OPTICAL ZOOM LENS WITH TWO LIQUID LENSES

• US 20160202455A1
• Filed: 08/20/2013
• Published: 07/14/2016
• Est. Priority Date: 08/20/2013
• Status: Abandoned Application

• Current Assignee: Knowles GmbH (Knowles Corporation), Optotune AG (Optotune Switzerland AG)
• Original Assignee: Knowles GmbH (Knowles Corporation), Optotune AG (Optotune Switzerland AG)
• Inventors: ASCHWANDEN, Manuel, BUEELER, Michael, SALT, Martin
• Application Number:
  US14/912,929
• Publication Number:
  US 20160202455A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 13/0065 having a beam-folding prism or mirror
• CPC Class Codes: G02B 13/0075 having an element with variable optical properties
• CPC Class Codes: G02B 13/009 having zoom function
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/0062 by controlling the dispersion of a lens material, e.g. adapting the relative partial dispersion
• CPC Class Codes: G02B 3/14 of variable focal length

Abstract

Optical zoom system (1) for imaging an object plane (100) onto an imaging plane (200), e.g. for a smartphone camera, and comprising two liquid lenses (10, 20) followed by a fixed correction lens (30, 50, 60), the liquids having an Abbe number greater than 60.

Claims

1. An optical system (1) for imaging an object plane (100) to an imaging plane (200), the optical system comprising

said object plane (100),

said imaging plane (200),

a first tunable lens (10) arranged between said object plane (100) and said imaging plane (200), said first tunable lens (10) comprising

a first fixed container (11) made of a rigid material,

a first deformable membrane (12) made of an elastic material, and

a first fluid (15) enclosed by at least said first container (11) and said first membrane (12),

a second tunable lens (20) arranged between said first tunable lens (10) and said imaging plane (200), said second tunable lens (20) comprising

a second fixed container (21) made of a rigid material,

a second deformable membrane (22) made of an elastic material, and

a second fluid (25) enclosed by at least said second container (21) and said second membrane (22),

at least one fixed correction lens (30,40, 50,60) made of a rigid material and arranged between said second tunable lens (20) and said imaging plane (200),

wherein an Abbe number of each of said first fluid (15) and of said second fluid (25) is larger than 60, in particular larger than 80.

4. The optical system (1) of claim 1, wherein at least for one combination of a focal length (f1) of said first tunable lens (10) and a focal length (f2) of said second tunable lens (20), said optical system (1) is structured to image parallel light rays from said object plane (100) to a focal point (201) in said imaging plane (200).

5. The optical system (1) of any of claim 1, wherein a distance between said object plane (100) and said first tunable lens (10) is smaller than 30 mm, in particular smaller than 20 mm, and

wherein at least for one combination of a focal length (f1) of said first tunable lens (10) and a focal length (f2) of said second tunable lens (20), said optical system (1) is structured to image diverging light rays from said object plane (100) to a focal point (201) in said imaging plane (200).

6. The optical system (1) of claim 1, wherein said optical system (1) is structured to provide a continuous plurality of zoom levels and a continuous plurality of focus positions.

7. The optical system (1) of claim 1,

wherein said second membrane (22) of said second tunable lens (20) comprises a second region (22a) oriented towards said imaging plane (200),

wherein said second container (21) of said second tunable lens (20) is oriented towards said object plane (100), and

in particular wherein said first membrane (12) of said first tunable lens (10) comprises a or said first region (12a), and

wherein said first region (12a) of said first membrane (12) of said first tunable lens (10) and said second region (22a) of said second membrane (22) of said second tunable lens (20) are structured to assume a convex shape and a concave shape.

8. The optical system (1) of claim 7 wherein, at least in a first zoom-level of said optical system (1), said first region (12a) assumes a convex shape and said second region (22a) assumes a concave shape.

9. The optical system of claim 7, wherein, at least in a second zoom-level of said optical system (1), said first region (12a) assumes a concave shape and said second region (22a) assumes a convex shape.

10. The optical system (1) of claim 1, further comprising at least one actuator (70), in particular two actuators (70, 71), particularly of the group of

an electrostatic actuator,

an electromagnetic actuator,

an electroactive polymer actuator

a piezo actuator, and

a fluid pump actuator,

wherein at least a or said first region (12a) of said first membrane (12) of said first tunable lens (10) and at least a or said second region (22a) of said second membrane (22) of said second tunable lens (20) are structured to be deformed by said at least one actuator (70) such that a or said focal length (f1) of said first tunable lens (10) and a or said focal length (f2) of said second tunable lens (20) are changeable by means of said actuator (70).

11. The optical system (1) of claim 1, wherein said optical system (1) comprises at least 3, in particular at least 4, particularly exactly 4, fixed correction lenses (30,40,50,60) made of a rigid material, and in particular wherein said fixed correction lenses (30,40,50,60) are arranged between said second tunable lens (20) and said imaging plane (200).

12. The optical system (1) of claim 11, wherein an optical surface, in particular all optical surfaces, of said fixed correction lenses (30,40,50,60) has a minimal absolute radius of curvature value of 2 mm or more.

13. The optical system (1) of claim 11, wherein said correction lenses (30,40, 50,60) are arranged between said second tunable lens (20) and said imaging plane (200), and

wherein an optical surface (30a) of a correction lens (30) which is arranged closest to said second tunable lens (20) has a smaller best fit radius of curvature value than any other optical surfaces of said correction lenses (30,40,50,60).

14. The optical system (1) of claim 1, wherein at least one fixed correction lens (60) is adapted to correct a field curvature of said optical system (1).

