Folded camera lens systems

Patent metadata

Field	Value
Publication number	US-9557627-B2
Application number	US-201414291571-A
Country	US
Kind code	B2
Filing date	May 30, 2014
Priority date	Mar 7, 2014
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

A folded lens system may include multiple lenses with refractive power and a light path folding element. Light entering the camera through lens(es) on a first optical path or axis is refracted to the folding element, which changes direction of the light onto a second optical path or axis with lens(es) that refract the light to form an image plane at a photosensor. At least one of the object side and image side surfaces of at least one of the lens elements may be aspheric. Total track length (TTL) of the lens system may be 16.0 mm or less. The lens system may be configured so that the telephoto ration |TTL/f| is greater than 1.0. Materials, radii of curvature, shapes, sizes, spacing, and aspheric coefficients of the optical elements may be selected to achieve quality optical performance and high image resolution in a small form factor camera.

First claim

What is claimed is:

1. A camera, comprising:
a photosensor configured to capture light projected onto a surface of the photosensor; and
a folded lens system comprising a plurality of optical elements arranged along a first optical axis and a second optical axis of the camera and configured to:
refract light from an object field located in front of the camera along the first optical axis;
redirect the light on to the second optical axis; and
refract the light on the second optical axis to form an image of a scene at an image plane at or near the surface of the photosensor;

wherein the plurality of optical elements includes at least two and at most five refractive lens elements, wherein the refractive lens elements include:
a first refractive lens element on the first optical axis; and
at least one and at most four refractive lens elements on the second optical axis; and

wherein the folded lens system has effective focal length f and total track length TTL, and wherein telephoto ratio |TTL/| of the folded lens system is within a range of 0.8 to 1.2.

2. The camera as recited in claim 1 , wherein, to redirect the light on to the second optical axis, the folded lens system includes a light path folding element configured to reflect the light from the first optical axis on to the second optical axis.

3. The camera as recited in claim 2 , wherein the light path folding element is a prism.

4. The camera as recited in claim 2 , wherein the folded lens system further includes an aperture stop located at or in front of the first refractive lens element or between the first refractive lens element and a reflecting surface of the light path folding element.

5. The camera as recited in claim 4 , wherein the aperture stop is adjustable to provide a focal ratio within a range of 2.4 to 10.

6. The camera as recited in claim 1 , wherein at least one surface of at least one of the refractive lens elements is aspheric.

7. The camera as recited in claim 1 , wherein at least one of the refractive lens elements is composed of a first plastic material, and wherein at least one other of the refractive lens elements is composed of a second plastic material with different optical characteristics than the first plastic material.

8. The camera as recited in claim 1 , wherein at least one of the plurality of optical elements is configured to translate or move along a respective optical axis to adjust focus of the image of the scene at the photosensor.

9. The camera as recited in claim 1 , wherein the photosensor is configured to translate or move along a respective optical axis to adjust focus of the image of the scene at the photosensor.

10. The camera as recited in claim 1 , wherein total track length (TTL) of the folded lens system is 16.0 millimeters or less.

11. The camera as recited in claim 1 , wherein effective focal length f of the folded lens system is within a range of 8.0 millimeters to 14 millimeters, and wherein focal ratio of the folded lens system is within a range of 2.4 to 10.

12. The camera as recited in claim 1 , wherein the plurality of optical elements includes, in order along the first and second optical axes from an object side of the camera to an image side of the camera:
the first refractive lens element on the first optical axis with positive refractive power having a convex object side surface;
a second refractive lens element on the second optical axis;
a third refractive lens element on the second optical axis;
a fourth refractive lens element on the second optical axis; and
a fifth refractive lens element on the second optical axis.

13. The camera as recited in claim 12 ,
wherein focal length f 1 of the first refractive lens element satisfies the condition 0.5<|f 1 /f|<0.8,
wherein focal length f 2 of the second refractive lens element satisfies the condition 0.3<|f 2 /f|<2.0,
wherein focal length f 3 of the third refractive lens element satisfies the condition 0.2<|f 3 /f|<0.6,
wherein focal length f 4 of the fourth refractive lens element satisfies the condition 0.4<|f 4 /f|<1.5, and
wherein focal length f 5 of the fifth refractive lens element satisfies the condition 0.3<|f 5 /f|<3.0.

14. The camera as recited in claim 12 , wherein the plurality of optical elements further includes a prism located between the first refractive lens element and the second refractive lens element and configured to redirect the light from the first optical axis on to the second optical axis.

15. The camera as recited in claim 14 , wherein at least one of the first refractive lens element or the second refractive lens element is combined with the prism to form a single optical element.

16. A folded lens system, comprising:
at least two and at most five refractive lens elements arranged along a folded optical axis of the folded lens system, wherein at least one surface of at least one of the refractive lens elements is aspheric;
wherein the folded lens system has effective focal length f and total track length (TTL), and wherein the folded lens system is adjustable to provide a telephoto ratio |TTL/f| within a range of 0.8 to 1.2; and
wherein at least one of the refractive lens elements is composed of a first material, and wherein at least one other of the refractive lens elements is composed of a second material with different optical characteristics than the first material.

17. The folded lens system as recited in claim 16 , wherein total track length (TTL) of the folded lens system is 16 millimeters or less.

18. The folded lens system as recited in claim 16 , wherein f is within a range of 8.0 millimeters to 14 millimeters.

19. The folded lens system as recited in claim 16 , wherein the folded lens system includes, in order along the folded optical axis from an object side of the folded lens system to an image side of the folded lens system:
a first refractive lens element on a first optical path of the folded optical axis with positive refractive power having a convex object side surface;
a light path folding element configured to redirect light from the first optical path of the folded optical axis on to a second optical path of the folded optical axis;
a second refractive lens element on the second optical path;
a third refractive lens element on the second optical path;
a fourth refractive lens element on the second optical path; and
a fifth refractive lens element on the second optical path.

20. The folded lens system as recited in claim 19 , wherein the light path folding element is one of a mirror or a prism.

21. The folded lens system as recited in claim 19 , wherein the light path folding element is a prism, and wherein at least one of the first lens element or the second lens element is combined with the prism to form a single optical element.

22. A device, comprising:
one or more processors;
one or more cameras; and
a memory comprising program instructions executable by at least one of the one or more processors to control operations of the one or more cameras;
wherein at least one of the one or more cameras is a small form factor camera comprising:
a photosensor configured to capture light projected onto a surface of the photosensor; and
a folded lens system configured to:
refract light from an object field located in front of the camera along a first optical axis;
redirect the light onto a second optical axis; and
refract the light on the second optical axis to form an image of a scene at an image plane at or near the surface

Assignees

• Apple Inc

Inventors

• Mercado Romeo I

Classifications

• G02B13/0045 Primary

  having five or more lenses · CPC title

• G02B13/0065

  having a beam-folding prism or mirror · CPC title

• G02B17/08

  Catadioptric systems {(used in non-imaging applications G02B19/00)} · CPC title

• G02B1/041

  Lenses · CPC title

• G03B17/17 Primary

  with reflectors arranged in beam forming the photographic image, e.g. for reducing dimensions of camera · CPC title