CN104391345B - Containing the Electrowetting type focus variable liquid lens of the Gradient Refractive Index Materials - Google Patents

Abstract

The invention discloses a kind of Electrowetting type focus variable liquid lens containing the Gradient Refractive Index Materials, belong to optical technical field.Its principal feature is, liquid lens front and rear surfaces adopts plano-convex lens and the plano-concave lens of the Gradient Refractive Index Materials of more easily processing respectively, compensate spherical aberration and aberration by gradient refractive index rate coefficient A, B, C of reasonably selecting and mate two lens, thus improve image quality of the present invention.In addition, employing can cut down the cavity that material makes liquid lens, not only can directly from extraction electrode cavity without the need to being coated with metal electrode at cavity inner wall, and ratio-frequency welding connection can be adopted to be welded with two lens by cavity, effectively improve sealing characteristics of the present invention.Instant invention overcomes general liquid lens and can only change focal length, can not the shortcoming of simultaneously achromatism and aberration, there is picture element excellent, optical system can be formed separately in application, compact, do not need other element to participate in the feature of imaging.

Description

Containing the Electrowetting type focus variable liquid lens of the Gradient Refractive Index Materials

Technical field

The invention belongs to optical technical field, relate to a kind of Electrowetting type focus variable liquid lens, particularly relate to a kind of Electrowetting type focus variable liquid lens containing the Gradient Refractive Index Materials.

Background technology

Electrowetting type focus variable liquid lens is a kind of novel optical element, and it is based on bionic concept, does not need to adopt any moving assembly, has certain autonomous zoom capabilities.Electrowetting type focus variable liquid lens is that the impressed voltage by changing liquid-solid interface controls liquid wetting property in solid face, thus realizes focal length change.It is wide that this lens have response time short, zooming range, non mechanical movable, the advantage that integrated performance is good.Thus by this element application in zoom system, pancreatic system, the function that traditional optical elements has been difficult to can be completed, avoid the shortcoming that traditional zoom system architecture is complicated, easy to wear.But this element is difficult to realize heavy caliber Zoom lens, and also make it apply because control voltage is too high to be limited to.

In recent years, external Duo Jia scientific research institution abolished people for many years and, to the understanding of solid lens, looked for another way, and was all devoted to the lens of development of new---and Electrowetting type focus variable liquid lens, achieve very ten-strike.The Electrowetting type focus variable liquid lens developed with Dutch PHILIPS Co. and French Varioptic company is for representative, and they can produce the liquid lens of several model now in batches.2007, French Varioptic company can produce the commercial liquid lens with providing unit point model.Wherein the working temperature of Arctic316 type liquid lens is-20 DEG C ~ 60 DEG C, can to 5cm to infinite remote object blur-free imaging, and the response time is less than 30ms.The structure of its liquid lens is detailed in patent USRE39874E1 and Ep1662276A1.But this Electrowetting type focus variable liquid lens can only change focal length, can not simultaneously achromatism and spherical aberration, be used alone and be unfavorable for high-quality imaging.

At present, the domestic research also having fractional unit to carry out Electrowetting type focus variable liquid lens manufacturing technology.The Electrowetting type hybrid refractive-diffractive zooming liquid lens that Xi'an ray machine is invented is detailed in patent publication No. CN101685170, the planar substrates of common Electrowetting type liquid lens is replaced with diffraction lens by it, add the design freedom of liquid lens, make monolithic liquid lens can realize apochromatism, spherical aberration when zoom.But there are following two shortcomings in this Electrowetting type hybrid refractive-diffractive zooming liquid lens: 1) because liquid lens is operated in visible light wave range, the diffraction lens mated with it also must operate at visible light wave range.Compared with infrared band, visible ray Diffractive Lenses Diffractive ring is closeer, and because liquid lens size is little, the visible ray diffraction lens tolerance of the use that matches is higher, technique is difficult to ensure machining precision; 2) adopt glue to seal between diffraction lens and liquid chamber, and glue contact with air and is easily oxidized, and can produce bubble in a liquid, zooming liquid lens overall performance is declined.

Summary of the invention

The technical problem to be solved in the present invention is, is difficult to processing for diffraction lens in hybrid refractive-diffractive zooming liquid lens, and the shortcoming of poor sealing performance, a kind of Electrowetting type focus variable liquid lens containing the Gradient Refractive Index Materials is provided.