15. The optical system (1) of claim 1, wherein said optical system (1) is structured to assume at least a tele-zoom-level configuration and a wide-zoom-level configuration, and

wherein a maximum chief ray angle at an axial position between said second tunable lens (20) and said imaging plane (200) in said tele-zoom-level configuration is equal to a maximum chief ray angle at an axial position between said second tunable lens (20) and said imaging plane (200) in said wide-zoom-level configuration within a range of ±

2.5°

.

16. The optical system (1) of claim 1, wherein said first container (11) of said first tunable lens (10) is meniscus shaped and/or wherein said second container (21) of said second tunable lens (22) is meniscus shaped.

17. The optical system (1) of claim 1, wherein an optical front surface (11a) of said first container (11) of said first tunable lens (10) has a convex shape and

wherein an optical back surface (11b) of said first container (11) of said first tunable lens (10) has a concave shape, and

in particular wherein said optical front surface (11a) is oriented towards said object plane (100) and wherein said optical back surface (11b) is oriented towards said first membrane (12) of said first tunable lens (10).

18. The optical system (1) of claim 1, wherein an optical front surface (21a) of said second container (21) of said second tunable lens (20) has a convex shape and

wherein an optical back surface (21b) of said second container (21) of said second tunable lens (20) has a concave shape, and

in particular wherein said optical front surface (21a) is oriented towards said object plane (100) and said optical back surface (21b) is oriented towards said second membrane (22) of said second tunable lens (20).

19. The optical system (1) of claim 1, further comprising an aperture stop (90), in particular a round aperture stop (90), wherein said aperture stop (90) is particularly arranged between said first tunable lens (10) and said second tunable lens (20).

20. The optical system (1) of claim 1,

wherein said first tunable lens (10) additionally comprises a first fixed lens shaper (13) and/or

wherein said second tunable lens (20) additionally comprises a second fixed lens shaper (23).

21. The optical system (1) of claim 19 wherein an axial distance between said first lens shaper (13) and said aperture stop (90) is equal to an axial distance between said second lens shaper (23) and said aperture stop (90) within a range of ±

50%, in particular ±

20%.

22. The optical system (1) of claim 1, further comprising

a folding prism (80) for diverting an optical axis (A) of said optical system (1).

23. The optical system (1) of claim 22, wherein said folding prism (80) has a non-quadratic, in particular a rectangular, footprint.

24. The optical system of claim 22, wherein said folding prism (80) comprises a cut edge (81).

25. The optical system (1) of claim 22, wherein at least a or said first region (12a) of said first membrane (12) of said first tunable lens (10) directly faces said folding prism (80).

26. The optical system (1) of claim 22, wherein a or said optical front surface (21a) of said second container (21) of said second tunable lens (20), said optical front surface (21a) being oriented towards said object plane (100), directly faces said folding prism (80) or wherein only one or more apertures and/or aperture stops (90) are arranged between said second container (21) and said folding prism (80).

27. The optical system (1) of claim 19, wherein an axial distance between said aperture stop (90) and said folding prism (80) is smaller than or equal to 1.5 times a smallest lateral radius of said aperture stop (90).

28. The optical system (1) of claim 1, wherein said first tunable lens (10) directly faces said object plane (100) or

wherein a protection element (300), in particular only a protection element (300), particularly a cover glass (300), is arranged between said first tunable lens (10) and said object plane (100).

29. The optical system (1) of claim 1, wherein a or said first fluid (15) of said first tunable lens (10) comprises a liquid, in particular consists of a liquid and/or

wherein a or said second fluid (25) of said second tunable lens (20) comprises a liquid, in particular consists of a liquid.

30. The optical system (1) of claim 1, wherein a or said optical front surface (11a) of said first container (11) of said first tunable lens (10) is non-spherical.

31. The optical system (1) of claim 1, wherein a or said optical back surface (11b) of said first container (11) of said first tunable lens (10), said optical back surface (11b) being oriented towards said first membrane (12) of said first tunable lens (10), is substantially spherical and/or

wherein a or said optical back surface (21b) of said second container (21) of said second tunable lens (20), said optical back surface (21b) being oriented towards said second membrane (22) of said second tunable lens (20), is substantially spherical.

32. The optical system (1) of claim 1, wherein a or said second region (22a) of said second membrane (22) of said second tunable lens (20) is structured to be symmetrically deflectable around a zero position.

33. A cellular phone (999) or a tablet computer comprising

an optical system (1) of claim 1, and

an imaging sensor (202) arranged in an imaging plane (200) of said optical system (1).

2. An optical system (1) for imaging an object plane (100) to an imaging plane (200), the optical system comprising

said object plane (100),

said imaging plane (200),

a first tunable lens (10) arranged between said object plane (100) and said imaging plane (200), said first tunable lens (10) comprising

a first fixed container (11) made of a rigid material, and

a first deformable membrane (12) made of an elastic material, and

a second tunable lens (20) arranged between said first tunable lens (10) and said imaging plane (200), said second tunable lens (20) comprising

a second fixed container (21) made of a rigid material, and

a second deformable membrane (22) made of an elastic material,

at least one fixed correction lens (30,40, 50,60) made of a rigid material and arranged between said second tunable lens (20) and said imaging plane (200),

wherein said first container (11) of said first tunable lens (10) is oriented towards said object plane (100), and

wherein at least a first region (12a) of said first membrane (12) of said first tunable lens (10) is oriented towards said imaging plane (200).

3. The optical system (1) of claim 2

wherein said first tunable lens (10) comprises a first fluid (15) enclosed by at least said first container (11) and said first membrane (12),

wherein said second tunable lens (20) comprises a second fluid (25) enclosed by at least said second container (21) and said second membrane (22), and

wherein an Abbe number of each of said first fluid (15) and of said second fluid (25) is larger than 60, in particular larger than 80.