Transmission-type chromatic aberration-free flat lens and method and application thereof

Abstract

The invention provides a transmission-type chromatic aberration-free flat lens and a method and application thereof, which can thoroughly solve the chromatic dispersion problem and simultaneously modulate light rays in a transmission mode. The transmission-type chromatic-aberration-free flat lens comprises a first CLC body holographic element, an alignment layer for recording lens information and a cholesteric liquid crystal layer stacked on the alignment layer, the spiral axis of the cholesteric liquid crystal layer is perpendicular to the device surface of the first CLC body holographic element, and the cholesteric liquid crystal layer is used for reflecting first circularly polarized light to modulate the propagation direction of the first circularly polarized light. The rotation direction of the second circularly polarized light is opposite to that of the first circularly polarized light; the reflecting and transmitting element is used for reflecting one part of light rays and transmitting the other part of light rays, is arranged on the reflecting side of the first CLC body holographic element and is used for partially transmitting incident light to form first circularly polarized light entering the first CLC body holographic element; and the first circularly polarized light reflected by the first CLC body holographic element is partially reflected to form second circularly polarized light which enters the first CLC body holographic element.

Description

Technical Field

[0001] The present invention relates to the technical field of cholesteric liquid crystal, and particularly to a transmissive achromatic flat lens and its method and application. Background Art

[0002] Currently, existing lenses basically face the problem of broadband dispersion. For example: refractive optics has dispersion problems; the dispersion problems of diffractive optics are more serious; traditional holographic optics is extremely sensitive to both wavelength and incident angle. Although reflective optics has the characteristic of broadband achromatism and thus has no dispersion problem, it is inconvenient to use and difficult to be applied in imaging systems.

[0003] To solve the dispersion problem, existing technical solutions usually combine diffractive optical devices and refractive optical devices to utilize the complementary dispersion properties of diffractive optics and refractive optics to offset chromatic aberration to a certain extent. However, limited by factors such as material refractive index and / or Abbe number, this refractive-diffractive combination scheme is difficult to completely offset chromatic aberration and still has dispersion problems. In addition, most traditional refractive optical devices achieve a specific phase distribution by constructing a curved surface shape, but the volume and weight of such devices are usually large, resulting in a large volume and weight of the refractive-diffractive combination scheme, which is not conducive to imaging applications. Summary of the Invention

[0004] An advantage of the present application is to provide a transmissive achromatic flat lens and its method and application, which can completely solve the dispersion problem while modulating light transmissively, so as to perfectly replace the application of traditional curved lenses in optical imaging.

[0005] Another advantage of the present application is to provide a transmissive achromatic flat lens and its method and application. In one embodiment of the present invention, the transmissive achromatic flat lens can perfectly inherit the achromatic characteristic of reflective optics to completely solve the dispersion problem.

[0006] Another advantage of the present application is to provide a transmissive achromatic flat lens and its method and application. In one embodiment of the present invention, the broadband of the transmissive achromatic flat lens can cover the entire visible light, facilitating its application in white light imaging systems.

[0007] Another advantage of the present application is to provide a transmissive achromatic flat lens and its method and application. In one embodiment of the present invention, the transmissive achromatic flat lens can utilize the optical characteristics of CLC (Cholesteric liquid crystal) to achieve insensitivity to the incident light angle, with a relatively large tolerance, and both the practicability and applicability are relatively good.

[0008] Another advantage of the present application is to provide a transmissive achromatic flat lens, its method and application. Among them, in one embodiment of the present invention, the transmissive achromatic flat lens can have a relatively large aperture and strong focusing ability.

[0009] Another advantage of the present application is to provide a transmissive achromatic flat lens, its method and application. To achieve the above object, in the present invention, expensive materials or complex structures do not need to be used. Therefore, the present invention successfully and effectively provides a solution, not only providing a simple transmissive achromatic flat lens, its method and application, but also increasing the practicability and reliability of the transmissive achromatic flat lens, its method and application.

[0010] To achieve at least one of the above advantages or other advantages and purposes of the present application, the present invention provides a transmissive achromatic flat lens, including:

[0011] 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 rotation direction opposite to that of the first circularly polarized light for output; and

[0012] A beam splitting element for reflecting a part of light and transmitting another part of light, disposed on the light reflecting 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 injecting it into the first CLC volume holographic element.

[0013] According to an embodiment of the present application, the number of the first CLC volume holographic elements is multiple, and the multiple first CLC volume holographic elements are stacked on each other.

[0014] According to an embodiment of the present application, the beam splitting element is a semi-reflective and semi-transmissive film attached to the first CLC volume holographic element.

[0015] According to an embodiment of the present application, the transmissive achromatic flat lens 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.

[0016] According to an embodiment of the present application, the light leakage elimination component includes a first linear polarizing element for absorbing the first linearly polarized light and transmitting the 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 is configured to convert the first circularly polarized light into the first linearly polarized light and convert the second circularly polarized light into the second linearly polarized light.

[0017] According to an embodiment of the present application, 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-transmitting side of the first CLC volume holographic element.

