LU502711B1

LU502711B1 - The preparation method of adaptive lens based on PDMS gel

Info

Publication number: LU502711B1
Application number: LU502711A
Authority: LU
Inventors: Li Xu; Liping Wang; Xiahui Wang; Qinghua Chen
Original assignee: Univ Zhaoqing
Priority date: 2022-08-25
Filing date: 2022-08-25
Publication date: 2023-02-27

Abstract

The present invention provides the preparation method of adaptive lens based on PDMS gel. The adaptive lens based on PDMS gel comprises PDMS gel and an actuator. The actuator changes the curvature radius of PDMS gel to realize zooming; the PDMS gel is obtained by mixing PDMS prepolymer and curing agent at the weight ratio of 50-80: 1, and heating for curing. In the technical scheme of the present invention, PDMS gel is adopted as the lens material, which has the material property between liquid and elastic film. It has the advantages of large tunable range of focal length, optical isotropy, good imaging effect, high light transmittance, good mechanical stability, easy miniaturization and integration, etc. In addition, the preparation process is simple, and the raw materials are low in lost and easy to obtain.

Description

Description LU502711

The preparation method of adaptive lens based on PDMS gel

Technical field

The present invention relates to the field of optical technical components, in particular to a preparation method of adaptive lens based on PDMS (Polydimethylsiloxane) gel.

Background

With the progress and development of science and technology, the volume of optical system is gradually developing towards miniaturization and integration, and the requirement for performance stability is also gradually improved. The traditional optical imaging system combines a series of optical glass lenses, and then the mechanical moving parts drive the distance among them to adjust the focal length. Therefore, the volume is large for this method, which can't meet the requirements of fine and small optical system.

Adaptive lens can overcome the shortcomings of glass lens, can zoom automatically, simplify the structure, and is conducive to miniaturization and integration of devices. It is the main direction of lens development in the future. At present, the most widely reported adaptive lens is liquid crystal or liquid lens. However, due to the problems of liquid crystal itself, such as slow response, light scattering, polarization correlation and so on, it is very difficult to make a liquid crystal adaptive lens with high optical performance, and it is difficult to adjust the focal length by a large range. Liquid lenses are also faced with several challenges such as complex manufacturing, huge structure and mechanical instability. Therefore, it is urgent to develop an adaptive lens that can not only avoid the light scattering and polarization problems of liquid crystal materials, but also solve the mechanical instability caused by the gravity effect of liquid materials.

Summary

In view of the above technical problems, the present invention discloses a preparation method of the adaptive lens based on PDMS gel, which solves the bottleneck problems of existing lenses such as polarization-related defects, mechanical instability, slow response speed, complex device structure, etc., and realizes the optical isotropy of the lens. It is easy to manufacture, good in mechanical stability, low in cost 502741 high in optical performance, wide in adjustable range of focal length and easy to miniaturize and integrated.

Therefore, the technical scheme adopted by the present invention is as follows:

The adaptive lens based on PDMS gel comprises PDMS gel and an actuator. The actuator changes the curvature radius of PDMS gel to realize zooming;

The PDMS gel is obtained by mixing PDMS prepolymer and curing agent at the weight ratio of 50-80:1, then heating for curing.

For the PDMS gel of the technical scheme of the present invention, PDMS prepolymer and curing agent are mixed at the weight ratio of 50-80:1, and the PDMS gel obtained by curing in this ratio range is in a gel state between liquid and solid, so that the obtained polymer PDMS material is soft and elastic, and the curvature radius is changed under the drive of an actuator (such as mechanical pressure, piezoelectric effect, thermal effect, electromagnetic pressure or fluid pressure), thereby the refraction ability of the lens can be changed to adjust the focus length. This lens is different from the

PDMS elastic film used in present, which has the disadvantages of liquid leakage, mechanical instability, small focal length variation range, large distortion and poor imaging quality. Specifically, there are two kinds of existing similar lenses, one is a liquid lens based on PDMS elastic film, which has a wide zoom range, but it is easy to leak liquid and affect by gravity, and it produces electromagnetic interference, slow response speed, relatively large volume and too high driving voltage when it is driven by magnetic force; the other one is a solid lens based on PDMS elastomer. The PDMS lens which can be produced by jet printing or 3D printing technology, has a fixed focal length, while the variable focus solid lens driven by mechanical pressure and thermal effect has a small focal length variation range, large shape distortion and poor imaging quality.

