A method and system for fabricating a polymer microlens array

Abstract

The application discloses a preparation method and system of a polymer microlens array, and comprises the following steps: obtaining different monomer solution standing wave modes corresponding to different vibration parameters, and determining the corresponding relationship between the vibration parameters and the monomer solution standing wave modes; based on the shape and size of the microlens array, obtaining the working vibration parameter according to the corresponding relationship, and obtaining the standing wave mode of the microlens array with the corresponding shape and size on the surface of the monomer solution; using an ultraviolet light curing system to emit ultraviolet light to the surface of the monomer solution, and curing the monomer solution by the ultraviolet light to freeze the wave form, so as to obtain the cured microlens array; compared with the prior art, the application provides a preparation method of optimizing the microlens array, and the microlens array with various geometric shapes can be manufactured in a single and simple step without additional components and molds; the surface of the obtained microlens array has excellent surface quality and has atomic level smoothness.

Description

Technical Field

[0001] This invention relates to the field of micro-optical element technology, and in particular to a method and system for fabricating a polymer microlens array. Background Technology

[0002] Integrating microlens arrays into modern electronic and optical systems is becoming a practical and efficient method to enhance the performance and functionality of these advanced systems. For example, this integration holds immense promise for improving the brightness and efficiency of organic light-emitting diode (OLED) displays and solar energy systems, increasing the accuracy and speed of multi-beam control systems (such as autonomous driving systems), improving fiber optic coupling efficiency, enhancing the imaging quality and sensitivity of optical sensors and cameras, and for applications in cell imaging and tissue engineering in the biomedical field.

[0003] To meet the demands of modern applications, various methods for manufacturing microlens arrays have been introduced. These methods include machining, femtosecond laser technology, ultra-precision diamond turning, photolithography, chemical etching, thermoforming / pressing, nanosecond pulsed electrochemical micromachining (EMM), reactive ion etching, and soft printing. However, all of these technologies are typically complex and inefficient, relying on expensive ultra-precision machine tools and molds, as well as highly experienced skilled technicians.

[0004] For example, machining relies on expensive nanofabrication equipment. The production process is slow and requires skilled operators. Hot pressing improves surface quality, but limitations in cavity filling make it difficult to fabricate microlens arrays with high numerical apertures (NA). Large-scale manufacturing using femtosecond laser technology is inefficient and struggles to guarantee surface quality. Achieving precise fabrication of high NA microlens arrays remains challenging.

[0005] To address these challenges, a series of patents combining micro-replication and UV polymerization technologies have been developed. The currently disclosed technologies have encountered various critical issues that must be resolved. These issues include controlling mold distortion, material loss, environmental stability, and how to precisely adjust the refractive index of optical components.

[0006] Furthermore, patent publication number CN 115356793 A describes a manufacturing process for microlens arrays. This process combines microreplication of metal molds with ultraviolet polymerization technology, enabling the production of lens arrays at room temperature without applying pressure. However, manufacturing the required metal molds remains a key challenge, requiring expensive nanoprecision equipment and tools. Moreover, the surface quality of the mold significantly affects the quality of the microlens arrays.

[0007] Patent CN103353627A outlines a method for manufacturing optical polymers with columnar microporous features using a polymer mold (e.g., SU8) under vacuum conditions. This patent emphasizes the complex, multi-step process required to fabricate the mold with these columnar micro-features, including spin coating, photolithography, heat treatment, and UV polymerization. However, concerns remain regarding the surface quality of the micro-features, particularly the roughness that may manifest on the lens array surface, and the durability of the mold throughout the molding process. Therefore, this complex manufacturing technique significantly impacts the practical and economic feasibility of the method.

[0008] Therefore, a new microlens array manufacturing technology is needed to overcome these difficulties and achieve a simple and cost-effective method for producing flawless structures in high volumes.

[0009] Currently, the fabrication techniques for polymer microlens arrays still require further improvement. Summary of the Invention

[0010] This invention proposes a method and system for fabricating polymer microlens arrays, which solves the technical problems of existing microlens arrays, such as control mold distortion, poor environmental stability, and inability to accurately adjust the refractive index of optical elements.

