Variable focus lens

• US 20050113912A1
• Filed: 01/24/2003
• Published: 05/26/2005
• Est. Priority Date: 02/14/2002
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Snoeren, Rudolph, Feenstra, Bokke Johannes, Kuiper, Stein, Stallinga, Sjoerd, Hendriks, Bernardus
• Granted Patent: US 7,126,903 B2
• Time in Patent Office: Days
• US Class Current: 623/6.130
• CPC Class Codes: A61B 1/0019 characterised by variable lenses
• CPC Class Codes: G02B 13/0075 having an element with variable optical properties
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G02B 3/14 of variable focal length
• CPC Class Codes: G11B 2007/0013 for carriers having multiple discrete layers
• CPC Class Codes: G11B 7/1378 Separate aberration correction lenses; Cylindrical lenses to generate astigmatism; Beam expanders
• CPC Class Codes: G11B 7/13925 active, e.g. controlled by electrical or mechanical means

Abstract

A variable focus lens comprising a first fluid (A) and a second, non-miscible, fluid (B) in contact over a meniscus. A first electrode (2) separated from the fluid bodies by a fluid contact layer (10), and a second electrode (12) in contact with the first fluid to cause an electrowetting effect whereby the shape of the meniscus is altered. The fluid contact layer has a substantially cylindrical inner wall.

Claims

1. A variable focus lens including

a substantially cylindrical fluid chamber having a cylinder wall, the fluid chamber including a first fluid (A) and an axially displaced second fluid (B), the fluids being non-miscible, in contact over a meniscus (14) and having different indices of refraction,

a fluid contact layer (10) arranged on the inside of the cylinder wall,

a first electrode (2) separated from the first fluid and second fluid by the fluid contact layer,

a second electrode (12) acting on the second fluid,

the fluid contact layer having a wettability by the second fluid which varies under the application of a voltage between the first electrode and the second electrode, such that the shape of the meniscus varies in dependence on the said voltage,

wherein the wettability of the fluid contact layer by the second fluid is substantially equal on both sides of the intersection of the meniscus with the contact layer when no voltage is applied between the first and second electrodes.

2. A lens according to claim 1, wherein the inner surface of the fluid contact layer has a linear cross-section, and wherein the linear cross section is parallel to the axis of the substantially cylindrical shape of the surface to within 10 degrees.

3. A lens according to claim 1, wherein the first fluid includes an insulating liquid and the second fluid includes a conducting liquid.

4. A lens according to claim 1, wherein the first fluid includes a vapour and the second fluid includes a conducting liquid.

5. A lens according to claim 1, wherein the lens is arranged to produce a meniscus shape which is concave when viewed from the second fluid, the shape becoming less concave at increasing magnitude of voltage applied between the first and second electrodes.

6. A lens according to claim 1, wherein the fluid contact layer is a substantially homogeneous layer of uniform thickness.

7. A lens according to claim 1, wherein said first electrode is substantially cylindrical.

8. A lens according to claim 1, wherein said first fluid has a larger refractive index than said second fluid and wherein the lens is a compound lens comprising at least one fixed lens element (104) providing a positive lens power, such that the compound lens has a positive lens power when the meniscus is convex in relation to the first fluid.

9. An optical device comprising a lens according to claim 1, the device comprising means defining a focusing plane (120) wherein the lens is arranged such that when radiation consisting of parallel rays is input and a non-zero voltage is applied between the first and second electrodes, the radiation is focused on the focusing plane.

10. An image capture device comprising a lens according to claim 1.

11. An optical scanning device for scanning an optical record carrier, comprising a lens according to claim 1.

12. An optical scanning device according to claim 12, wherein said lens is arranged to correct for spherical aberrations arising during the scanning of different information layer depths in optical record carriers being scanned.

13. A method of operating a variable focus lens including a substantially cylindrical fluid chamber having a cylinder wall, the fluid chamber including a first fluid (A) and an axially displaced second fluid (B), the fluids being non-miscible, in contact over a meniscus (14) and having different indices of refraction,

a fluid contact layer (10) arranged on the inside of the cylinder wall,

a first electrode (2) separated from the first fluid and second fluid by the fluid contact layer,

a second electrode (12) acting on the second fluid,

the wettability of the fluid contact layer by the second fluid being substantially equal on both sides of the intersection of the meniscus with the contact layer when no voltage is applied between the first and second electrodes,

the wettability of the fluid contact layer by the second fluid varying under the application of a voltage between the first electrode and the second electrode,

the method comprising controlling the said voltage to change the shape of the meniscus.

14. A method according to claim 13 wherein said method comprises varying said voltage to produce a meniscus shape which is concave when viewed from the second fluid.

15. A method according to claim 13, wherein said method further comprises varying said voltage to produce a meniscus shape which is convex when viewed from second fluid.

16. A method according to claim 15, wherein said meniscus has a contact angle with the fluid contact layer of between 100 and 140 degrees.