As a further improvement of the present invention, the driving mechanism is in the form of mechanical pressure, piezoelectric effect, thermal effect, electromagnetic pressure or fluid pressure.

As a further improvement of the present invention, the adaptive lens based on

PDMS gel comprises an iris diaphragm and an optical substrate. The base plate of the iris diaphragm is hermetically connected with the optical substrate, and then a cavity 1$1502711 formed, at last, PDMS gel is arranged in the cavity.

Using this method, when driving the iris diaphragm handle, the blades of the iris diaphragm change while the aperture in the middle changes, then cause the change of the shape of PDMS gel located in it, and the focal length of the lens also changes with the convex degree of the gel surface profile. As a further improvement of the present invention, the first PDMS gel is arranged in the cavity, and the blade of the iris diaphragm is covered with a gel film prepared from the second PDMS gel. The weight ratio of PDMS prepolymer to curing agent prepared for the first PDMS gel is higher than that for the second PDMS gel, and the second gel film covers the surface of the first PDMS gel.

As a further improvement of the present invention, the thickness of the gel film is 10-200um.

As a further improvement of the present invention, the weight ratio of PDMS prepolymer to curing agent for the first PDMS gel is 70-80:1, and that of PDMS prepolymer to curing agent for the second PDMS gel is 50-60:1.

As a further improvement of the present invention, the first PDMS gel is heated and cured at 90-110°C for 1~3h.

As a further improvement of the present invention, the gel film is obtained by spin coating and then heating for curing; the rotation speed of spin coater is 200~700rpm, and the time is 3~8s. Further, preferably, the rotation speed of the spin coater is 500rpm and the time is 5s.

As a further improvement of the present invention, the second PDMS gel is heated and cured at 90~110°C for 0.5-2h.

As a further improvement of the present invention, the PDMS prepolymer is

SYLGARD 184 of Dow Corning Company.

The present invention also discloses a preparation method of the adaptive lens based on PDMS gel, it comprises the following steps:

S1. Mixing PDMS prepolymer and curing agent at two weight ratios respectively, then pouring into a clean and dried container, uniformly stirring, and vacuuming to remove bubbles to obtain the first PDMS gel and the second PDMS gel, wherein the weight ratio of PDMS prepolymer to curing agent for preparing the first PDMS gel 1$1502711 higher than that for preparing the second PDMS gel;

S2. Selecting an iris diaphragm as the pressure drive of the adaptive lens, selecting a clean optical substrate, placing one side of the iris diaphragm base plate on the optical substrate, and packaging at the junction of the iris diaphragm base plate and the optical substrate to form a cavity between them;

S3. Adjusting the aperture of the iris diaphragm to a position with a specified size, injecting the first PDMS gel into the cavity until the cavity is full, standing to remove bubbles, then heating for curing;

S4. Coating the second PDMS gel on the surface of the iris diaphragm, and heating for curing to form a gel film.

As a further improvement of the present invention, S4 includes: adding the second

PDMS gel to the central aperture of the iris diaphragm containing the cured first PDMS gel, placing it on a spin coater for spin coating, so that the second PDMS gel covers the blades of the iris diaphragm, and then heating for curing to form a gel film.

As a further improvement of the present invention, in S1, the weight ratio of PDMS prepolymer to curing agent for the first PDMS gel is 70~80:1, and that of PDMS prepolymer to curing agent for the second PDMS gel is 50~60:1.

As a further improvement of the present invention, in S2, the temperature of heating for curing is 90~110°C and the time is 1~3h.

As a further improvement of the present invention, in S4, the rotation speed of the spin coater is 200-700rpm, the time is 3-8s, the temperature of heating for curing is 90~110°C, and the time is 0.5-2h. Further, preferably, the rotation speed of the spin coater is 500rpm and the time is 5s.

