阅读说明：本技术 一种微透镜阵列光栅及其制备方法和应用 (Micro-lens array grating and preparation method and application thereof ) 是由 金建 邸思 王旭迪 孙学通 于 2021-08-11 设计创作，主要内容包括：本发明涉及光学技术领域,具体涉及一种微透镜阵列光栅及其制备方法和应用。所述微透镜阵列光栅的制备方法为采用具有气孔阵列的微流控芯片,利用水压将PDMS光栅变形为微透镜阵列光栅。本发明采用微流控技术制作微透镜阵列光栅上,解决了传统工艺制作微透镜阵列光栅时存在的集成度不高以及工艺不可控等问题。本制备的微透镜阵列光栅元件,组合了聚焦和色散两种功能,相比传统元件,降低了元件的尺寸和成本；微透镜阵列光栅可以在同一个基片上集成不同尺寸的微透镜,使其同时具有不同的分光功能,提高了元件的集成度。(The invention relates to the technical field of optics, in particular to a micro-lens array grating and a preparation method and application thereof. The preparation method of the micro-lens array grating adopts a micro-fluidic chip with an air hole array, and the PDMS grating is deformed into the micro-lens array grating by using water pressure. The invention adopts the microfluidic technology to manufacture the microlens array grating, and solves the problems of low integration level, uncontrollable process and the like when the microlens array grating is manufactured by the traditional process. The prepared microlens array grating element combines two functions of focusing and dispersion, and compared with the traditional element, the size and the cost of the element are reduced; the micro lens array grating can integrate micro lenses with different sizes on the same substrate, so that the micro lens array grating has different light splitting functions, and the integration level of elements is improved.)

1. A preparation method of a micro-lens array grating is characterized in that a micro-fluidic chip with an air hole array is adopted, and a PDMS grating is deformed into the micro-lens array grating by utilizing water pressure.

2. The method for preparing a microlens array grating according to claim 1, wherein the method for preparing the PDMS grating comprises: firstly, manufacturing an original grating template; pouring the PDMS solution I on the original grating template, and heating and curing; the PDMS solution I is a mixed solution of polydimethylsiloxane and a curing agent, and the ratio of the polydimethylsiloxane to the curing agent is 15-20: 1.

3. The method for manufacturing a microlens array grating as claimed in claim 1, wherein the microfluidic chip having the air hole array includes a top layer, a middle microfluidic channel layer, and a lower support layer; the top layer is provided with a microfluidic outlet, a microfluidic inlet and an air hole array; the middle micro-flow channel layer is a PDMS micro-flow channel layer.

4. The method for manufacturing a microlens array grating according to claim 3, wherein the microfluidic chip having the air hole array is manufactured by the following method:

step 1: taking two pieces of organic glass, and engraving a microfluidic outlet, a microfluidic inlet and an air hole array on one of the two pieces of organic glass in a laser drilling mode to form a top layer; the other piece of organic glass is used as a lower supporting layer;

step 2: machining the organic glass by adopting a CNC (computerized numerical control) precision numerical control machine tool to prepare a micro-channel template; pouring the PDMS solution II on the micro-channel template to copy a pattern, and then demolding to obtain a PDMS micro-channel layer;

and step 3: and permanently bonding the top layer, the PDMS micro-flow channel layer and the lower support layer by adopting a peroxide ion bombardment bonding technology.

5. The method for preparing a microlens array grating as in claim 4, wherein the PDMS solution II in the step 2 is a mixed solution of polydimethylsiloxane and a curing agent, and the ratio of the polydimethylsiloxane to the curing agent is 10: 1.

6. The method for preparing a microlens array grating according to claim 5, wherein the specific way of deforming the PDMS grating into the microlens array grating by using water pressure is as follows:

step S1: bonding a PDMS block above a microfluidic outlet and a microfluidic inlet on the top layer of the microfluidic chip with the air hole array, and arranging a water outlet pipe outlet and a water pipe inlet on the PDMS block; the inlet of the water pipe is communicated with the microfluidic inlet and is used for injecting water into the microfluidic chip; the outlet of the water pipe is communicated with the microfluidic outlet, and the outlet of the water pipe is connected with a pressure tester which is used for controlling water pressure;

step S2: bonding the PDMS grating with the microfluidic chip connected in the step S1;

step S3: and injecting water into the microfluidic chip through a water pipe inlet, controlling the water pressure by using a water pressure tester, and deforming the PDMS grating into the micro-lens array grating through the water pressure.

