Transmissive achromatic flat lens and method therefor and use thereof

Abstract

A transmissive achromatic flat lens and a method therefor and a use thereof. The transmissive achromatic flat lens comprises: a first cholesteric liquid crystal (CLC) volume holographic element, provided with an alignment layer for recording lens information and a CLC layer stacked on the alignment layer, wherein the helical axis of the CLC layer is perpendicular to the device surface of the first CLC volume holographic element, and the CLC layer is used for reflecting first circularly polarized light to modulate the propagation direction of the first circularly polarized light and transmitting second circularly polarized light having the sense opposite to the sense of the first circularly polarized light to be emitted; and a reflective-transmissive element for reflecting a part of light and transmitting the other part of light, provided on the light reflecting side of the first CLC volume holographic element, and used for partially transmitting incident light to form the first circularly polarized light incident into the first CLC volume holographic element, and partially reflecting the first circularly polarized light reflected by the first CLC volume holographic element to form the second circularly polarized light to be incident on the first CLC volume holographic element.

Description

Transmissive achromatic flat lens and method and application thereof

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 202311835299.8, filed on December 27, 2023, entitled “Transmissive achromatic flat lens, method and application thereof”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of cholesteric liquid crystal, and in particular to a transmissive achromatic flat lens and a method and application thereof. Background Art

[0004] Currently, most existing lenses suffer from broadband dispersion. For example, refractive optics suffers from dispersion; diffractive optics suffers from even more severe dispersion issues; and traditional holographic optics is extremely sensitive to both wavelength and angle of incidence. While reflective optics offers broadband achromaticity, eliminating dispersion issues, it is inconvenient to use and difficult to implement in imaging systems.

[0005] To address the dispersion problem, traditional technical solutions typically combine diffractive and refractive optical devices, leveraging the complementary dispersion properties of diffractive and refractive optics to offset chromatic aberration to a certain extent. However, due to factors such as the material's refractive index and / or Abbe number, this diffractive-refraction combination struggles to completely offset chromatic aberration, and the dispersion problem still persists. Furthermore, traditional refractive optical devices mostly achieve specific phase distributions by constructing curved surfaces, but these devices are typically bulky and heavy, resulting in a larger and heavier diffractive-refraction combination, making it unsuitable for imaging applications.

[0006] Summary of the Invention

[0007] According to various embodiments of the present application, a transmissive achromatic flat lens, a method for the same, and an application thereof are provided.

[0008] The present application provides a transmissive achromatic flat lens, comprising:

[0009] a first CLC volume hologram element having an alignment layer for recording lens information and a cholesteric liquid crystal layer stacked on the alignment layer, wherein the helical axis of the cholesteric liquid crystal layer is perpendicular to a device surface of the first CLC volume hologram element, and is configured to reflect a first circularly polarized light to modulate a propagation direction of the first circularly polarized light, and transmit a second circularly polarized light having a handing direction opposite to that of the first circularly polarized light for output; and

[0010] A transflective element for reflecting a portion of the light and transmitting another portion of the light is disposed on the light-reflecting side of the first CLC volume hologram element. The element is configured to partially transmit the incident light to form a first circularly polarized light incident on the first CLC volume hologram element, and partially reflect the first circularly polarized light reflected by the first CLC volume hologram element to form the second circularly polarized light incident on the first CLC volume hologram element.

[0011] In one embodiment of the present application, there are multiple first CLC volume hologram elements, and the multiple first CLC volume hologram elements are stacked on each other.

[0012] In one embodiment of the present application, the reflective element is a semi-reflective and semi-transparent film attached to the first CLC volume holographic element.

[0013] In one embodiment of the present application, the transmissive achromatic flat lens further includes a leakage light eliminating component, which is arranged on the light-transmitting side of the first CLC volume hologram element and is used to eliminate the first circularly polarized light leaking through the first CLC volume hologram element and transmit the second circularly polarized light passing through the first CLC volume hologram element.

[0014] In one embodiment of the present application, the leakage light elimination component includes a first linear polarization element for absorbing first linear polarized light and transmitting second linear polarized light, and a first phase delay element located between the first CLC volume hologram element and the first linear polarization element, wherein the first phase delay element is used to convert the first circularly polarized light into the first linear polarized light, and convert the second circularly polarized light into the second linear polarized light.

[0015] In one embodiment of the present application, the first linear polarization element is a linear polarizer; the first phase delay element is a quarter wave plate; the first linear polarization element and the first phase delay element are sequentially stacked on the light-transmitting side of the first CLC volume holographic element.

[0016] In one embodiment of the present application, the transmissive achromatic flat lens further includes a polarizing component, which is disposed on the light incident side of the reflective element and is used to polarize the incident light into the first circularly polarized light for incident into the reflective element.

[0017] In one embodiment of the present application, the polarizing component includes a second linear polarization element for absorbing the second linear polarization light and transmitting the first linear polarization light, and a second phase delay element located between the second linear polarization element and the reflective element. The second phase delay element is used to convert the first linear polarization light transmitted through the second linear polarization element into the first circular polarization light to be incident on the reflective element, and to convert the second circular polarization light reflected toward the light incident side through the reflective element into the second linear polarization light to be absorbed by the second linear polarization element.

[0018] In one embodiment of the present application, the transmissive achromatic flat lens further includes a second CLC volume holographic element disposed between the polarizing component and the reflective element, configured to transmit the first circularly polarized light to propagate to the reflective element, and reflect the second circularly polarized light from the reflective element to modulate the propagation direction of the second circularly polarized light.

[0019] According to another aspect of the present application, the present application further provides an optical lens, comprising any of the above-mentioned transmissive achromatic flat lenses.

[0020] According to another aspect of the present application, the present application further provides an imaging module, comprising:

[0021] Photosensitive components; and

[0022] The above-mentioned optical lens is arranged on the photosensitive side of the photosensitive component.