As a further improvement of the present invention, the PDMS prepolymer is

SYLGARD 184 of Dow Corning Company.

As a further improvement of the present invention, in S2, the junction between the base plate of the iris diaphragm and the optical substrate is encapsulated by UV curing with photosensitive adhesive.

As a further improvement of the present invention, the driving control of the Iris 502711 diaphragm can be in various ways, such as mechanical pressure, piezoelectric effect, thermal effect, electromagnetic pressure or fluid pressure.

Compared with the prior art, the present invention has the advantages that:

Firstly, the technical scheme of the present invention adopts PDMS gel as the lens material which is made of base resin and curing agent of PDMS at a specific ratio, and has material properties between liquid and elastic film, such as excellent transparency in the visible wavelength range, low surface roughness, high elasticity, good temperature stability and solvent resistance, etc. The lens fabricated by PDMS gel has a large tunable range of focal length, for example, a lens with an initial aperture of ~3.5mm, it has a large tunable range of focal length from infinite to ~8.6mm, it also has the advantages of optical isotropy, good imaging effect, high light transmittance, good mechanical stability, and easy to be miniaturized and integrated.

Secondly, in the technical scheme of the present invention, due to the excellent plasticity of the prepared PDMS gel, it can be made into a single or array lens, and its size can also be from millimeter to micron. Due to the high elasticity and flexibility of the prepared PDMS gel, the curvature radius of the lens can also be driven in many ways.

Thirdly, in the technical scheme of the present invention, the manufacturing process is simple, and the raw materials are low in lost and easy to obtain.

Brief Description Of The Figures

Figure 1 is the schematic structural diagram of the iris diaphragm of the adaptive lens based on PDMS gel in the present invention.

Figure 2 is the structural diagram of the adaptive lens based on PDMS gel when the handle is not driven in the embodiment of the present invention.—

Figure 3 is the schematic diagram of the structure of the adaptive lens based on

PDMS gel when the handle is driven in the embodiment of the present invention.

Figure 4 is the schematic diagram of the focal length measurement principle of the adaptive lens based on PDMS gel in the embodiment of the present invention.

Figure 5 is the graph showing the relationship between the focal length and the aperture of the adaptive lens based on PDMS gel in the embodiment of the present invention.

The figure marks include: LU502711 1- iris diaphragm, 2- optical glass substrate, 3- base plate, 4- blade, 5- handle, 6- the first PDMS gel, 7- the second PDMS gel.

Description of the present invention

The preferred embodiment of the present invention will be described in further detail below.

As shown in figures 1~3, an adaptive lens based on PDMS gel includes an iris diaphragm 1 and an optical glass substrate 2. The iris diaphragm 1 includes a base plate 3, blades 4 and a handle 5. The blades 4 are connected with the handle 5, and a variable aperture is formed in the middle of the blades 4. The handle 5 is driven to change the diameter of the aperture in the middle of the blades 4. The base plate 3 of the iris diaphragm 1 is hermetically connected with the optical glass substrate 2, and a cavity is formed between the base plate 3 of the iris diaphragm 1 and the optical glass substrate 2. The first PDMS gel 6 is arranged in the cavity, a layer of gel film is covered on the blade 4 of the iris diaphragm 1, and the gel film is prepared by using the second PDMS gel 7. The weight ratio of PDMS prepolymer to curing agent for preparing the first PDMS gel 6 is higher than that for preparing the second PDMS gel 7; the gel film covers the surface of the first PDMS gel 6, and its thickness is 10-200 u m. The weight ratio of

PDMS prepolymer to curing agent for the first PDMS gel 6 is 70~80: 1, and that for the second PDMS gel 7 is 50~60: 1.