7. The method of claim 6, further comprising pouring a PUA solution on the microlens array grating, and curing the PUA solution by UV to obtain the PUA microlens array grating.

8. The method of claim 7, further comprising using the PUA microlens array grating as a template to continue fabricating the PDMS microlens array grating.

9. A microlens array grating prepared by the method for preparing a microlens array grating according to any one of claims 1 to 8.

10. A method for preparing a microlens array grating according to any one of claims 1 to 8 or a use of the microlens array grating according to claim 9 in the field of optical technology.

Technical Field

The invention relates to the technical field of optics, in particular to a micro-lens array grating and a preparation method and application thereof.

Background

Spectrometers (spectroscopes) are scientific instruments that decompose light of complex composition into spectral lines and have important and widespread applications in fields such as agriculture, astronomy, automotive, biology, chemistry, environmental detection, food, medicine, etc. The separate optical components in the spectrometer, such as the curved collimating collector mirror and the typical diffraction grating, complicate the spectrometer structure and increase the manufacturing cost of the spectrometer.

In order to reduce the size and cost of the optical elements in a spectrometer, it is desirable to minimize the number of optical elements by combining different optical functions into one element. In conventional spectrometer systems, the two main optical functions are focusing and dispersion, which can be combined by making a diffractive surface on a refractive or reflective optical element. Such as curved gratings, grating-fresnel lenses, and grating-microlens hybrid elements. The micro lens array grating mixing element integrates two optical functions of focusing and dispersion, and has the advantages of realizing different light splitting effects on the same element, realizing light splitting of light beams in a large area and the like.

At present, there are many processing methods for manufacturing microlens array elements or grating elements. However, the prior art has not been well processed to combine microlens arrays with grating structures. The common processing technology at present is to combine the microlens array and the grating structure in a splicing manner, however, the matching problem between the two optical elements inevitably exists in such processing technology, and the integration level is also low. Furthermore, JunShi et al, propose a method of fabricating microlens array gratings by combining hot melt, self-assembly and replication (J.Shi, Y.Huang, L.Peng, et al, "Grating/micro array systematic by hot-melt-scaling, self-assembly and replication," Optical Materials,2020,04:109733), however, it is difficult to regulate Grating line density and microlens size by this method, and the application of the microlens array gratings fabricated thereby is limited.

Disclosure of Invention

In view of the above, it is desirable to provide a microlens array grating, a method for manufacturing the same, and applications of the microlens array grating. By combining the micro-lens array and the grating structure by adopting the micro-fluidic chip technology, the problems of low integration level, uncontrollable process and the like in the prior art when the micro-lens array grating is manufactured are solved. Furthermore, the prepared microlens array grating is used in a spectrometer, so that the size and the cost of the spectrometer can be reduced.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a method for manufacturing a microlens array grating, comprising: and (3) deforming the PDMS (polydimethylsiloxane) grating into a micro-lens array grating by using a micro-fluidic chip with an air hole array and using water pressure.

Further, in the above method for preparing a microlens array grating, the method for preparing a PDMS grating includes: firstly, manufacturing an original grating template; and pouring the PDMS solution onto the original grating template, and heating for curing.

Further, in the preparation method of the microlens array grating, the PDMS solution I is a mixed solution of polydimethylsiloxane and a curing agent, and the ratio of the polydimethylsiloxane to the curing agent is 15-20: 1.

Further, in the above method for manufacturing a microlens array grating, the microfluidic chip having the air hole array includes a top layer, a middle microfluidic channel layer, and a lower support layer; the top layer is provided with a microfluidic outlet, a microfluidic inlet and an air hole array; the middle micro-flow channel layer is a PDMS micro-flow channel layer.

Further, in the above method for manufacturing a microlens array grating, the top layer and the lower support layer are made of organic glass.

Further, in the above method for manufacturing a microlens array grating, the diameters of the air holes of different arrays may be the same or different.

