Lens with variable focus

Abstract

A variable focus lens comprising a chamber ( 12 ) filled with a first liquid ( 13 ), a drop of a second liquid ( 11 ) being disposed at rest on a region of a first surface of an insulating wall of the chamber, the first and second liquids being non miscible, of different optical indexes and of substantially same density. The first liquid is conductive and the second liquid is insulating. The lens further comprises means for applying a voltage between the conductor liquid and an electrode ( 16 ) placed on the second surface of said wall; and centering means for maintaining the centering of the edge of the drop while the voltage is applied and for controlling the shape thereof.

1. A variable focus lens comprising a chamber ( 12 ) filled with a first liquid ( 13 ), a drop of a second liquid ( 11 ) being disposed at rest on a region of a first surface of an insulating wall of the chamber, the first and second liquids being non miscible, of different optical indexes and of substantially same density, characterized in that:
 the first liquid is conductive;  
 the second liquid is insulating;  
 in that it comprises: 
 means for applying a voltage between the conductor liquid and an electrode ( 16 ;  26 ;  35 - 37 ;  75 - 79 ) placed on the second surface of said wall; and  
 centering means for maintaining the centering of the edge of the drop while the voltage is applied and for controlling the shape thereof.  
 
 
     
     
       2. The variable focus lens according to  claim 1 , in which the centering means allows a continuous maintaining of the centering of the drop and a continuous control of the shape of the edge of the drop while a varying voltage is applied by said means for applying a voltage. 
     
     
       3. The variable focus lens according to  claim 2 , in which the first surface is substantially flat, the contact region ( 15 ) is circular and centered about an axis (O) which is perpendicular to the first surface. 
     
     
       4. The variable focus lens according to  claim 3 , in which the centering means corresponds to a progressive thickening of the second surface of the wall of the chamber towards said axis, said electrode ( 26 ) being applied against said second surface. 
     
     
       5. The variable focus lens according to  claim 3 , in which the centering means corresponds to a radial decrease of the wetting with respect to the first liquid ( 13 ), towards the center of said contact region ( 15 ) with the second liquid. 
     
     
       6. The variable focus lens according to  claim 3 , in which the centering means corresponds to a radial gradient of the dielectric constant of said wall of the chamber ( 53 ) at the level of said contact region ( 15 ) with the second liquid. 
     
     
       7. The variable focus lens according to  claim 1 , in which the first surface is substantially flat, the contact region ( 15 ) is circular and centered about an axis (O) perpendicular to the first surface, and wherein the centering means comprises an electrode formed of one or several circular concentric strips ( 35 - 37 ) insulated from each other, centered about said axis, the circular strips being supplied by distinct voltage sources of values decreasing towards said axis. 
     
     
       8. The variable focus lens according to  claim 1 , in which the chamber is cylindrical, the first surface is the internal surface of the chamber, the contact region with the second liquid corresponds to a cylindrical section of the chamber, the centering means is comprised of one or several cylindrical electrodes of same diameter, insulated from each other, placed side by side against the external surface of the chamber at the level of the border of said contact region, the electrodes being supplied by different voltage of values decreasing towards the center of said contact region. 
     
     
       9. The variable focus lens according to  claim 1 , in which the first surface is substantially flat, the contact region ( 15 ) is rectangular and symmetric with respect to an axis (O) perpendicular to the first surface and the centering means is comprised of an electrode formed of one or several rectangular concentric strips insulated from each other, symmetric with respect to said axis (O), the rectangular strips being supplied by distinct voltage sources of decreasing values towards said axis. 
     
     
       10. The variable focus lens according to  claim 1 , in which said wall is comprised of two non parallel planes and in which said region bridges said two planes. 
     
     
       11. A variable focus lens comprising:
   a chamber containing a first liquid, the first liquid being conductive;        a drop of a second liquid being disposed on a contact region of a first surface of an insulating wall of the chamber, the second liquid being insulating, the first and second liquids being non miscible, of different optical indexes and of substantially same density;        a voltage source configured for applying a voltage between the first liquid and an electrode placed on a second surface of said wall; and        centering means for maintaining the centering of the edge of the drop while the voltage is applied and for controlling the shape thereof.     
     