[0023] According to another aspect of the present application, the present application further provides a method for manufacturing a transmissive achromatic flat lens, comprising the steps of:

[0024] Manufacturing a first CLC volume hologram element, wherein the first CLC volume hologram element comprises an alignment layer for recording lens information and a cholesteric liquid crystal layer stacked on the alignment layer, wherein the helical axis of the cholesteric liquid crystal layer is perpendicular to a device surface of the first CLC volume hologram element; and

[0025] A reflective element is disposed on the reflective side of the first CLC volume hologram element to reflect first circularly polarized light emitted from the reflective element via the curved surface of the first CLC volume hologram element to modulate the propagation direction of the first circularly polarized light, and to transmit second circularly polarized light emitted from the reflective element and having a rotation direction opposite to that of the first circularly polarized light.

[0026] In one embodiment of the present application, the method for manufacturing the transmissive achromatic flat lens further includes the steps of:

[0027] A light leakage eliminating component is disposed on the light transmission side of the first CLC volume holographic element to eliminate the first circularly polarized light leaking through the first CLC volume holographic element and transmit the second circularly polarized light passing through the first CLC volume holographic element.

[0028] According to one embodiment of the present application, the method for manufacturing the transmissive achromatic flat lens further includes the steps of:

[0029] The polarizing element is disposed on the light incident side of the reflective element to polarize the incident light into the first circularly polarized light to enter the reflective element and absorb the second circularly polarized light reflected toward the light incident side by the reflective element.

[0030] In one embodiment of the present application, the method for manufacturing the transmissive achromatic flat lens further includes the steps of:

[0031] A second CLC volume hologram is disposed between the polarizing element and the reflective element to transmit the first circularly polarized light to propagate to the reflective element and to reflect the second circularly polarized light from the reflective element to modulate the propagation direction of the second circularly polarized light.

[0032] In one embodiment of the present application, the step of manufacturing the first CLC volume holographic element comprises the following steps:

[0033] coating a liquid crystal alignment material on a light-transmitting substrate;

[0034] exposing the liquid crystal alignment material through a double-beam interference exposure process to form an alignment layer that records lens information in the form of an alignment direction; and

[0035] A cholesteric liquid crystal material is coated on the alignment layer to form a cholesteric liquid crystal layer.

[0036] According to another aspect of the present application, the present application further provides a method for achromatic transmission imaging, comprising the steps of:

[0037] transmitting the first circularly polarized light through the anti-transmission element to propagate to the first CLC volume holographic element;

[0038] The curved surface reflects the first circularly polarized light through the first CLC volume holographic element to propagate back to the anti-transmissive element;

[0039] Reflecting the first circularly polarized light through the anti-transmissive element to form a second circularly polarized light having a rotation direction opposite to that of the first circularly polarized light, so as to propagate to the first CLC volume hologram element again; and

[0040] The second circularly polarized light is transmitted through the first CLC volume hologram element to form an image.

[0041] In one embodiment of the present application, before the step of transmitting the first circularly polarized light through the anti-transmission element to propagate to the first CLC volume holographic element, the following steps are further included:

[0042] The incident light is polarized into the first circularly polarized light so as to be incident on the light incident surface of the reflective element.

[0043] According to one embodiment of the present application, the step of polarizing the incident light into the first circularly polarized light so as to allow the light to enter from the light incident surface of the reflective element includes the following steps:

[0044] absorbing the second linearly polarized light in the incident light and transmitting the first linearly polarized light in the incident light;

[0045] converting the transmitted first linearly polarized light into first circularly polarized light for incident on the anti-transmissive element, so that a portion of the first circularly polarized light passes through the anti-transmissive element to be incident on the first CLC volume hologram element, and another portion of the first circularly polarized light is reflected by the anti-transmissive element to form second circularly polarized light propagating toward the light incident side; and

[0046] The second circularly polarized light propagating toward the incident side is converted into the second linearly polarized light to be absorbed.

[0047] In one embodiment of the present application, the achromatic transmission imaging method further includes the steps of:

[0048] The first circularly polarized light leaked through the first CLC volume hologram element is eliminated, and the second circularly polarized light transmitted through the first CLC volume hologram element is transmitted.

[0049] In one embodiment of the present application, the step of eliminating the first circularly polarized light leaking through the first CLC volume hologram element and transmitting the second circularly polarized light passing through the first CLC volume hologram element comprises the following steps:

[0050] converting the first circularly polarized light and the second circularly polarized light transmitted through the first CLC volume hologram element into the first linearly polarized light and the second linearly polarized light respectively; and

[0051] The first linear polarized light is absorbed and the second linear polarized light is transmitted.

[0052] In summary, the transmissive achromatic flat lens of the present application and its method and application can completely solve the dispersion problem while modulating light in a transmissive manner, so as to perfectly replace the application of traditional curved lenses in optical imaging.

[0053] In one embodiment of the present application, the transmissive achromatic flat lens can perfectly inherit the achromatic property of reflective optics, so as to completely solve the dispersion problem.

[0054] In one embodiment of the present application, the broadband of the transmissive achromatic flat lens can cover the entire visible light, which is convenient for application in white light imaging systems.

[0055] In one embodiment of the present application, the transmissive achromatic flat lens can utilize the optical properties of CLC (Cholesteric liquid crystal) to achieve insensitivity to the angle of incident light, has a considerable tolerance, and is relatively practical and applicable.

[0056] In one embodiment of the present application, the transmissive achromatic flat lens can have a larger aperture and a stronger focusing capability.

[0057] Furthermore, the transmissive achromatic flat lens, method, and application provided herein achieve the aforementioned objectives without the need for expensive materials or complex structures. Therefore, this application successfully and effectively provides a solution that not only provides a simple transmissive achromatic flat lens, method, and application thereof, but also increases the practicality and reliability of the transmissive achromatic flat lens, method, and application thereof.

[0058] The details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to better describe and illustrate the embodiments and / or examples of the inventions disclosed herein, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the accompanying drawings should not be considered to limit the scope of the disclosed inventions, the presently described embodiments and / or examples, and any of the best modes currently understood for these inventions.