The following specific examples will be described in detail. The preparation method of the adaptive lens based on PDMS gel includes the following steps: (1) Preparing PDMS gel. a. Mixing the base resin and curing agent of PDMS polymer material (SYLGARD 184 of Dow Corning company) at the weight ratio of 80:1 and 50:1, respectively, to prepare the first PDMS gel, namely PDMS-1, and the second PDMS gel, namely

PDMS-2, then pouring into two reagent bottles which are cleaned by alcohol and deionized water and dried. b. Stirring well, vacuuming for 10 min to remove bubbles, and then standing for later use. (2) Selecting the driving mode of the lens to prepare the adaptive lens.

a. As shown in Figure 1, selecting the iris diaphragm 1 with appropriate size as tne,502741 pressure drive of the adaptive lens. Selecting the iris diaphragm 1 (Edmund Optics

Company) as shown in Figure 1 as the pressure drive of the adaptive lens. The iris diaphragm 1 consists of a handle 5, a base plate 3 and blades 4. The blade 4 has two pins on both sides and they are fixed on the outside or inside of the peripheral frame.

Ten rotatable metal blades 4 overlap each other to form a variable aperture. When the handle 5 is rotated clockwise (or counterclockwise), the central opening of the iris diaphragm 1, that is, the central aperture size, is changed by the control lever accordingly. The iris diaphragm 1 has an outer diameter of 20mm and a thickness of 5mm, and the aperture can be adjusted from 12mm to 0.5mm. b. Selecting an optical glass substrate with appropriate size, cleaning the silicon wafer with acetone, alcohol and deionized water respectively, and then blowing to dryness with nitrogen. The optical glass substrate of this embodiment is 2x2cm, with a thickness of 0.7 mm. c. Placing one side of the iris diaphragm base plate on the cleaned optical glass substrate, and then performing ultraviolet curing and packaging with photosensitive glue at the junction of the iris diaphragm base plate and the glass substrate, so that the iris diaphragm base plate and the glass substrate form a cavity, with the diameter of 12mm and the height of 3mm. The aperture of the iris diaphragm is set to ~ 3.55mm. d. Adjusting the aperture of the iris diaphragm to the specified size. e. Injecting the prepared PDMS-1 mixed solution into the cavity until the cavity is full, and then standing to remove a small amount of bubbles. f. Horizontally baking in a dryer at 100°C for 2h in order to cure and crosslink the polymer. g. After curing, in order to make the lens have excellent imaging effect and good stability, dip a small amount of PDMS-2 mixture with a clean glass rod, add it to the central aperture of the iris diaphragm, set the spin coater at a low speed of 500rpm/min for 5 s, and bake it horizontally in a dryer at 100°C for 1 h for curing after spin coating, so that PDMS-2 is covered with a thin layer of the gel film (thickness: 100 4 m) with higher hardness on the iris diaphragm blades, thus forming PDMS gel lens.

The reason why human beings can easily see objects at different distances is that 502711 ciliary muscles in human eyes change the curvature of lens, thus changing the focal length of human visual system. Inspired by human eye biomechanics and auto-focusing function, the inventor designed an adaptive lens system based on PDMS gel of iris diaphragm. The elastic lens of human eye contracts or expands through ciliary muscle and suspensory ligament. Similar to the mechanism of human eye, PDMS gel lens contracts or expands by driving the blade of iris diaphragm that function like human muscles. The cross-sectional structure of the lens is shown in Figure 2 and Figure 3. In the state of no applied pressure, PDMS-2 forms a thin gel film on the blades of the iris diaphragm at the central opening area of the iris diaphragm, so the surface profile of the gel is "flat" at the central aperture, and the focal length at this time is infinite. PDMS-2 can encapsulate PDMS-1 and reduce the gravity effect. In the expanded state, the aperture of the iris diaphragm in the central opening area is large, and the aperture is ~3.55mm; PDMS gel lens has a long focal length, as shown in Figure 2. When the handle of the iris diaphragm is rotated counterclockwise, the aperture of iris at the central opening is gradually reduced. Due to the fixed volume and the elasticity of the PDMS gel, the PDMS gel in the central area of the iris diaphragm shrinks and accordingly the surface profile of the gel changes from "flat" to "convex", at this time, it has a lens effect and the focal length gradually decreases, as shown in Figure 3. To sum up, the focal length of the lens changes with the convex degree of the gel surface profile caused by the aperture change of the iris diaphragm.