     
       12. The variable focus lens according to  claim 11 , in which the centering means allows a continuous maintaining of the centering of the drop and a continuous control of the shape of the edge of the drop while a varying voltage is applied by said voltage source. 
     
     
       13. The variable focus lens according to  claim 12 , in which the first surface is substantially flat, the contact region is circular and centered about an axis which is perpendicular to the first surface. 
     
     
       14. The variable focus lens according to  claim 13 , in which the centering means corresponds to a progressive thickening of the second surface of the wall of the chamber towards said axis, said electrode being applied against said second surface. 
     
     
       15. The variable focus lens according to  claim 13 , in which the centering means corresponds to a radial decrease of the wetting with respect to the first liquid, towards the center of said contact region with the second liquid. 
     
     
       16. The variable focus lens according to  claim 13 , in which the centering means corresponds to a radial gradient of the dielectric constant of said wall of the chamber at the level of said contact region with the second liquid. 
     
     
       17. The variable focus lens according to  claim 11 , in which the first surface is substantially flat, the contact region is circular and centered about an axis perpendicular to the first surface, and wherein the centering means comprises an electrode formed of one or several circular concentric strips insulated from each other, centered about said axis, the circular strips being supplied by distinct voltage sources of values decreasing towards said axis. 
     
     
       18. The variable focus lens according to  claim 11 , in which the chamber is cylindrical, the first surface is the internal surface of the chamber, the contact region with the second liquid corresponds to a cylindrical section of the chamber, and the centering means comprises:
   one or more cylindrical electrodes of same diameter, insulated from each other, placed side by side against an external surface of the chamber at the level of the border of said contact region, the electrodes being supplied by different voltages of values decreasing towards the center of said contact region.     
     
     
       19. The variable focus lens according to  claim 11 , in which the first surface is substantially flat, the contact region is rectangular and symmetric with respect to an axis perpendicular to the first surface, and the centering means comprises:
   an electrode formed of one or more rectangular concentric strips insulated from each other, symmetric with respect to said axis, the rectangular strips being supplied by distinct voltage sources of decreasing values towards said axis.     
     
     
       20. The variable focus lens according to  claim 11 , in which said wall is comprised of two non parallel planes and in which said contact region bridges said two planes. 
     
     
       21. The variable focus lens according to  claim 14 , wherein the progressive thickening of the second surface comprises a dielectric drop centered about said axis. 
     
     
       22. The variable focus lens according to  claim 11 , in which the first surface is substantially flat, the contact region is circular and centered about an axis perpendicular to the first surface, and wherein the centering means comprises an electrode formed of circular concentric strips insulated from each other, centered about said axis, the concentric strips being connected to each other via switches configured to vary the number of concentric strips to which a voltage is applied to vary the shape of the drop. 
     
     
       23. The variable focus lens according to  claim 11 , wherein the first surface has one of a concave and a convex shape. 
     
     
       24. The variable focus lens according to  claim 11 , wherein the contact region has a high wetting with respect to the drop. 
     
     
       25. The variable focus lens according to  claim 11 , wherein the contact region has a low wetting with respect to the first liquid, and a region of the first surface surrounding the contact region has a high wetting with respect to the first liquid. 
     
     
       26. A variable focus lens comprising:
   a chamber containing a first liquid, the first liquid being conductive;        a drop of a second liquid being disposed on a contact region of a first surface of an insulating wall of the chamber, the second liquid being insulating, the first and second liquids being non miscible, of different optical indexes and of substantially same density;        a voltage source configured for applying a voltage between the first liquid and a second conducting liquid contacting a second surface of said wall; and        centering means for maintaining the centering of the edge of the drop while the voltage is applied and for controlling the shape thereof.     
     