[0060] FIG1 is a schematic structural diagram of a transmissive achromatic flat lens according to an embodiment of the present application;

[0061] FIG2 shows a schematic diagram of the folded optical path of the transmissive achromatic flat lens according to the above embodiment of the present application;

[0062] FIG3 shows an example of a first CLC volume holographic element in a transmissive achromatic flat lens according to the above embodiment of the present application;

[0063] FIG4 is a schematic diagram showing a reflection spectrum of the first CLC volume holographic element according to the above example of the present application;

[0064] FIG5 shows a specific example of a transmissive achromatic flat lens according to the above embodiment of the present application;

[0065] FIG6 shows a deformation example of the transmissive achromatic flat lens according to the above embodiment of the present application;

[0066] FIG7 is a block diagram of an imaging module according to an embodiment of the present application;

[0067] FIG8 is a schematic flow chart of a method for manufacturing a transmissive achromatic flat lens according to an embodiment of the present application;

[0068] FIG9 shows an example of a step of manufacturing a first CLC volume holographic element in the method for manufacturing a transmissive achromatic flat lens according to the above embodiment of the present application;

[0069] FIG10 is a schematic flow chart of a method for achromatic transmission imaging according to an embodiment of the present application;

[0070] FIG11 shows an example of a polarization step in the achromatic transmission imaging method according to the above embodiment of the present application;

[0071] FIG. 12 shows an example of a light leakage elimination step in the achromatic transmission imaging method according to the above embodiment of the present application. DETAILED DESCRIPTION

[0072] The following description is intended to disclose the present application and enable those skilled in the art to implement the present application. The preferred embodiments described below are for illustrative purposes only, and those skilled in the art may readily conceive of other obvious variations. The basic principles of the present application defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present application.

[0073] Those skilled in the art should understand that, in the disclosure of this application, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be understood as limiting this application.

[0074] In this application, the term "a" or "an" in the claims and the specification should be understood as "one or more." That is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple. Unless the disclosure of this application clearly indicates that the number of the element is only one, the term "a" or "an" should not be understood as unique or singular, and the term "a" or "an" should not be understood as a limitation on quantity.

[0075] In the description of this application, it should be understood that "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of this application, it should be noted that, unless otherwise clearly specified and limited, "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through a medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0076] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0077] Considering that existing diffractive and refractive combination schemes can offset chromatic aberration to a certain extent by leveraging the complementary dispersion properties of diffractive and refractive optics, they are limited by factors such as the material's refractive index and / or Abbe number, making it difficult to completely offset chromatic aberration, and the dispersion problem still exists. Therefore, this application creatively proposes a transmissive achromatic flat lens, method, and application thereof. This lens can completely resolve the dispersion problem while also modulating light in a transmissive manner, thereby perfectly replacing the application of traditional curved lenses in optical imaging.

[0078] Specifically, referring to Figures 1 to 5 of the accompanying drawings of the present application, a transmissive achromatic flat lens 1 is provided according to one embodiment of the present application. The transmissive flat lens 1 may include a transmissive element 10 for reflecting a portion of light and transmitting another portion of light, and a first CLC volume holographic element 20. The transmissive element 10 is disposed on the light-reflecting side of the first CLC volume holographic element 20.

[0079] More specifically, as shown in Figures 1 and 2, the anti-transmissive element 10 is configured to partially transmit incident light to form first circularly polarized light that is incident on the first CLC volume hologram element 20, and partially reflect the first circularly polarized light reflected by the first CLC volume hologram element 20 to form second circularly polarized light having a handing direction opposite to that of the first circularly polarized light, which is then incident on the first CLC volume hologram element 20. The first CLC volume hologram element 20 includes an alignment layer 21 for recording lens information and a cholesteric liquid crystal layer 22 stacked on the alignment layer 21. The cholesteric liquid crystal layer 22 has a helical axis perpendicular to the device surface of the first CLC volume hologram element 20. The anti-transmissive element 10 is configured to reflect the first circularly polarized light partially transmitted by the anti-transmissive element 10 to modulate the propagation direction of the first circularly polarized light so that the light propagates back to the anti-transmissive element 10, and transmit the second circularly polarized light partially reflected by the anti-transmissive element 10.

[0080] For example, as shown in Figures 1 and 2, the reflective element 10 has a light incident surface 101 and a light exiting surface 102 arranged in opposite directions, and the first CLC volume hologram element 20 is located on the light exiting side of the reflective element 10. Thus, as shown in Figure 2, first circularly polarized light incident from the light incident surface 101 first partially transmits through the reflective element 10 to form first circularly polarized light emitted from the light exiting surface 102 and propagates to the first CLC volume hologram element 20. Thereafter, the first circularly polarized light is reflected by the curved surface of the first CLC volume hologram element 20, modulating the propagation direction and propagating back to the light exiting surface 102. Subsequently, the first circularly polarized light incident from the light exiting surface 102 is partially reflected by the reflective element 10 to form second circularly polarized light emitted from the light exiting surface 102. Finally, the second circularly polarized light emitted from the light exiting surface 102 propagates back to the first CLC volume hologram element 20 and transmits through the first CLC volume hologram element 20. In other words, the transmissive achromatic flat-plate lens 1 of the present application forms folded optics through the reflective element 10 and the first CLC volume holographic element 20, converting the reflective system into a transmissive system while retaining the broadband achromatic characteristics of the reflective optics, so that it is equivalent to a transmissive flat-plate optical device as a whole. It can not only completely solve the dispersion problem, but also modulate light in a transmissive manner, so as to perfectly replace the application of traditional curved lenses in optical imaging.

[0081] It is worth noting that the CLC mentioned in this application refers to cholesteric liquid crystal (CLC), a material with strong polarization selectivity. It completely reflects circularly polarized light of a specific rotational direction at an angle that satisfies Bragg's law, while completely transmitting circularly polarized light of another rotational direction. Furthermore, the optical properties of the first CLC volume holographic element 20 mentioned in this application are determined by the alignment layer 21. Based on the specific alignment layer design and exposure, the CLC volume holographic element 20 can have an optical power similar to that of a lens, and is a planar optical element capable of modulating reflected light.

