the target angle of the center ray of the corresponding color before it is incident on the HOE substrate. The blue light center adjustment element is used to modulate the B reference light from the blue light element so that the incident angle of the center ray of the B reference light is adjusted to the target angle of the center ray of the corresponding color before it is incident on the HOE substrate.

6. The fabrication system for a color holographic optical element according to claim 5, characterized in that, The red light center adjustment element, the green light center adjustment element, and the blue light center adjustment element are planar reflectors.

7. A system for fabricating color holographic optical elements, characterized in that, include: A light source projector used to project colored recording light; A beam splitter is disposed in the projection optical path of the light source projector to split the color recording light from the light source projector into a color reference light propagating along the reference light optical path and a color signal light propagating along the signal light optical path. A reference light modulation assembly is disposed in the reference light path of the beam splitter and is used to modulate the color reference light from the beam splitter so that the modulated color reference light is incident backward onto the HOE substrate. as well as A signal light modulation component is disposed in the signal light path of the beam splitter and is used to modulate the color signal light from the beam splitter so that the modulated color signal light is incident forward onto the HOE substrate. The reference light modulation component or the signal light modulation component is used to adjust the incident angle of the center ray and the incident angle of the edge ray of each color light in the color reference light or the color signal light so as to be equal to the target angle of the center ray and the target angle of the edge ray of the corresponding color, so that the modulated color reference light and the modulated color signal light interfere and record on the HOE substrate to form a color holographic optical element. The reference light modulation component is a reflective element located on the reflective side of the beam splitter, used to reflect the RGB reference light from the beam splitter so that the RGB reference light is incident on the front surface of the HOE substrate; the signal light modulation component is located on the transmissive side of the beam splitter, used to adjust the incident angle of the center rays of various color signal lights according to the wavelength of the RGB signal light and the wavelength of the RGB reproduced light, so as to correct the lateral focus shift of the color holographic optical element in the image reproduction process; and to adjust the incident angle of the edge rays of various color signal lights, so as to correct the axial defocus of the color holographic optical element in the image reproduction process; The signal light modulation component includes a color separation component, an edge adjustment component, a center adjustment component, and a 4f lens system arranged sequentially in the signal light path. The color separation component is used to split the RGB signal light into R signal light, G signal light, and B signal light. The edge adjustment component is used to adjust the incident angle of the edge rays of the R signal light, G signal light, and B signal light to be equal to the target angle of the edge rays of the corresponding colors. The center adjustment component is used to adjust the incident angle of the center rays of the R signal light, G signal light, and B signal light to be equal to the target angle of the center rays of the corresponding colors. The 4f lens system is used to modulate the RGB signal light adjusted by the center adjustment component so that the adjusted RGB signal light is imaged in front of the HOE substrate. Specifically, based on the wavelengths of the RGB reference light and the RGB probe light, the target angle of the center ray of the RGB reference light or the RGB signal light is calculated using the K-vector equation of the volume holographic grating.

8. A method for fabricating a color holographic optical element, characterized in that, A fabrication system for a color holographic optical element as described in any one of claims 1 to 7, comprising the steps of: Based on the wavelength of the color recording light and the wavelength of the color reproduction light, the center ray target angle and the edge ray target angle of the reference light or signal light of various colors in the color recording light are calculated respectively using the K-vector equation of the volume holographic grating. A modulated color reference light and a color signal light are incident on a HOE substrate, wherein the incident angle of the center ray and the incident angle of the edge ray of the modulated color reference light or color signal light are equal to the target angle of the center ray and the target angle of the edge ray of the corresponding color, respectively; and The HOE substrate is used to record the interference information of the colored reference light and the colored signal light to form a colored holographic optical element.

9. A method for correcting a color holographic optical element, characterized in that, A fabrication system for a color holographic optical element as described in any one of claims 1 to 7, comprising the steps of: Based on the wavelengths of the color recording light and the color reproduction light, the incident angles of the central rays of each color recording light are adjusted to correct the lateral focus shift of the color holographic optical element during the image reproduction process. and Based on the wavelengths of the color recording light and the color reproduction light, the incident angles of the edge rays of various color recording lights are adjusted to correct the axial defocusing of the color holographic optical element during the image reproduction process.

10. The calibration method for a color holographic optical element according to claim 9, characterized in that, The step of adjusting the incident angle of the center rays of various color recording lights according to the wavelengths of the color recording light and the color reproduction light to correct the lateral focus shift of the color holographic optical element during image reproduction includes the following steps: Based on the wavelengths of the RGB reference light and the RGB probe light, the target angle of the center ray of the RGB reference light or the RGB signal light is calculated using the K-vector equation of the volume holographic grating; and Adjust the incident angle of the center rays of the RGB reference light or RGB signal light to be equal to the target angle of the center rays of the corresponding colors, so that the RGB probe light incident at the same angle is focused along the same axis after being diffracted by the color holographic optical element to form the RGB object light.

11. The calibration method for a color holographic optical element according to claim 10, characterized in that, The step of adjusting the incident angle of the edge rays of various color recording lights according to the wavelength of the color recording light and the wavelength of the color reproducing light to correct the axial defocus of the color holographic optical element during the image reproduction process includes the following steps: Based on the wavelengths of the RGB reference light and the RGB probe light, the target angles of the edge rays of the RGB reference light or the RGB signal light are calculated using the K-vector equation of the volume holographic grating; and Adjust the incident angle of the edge rays of the RGB reference light or RGB signal light to be equal to the target angle of the edge rays of the corresponding colors, so that the RGB probe light incident at the same angle is focused in the same focal plane by the RGB object light formed by the diffraction of the color holographic optical element.

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