[0018] According to an embodiment of the present application, the transmissive achromatic flat lens further includes a polarization component, which is disposed on the light-incident side of the anti-transmission element and is configured to polarize the incident light into the first circularly polarized light to be incident on the anti-transmission element.

[0019] According to an embodiment of the present application, the polarization component includes a second linear polarizing element for absorbing the second linearly polarized light and transmitting the first linearly polarized light, and a second phase retarder located between the second linear polarizing element and the anti-transmission element. The second phase retarder is configured to convert the first linearly polarized light transmitted through the second linear polarizing element into the first circularly polarized light to be incident on the anti-transmission element, and convert the second circularly polarized light reflected from the anti-transmission element toward the light-incident side into the second linearly polarized light to be absorbed by the second linear polarizing element.

[0020] According to an embodiment of the present application, the transmissive achromatic flat lens further includes a second CLC volume holographic element disposed between the polarization component and the anti-transmission element, which is configured to transmit the first circularly polarized light to propagate to the anti-transmission element and reflect the second circularly polarized light from the anti-transmission element to modulate the propagation direction of the second circularly polarized light.

[0021] On the other hand, according to the present application, the present application further provides an optical lens, which is characterized by including the transmissive achromatic flat lens described in any one of the above.

[0022] On the other hand, according to the present application, the present application further provides an imaging module, including:

[0023] a photosensitive component; and

[0024] the above optical lens, and the optical lens is disposed on the photosensitive side of the photosensitive component.

[0025] On the other hand, according to the present application, the present application further provides a manufacturing method of a transmissive achromatic flat lens, including the steps:

[0026] Fabricate a first CLC volume holographic element, where 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, and the helical axis of the cholesteric liquid crystal layer is perpendicular to the device surface of the first CLC volume holographic element; and

[0027] Arrange an antireflection element on the reflective side of the first CLC volume holographic element to modulate the propagation direction of the first circularly polarized light emitted from the antireflection element by reflecting it through the curved surface of the first CLC volume holographic element, and transmit the second circularly polarized light emitted from the antireflection element and having a rotation direction opposite to that of the first circularly polarized light.

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

[0029] Arrange a light leakage elimination 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 transmitted through the first CLC volume holographic element.

[0030] According to an embodiment of the present application, the method for manufacturing the transmissive achromatic flat lens further includes the step of:

[0031] Arrange a polarization component on the light-incident side of the antireflection element to polarize the incident light into the first circularly polarized light to be incident on the antireflection element and absorb the second circularly polarized light reflected by the antireflection element toward the light-incident side.

[0032] According to an embodiment of the present application, the method for manufacturing the transmissive achromatic flat lens further includes the step of:

[0033] Arrange a second CLC volume holographic element between the polarization component and the antireflection element to transmit the first circularly polarized light to propagate to the antireflection element and reflect the second circularly polarized light from the antireflection element to modulate the propagation direction of the second circularly polarized light.

[0034] According to an embodiment of the present application, the step of fabricating the first CLC volume holographic element includes the steps of:

[0035] Coat a liquid crystal alignment material on a light-transmitting substrate;

[0036] Through a two-beam interference exposure process, expose the liquid crystal alignment material to form an alignment layer that records lens information in the form of an alignment direction; and

[0037] Coat a cholesteric liquid crystal material on the alignment layer to form a cholesteric liquid crystal layer.

[0038] According to another aspect of the present application, the present application further provides a method for achromatic transmission imaging, including the steps of:

[0039] Transmit the first circularly polarized light through the anti-reflection element to propagate to the first CLC volume holographic element;

[0040] Curvedly reflect the first circularly polarized light through the first CLC volume holographic element to propagate back to the anti-reflection element;

[0041] Reflect the first circularly polarized light through the anti-reflection element to form a second circularly polarized light with the opposite sense of rotation to the first circularly polarized light to propagate to the first CLC volume holographic element again; and

[0042] Transmit the second circularly polarized light through the first CLC volume holographic element for imaging.

[0043] According to an embodiment of the present application, 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 method further includes the steps of:

[0044] Polarize the incident light into the first circularly polarized light and inject it from the incident light surface of the anti-reflection element.

[0045] According to an embodiment of the present application, the step of polarizing the incident light into the first circularly polarized light and injecting it from the incident light surface of the anti-reflection element includes the steps of:

[0046] Absorb the second linearly polarized light in the incident light and transmit the first linearly polarized light in the incident light;

[0047] Convert the transmitted first linearly polarized light into the first circularly polarized light and inject it into the anti-reflection element, so that a part of the first circularly polarized light passes through the anti-reflection element and injects 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 incident light side; and

[0048] Convert the second circularly polarized light propagating towards the incident light side into the second linearly polarized light to be absorbed.

[0049] According to an embodiment of the present application, the method for achromatic transmission imaging further includes the steps of:

[0050] Eliminate the first circularly polarized light leaking through the first CLC volume holographic element and transmit the second circularly polarized light transmitted through the first CLC volume holographic element.