For solving the problems of the technologies described above, Electrowetting type focus variable liquid lens provided by the invention comprises the first lens, cavity, conducting liquid, iknsulating liquid and the second lens, first lens are the positive focal length plano-convex lens that the Gradient Refractive Index Materials makes, its front surface is sphere, and rear surface is plane and is coated with ITO conducting film by chemical vapour deposition technique; Cavity is can cut down the top that material makes to have the inverted U-shaped right cylinder of through hole, and its internal surface of column and top surfaces externally and internally all apply hydrophobic dielectric film; Conducting liquid is the electrolyte solution that sodium chloride and water mix; Iknsulating liquid is mixed by silicone oil DC704 and dibromo-hexane; Second lens are the negative focal length plano-concave lens that the Gradient Refractive Index Materials makes, and its front surface is plane, and rear surface is sphere, and the external diameter of the second lens is identical with the external diameter of described cavity;

The bottom of described cavity is welded on by high-frequency heating welding process on the front surface of the second lens; Inject described iknsulating liquid and described conducting liquid in the inside of cavity successively according to the volume ratio of 1 ︰ 1, wherein iknsulating liquid contacts with described second lens; Positive wire is welded on the cylindrical outer surface of described cavity, and cathode conductor is welded on described conducting film, and conducting film is connected by high-frequency heating welding process with the top of cavity;

The Gradient Refractive Index Materials of described first lens and the second lens adopts optical glass or optical plastic or optical crystal, and the index distribution of the first lens and the second lens all should meet following formula:

$n^2\left(z\right)=A+\frac{{\mathrm{Bz}}^2}{z^2-C}$

In formula, A, B, C are the gradient refractive index rate coefficient of the first lens or the second lens, z is for true origin and along the coordinate figure of optical axis forward with the first lens front surface summit or the second lens front surface summit, n (z) is the refractive index on optical axis corresponding to z point coordinate value, as z=0, n (z)=A ^0.5;

Meanwhile, described electricity should meet with next group formula containing the spherical aberration of Electrowetting type focus variable liquid lens of the Gradient Refractive Index Materials and aberration:

$S_I=\underset{1}{\overset{2}{\mathrm{\Σ}}}{S}_{\mathrm{IG}}+\underset{1}{\overset{2}{\mathrm{\Σ}}}{h}_i{P}_i=0$

$S_{\mathrm{IC}}=\underset{1}{\overset{2}{\mathrm{\Σ}}}{S}_{\mathrm{ICG}}+\underset{1}{\overset{2}{\mathrm{\Σ}}}{h}_i^2{C}_i=0$

$p_i=\underset{i=1}{\overset{k}{\mathrm{\Σ}}}{\left(\frac{{\mathrm{\Δu}}_i}{\mathrm{\Δ}\frac{i}{n}}\right)}^2\mathrm{\Δ}\frac{u_i}{n_i}$

C _i＝Φ _i/υ _i

In formula: S _iit is total spherical aberration of Electrowetting type focus variable liquid lens; S _iGit is the spherical aberration of the first lens or the second lens; S _{i C}it is total chromatism of position of Electrowetting type focus variable liquid lens; S _{i CG}it is the chromatism of position of the first lens or the second lens; h _ifor the height of light on i-th, i represents the optical surface of adjacent media, wherein, i=1 is the front surface of the first lens, and i=2 is the rear surface of the first lens, and i=3 is the interphase of conducting liquid and iknsulating liquid, i=4 is the front surface of the second lens, and i=5 is the rear surface of the second lens; u _ifor light is when through i-th and the angle of optical axis; n _ifor light to arrive in face of i-th through the refractive index of medium; Φ _ifor the focal power of iknsulating liquid or conducting liquid; υ _ifor its Abbe number.

Overall technology effect of the present invention is presented as the following aspects.

(1) the present invention is formed seal glass i.e. the first lens and second lens of Electrowetting type focus variable liquid lens both sides with the Gradient Refractive Index Materials, design for liquid lens provides the degree of freedom of aberration correction, under different zooms requires, by reasonably selecting the first lens and second lens gradient refractive index rate coefficient A, B, C, just can carry out picture element optimal design according to necessary requirement to the present invention, to compensate spherical aberration, thus improve image quality of the present invention.

(2) in the present invention, first lens and the second lens have employed the version of positive focal length plano-convex lens and negative focal length plano-concave lens respectively, in addition the Proper Match of lens material gradient refractive index rate coefficient, thus can compensate the aberration that liquid lens brings effectively.

