CN113238307A - Self-adaptive variable-focus liquid lens based on variable electrowetting liquid level distance - Google Patents
Self-adaptive variable-focus liquid lens based on variable electrowetting liquid level distance Download PDFInfo
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- CN113238307A CN113238307A CN202110474537.1A CN202110474537A CN113238307A CN 113238307 A CN113238307 A CN 113238307A CN 202110474537 A CN202110474537 A CN 202110474537A CN 113238307 A CN113238307 A CN 113238307A
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B3/00—Simple or compound lenses
- G02B3/12—Fluid-filled or evacuated lenses
- G02B3/14—Fluid-filled or evacuated lenses of variable focal length
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/004—Optical devices or arrangements for the control of light using movable or deformable optical elements based on a displacement or a deformation of a fluid
- G02B26/005—Optical devices or arrangements for the control of light using movable or deformable optical elements based on a displacement or a deformation of a fluid based on electrowetting
Abstract
The invention discloses a self-adaptive variable-focus liquid lens based on variable electrowetting liquid level distance. The driving cavity is a cylindrical cavity which surrounds the imaging cavity and is coaxial with the imaging cavity. The imaging cavity is communicated with the driving cavity through two symmetrical small holes at the upper part and the lower part. Two liquid-liquid surfaces formed by two transparent liquids with the same density and different refractive indexes are arranged in the imaging cavity, and the two liquid-liquid surfaces can be independently controlled to adjust the curvature. Two liquid-liquid surfaces formed by two transparent liquids with the same density and different refractive indexes are also arranged in the driving cavity, and the two liquid-liquid surfaces can be independently controlled to push the liquids so as to control the distance between the two liquid-liquid surfaces in the imaging cavity. The device can be used for zooming, correcting aberration, changing optical path and the like in an optical system.
Description
Technical Field
The present invention relates to a liquid lens, and more particularly, to an adaptive variable focus liquid lens with variable liquid level spacing based on electrowetting.
Background
Nowadays, optical imaging systems are widely used in many fields such as engineering practice and video entertainment. In optical systems such as imaging lenses, projection lenses, cameras, optical microscopes, etc., lenses are indispensable elements. The conventional optical system usually adopts a solid glass lens, and because a single glass lens cannot realize zooming, the optical system usually adopts a lens group to realize zooming so as to change the magnification or the reduction of an image. The lens group is formed by changing the relative positions of a plurality of lenses. And the long-time movement between the components inevitably aggravates the friction loss of the components, thereby influencing the imaging quality and the service life of the whole optical system. The discovery of liquid lenses provides a new approach to zooming, which is an optical lens that uses fluidic technology to control light, and the lens body is typically made of liquid or flexible material, and the curvature of the lens body can be changed with the change of the driving force. However, most of the existing liquid lenses are single liquid surface curvature changes, focusing can be realized only by the liquid lenses, independent zooming and aberration correction cannot be realized, and zooming can be realized only by combining a plurality of liquid lenses. Moreover, the existing liquid lens has single performance, only can adjust the focal length of an optical path, and has no way to realize other functions such as changing the optical path and the like. For example, CN 201811043388.8 a liquid lens based on an electrowetting piston can only focus with a single liquid surface curvature change, and cannot achieve independent zoom imaging and aberration correction, and even cannot change the optical path. The CN201380070498.2 liquid lens with magnification control has double liquid level focusing, but the control method is electromagnetic drive, the structure is complex, and the function is also single. The paper Kopp, D., "All-liquid dual-lens electrowetting system", Applied Optics, 56(13), 3758 (2017) proposes a dual-level electrowetting control liquid lens; the zoom function can be realized, but the zoom range is limited by unchangeable distance between the two liquid surfaces, and the function is also single.