[0051] According to an embodiment of the present application, the step of eliminating the first circularly polarized light leaking through the first CLC volume holographic element and transmitting the second circularly polarized light transmitted through the first CLC volume holographic element includes the steps of:

[0052] The first circularly polarized light and the second circularly polarized light passing through the first CLC volume holographic element are respectively converted into the first linearly polarized light and the second linearly polarized light; and

[0053] Absorb the first linearly polarized light and transmit the second linearly polarized light. Description of the Drawings

[0054] Figure 1 is a schematic structural diagram of a transmissive achromatic flat lens according to an embodiment of the present application;

[0055] Figure 2 shows a schematic diagram of the folded optical path of the transmissive achromatic flat lens according to the above embodiment of the present application;

[0056] Figure 3 shows an example of the first CLC volume holographic element in the transmissive achromatic flat lens according to the above embodiment of the present application;

[0057] Figure 4 shows a schematic diagram of the reflection spectrum of the first CLC volume holographic element according to the above example of the present application;

[0058] Figure 5 shows a specific example of the transmissive achromatic flat lens according to the above embodiment of the present application;

[0059] Figure 6 shows a modified example of the transmissive achromatic flat lens according to the above embodiment of the present application;

[0060] Figure 7 is a schematic block diagram of an imaging module according to an embodiment of the present application;

[0061] Figure 8 is a schematic flow diagram of a manufacturing method of a transmissive achromatic flat lens according to an embodiment of the present application;

[0062] Figure 9 shows an example of the manufacturing step of the first CLC volume holographic element in the manufacturing method of the transmissive achromatic flat lens according to the above embodiment of the present application;

[0063] Figure 10 is a schematic flow diagram of an achromatic transmission imaging method according to an embodiment of the present application;

[0064] Figure 11 shows an example of the polarization step in the achromatic transmission imaging method according to the above embodiment of the present application;

[0065] Figure 12Shows an example of the light leakage elimination step in the achromatic transmission imaging method according to the above embodiments of the present application.

[0066] Main element symbol description: 1, transmissive achromatic flat lens; 10, retroreflective element; 100, semi-transparent semi-reflective film; 101, incident light surface; 102, exit light surface; 20, first CLC volume holographic element; 21, alignment layer; 22, cholesteric liquid crystal layer; 30, light leakage elimination component; 31, first linear polarizing element; 32, first phase retarder; 40, polarization component; 41, second linear polarizing element; 42, second phase retarder; 50, second CLC volume holographic element; 2, photosensitive component; 3, optical lens.

[0067] The above main element symbol description further describes the present application in detail in conjunction with the accompanying drawings and specific embodiments. Specific embodiments

[0068] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and other obvious variations can be conceived by those skilled in the art. The basic principles defined in the following description of the present invention can be applied to other implementation schemes, deformation schemes, improvement schemes, equivalent schemes, and other technical schemes without departing from the spirit and scope of the present invention.

[0069] Those skilled in the art should understand that in the disclosure of the present invention, the orientation or positional relationship indicated by terms such as "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 construed as limitations on the present invention.

[0070] In the present invention, the term "a" in the claims and the specification should be understood as "one or more". That is, in one embodiment, the number of an element can be one, and in other embodiments, the number of the element can be multiple. Unless it is clearly indicated in the disclosure of the present invention that the number of the element is only one, the term "a" cannot be understood as unique or single, and the term "a" cannot be understood as a limitation on the number.

[0071] In the description of the present invention, it should be understood that terms such as "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through a medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0072] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions 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 a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0073] Considering that although the existing diffractive-refractive combination scheme can offset chromatic aberration to a certain extent by utilizing the complementary dispersion performance of diffractive optics and refractive optics, it is difficult to completely offset chromatic aberration due to factors such as material refractive index and / or Abbe number, and there is still a dispersion problem. Therefore, the present application creatively proposes a transmissive achromatic flat lens and its method and application, which can completely solve the dispersion problem while modulating light transmissively, so as to perfectly replace the application of traditional curved lenses in optical imaging.

[0074] Specifically, referring to the Figures 1 to 5 accompanying drawings of the present application, according to an embodiment of the present application, a transmissive achromatic flat lens 1 is provided, which may include a dichroic element 10 for reflecting a part of light and transmitting another part of light and a first CLC volume holographic element 20. The dichroic element 10 is disposed on the reflective side of the first CLC volume holographic element 20.

[0075] More specifically, as Figure 1 and Figure 2As shown, the beam splitting element 10 is configured to partially transmit incident light to form first circularly polarized light that enters the first CLC volume holographic element 20, and partially reflect the first circularly polarized light reflected by the first CLC volume holographic element 20 to form second circularly polarized light with a helicity opposite to that of the first circularly polarized light and enter the first CLC volume holographic element 20. The first CLC volume holographic element 20 has an alignment layer 21 for recording lens information and a cholesteric liquid crystal layer 22 stacked on the alignment layer 21. The helical axis of the cholesteric liquid crystal layer 22 is perpendicular to the device surface of the first CLC volume holographic element 20, and is configured to reflect the first circularly polarized light partially transmitted by the beam splitting element 10 to modulate the propagation direction of the first circularly polarized light and propagate back to the beam splitting element 10, and transmit the second circularly polarized light partially reflected by the beam splitting element 10.