[0011] To address the above problems, the present invention proposes the following technical solution:

[0012] On one hand, the present invention provides a method for fabricating a polymer microlens array, specifically including the following steps:

[0013] By adjusting the vibration parameters of the monomer solution, the standing wave morphology of the monomer solution corresponding to different vibration parameters is obtained, and the correspondence between the vibration parameters and the standing wave morphology of the monomer solution is determined.

[0014] Based on the shape and size of the microlens array, the working vibration parameters are obtained according to the corresponding relationship, and the standing wave morphology of the microlens with the corresponding shape and size is obtained on the surface of the monomer solution.

[0015] Using an ultraviolet curing system, ultraviolet light is emitted onto the surface of the monomer solution, and the monomer solution is cured by ultraviolet light to freeze the waveform, thereby obtaining a cured microlens array.

[0016] Based on this technical solution, and further preferably, the step of adjusting the vibration parameters of the monomer solution to obtain the correspondence between the vibration parameters and the standing wave morphology of the monomer solution includes the following steps: adjusting the vibration parameters of the monomer solution according to the fluid dynamics equations to obtain the correspondence between the vibration parameters and the standing wave morphology of the monomer solution.

[0017] Based on this technical solution, and further preferably, the step of adjusting the vibration parameters of the monomer solution to obtain the correspondence between the vibration parameters and the standing wave morphology of the monomer solution specifically includes the following steps:

[0018] Based on the numerical solution of the Navier-Stokes equations, the dynamic behavior of the monomer solution after vibration is described. By adjusting the corresponding vibration parameters in the monomer solution, the shape and size of the microlens are designed to obtain the standing wave morphology of the array group distribution. The Navier-Stokes equations are as follows:

[0019] (1) G(t) = g - acos(ωt)

[0020] Where g is the acceleration due to gravity, a is the amplitude, and ω is the angular velocity.

[0021] (2) z = ζ(x,t)

[0022] In this equation (2), the free liquid surface is represented, t is time, z is the coordinate perpendicular to the container plane, and x is the plane coordinate vector.

[0023] (3)

[0024] Equation (3) represents the condition that k satisfies the motion boundary conditions. 2 =k x 2 +k y 2 ,k x Let k be the wave number in the x-direction. y Let ν be the wave number in the y-direction, ν = η / ρ be the kinematic viscosity of the liquid, ρ be the liquid density, η be the dynamic viscosity of the liquid, and w be the velocity of the liquid in the z-direction. By combining the numerical solution of the above Navier-Stokes equations, the shape and size of the microlens can be designed, and the standing wave morphology of the array group distribution can be obtained.

[0025] Based on this technical solution, and further preferably, the vibration parameters include vibration frequency, acceleration, shape, and monomer solution viscosity.

[0026] Based on this technical solution, and more preferably, the shape of the microlens includes circular and rectangular.

[0027] Based on this technical solution, and more preferably, the viscosity of the monomer solution is 10-140 cps.

[0028] Based on this technical solution, and more preferably, the vibration frequency includes 30-900Hz.

[0029] The shape and size of the microlens array include: the shape and size of individual microlenses, wherein the shape of the individual microlens includes circular and rectangular, and the size of the individual microlens includes a diameter of 50-70 mm.

[0030] Based on this technical solution, and further preferably, the emission of ultraviolet light onto the surface of the monomer solution includes single-frequency or multi-frequency waves.

[0031] Based on this technical solution, a further preferred embodiment of the method for fabricating a polymer microlens array is as follows:

[0032] On a container filled with a UV-curable monomer solution with high optical transparency, oscillations are applied to excite stable surface standing waves of the desired shape, size, and distribution, and then UV light is applied to cure the monomer solution with stable surface waves.

[0033] On the other hand, the present invention also provides a fabrication system for a polymer microlens array, including a vibration system, a containment system, an ultraviolet curing system, and a mounting bracket.

[0034] The containment system includes a liquid container and a monomer solution;

[0035] The vibration system includes a vibrator and a vibrator head plate, and the vibration system is disposed on one side of the containment system to obtain the standing wave morphology of the monomer solution;

[0036] The ultraviolet curing system is arranged parallel to the containment system on the side away from the vibration system and is connected to the containment system through the mounting bracket, and is used to cure the monomer solution.