Disclosure of Invention
The invention provides a self-adaptive variable-focus liquid lens based on variable electrowetting liquid level distance. The structure of the lens is shown in the attached figure 1, and the lens comprises: the imaging cavity-plastic spacer comprises an incidence window, an imaging cavity-grounding electrode I, an imaging cavity-plastic spacer, an imaging cavity-bias electrode I, a dielectric hydrophobic layer, a driving cavity-plastic spacer, a driving cavity-bias electrode I, a driving cavity-grounding electrode, a hydrophobic layer, a driving cavity-bias electrode II, an imaging cavity-bias electrode II, a driving cavity-cover plate, an imaging cavity-grounding electrode II and an exit window. The driving cavity is a cylindrical cavity which surrounds the imaging cavity and is coaxial with the imaging cavity. The imaging cavity is communicated with the driving cavity through two symmetrical small holes at the upper part and the lower part.
The imaging cavity is filled with two transparent liquids with the same density but different refractive indexes, one of which is conductive and the other is insulating. The two liquids form two liquid-liquid surfaces in the imaging cavity and are respectively positioned in the middle of the two deflection electrodes. The driving cavity is filled with two conductive and insulating transparent liquids with the same density, and the two formed liquid-liquid levels are respectively positioned in the middle parts of the two deflection electrodes. The liquid filling mode in the two cavities is shown in figure 2. The liquid-liquid surface curvature in the imaging cavity can change along with the change of the voltage applied by the electrodes, thereby realizing the zooming effect. The liquid-liquid level in the driving cavity can also change along with the voltage change between the electrodes, and the change of the liquid level can push the liquid to flow into the imaging cavity through the communicating hole, so that the distance between the two liquid-liquid levels in the imaging cavity is changed, and the zooming effect is realized, as shown in attached figures 3 and 4.
The working principle of the self-adaptive variable-focus liquid lens with variable liquid level spacing is based on the electrowetting effect, and the inclination angle of the self-adaptive variable-focus liquid lens
The change in (c) is in accordance with the Young-Lippmann equation:
when the voltage between the bias electrode and the conductive liquid is increased continuously, the contact angle between the liquid interface and the side wall is reduced until the contact angle is saturated, which is expressed as the change of the liquid level curvature and the surge of the conductive liquid towards the insulating liquid.
Preferably, the driving cavity is a cylindrical cavity which surrounds the imaging cavity, is coaxial with the imaging cavity and is communicated with the imaging cavity;
preferably, the distance between the two liquid levels in the imaging chamber is adjustable by the control of the driving chamber.
In summary, the invention has the following advantages:
two independently adjustable liquid-liquid surfaces are arranged in the cylindrical imaging cavity, focal length change can be realized under the electrowetting effect due to the refractive index difference of the two liquids, and zoom imaging and aberration correction can also be realized by matching of the two liquid surfaces; in addition, two liquid-liquid surfaces which can be independently regulated and controlled are also arranged in a cylindrical driving cavity which surrounds the imaging cavity and is coaxial and communicated with the imaging cavity, and the distance between the two liquid surfaces in the imaging cavity can be controlled by controlling the liquid surface change in the driving cavity due to the conduction of the two cavities.
The double liquid levels in the imaging cavity are controlled to be flat, the distance between the double liquid levels in the imaging cavity is controlled by the driving cavity, and the device has the function of changing the optical path due to the difference of the refractive indexes of the two liquids.
Drawings
FIG. 1 is a cross-sectional view of an adaptive variable focus liquid lens structure based on variable electrowetting liquid level spacing.
FIG. 2 is a schematic sectional view of an initial liquid-liquid level state structure in an adaptive variable-focus liquid lens based on variable electrowetting liquid level distance.
Fig. 3 is a schematic diagram of the principle of forming a positive lens based on an adaptive variable focus liquid lens with variable electrowetting liquid level spacing.
Fig. 4 is a schematic diagram of the principle of forming a negative lens based on an adaptive variable focus liquid lens with variable electrowetting liquid level spacing.
FIG. 5 is a schematic diagram showing the relationship between the focal length and the voltage and the distance variation when forming a positive lens based on an adaptive variable liquid lens with variable electrowetting liquid level distance.
FIG. 6 is a schematic diagram showing the relationship between the focal length and the voltage and the distance variation when a negative lens is formed by an adaptive variable focus liquid lens based on variable electrowetting liquid level distance.
