Holographic optical thin film, preparation method, preparation system and display system applying holographic optical thin film

Abstract

The invention provides a holographic optical film, a preparation method, a preparation system and a display system applying the holographic optical film, and the preparation system comprises a laser used for generating a laser beam; the beam splitting module is arranged on a propagation path of the laser beam and is used for splitting the laser beam to generate a reference beam and a signal beam; the reference light module is arranged on a propagation path of the reference light beam and is used for reflecting the reference light beam to one side of the holographic photosensitive film material; the scattering film is positioned on the other side of the holographic photosensitive film material; the signal light module is arranged on a propagation path of the signal light beam and is used for reflecting the signal light beam to the scattering film; wherein the signal light beam penetrates through the scattering film and then irradiates the holographic photosensitive film material together with the reference light beam, interference exposure is carried out on the holographic photosensitive film material, and a holographic optical film is formed. The HUD has excellent display performance and optical perspective effect, and the display effect of the HUD can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of directional scattering imaging, and in particular to a holographic optical film, a preparation method, a preparation system and a display system using the same. Background Art

[0002] Head-up-Display (HUD) technology is widely used in the automotive field to provide drivers with key information without taking their eyes off the road.

[0003] However, the traditional HUD generates a virtual image by reflecting light from the windshield. According to the principle of geometric optics, the sum of the transmittance and reflectance of the material is less than 100%. This means that if the windshield is to maintain good transparency (high transmittance), its reflectivity will be reduced accordingly, resulting in insufficient brightness of the displayed information. In the prior art, in order to compensate for this, it is usually necessary to increase the brightness of the projection light source, thereby increasing the power consumption of the system. Therefore, there is room for improvement. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a holographic optical film, a preparation method, a preparation system and a display system using the same, so as to solve the technical problems of insufficient display information brightness and high power consumption of the head-up display system in the prior art.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a holographic optical film, wherein the holographic optical film is prepared by interfering a reference beam and a signal beam on a holographic photosensitive film material, and the scattering angle on the holographic optical film is in a gradual relationship;

[0006] The reference beam and the signal beam are formed by splitting a laser beam, the reference beam is irradiated on one side of the holographic photosensitive film material, and the signal beam is irradiated on the other side of the holographic photosensitive film material after passing through a scattering film.

[0007] The present invention also provides a method for preparing a holographic optical film, comprising:

[0008] Generate a laser beam, and split the laser beam to generate a reference beam and a signal beam;

[0009] Reflecting the reference beam to one side of the holographic photosensitive film material;

[0010] Laminating a scattering film to the other side of the holographic photosensitive film material, and reflecting the signal light beam onto the scattering film;

[0011] The signal light beam passes through the scattering film and is irradiated onto the holographic photosensitive film material simultaneously with the reference light beam, so as to perform interference exposure on the holographic photosensitive film material and form a holographic optical film.

[0012] The present invention also provides a system for preparing a holographic optical film, comprising:

[0013] A laser for generating a laser beam;

[0014] A beam splitting module, disposed on the propagation path of the laser beam, for splitting the laser beam to generate a reference beam and a signal beam;

[0015] A reference light module, disposed on the propagation path of the reference light beam, and used for reflecting the reference light beam to one side of the holographic photosensitive film material;

[0016] A scattering film, located on the other side of the holographic photosensitive film material;

[0017] A signal light module, disposed on the propagation path of the signal light beam, and used for reflecting the signal light beam onto the scattering film;

[0018] Wherein, after passing through the scattering film, the signal light beam is irradiated onto the holographic photosensitive film material simultaneously with the reference light beam, so as to perform interference exposure on the holographic photosensitive film material to form a holographic optical film.

[0019] In one embodiment of the present invention, the beam splitting module comprises:

[0020] A first half-wave plate, located on the propagation path of the laser beam, and used to adjust the polarization direction of the laser beam; and

[0021] The polarization beam splitter is located on the propagation path of the laser beam and is used to perform beam splitting processing on the adjusted laser beam to generate the reference beam and the signal beam.

