A method for preparing a microlens array

Abstract

The present invention belongs to the field of microlens technology, and specifically relates to a method for preparing a microlens array. The present invention provides a method for preparing a microlens array, comprising the following steps: dispersing micro-nanospheres in a film-forming agent to obtain a dispersion; forming the dispersion into a film to obtain a film with micro-nanospheres attached; utilizing optical pressure to assemble the micro-nanospheres attached to the surface of the film into an array to obtain a film containing a micro-nanosphere array; and transferring the film containing the micro-nanosphere array to a substrate surface to obtain the microlens array. The present invention utilizes optical pressure to assemble the micro-nanospheres attached to the surface of a water film, and does not require a large device with an optical tweezers system to manipulate the micro-nanospheres on the film. The assembled material can be directly transferred to the substrate surface without undergoing special treatment to obtain a microlens array. The preparation method provided by the present invention is simple and easy to operate.

Description

Technical Field

[0001] The present invention belongs to the technical field of microlenses, and in particular relates to a method for preparing a microlens array. Background Art

[0002] A microlens consists of a substrate and an array of micro-nanospheres on its surface. The micro-nanosphere array is composed of units with diameters ranging from a few hundred nanometers to a few microns. Because each unit in the micro-nanosphere array has a unique optical axis, when all units are considered as an array as a whole, they also have a main optical axis. Compared with traditional single lenses, microlenses have extremely high parallelism. Each unit can transmit optical signals independently without interfering with each other. This is equivalent to the existence of a large number of two-dimensional parallel optical paths, and each array unit has the function of transmitting, transforming, and imaging optical information. Microlenses can perform functions that traditional optical components cannot, and are the core components of many new optical systems, such as Shack-Hartmann wavefront sensors, infrared focal plane detection or CCD array light focusing, laser array scanning, laser display, fiber coupling, beam homogenization, and beam shaping.

[0003] Currently, microlens array fabrication methods primarily include photoresist melting, reactive ion beam etching, microjet printing, laser direct writing, electrowetting molding, and nanoimprinting. However, these existing methods all require large-scale equipment with optical tweezers systems, making their operation relatively complex. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing a microlens array. The preparation method provided by the present invention does not require a large optical tweezers system and is simple to operate.

[0005] In order to solve the above technical problems, the present invention provides a method for preparing a microlens array, comprising the following steps:

[0006] dispersing the micro-nanospheres in a film-forming agent to obtain a dispersion;

[0007] forming the dispersion into a film to obtain a water film with attached micro-nanospheres;

[0008] After the micro-nanospheres attached to the surface of the water film are assembled into an array using light pressure, a water film containing the micro-nanosphere array is obtained;

[0009] The water film containing the micro-nanosphere array is transferred to the surface of a substrate to obtain the microlens array.

[0010] Preferably, the dispersing comprises the following steps:

[0011] Mixing the micro-nanospheres and water to obtain a micro-nanosphere stock solution;

[0012] The micro-nanosphere stock solution and the film-forming agent are mixed to obtain the dispersion.

[0013] Preferably, the micro-nanospheres include polystyrene micro-nanospheres, silica micro-nanospheres, titanium dioxide micro-nanospheres or polymethyl methacrylate micro-nanospheres.

[0014] Preferably, the average particle size of the micro-nanospheres is 2 to 5 μm.

[0015] Preferably, the mass concentration of the micro-nanosphere stock solution is 2-3%.

[0016] Preferably, the volume ratio of the micro-nanosphere stock solution to the film-forming agent is 5:1800-2200.

[0017] Preferably, the light source for generating the optical pressure includes a laser.

[0018] Preferably, the light pressure is 0.667-1 pN.

[0019] Preferably, the substrate comprises a polydimethylsiloxane film.

[0020] Preferably, the transfer comprises the following steps:

[0021] After the water film containing the micro-nanosphere array is suspended in the air, the substrate is penetrated from bottom to top through the water film containing the micro-nanosphere array.

