Exposure processing system and exposure processing method

Abstract

The invention discloses an exposure processing system and an exposure processing method, and the system comprises a vector metasurface template which is used for decomposing incident linearly polarized light into left-hand circularly polarized light and right-hand circularly polarized light, and can independently adjust the phase of the left-hand circularly polarized light and the phase of the right-hand circularly polarized light, the left-hand circularly polarized light and the right-hand circularly polarized light respectively have required phases; and the projection amplification unit is used for performing projection amplification processing on the left-handed circularly polarized light and the right-handed circularly polarized light emitted from the vector metasurface template, and enabling the left-handed circularly polarized light and the right-handed circularly polarized light which are subjected to the projection amplification processing to generate interference on an exposure surface and form a vector exposure field. By means of the formed large-size vector exposure field, single-time exposure forming of the large-size planar liquid crystal optical device can be achieved, the processing efficiency of exposure processing is improved, and the large-size vector exposure device has the advantages of being high in phase resolution and large in exposure at the same time and can be well suitable for processing of large-scale and large-diameter planar liquid crystal optical devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical device processing, and in particular relates to an exposure processing system and an exposure processing method. Background Art

[0002] Increasing the aperture of an optical system is currently the main means of improving the long-distance imaging resolution of an optical system. However, under the framework of the classical law of refraction and reflection, the volume and weight of a large-aperture optical system will increase exponentially with the aperture size. In comparison, planar liquid crystal optical devices have the advantages of being lightweight, highly efficient, low-cost, and capable of large-area preparation, giving them a wider range of application prospects in this field.

[0003] At present, the exposure processing of planar liquid crystal optical devices usually adopts the processing methods of area array DMD exposure and laser direct writing. With area array DMD exposure, complex exposure field distribution can be realized as needed, but limited by the size of the DMD unit itself, its resolution of phase regulation is low. With laser direct writing, complex exposure can also be realized as needed, and the phase resolution is high, but its processing speed is slow, making it difficult to meet the processing needs of large-scale and large-aperture planar liquid crystal optical devices. Summary of the invention

[0004] The purpose of the present invention is to provide an exposure processing system and an exposure processing method to solve the problem that the existing processing and molding methods have low phase resolution and slow processing speed, which makes it difficult to meet the processing needs of large-volume and large-aperture flat liquid crystal optical devices.

[0005] The present invention is achieved through the following technical solutions:

[0006] Exposure processing system, including:

[0007] A vector metasurface template, wherein the vector metasurface template is used to decompose incident linearly polarized light into left-handed circularly polarized light and right-handed circularly polarized light, and can independently adjust the phases of the left-handed circularly polarized light and the right-handed circularly polarized light, so that the left-handed circularly polarized light and the right-handed circularly polarized light have desired phases, respectively;

[0008] A projection magnification unit is used to perform projection magnification processing on the left-handed circularly polarized light and the right-handed circularly polarized light emitted from the vector metasurface template, and enable the left-handed circularly polarized light and the right-handed circularly polarized light after the projection magnification processing to interfere on the exposure surface and form a vector exposure field.

[0009] In some embodiments, the vector metasurface template adopts a composite phase design so that the vector metasurface template can independently adjust the phases of left-handed circularly polarized light and right-handed circularly polarized light.

[0010] In some embodiments, the exposure processing system further includes:

[0011] Laser light source;

[0012] A laser processing unit, the laser processing unit is used to pre-process the light beam emitted by the laser light source;

[0013] The polarization processing unit is used to process the incident laser beam into linearly polarized light.

[0014] In some embodiments, the laser processing unit includes a spatial filtering unit, a beam expansion unit, a pointing stabilization unit, and a shaping unit.

[0015] In some embodiments, the polarization processing unit includes a polarizer and a half-wave plate sequentially arranged along the optical path.

[0016] In some embodiments, a light path folding unit is also included, and the light path folding unit is used to change the direction of the light path.