FIG. 7 is a zemax simulation graph and aberration curve chart of an adaptive variable focus liquid lens with variable electro-wetting liquid level spacing at a short focal length of 25 mm.
FIG. 8 is a zemax simulation and aberration plot for an electrowetting-based variable liquid level spacing adaptive variable focus liquid lens at a telephoto focal length of 30 mm.
FIG. 9 is a zemax simulation and a dot-column plot for a system based on an adaptive variable focus liquid lens with variable electrowetting liquid level spacing at a liquid-liquid level spacing of 1 mm.
FIG. 10 is a zemax simulation and a dot-column plot for a system based on an adaptive variable focus liquid lens with variable electrowetting liquid level spacing at a liquid-liquid level spacing of 6 mm.
The reference numbers in the figures are:
1 incidence window, 2 imaging cavity-grounding electrode I, 3 imaging cavity-plastic gasket, 4 imaging cavity-bias electrode I, 5 dielectric hydrophobic layer, 6 driving cavity-plastic gasket, 7 driving cavity-bias electrode I, 8 driving cavity-grounding electrode, 9 hydrophobic layer, 10 driving cavity-bias electrode II, 11 imaging cavity-bias electrode II, 12 driving cavity-cover plate, 13 imaging cavity-grounding electrode II, 14 exit window, 15 imaging cavity-conductive liquid, 16 imaging cavity-insulating liquid, 17 driving cavity-insulating liquid, 18 driving cavity-conductive liquid, 19 communication hole, 20 glass lens, it should be understood that the above-described figures are merely schematic and are not drawn to scale.
Detailed Description
The present invention will be further described in detail below based on an embodiment of an electrowetting variable liquid level spacing adaptive variable focus liquid lens according to the present invention. It should be noted that the following examples are only for illustrative purposes and should not be construed as limiting the scope of the present invention, and that the skilled person in the art may make modifications and adaptations of the present invention without departing from the scope of the present invention.
One embodiment of the invention is: first, the device structure is as follows: the imaging cavity is composed of an aluminum alloy circular ring, an aluminum alloy circular tube, a plastic gasket, an incident window and an exit window, wherein the inner diameter of the imaging cavity is 5mm, and the outer diameter of the imaging cavity is 6 mm. The structure is shown in figure 1, the imaging cavity is an incidence window made of glass materials from top to bottom, and the thickness of the imaging cavity is 0.5 mm; the thickness of the grounding electrode I of the aluminum alloy circular ring is 0.5 mm; an insulating plastic gasket with the thickness of 0.5 mm; the length of a bias electrode I of the aluminum alloy circular tube is 5mm, a dielectric hydrophobic layer formed by combining UV glue and Teflon is covered in the bias electrode I, and the total thickness of the bias electrode I is about 3 mu m; a plastic gasket with the lower end of 0.5mm thick; a bias electrode II of an aluminum alloy circular tube is arranged below the substrate, the length of the bias electrode II is 17mm, and a dielectric hydrophobic layer formed by combining UV glue and Teflon with the thickness of about 3 mu m is covered inside the bias electrode II; the difference with the bias electrode I is that the upper port of the circular tube of the bias electrode II is provided with two symmetrical gaps with the length of 1mm and the width of 3mm, the position 1mm away from the edge of the lower end is also provided with two symmetrical gaps with the length of 1mm and the width of 3mm, the four gaps are jointly used as communication holes for communicating the driving cavity, and meanwhile, the outer wall of the circular tube of the aluminum alloy used as the bias electrode II is covered with a Teflon hydrophobic layer with the thickness of about 3 mu m; and a plastic gasket with the thickness of 0.5mm is arranged below the offset electrode II, and an aluminum alloy annular grounding electrode II with the thickness of 0.5mm and a glass material exit window with the thickness of 0.5mm are arranged at the lower end of the plastic gasket. The driving cavity is composed of an aluminum alloy circular ring with the thickness of 0.5mm, two plastic gaskets with the thickness of 0.5mm and two aluminum alloy circular tubes with the length of 6.5 mm. They all had an inner diameter of 11mm and an outer diameter of 12 mm. The upper and lower plastic cover plates with the thickness of 0.5mm, the outer diameter of 12mm and the inner diameter of 6mm respectively seal the driving cavity. The aluminum alloy circular ring is used as a common grounding electrode in the middle, two aluminum alloy circular pipes are used as bias electrodes at two ends, and UV glue and Teflon dielectric hydrophobic layers with the thickness of about 3 mu m are covered on the two bias electrodes. A plastic gasket is provided between the ground electrode and the bias electrode to prevent short circuiting. The uppermost end of the driving cavity is flush with the communicating hole at the upper end of the imaging cavity, and the lowermost end of the driving cavity is flush with the communicating hole at the lower end of the imaging cavity. Conductive liquid filled in the imaging cavity and the driving cavity is NaCl aqueous solution, insulating liquid is colorless transparent silicone oil, the refractive index of the NaCl aqueous solution is 1.33, and the Abbe number is 55.8. The colorless transparent silicone oil had a refractive index of 1.65 and an Abbe number of 62.8.