[0082] Furthermore, because the cholesteric liquid crystal layer 22 of the first CLC volume hologram element 20 has an angular reflection bandwidth, when using a transmissive achromatic flat lens 1, the incident angle of the first circularly polarized light transmitted through the transflective element 10 on the device surface of the first CLC volume hologram element 20 (i.e., the angle between the first circularly polarized light and the helical axis of the cholesteric liquid crystal layer 22) must be within this angular reflection bandwidth. It can be understood that the cholesteric liquid crystal layer 22 can be considered to be composed of a one-dimensional Bragg lattice along the helical axis and mirror surfaces perpendicular to the helical axis: the Bragg lattice determines the reflection center wavelength, and the mirror surfaces determine the reflection imaging law. The reflection imaging law of the cholesteric liquid crystal layer 22 follows the principle that the angles between the incident and reflected surfaces and the mirror surface normal are equal, which is the same as the law of conventional Fresnel mirror reflection. Therefore, the reflection of the first CLC volume hologram element 20 of the present application is within its angular reflection bandwidth and is independent of wavelength. In other words, the reflection of the first CLC volume hologram element 20 of the present application is achromatic.

[0083] It is understandable that, unlike traditional volume holography, the first CLC volume holographic element 20 of the present application can record lens information in the alignment layer 21 by means of dual-beam interference, so that the reflective surface of the cholesteric liquid crystal layer 22 is changed from a traditional plane to a curved surface, that is, its reflective surface is not always perpendicular to the helical axis, but this does not affect the basic law of reflective imaging. It is equivalent to forming a reflective lens for curved reflection of the first circularly polarized light emitted from the light-emitting surface 102.

[0084] 2 and 5 , taking right-handed circularly polarized light (hereinafter referred to as RCP) as the first circularly polarized light and left-handed circularly polarized light (hereinafter referred to as LCP) as the second circularly polarized light as an example: the cholesteric liquid crystal layer 22 of the first CLC volume holographic element 20 is doped with a corresponding chiral material, that is, the cholesteric liquid crystal layer 22 is configured to reflect RCP and transmit LCP. In this way, the RCP incident from the light incident surface 101 remains as RCP after passing through the anti-transmissive element 10, and is emitted from the light emitting surface 102 and propagates to the first CLC volume hologram element 20. Next, the RCP is reflected by the curved surface of the first CLC volume hologram element 20, and after the propagation direction is modulated, it remains as RCP and propagates back to the light emitting surface 102. Thereafter, the RCP incident from the light emitting surface 102 is reflected by the anti-transmissive element 10 to change the handedness and form LCP emitted from the light emitting surface 102. Finally, the LCP emitted from the light emitting surface 102 propagates again to the first CLC volume hologram element 20, and remains as LCP after passing through the first CLC volume hologram element 20. It is understood that in other examples of the present application, the first circularly polarized light may also be left-handed circularly polarized light (LCP); correspondingly, the second circularly polarized light may be right-handed circularly polarized light (RCP), which will not be described in detail herein.

[0085] It is noteworthy that the first CLC volume hologram element 20 of the present application retains the reflective properties of CLC, namely, optical rotation reflection and band reflection; thus, multi-layer stacking can also expand bandwidth. At the same time, the first CLC volume hologram element 20 of the present application also retains the same tolerance to incident angles. These are the key differences between the first CLC volume hologram element 20 of the present application and traditional volume holographic devices. However, the first CLC volume hologram element 20 of the present application also inherits the advantages of traditional volume holography: such as the ability to record large-aperture lens information to achieve large focusing or divergence capabilities. It is understandable that the tolerance to incident angles comes from the optical properties of the cholesteric liquid crystal itself. As long as the cholesteric liquid crystal layer 22 is sufficiently thick, it will not be overly sensitive to the incident angle.

[0086] However, although the cholesteric liquid crystal layer 22 in the first CLC volume holographic element 20 exhibits band-like reflection, a single cholesteric liquid crystal layer 22 can only reflect a band with a theoretical width of several tens of nanometers. For example, taking the reflection of light with a central wavelength of 550 nanometers as an example, the pitch of a single cholesteric liquid crystal layer 22 is approximately 550 / 1.5 = 360 nanometers. If the refractive index difference is 0.2 × 360 = 72 nanometers, the reflection band is roughly sufficient to cover one color of the display.

[0087] Therefore, to cover the visible light band from 400 nm to 700 nm, as shown in FIG3 , the transmissive achromatic flat lens 1 of the present invention can include multiple first CLC volume hologram elements 20, with multiple first CLC volume hologram elements 20 stacked one on top of the other. For example, the chiral material doping concentrations in the cholesteric liquid crystal layers 22 of the multiple first CLC volume hologram elements 20 can differ, thereby expanding the reflection bandwidth, ensuring that the light paths of various colors completely overlap, completely eliminating chromatic aberration, and thoroughly resolving the dispersion problem. It is understood that the helical pitch of the cholesteric liquid crystal is inversely proportional to the doping concentration of the chiral material in the liquid crystal. That is, the greater the doping concentration of the chiral material in the liquid crystal, the smaller the helical pitch of the cholesteric liquid crystal, and the corresponding smaller the reflection wavelength. Therefore, as shown in FIG4 , the transmissive achromatic flat lens 1 of the present invention can expand the reflection bandwidth by using multiple cholesteric liquid crystal layers 22 with different chiral material doping concentrations, so as to cover the entire visible light band from 400 nm to 700 nm.

[0088] Furthermore, although the first CLC volume hologram element 20 of the present application can reflect the vast majority of the first circularly polarized light back to the anti-transmissive element 10, a small amount of the first circularly polarized light still passes through the first CLC volume hologram element 20, resulting in reflected light leakage, which affects imaging quality. Therefore, as shown in FIG2 and FIG5 , to eliminate the interference of reflected light leakage, the transmissive achromatic flat lens 1 of the present application can further include a light leakage elimination component 30. The light leakage elimination component 30 is disposed on the light-transmitting side of the first CLC volume hologram element 20 and is used to eliminate the first circularly polarized light leaking through the first CLC volume hologram element 20 and transmit the second circularly polarized light that has passed through the first CLC volume hologram element 20 as the output light.