[0076] Exemplarily, as Figure 1 and Figure 2 shown, the beam splitting element 10 has a light incident surface 101 and a light exit surface 102 arranged opposite to each other, and the first CLC volume holographic element 20 is located on the light exit side of the beam splitting element 10. Thus, as Figure 2 shown, the first circularly polarized light incident from the light incident surface 101 first partially passes through the beam splitting element 10 to form first circularly polarized light exiting from the light exit surface 102 and propagate to the first CLC volume holographic element 20, and then is reflected by the curved surface of the first CLC volume holographic element 20 to propagate back to the light exit surface 102 after modulating the propagation direction; then, the first circularly polarized light incident from the light exit surface 102 is partially reflected by the beam splitting element 10 to form second circularly polarized light exiting from the light exit surface 102; finally, the second circularly polarized light exiting from the light exit surface 102 propagates to the first CLC volume holographic element 20 again to pass through the first CLC volume holographic element 20. In other words, the transmissive achromatic flat lens 1 of the present application forms folded optics through the beam splitting element 10 and the first CLC volume holographic element 20, converts the reflection system into a transmission system, and retains the broadband achromatic characteristic of the reflection optics, so as to be equivalent to a transmissive flat optical device as a whole, which can not only completely solve the chromatic dispersion problem, but also modulate light in a transmissive manner, so as to perfectly replace the application of a traditional curved lens in optical imaging.

[0077] It should be noted that the CLC mentioned in this application refers to cholesteric liquid crystal (Cholesteric liquid crystal in English). As a material with strong polarization selectivity, it reflects all circularly polarized light of a specific handedness at an angle that satisfies Bragg's law and transmits all circularly polarized light of the other handedness. At the same time, the optical properties of the first CLC volume holographic element 20 mentioned in this application are determined by the alignment layer 21. Based on a specific alignment layer design and exposure, it can have a lens-like optical power and is a planar optical element capable of modulating reflected light.

[0078] In addition, since the cholesteric liquid crystal layer 22 of the first CLC volume holographic element 20 has an angular reflection bandwidth, when using the transmissive achromatic flat lens 1, the incident angle of the first circularly polarized light transmitted through the anti-reflection element 10 on the device surface of the first CLC volume holographic element 20 (i.e., the angle between the first circularly polarized light and the helical axis of the cholesteric liquid crystal layer 22) needs to be within this angular reflection bandwidth. It can be understood that the cholesteric liquid crystal layer 22 can be regarded as composed of a one-dimensional Bragg along the helical axis and a mirror surface perpendicular to the helical axis: Bragg determines the reflection center wavelength, and the mirror surface determines the reflection imaging law; the reflection imaging law of the cholesteric liquid crystal layer 22 follows that the angles formed by the incident, reflected, and mirror normal are equal, which is the same as the general Fresnel mirror reflection law; therefore, the reflection of the first CLC volume holographic element 20 in this application within its angular reflection bandwidth is wavelength-independent; that is to say, the reflection of the first CLC volume holographic element 20 in this application is achromatic.

[0079] It can be understood that, different from traditional volume holography, the first CLC volume holographic element 20 in this application can record lens information on the alignment layer 21 by means of two-beam interference, making the reflection surface of the cholesteric liquid crystal layer 22 change from a traditional plane to a curved surface, that is, its reflection surface is not always perpendicular to the helical axis everywhere, but does not affect the basic law of reflection imaging, which is equivalent to forming a reflection lens for reflecting the first circularly polarized light emitted from the light exit surface 102 in a curved surface.

[0080] Exemplarily, such as Figure 2 and Figure 5As shown in the figure, taking the right-handed circularly polarized light (hereinafter referred to as RCP) as the first circularly polarized light and the left-handed circularly polarized light (hereinafter referred to as LCP) as the second circularly polarized light as an example: a corresponding chiral material is doped in the cholesteric liquid crystal layer 22 of the first CLC volume holographic element 20, that is, the cholesteric liquid crystal layer 22 is configured to reflect RCP and transmit LCP. In this way, the RCP incident from the incident light surface 101 remains RCP after passing through the anti-reflection and transmission element 10 and exits from the exit light surface 102 and propagates to the first CLC volume holographic element 20; then, the RCP is reflected by the curved surface of the first CLC volume holographic element 20 and remains RCP after modulating the propagation direction, and propagates back to the exit light surface 102; after that, the RCP incident from the exit light surface 102 is reflected by the anti-reflection and transmission element 10 to change the polarization direction and form LCP exiting from the exit light surface 102; finally, the LCP exiting from the exit light surface 102 propagates to the first CLC volume holographic element 20 again and remains LCP after passing through the first CLC volume holographic element 20. It can be understood that in other examples of the present application, the first circularly polarized light may also be the left-handed circularly polarized light LCP; correspondingly, the second circularly polarized light is implemented as the right-handed circularly polarized light RCP, which will not be elaborated in the present application.