[0022] The present invention provides a method for preparing a microlens array, comprising the following steps: dispersing micro-nanospheres in a film-forming agent to obtain a dispersion; forming the dispersion into a film to obtain a water film with attached micro-nanospheres; utilizing optical pressure to assemble the micro-nanospheres attached to the surface of the water film into an array, thereby obtaining a water film containing the micro-nanosphere array; and transferring the water film containing the micro-nanosphere array to a substrate surface to obtain the microlens array. The present invention utilizes optical pressure to assemble the micro-nanospheres attached to the surface of the water film, eliminating the need for a large device with an optical tweezers system to manipulate the micro-nanospheres on the film. The assembled material can be directly transferred to the substrate surface without undergoing any special processing to obtain the microlens array. The preparation method provided by the present invention is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of assembling micro-nanosphere arrays of different shapes using light pressure;

[0024] Figure 2 Microscopic images of the shapes of the micro-nanosphere modules prepared at different times in Examples 1 to 3;

[0025] Figure 3 Micrographs of the microlens arrays prepared in Examples 1, 4, and 5;

[0026] Figure 4Schematic diagram of the process of transferring the micro-nanosphere array prepared in Example 6 to a substrate;

[0027] Figure 5 Schematic diagram of the process of longitudinal and transverse deformation of a circle in Example 7, where a represents longitudinal deformation and b represents transverse deformation;

[0028] Figure 6 These are actual pictures of the circular micro-nanosphere array, the deformed triangular-shaped micro-nanosphere array, the deformed strip-shaped micro-nanosphere array, and the deformed heart-shaped micro-nanosphere array in Example 7. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing a microlens array, comprising the following steps:

[0030] dispersing the micro-nanospheres in a film-forming agent to obtain a dispersion;

[0031] forming the dispersion into a film to obtain a water film with attached micro-nanospheres;

[0032] After the micro-nanospheres attached to the surface of the water film are assembled into an array using light pressure, a water film containing the micro-nanosphere array is obtained;

[0033] The water film containing the micro-nanosphere array is transferred to the surface of a substrate to obtain the microlens array.

[0034] In the present invention, unless otherwise specified, all raw materials are conventional commercially available products.

[0035] The present invention disperses micro-nanospheres in a film-forming agent to obtain a dispersion.

[0036] In the present invention, the dispersing preferably comprises the following steps:

[0037] Mixing the micro-nanospheres and water to obtain a micro-nanosphere stock solution;

[0038] The micro-nanosphere stock solution and the film-forming agent are mixed to obtain the dispersion.

[0039] The present invention mixes micro-nanospheres and water to obtain a micro-nanosphere stock solution. In the present invention, the water is preferably deionized water. In the present invention, the average particle size of the micro-nanospheres is preferably 2 to 5 μm, more preferably 3 to 5 μm. In the present invention, the micro-nanospheres preferably include polystyrene (PS) micro-nanospheres, silica micro-nanospheres, titanium dioxide micro-nanospheres or polymethyl methacrylate (PMMA) micro-nanospheres, more preferably polystyrene micro-nanospheres. In the present invention, the mass concentration of the micro-nanosphere stock solution is preferably 2 to 3%, more preferably 2.3 to 2.5%.

[0040] The present invention has no special requirements for the mixing, as long as the mixing can be uniform.

[0041] After obtaining the micro-nanosphere stock solution, the present invention mixes the micro-nanosphere stock solution with a film-forming agent to obtain the dispersion. In the present invention, the film-forming agent is preferably a mixture of water and a surfactant; the surfactant is not particularly limited in the present invention, as long as it can form a flexible water film. In the present invention, the film-forming agent is preferably a mixture of glycerin, hand soap, and water; the film-forming agent is preferably prepared according to the following method:

[0042] Glycerin and hand soap are dissolved in water and then filtered to obtain the film-forming agent.

[0043] In the present invention, the water is preferably deionized water; the hand soap is preferably Dettol hand soap. In the present invention, the volume ratio of water to glycerin is preferably 3.8-4.2:1, more preferably 4:1; the volume ratio of water to hand soap is preferably 3.8-4.2:0.05-0.1, more preferably 4:0.08-0.1.