(3) the present invention is compared with existing Electrowetting type hybrid refractive-diffractive zooming liquid lens, and the lens of the Gradient Refractive Index Materials more easily realize in processing, the request for utilization and the actual machining precision of lens is content with very little.

(4) in the present invention, employing can be cut down material and make cavity, electric conductivity on the one hand owing to can cut down material can direct extraction electrode, save the step being coated with metal electrode at cavity inner wall, can cut down between material and glass material on the other hand adopts ratio-frequency welding connection to connect, compared with the prior art adopting glue to carry out sealing, the sealing property that the method makes the present invention reach is better.

Accompanying drawing explanation

Fig. 1 is the front sectional view of Electrowetting type focus variable liquid lens of the present invention.

Fig. 2 is the structural representation of the first lens being coated with ITO conducting film.

Fig. 3 is the cavity body structure schematic diagram being coated with hydrophobic dielectric film.

Fig. 4 is the structural representation of the second lens.

Fig. 5 is vertical axial aberration curve map corresponding to the preferred embodiment of the present invention.

Fig. 6 is MTF curve map corresponding to the preferred embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing and preferred embodiment, the present invention is described in further detail.

As shown in Figure 1, Electrowetting type focus variable liquid lens preferred embodiment of the present invention comprises the first lens 1, cavity 2, conducting liquid 3, iknsulating liquid 4 and the second lens 5.The positive focal length plano-convex lens (see Fig. 2) that first lens 1 make for the Gradient Refractive Index Materials, its front surface is sphere 1-1, and rear surface is plane 1-2, and it is coated with ITO conducting film 1-3 by chemical vapour deposition technique, and the present embodiment thickness is 125nm.Cavity 2 is the inverted U-shaped right cylinder (see Fig. 3) that can cut down material making, its end face has through hole, inside surface and end face all apply hydrophobic dielectric film 2-1, in the present embodiment, hydrophobic dielectric film 2-1 is followed successively by 16 μm of thick Parylene C retes, 35 μm of thick polyimide film and 0.1 μm of thick Teflon AF1600 rete by the surface of cavity 2.Conducting liquid 3 is electrolyte solutions that NaCL and water mix, and in the present embodiment, NaCL and quality ratio are 8 ︰ 2.Iknsulating liquid 4 is that silicone oil DC704 and dibromo-hexane mix, and in the present embodiment, the mass ratio of silicone oil DC704 and dibromo-hexane is 9 ︰ 1, and silicone oil DC704 and dibromo-hexane are the goods shelf products of DowComing company.The negative focal length plano-concave lens (see Fig. 4) that second lens 5 make for the Gradient Refractive Index Materials, its front surface is plane 5-1, and rear surface is sphere 5-2, and its external diameter is identical with the external diameter of cavity 2.

See Fig. 1, the circular bottom part of cavity 2 is welded on the front surface 5-1 of the second lens 5 by high-frequency heating welding process.Inject iknsulating liquid 4 and conducting liquid 3 successively in the inside of cavity 2, namely iknsulating liquid 4 contacts with the second lens 5, volume ratio 1 ︰ 1 of iknsulating liquid 4 and conducting liquid 3.Positive wire 6-1 is welded on the outside surface of cavity 2, and cathode conductor 6-2 is welded on the conducting film 1-3 of the first lens 1, and the conducting film of the first lens is welded by high-frequency heating welding process with the end face of cavity 2.

The Gradient Refractive Index Materials of the first lens 1 and the second lens 5 adopts optical glass or optical plastic or optical crystal, and the index distribution of each lens material should meet following formula:

$n^2\left(z\right)=A+\frac{{\mathrm{Bz}}^2}{z^2-C}$

In formula, A, B, C are the gradient refractive index rate coefficient of the first lens material or the second lens material, z is for true origin and along the coordinate figure of optical axis forward with the first lens front surface summit or the second lens front surface summit, n (z) is the refractive index on optical axis corresponding to z point coordinate value, as z=0, n (z)=A ^0.5.

