Folded optic array camera using refractive prisms

• US 9,541,740 B2
• Filed: 06/17/2015
• Issued: 01/10/2017
• Est. Priority Date: 06/20/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Georgiev, Todor Georgiev
• Primary Examiner(s): KHAN, USMAN A
• Application Number:
  US14/742,285
• Publication Number:
  US 20150370040A1
• Time in Patent Office: 573 Days
• Field of Search: 348/335
• US Class Current: 1/1
• CPC Class Codes: G02B 13/006 at least one element being a compound optical element, e.g. cemented elements
• CPC Class Codes: G02B 13/0065 having a beam-folding prism or mirror
• CPC Class Codes: G02B 13/007 the beam folding prism having at least one curved surface
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
• CPC Class Codes: G02B 5/04 Prisms
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G03B 17/17 with reflectors arranged in beam forming the photographic image, e.g. for reducing dimensions of camera
• CPC Class Codes: G03B 37/04 with cameras or projectors providing touching or overlapping fields of view
• CPC Class Codes: G06T 3/4038 Image mosaicing, e.g. composing plane images from plane sub-images
• CPC Class Codes: H04N 23/45 for generating image signals from two or more image sensors being of different type or operating in different modes, e.g. with a CMOS sensor for moving images in combination with a charge-coupled device [CCD] for still images
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/698 for achieving an enlarged field of view, e.g. panoramic image capture
• CPC Class Codes: H04N 25/41 Extracting pixel data from a plurality of image sensors simultaneously picking up an image, e.g. for increasing the field of view by combining the outputs of a plurality of sensors
• CPC Class Codes: Y10T 29/49119 Brush
• CPC Class Codes: Y10T 29/49828 Progressively advancing of work assembly station or assembled portion of work

Abstract

Aspects relate to a prism array camera having a wide field of view. For example, the prism array camera can use a central refractive prism, for example with multiple surfaces or facets, to split incoming light comprising the target image into multiple portions for capture by the sensors in the array. The prism can have a refractive index of approximately 1.5 or higher, and can be shaped and positioned to reduce chromatic aberration artifacts and increase the FOV of a sensor. In some examples a negative lens can be incorporated into or attached to a camera-facing surface of the prism to further increase the FOV.

Claims

1. A prism array camera for capturing a target image scene, comprising:

a plurality of cameras positioned around a vertical axis of symmetry of the prism array camera, each camera of the plurality of cameras comprising;

an image sensor, and

an optical axis positioned at a first angle relative to the vertical axis of symmetry, the first angle corresponding to an angular value; and

a plurality of prisms, each prism configured to direct a portion of light representing the target image scene toward a corresponding camera of the plurality of cameras at least partially by refraction, each prism comprising;

a first surface positioned orthogonally to the vertical axis of symmetry of the prism array camera, the first surface positioned so that the portion of light representing the target image scene enters the prism through the first surface,

a second surface positioned such that a plane formed by the second surface bisects the first angle between the optical axis of the corresponding camera and the vertical axis of symmetry, and

a third surface, the second surface configured to redirect the portion of light received from the first surface toward the third surface, the third surface positioned such that the portion of light representing the target image scene exits the prism and travels toward the corresponding camera.

2. The prism array camera of claim 1, wherein the prism further comprises an apex at a point of intersection between the first surface and the second surface, and wherein the optical axis of the each camera of the plurality of cameras and the vertical axis of symmetry of the prism array camera system pass through the apex.

3. The prism array camera of claim 1, wherein the third surface is positioned at a second angle relative to the first surface, the second angle corresponding to the angular value.

4. The prism array camera of claim 1, wherein a length of the first surface and a length of the third surface are substantially equal.

5. The prism array camera of claim 1, further comprising a negative lens formed in or affixed to the third surface.

6. The prism array camera of claim 1, further comprising a reflective backing provided on the second surface.

7. The prism array camera of claim 1, wherein a first light folding surface comprises the second surface of the prism, each camera of the plurality of cameras further comprising a secondary light folding surface positioned between the first light folding surface and the image sensor.

8. The prism array camera of claim 7, wherein the secondary light folding surface comprises a reflective surface or an additional prism.

9. The prism array camera of claim 1, wherein each camera of the plurality of cameras further comprises a lens assembly positioned between the third surface of the prism and the image sensor.

10. The prism array camera of claim 1, further comprising a processor configured to combine an image generated from the portion of light representing the target image scene from each of the plurality of cameras into a final image of the target scene.