[0044] The present invention has no special requirements for the dissolution, as long as it can be dissolved evenly.

[0045] In the present invention, the pore size of the filter is preferably 0.8 to 1.2 μm, more preferably 1 μm. The present invention removes foam generated after mixing by filtration. The present invention does not specifically limit the filtration method, as long as it can remove foam. In an embodiment of the present invention, filtration is performed using a disposable syringe with a filter at the needle tip.

[0046] In the present invention, the volume ratio of the micro-nanosphere stock solution to the film-forming agent is preferably 5:1800-2200, more preferably 5:2000.

[0047] The present invention has no special requirements for the mixing, as long as the mixing can be uniform.

[0048] After obtaining the dispersion, the present invention forms a film of the dispersion to obtain a water film with attached micro-nanospheres. In the present invention, the film forming preferably includes the following steps:

[0049] The rubber ring is immersed in the dispersion and then pulled up to obtain a water film with attached micro-nanospheres.

[0050] In the present invention, the diameter of the rubber ring is preferably 3 cm or more, more preferably 4 to 6 cm. After the water film is formed, the rubber ring is preferably placed on the surface of a glass slide, and the glass slide with the rubber ring is placed on the surface of a two-dimensional displacement platform of a microscope for standby use.

[0051] After obtaining a water film with attached micro-nanospheres, the present invention uses optical pressure to assemble the micro-nanospheres attached to the surface of the water film into an array, thereby obtaining a water film containing a micro-nanosphere array. In the present invention, the light source for generating the optical pressure preferably includes a laser, and the laser is preferably a fiber laser. In the present invention, the fiber laser is preferably generated by passing the laser through a tapered optical fiber. In the present invention, the wavelength of the laser is preferably 800-810 nm, more preferably 808 nm; the power of the laser is preferably 30-45 mW, more preferably 30-40 mW.

[0052] In the present invention, the tapered optical fiber taper is preferably prepared according to the following method:

[0053] Use fiber optic strippers to remove the plastic protective cover and cladding of the single-mode optical fiber, leaving the fiber core exposed for 20 to 30 cm. Pass the optical fiber through an iron optical fiber protective tube, pull out the end with the cladding stripped, and heat it with the outer flame of an alcohol lamp for 60 to 120 seconds until the optical fiber begins to melt. Pull the optical fiber above the flame at a speed of 2 to 20 mm / s, forming a tapered end at the end of the optical fiber to obtain a tapered optical fiber.

[0054] Tapered optical fibers have a converging effect on light. When the converged light acts on the water film, it can produce optical pressure in a smaller area, achieving higher-resolution control.

[0055] In the present invention, the optical pressure is preferably 0.667 to 1 pN, more preferably 0.7 to 0.9 pN.

[0056] In the present invention, the assembly utilizes light pressure to regulate the position of the micro-nanospheres. The present invention can control the range of regulation by adjusting the distance between the tapered optical fiber and the micro-nanospheres, and control the direction of movement of the micro-nanospheres by adjusting the angle between the tapered optical fiber and the micro-nanospheres. The present invention preferably fixes the tapered optical fiber on an adjustment frame to adjust the relationship between the distance and angle between the tapered optical fiber and the micro-nanospheres. In the present invention, the tapered optical fiber is preferably placed in a protective tube before being fixed. In the present invention, the accuracy of the adjustment frame is preferably 448 to 52 nm, more preferably 50 nm.

[0057] In the present invention, the distance between the tapered optical fiber and the water film with attached micro-nanospheres is preferably 0.1 to 0.5 cm. When the tapered optical fiber is 0.1 cm above the water film, the laser power is 30 mW and the wavelength is 808 nm, the radius of the adjustable range is 10 μm.