[0089] Optionally, as shown in FIG5 , the leakage light elimination assembly 30 includes a first linear polarization element 31 for absorbing the first linear polarization light and transmitting the second linear polarization light, and a first phase retarder 32 located between the first CLC volume hologram 20 and the first linear polarization element 31. The first phase retarder 32 is configured to convert the first circularly polarized light into the first linear polarization light and the second circularly polarized light into the second linear polarization light. In this manner, the first circularly polarized light leaking through the first CLC volume hologram 20 first passes through the first phase retarder 32 to be converted into the first linear polarization light, and then passes through the first linear polarization element 31 to be absorbed, thereby preventing the leaked first circularly polarized light from interfering with the imaging quality. Meanwhile, the second circularly polarized light passing through the first CLC volume hologram 20 is converted into the second linear polarization light upon passing through the first phase retarder 32, and then passes through the first linear polarization element 31 intactly as the output light, thereby ensuring that the second circularly polarized light passing through the first CLC volume hologram 20 is not affected. It can be understood that the polarization direction of the second linear polarized light mentioned in the present application is perpendicular to the polarization direction of the first linear polarized light; for example, the first linear polarized light can be implemented as one of P-polarized light and S-polarized light; accordingly, the second linear polarized light is implemented as the other of P-polarized light and S-polarized light.

[0090] For example, the first linear polarization element 31 may be, but is not limited to, implemented as a linear polarizer, and the first phase delay element 32 may be, but is not limited to, implemented as a quarter-wave plate.

[0091] Optionally, as shown in FIG1 and FIG2 , the first phase delay element 32 and the first linear polarizer 31 are sequentially stacked on the light-transmitting side of the first CLC volume hologram element 20 so as to protect the light-transmitting surface of the first CLC volume hologram element 20 .

[0092] According to the above-mentioned embodiment of the present application, as shown in Figures 2 and 5, the transmissive achromatic flat lens 1 may further include a polarizing component 40, which is disposed on the light incident side of the reflective element 10 and is used to polarize the incident light into the first circularly polarized light so as to be incident into the reflective element 10 through the light incident surface 101. It will be understood that in the application environment of the transmissive achromatic flat lens 1 of the present application, the incident light is generally white light rather than the first circularly polarized light, and the polarizing component 40 of the present application is capable of polarizing the incident light into the first circularly polarized light to ensure that the light propagates according to the designed folded optical path.

[0093] It is worth noting that while the first circularly polarized light polarized by the polarizing component 40 partially transmits through the reflective element 10 to propagate to the first CLC volume holographic element 20, a portion of the light will be reflected by the reflective element 10 or other interfaces to form second circularly polarized light that propagates back to the polarizing component 40. This light is easily reflected back into the folded optical path by the polarizing component 40 to form stray light. To solve this problem, as shown in Figures 2 and 5, the polarizing component 40 of the present application may include a second linear polarizing element 41 for absorbing the second linear polarized light and transmitting the first linear polarized light, and a second phase delay element 42 located between the second linear polarizing element 41 and the reflective element 10. The second phase delay element 42 is used to convert the first linear polarized light transmitted by the second linear polarizing element 41 into the first circularly polarized light for injection into the reflective element 10, and convert the second circularly polarized light reflected by the reflective element 10 toward the light incident side into the second linear polarized light for absorption by the second linear polarizing element 41.

[0094] 5 , the second linear polarized light in the incident light will be absorbed by the second linear polarization element 41, while the first linear polarized light in the incident light will pass through the second linear polarization element 41 to be converted into the first circular polarized light via the second phase delay element 42 and propagate to the reflective element 10; a portion of the first circular polarized light will pass through the reflective element 10 to propagate to the first CLC volume hologram element 20 for folded optical imaging; at the same time, another portion of the first circular polarized light will be reflected by the reflective element 10 to form the second circular polarized light and propagate back to the second phase delay element 42; finally, the second circular polarized light propagating back to the second phase delay element 42 will be converted into the first linear polarized light and absorbed by the second linear polarization element 41, thereby eliminating stray light.

[0095] Optionally, as shown in FIG1 and FIG2 , the second linear polarizer 41 and the second phase delay element 42 in the polarizing assembly 40 are sequentially stacked on the light incident surface 101 of the reflective element 10 to protect the reflective element 10 .

[0096] Preferably, as shown in FIG1 , the polarizing element 40, the reflective element 10, the first CLC volume holographic element 20 and the leakage light elimination element 30 are assembled into an integral device, that is, the device is implemented as a transmissive flat-panel imaging optical device as a whole, which is more convenient to use in optical imaging than a traditional curved lens.

[0097] In a specific example of the present application, as shown in FIG5 , the reflective element 10 in the transmissive achromatic flat lens 1 of the present application can be implemented as a semi-reflective and semi-transmissive film 100 attached to the first CLC volume holographic element 20 . Thus, although a portion of the light in the RCP incident from the light incident surface 101 will be reflected by the semi-reflective semi-transparent film 100 and lost, another portion of the light in the RCP will still pass through the semi-reflective semi-transparent film 100 and propagate to the first CLC volume hologram element 20; then, the RCP is reflected by the curved surface of the first CLC volume hologram element 20 so as to remain as the RCP after modulating the propagation direction and propagate back to the light exit surface 102 of the semi-reflective semi-transparent film 100; thereafter, a portion of the light in the RCP incident from the light exit surface 102 will be reflected by the semi-reflective semi-transparent film 100 so as to change the rotation direction and form the LCP emitted from the light exit surface 102; meanwhile, another portion of the light in the RCP incident from the light exit surface 102 will pass through the semi-reflective semi-transparent film 100 and be lost; finally, the LCP emitted from the light exit surface 102 propagates to the first CLC volume hologram element 20 again so as to remain as the LCP after passing through the first CLC volume hologram element 20.