[0022] In one embodiment of the present invention, the reference light module includes:

[0023] A second half-wave plate, located on the propagation path of the reference beam, and adjusting the polarization direction of the reference beam;

[0024] A first beam expander, used for performing beam expansion processing on the adjusted reference beam;

[0025] A first collimating lens, used for collimating the reference beam after beam expansion;

[0026] a first reflecting mirror, used for reflecting the reference beam after the collimation process, wherein a propagation path of the reflected reference beam is perpendicular to the holographic photosensitive film material; and

[0027] The first lens is used to diverge the reflected reference light beam and irradiate it onto the holographic photosensitive film material.

[0028] In one embodiment of the present invention, the signal optical module includes:

[0029] A third half-wave plate, located on the propagation path of the signal light beam, and adjusting the polarization direction of the signal light beam;

[0030] A second beam expander, used for performing beam expansion processing on the adjusted signal light beam;

[0031] A second collimating lens, used for collimating the signal light beam after beam expansion;

[0032] A second reflector, used for reflecting the collimated signal light beam; and

[0033] The second lens is used to focus the reflected signal light beam and irradiate it onto the scattering film.

[0034] In one embodiment of the present invention, the scattering film is attached to the other side of the holographic photosensitive film material, and the scattering angle of each point on the scattering film is related to its position.

[0035] In one embodiment of the present invention, the scattering angle θ of each point on the scattering film is i (xi) satisfies the following formula:

[0036]

[0037] Wherein, xi represents the distance between a certain point on the scattering film and the origin, L represents the distance between the origin and the focal plane of the second lens, and D represents the scattering range of the certain point on the focal plane of the second lens.

[0038] In one embodiment of the present invention, the scattering film is parallel to the second lens, and the scattering angle of each point on the scattering film is the same.

[0039] The present invention also provides a display system, comprising:

[0040] A projection imager for generating real image light;

[0041] an optical combiner, used for performing directional scattering imaging on the real image light,

[0042] Wherein, the optical combiner is the holographic optical film according to claim 1, or the holographic optical film prepared by the method of claim 2, or the holographic optical film prepared by any system of claims 3-9.

[0043] As described above, the holographic optical film, preparation method, preparation system and display system of the present invention have the following beneficial effects: the holographic optical film of the present invention has the characteristics of simple and light structure and low cost, and at the same time exhibits excellent display performance and optical perspective effect, which greatly promotes the wide application and development of HUD technology in multiple fields such as vehicle-mounted / aircraft-mounted equipment, entertainment display and exhibition. The directional scattering holographic film imaging technology adopted by the present invention theoretically achieves 100% transmittance and 100% diffraction efficiency. In addition, since the image is directly projected onto the windshield, the entire optical path design is more concise and compact, further reducing the physical size of the system and providing convenient conditions for integrated installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Shown is a structural schematic diagram of a head-up display system provided by an embodiment of the present invention.

[0045] Figure 2 Shown is a schematic diagram of the arrangement positions of a projection imager and an optical combiner in one embodiment of the present invention.

[0046] Figure 3 Shown is a schematic structural diagram of a system for preparing a holographic optical film provided by an embodiment of the present invention.

[0047] Figure 4 It is a schematic diagram showing the arrangement positions of the second lens and the scattering film in one embodiment of the present invention.

[0048] Figure 5 Shown is a schematic diagram of the scattering angle of a wide bandwidth light source according to an embodiment of the present invention.

[0049] Figure 6 Shown is a schematic diagram of a display of a wide bandwidth light source according to an embodiment of the present invention.

[0050] Figure 7 FIG. 4 is a schematic diagram showing another arrangement position of the second lens and the scattering film in an embodiment of the present invention.

[0051] Figure 8 Shown is a structural schematic diagram of yet another head-up display system provided by an embodiment of the present invention.

[0052] Fig. 9 A schematic diagram showing the steps of a method for preparing a holographic optical film provided by an embodiment of the present invention is shown.

[0053] In the figure:

[0054] 100, head-up display system; 110, projection imager; 120, optical combiner; 130, automobile windshield; 140, eye box; 150, human eye;

[0055] 200, preparation system; 210, laser; 220, beam splitter module; 221, first half-wave plate; 222, polarization beam splitter; 230, reference light module; 231, second half-wave plate; 232, first beam expander; 233, first collimating lens; 234, first reflector; 235, first lens; 240, scattering film; 250, signal light module; 251, third half-wave plate; 252, second beam expander; 253, second collimating lens; 254, second reflector; 255, second lens; 260, holographic photosensitive film material;