[0058] Because the micro-nanospheres attached to the surface of the water film will slightly sink on the water film, the thickness of the water film with and without micro-nanospheres attached is different. This thickness difference will cause interference when there is light, resulting in the appearance of colored peripheral stripes around the micro-nanospheres. The shape of this peripheral stripe is correlated to the shape of the micro-nanosphere array, and the shape of the peripheral stripe is basically consistent with the shape of the micro-nanosphere array. The present application preferably regulates the shape of the internal micro-nanosphere module by applying light pressure to the peripheral stripes. For example, when the light pressure is used to squeeze the peripheral stripes inward, the micro-nanospheres will also have a squeezing effect, and when the stripes are pushed outward, the micro-nanospheres will also have an outward squeezing effect. The present invention uses light pressure to squeeze the peripheral stripes to more accurately control the movement of the micro-nanospheres. In the present invention, the micro-nanosphere module is preferably a product with a certain shape assembled from micro-nanospheres.

[0059] The present invention uses light pressure to control the movement and rotation of micro-nanospheres on the surface of the water film, and can tightly inlay and assemble the micro-nanospheres into the target area from the required angle. For example, if the individual micro-nanospheres are assembled together in an equilateral triangle arrangement to form the central part of the equilateral triangle module, the peripheral micro-nanospheres are assembled into the gaps in the central part, and then they can be stacked outward layer by layer to obtain an equilateral triangle with gradually increasing scale. If the individual micro-nanospheres are assembled together in an equilateral hexagon arrangement to form the central part of the equilateral hexagon module, the outer layer of micro-nanospheres are assembled into the gaps in the central part, and then they can be stacked outward layer by layer to obtain a regular hexagon with gradually increasing scale. If the individual micro-nanospheres are assembled together in a rhombus arrangement to form the central part of the rhombus module, the outer layer of micro-nanospheres are assembled into the gaps in the central part, and then they can be stacked outward layer by layer to obtain a rhombus with gradually increasing scale. Figure 1 Schematic diagram of using light pressure to assemble micro-nanosphere arrays of different shapes.

[0060] After assembly, the present invention can obtain any shape, and at the same time, light pressure can be used to reorganize and deform the assembled shape to obtain a new shape. In the present invention, the reorganization and deformation is preferably to apply light pressure to the outer stripes of the micro-nanosphere array to reshape it. For example, the tapered optical fiber is moved to the outer stripes of the assembled large-scale micro-nanosphere module, and the light pressure is applied to the outer stripes. Using an adjustment frame to move the light pressure away from the stripes can achieve stretching of the outer stripes. As the outer stripes are stretched, the internal large-scale micro-nanosphere module is also stretched. In addition, using an adjustment frame to move the optical fiber close to the stripes can achieve compression of the outer stripes. As the outer stripes are compressed, the internal large-scale micro-nanosphere module is also compressed. When the light pressure is brought close to or away from the outer stripes of the module from different angles, the shape of the large module can be changed from different angles, and then the large module is deformed and reconstructed into different shapes such as circle, triangle, ellipse and heart shape, thereby achieving deformation reconstruction of the assembled module.

[0061] After obtaining the water film containing the micro-nanosphere array, the present invention transfers the water film containing the micro-nanosphere array to a substrate surface to obtain the microlens array. In the present invention, the substrate preferably comprises a polydimethylsiloxane film (PDMS).

[0062] In the present invention, the transfer preferably comprises the following steps:

[0063] After the water film containing the micro-nanosphere array is suspended in the air, the substrate is penetrated from bottom to top through the water film containing the micro-nanosphere array.

[0064] The present invention preferably suspends the water film containing the micro-nanosphere array in the air by the following method: using a clamp to clamp the rubber ring used for film formation.

[0065] In the present invention, a water film containing a micro-nanosphere array is suspended in mid-air and preferably placed on a two-dimensional displacement platform of a microscope. After a substrate is placed on the surface of the lifting platform, the lifting platform is used to move the substrate upward through the water film containing the micro-nanosphere array, so that the micro-nanosphere array adheres to the substrate surface.

[0066] The preparation method provided by the present invention does not require the assistance of a template during the assembly process, causes less light damage and thermal damage to the material, can directly, conveniently and non-destructively transfer the assembled micro-nanosphere array to the substrate surface, uses simple materials and equipment, and is low-cost.