[0081] It should be noted that the first CLC volume holographic element 20 of the present application maintains the reflection characteristics of CLC, that is, optical rotation reflection and band reflection; thus, multilayer stacking can also expand the bandwidth; at the same time, the first CLC volume holographic element 20 of the present application also retains the same tolerance for the incident angle, which are the great differences between the first CLC volume holographic element 20 of the present application and traditional volume holographic devices. However, the first CLC volume holographic element 20 of the present application also inherits the advantages of traditional volume holography: such as it can record information of a large-aperture lens to achieve large focusing or diverging ability. It can be understood that the tolerance for the incident angle comes from the optical properties of the cholesteric liquid crystal itself. As long as the cholesteric liquid crystal layer 22 is thick enough, it will not be too sensitive to the incident angle.

[0082] However, although the cholesteric liquid crystal layer 22 in the first CLC volume holographic element 20 exhibits band-like reflection, a cholesteric liquid crystal layer 22 can only reflect a band with a theoretical width of dozens of nanometers. For example, taking the light with a reflection center wavelength of 550 nanometers as an example: the pitch of a cholesteric liquid crystal layer 22 is approximately 550 / 1.5 = 360 nanometers. If the refractive index difference Δn = 0.2, the reflection band is 0.2×360 = 72 nanometers, which can roughly cover one color of the display.

[0083] Therefore, in order to cover the visible light band from 400 nanometers to 700 nanometers, such as Figure 3As shown, the number of the first CLC volume holographic elements 20 in the transmissive achromatic flat lens 1 of the present application can be multiple, and a plurality of the first CLC volume holographic elements 20 are stacked on top of each other. For example, the doping concentrations of the chiral materials in the cholesteric liquid crystal layers 22 of the plurality of the first CLC volume holographic elements 20 are different from each other to expand the reflection bandwidth, so that the optical paths of various colors completely coincide, completely eliminating chromatic aberration and thoroughly solving the dispersion problem. It can be understood that since the 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 pitch of the cholesteric liquid crystal, and the corresponding reflection wavelength is also smaller; therefore, as Figure 4 shown, the transmissive achromatic flat lens 1 of the present application can expand the reflection bandwidth through cholesteric liquid crystal layers 22 with different doping concentrations of chiral materials so as to cover the entire visible light band from 400 nanometers to 700 nanometers.

[0084] In addition, although the first CLC volume holographic element 20 of the present application can reflect the vast majority of the first circularly polarized light back to the anti-transmissive element 10, there is still a small amount of the first circularly polarized light that will pass through the first CLC volume holographic element 20 to form reflected light leakage, which affects the imaging quality. Therefore, as Figure 2 and Figure 5 shown, in order to eliminate the interference of the 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 holographic element 20 and is used to eliminate the first circularly polarized light leaked through the first CLC volume holographic element 20 and transmit the second circularly polarized light transmitted through the first CLC volume holographic element 20 as the outgoing light.

[0085] Optionally, as Figure 5As shown, the light leakage elimination component 30 includes a first linear polarizing element 31 for absorbing the first linearly polarized light and transmitting the second linearly polarized light, and a first phase retarder 32 located between the first CLC volume holographic element 20 and the first linear polarizing element 31. The first phase retarder 32 is used to convert the first circularly polarized light into the first linearly polarized light and convert the second circularly polarized light into the second linearly polarized light. In this way, the first circularly polarized light leaked through the first CLC volume holographic element 20 first passes through the first phase retarder 32 to be converted into the first linearly polarized light, and then passes through the first linear polarizing element 31 to be absorbed, avoiding interference of the leaked first circularly polarized light on the imaging quality; while the second circularly polarized light transmitted through the first CLC volume holographic element 20 is converted into the second linearly polarized light when passing through the first phase retarder 32, and then passes through the first linear polarizing element 31 without loss as the outgoing light, so that the second circularly polarized light transmitted through the first CLC volume holographic element 20 is not affected. It can be understood that the polarization direction of the second linearly polarized light mentioned in this application is perpendicular to the polarization direction of the first linearly polarized light; for example, the first linearly polarized light can be implemented as one of P polarized light and S polarized light; correspondingly, the second linearly polarized light is implemented as the other of P polarized light and S polarized light.

[0086] Exemplarily, the first linear polarizing element 31 can be but is not limited to being implemented as a linear polarizer, and the first phase retarder 32 can be but is not limited to being implemented as a quarter-wave plate.

[0087] Optionally, as Figure 1 and Figure 2 shown, the first phase retarder 32 and the first linear polarizing element 31 are sequentially stacked on the light-transmitting side of the first CLC volume holographic element 20 to protect the light-transmitting surface of the first CLC volume holographic element 20.