The experimental device shown in Figure 4 is used to measure the focal lengths of lens with different apertures, and the PDMS gel lens prepared in this embodiment is installed on a linear measuring table. The He-Ne laser beam (A=0.633um) is collimated and expanded by lens -1 and lens -2. The light beam is used as the incident light source of PDMS gel lens. After passing through PDMS gel lens, the light beam converges. A

CCD (SBIG ST-2000XM) is used to receive and analyze the light intensity at the focal point, so as to obtain the relationship curve between the focal length of PDMS gel lens and the aperture size. As Figure 5 shows, when the aperture of iris diaphragm is reduced from 3.55mm to 3.02mm, the focal length of PDMS gel lens changes from infinity to ~8.6mm. The result shows that the focal length changes in a large range.

Comparative example LU502711 (1) Properties of PDMS materials with different ratios of base resin and curing agent

Mixing the base resin and curing agent of PDMS polymer material (SYLGARD 184 of Dow Corning Company) at the conventional ratio reported at present, that is, mixing the base resin and curing agent at the weight ratio of 10:1, 20:1 and 30:1. After stirring evenly, separately dripping them on three identical optical glass substrates with a thickness of 0.7mm, then placing on a spin coater, spinning at 500r/min for 10 s, vacuuming for 10 min to remove bubbles, and finally baking them in a dryer at 100°C for 1 h for curing.

After curing, PDMS materials with the three ratios are all elastic films, and their elastic moduli are 2.9683, 1.8245 and 1.1654, respectively. A large number of reports and experiments have proved that with the increase of the ratio of base resin to curing agent, the elastic modulus gradually decreases, the elasticity gradually increases and the hardness gradually decreases. However, the ratio of base resin to curing agent of

PDMS used in the present invention is 50: 1 and 80: 1, and the PDMS material made by it is in a gel state between liquid and solid. This is because with the increase of the ratio of base resin to curing agent of PDMS, the two components of PDMS can't completely polymerize, and the final polymer PDMS material becomes softer and more elastic. If the ratio of base resin to curing agent is more than 100:1, its fluidity is strengthened and its stability is reduced. (2) Liquid lens based on PDMS elastic film

There are many kinds of liquid lenses using elastic film, such as pneumatic drive and electromagnetic drive, but their principle is to drive PDMS elastic film to deform, so the main lens preparation processes all include the preparation process of PDMS elastic film.

Generally, spin coating method is used to prepare PDMS elastic film for liquid lens.

The spin coating method is that, firstly, the PDMS liquid mixture, which is fully mixed and bubbles removed, is poured on the glass or silicon substrate, and then evenly coated on the substrate by the centrifugal force generated by the high-speed operation of the spin coater. The method can accurately control the thickness of the PDMS film by adjusting the rotation speed and rotation time of the spin coater. However, because when fabricating PDMS elastic film of the liquid lenses, in order to obtain a large range of focal 502711 length change and reduce the driving force, the elastic film is generally micron-sized.

Since it is tightly bonded with the substrate after curing due to the strong adhesion of

PDMS itself, if the PDMS film is thin, then it is easy to damage if directly removed. In addition, this method can't make PDMS film with graphics, and the spin-coating process is wasteful and costly.

In addition, the liquid variable focus microlens has the advantage of wide zoom range, but it is easy to leak liquid and affect by gravity, and it produces electromagnetic interference, slow response speed, relatively large volume and too high driving voltage when it is driven by magnetic force. (3) Solid lens based on PDMS elastic film a. For the preparation of solid lens based on PDMS elastic film, there are molding method, 3D printing method or jet printing method reported at present.

In the molding method, which is using the principle of reverse molding, it uses

PDMS as the material and copy the pattern on the expensive or complex holotype, so as to realize the low-cost and mass production of products. Its main advantages are that

PDMS thin films with patterns can be made, and there are no requirements for manufacturing equipment and technological conditions in the manufacturing process.