The working band adopted by the embodiment is 380nm-760 nm. Applying a voltage to the present invention can effect a change in focal length. In the initial state, the curvatures of the liquid-liquid surfaces in the imaging cavity and the driving cavity under the action of the surface tension of the liquid are shown in the attached figure 2. When the bias electrode I in the imaging cavity applies voltage 43V to 62V, the bias electrode II in the imaging cavity applies voltage 23V to 43V, and the bias electrode II in the driving cavity applies voltage 23V to 62V, the system is a positive lens, as shown in FIG. 3. When the bias electrode I in the imaging cavity applies 23V to 43V, the bias electrode II applies 43V to 62V, and the bias electrode I in the driving cavity applies 23V to 62V, the system is a negative lens, as shown in FIG. 4. It should be noted that in the embodiment of the present invention, the driving voltage of the liquid lens is 23V, so that the device cannot be driven when the voltage is 0-23V. FIG. 5 shows the relationship between applied voltage, liquid-liquid level spacing and focal length for system variation in the forward focus range, with the focal length adjustment range of the lens being (9 mm, ∞). FIG. 6 shows the relationship between applied voltage, liquid-liquid level spacing and focal length for system variation in the negative focal range, with the focal length adjustment range of the lens being (-infinity, -10 mm).
The working band adopted by the embodiment is 380nm-760 nm. The application of voltage to the invention can realize zoom imaging and correct aberration. By zemax simulation, the curvature of the upper liquid level is 46.90mm and the curvature of the lower liquid level is 6.76mm by controlling the upper and lower independent electrodes in the imaging cavity in a short-focus state. And the liquid level upwelling is injected into the imaging cavity through the communicating hole by applying voltage to the driving cavity deflection electrode I, so that the liquid-liquid level distance in the imaging cavity is 6.32mm, at the moment, the focal length of the system is 25mm and the aberration can be well inhibited, and the attached figure 7 is a zemax simulation graph and an aberration curve graph when the short focal length of the system is 25 mm; in a long focus state, the curvature of the upper liquid level is 52.59mm and the curvature of the lower liquid level is 7.69mm by controlling the upper and lower independent electrodes in the imaging cavity. And the liquid level downward surge is injected into the imaging cavity through the communicating hole by applying voltage through the driving cavity deflection electrode II, so that the liquid-liquid level distance in the imaging cavity is 0.2mm, at the moment, the focal length of the system is 30mm and the aberration can be well inhibited, and the attached figure 8 is a zemax simulation graph and an aberration curve graph when the telephoto focal length of the system is 30 mm;
the working band adopted by the embodiment is 380nm-760 nm. The application of voltage to the invention can realize the function of changing the optical path. By zemax simulation, the device of the invention can be used for controlling the radius of a focus diffuse spot of a common glass lens by changing the optical path, and the curvature of upper and lower double liquid surfaces is infinite, namely the liquid level, by controlling upper and lower independent electrodes in an imaging cavity in an initial state. And the liquid level downward surge is injected into the imaging cavity through the communicating hole by applying voltage through the driving cavity deflection electrode II, so that the liquid-liquid level distance in the imaging cavity is 1mm, at the moment, the diffuse spot RMS radius is 3.466um under the state through system simulation, and the attached figure 9 is a zemax simulation graph and a dot-column graph of the system when the liquid-liquid level is 1 mm. And thirdly, removing the voltage applied by the driving cavity deflection electrode II, applying the voltage applied by the driving cavity deflection electrode I, and injecting the liquid level upwelling into the imaging cavity through the communicating hole, so that the liquid-liquid level distance in the imaging cavity is 6mm, at the moment, the diffuse spot RMS radius is 45.630um under the state through system simulation, and the attached figure 10 is a zemax simulation graph and a dot-column graph of the system when the liquid-liquid level is 6 mm.