[0056] 300, laser beam; 301, reference beam; 302, signal beam. DETAILED DESCRIPTION

[0057] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0058] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0059] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0060] The present invention provides a holographic optical film, a preparation method, a preparation system and a display system using the same, which relate to the field of directional scattering imaging technology, and can be specifically applied to solve the technical problems of insufficient display information brightness and high power consumption of the head-up display system in the prior art. The present invention adopts directional scattering holographic film imaging technology, theoretically achieving 100% transmittance and 100% diffraction efficiency, and applies directional scattering holographic film in the head-up display system to realize direct projection of the image onto the windshield, making the entire optical path design more concise and compact, further reducing the physical size of the system, and providing convenient conditions for integrated installation. The following is a detailed description through specific embodiments.

[0061] See also Figure 1 The present invention provides a head-up display system 100, which may include a projection imager 110 and an optical combiner 120. The projection imager 110 may be disposed on the inner side of the front windshield 130 of the automobile, and may be used to generate real image light. The optical combiner 120 is a holographic optical film with directional scattering capability, which may be attached to the inner side of the front windshield 130 of the automobile. The optical combiner 120 may perform directional scattering imaging on the light of a specific wavelength in the projection imager 110, and its imaging process is equivalent to the superposition of a convex lens and a scattering film. In this embodiment, the holographic optical film may enable the image to be efficiently imaged on the film, thereby ensuring that the head-up display system 100 has good transmittance, and only the large eye box visible to the driver is imaged. The real image light emitted by the projection imager 110 is scattered at a certain angle by the optical combiner 120. The main light emitted from each point on the optical combiner 120 converges to the center point O of the eye box 140, and the scattered light formed by the divergence of each point overlaps at the eye box 140. It can be seen that the optical combiner 120 can image the image directly on the windshield, making the overall optical path simple and small in size. At the same time, the optical combiner 120 also allows external light from the real scene to be transmitted, so that the image outside the car can be efficiently projected into the driver's viewing range. Different from traditional geometric optics, the present invention uses holographic film imaging with directional scattering ability, which theoretically has 100% transmittance and 100% diffraction efficiency. Therefore, the head-up display system of the present invention has the technical advantages of simple structure, light weight, and low preparation cost, and the present invention still has good optical perspective effect while ensuring good display performance.

[0062] See also Figure 1 , Figure 2 In one embodiment of the present invention, the main light emitted from each point on the optical combiner 120 converges to the center point O of the eye box 140. Therefore, the scattering angle of each point on the optical combiner 120 is related to the position of the point. Figure 2As shown, the windshield 130 has an inclination angle of β, and the optical combiner 120 is attached to the inner side of the windshield 130, that is, the optical combiner 120 is placed in front of the human eye 150 at an angle of β. In this embodiment, the length of the optical combiner 120 is set to X, the distance between its upper left vertex A and the surface where the eye box 140 is located is set to L, and the lower right vertex A is set to ′ The distance between the optical combiner 120 and the surface where the eye box 140 is located is set to F. If the upper left vertex A of the optical combiner 120 is its origin, then a point A on it xi The distance R(xi) to the surface where the eye box 140 is located can satisfy the following formula:

[0063] R(xi)=xi·cosβ+L;

[0064] Where xi represents A xi represents the distance from the origin to the surface where the eye box 140 is located, β represents the tilt angle of the optical combiner 120, and L represents the distance from the origin to the surface where the eye box 140 is located.

[0065] In this embodiment, it is known that the size of the eye box 140 is D. According to the arc center angle formula, point A xi The scattering angle θ i (xi) can satisfy the following formula:

[0066]

[0067] It can be seen from the above formula that the scattering angles of various points on the optical combiner 120 are in a gradual relationship.