However, the manufacturing process of this method is complex, and the thickness of the manufactured film is usually in millimeter level, and the precision is not high and the cost is expensive.

In the 3D printing method, it uses PDMS as the material, and design the three-dimensional structure model of the lens, and then spray or print layer by layer in gel medium by jet printer or 3D printer to obtain the initial body of the three-dimensional structure model of the lens; After molding and curing, the lens is finally obtained.

In the printing method, it injects PDMS elastomer and curing agent into the corresponding microinjection pumps respectively, and sets the injection speed of the microinjection pumps, then adjusts the distance between the electrojet printing micro-nozzle and the printing substrate, and sets the micro-jet parameters and the motion parameters of the three-dimensional worktable in the electrojet printing process.

According to the set microjet parameters, the PDMS microdroplets are sprayed onto the printing substrate by electrojet printing micro-nozzle, and then cured to form PDMS 505711 microdroplet array.

The three kinds of lens preparation methods have complex processes, and all of the obtained PDMS elastic film solid lenses have fixed focal length, which can't realize zoom function. b. For the variable focus solid lens based on PDMS elastic film, it has reported that variable focus PDMS lens systems based on artificial iris and-PDMS microlenses based on electrostatic drive-

The zoom lens system proposed by Jong-Moon Choi includes PDMS elastic film lens, winding SMA actuator and load arm. Its artificial iris (including winding SMA actuator and load arm) is used to deform the shape of the elastic solid (PDMS) lens by stretching its aperture in the radial direction, thus changing the focal length. As the

PDMS elastic film with the base resin and curing agent at the weight ratio of 10:1 is used as the lens, the hardness of this kind of PDMS elastic film is high, so the shape change is usually accompanied by large shape distortion, which leads to large image distortion, reduces the optical performance of the lens, and the adjustable range of focal length is small. In addition, its structure is complex, and it can't be miniaturized.

For all-solid-state variable focus microlens based on PDMS film drived by electrostatic, the PDMS polymer with the weight ratio of prepolymer to curing agent of 20: 1 is placed between two glass layers with different thicknesses and containing annular electrode actuators. When a voltage is applied to the electrodes, the coulomb force generated between the electrodes forces the glass film to bend, thus it forms a lens structure. Different voltages will make the glass film have different bending curvatures, thus changing the focal length of the microlens. PDMS lens with this structure also faces the problems of complex manufacturing process, small change of focal length and image distortion.

Therefore, it can be seen from the above comparison that the physical properties of

PDMS materials with different ratios of base resin to curing agent are different. In the embodiment of the present invention, PDMS gel, a lens material, is prepared by adopting a specific ratio of base resin to curing agent of PDMS, which has material properties between liquid and elastic film, and excellent transparency in the visible wavelength range, low surface roughness, high elasticity and good mechanical stability. The 500711 technical scheme of the present invention solves the bottleneck problems of polarization, mechanical instability, slow response speed, complex device structure and so on, and realizes the characteristics of optical isotropy, high optical performance, large adjustable range of focal length, easy manufacture, good mechanical stability, low cost, easy miniaturization and integration, etc. These characteristics are one of the frontier development directions of adaptive lens devices at present, which can be used as an important technical basis for building the next generation of new adaptive lenses with higher performance and lower power consumption, and open up a new perspective for imaging and display, especially for the development of switchable 2D/3D display and flexible display devices.

The existing lens made of PDMS elastic film has high hardness, and when used as lens material, the deformation is large, so the imaging quality is poor. In the technical scheme of the present invention, PDMS gel with high elasticity and good mechanical stability is adopted, and the adaptive lens based on the PDMS gel with the novel ratio greatly improves the imaging quality and other optical properties of the lens. In addition, compared with PDMS elastic film lens, the lens based on PDMS gel material has simple production process, no need of complex demoulding process, lower cost, larger range of focal length variation, better imaging quality, and easier miniaturization and integration.