[0088] According to the above embodiments of the present application, as Figure 2 and Figure 5 shown, the transmissive achromatic flat lens 1 can further include a polarization component 40, which is disposed on the incident light side of the anti-transmission element 10 and is used to polarize the incident light into the first circularly polarized light to enter the anti-transmission element 10 from the incident light surface 101. It can be understood that in the application environment of the transmissive achromatic flat lens 1 of the present application, the incident light is usually white light rather than the first circularly polarized light, and the polarization component 40 of the present application can polarize the incident light into the first circularly polarized light to ensure that the light propagates along the designed folded optical path.

[0089] It should be noted that while a part of the first circularly polarized light polarized by the polarizing component 40 passes through the anti-reflection element 10 and propagates to the first CLC volume holographic element 20, another part will be reflected by the anti-reflection element 10 or other interfaces to form a second circularly polarized light that propagates back to the polarizing component 40 and is likely to be reflected back by the polarizing component 40 into the folding optical path to form stray light. To solve this problem, as Figure 2 and Figure 5 shown, the polarizing component 40 of the present application may include a second linear polarizing element 41 for absorbing the second linearly polarized light and transmitting the first linearly polarized light, and a second phase retarder 42 located between the second linear polarizing element 41 and the anti-reflection element 10. The second phase retarder 42 is configured to convert the first linearly polarized light transmitted through the second linear polarizing element 41 into the first circularly polarized light and inject it into the anti-reflection element 10, and convert the second circularly polarized light reflected by the anti-reflection element 10 toward the light incident side into the second linearly polarized light to be absorbed by the second linear polarizing element 41.

[0090] In this way, as Figure 5 shown, the second linearly polarized light in the incident light will be absorbed by the second linear polarizing element 41, while the first linearly polarized light in the incident light will pass through the second linear polarizing element 41 and be converted into the first circularly polarized light via the second phase retarder 42 and propagate to the anti-reflection element 10; a part of the first circularly polarized light passes through the anti-reflection element 10 and propagates to the first CLC volume holographic element 20 for folded optical imaging; at the same time, another part of the first circularly polarized light will be reflected by the anti-reflection element 10 to form a second circularly polarized light and propagate back to the second phase retarder 42; finally, the second circularly polarized light propagating back to the second phase retarder 42 will be converted into the first linearly polarized light and absorbed by the second linear polarizing element 41, eliminating stray light.

[0091] Optionally, as Figure 1 and Figure 2 shown, the second linear polarizing element 41 and the second phase retarder 42 in the polarizing component 40 are sequentially stacked on the light incident surface 101 of the anti-reflection element 10 to protect the anti-reflection element 10.

[0092] Preferably, as Figure 1 shown, the polarizing component 40, the anti-reflection element 10, the first CLC volume holographic element 20, and the light leakage elimination component 30 are assembled into an integrated device, that is, implemented as a transmissive flat imaging optical device as a whole, which is more convenient to use in optical imaging than a traditional curved lens.

[0093] In a specific example of the present application, as Figure 5As shown, in the transmissive achromatic flat lens 1 of the present application, the beam splitter element 10 can be implemented as a semi-transmissive semi-reflective film 100 attached to the first CLC volume holographic element 20. In this way, although a part of the light in the RCP incident from the incident light surface 101 will be reflected by the semi-transmissive semi-reflective film 100 and lost, another part of the light in the RCP will still pass through the semi-transmissive semi-reflective film 100 and propagate to the first CLC volume holographic element 20; then, the RCP is reflected by the curved surface of the first CLC volume holographic element 20 and remains RCP after modulating the propagation direction, and propagates back to the exit light surface 102 of the semi-transmissive semi-reflective film 100; after that, a part of the light in the RCP incident from the exit light surface 102 will be reflected by the semi-transmissive semi-reflective film 100 to change the polarization direction and form an LCP emitted from the exit light surface 102; at the same time, another part of the light in the RCP incident from the exit light surface 102 will pass through the semi-transmissive semi-reflective film 100 and be lost; finally, the LCP emitted from the exit light surface 102 propagates to the first CLC volume holographic element 20 again and remains LCP after passing through the first CLC volume holographic element 20.

[0094] It should be noted that, in a variant example of the present application, as Figure 6 shown, the transmissive achromatic flat lens 1 of the present application may further include a second CLC volume holographic element 50, which is disposed between the polarizing component 40 and the beam splitter element 10, and is used to transmit the first circularly polarized light to propagate to the beam splitter element 10 and reflect the second circularly polarized light from the beam splitter element 10 to modulate the propagation direction of the second circularly polarized light. In this way, in addition to using the first circularly polarized light transmitted through the beam splitter element 10 for modulation imaging, the transmissive achromatic flat lens 1 of the present application can also additionally use the second circularly polarized light reflected by the beam splitter element 10 for modulation imaging, so as to improve the light energy utilization rate.