[0098] It is worth noting that in a modified example of the present application, as shown in FIG6 , the transmissive achromatic flat lens 1 of the present application may further include a second CLC volume hologram element 50, which is disposed between the polarizing assembly 40 and the transflective element 10 and is configured to transmit the first circularly polarized light for propagation to the transflective element 10 and reflect the second circularly polarized light from the transflective element 10 to modulate the propagation direction of the second circularly polarized light. In this way, in addition to utilizing the first circularly polarized light transmitted through the transflective element 10 for modulated imaging, the transmissive achromatic flat lens 1 of the present application may also utilize the second circularly polarized light reflected from the transflective element 10 for modulated imaging, thereby improving light energy utilization.

[0099] Preferably, the polarizing element 40, the second CLC volume hologram element 50, the anti-transmissive element 10, the first CLC volume hologram element 20, and the light leakage elimination assembly 30 are sequentially stacked and bonded to form an integrated device, that is, the entire device is implemented as a transmissive flat-panel imaging optical device, which is more convenient to use in optical imaging than traditional curved lenses. In particular, in this modified example of the present application, the polarizing element 40 and the light leakage elimination assembly 30 can have the same structure, making their functions interchangeable, ensuring that both sides of the transmissive achromatic flat-panel lens 1 can serve as the light incident side, reducing its usage restrictions.

[0100] According to another aspect of the present application, as shown in Figure 7, an embodiment of the present application further provides an imaging module, which may include a photosensitive component 2 and an optical lens 3 having the above-mentioned transmissive achromatic flat lens 1, and the optical lens 3 is located on the photosensitive side of the photosensitive component 2, so as to utilize the transmissive achromatic flat lens 1 to replace the traditional lens to achieve high-quality and clean white light imaging.

[0101] It is worth noting that the optical lens 3 mentioned in this application can include only the transmissive achromatic flat lens 1, or can be composed of the transmissive achromatic flat lens 1 and a conventional lens. Furthermore, in addition to being used for imaging modulation within this imaging module, the optical lens 3 mentioned in this application can also be used in other scenarios, such as the eyepiece or objective lens of a microscope, which will not be further described in this application.

[0102] It is worth mentioning that, according to another aspect of the present application, as shown in FIG8 , an embodiment of the present application further provides a method for manufacturing a transmissive achromatic flat lens, which may include the following steps:

[0103] S110: manufacturing a first CLC volume hologram element, wherein the first CLC volume hologram element comprises an alignment layer for recording lens information and a cholesteric liquid crystal layer stacked on the alignment layer, wherein the helical axis of the cholesteric liquid crystal layer is perpendicular to a device surface of the first CLC volume hologram element; and

[0104] S120: Disposing a reflective element on the reflective side of the first CLC volume hologram element to reflect the first circularly polarized light emitted from the reflective element through the curved surface of the first CLC volume hologram element to modulate the propagation direction of the first circularly polarized light, and transmitting the second circularly polarized light emitted from the reflective element and having a rotation direction opposite to that of the first circularly polarized light.

[0105] It is worth noting that in the above embodiment of the present application, as shown in FIG8 , the method for manufacturing the transmissive achromatic flat lens may further include the following steps:

[0106] S130: Disposing a leakage light eliminating component on the light-transmitting side of the first CLC volume holographic element to eliminate the first circularly polarized light leaking through the first CLC volume holographic element and transmit the second circularly polarized light passing through the first CLC volume holographic element.

[0107] Optionally, in the above embodiment of the present application, as shown in FIG8 , the method for manufacturing the transmissive achromatic flat lens may further include the following steps:

[0108] S140: Disposing a polarizing element on the light incident side of the reflective element to polarize the incident light into the first circularly polarized light for incident on the reflective element, and absorbing the second circularly polarized light reflected by the reflective element toward the light incident side.

[0109] Optionally, in the above embodiment of the present application, as shown in FIG8 , the method for manufacturing the transmissive achromatic flat lens may further include the following steps:

[0110] S150: Disposing a second CLC volume holographic element between the polarizing component and the reflective element to transmit the first circularly polarized light to propagate to the reflective element, and reflecting the second circularly polarized light from the reflective element to modulate the propagation direction of the second circularly polarized light.

[0111] It is understandable that the order of S120, S130, S140 and S150 mentioned in this application can be interchanged; for example, step S140 can be before step S120 or step S130, or step S130 can be before step S120, and this application will not go into details.

[0112] In one example of the present application, as shown in FIG9 , step S110 in the method for manufacturing the transmissive achromatic flat lens may include the following steps:

[0113] S111: coating a liquid crystal alignment material on a light-transmitting substrate;

[0114] S112: exposing the liquid crystal alignment material through a double-beam interference exposure process to form an alignment layer that records lens information in the form of an alignment direction; and

[0115] S113: coating a cholesteric liquid crystal material on the alignment layer to form a cholesteric liquid crystal layer.

[0116] It is understood that the liquid crystal molecules in the cholesteric liquid crystal material coated on the alignment layer will follow the alignment recorded in the alignment layer, thereby changing the alignment of the liquid crystal molecules point by point on the alignment layer; at the same time, the recorded lens information will be transmitted layer by layer along the thickness direction of the cholesteric liquid crystal layer to have a reflected light focal length.

[0117] It is worth mentioning that, according to another aspect of the present application, as shown in FIG10 , an embodiment of the present application further provides a method for achromatic transmission imaging, which may include the following steps:

[0118] S220: transmitting the first circularly polarized light through the anti-transmission element to propagate to the first CLC volume holographic element;

[0119] S230: The first circularly polarized light is reflected by the curved surface of the first CLC volume holographic element so as to propagate back to the anti-transmission element;

[0120] S240: reflecting the first circularly polarized light through the anti-transmission element to form a second circularly polarized light having a rotation direction opposite to that of the first circularly polarized light, so as to propagate the second circularly polarized light to the first CLC volume holographic element again; and

[0121] S250: Transmitting the second circularly polarized light through the first CLC volume hologram element to form an image.