[0037] Compared with the prior art, the technical effects achieved by the present invention include:

[0038] In view of the shortcomings of existing microlens array manufacturing technology, the present invention provides a novel and simple method that can effectively eliminate various constraints of external processing conditions, such as expensive nanoscale multi-axis machining centers, ultra-precision tools and molds. With the preparation method provided by the present invention, the production of defect-free polymer microlens arrays can be completed efficiently and at low cost, and the production process no longer depends on the processing of high-precision tools and molds.

[0039] The method and system for fabricating polymer microlens arrays described in this invention overcome the shortcomings of existing technologies. It allows for the instantaneous switching of the shape, size, and distribution of stable surface standing waves by manipulating vibration parameters, the viscosity of the monomer solution, the container shape, and liquid properties (e.g., viscosity), with a very wide switching range, including striped, hexagonal, square, and quasi-periodic shapes. Because the standing waves of the monomer solution possess atomic-scale surface optical cleanliness under surface tension, the cured microlenses naturally possess atomic-scale surface optical quality, completely and easily avoiding surface damage caused by other existing production technologies.

[0040] Meanwhile, the design of stable standing wave morphology for polymer microlens arrays in this invention is based on the fundamental theory of the Navier-Stokes equations. Therefore, its technical solution also opens up a new path for the further development of manufacturing technology for microlens arrays and similar products. Attached Figure Description

[0041] Figure 1 This is a flowchart of the fabrication method of the polymer microlens array described in this invention;

[0042] Figure 2 This is the fabrication system for the polymer microlens array described in Example 1 of the present invention;

[0043] Figure 3 This is the stable standing wave morphology of the polymer microlens array predicted by the numerical solution of the Navier-Stokes equation in Embodiment 2 of the present invention.

[0044] Figure 4 The stable standing wave morphology of the polymer microlens array actually prepared in Example 3 of this invention;

[0045] 1-Vibrator; 2-Vibrator head plate; 3-Liquid container; 4-Monomer solution; 5-UV curing system; 6-Polymer microlens array; 7-Monomer microlens; 8-Standing wave morphology of microlens array. Detailed Implementation

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art based on the technology to which the claims of the present invention pertain without creative effort are within the scope of protection of the present invention.

[0047] It should be understood that the terminology used in this specification of embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. As used in this specification of embodiments of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0048] Currently, the theoretical and knowledge base for the design and fabrication of microlens arrays is based on three mechanisms: 1. Material removal mechanisms (involving nanofabrication, etching, and laser ablation techniques); 2. Deformation mechanisms, often combined with material removal, including molding and forming techniques; and 3. Material addition mechanisms, including microjetting and additive manufacturing techniques. Techniques based on mechanisms 1 and 2 inevitably suffer damage due to material removal and deformation, while techniques related to mechanism 3 encounter challenges related to surface integrity, such as poor surface roughness and uncertain shape distortion due to unpredictable residual stress.

[0049] Compared to the three existing mechanisms, this invention abandons all existing microlens array manufacturing technologies and provides a completely new method and technology that can manufacture defect-free polymer microlens arrays at room temperature. The specific fabrication process of the polymer microlens array is shown in the flowchart below. Figure 1 When a liquid is placed in a vibrating open container, a stable standing wave pattern appears on its surface. Different vibration frequencies and amplitudes produce a variety of stable waveforms, including stripes, hexagons, squares, or quasi-periodic patterns. Furthermore, changing the container shape (e.g., circular or rectangular), adjusting liquid properties (e.g., viscosity), or altering the vibration mode (e.g., single-frequency or multi-frequency) can yield even more diverse and complex waveform morphologies. The desired morphology and geometry (including substrate size and height) of a microlens array can be controlled by adjusting vibration parameters and liquid properties.

[0050] Example 1

[0051] This invention provides a fabrication system for polymer microlens arrays, including a vibration system, a containment system, an ultraviolet curing system, and a mounting bracket.