[0095] Preferably, the polarizing component 40, the second CLC volume holographic element 50, the beam splitter element 10, the first CLC volume holographic element 20, and the light leakage elimination component 30 are sequentially stacked and bonded to form an integral device, that is, integrally implemented as a transmissive flat imaging optical device, which is more convenient to use in optical imaging than a traditional curved lens. In particular, in this variant example of the present application, the polarizing component 40 and the light leakage elimination component 30 may have the same structure, so that their functions can be interchanged, ensuring that both sides of the transmissive achromatic flat lens 1 can be used as the incident light side, reducing its usage limitations.

[0096] According to another aspect of the present application, as Figure 7As shown in the figure, 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. The optical lens 3 is located on the photosensitive side of the photosensitive component 2, so as to use the transmissive achromatic flat lens 1 to replace the traditional lens and achieve high-quality and clean white light imaging.

[0097] It should be noted that the optical lens 3 mentioned in the present application may only include the transmissive achromatic flat lens 1, or may be composed of a combination of the transmissive achromatic flat lens 1 and a traditional lens. In addition, the optical lens 3 mentioned in the present application can be applied not only in the imaging module for imaging modulation, but also in other scenarios such as the eyepiece or objective lens in a microscope, etc. The present application will not elaborate on this.

[0098] It is worth mentioning that according to another aspect of the present application, as Figure 8 shown in the figure, an embodiment of the present application further provides a manufacturing method of a transmissive achromatic flat lens, which may include the steps:

[0099] S110: Fabricate a first CLC volume holographic element, where 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, and the helical axis of the cholesteric liquid crystal layer is perpendicular to the device surface of the first CLC volume holographic element; and

[0100] S120: Set an antireflection element on the reflective side of the first CLC volume holographic element to modulate the propagation direction of the first circularly polarized light emitted from the antireflection element by reflecting it through the curved surface of the first CLC volume holographic element, and transmit the second circularly polarized light emitted from the antireflection element and having a rotation direction opposite to that of the first circularly polarized light.

[0101] It should be noted that in the above embodiment of the present application, as Figure 8 shown in the figure, the manufacturing method of the transmissive achromatic flat lens may further include the steps:

[0102] S130: Set a light leakage elimination 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 transmitted through the first CLC volume holographic element.

[0103] Optionally, in the above embodiment of the present application, as Figure 8 shown in the figure, the manufacturing method of the transmissive achromatic flat lens may further include the steps:

[0104] S140: Set a polarization component on the incident light side of the antireflection element to polarize the incident light into the first circularly polarized light to be incident into the antireflection element and absorb the second circularly polarized light reflected by the antireflection element toward the incident light side.

[0105] Optionally, in the above embodiments of the present application, as Figure 8 shown, the manufacturing method of the transmissive achromatic flat lens may further include the steps of:

[0106] S150: Set the second CLC volume holographic element 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.

[0107] It can be understood that the sequence order among S120, S130, S140, and S150 mentioned in the present 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 the present application will not elaborate on this.

[0108] In an example of the present application, as Figure 9 shown, step S110 in the manufacturing method of the transmissive achromatic flat lens may include the steps of:

[0109] S111: Coat a liquid crystal alignment material on a light-transmitting substrate;

[0110] S112: Through a two-beam interference exposure process, expose the liquid crystal alignment material to form an alignment layer that records lens information in the form of an alignment direction; and

[0111] S113: Coat a cholesteric liquid crystal material on the alignment layer to form a cholesteric liquid crystal layer.

[0112] It can be 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 to change 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 power.

[0113] It is worth mentioning that according to another aspect of the present application, as Figure 10 shown, an embodiment of the present application further provides an achromatic transmission imaging method, which may include the steps of:

[0114] S220: Through the anti-reflection element, transmit the first circularly polarized light to propagate to the first CLC volume holographic element;

[0115] S230: Through the first CLC volume holographic element, reflect the first circularly polarized light in a curved surface to propagate back to the anti-reflection element;

[0116] S240: Reflect the first circularly polarized light through the beam splitter to form a second circularly polarized light with a rotation direction opposite to that of the first circularly polarized light, and then propagate the second circularly polarized light back to the first CLC volume holographic element; and

[0117] S250: Transmit the second circularly polarized light through the first CLC volume holographic element for imaging.

[0118] It should be noted that, according to the above embodiments of the present application, as Figure 10 shown, before step S220 of the achromatic transmission imaging method, the method further includes the step of:

[0119] S210: Polarize the incident light into the first circularly polarized light and then inject the first circularly polarized light into the light incident surface of the beam splitter.

[0120] Optionally, as Figure 11 shown, step S210 of the achromatic transmission imaging method may include the steps of:

[0121] S211: Absorb the second linearly polarized light in the incident light and transmit the first linearly polarized light in the incident light;

[0122] S212: Convert the transmitted first linearly polarized light into the first circularly polarized light and then inject the first circularly polarized light into the beam splitter, so that a part of the first circularly polarized light passes through the beam splitter and is injected into the first CLC volume holographic element, and another part of the first circularly polarized light is reflected by the beam splitter to form a second circularly polarized light propagating towards the light incident side; and

[0123] S213: Convert the second circularly polarized light propagating towards the light incident side into the second linearly polarized light and then absorb the second linearly polarized light.

