CN112014912B

CN112014912B - Self-adaptive lens based on PDMS gel and preparation method thereof

Info

Publication number: CN112014912B
Application number: CN202011025116.2A
Authority: CN
Inventors: 王霞辉
Original assignee: Zhaoqing University
Current assignee: Guangdong Husuo Digital Information Technology Co ltd
Priority date: 2020-09-25
Filing date: 2020-09-25
Publication date: 2022-06-28
Anticipated expiration: 2040-09-25
Also published as: CN112014912A

Abstract

The invention provides a self-adaptive lens based on PDMS gel and a preparation method thereof, wherein the self-adaptive lens based on PDMS gel comprises PDMS gel and a driving mechanism, and the driving mechanism drives the curvature radius change of the PDMS gel to realize zooming; the PDMS gel is prepared by mixing a PDMS prepolymer and a curing agent according to a weight ratio of 80-50: 1, and heating and curing the mixture. The lens material of the technical scheme of the invention adopts PDMS gel, which has the material property between liquid and an elastic membrane, and the lens manufactured by the PDMS gel has the advantages of large tunable focal length range, optical isotropy, good imaging effect, high light transmittance, good mechanical stability, easy miniaturization and integration, and the like; in addition, the preparation process is simple, the cost of raw materials is low, and the raw materials are easy to obtain.

Description

Self-adaptive lens based on PDMS gel and preparation method thereof

Technical Field

The invention relates to the field of optical technical elements, in particular to a self-adaptive lens based on PDMS gel and a preparation method thereof.

Background

With the progress and development of science and technology, the volume of an optical system gradually develops towards miniaturization and integration, and the requirement of performance stability is gradually increased. The conventional optical imaging system uses a series of optical glass lenses to combine them, and then the distance between them is driven by a mechanical moving part to adjust the focal length. Therefore, this method is bulky and cannot satisfy the demand for a fine and compact optical system.

The self-adaptive zoom lens can overcome the defects of a glass lens group, can automatically zoom, simplifies the structure, is beneficial to miniaturization and integration of devices, and is the main direction of development of future lenses. The most widely reported adaptive zoom lenses are liquid crystal or liquid lenses. However, due to the problems of liquid crystal itself, such as slow response, light scattering, polarization dependence, etc., it is difficult to fabricate a liquid crystal adaptive zoom lens having high optical performance, and it is difficult to adjust the focal length significantly. Liquid lenses also face several challenges of complexity of manufacture, bulkiness of structure, mechanical instability, etc. Therefore, there is a need to develop an adaptive lens that can avoid the light scattering and polarization related problems of the liquid crystal material and solve the mechanical instability problem caused by the gravity effect of the liquid material.

Disclosure of Invention

Aiming at the technical problems, the invention discloses a PDMS (Polydimethylsiloxane) gel-based adaptive lens and a preparation method thereof, which solve the bottleneck problems of polarization correlation, mechanical instability, slow response speed, complex device structure and the like of the existing lens, realize the optical isotropy of the lens, and have the characteristics of easy manufacture, good mechanical stability, low cost, high optical performance, large focal length adjustable range, easy miniaturization and integration and the like.

In contrast, the technical scheme adopted by the invention is as follows:

the self-adaptive lens based on the PDMS gel comprises the PDMS gel and a driving mechanism, wherein the driving mechanism drives the change of the curvature radius of the PDMS gel to realize zooming;

the PDMS gel is prepared by mixing a PDMS prepolymer and a curing agent according to a weight ratio of 80-50: 1, and heating and curing the mixture.