     
       27. An array of variable focus lenses, each of the lenses in the array comprising:
   a chamber containing a first liquid, the first liquid being conductive;        a drop of a second liquid being disposed on a contact region of a first surface of an insulating wall of the chamber, the second liquid being insulating, the first and second liquids being non miscible, of different optical indexes and of substantially same density;        a voltage source configured for applying a voltage between the first liquid and an electrode placed on a second surface of said wall; and        centering means for maintaining the centering of the edge of the drop while the voltage is applied and for controlling the shape thereof.     
     
     
       28. The array of variable focus lenses according to  claim 27 , wherein the lenses are arranged in groups of three. 
     
     
       29. The array of variable focus lenses according to  claim 28 , wherein the groups of three comprises lenses colored in red, blue and green. 
     
     
       30. The array of variable focus lenses according to  claim 27 , wherein the lenses are arranged to form part of a color screen. 
     
     
       31. The variable focus lens according to  claim 11 , wherein the first liquid comprises water loaded with salts. 
     
     
       32. The variable focus lens according to  claim 11 , wherein the second liquid comprises at least one of an oil, an alkane, and a blend of alkanes. 
     
     
       33. The variable focus lens according to  claim 11 , wherein the insulating wall comprises a glass plate treated with silane. 
     
     
       34. The variable focus lens according to  claim 11 , wherein the insulating wall comprises a glass plate coated with a coating comprising fluorinated polymer. 
     
     
       35. The variable focus lens according to  claim 34 , wherein the insulating wall comprises a glass plate coated with a coating comprising a sandwich of fluorinated polymer, epoxy resin and polyethylene. 
     
     
       36. The variable focus lens according to  claim 11 , wherein the drop has a rest diameter of about  6  mm. 
     
     
       37. A variable focus lens comprising:
   a liquid containment structure having a wall made of insulating material;        a first, conductive liquid contained in the liquid containment structure and being in contact with the wall;        a drop of a second, insulating liquid being disposed on a contact region of a first insulating surface of the wall of the liquid containment structure, the first and second liquids being non miscible and of different optical indexes;        an electrode insulated from the first liquid and positioned in the vicinity where the first liquid is in contact with the wall; and        a voltage source configured for creating an electric field between the first liquid and the electrode.     
     
     
       38. A variable focus lens according to  claim 37 , wherein the wall of the liquid containment structure comprises a flat wall member. 
     
     
       39. A variable focus lens according to  claim 37 , wherein the wall of the liquid containment structure comprises a cylindrical wall section. 
     
     
       40. A variable focus lens according to  claim 39 , wherein the electrode comprises at least one cylindrical electrode surrounding the cylindrical wall section. 
     
     
       41. A variable focus lens according to  claim 37 , wherein the first and second liquids have substantially the same density. 
     
     
       42. A variable focus lens according to  claim 37 , further comprising a centering means for maintaining the centering of the drop about its optical axis and for controlling the shape of the drop while the voltage is applied. 
     
     
       43. A variable focus lens according to  claim 42 , wherein the centering means comprises a cylindrical wall section containing the drop. 
     
     
       44. A variable focus lens comprising:
   a chamber having a wall of insulating material;        a first liquid being disposed within the chamber and contacting the wall of the chamber, the first liquid being conducting;        a second liquid being disposed within the chamber and having an interface with the first liquid, the second liquid being insulating, the first and second liquids being non miscible;        an electrode positioned on the opposite side of the wall with respect to the first liquid; and        a voltage source configured for applying a voltage between the first liquid and the electrode so as to change the wetability between the first liquid and the wall and thereby change the shape of the interface between the first liquid and the second liquid.     
     
     
       45. A variable focus lens according to  claim 44 , wherein the chamber wall comprises a cylindrical wall section. 
     
     
       46. A variable focus lens according to  claim 44 , wherein the first and second liquids have substantially the same density. 
     