[0017] On the other hand, the present invention also provides an exposure processing method, which uses the above-mentioned exposure processing system to perform exposure processing.

[0018] On the other hand, the present invention also provides an exposure processing method, comprising:

[0019] The incident linearly polarized light is decomposed into left-handed circularly polarized light and right-handed circularly polarized light by using the vector metasurface template, and the phases of the left-handed circularly polarized light and the right-handed circularly polarized light are adjusted to the required phases respectively;

[0020] The left-handed circularly polarized light and the right-handed circularly polarized light emitted from the vector metasurface template are projected and magnified, and the left-handed circularly polarized light and the right-handed circularly polarized light after the projection and magnification process interfere with each other on the exposure surface to form a vector exposure field, and the planar liquid crystal optical device set at the exposure surface is exposed through the formed vector exposure field.

[0021] In some embodiments, the exposure processing method further includes the step of processing the light emitted by the laser light source into linearly polarized light.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] The present invention adopts a vector metasurface template to independently control the phase of left-handed and right-handed circularly polarized light, respectively adjusts the left-handed and right-handed circularly polarized light to the phase required for forming a vector exposure field, and adopts a projection magnification unit to respectively amplify the left-handed and right-handed circularly polarized light, so that the amplified left-handed and right-handed circularly polarized light can interfere on the exposure surface to form a large-size vector exposure field required for exposure processing. The formed large-size vector exposure field can realize single exposure molding of large-size planar liquid crystal optical devices, thereby improving the processing efficiency of the exposure processing, making it have the characteristics of high phase resolution and large-size exposure at the same time, and can be well applied to the processing of large-volume and large-aperture planar liquid crystal optical devices.

[0024] The present invention utilizes the characteristic of the vector metasurface template that can independently control the phase. While ensuring high phase resolution, it can conveniently achieve better phase control resolution through the high-precision design of the vector metasurface template, thereby improving the exposure processing quality of the system.

[0025] Since the present invention can realize single exposure molding of the entire exposure surface, compared with the existing processing and molding methods, since multiple exposures are not required, the requirements for alignment accuracy in the processing operation can be reduced, making the processing operation simpler; and, by adjusting the projection magnification unit, one-time exposure molding of the exposure surface of any size can be realized according to the exposure processing requirements of the flat liquid crystal optical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Schematic diagram of the structure of the exposure processing system in an embodiment of the present invention.

[0028] Icons: 1. Laser light source; 2. Spatial filtering unit; 3. Beam expansion unit; 4. Pointing stabilization unit; 5. Shaping unit; 6. Polarizer; 7. First reflector; 8. Half-wave plate; 9. Second reflector; 10. Vector metasurface template; 11. Projection magnification unit; 12. Exposure surface. DETAILED DESCRIPTION

[0029] In the exposure processing of planar liquid crystal optical devices, polarized exposure of the liquid crystal orientation layer is required. Although the existing planar array DMD exposure and laser direct writing processing methods can achieve complex exposure field distribution, there are problems of low control phase resolution and slow processing speed for the processing of large-size planar liquid crystal optical devices. It is not suitable for the processing of large-volume and large-aperture planar liquid crystal optical devices.

[0030] The exposure processing system of the present invention adopts a vector metasurface template to independently regulate the phase of left-handed and right-handed circularly polarized light, respectively adjusts the left-handed and right-handed circularly polarized light to the phase required for forming a vector exposure field, and then respectively amplifies the left-handed and right-handed circularly polarized light through a projection magnification unit, so that the projected and amplified left-handed and right-handed circularly polarized light can interfere on the exposure surface to form a large-size vector exposure field required for exposure processing, thereby realizing single-shot exposure molding of large-size planar liquid crystal optical devices, which well solves the problems of low phase resolution and slow processing speed of existing processing methods.