According to the technical scheme, the PDMS gel is prepared by mixing a PDMS prepolymer and a curing agent according to a weight ratio of 80-50: 1, the PDMS gel obtained by curing in the ratio range is in a gel state between liquid and solid, the obtained high polymer PDMS material is soft and elastic, and under the driving of a driving mechanism (such as mechanical pressure, piezoelectric effect, thermal effect, electromagnetic pressure or fluid pressure), the curvature radius is changed, so that the refractive power of a lens on light is changed, and zooming is realized. The lens is different from a PDMS elastic membrane adopted in the prior art, and the lens adopting the PDMS elastic membrane at present has the defects of liquid leakage, mechanical instability or small focal length change range, large distortion, poor imaging quality and the like. Specifically, the existing similar lenses are divided into two types, one type is a liquid lens based on a PDMS elastic membrane, the zooming range is wide, but the liquid lens is easy to leak liquid and is easily influenced by gravity, electromagnetic interference can be generated when the liquid lens is magnetically driven, the response speed is slow, the volume ratio is large, and the driving voltage is too high; the other is a solid lens based on a PDMS elastomer, the PDMS lens using the jet printing or 3D printing technology has a fixed focal length, and the variable-focus solid lens driven by mechanical pressure, thermal effect and the like has a small focal length change range, large shape distortion and poor imaging quality.

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

As a further improvement of the invention, the adaptive lens based on the PDMS gel comprises an iris diaphragm and an optical substrate, wherein a base plate of the iris diaphragm is connected with the optical substrate in a sealing way, a cavity is formed between the base plate of the iris diaphragm and the optical substrate, and the PDMS gel is arranged in the cavity.

By adopting the technical scheme, the blade of the iris diaphragm is changed by driving the iris diaphragm handle, the middle aperture is also changed, meanwhile, the shape of PDMS gel in the PDMS diaphragm is changed along with the change of the shape of the PDMS gel, and the focal length of the lens is changed along with the convex degree of the surface profile of the gel caused by the change of the aperture of the iris diaphragm. As a further improvement of the present invention, a first PDMS gel is disposed in the chamber, a layer of gel film covers the blade of the variable aperture, the gel film is prepared from a second PDMS gel, a weight ratio of the PDMS prepolymer for preparing the first PDMS gel to the curing agent is higher than a weight ratio of the PDMS prepolymer for preparing the second PDMS gel to the curing agent, and the gel film covers the surface of the first PDMS gel.

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

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

As a further improvement of the invention, the temperature of the first PDMS gel is 90-110 ℃ and the time is 1-3 h.

As a further improvement of the invention, the gel film is obtained by heating and curing after glue is homogenized on a glue homogenizing machine; the rotation speed of the spin coater is 200-700 r/min, and the time is 3-8 s. Further preferably, the rotation speed of the spin coater is 500 rpm, and the time is 5 s.

As a further improvement of the invention, the temperature of the second PDMS gel for heating and curing is 90-110 ℃, and the time is 0.5-2 h.

As a further improvement of the invention, the PDMS prepolymer is SYLGARD 184 from Dow Corning.

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

step S1, mixing the PDMS prepolymer and the curing agent according to the weight ratio of the two proportions, pouring the mixture into a clean and dried container, uniformly stirring the mixture, vacuumizing the container to remove bubbles to obtain a first PDMS gel and a second PDMS gel, wherein the weight ratio of the PDMS prepolymer for preparing the first PDMS gel to the curing agent is higher than the weight ratio of the PDMS prepolymer for preparing the second PDMS gel to the curing agent;

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

step 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 of PDMS gel, standing to remove bubbles, and heating and curing;

step S4, applying a second PDMS gel to the surface of the variable aperture, and heating and curing to form a gel film.

As a further improvement of the present invention, step S4 includes: adding the second PDMS gel to the central aperture of the iris diaphragm containing the cured product of the first PDMS gel, placing the mixture on a spin coater for spin coating, covering the blades of the iris diaphragm with the second PDMS gel, and heating and curing to form a gel film.

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

As a further improvement of the invention, in step S2, the heating and curing temperature is 90-110 ℃, and the time is 1-3 h.