     
       47. A method of forming a lens of a variable focus lens, comprising:
   providing a chamber containing a first liquid and a second liquid, the first liquid being conductive and contacting a wall of the chamber, the second liquid having an interface with the first liquid, the second liquid being insulating, the first and second liquids being non miscible, the wall being insulating; and        providing a voltage source for applying a voltage between the first liquid and an electrode so as to increase the wetting between the first liquid and the wall and thereby change the shape of the interface between the first liquid and the second liquid.     
     
     
       48. A method of forming a lens of a variable focus lens, comprising:
   providing a chamber containing a first liquid and a second liquid, the first liquid being conductive and contacting a wall of the chamber, the second liquid having an interface with the first liquid, the second liquid being insulating, the first and second liquids being non miscible; and        providing a plurality of distinctive voltage sources for applying a plurality of distinctive voltages between the first liquid and an electrode to thereby change the shape of the interface between the first liquid and the second liquid.     
     
     
       49. The method of forming a lens of a variable focus lens according to  claim 48 , wherein at least one of the plurality of the voltage sources comprises an alternating voltage source. 
     
     
       50. The method of forming a lens of a variable focus lens according to  claim 48 , wherein at least one of the plurality of the voltage sources comprises an alternating voltage source having a frequency range between  50  and  10 , 000  Hz. 
     
     
       51. The method of forming a lens of a variable focus lens according to  claim 48 , wherein the first and second liquids have substantially the same density. 
     
     
       52. A method of forming a lens of a variable focus lens, comprising:
   providing a chamber containing a first liquid and a drop of a second liquid, the first liquid being conductive, the second liquid having an interface with the first liquid, the second liquid being insulating, the first and second liquids being non miscible, and of different optical indexes; and        providing a voltage source for varying a voltage so as to maintain the centering of the drop and to continuously control the shape of the edge of the drop.     
     
     
       53. A method of forming a lens of a variable focus lens, comprising:
   providing a chamber containing a first liquid and a drop of a second liquid, the first liquid being conductive, the second liquid having an interface with the first liquid, the second liquid being insulating, the first and second liquids being non miscible, and of different optical indexes; and        providing a voltage source capable of applying a voltage so that the electric field decreases radially toward a center of a contact region upon which the drop is disposed.     
     
     
       54. A method of forming a lens of a variable focus lens, comprising:
   providing a chamber containing a first liquid and a drop of a second liquid, the first liquid being conductive, the second liquid having an interface with the first liquid, the second liquid being insulating, the first and second liquids being non miscible, and of different optical indexes; and        providing a voltage source capable of controlling the shape of the edge of the drop by varying the number of electrodes to which a voltage is applied.     
     
     
       55. A method of changing the focus of a variable focus lens of the type comprising a liquid containment structure having a wall of insulating material, a body of a first, conductive liquid in contact with the wall, a drop of a second, insulating liquid in contact with the first liquid to form an interface therebetween, wherein the first and second liquids are non miscible and have different optical indexes, and a voltage source, the method comprising:
   selectively applying a voltage differential between the first liquid and the wall sufficient to change the wetability of the first liquid with respect to the wall to change the shape of the body of the first liquid; and        using the change in the shape of the body of first liquid to change the shape of the interface between the first and second liquids.     
     
     
       56. A method of changing the focus of a variable focus lens according to  claim 55 , wherein the liquid containment structure comprises a cylindrical wall section. 
     
     
       57. A method of changing the focus of a variable focus lens according to  claim 55 , wherein the first and second liquids have substantially the same density. 
     
     
       58. A method of changing the focus of a variable focus lens, comprising:
   selectively applying a voltage across a body of a first, conductive liquid sufficient to change the shape of the body of the first liquid; and        using the change in the shape of the body of first liquid to change the shape of an interface between the first liquid and a drop of a second, insulating liquid in contact with the first liquid to form the interface therebetween, wherein the first and second liquids are non miscible and have different optical indexes.     
     
     
       59. A method of changing the focus of a variable focus lens according to  claim 58 , wherein the first and second liquids have substantially the same density.