[0068] See also Figure 3The present invention also provides a system for preparing a holographic optical film, which can be used to prepare the above-mentioned holographic optical film with directional scattering ability. In this embodiment, the preparation system 200 may include a laser 210, a beam splitting module 220, a reference light module 230, a scattering film 240 and a signal light module 250. Among them, the laser 210 can be used to generate a laser beam 300 with a specific wavelength and high coherence. In this embodiment, the laser 210 can use a helium-neon (He-Ne) laser, an argon ion laser or a solid-state laser. The beam splitting module 220 can be arranged on the propagation path of the laser beam 300, which can be used to split the laser beam 300 to generate a reference beam 301 and a signal beam 302. The reference light module 230 can be arranged on the propagation path of the reference beam 301, which can be used to reflect the reference beam 301 to one side of the holographic photosensitive film material 260. The scattering film 240 can be located on the other side of the holographic photosensitive film material 260. The signal light module 250 can be arranged on the propagation path of the signal light beam 302, and can be used to reflect the signal light beam 302 onto the scattering film 240. The holographic photosensitive film material 260 can be arranged on the transparent substrate of the holographic optical element, and its surface can record the directional scattering information generated by sequential exposure or parallel exposure. The directional scattering information is synchronously irradiated on the same position of the holographic photosensitive film material 260 by two coherent point light sources from both sides of the holographic photosensitive film material 260, i.e., the front and back sides of the holographic photosensitive film material 260, and interference is generated. The above imaging process is equivalent to the superposition of a convex lens and a scattering film with a non-fixed scattering angle, and can be used to perform directional scattering imaging on the light in a specific wavelength range emitted by the projection imager 110. In this embodiment, the reference beam 301 is irradiated on one side of the holographic photosensitive film material 260, and the signal beam 302 is irradiated on the other side of the holographic photosensitive film material 260 after passing through the scattering film 240. The reference beam 301 and the signal beam 302 are coherent point light sources, which can form interference fringes on the holographic photosensitive film material 260, thereby realizing interference exposure of the holographic photosensitive film material 260 and forming the required holographic optical film with directional scattering capability.

[0069] See also Figure 3In one embodiment of the present invention, the beam splitter module 220 may include a first half-wave plate 221 and a polarization beam splitter 222. The first half-wave plate 221 is perpendicular to the propagation path of the laser beam 300. The first half-wave plate 221 can be used to adjust the polarization direction of the laser beam 300. The polarization beam splitter 222 can be used to receive the adjusted laser beam 300 and split it into two beams with mutually perpendicular polarization directions, namely a reference beam 301 and a signal beam 302. The polarization beam splitter 222 may be a cubic PBS (Polarizing Beam Splitter), which is composed of two right-angle prisms, one of which has a special multilayer dielectric film coated on the inclined surface, which can reflect light in a specific polarization direction and allow light in another direction to pass through. In this embodiment, the propagation direction of the reference beam 301 and the propagation direction of the signal beam 302 may be perpendicular to each other.

[0070] See also Figure 3 In one embodiment of the present invention, the reference light module 230 may include a second half-wave plate 231, a first beam expander 232, a first collimating lens 233, a first reflector 234 and a first lens 235. The second half-wave plate 231 may be located on the propagation path of the reference beam 301, and may be used to adjust the polarization direction of the reference beam 301. The first beam expander 232 may be used to receive the adjusted reference beam 301 and perform beam expansion processing on it to expand the diameter of the reference beam 301. The purpose of the beam expansion processing is to obtain better spatial coherence and to match the spot size between the signal light and the reference light to ensure a good interference effect. The first collimating lens 233 may be used to receive the reference beam 301 after the beam expansion processing and perform collimation processing on it to convert the reference beam 31 after the beam expansion processing into parallel light. The collimation processing helps to maintain the consistency of the beam and enables the beam to cover the surface of the entire holographic photosensitive film material more effectively. The first reflector 234 may be used to reflect the reference beam 301 to change its propagation direction. In this embodiment, the optical path of the reflected reference beam 301 is perpendicular to the holographic photosensitive film material 260. The first lens 235 is located in the direction of the reference beam 301 after reflection, and can be used to diverge the reflected reference beam 301 and irradiate the diverged reference beam 301 onto the holographic photosensitive film material 260. The divergence process can make the reference beam 301 evenly illuminate the holographic photosensitive material, and also helps to control the light intensity distribution in the interference area.