[0122] It is worth noting that, according to the above embodiment of the present application, as shown in FIG10 , the achromatic transmission imaging method further includes the following steps before step S220:

[0123] S210: polarizing the incident light into the first circularly polarized light so as to allow the first circularly polarized light to enter the light incident surface of the reflective element.

[0124] Optionally, as shown in FIG11 , step S210 of the achromatic transmission imaging method may include the following steps:

[0125] S211: absorbing the second linearly polarized light in the incident light and transmitting the first linearly polarized light in the incident light;

[0126] S212: converting the transmitted first linearly polarized light into a first circularly polarized light for incident on the anti-transmission element, so that a portion of the first circularly polarized light passes through the anti-transmission element and is incident on the first CLC volume hologram element, and another portion of the first circularly polarized light is reflected by the anti-transmission element to form a second circularly polarized light propagating toward the light incident side; and

[0127] S213: Convert the second circularly polarized light propagating toward the incident light side into the second linearly polarized light to be absorbed.

[0128] In the above embodiment of the present application, as shown in FIG10 , the achromatic transmission imaging method may further include the steps of:

[0129] S260: Eliminating the first circularly polarized light leaking through the first CLC volume hologram element, and transmitting the second circularly polarized light passing through the first CLC volume hologram element.

[0130] Optionally, as shown in FIG12 , step S260 of the achromatic transmission imaging method may include the following steps:

[0131] S261: converting the first circularly polarized light and the second circularly polarized light transmitted through the first CLC volume hologram element into the first linearly polarized light and the second linearly polarized light respectively; and

[0132] S262: Absorbing the first linearly polarized light and transmitting the second linearly polarized light.

[0133] It is worth noting that in practical optical applications, the transmissive achromatic flat lens of this application can be rotated to any specified angle to adjust the polarization direction of the output light to a specified polarization direction. Of course, in another practical optical application, by adding quarter-wave plates on both the incident side of the polarizing component and the exit side of the leakage-light-eliminating component, both the incident and exit light can be made compatible with circularly polarized light without introducing additional optical loss.

[0134] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.

[0135] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A transmissive achromatic flat lens, characterized in that, Comprising: A first CLC volume holographic element, having an alignment layer for recording lens information and a cholesteric liquid crystal layer stacked on the alignment layer, the helical axis of the cholesteric liquid crystal layer being perpendicular to the device surface of the first CLC volume holographic element, for reflecting a first circularly polarized light to modulate the propagation direction of the first circularly polarized light and transmitting a second circularly polarized light with a helicity opposite to that of the first circularly polarized light for output; And A beam splitting element for reflecting a part of the light and transmitting another part of the light, disposed on the reflective side of the first CLC volume holographic element, for partially transmitting the incident light to form a first circularly polarized light incident on the first CLC volume holographic element and partially reflecting the first circularly polarized light reflected by the first CLC volume holographic element to form the second circularly polarized light and incident on the first CLC volume holographic element.

2. The transmissive achromatic flat lens according to claim 1, wherein, The number of the first CLC volume holographic elements is multiple, and the multiple first CLC volume holographic elements are stacked on each other.

3. The transmissive achromatic flat lens according to claim 1, wherein, The beam splitting element is a semi-transmissive and semi-reflective film attached to the first CLC volume holographic element.

4. The transmissive achromatic flat lens according to any one of claims 1 to 3, wherein, It further includes a light leakage elimination component, the light leakage elimination component being disposed on the light-transmissive side of the first CLC volume holographic element, for eliminating the first circularly polarized light leaked through the first CLC volume holographic element and transmitting the second circularly polarized light transmitted through the first CLC volume holographic element.

5. The transmissive achromatic flat lens according to claim 4, wherein, The light leakage elimination component includes a first linear polarizing element for absorbing a first linearly polarized light and transmitting a second linearly polarized light and a first phase retarder located between the first CLC volume holographic element and the first linear polarizing element, the first phase retarder being used for converting the first circularly polarized light into the first linearly polarized light and converting the second circularly polarized light into the second linearly polarized light.

6. The transmissive achromatic flat lens according to claim 5, wherein, The first linear polarizing element is a linear polarizer; the first phase retarder is a quarter-wave plate; the first linear polarizing element and the first phase retarder are sequentially stacked on the light-transmissive side of the first CLC volume holographic element.

7. The transmissive achromatic flat lens according to any one of claims 1 to 3, wherein, It further includes a polarization component, the polarization component being disposed on the light-incident side of the beam splitting element, for polarizing the incident light into the first circularly polarized light to be incident on the beam splitting element.

8. The transmissive achromatic flat lens according to claim 7, wherein, The polarization component includes a second linear polarizing element for absorbing a second linearly polarized light and transmitting a first linearly polarized light and a second phase retarder located between the second linear polarizing element and the beam splitting element, the second phase retarder being used for converting the first linearly polarized light transmitted through the second linear polarizing element into the first circularly polarized light to be incident on the beam splitting element and converting the second circularly polarized light reflected by the beam splitting element towards the light-incident side into the second linearly polarized light to be absorbed by the second linear polarizing element.

9. The transmissive achromatic flat lens according to claim 7, wherein, It further includes a second CLC volume holographic element disposed between the polarization component and the beam splitting element, for transmitting the first circularly polarized light to propagate to the beam splitting element and reflecting the second circularly polarized light from the beam splitting element to modulate the propagation direction of the second circularly polarized light.