Meanwhile, the spherical aberration of Electrowetting type focus variable liquid lens of the present invention and aberration should meet with next group formula:

$S_I=\underset{1}{\overset{2}{\mathrm{\Σ}}}{S}_{\mathrm{IG}}+\underset{1}{\overset{2}{\mathrm{\Σ}}}{h}_i{P}_i=0$

$S_{\mathrm{IC}}=\underset{1}{\overset{2}{\mathrm{\Σ}}}{S}_{\mathrm{ICG}}+\underset{1}{\overset{2}{\mathrm{\Σ}}}{h}_i^2{C}_i=0$

$p_i=\underset{i=1}{\overset{k}{\mathrm{\Σ}}}{\left(\frac{{\mathrm{\Δu}}_i}{\mathrm{\Δ}\frac{i}{n}}\right)}^2\mathrm{\Δ}\frac{u_i}{n_i}$

C _i＝Φ _i/υ _i

In formula: S _iit is total spherical aberration of Electrowetting type focus variable liquid lens of the present invention; S _iGit is the spherical aberration of the first lens or the second lens; S _{i C}it is total chromatism of position of Electrowetting type focus variable liquid lens of the present invention; S _{i CG}it is the chromatism of position of the first lens or the second lens; h _ifor the height of light on i-th, i represents the optical surface of adjacent media; u _ifor light is when through i-th and the angle of optical axis; n _ifor light to arrive in face of i-th through the refractive index of medium.Φ _ifor the focal power of iknsulating liquid 4 or conducting liquid 3, υ _ifor its Abbe number.I=1,2,3,4,5 in the present invention, namely i=1 is the front surface 1-1 of the first lens 1, i=2 is the rear surface of the first lens, and i=3 is the interphase of conducting liquid and iknsulating liquid, and i=4 is the front surface of the second lens, and i=5 is the rear surface of the second lens.

In the present invention, conducting liquid 3 is fixing with the formula of iknsulating liquid 4, and their focal lengths under certain voltage are also fixing, i.e. the C of conducting liquid 3 _iwith the C of iknsulating liquid 4 _ibe given value, thus to spherical aberration and aberration contribution be also fixing.Therefore when designing of the present invention, often by gradient refractive index rate coefficient A, B, C of adjustment first lens and the second lens, the object eliminating total spherical aberration and total color difference is reached.

Principle of work of the present invention is, positive wire 6-1 and cathode conductor 6-2 is connected on the both positive and negative polarity of power supply respectively, during opening power, the incident beam being parallel to optical axis is assembled through the first lens 1, different voltage is applied by giving positive wire 6-1 and cathode conductor 6-2, make conducting liquid 3 and iknsulating liquid 4 realize zoom function, final light disperses post-concentration in the focus of focus variable liquid lens through the second lens 5 again.

The structural parameters of the preferred embodiment of the present invention are: the radius-of-curvature of the first sphere 1-1 is-21.32mm, and bore is 3mm, and the center thickness of the first lens is 0.5mm, and its gradient refractive index rate coefficient A is 1.870942, B be 0.202675, C is 0.370541; The radius-of-curvature of the second sphere 5-2 is-10.28mm, and bore is 4mm, and the center thickness of the second lens is 1mm, and its gradient refractive index rate coefficient A is-1.712654, B be 0.215945, C is 0.347586.

Parameter in preferred embodiment is carried out optical design emulation, obtains the aberration curve (see Fig. 5) corresponding to this preferred embodiment and corresponding MTF curve (see Fig. 6).As shown in Figure 5, the spherical aberration δ L:-0.025< δ L<0.01 of this preferred embodiment, aberration Δ L:3.9 × 10 ^-5< Δ L'< 9.2 × 10 ^-4, the second order spectrum of 0.5 visual field is 2.2 × 10 ^-5.As shown in Figure 6, the MTF of this preferred embodiment is close to diffraction limit.Above simulating, verifying shows, the various aberrations of the present embodiment obtain good correction, and picture element is excellent.

Claims (2)

1. the Electrowetting type focus variable liquid lens containing the Gradient Refractive Index Materials, comprise cavity (2), conducting liquid (3), iknsulating liquid (4), the first lens (1) and the second lens (5), described cavity (2) is can cut down the top that material makes to have the inverted U-shaped right cylinder of through hole, and positive wire (6-1) is welded on the cylindrical outer surface of described cavity (2); Described conducting liquid (3) is the electrolyte solution that sodium chloride and water mix, and described iknsulating liquid (4) is mixed by silicone oil DC704 and dibromo-hexane; It is characterized in that: the internal surface of column of described cavity (2) and top surfaces externally and internally all apply hydrophobic dielectric film (2-1); The positive focal length plano-convex lens that described first lens (1) make for the Gradient Refractive Index Materials, its front surface is sphere (1-1), and rear surface is plane (1-2) and is coated with ITO conducting film (1-3) by chemical vapour deposition technique; The negative focal length plano-concave lens that described second lens (5) make for the Gradient Refractive Index Materials, its front surface is plane (5-1), rear surface is sphere (5-2), and the external diameter of the second lens (5) is identical with the external diameter of described cavity (2);