[0052] The vibration system includes a vibrator 1 and a vibrator head plate 2, and the vibration system is disposed on one side of the containment system for generating a stable standing wave pattern of the monomer solution.

[0053] The containment system includes a liquid container 3 and a monomer solution 4;

[0054] The ultraviolet curing system is arranged parallel to the containment system on the side away from the vibration system and is connected to the containment system through the mounting bracket, and is used to cure the monomer solution.

[0055] like Figure 2 As shown, the vibration system includes a vibrator 1 and a vibrator head plate 2, used to generate stable surface standing waves of monomer solution 4 in the liquid container 3. The vibrator 1 is equipped with a closed-loop amplifier system, which can generate stable surface standing wave morphologies of various geometries, sizes and distributions by adjusting relevant vibration parameters, such as adjusting the vibration frequency (30-900Hz), adjusting the container size diameter (50-70mm), the shape (including circular and rectangular), and the thickness of the monomer liquid layer (ranging from several micrometers to several millimeters).

[0056] The vibrator head plate 2 is installed on the vibrator head of the vibrator 1, and the liquid container 3 is fixed on the vibrator head plate 2.

[0057] On the other hand, the geometry and size of the liquid container 3 affect the generation of stable standing waves on the surface of the monomer solution 4, an effect caused by boundary effects. Therefore, appropriate containers can be selected as needed to utilize various containers with different geometries and sizes.

[0058] The size and shape of the liquid container 3 need to be adjusted according to the stable geometry of the surface standing wave, the requirements of the boundary effect, and the requirements of the microlens array. For example, to generate a stable square pattern, a circular container with a diameter of 60 mm or more can be used.

[0059] The UV curing system 5 uses UV light with a peak wavelength of 360-370nm and is mounted parallel to the liquid container 3 using a mounting bracket. The distance between the UV curing system 5 and the surface of the monomer solution 4 is adjustable using the mounting bracket. The monomer solution 4 can be rapidly cured or frozen in a very short time (e.g., 3-5 seconds). The instantaneous freezing of the monomer solution during the standing wave allows for precise control of the size and geometry of the pattern.

[0060] same Figure 2 The fabrication process of the polymer microlens array 6 is as follows. In this embodiment, the polymer microlens array 6 consists of a 5×5 lens 7. Each lens element has a diameter. Although the individual lenses in the figure all appear to have a circular base, their shape, size, and distribution can be switched at any time by changing vibration parameters, such as frequency (30-900Hz), monomer solution viscosity (10-140cps), container shape, and liquid properties (viscosity), such as concave or convex stripes, hexagons, squares, quasi-periodic shapes, etc.; 8 represents the standing wave morphology of the microlens array. It is evident that in this embodiment, the shape, size, and distribution of the microlens array can be effectively switched by adjusting the vibration parameters of the monomer solution and the properties of the solution.

[0061] Example 2

[0062] This embodiment provides a method for fabricating a polymer microlens array, including the following steps:

[0063] S1. Adjust the vibration parameters of the monomer solution to obtain the standing wave morphology of the monomer solution corresponding to different vibration parameters, and determine the correspondence between the vibration parameters and the standing wave morphology of the monomer solution.

[0064] Specifically, based on the numerical solution of the Navier-Stokes equations, the dynamic behavior of the monomer solution after vibration is described. By adjusting the corresponding vibration parameters in the monomer solution, the shape and size of the microlens are designed to obtain the standing wave morphology of the array group distribution. The Navier-Stokes equations are as follows:

[0065] G(t) = g - acos(ωt)

[0066] Where g is the acceleration due to gravity, a is the amplitude, and ω is the angular velocity.

[0067] z = ζ(x,t)

[0068] This equation represents the free liquid surface, where t is time, z is the coordinate perpendicular to the container plane, and x is the plane coordinate vector.

[0069]

[0070] This equation indicates that the motion boundary conditions are satisfied, k 2 =k x 2 +k y 2 ,k x Let k be the wave number in the x-direction. y Let ν be the wave number in the y-direction, ν = η / ρ be the kinematic viscosity of the liquid, ρ be the liquid density, η be the dynamic viscosity of the liquid, and w be the velocity of the liquid in the z-direction. By combining the numerical solution of the above Navier-Stokes equations, the shape, size, and viscosity of the microlens can be designed to obtain the standing wave morphology of the monomer solution.