[0031] In some embodiments of the present invention, referring to Figure 1 , the exposure processing system includes:

[0032] A vector metasurface template 10, the vector metasurface template 10 is used to decompose incident linearly polarized light into left-handed circularly polarized light and right-handed circularly polarized light, and can independently adjust the phases of the left-handed circularly polarized light and the right-handed circularly polarized light, so that the left-handed circularly polarized light and the right-handed circularly polarized light have desired phases, respectively;

[0033] The projection magnification unit 11 is used to perform projection magnification processing on the left-handed circularly polarized light and the right-handed circularly polarized light emitted from the vector metasurface template, and make the left-handed circularly polarized light and the right-handed circularly polarized light after the projection magnification processing interfere on the exposure surface and form a vector exposure field.

[0034] The vector metasurface template adopts a composite phase metasurface, which can achieve arbitrary and independent control of left- and right-handed circularly polarized light wavefronts by utilizing the different correlations between transmission phase and geometric phase in spin, frequency and material.

[0035] Transmission phase refers to the phase delay of a light beam during its propagation, which can be expressed as β = (2π / λ0)nd, where n and d are the refractive index of the material and the propagation distance, respectively. Therefore, the transmission phase is usually independent of the polarization or spin state, but is related to the frequency (or wavelength) of the incident light and the refractive index of the material. Since the structural thickness of the metasurface is the same, the transmission phase needs to be adjusted by changing the equivalent refractive index (i.e., changing the size of the subwavelength structure).

[0036] The geometric phase, also known as the Pancharatnam-Berry phase, originates from the change of the photon's internal angular momentum during the adiabatic process, and can also be regarded as the product of the interaction between the photon's spin angular momentum and the orbital angular momentum (referred to as the photon spin-orbit interaction). The geometric phase is only related to the incident light polarization and the handedness of the structure, but has nothing to do with the incident light frequency and the material. It is just the opposite of the characteristics of the transmission phase and can be expressed as α = -2σθ, where σ = ±1 represents the handedness of the incident circularly polarized light, and θ is the rotation angle of the structure.

[0037] Composite phase metasurface is a metasurface that introduces transmission phase and geometric phase into the same metasurface, that is, simultaneously changes the size and rotation direction of the subwavelength structure.

[0038] Assuming that the amplitude of the anisotropic structure is 1 and the phase delay introduced along its fast and slow axes is β±δ / 2, the corresponding complex amplitude can be expressed as tu=exp(iβ-iδ / 2) and tv=exp(iβ+iδ / 2).

[0039] When circularly polarized light [1, -iσ]T is incident, the corresponding output light field is:

[0040]

[0041] In it, it is assumed that the anisotropic structure corresponds to the u-v coordinate system, the entire metasurface corresponds to the x-y coordinate system, and θ is the angle between the two coordinate systems, that is, the rotation angle of the structure.

[0042] It can be obtained from the corresponding outgoing light field that the orthogonal polarization component carries both the transmission phase β and the geometric phase -2σθ, thereby obtaining the composite phase β-2σθ, which realizes the independent control of the phase of left- and right-handed circularly polarized light.

[0043] Based on the property that the vector metasurface template can assign the required phases to left- and right-handed circularly polarized light respectively, the required phases of left- and right-handed circularly polarized light can be calculated through the requirements of exposure processing, and then the corresponding vector metasurface template can be constructed according to the arrangement of metaatoms and the required phases, so that the vector metasurface template in the system can provide the required phases for left- and right-handed circularly polarized light, that is, realize the function of assigning phases to left- and right-handed circularly polarized light on demand.

[0044] The left-handed circularly polarized light and the right-handed circularly polarized light with the required phase provided by the vector metasurface template respectively form vector light fields, and then the vector light fields generated by the left-handed circularly polarized light and the right-handed circularly polarized light are projected and amplified by a projection amplification unit.