[0071] See also Figure 3In one embodiment of the present invention, the signal light module 250 may include a third half-wave plate 251, a second beam expander 252, a second collimating lens 253, a second reflector 254, and a second lens 255. The third half-wave plate 251 may be located on the propagation path of the signal light beam 302, and may be used to adjust the polarization direction of the signal light beam 302. The second beam expander 252 may be used to receive the adjusted signal light beam 302, and perform beam expansion processing on it to expand the diameter of the signal light beam 302. The second collimating lens 253 may be used to receive the signal light beam 302 after beam expansion processing, and perform collimation processing on it to convert the expanded reference light beam 31 into parallel light. The second reflector 254 may be used to reflect the signal light beam 302 to change its propagation direction. In this embodiment, an angle is formed between the optical path of the reflected signal light beam 302 and the scattering film 240, and the angle of the angle is equal to the tilt angle β when the holographic photosensitive film is applied to the optical combiner 120. The second lens 255 is located in the direction of the reflected signal light beam 302 , and can be used to focus the reflected signal light beam 302 and irradiate the focused signal light beam 302 onto the scattering film 240 .

[0072] See also Figure 3 , Figure 4 In one embodiment of the present invention, the scattering film 240 can be attached to one side of the holographic photosensitive film material 260. At this time, the scattering angle of each point on the scattering film 240 is related to its position. During the preparation process, the length of the scattering film 240 and the holographic photosensitive film material 260 are equal, both X. Figure 4 As shown, the distance between the upper vertex of the scattering film 240 and the focal plane of the second lens 255 is L, and the distance between the lower vertex and the focal plane of the second lens 255 is F. In this embodiment, F is the focal length of the second lens 255. When the projection imager 110 in the head-up display system 100 uses a laser light source, and the size D of the eye box 140 required, the scattering angle of each point on the scattering film 240 can be calculated. Taking the upper vertex of the scattering film 240 as the origin, the distance from any point on it to the origin is xi, then the distance R(xi) from the point to the focal plane of the second lens 255 can satisfy the following formula:

[0073] R(xi)=xi·cosβ+L;

[0074] According to the arc center angle formula, the scattering angle θ of a certain point xi is i (xi) can satisfy the following formula:

[0075]

[0076] See also Figure 5In one embodiment of the present invention, when the projection imager 110 in the head-up display system 100 uses a wide-bandwidth light source such as LCD, mini-led, etc., the scattering angle of each point on the scattering film 240 can be obtained according to the required human eye box size D+ΔD. In this embodiment, the wavelength range of the wide-bandwidth light source used by the projection imager 110 is λ±Δλ. Figure 5 As shown, if the wavelength λ′ of the incident light is equal to the wavelength λ of the laser light source during preparation, then the exit angle If the wavelength λ′ of the incident light is not equal to the wavelength λ of the laser light source during preparation, then the exit angle is not equal to the incident angle α. Figure 6 As shown, the wavelength range of the wide bandwidth light source is λ±Δλ, taking the central light as the standard, the incident angle of the central light is The exit angle changes, and the eye box size is D+ΔD, then ΔD satisfies the following formula:

[0077]

[0078] In this embodiment, the scattering angle of each point on the scattering film 240 is in a gradual relationship with the corresponding position. The vertex is the origin, and the distance from the center point on the scattering film 240 to the origin is xi. The distance from the point to the focal plane of the lens satisfies:

[0079] R(xi)=xi·cosβ+L;

[0080] According to the arc center angle formula, the scattering angle θ of point xi is obtained. i (xi):

[0081]

[0082] See also Figure 7 In one embodiment of the present invention, the scattering pattern 240 can also be arranged in parallel with the second lens 255. The parallel reference beam 301 is divergently irradiated to one side of the holographic photosensitive film material through the first lens 235, and the signal beam 302 is irradiated to the other side of the holographic photosensitive film material through the second lens 255 perpendicular to the parallel beam and the scattering pattern 240 close to the second lens 255. In this embodiment, the scattering angle of each point on the scattering pattern 240 remains fixed. At this time, the holographic photosensitive film material is subjected to interference exposure to obtain the desired holographic optical film with directional scattering ability.

[0083] See also Figure 8In one embodiment of the present invention, the head-up display system may include multiple groups of projection imagers 110 and optical combiners 120. In each group of multiple groups of projection imagers 110 and optical combiners 120, the projection imager 110 is projected onto the corresponding optical combiner 120 and directionally scattered to the corresponding area, that is, each group corresponds to a position to display the projection content in a direction, and different groups do not interfere with each other. For example, one group corresponds to the main driving position, and the optical combiner 120 displays high-brightness driving navigation information, which is only visible to the driver within the fixed eye box range. Another group corresponds to the co-pilot position, and the optical combiner 120 displays clear entertainment film and television content, which is only visible to the co-pilot within the fixed eye box range, and the co-pilot information will not interfere with the main driver.