[0071] The reason is that the free surface of a liquid layer generates surface waves when it vibrates periodically. Once the driving amplitude exceeds a critical threshold, standing waves are generated, and the surface morphology depends on the driving frequency and the properties of the liquid (including viscosity, surface tension, and density). These properties, including vibration frequencies of 30-900 Hz, monomer solution viscosity of 10-140 cps, and microlens diameter of 50-70 mm, can effectively enable the morphology switching of polymer microlens arrays. For example, liquids with lower viscosity often correspond to hexagonal surface morphology at low frequencies, while exhibiting square patterns at high frequencies.

[0072] S2. Based on the shape and size of the microlens array, the working vibration parameters are obtained according to the corresponding relationship, and the standing wave morphology of the microlens with the corresponding shape and size is obtained on the surface of the monomer solution.

[0073] Specifically, such as Figure 3 , Figure 3 The stable standing wave morphology of the polymer microlens array predicted by the numerical solution of the Navier-Stokes equation in this embodiment is as follows: According to the above equation, the polymer with a low viscosity of 13.5 cps will generate a hexagonal stable standing wave surface at a vibration frequency of 28 Hz, and a square stable standing wave surface at 30.1 Hz.

[0074] S3. Using an ultraviolet curing system, ultraviolet light is emitted onto the surface of the monomer solution described in S1, and the monomer solution is cured by ultraviolet light to freeze the waveform, thereby obtaining a cured microlens array.

[0075] Specifically, when modulating various nonlinear vibration standing waves, including but not limited to single-frequency or multi-frequency waves introduced in this embodiment, such modulation helps to generate stable, predictable and controllable standing wave morphologies on the surface of monomeric solutions.

[0076] Example 3

[0077] This embodiment provides a method for fabricating a polymer microlens array, specifically including the following steps:

[0078] S1. Adjust the vibration parameters of the monomer solution to obtain the standing wave morphology of the monomer solution corresponding to different vibration parameters, and determine the correspondence between the vibration parameters and the standing wave morphology of the monomer solution.

[0079] Specifically, based on the numerical solution of the Navier-Stokes equations, the dynamic behavior of the monomer solution after vibration is described. By adjusting the corresponding vibration parameters in the monomer solution, the shape and size of the microlens are designed to obtain the standing wave morphology of the array group distribution. The Navier-Stokes equations are as follows:

[0080] G(t) = g - acos(ωt)

[0081] z = ζ(x,t)

[0082]

[0083] S2. Based on the shape and size of the microlens array, the working vibration parameters are obtained according to the corresponding relationship, and the standing wave morphology of the microlens with the corresponding shape and size is obtained on the surface of the monomer solution.

[0084] The monomer solution described in this embodiment is NOA89 solution. The viscosity of NOA89 solution is 15-20 cps. The diameter of the liquid container is 50 mm. When the vibration frequency is 30 Hz, the shape, size, and viscosity of the microlens can be designed by combining the numerical solution of the Navier-Stokes equation to obtain the standing wave morphology of the NOA89 solution.

[0085] S3. Using an ultraviolet curing system, ultraviolet light is emitted onto the surface of the monomer solution described in S1, and the monomer solution is cured by ultraviolet light to freeze the waveform, thereby obtaining a cured microlens array.

[0086] Specifically, it can be cured after being irradiated with ultraviolet light. The peak wavelength of ultraviolet light is 360-370nm. The curing process usually consists of two steps. The first step is a short pre-curing. The pre-curing time should be such that it can basically position and bond the object, but also allow for slight adjustments without affecting its alignment. After this pre-curing, a longer curing time is performed with ultraviolet light. Pre-curing can be achieved by using a 100-watt mercury lamp, at a distance of 6 inches, for 10 seconds.

[0087] Specifically, such as Figure 4 , Figure 4 The polymer microlens array actually prepared in this embodiment shows that the surface of the resulting microlens array has high surface quality, i.e., atomic-level smoothness. This is mainly due to the inherent surface tension characteristics of the liquid. Therefore, these surfaces are clean and can provide the highest optical quality. Furthermore, surface damage problems caused by existing technologies are completely and naturally avoided without any measures.