As a further improvement of the invention, in step S4, the rotation speed of the spin coater is 200-700 rpm, the time is 3-8S, the temperature of heating and curing is 90-110 ℃, and the time is 0.5-1.5 h. Further preferably, the rotation speed of the spin coater is 500 rpm, and the time is 5 s.

As a further improvement of the present invention, in step S2, the interface between the bottom plate of the iris diaphragm and the optical substrate is uv-cured and encapsulated by a photosensitive adhesive.

As a further improvement of the present invention, the driving control of the iris diaphragm may be performed in various manners, such as mechanical pressure, piezoelectric effect, thermal effect, electromagnetic pressure, or fluid pressure.

Compared with the prior art, the invention has the following beneficial effects:

firstly, the technical scheme of the invention adopts the lens material-PDMS gel prepared by the PDMS main agent and the curing agent according to the method of specific proportion, the PDMS gel has the material properties between liquid and an elastic membrane, such as excellent transparency, low surface roughness, high elasticity, good temperature stability, good solvent resistance and the like in the visible wavelength range, the material is manufactured into the lens, the focal length tunable range is large, such as the lens with the initial aperture of 3.5mm, the focal length tunable range is infinite to 8.6mm, and the focal length tunable range is large; and the optical imaging device has the advantages of optical isotropy, good imaging effect, high light transmittance, good mechanical stability and the like, and is easy to miniaturize and integrate.

Secondly, by adopting the technical scheme of the invention, the prepared PDMS gel has excellent plasticity, can be used as a single or array lens, and can have the size from millimeter magnitude to micrometer magnitude. Due to the high elasticity and flexibility of the PDMS gel, the curvature radius of the lens can be controlled in various ways.

Thirdly, the technical scheme of the invention has the advantages of simple manufacturing process, low cost of raw materials and easy obtainment.

Drawings

Fig. 1 is a schematic structural diagram of an iris diaphragm of an adaptive lens based on PDMS gel according to the present invention.

Fig. 2 is a schematic structural diagram of an adaptive lens based on PDMS gel when the handle is not actuated according to an embodiment of the present invention.

Fig. 3 is a schematic structural diagram of an adaptive lens based on PDMS gel when a handle is actuated according to an embodiment of the present invention.

Fig. 4 is a schematic diagram illustrating a focal length measurement principle of the PDMS gel-based adaptive lens according to an embodiment of the present invention.

FIG. 5 is a graph of the focal length of an adaptive lens based on PDMS gel as a function of aperture according to an embodiment of the present invention.

The reference numerals include:

1-iris diaphragm, 2-optical glass substrate, 3-bottom plate, 4-blade, 5-handle, 6-first PDMS gel and 7-second PDMS gel.

Detailed Description

Preferred embodiments of the present invention are described in further detail below.

As shown in fig. 1 to 3, the adaptive lens based on PDMS gel comprises an iris diaphragm 1 and an optical glass substrate 2, wherein the iris diaphragm 1 comprises a base plate 3, a blade 4 and a handle 5, the blade 4 is connected with the handle 5, a variable hole is formed in the middle of the blade 4, and the handle 5 is driven to change the hole diameter of the hole in the middle of the blade 4. The diaphragm 1 comprises a base plate 3 and an optical glass substrate 2, wherein the base plate 3 is connected with the optical glass substrate 2 in a sealing mode, a cavity is formed between the base plate 3 of the diaphragm 1 and the optical glass substrate 2, a first PDMS gel 6 is arranged in the cavity, a layer of gel film covers a blade 4 of the diaphragm 1, the gel film is prepared from a second PDMS gel 7, the weight ratio of a PDMS prepolymer for preparing the first PDMS gel 6 to a curing agent is higher than that of the PDMS prepolymer for preparing the second PDMS gel 7 to the curing agent, and the gel film covers the surface of the first PDMS gel 6. The thickness of the gel film is 10-200 μm. The weight ratio of the PDMS prepolymer for preparing the first PDMS gel 6 to the curing agent is 70-80: 1, and the weight ratio of the PDMS prepolymer for preparing the second PDMS gel 7 to the curing agent is 50-60: 1.