[0084] See also Fig. 9 The present invention also provides a method for preparing a holographic optical film, which may include the following steps:

[0085] Step S100, generating a laser beam, and splitting the laser beam to generate a reference beam and a signal beam;

[0086] Step S200, reflecting the reference beam to one side of the holographic photosensitive film material;

[0087] Step S300, attaching a scattering film to the other side of the holographic photosensitive film material, and reflecting the signal light beam onto the scattering film;

[0088] Step S400: After the signal beam passes through the scattering film, it is irradiated on the holographic photosensitive film material together with the reference beam to perform interference exposure on the holographic photosensitive film material to form a holographic optical film.

[0089] In one embodiment of the present invention, when step S100 is executed, a laser beam is generated, and the laser beam is split to generate a reference beam and a signal beam. Specifically, a laser beam 300 with a specific wavelength and high coherence is first generated by a laser 210. A laser beam 300 with a specific wavelength and high coherence is generated. The laser 210 can be a helium-neon (He-Ne) laser, an argon ion laser, or a solid-state laser. Then, the laser beam 300 is received by a beam splitting module 220, and the laser beam 300 is split to form a reference beam 301 and a signal beam 302.

[0090] In one embodiment of the present invention, when step S200 is executed, the reference beam is reflected to one side of the holographic photosensitive film material. Specifically, the reference beam 301 is reflected to one side of the holographic photosensitive film material 260 by the reference light module 230. In this embodiment, first, the polarization direction of the reference beam 301 is adjusted by the second half-wave plate 231. Then, the adjusted reference beam 301 is expanded by the first beam expander 232, and the expanded reference beam 301 is collimated by the first collimating lens 233 to convert the reference beam 31 into parallel light. Then, the reference beam 301 is reflected by the first reflector 234 to change its propagation direction. In this embodiment, the optical path of the reflected reference beam 301 is perpendicular to the holographic photosensitive film material 260. Finally, the reflected reference beam 301 is diverged by the first lens 235, and the diverged reference beam 301 is irradiated onto the holographic photosensitive film material 260.

[0091] In one embodiment of the present invention, when step S300 is executed, a scattering film 240 is disposed on the other side of the holographic photosensitive film material, and the signal light beam is reflected onto the scattering film 240. Specifically, when the scattering film 240 is attached to one side of the holographic photosensitive film material 260, the scattering angle of each point thereon is related to its position. In this embodiment, first, the polarization direction of the signal light beam 302 is adjusted by the third half-wave plate 251. Then, the adjusted signal light beam 302 is expanded by the second beam expander 252, and the expanded signal light beam 302 is collimated by the second collimating lens 253 to convert the expanded reference light beam 31 into parallel light. Then, the signal light beam 302 is reflected by the second reflector 254 to change its propagation direction. In this embodiment, the angle between the optical path of the reflected signal light beam 302 and the scattering film 240 is β. Finally, the reflected signal light beam 302 is focused by the second lens 255 , and the focused signal light beam 302 is irradiated onto the scattering film 240 .

[0092] In one embodiment of the present invention, when step S400 is executed, the signal light beam passes through the scattering film and irradiates the holographic photosensitive film material simultaneously with the reference light beam, so as to perform interference exposure on the holographic photosensitive film material to form a holographic optical film. Specifically, the signal light beam 302 passes through the scattering film 260 and forms interference fringes with the reference light beam 301 on the holographic photosensitive film material 260, thereby realizing interference exposure on the holographic photosensitive film material 260 to form the desired holographic optical film with directional scattering capability.

[0093] In summary, the present invention discloses a holographic optical film, a preparation method, a preparation system and a display system for its application. The holographic optical film has the characteristics of simple and light structure and low cost, and at the same time exhibits excellent display performance and optical perspective effect, which greatly promotes the wide application and development of HUD technology in multiple fields such as vehicle-mounted / aircraft-mounted equipment, entertainment display and exhibition. Different from the technical path based on the traditional geometric optical principle, the present invention adopts directional scattering holographic film imaging technology, which theoretically achieves 100% transmittance and 100% diffraction efficiency. The directional scattering holographic film formed by a specific preparation process can efficiently generate images, and these images are only visible to the driver, ensuring driving safety while improving user experience. In addition, since the image is directly projected onto the windshield, the entire optical path design is more concise and compact, further reducing the physical size of the system, and providing convenient conditions for integrated installation. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0094] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A holographic optical film, characterized in that: The holographic optical film is prepared by interfering a reference light beam and a signal light beam on a holographic photosensitive film material, and the scattering angles on the holographic optical film are in a gradual relationship; The reference beam and the signal beam are formed by splitting a laser beam, the reference beam is irradiated on one side of the holographic photosensitive film material, and the signal beam is irradiated on the other side of the holographic photosensitive film material after passing through a scattering film.