Further, in the above method for manufacturing a microlens array grating, the microfluidic chip having the air hole array is manufactured by the following method:

step 1: taking two pieces of organic glass, and engraving a microfluidic outlet, a microfluidic inlet and an air hole array on one of the two pieces of organic glass in a laser drilling mode to form a top layer; the other piece of organic glass is used as a lower supporting layer;

step 2: machining the organic glass by adopting a CNC (computerized numerical control) precision numerical control machine tool to prepare a micro-channel template; pouring the PDMS solution II on the micro-channel template to copy a pattern, and then demolding to obtain a PDMS micro-channel layer;

and step 3: and permanently bonding the top layer, the PDMS micro-flow channel layer and the lower support layer by adopting a peroxide ion bombardment bonding technology.

Further, in the preparation method of the microlens array grating, the PDMS solution two in the step 2 is a mixed solution of polydimethylsiloxane and a curing agent, and the ratio of the polydimethylsiloxane to the curing agent is 10: 1.

Further, in the above method for preparing a microlens array grating, a specific way of deforming the PDMS grating into the microlens array grating by using water pressure is as follows:

step S1: bonding a PDMS block above a microfluidic outlet and a microfluidic inlet on the top layer of the microfluidic chip with the air hole array, and arranging a water outlet pipe outlet and a water pipe inlet on the PDMS block; the inlet of the water pipe is communicated with the microfluidic inlet and is used for injecting water into the microfluidic chip; the outlet of the water pipe is communicated with the microfluidic outlet, and the outlet of the water pipe is connected with a pressure tester which is used for controlling water pressure;

step S2: bonding the PDMS grating with the microfluidic chip connected in the step S1;

step S3: and injecting water into the microfluidic chip through a water pipe inlet, controlling the water pressure by using a water pressure tester, and deforming the PDMS grating into the micro-lens array grating through the water pressure.

Further, in the preparation method of the microlens array grating, a polyurethane acrylate (PUA) solution is poured on the microlens array grating, and the PUA microlens array grating is obtained after ultraviolet curing.

Further, in the preparation method of the microlens array grating, the method further comprises the step of continuously manufacturing the PDMS microlens array grating by taking the PUA microlens array grating as a template.

In a second aspect, the invention provides a microlens array grating, which is prepared by the above preparation method.

In a third aspect, the present invention provides an application of the microlens array grating or the method for manufacturing the microlens array grating in the field of optical technology, including but not limited to a spectrometer.

The invention has the beneficial effects that:

the invention adopts the microfluidic technology to manufacture the microlens array grating, and solves the problems of low integration level, uncontrollable process and the like when the microlens array grating is manufactured by the traditional process.

And secondly, the microlens array grating element prepared by the invention combines two functions of focusing and dispersion, and reduces the size and cost of the element compared with the traditional element. In addition, the microlens array grating of the invention can integrate microlenses with different sizes on the same substrate, so that the microlens array grating has different light splitting functions, thereby improving the integration level of elements.

And thirdly, after the PDMS micro lens array grating is prepared, the PUA solution is used as a record to prepare the PUA micro lens array grating. The PUA microlens array grating has long storage time and can be repeatedly used, and can be used as a template to continue the batch production of the microlens array grating.

Drawings

FIG. 1 is a schematic diagram of an original grating template structure prepared according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a process for fabricating a PDMS grating template according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a PDMS grating template prepared according to an embodiment of the present invention;

FIG. 4 is an exploded view of a microfluidic chip with a porous array according to an embodiment of the present invention, FIG. 4a is a top layer of the microfluidic chip, FIG. 4b is a middle channel layer of the microfluidic chip, and FIG. 4c is a lower support layer of the microfluidic chip;

FIG. 5 is a schematic structural diagram of a bonded microfluidic chip according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of an embodiment of the present invention in which a PDMS grating is transformed into a microlens array grating by water pressure;

FIG. 7 is a schematic diagram of an embodiment of the present invention, in which a PDMS microlens array grating is used as a template to prepare a PUA microlens curved grating.