[0045] Here, the projection magnification unit magnifies the vector light field, and the magnified vector light field interferes on the exposure surface, so that a large-sized vector exposure field can be formed on the exposure surface. At the same time, because the vector metasurface template gives different phases to left-handed and right-handed circularly polarized light, and the propagation conditions of left-handed and right-handed circularly polarized light are also different, different magnification effects can be obtained when the left-handed and right-handed circularly polarized light are magnified by the projection magnification unit.

[0046] The vector exposure field formed by left-handed circularly polarized light and right-handed circularly polarized light on the exposure surface is an exposure field in which the linear polarization angle of light at each position is distributed as required. During exposure, this vector exposure field does not transmit information through the intensity of light, but rather through the linear polarization angle of light, thereby enabling it to realize the exposure molding of the liquid crystal orientation layer of liquid crystal planar optical devices.

[0047] The projection magnification unit here may adopt a lens group, for example, an optical path unit formed by a combination of one or more convex / concave lenses.

[0048] Reference Figure 1 After being processed by the vector metasurface template, two vector light fields with different phases are obtained, as shown by the two different colors of outgoing light rays in the figure. Then the two vector light fields are amplified separately by the projection amplification unit. Finally, the two amplified vector light fields interfere at the position of the exposure surface 12 to form the required vector exposure field.

[0049] In some embodiments, the exposure processing system further includes a unit for generating the desired linearly polarized light, including:

[0050] Laser light source 1;

[0051] A laser processing unit, which is used to perform pre-processing such as stabilizing the pointing direction, collimating, and expanding the beam emitted by the laser light source;

[0052] and a polarization processing unit, which is used to process the incident laser beam into linearly polarized light.

[0053] In some embodiments, reference Figure 1 The laser processing unit includes a spatial filter unit 2, a beam expansion unit 3 and a shaping unit 5 which are sequentially arranged along the optical path. The spatial filter unit is used to filter the light emitted by the laser light source, the beam expansion unit is used to change the diameter of the processed laser beam, and the shaping unit is used to shape the laser beam into a desired beam. The spatial filter unit, the beam expansion unit and the shaping unit can all use existing optical processing devices.

[0054] The laser processing unit may further include a pointing stabilization unit 4, which is disposed between the beam expansion unit 3 and the shaping unit 5. The pointing stabilization unit 4 may adopt an existing laser beam pointing stabilization system to perform pointing stabilization processing on the laser beam, thereby ensuring the accuracy and consistency of the lithography pattern and improving the lithography quality.

[0055] In some embodiments, reference Figure 1 The polarization processing unit performs polarization processing on the light beam obtained after filtering, beam expansion and shaping. Specifically, the polarization processing unit can use a polarizer 6 and a half-wave plate 8 arranged in sequence along the light path.

[0056] In some embodiments, the exposure processing system further includes an optical path folding unit, which is used to change the direction of the optical path. Figure 1 The optical path folding unit may adopt a first reflector 7 and a second reflector 9, wherein the first reflector is used to transmit the light emitted from the polarizer to the half-wave plate, and the second reflector is used to transmit the light emitted from the half-wave plate to the vector metasurface template, and the direction of the light incident on the first reflector is opposite to the direction of the light emitted from the second reflector, thereby changing the direction of the optical path as needed.

[0057] Of course, the optical path folding unit can be implemented by using other forms of optical path units, such as one or more reflectors.

[0058] Obviously, the present invention utilizes the characteristic of the vector metasurface template that can independently control the phase. While ensuring high phase resolution, it can easily achieve better phase control resolution through the high-precision design of the vector metasurface template, thereby improving the exposure processing quality of the system.

[0059] At the same time, combined with the projection magnification unit's magnification processing of the vector light field, by adjusting the projection magnification unit, one-time exposure molding of an exposure surface of any size can be achieved according to the exposure processing requirements of the flat liquid crystal optical device.

[0060] On the other hand, some embodiments of the present invention provide an exposure processing method, which uses the exposure processing system in the above embodiments to perform exposure processing.