As will be described in detail below with reference to specific examples, the method for preparing the PDMS gel-based adaptive lens includes the following steps:

(1) PDMS gels were prepared.

a. A main agent and a curing agent of PDMS polymer material (SYLGARD 184 of Dow Corning company) are mixed according to the weight ratio of 80:1 and 50:1 respectively to prepare a first PDMS gel namely PDMS-1 and a second PDMS gel namely PDMS-2, and then the first PDMS gel and the second PDMS gel are respectively poured into two reagent bottles which are cleaned by alcohol and deionized water and are dried.

b. Stirring evenly, vacuumizing for 10 minutes to remove bubbles, and then standing for later use.

(2) And selecting a lens driving mode to prepare the self-adaptive lens.

a. As shown in fig. 1, an appropriately sized iris diaphragm 1 is selected as the pressure drive of the adaptive lens. An iris diaphragm 1 (Edmund Optics) as shown in fig. 1 was chosen as the pressure drive for the adaptive lens. The iris diaphragm 1 is composed of a handle 5, a base plate 3, and blades 4. The blade 4 has two pins on both sides, which are fixed on the outside or inside of the perimeter frame. Ten rotatable metal blades 4 are overlapped with each other to be combined into a variable aperture. By rotating the handle 5 in a clockwise (or counter-clockwise) direction, the central opening, i.e. the central aperture size, of the iris diaphragm 1 will be changed accordingly by means of the control rod. The iris diaphragm 1 has an outer diameter of 20mm and a thickness of 5mm, and the aperture can be adjusted from 12mm to 0.5 mm.

b. Selecting an optical glass substrate with a proper size, respectively cleaning a silicon wafer by using acetone, alcohol and deionized water, and then drying by using nitrogen. The optical glass substrate of this example was a 2X 2cm optical glass substrate having a thickness of 0.7 mm.

c. One side of the iris diaphragm base plate is placed on the cleaned optical glass substrate, and then ultraviolet curing packaging is carried out on the boundary of the iris diaphragm base plate and the glass substrate by using photosensitive adhesive, so that the iris diaphragm base plate and the glass substrate form a cavity. The chamber has a diameter of 12mm and a height of 3 mm. The aperture of the iris diaphragm is set to be 3.55 mm.

d. The aperture of the iris diaphragm is adjusted to a position of a prescribed size.

e. And then injecting the prepared mixed solution of PDMS-1 into the cavity until the cavity is full of the mixed solution, and then standing to remove a small amount of bubbles.

f. Horizontally putting the mixture into a dryer at 100 ℃ for baking for 2 hours to carry out polymer curing and crosslinking.

g. After curing, in order to enable the lens to have excellent imaging effect and better stability, a small amount of PDMS-2 mixture is dipped by a clean glass rod, the PDMS-2 mixture is added to the central aperture of the iris diaphragm, a spin coater is arranged at a low speed of 500 rpm for 5 seconds, after the spin coating is finished, the PDMS-2 is horizontally placed into a 100 ℃ drying machine to be baked for 1 hour for curing, so that a thin gel film with higher hardness and a thickness of about 100 μm is covered on the blade of the iris diaphragm, and finally the PDMS gel lens is formed.