[0067] In the micro-nanosphere array assembled according to the preparation method provided by the present invention, adjacent micro-nanospheres are tightly bound by intermolecular interactions, thereby improving the compactness and regularity of the micro-nanosphere array. The preparation method provided by the present invention can reconstruct the assembled micro-nanosphere array.

[0068] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0069] Example 1

[0070] Use fiber strippers to remove the plastic protective cover and cladding of a single-mode optical fiber, exposing a 25 cm length of the fiber core. Pass the fiber through an iron fiber protection tube, pull out the stripped end, and heat it with the outer flame of an alcohol lamp for 100 seconds. Then, pull the fiber above the flame at a speed of 10 mm / s, forming a tapered end at the end of the fiber to obtain a tapered optical fiber.

[0071] Deionized water, glycerin, and Dettol hand soap were mixed in a volume ratio of 4:1:0.05 to obtain a mixed solution; the mixed solution was filtered using a disposable syringe with a filter screen having a pore size of 1 μm at the needle tip to remove foam to obtain a film-forming agent;

[0072] Dispersing polystyrene micro-nanospheres with an average particle size of 3 μm in water to obtain a polystyrene micro-nanosphere stock solution with a mass concentration of 2.5%;

[0073] Mix 5 μL of polystyrene micro-nanosphere stock solution and 2 mL of film-forming agent to obtain a dispersion;

[0074] A rubber ring with a diameter of 3 cm was immersed in the dispersion, and after being pulled up, the rubber ring was placed on the surface of a glass slide to obtain a water film with attached micro-nanospheres;

[0075] A water film with attached micro-nanospheres was placed on the surface of a two-dimensional displacement platform of a microscope; a tapered optical fiber was placed in an iron optical fiber protective tube, which was fixed to an adjustment frame. A laser with a wavelength of 808nm and a power of 30mW was introduced into the tapered optical fiber. The polystyrene micro-nanospheres on the surface of the water film were moved and rotated using a laser light pressure of 0.66pN (the light pressure and the regulation range were controlled by adjusting the distance and angle between the tapered optical fiber and the micro-nanospheres), thereby obtaining a water film containing a diamond-shaped micro-nanosphere array;

[0076] Two clamps placed on a two-dimensional shift platform are used to fix the rubber ring at two symmetrical positions to keep it stably suspended in the air. The two-dimensional shift platform is adjusted to allow the assembled micro-nanosphere array to appear in the field of view of the microscope. A polydimethylsiloxane film is placed on the surface of the lifting platform and moved to directly below the micro-nanosphere array to be transferred. The lifting platform is raised to allow the polydimethylsiloxane film to penetrate the water film containing the diamond-shaped micro-nanosphere array and allow the diamond-shaped micro-nanosphere array to adhere to the surface of the polydimethylsiloxane film to obtain a microlens array.

[0077] Example 2

[0078] A microlens array was prepared according to the method of Example 1, except that the shape of the micro-nanosphere array was regulated to be hexagonal by using light pressure.

[0079] Example 3

[0080] A microlens array was prepared according to the method of Example 1, except that the shape of the micro-nanosphere array was regulated to be triangular by using light pressure.

[0081] Example 4

[0082] A microlens array was prepared according to the method of Example 1, except that the polystyrene micro-nanospheres were replaced with silicon dioxide micro-nanospheres with an average diameter of 3 μm.

[0083] Example 5

[0084] A microlens array was prepared according to the method of Example 1, except that the polystyrene micro-nanospheres were replaced with polymethyl methacrylate micro-nanospheres with an average diameter of 3 μm.

[0085] The shapes of the micro-nanosphere arrays prepared at different times in Examples 1 to 3 were monitored using a 3D microscope, and micrographs of the micro-nanosphere array modules assembled at different times were obtained, as shown in FIG. Figure 2 The present invention utilizes light pressure to move and rotate micro-nanospheres to assemble into micro-nanosphere arrays of different shapes.