The bottom of described cavity (2) is welded on the front surface (5-1) of the second lens (5) by high-frequency heating welding process; Inject described iknsulating liquid (4) and described conducting liquid (3) in the inside of cavity (2) successively according to the volume ratio of 1 ︰ 1, wherein iknsulating liquid (4) contacts with described second lens (5); Cathode conductor (6-2) is welded on described conducting film (1-3), and conducting film (1-3) is connected by high-frequency heating welding process with the top of cavity (2);

The Gradient Refractive Index Materials of described first lens (1) and the second lens (5) adopts optical glass or optical plastic or optical crystal, and the index distribution of the first lens (1) and the second lens (5) all should meet following formula:

$n^2\left(z\right)=A+\frac{{\mathrm{Bz}}^2}{z^2-C}$

In formula, A, B, C are the gradient refractive index rate coefficient of the first lens or the second lens, z is for being true origin with the first lens front surface (1-1) summit or the second lens front surface (5-1) summit and along the coordinate figure of optical axis forward, n (z) is the refractive index on optical axis corresponding to z point coordinate value, as z=0, n (z)=A ^0.5;

Meanwhile, the spherical aberration of the described Electrowetting type focus variable liquid lens containing the Gradient Refractive Index Materials and aberration should meet with next group formula:

$S_I=\underset{1}{\overset{2}{\&Sigma;}}{S}_{IG}+\underset{1}{\overset{2}{\&Sigma;}}{h}_i{P}_i=0$

$S_{IC}=\underset{1}{\overset{2}{\&Sigma;}}{S}_{ICG}+\underset{1}{\overset{2}{\&Sigma;}}{h}_i^2{C}_i=0$

$p_i=\underset{i=1}{\overset{k}{\&Sigma;}}{\left(\frac{{\mathrm{\&Delta;u}}_i}{\mathrm{\&Delta;}\frac{i}{n}}\right)}^2\mathrm{\&Delta;}\frac{u_i}{n_i}$

C _i＝Φ _i/υ _i

In formula: S _iit is total spherical aberration of Electrowetting type focus variable liquid lens; S _iGit is the spherical aberration of the first lens or the second lens; S _{i C}it is total chromatism of position of Electrowetting type focus variable liquid lens; S _{i CG}it is the chromatism of position of the first lens or the second lens; h _ifor the height of light on i-th, i represents the optical surface of adjacent media, wherein, i=1 is the front surface of the first lens, and i=2 is the rear surface of the first lens, and i=3 is the interphase of conducting liquid and iknsulating liquid, i=4 is the front surface of the second lens, and i=5 is the rear surface of the second lens; u _ifor light is when through i-th and the angle of optical axis; n _ifor light to arrive in face of i-th through the refractive index of medium; Φ _ifor the focal power of iknsulating liquid or conducting liquid; υ _ifor its Abbe number.

2. the Electrowetting type focus variable liquid lens containing the Gradient Refractive Index Materials according to claim 1, it is characterized in that: the center thickness of described first lens (1) is 0.5mm, its gradient refractive index rate coefficient A=1.870942, B=0.202675, C=0.370541; The radius-of-curvature of the first sphere (1-1) is-21.32mm, and bore is 3mm; The center thickness of described second lens (5) is 1mm, its gradient refractive index rate coefficient A=-1.712654, B=0.215945, C=0.347586; The radius-of-curvature of the second sphere (5-2) is-10.28mm, and bore is 4mm; Described hydrophobic dielectric film (2-1) is made up of 16 μm of thick Parylene C retes, 35 μm of thick polyimide film and 0.1 μm of thick Teflon AF1600 rete successively, wherein, the surface contact of Parylene C rete and described cavity (2); In described conducting liquid (3), the mass ratio of sodium chloride and water is 8 ︰ 2; In described iknsulating liquid (4), the mass ratio of silicone oil DC704 and dibromo-hexane is 9 ︰ 1.