Humans can easily see objects at different distances because the ciliary muscles in the human eye change the curvature of the crystalline lens and thus the focal length of the human visual system. Inspired by human eye biomechanics and an automatic focusing function, the inventor designs an adaptive lens system based on PDMS gel of an iris diaphragm. The elastic crystalline lens of the human eye is contracted or expanded by ciliary muscles and zonules, similar to the mechanism of the human eye, and the PDMS gel lens is contracted or expanded by driving blades of an iris diaphragm which functions like muscles of the human eye. The cross-sectional structure of the lens is shown in fig. 2 and 3, and in the state of no pressure application, at the central opening area of the iris diaphragm, because PDMS-2 covers a thin gel film on the blade of the iris diaphragm, the surface profile is "flat" at the central aperture of the iris diaphragm, and the focal length is infinite. PDMS-2 acts as an encapsulation and reduces the effect of gravity on PDMS-1. In the expanded state, the aperture of the iris diaphragm in the central opening area is large, at this time the aperture is 3.55mm, and the PDMS gel lens has a longer focal length, as shown in FIG. 2. When the handle of the iris diaphragm is rotated counterclockwise and the aperture at the central opening is gradually decreased, the PDMS gel in the central area of the iris diaphragm will shrink due to the fixed volume and the elasticity of the PDMS gel, and accordingly the surface profile of the gel will become "flat" to "convex", which has a lens effect, and the focal length of the PDMS gel lens will also gradually decrease, as shown in fig. 3. In summary, the focal length of the lens will vary with the degree of protrusion of the gel surface profile due to the variation of the iris opening.

The experimental setup as shown in fig. 4 was used to measure the focal lengths of lenses having different apertures, and the PDMS gel lens prepared in this example was mounted on a linear metrology stage. The He — Ne laser beam (λ =0.633 μm) is collimated and expanded by the lens-1 and the lens-2. This beam acts as the incident light source for the PDMS gel lens. After passing through the PDMS gel lens, the beam was focused. The light intensity at the focus was received and analyzed using a CCD (SBIG ST-2000 XM) to obtain the curve of the focal length of the PDMS gel lens as a function of the aperture size. As shown in FIG. 5, when the iris diaphragm aperture is reduced from 3.55mm to 3.02mm, the focal length of the PDMS gel lens varies from infinity to 8.6mm, and the focal length varies greatly.

Comparative example

(1) PDMS material property under different mixture ratio of main agent and curing agent

The main agent and the curing agent of the PDMS polymer material (SYLGARD 184 of Dow Corning company) are respectively mixed according to the conventional ratio reported at present, namely the main agent and the curing agent are mixed according to the weight ratio of 10:1, 20:1 and 30:1, are uniformly stirred, are respectively and uniformly dripped on three same optical glass substrates with the thickness of 0.7mm, are placed on a spin coater, are spin-coated for 10s at the speed of 500r/min, are vacuumized for 10 min to remove bubbles, and are finally placed in a dryer with the temperature of 100 ℃ to be baked for 1 hour for curing.

The PDMS materials with the three proportions are all elastic films after being cured, and the elastic modulus E of the PDMS materials is 2.9683, 1.8245 and 1.1654 respectively. A large number of reports and experiments prove that the elastic modulus is gradually reduced, the elasticity is gradually increased and the hardness is gradually reduced along with the increase of the proportion of the main agent to the curing agent. The proportion of the PDMS as the main agent and the curing agent is 50: 1 and 80: 1, which forms a PDMS material in a gel state between liquid and solid. This is because as the ratio of the PDMS base to the curing agent increases, the two PDMS components cannot be completely polymerized, and the finally formed high molecular polymer PDMS material becomes softer and more flexible. If the ratio of the main agent to the curing agent is more than 100:1, the fluidity is enhanced and the stability is lowered.

(2) Liquid lens based on PDMS elastic membrane

The liquid lens using the elastic membrane has various types, such as pneumatic driving, electromagnetic driving and the like, but the principle of the liquid lens is to drive the PDMS elastic membrane to deform, so that the preparation process of the PDMS elastic membrane is included in the main lens preparation flow.