The above is a further detailed description of the present invention combined with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is only limited to these descriptions. For ordinary technicians in the technical field which the present invention belongs to, on the premise of not departing from the concept of the present invention, a number of simple deductions or substitutions can be made, all of them should be regarded as belonging to the protection scope of the present invention.

Claims

1. An adaptive lens based on PDMS gel is characterized in that it comprises PDMS gel and an actuator, the actuator changes the curvature radius of PDMS gel to realize zooming; the PDMS gel is obtained by mixing PDMS prepolymer and curing agent at the weight ratio of 50-80: 1, and heating for curing; it comprises an iris diaphragm and an optical substrate, the base plate of the iris diaphragm is hermetically connected with the optical substrate, a cavity is formed between the base plate of the iris diaphragm and the optical substrate, and PDMS gel is located in the cavity; the cavity is provided with the first PDMS gel, and the blade of the iris diaphragm is covered with a gel film which is prepared from the second PDMS gel, and the weight ratio of PDMS prepolymer to curing agent for the first PDMS gel is higher than that for the second PDMS gel, and the gel film covers the surface of the first PDMS gel; the weight ratio of PDMS prepolymer to curing agent for the first PDMS gel is 70~80: 1, and that of PDMS prepolymer to curing agent for the second PDMS gel is 50~60: 1; the adaptive lens based on PDMS gel is prepared by the following steps:

S1. mixing PDMS prepolymer and curing agent at two weight ratios respectively, then pouring into a clean and dried container, uniformly stirring, and vacuuming to remove bubbles to obtain the first PDMS gel and the second PDMS gel, wherein the weight ratio of PDMS prepolymer to curing agent for preparing the first PDMS gel is higher than that for preparing the second PDMS gel;

S3. adjusting the aperture of the iris diaphragm to a position with a specified size, injecting the first PDMS gel into the cavity until the cavity is full, standing to remove bubbles, and heating for curing; The first PDMS gel is heated and cured at 90~110°C for 1~3h;

S4. coating the second PDMS gel on the surface of the iris diaphragm, and heating, 502741 for curing to form a gel film; the gel film is obtained by spin coating the gel on a spin coater, and then heating for curing; The rotation speed of spin coater is 200-700rpm/min, the time is 3-8s; the temperature of heating for curing is 90~110°C, and the time is

0.5-2h.

2. The adaptive lens based on PDMS gel according to claim 1 is characterized in that the driving mechanism is in the form of mechanical pressure, piezoelectric effect, thermal effect, electromagnetic pressure or fluid pressure.

3. The adaptive lens based on PDMS gel according to claim 1 is characterized in that the thickness of the gel film is 10~200um, the PDMS prepolymer is SYLGARD 184 from Dow Corning Company.

4. The preparation method of adaptive lens based on PDMS gel according to claim 1 is characterized in that it comprises the following steps:

S2. selecting an iris diaphragm as the pressure drive of the self-adaptive lens, selecting a clean optical substrate, placing one side of the iris diaphragm base plate on the optical substrate, and packaging at the junction of the iris diaphragm base plate and the optical substrate to form a cavity between them;

S3. adjusting the aperture of the iris diaphragm to a position with a specified size, injecting the first PDMS gel into the cavity until the cavity is full, standing to remove bubbles, and heating for curing;

5. The preparation method of the self-adaptive lens based on PDMS gel according to claim 4 is characterized in that S4 comprises: adding the second PDMS gel to the central aperture of the iris diaphragm containing the cured first PDMS gel, placing it on a spin coater for spin coating, so that the second PDMS gel covers the blades of the Ils 502711 diaphragm, and then heating for curing to form a gel film.

6. The preparation method of adaptive lens based on PDMS gel according to claim is characterized in that: in S1, the weight ratio of PDMS prepolymer to curing agent for preparing the first PDMS gel is 70-80: 1, and that of PDMS prepolymer to curing agent for preparing the second PDMS gel is 50-60: 1; in S2, heating for curing at 90~110°C for 1~3h; in S4, the rotation speed of the spin coater is 200-700rpm/min and the time is 3-8s, and the temperature of heating for curing is 90~110°C and the time is 0.5-2h.