10. An optical lens, characterized in that, Including a transmissive achromatic flat lens; the transmissive achromatic flat lens includes: A first CLC volume holographic element, having an alignment layer for recording lens information and a cholesteric liquid crystal layer stacked on the alignment layer, the helical axis of the cholesteric liquid crystal layer being perpendicular to the device surface of the first CLC volume holographic element, for reflecting a first circularly polarized light to modulate the propagation direction of the first circularly polarized light, and transmitting a second circularly polarized light having a helicity opposite to that of the first circularly polarized light for output; and A beam splitting element for reflecting a part of light and transmitting another part of light, disposed on the reflective side of the first CLC volume holographic element, for partially transmitting incident light to form a first circularly polarized light incident on the first CLC volume holographic element, and partially reflecting the first circularly polarized light reflected by the first CLC volume holographic element to form the second circularly polarized light and incident on the first CLC volume holographic element.

11. Imaging module, characterized in that, Comprising: A photosensitive component; And An optical lens, the optical lens being disposed on the photosensitive side of the photosensitive component; the optical lens includes a transmissive achromatic flat lens; the transmissive achromatic flat lens includes: A first CLC volume holographic element, having an alignment layer for recording lens information and a cholesteric liquid crystal layer stacked on the alignment layer, the helical axis of the cholesteric liquid crystal layer being perpendicular to the device surface of the first CLC volume holographic element, for reflecting a first circularly polarized light to modulate the propagation direction of the first circularly polarized light, and transmitting a second circularly polarized light having a helicity opposite to that of the first circularly polarized light for output; And A beam splitting element for reflecting a part of light and transmitting another part of light, disposed on the reflective side of the first CLC volume holographic element, for partially transmitting incident light to form a first circularly polarized light incident on the first CLC volume holographic element, and partially reflecting the first circularly polarized light reflected by the first CLC volume holographic element to form the second circularly polarized light and incident on the first CLC volume holographic element.

12. A method for manufacturing a transmissive achromatic flat lens, characterized in that, Including the steps of: Fabricating a first CLC volume holographic element, wherein the first CLC volume holographic element has an alignment layer for recording lens information and a cholesteric liquid crystal layer stacked on the alignment layer, the helical axis of the cholesteric liquid crystal layer being perpendicular to the device surface of the first CLC volume holographic element; And Disposing a beam splitting element on the reflective side of the first CLC volume holographic element to reflect the first circularly polarized light emitted from the beam splitting element through the curved surface of the first CLC volume holographic element to modulate the propagation direction of the first circularly polarized light, and transmitting the second circularly polarized light emitted from the beam splitting element and having a helicity opposite to that of the first circularly polarized light.

13. The manufacturing method of the transmissive achromatic flat lens according to claim 12, wherein, Further including the steps of: Disposing a light leakage eliminating component on the light transmissive side of the first CLC volume holographic element to eliminate the first circularly polarized light leaked through the first CLC volume holographic element, and transmitting the second circularly polarized light transmitted through the first CLC volume holographic element.

14. The manufacturing method of the transmissive achromatic flat lens according to claim 12, wherein, Further including the steps of: Disposing a polarization component on the light incident side of the beam splitting element to polarize incident light into the first circularly polarized light to be incident on the beam splitting element, and absorbing the second circularly polarized light reflected by the beam splitting element toward the light incident side.

15. The manufacturing method of the transmissive achromatic flat lens according to claim 14, wherein, Further including the steps of: A second CLC volume holographic element is disposed between the polarizing component and the anti-reflection element to transmit the first circularly polarized light to propagate to the anti-reflection element and reflect the second circularly polarized light from the anti-reflection element to modulate the propagation direction of the second circularly polarized light.

16. The manufacturing method of the transmissive achromatic flat lens according to any one of claims 12 to 15, wherein, The step of fabricating the first CLC volume holographic element includes the steps of: Coating a liquid crystal alignment material on a light-transmissive substrate; Exposing the liquid crystal alignment material through a two-beam interference exposure process to form an alignment layer that records lens information in the form of an alignment direction; And Coating a cholesteric liquid crystal material on the alignment layer to form a cholesteric liquid crystal layer.

17. A method for colorless difference transmission imaging, characterized in that, Including the steps of: Transmitting the first circularly polarized light through the anti-reflection element to propagate to the first CLC volume holographic element; Curvedly reflecting the first circularly polarized light through the first CLC volume holographic element to propagate back to the anti-reflection element; Reflecting the first circularly polarized light through the anti-reflection element to form a second circularly polarized light with a rotation direction opposite to that of the first circularly polarized light to propagate to the first CLC volume holographic element again; And Transmitting the second circularly polarized light through the first CLC volume holographic element for imaging.

18. The color difference-free transmission imaging method according to claim 17, wherein, Before the step of transmitting the first circularly polarized light through the anti-reflection element to propagate to the first CLC volume holographic element, the steps further include: Polarizing the incident light into the first circularly polarized light and injecting it from the light-incident surface of the anti-reflection element.

19. The method for achromatic transmission imaging according to claim 18, wherein, The step of polarizing the incident light into the first circularly polarized light and injecting it from the light-incident surface of the anti-reflection element includes the steps of: Absorbing the second linearly polarized light in the incident light and transmitting the first linearly polarized light in the incident light; Converting the transmitted first linearly polarized light into the first circularly polarized light and injecting it into the anti-reflection element, such that a part of the first circularly polarized light passes through the anti-reflection element and is injected into the first CLC volume holographic element, and another part of the first circularly polarized light is reflected by the anti-reflection element to form a second circularly polarized light propagating towards the light-incident side; And Converting the second circularly polarized light propagating towards the light-incident side into the second linearly polarized light to be absorbed.

20. The achromatic transmission imaging method according to any one of claims 17 to 19, wherein Further including the steps of: Eliminating the first circularly polarized light leaking through the first CLC volume holographic element and transmitting the second circularly polarized light passing through the first CLC volume holographic element.

21. The achromatic transmission imaging method according to claim 20, wherein, The step of eliminating the first circularly polarized light leaking through the first CLC volume holographic element and transmitting the second circularly polarized light passing through the first CLC volume holographic element includes the steps of: Respectively converting the first circularly polarized light and the second circularly polarized light passing through the first CLC volume holographic element into the first linearly polarized light and the second linearly polarized light; and Absorbing the first linearly polarized light and transmitting the second linearly polarized light.

Images