Reference numerals: the method comprises the following steps of 1-quartz glass substrate, 2-photoresist grating, 3-mold box, 4-PDMS solution I, 5-PDMS grating template, 6-PDMS block, 7-water pipe inlet, 8-water pipe outlet, 9-pressure tester, 10-PDMS micro lens array grating and 11-PUA micro lens array grating.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be further clearly and completely described below with reference to the embodiments of the present invention. It should be noted that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

PDMS used in the examples of the present invention was a silicone rubber of type sylgard 184, manufactured by Dow Corning, USA.

The curing agent used in the examples of the present invention may be any one conventionally selected by those skilled in the art and commercially available, and the present invention is not particularly limited.

Example 1

A method for preparing a microlens array grating comprises the following steps: and (3) deforming the PDMS grating into a micro lens array grating by using a micro-fluidic chip with an air hole array and using water pressure. The method specifically comprises the following steps:

preparing a PDMS grating: firstly, manufacturing an original grating template; the original grating template is prepared by conventional methods of those skilled in the art, including but not limited to holographic lithography, electron beam lithography ion etching, wet etching, and the like. This embodiment is exemplified by a reticle exposure method.

Preparing an original grating template:

substrate treatment: a piece of quartz glass with a flat surface was taken as a quartz glass substrate 1 (the thickness of the glass sheet in this example was 2mm), and the quartz glass substrate 1 was washed with water and acetone, and then placed in an oven and baked at 130 ℃ for 20 minutes to remove moisture and residual acetone. Naturally cooling, and ashing in an ashing machine for one hour to enhance the surface adhesion and prevent degumming in the subsequent developing process;

preparing photoresist: the photoresist model used in this example is AZ5530, and the photoresist and cyclopentanone are diluted in a volume ratio of 2:1, and the diluted photoresist has a thinner photoresist layer after spin coating, which is beneficial to subsequent exposure and development. Uniformly dripping the diluted photoresist on a quartz glass substrate 1, then homogenizing the photoresist at the rotating speed of 800 revolutions per minute for 10 seconds, and then homogenizing the photoresist at the rotating speed of 1500 revolutions per minute for 40 seconds, wherein the photoresist is about 1.6 mu m thick; it was then placed in a 90 ℃ oven for 15min to remove excess solvent.

Exposure of the mask: in the embodiment, the mask is a chromium plating mask, the period is 10 mu m, and the duty ratio is 1: 1. After the chromium-plated surface of the mask is tightly attached to the photoresist, the photoresist is exposed for 55 seconds under ultraviolet, and after exposure, the quartz glass substrate is placed into NaOH solution with the mass percent of 2.5 per mill for development for 1 min; sodium hydroxide solution of too high concentration cannot be used here, otherwise it is liable to develop too quickly and degum. After the development is completed, a photoresist grating 2 with a density of 100 lines/mm, a duty cycle of 1:1 and a depth of about 1.6 μm is produced, as shown in fig. 1. And after the development is finished, washing with deionized water and drying with nitrogen, placing in a 90 ℃ oven for 20min to remove water vapor, and preventing water bubbles from being generated during the subsequent preparation of the PDMS grating.

As shown in fig. 2, the original grating template is placed in the mold box 3, and a PDMS solution one 4 is poured on the original grating template and cured by heating. The PDMS solution I is a mixed solution of polydimethylsiloxane and a curing agent, and the ratio of the polydimethylsiloxane to the curing agent is 20: 1; the heating and curing are specifically carried out by preheating for 30min at 45 ℃ on a drying table, then heating and curing for 30min at 60 ℃, and finally heating and curing for 1h at 90 ℃. The prepared PDMS grating template 5 is shown in fig. 3. In the first example of the PDMS solution, the ratio of the polydimethylsiloxane to the curing agent is 20:1, and the elasticity is optimal and the degree of deformation is maximum compared to other ratios.

(II) preparing a micro-fluidic chip with an air hole array: the micro-fluidic chip with the air hole array comprises a top layer, a middle micro-channel layer and a lower supporting layer; the top layer is provided with a microfluidic outlet, a microfluidic inlet and an air hole array; the middle micro-flow channel layer is a PDMS micro-flow channel layer; the top layer and the lower supporting layer are made of organic glass materials.