Claims (4)
1. An adaptive variable focus liquid lens with variable electrowetting-based liquid level spacing, comprising: the imaging cavity and the driving cavity are formed, and the driving cavity is a cylindrical cavity which surrounds the outside of the imaging cavity and is coaxial with the imaging cavity; the imaging cavity is communicated with the driving cavity through two symmetrical small holes at the upper part and the lower part, and is characterized in that two liquid-liquid surfaces formed by two transparent liquids with the same density and different refractive indexes are arranged in the imaging cavity, and the two liquid-liquid surfaces can be independently controlled to adjust the curvature; two liquid-liquid surfaces formed by two transparent liquids with the same density and different refractive indexes are also arranged in the driving cavity, and the two liquid-liquid surfaces can be independently controlled to push the liquids so as to control the distance between the two liquid-liquid surfaces in the imaging cavity.
2. The electrowetting-based variable liquid level spacing-based adaptive variable focus liquid lens according to claim 1, wherein the driving cavity is a cylindrical cavity which surrounds the imaging cavity, is coaxial with the imaging cavity and is communicated with the imaging cavity.
3. The electrowetting-based variable liquid level spacing adaptive zoom liquid lens according to claim 1, wherein a spacing between two liquid levels in the imaging chamber is adjustable by a driving chamber control.
4. The electrowetting-based variable liquid level spacing adaptive zoom lens of claim 1, wherein the driving of the liquid level variation in the imaging chamber and the driving chamber is based on an electrowetting principle.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114740555A (en) * | 2022-05-13 | 2022-07-12 | 四川大学 | Multifunctional liquid lens with adjustable surface shape and diaphragm |
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| CN101194188A (en) * | 2005-06-10 | 2008-06-04 | 皇家飞利浦电子股份有限公司 | Variable fluid lens having two menisci |
| CN104937446A (en) * | 2012-11-16 | 2015-09-23 | 伦斯勒理工学院 | Liquid lens with magnification control |
| CN109031483A (en) * | 2018-09-07 | 2018-12-18 | 四川大学 | A kind of liquid lens based on the wet piston of electricity |
| CN109765740A (en) * | 2019-03-18 | 2019-05-17 | 北京航空航天大学 | A kind of optofluidic lens based on drop separation |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101194188A (en) * | 2005-06-10 | 2008-06-04 | 皇家飞利浦电子股份有限公司 | Variable fluid lens having two menisci |
| CN101046554A (en) * | 2006-03-28 | 2007-10-03 | 索尼株式会社 | Optical element and imaging apparatus |
| CN104937446A (en) * | 2012-11-16 | 2015-09-23 | 伦斯勒理工学院 | Liquid lens with magnification control |
| CN109031483A (en) * | 2018-09-07 | 2018-12-18 | 四川大学 | A kind of liquid lens based on the wet piston of electricity |
| CN109765740A (en) * | 2019-03-18 | 2019-05-17 | 北京航空航天大学 | A kind of optofluidic lens based on drop separation |
Cited By (1)
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| CN114740555A (en) * | 2022-05-13 | 2022-07-12 | 四川大学 | Multifunctional liquid lens with adjustable surface shape and diaphragm |
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