The PDMS elastic film for the liquid lens is generally prepared by spin coating. The spin coating method is to pour the PDMS liquid mixture which is fully mixed and has bubbles removed onto a glass or silicon substrate, and uniformly coat the PDMS mixture on the substrate by the centrifugal force generated when the spin coater runs at high speed. The method can accurately control the thickness of the obtained PDMS film by adjusting the rotation speed and the rotation time of the spin coater. However, in order to obtain a large focal length variation range and reduce driving force when manufacturing a liquid lens based on a PDMS elastic film, the required elastic film is generally of micron order, and when the PDMS film is thin, the adhesion of the PDMS film itself is strong, so that the PDMS film is tightly bonded to a substrate after curing, and the film is damaged by direct peeling. In addition, the method can not manufacture the PDMS film with the pattern, and the spin coating process has large waste and higher cost.

In addition, the liquid variable-focus micro lens has the advantage of wide zooming range, but is easy to leak liquid and influenced by gravity, generates electromagnetic interference when being driven by magnetism, and has slow response speed, large volume and overhigh driving voltage.

(3) Solid lens based on PDMS elastic membrane

a. For preparing a solid lens of PDMS elastic film, a molding method, a 3D printing method, or a spray printing method is currently reported.

The molding method for preparing the PDMS film is to copy the patterns on the positive mold with high cost or complex process by using PDMS as a material by utilizing the principle of a reverse mold so as to realize low-cost and mass production of products. The method has the main advantages that the PDMS film with the pattern can be manufactured, and the manufacturing equipment and the process conditions are not required in the manufacturing process. However, the method has a complex manufacturing flow, the thickness of the manufactured film is usually in the millimeter level, the precision is not high, and the cost is high.

The 3D printing method is to use PDMS as a material, design a three-dimensional structure model of the lens, and then spray-print the three-dimensional structure model by a spray printing machine or a 3D printing machine or print the three-dimensional structure model layer by layer in a gel medium to obtain a primary body of the three-dimensional structure model of the lens; and then curing after molding to finally obtain the lens.

The jet printing method comprises the steps of respectively injecting a PDMS elastomer and a curing agent into corresponding micro-injection pumps, setting the injection speed of the micro-injection pumps, adjusting the distance between an electronic jet printing micro-nozzle and a printing substrate, setting micro-injection parameters and three-dimensional workbench motion parameters in the electronic jet printing process, jetting PDMS micro-droplets onto the printing substrate by the electronic jet printing micro-nozzle according to the set micro-injection parameters, and forming the PDMS micro-droplet array through curing molding.

The three lens preparation methods have complex processes, and the obtained PDMS elastic film solid lens has a fixed focal length and cannot realize the zooming function.

b. For the variable-focus solid lens based on the PDMS elastic membrane, a variable-focus PDMS lens system based on an artificial iris is reported abroad, and a preparation method based on an electrostatic driving type PDMS micro lens is reported domestically.

The zoom lens system proposed by foreign Jong-Moon Choi comprises a PDMS elastic membrane lens, a wound SMA actuator and load arms. Its artificial iris (comprising the wound SMA actuator and load arms) is used to deform the shape of a resilient solid (PDMS) lens by stretching its aperture in the radial direction, thereby changing the focal length. Because the PDMS elastic film with the ratio of 10:1 is adopted as the lens, the hardness of the PDMS elastic film is larger, so that the shape change is generally accompanied with larger shape distortion, thereby causing larger image distortion, reducing the optical performance of the lens, and having small adjustable range of the focal length. In addition, its structure is complicated and miniaturization cannot be achieved.

The all-solid-state variable-focus electrostatic driven microlens based on the PDMS film, which is reported in China, is prepared by mixing a prepolymer and a curing agent in a weight ratio of 20: 1 is placed between two glass layers of different thickness containing the ring electrode actuator. When voltage is applied to the electrodes, coulomb force generated between the electrodes can force the glass film to bend, so that the whole lens structure is formed, and different voltages can cause the glass film to have different bending curvatures, so that the focal length of the micro lens is changed. The PDMS lens with the structure also has the problems of complex manufacturing process, small lens focal length change and image distortion.