The micro-fluidic chip with the air hole array is prepared by the following method:

step 1: taking two pieces of organic glass, and engraving a microfluidic outlet, a microfluidic inlet and an air hole array on one of the pieces of organic glass by adopting a laser drilling mode to be used as a top layer, as shown in figure 4 a; another piece of plexiglass acts as the lower support layer, as shown in FIG. 4 c;

step 2: machining the organic glass by adopting a CNC (computerized numerical control) precision numerical control machine tool to prepare a micro-channel template; pouring the PDMS solution II on the micro-channel template to copy a pattern, and then demolding to obtain a PDMS micro-channel layer, as shown in FIG. 4 b; the PDMS solution II is a mixed solution of polydimethylsiloxane and a curing agent, and the ratio of the polydimethylsiloxane to the curing agent is 10: 1;

and step 3: and permanently bonding the top layer, the PDMS micro-flow channel layer and the lower support layer by adopting a peroxide ion bombardment bonding technology. The bonded microfluidic chip with the air hole array is shown in fig. 5.

And (III) deforming the PDMS grating into a micro-lens array grating by using water pressure: as shown in fig. 6:

step S1: bonding a PDMS block 6 above a microfluidic outlet and a microfluidic inlet on the top layer of the microfluidic chip with the air hole array, and arranging a water pipe inlet 7 and a water pipe outlet 8 on the PDMS block; the water pipe inlet 7 is communicated with the microfluidic inlet and is used for injecting water into the microfluidic chip; the water pipe outlet 8 is communicated with the microfluidic outlet, the water pipe outlet 8 is connected with a pressure tester 9, and the pressure tester 9 is used for controlling water pressure;

step S2: bonding the PDMS grating with the microfluidic chip of the step S1; carrying out oxygen ion bombardment on the bonding surface of the PDMS curved surface grating and the top surface of the microfluidic chip to increase the surface energy, and then carrying out alignment, fitting and weight pressing; finally, placing the mixture in an oven at 80 ℃ to heat for 2 min;

step S3: and injecting water into the micro-channel chip through the inlet of the water pipe, controlling the water pressure by using a water pressure tester, and deforming the PDMS grating into the PDMS micro-lens array grating through the water pressure.

Example 2

As shown in fig. 7, in this embodiment, while the PDMS microlens array grating 10 prepared in example 1 is prepared, a PUA solution is used to prepare a PUA microlens curved grating 11, specifically as follows:

the PUA solution was poured onto the PDMS microlens array grating 10 of example 1, and after the PUA completely covered the grating and leveled, it was gradually exposed under an ultraviolet heat lamp to cure the PUA. The step-by-step exposure is exposure for 1min, and the step-by-step exposure is stopped for 1min, so that heat dissipation is facilitated, and if continuous exposure is adopted, bubbles are formed due to the generation of a large amount of heat, and the surface is uneven. The total exposure time for ultraviolet curing is 15 min. And after exposure is finished, separating the PUA from the PDMS to obtain the PUA microlens curved grating 11.

Example 3

In this embodiment, the PUA microlens curved surface grating prepared in embodiment 2 is used as a template, and the PDMS microlens array grating is obtained by copying again. The specific mode is as follows:

the PUA microlens array grating of example 2 was exposed to UV light for 1 hour to eliminate the difficulty of curing PDMS on the PUA template. And after exposure for 1h, putting the PUA microlens array grating into a glass vessel, dripping trimethyl chlorosilane on the periphery of the glass vessel, covering the glass vessel, naturally evaporating for 3min, and forming a film on the surface of the PUA microlens array grating, wherein the subsequent demolding treatment is facilitated after the film is formed on the surface of the microlens array grating.

And (II) placing the PUA microlens array grating into a mold box, and pouring the prepared and bubble-removed PDMS solution (PDMS and a curing agent are mixed in a ratio of 10: 1) on the PUA microlens array grating. And after the PDMS solution completely covers the PUA micro lens array grating and the liquid level is flat, preheating the substrate in an oven at 45 ℃ for 30min, heating and curing the substrate at 60 ℃ for 30min, and finally heating and curing the substrate at 90 ℃ for 1 h. After natural cooling, the cured PDMS was peeled off from the PUA. And obtaining the replicated PDMS micro-lens array grating.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.