[0061] In some embodiments, the exposure processing method includes:

[0062] The incident linearly polarized light is decomposed into left-handed circularly polarized light and right-handed circularly polarized light by using the vector metasurface template, and the phases of the left-handed circularly polarized light and the right-handed circularly polarized light are adjusted to the required phases respectively;

[0063] The left-handed circularly polarized light and the right-handed circularly polarized light emitted from the vector metasurface template are amplified by a projection magnification unit, and the left-handed circularly polarized light and the right-handed circularly polarized light after the projection magnification process interfere with each other on an exposure surface to form a vector exposure field, and the planar liquid crystal optical device arranged at the location of the exposure surface is exposed through the formed vector exposure field.

[0064] A vector exposure field of the required processing size is obtained at the exposure surface position through the projection magnification unit, and the exposure processing of large-size flat liquid crystal optical devices can be completed by a single exposure.

[0065] In some embodiments, the exposure processing method further includes the step of processing the light emitted by the laser light source into linearly polarized light.

[0066] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. used to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship commonly placed when the product of the invention is used. They are only for the convenience of describing the present invention 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, and therefore cannot be understood as a limitation on the present invention.

[0067] In addition, if the terms "horizontal" or "vertical" appear in the description of the present invention, it does not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0068] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood in combination with specific circumstances.

[0069] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An exposure processing system, characterized in that: include: A vector metasurface template, wherein the vector metasurface template is used to decompose incident linearly polarized light into left-handed circularly polarized light and right-handed circularly polarized light, and can independently adjust the phases of the left-handed circularly polarized light and the right-handed circularly polarized light, so that the left-handed circularly polarized light and the right-handed circularly polarized light have desired phases, respectively; a projection magnification unit, wherein the projection magnification unit is used to perform projection magnification processing on the left-handed circularly polarized light and the right-handed circularly polarized light emitted from the vector metasurface template, and enable the left-handed circularly polarized light and the right-handed circularly polarized light after the projection magnification processing to interfere on an exposure surface and form a vector exposure field.

2. The exposure processing system according to claim 1, characterized in that: The vector metasurface template adopts a composite phase design so that the vector metasurface template can independently adjust the phases of left-handed circularly polarized light and right-handed circularly polarized light.

3. The exposure processing system according to claim 1, characterized in that: The exposure processing system further includes: a laser light source; a laser processing unit, the laser processing unit being used to pre-process the light beam emitted by the laser light source; and a polarization processing unit, the polarization processing unit being used to process the incident laser light beam into linearly polarized light.

4. The exposure processing system according to claim 3, characterized in that: The laser processing unit includes a spatial filtering unit, a beam expanding unit, a pointing stabilizing unit, and a shaping unit.

5. The exposure processing system according to claim 3, characterized in that: The polarization processing unit comprises a polarizer and a half-wave plate which are sequentially arranged along the light path.

6. The exposure processing system according to claim 5, characterized in that: It also includes a light path folding unit, which is used to change the direction of the light path.

7. An exposure processing method, characterized in that: The exposure processing is performed using the exposure processing system described in any one of claims 1 to 6.

8. The exposure processing method according to claim 7, characterized in that: include: The incident linearly polarized light is decomposed into left-handed circularly polarized light and right-handed circularly polarized light by using the vector metasurface template, and the phases of the left-handed circularly polarized light and the right-handed circularly polarized light are adjusted to the required phases respectively; The left-handed circularly polarized light and the right-handed circularly polarized light emitted from the vector metasurface template are projected and magnified, and the left-handed circularly polarized light and the right-handed circularly polarized light after the projection and magnification process interfere with each other on the exposure surface to form a vector exposure field, and the planar liquid crystal optical device set at the exposure surface is exposed through the formed vector exposure field.

9. The exposure processing method according to claim 8, characterized in that: The method also includes a step of processing the light emitted by the laser light source into linearly polarized light.

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