Therefore, it can be seen from the above comparison that the physical properties of the PDMS materials with different ratios of the main agent and the curing agent are different. The embodiment of the invention adopts a method of proportioning a specific PDMS main agent and a curing agent to prepare the lens material-PDMS gel, which has the material properties between liquid and an elastic membrane, such as excellent transparency in a visible wavelength range, low surface roughness, high elasticity and better mechanical stability. The technical scheme of the invention solves the bottleneck problems of polarization correlation, mechanical instability, slow response speed, complex device structure and the like of the existing lens, 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 and the like of the lens. The characteristics are one of the leading development directions of the current adaptive lens device, can be used as an important technical basis for constructing a next generation of novel adaptive lens with higher performance and lower power consumption, and opens up a new visual angle for imaging and displaying, particularly development of switchable 2D/naked-eye 3D display and flexible display devices.

The hardness of the traditional lens prepared by adopting a PDMS elastic film is higher, and the PDMS elastic film has larger deformation when being used as a lens material, so that the imaging quality is poor. The technical scheme of the invention adopts the PDMS gel with high elasticity and better mechanical stability, and the focus-adjustable adaptive lens manufactured by the PDMS gel with the novel proportion greatly improves the imaging quality and other optical properties of the lens. In addition, compared with the PDMS elastic membrane lens, the lens prepared by the gel-state PDMS material has the advantages of simple production process, no need of complex demolding process, cost reduction, larger focal length variation range, better imaging quality and easier miniaturization and integration production.

The foregoing is a further detailed description of the invention in connection with specific preferred embodiments and it is not intended to limit the invention to the specific embodiments described. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims

1. A PDMS gel-based adaptive lens, comprising: the device comprises PDMS gel and a driving mechanism, wherein the driving mechanism drives the change of the curvature radius of the PDMS gel to realize zooming;

The PDMS gel is prepared by mixing a PDMS prepolymer and a curing agent according to the weight ratio of 50-80: 1, and heating and curing;

the device comprises an iris diaphragm and an optical substrate, wherein a 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 positioned in the cavity;

a first PDMS gel is arranged in the chamber, a layer of gel film covers the blade of the iris diaphragm, the gel film is prepared from a second PDMS gel, the weight ratio of a PDMS prepolymer for preparing the first PDMS gel to a curing agent is higher than that of the PDMS prepolymer for preparing the second PDMS gel to the curing agent, and the gel film covers the surface of the first PDMS gel;

the self-adaptive lens based on the PDMS gel is prepared by adopting the following steps:

step S1, mixing the PDMS prepolymer and the curing agent according to the weight ratio of the two proportions, pouring the mixture into a clean and dried container, uniformly stirring, and vacuumizing to remove bubbles to obtain a first PDMS gel and a second PDMS gel; the weight ratio of the PDMS prepolymer for preparing the first PDMS gel to the curing agent is 70-80: 1, and the weight ratio of the PDMS prepolymer for preparing the second PDMS gel to the curing agent is 50-60: 1;

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

step 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 of the PDMS gel, standing the PDMS gel to remove bubbles, and heating and curing the PDMS gel; the first PDMS gel is heated and cured at the temperature of 90-110 ℃ for 1-3 h;

step S4, applying a second PDMS gel to a surface of the iris diaphragm, and heating and curing the applied second PDMS gel to form a gel film; wherein the gel film is obtained by heating and curing after glue is homogenized on a glue homogenizing machine; the rotation speed of the spin coater is 200-700 rpm, the time is 3-8 s, the heating and curing temperature is 90-110 ℃, and the time is 0.5-2 h.

2. The PDMS gel-based adaptive lens of claim 1, wherein: the driving mechanism is a mechanical pressure, piezoelectric effect, thermal effect, electromagnetic pressure or fluid pressure driving mechanism.

3. The PDMS gel-based adaptive lens of claim 1, wherein: the thickness of the gel film is 10-200 μm.

4. The PDMS gel-based adaptive lens of claim 1, wherein:

the PDMS prepolymer is SYLGARD 184 from Dow Corning.