2. A method for preparing a holographic optical film, characterized in that: For preparing the holographic optical film as claimed in claim 1, the preparation method comprises: Generate a laser beam, and split the laser beam to generate a reference beam and a signal beam; Reflecting the reference beam to one side of the holographic photosensitive film material; Laminating a scattering film to the other side of the holographic photosensitive film material, and reflecting the signal light beam onto the scattering film; The signal light beam passes through the scattering film and is irradiated onto the holographic photosensitive film material simultaneously with the reference light beam, so as to perform interference exposure on the holographic photosensitive film material and form a holographic optical film.

3. A system for preparing a holographic optical film, characterized in that: For preparing the holographic optical film as claimed in claim 1, the preparation system comprises: A laser for generating a laser beam; A beam splitting module, disposed on the propagation path of the laser beam, for splitting the laser beam to generate a reference beam and a signal beam; A reference light module, disposed on the propagation path of the reference light beam, and used for reflecting the reference light beam to one side of the holographic photosensitive film material; A scattering film, located on the other side of the holographic photosensitive film material; A signal light module, disposed on the propagation path of the signal light beam, and used for reflecting the signal light beam onto the scattering film; Wherein, after passing through the scattering film, the signal light beam is irradiated onto the holographic photosensitive film material simultaneously with the reference light beam, so as to perform interference exposure on the holographic photosensitive film material to form a holographic optical film.

4. The system for preparing a holographic optical film according to claim 3, characterized in that: The beam splitting module comprises: A first half-wave plate, located on the propagation path of the laser beam, and used to adjust the polarization direction of the laser beam; and The polarization beam splitter is located on the propagation path of the laser beam and is used to perform beam splitting processing on the adjusted laser beam to generate the reference beam and the signal beam.

5. The system for preparing a holographic optical film according to claim 3, characterized in that: The reference optical module comprises: A second half-wave plate, located on the propagation path of the reference beam, and adjusting the polarization direction of the reference beam; A first beam expander, used for performing beam expansion processing on the adjusted reference beam; A first collimating lens, used for collimating the reference beam after beam expansion; a first reflecting mirror, used for reflecting the reference beam after the collimation process, wherein a propagation path of the reflected reference beam is perpendicular to the holographic photosensitive film material; and The first lens is used to diverge the reflected reference light beam and irradiate it onto the holographic photosensitive film material.

6. The system for preparing a holographic optical film according to claim 3, characterized in that: The signal optical module comprises: A third half-wave plate, located on the propagation path of the signal light beam, and adjusting the polarization direction of the signal light beam; A second beam expander, used for performing beam expansion processing on the adjusted signal light beam; A second collimating lens, used for collimating the signal light beam after beam expansion; A second reflector, used for reflecting the collimated signal light beam; and The second lens is used to focus the reflected signal light beam and irradiate it onto the scattering film.

7. The system for preparing a holographic optical film according to claim 3, characterized in that: The scattering film is attached to the other side of the holographic photosensitive film material, and the scattering angle of each point on the scattering film is related to its position.

8. The system for preparing a holographic optical film according to claim 7, characterized in that: The scattering angle θ of each point on the scattering film i (xi) satisfies the following formula: Wherein, xi represents the distance between a certain point on the scattering film and the origin, L represents the distance between the origin and the focal plane of the second lens, and D represents the scattering range of the certain point on the focal plane of the second lens.

9. The system for preparing a holographic optical film according to claim 3, characterized in that: The scattering film is parallel to the second lens, and the scattering angle of each point on the scattering film is the same.

10. A display system, characterized in that: include: A projection imager for generating real image light; An optical combiner, used for performing directional scattering imaging on the real image light; Wherein, the optical combiner is the holographic optical film described in claim 1.

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