[0086] The microlens arrays prepared in Example 1, Example 4 and Example 5 were examined by 3D microscope to obtain micrographs, as shown in FIG. Figure 3 As shown. Figure 3 It can be seen that the arrangement structure of the array transferred from the water film to the substrate maintains its original compactness and regularity.

[0087] Example 6

[0088] The microlens array was prepared according to the method of Example 1, except that four micro-nanosphere arrays were formed on the surface of the water film using light pressure, and the shapes of the four micro-nanosphere arrays were hexagonal, diamond, heart-shaped and rectangular.

[0089] Figure 4 This is a schematic diagram of the process of transferring the four micro-nanosphere arrays prepared in Example 6 to a substrate. The water film containing the micro-nanosphere array is fixed in mid-air, and the substrate is penetrated through the water film to obtain a microlens array.

[0090] Example 7

[0091] A water film containing a micro-nanosphere array was prepared according to the method of Example 1, except that the shape of the micro-nanosphere array was regulated to be circular by light pressure;

[0092] A laser with a wavelength of 808nm and a power of 30mW is introduced into the tapered optical fiber to generate light pressure (the light pressure and regulation range are controlled by adjusting the distance and angle between the tapered optical fiber and the peripheral stripes). The peripheral stripes formed by the micro-nanosphere array on the surface of the water film are squeezed or stretched to reconstruct the shape of the micro-nanosphere array and obtain a micro-nanosphere array of a new shape.

[0093] Figure 5 Schematic diagram of the process of longitudinal and transverse deformation of a circle, where a is longitudinal deformation and b is transverse deformation; Figure 6 These are actual pictures of a circular micro-nanosphere array, a deformed triangular-shaped micro-nanosphere array, a deformed strip-shaped micro-nanosphere array, and a deformed heart-shaped micro-nanosphere array.

[0094] Combine Figure 5 and Figure 6 It can be proved that the preparation method provided by the present invention can reorganize and deform the assembled micro-nanosphere array into other shapes, which proves that the film provided by the present invention is flexible and the micro-nanosphere array on the film surface is reconfigurable.

[0095] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a microlens array, comprising the following steps: Dispersing the micro-nanospheres in a film-forming agent to obtain a dispersion; the micro-nanospheres include polystyrene micro-nanospheres, silicon dioxide micro-nanospheres, titanium dioxide micro-nanospheres or polymethyl methacrylate micro-nanospheres; Forming the dispersion into a film to obtain a water film with attached micro-nanospheres; the film formation comprises the following steps: immersing a rubber ring in the dispersion and then pulling it up to obtain a water film with attached micro-nanospheres; After the micro-nanospheres attached to the surface of the water film are assembled into an array using light pressure, a water film containing the micro-nanosphere array is obtained; The water film containing the micro-nanosphere array is transferred to the surface of a substrate to obtain the microlens array.

2. The preparation method according to claim 1, characterized in that The dispersion comprises the following steps: Mixing the micro-nanospheres and water to obtain a micro-nanosphere stock solution; The micro-nanosphere stock solution and the film-forming agent are mixed to obtain the dispersion.

3. The preparation method according to claim 1 or 2, characterized in that The average particle size of the micro-nanospheres is 2-5 μm.

4. The preparation method according to claim 2, characterized in that The mass concentration of the micro-nanosphere stock solution is 2-3%.

5. The preparation method according to claim 4, characterized in that: The volume ratio of the micro-nanosphere stock solution to the film-forming agent is 5:1800-2200.

6. The preparation method according to claim 1, characterized in that: The light source for generating the optical pressure includes a laser.

7. The preparation method according to claim 1 or 6, characterized in that: The light pressure is 0.667 to 1 pN.

8. The preparation method according to claim 1, characterized in that: The substrate includes a polydimethylsiloxane film.

9. The preparation method according to claim 1 or 8, characterized in that The transfer comprises the following steps: After the water film containing the micro-nanosphere array is suspended in the air, the substrate is penetrated from bottom to top through the water film containing the micro-nanosphere array.

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