[0124] In the above embodiments of the present application, as Figure 10 shown, the achromatic transmission imaging method may further include the step of:

[0125] S260: Eliminate the first circularly polarized light leaking through the first CLC volume holographic element and transmit the second circularly polarized light transmitted through the first CLC volume holographic element.

[0126] Optionally, as Figure 12 shown, step S260 of the achromatic transmission imaging method may include the steps of:

[0127] S261: Respectively convert the first circularly polarized light and the second circularly polarized light transmitted through the first CLC volume holographic element into the first linearly polarized light and the second linearly polarized light; and

[0128] S262: Absorb the first linearly polarized light and transmit the second linearly polarized light.

[0129] It should be noted that in the actual optical application of the transmissive achromatic flat lens of the present application, the light leakage elimination component can be rotated to any specified angle so that the polarization direction of the emitted light presents a specified polarization direction. Of course, in another actual optical application, a quarter-wave plate can also be added on the incident side of the polarization component and on the output side of the light leakage elimination component to make the incident and emitted light compatible with circularly polarized light without introducing additional optical losses.

[0130] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0131] The above embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

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 outgoing; And A beam splitting and transmitting element for reflecting a part of light and transmitting another part of light, which is disposed on the light reflecting 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.

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, characterized in that, The beam splitting and transmitting 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, characterized in that, It further includes a light leakage eliminating component, which is disposed on the light transmitting 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, characterized in that, The light leakage eliminating 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, characterized in that, 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 stacked on the light transmitting side of the first CLC volume holographic element in sequence.

7. The transmissive achromatic flat lens according to any one of claims 1 to 3, characterized in that, It further includes a polarization component, which is disposed on the light incident side of the beam splitting and transmitting element, for polarizing incident light into the first circularly polarized light to be incident on the beam splitting and transmitting 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 and transmitting 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 and transmitting element, and converting the second circularly polarized light reflected by the beam splitting and transmitting 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 and transmitting element, for transmitting the first circularly polarized light to propagate to the beam splitting and transmitting element, and reflecting the second circularly polarized light from the beam splitting and transmitting element to modulate the propagation direction of the second circularly polarized light.

10. Optical lens, characterized in that, Comprising the transmissive achromatic flat lens according to any one of claims 1 to 9.

11. Imaging module, characterized in that, Comprising: A photosensitive component; And The optical lens according to claim 10, the optical lens being disposed on the photosensitive side of the photosensitive component.

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, and the helical axis of the cholesteric liquid crystal layer is perpendicular to the device surface of the first CLC volume holographic element; And Providing an antireflection element on the reflective side of the first CLC volume holographic element to modulate the propagation direction of the first circularly polarized light emitted from the antireflection element by reflecting it through the curved surface of the first CLC volume holographic element, and transmitting the second circularly polarized light emitted from the antireflection 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, characterized in that, Further including the steps of: Providing a light leakage elimination 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 transmitted through the first CLC volume holographic element.

14. The manufacturing method of the transmissive achromatic flat lens according to claim 12, characterized in that, Further including the steps of: Providing a polarization component on the light-incident side of the antireflection element to polarize the incident light into the first circularly polarized light and inject it into the antireflection element, and absorb the second circularly polarized light reflected from the antireflection element toward the light-incident side.

15. The manufacturing method of the transmissive achromatic flat lens according to claim 14, characterized in that, Further including the steps of: Providing a second CLC volume holographic element between the polarization component and the antireflection element to transmit the first circularly polarized light to propagate to the antireflection element and reflect the second circularly polarized light from the antireflection 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, characterized in that, The step of fabricating the first CLC volume holographic element includes the steps of: Coating a liquid crystal alignment material on a light-transmitting substrate; Exposing the liquid crystal alignment material through a two-beam interference exposure process to form an alignment layer recording 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. Colorless difference transmission imaging method, characterized in that, Including the steps of: Transmitting the first circularly polarized light through the antireflection 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 antireflection element; Reflecting the first circularly polarized light through the antireflection element to form a second circularly polarized light having a helicity opposite to that of the first circularly polarized light and propagating 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 antireflection element to propagate to the first CLC volume holographic element, further including the steps of: Polarizing the incident light into the first circularly polarized light and injecting it from the light-incident surface of the antireflection element.

19. The color difference-free transmission imaging method 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 antireflection 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 antireflection element, such that a part of the first circularly polarized light passes through the antireflection element and injects into the first CLC volume holographic element, and another part of the first circularly polarized light is reflected by the antireflection element to form a second circularly polarized light propagating toward the light-incident side; And Converting the second circularly polarized light propagating toward 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, characterized in that, Further including the steps of: 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.

21. The color difference-free transmission imaging method according to claim 20, characterized in that, 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: Converting the first circularly polarized light and the second circularly polarized light passing through the first CLC volume holographic element into first linearly polarized light and second linearly polarized light respectively; and Absorbing the first linearly polarized light and transmitting the second linearly polarized light.

Images