[0088] In summary, this invention provides a system for fabricating polymer microlens arrays, which can rapidly manufacture microlens arrays with a preset geometry by "instantly freezing" waveforms in a liquid. This design lays a solid foundation for the technological development of the field of microlens array manufacturing.

[0089] It also provides an optimized method for fabricating microlens arrays, which can manufacture microlens arrays with diverse geometries in a single, simple step without the need for additional components and molds, effectively overcoming existing manufacturing limitations.

[0090] Once the waveform is solidified, the resulting microlens array surface possesses exceptional surface quality, exhibiting atomic-level smoothness. This is primarily due to the inherent surface tension properties of the liquid. Consequently, these surfaces are clean, providing the highest optical quality. Furthermore, surface damage issues arising from existing technologies are completely and naturally avoided without any intervention.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for fabricating a polymer microlens array, characterized in that, Includes the following steps: By adjusting the vibration parameters of the monomer solution, the standing wave morphology of the monomer solution corresponding to different vibration parameters is obtained, and the correspondence between the vibration parameters and the standing wave morphology of the monomer solution is determined. Based on the shape and size of the microlens array, the working vibration parameters are obtained according to the corresponding relationship, and the standing wave morphology of the microlens array with the corresponding shape and size is obtained on the surface of the monomer solution. Using an ultraviolet curing system, ultraviolet light is emitted onto the surface of the monomer solution, and the monomer solution is cured by ultraviolet light to freeze the waveform, thereby obtaining a cured microlens array; The adjustment of the vibration parameters of the monomer solution to obtain the correspondence between the vibration parameters and the standing wave morphology of the monomer solution includes: Based on the numerical solution of the Navier-Stokes equations, the dynamic behavior of the monomer solution after vibration is described. By adjusting the corresponding vibration parameters in the monomer solution, the shape and size of the microlens are designed to obtain the standing wave morphology of the array group distribution. The Navier-Stokes equations are as follows: Where g is the acceleration due to gravity, a is the amplitude, ω is the angular velocity, and t is the time. in, t For time, z The coordinates are perpendicular to the plane of the container. x It is a planar coordinate vector. in, k 2 =k x 2 +k y 2 , k x for x Wave number in direction, k y for y Wave number in direction, ν = η / ρ The kinematic viscosity of the liquid. ρ For the density of the liquid, η The dynamic viscosity of the liquid. w liquid z By combining the velocity in the direction with the numerical solution of the Navier-Stokes equations, the shape and size of the microlens can be designed, and the standing wave morphology of the array group distribution can be obtained.

2. The method for fabricating the polymer microlens array as described in claim 1, characterized in that, The vibration parameters include vibration frequency, acceleration, shape, and monomer solution viscosity.

3. The method for fabricating the polymer microlens array as described in claim 1, characterized in that, The shape and size of the microlens array include: the shape and size of individual microlenses, wherein the shape of the individual microlenses includes circular and rectangular.

4. The method for fabricating the polymer microlens array as described in claim 2, characterized in that, The viscosity of the monomer solution is 10-140 cps.

5. The method for fabricating the polymer microlens array as described in claim 2, characterized in that, The vibration frequency is 30-900Hz.

6. The method for fabricating the polymer microlens array as described in claim 1, characterized in that, The emission of ultraviolet light onto the surface of the monomer solution includes single-frequency or multi-frequency waves.

7. A system for fabricating a polymer microlens array, using the method for fabricating a polymer microlens array according to any one of claims 1 to 6, characterized in that, Includes a vibration system, a containment system, a UV curing system, and mounting brackets. The containment system includes a liquid container and a monomer solution. The vibration system includes a vibrator and a vibrator head plate, and the vibration system is disposed on one side of the containment system to obtain the standing wave morphology of the monomer solution; The ultraviolet curing system is arranged parallel to the containment system on the side away from the vibration system and is connected to the containment system through the mounting bracket, and is used to cure the monomer solution.

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