11. A method of manufacturing a prism array camera, the method comprising:

determining a vertical axis of symmetry of the prism array camera;

positioning a prism assembly such that the vertical axis of symmetry passes through the prism assembly;

positioning at least two cameras on opposing sides of the prism; and

for each camera of the at least two cameras

positioning the camera such that an optical axis of the camera is positioned at a first angle relative to the vertical axis of symmetry, the first angle corresponding to an angular value, and

positioning a refractive prism of the prism assembly such that;

a first surface of the prism is positioned orthogonally to the vertical axis of symmetry, the first surface positioned so that a portion of light representing a target image scene enters the prism through the first surface,

a second surface of the prism is positioned such that a plane formed by the second surface bisects the first angle, the second surface configured to reflect the portion of light received from the first surface toward a third surface of the prism, and

the third surface is positioned such that the portion of light exits the prism through the third surface and travels toward the camera.

12. The method of manufacturing the prism array camera of claim 11, further comprising positioning the third surface of the prism at a second angle relative to the first surface of the prism, the second angle corresponding to the angular value.

13. The method of manufacturing the prism array camera of claim 12, wherein the prism has a first length for the first surface and a second length for the third surface, and wherein the first length is substantially equal to the second length.

14. The method of manufacturing the prism array camera of claim 12, further comprising positioning each of the at least two cameras to receive light representing a portion of a target image scene from the third surface of a corresponding prism.

15. The method of manufacturing the prism array camera of claim 12, further comprising providing a negative lens within or secured to the third surface of the prism.

16. The method of manufacturing the prism array camera of claim 11, further comprising providing a reflective backing on the second surface of the prism.

17. The method of manufacturing the prism array camera of claim 11, further comprising providing a processor in electronic communication with each of the plurality of cameras, the processor configured to combine a plurality of images into a final image of the target image scene, each of the plurality of images received from a corresponding one of the at least two cameras and comprising a representation of the portion of the target image scene received from the third surface of a corresponding prism.

18. The method of manufacturing the prism array camera of claim 11, wherein the first surface and the second surface of the optical element intersect at an apex of the prism, the method of manufacturing the prism array camera further comprising positioning the optical axis of a corresponding one of the plurality of cameras to intersect with the apex of the prism.

19. The method of manufacturing the prism array camera of claim 18, wherein the apex of the prism lies along the vertical axis of symmetry.

20. The method of manufacturing the prism array camera of claim 19, further comprising positioning the prism associated with each of the at least two cameras such that the apex of each prism of the prism assembly is adjacent to the apex of at least one other prism of the prism assembly.

21. A prism assembly for use in an array camera, the prism assembly comprising:

a vertical axis of symmetry; and

a plurality of refractive optical elements each associated with a corresponding one of a plurality of cameras of the array camera and configured to pass a portion of light representing a target image scene toward the corresponding one of the plurality of cameras, each of the plurality of refractive optical elements comprising;

a first surface positioned orthogonally to the vertical axis of symmetry of the array camera, the first surface positioned so that the portion of light representing the target image scene enters the prism through the first surface,

a second surface positioned such that a plane formed by the second surface bisects a first angle between an optical axis of the corresponding one of the plurality of cameras and the vertical axis of symmetry,

a third surface, the second surface configured to redirect the portion of light received from the first surface toward the third surface, the third surface positioned such that the portion of light representing the target image scene exits the prism and travels toward the corresponding one of the plurality of cameras, and

an apex defined by an intersection of the first surface and second surface.

22. The prism assembly of claim 21, further comprising a reflective backing provided on the second surface of each of the plurality of refractive optical elements.

23. The prism assembly of claim 21, wherein the apex of each of the plurality of refractive optical elements is a point positioned along the vertical axis of symmetry.

24. The prism assembly of claim 22, wherein the apex of each of the plurality of refractive optical elements is positioned substantially adjacent to the apex of each other of the plurality of refractive optical elements.

25. The prism assembly of claim 24, wherein the first surfaces of the plurality of refractive optical elements are substantially coplanar.

26. The prism assembly of claim 25, wherein the second surfaces of the plurality of refractive optical elements define a recess within the prism assembly.

27. The prism assembly of claim 21, further comprising a negative lens formed within or affixed to the third surface of each of the plurality of refractive optical elements.

28. The prism assembly of claim 21, wherein each of the plurality of refractive optical elements is manufactured from a substantially transparent material having an index of refraction of approximately 1.5 or higher.

29. An apparatus for capturing images, comprising:

at least two means for capturing a plurality of portions of a target image scene;

means for refracting light representing each portion of the plurality of portions, the means for refracting light positioned between the at least two means for capturing and comprising a set of facets associated with each of the at least two means for capturing, each set of facets arranged in a geometric relationship comprising;

a first facet positioned orthogonally to a vertical axis of symmetry of the means for refracting light, the first facet positioned so that a portion of light representing a target image scene enters the prism through the first facet,

a second facet positioned at a first angle relative to the vertical axis of symmetry, the first angle bisecting an angle formed between an optical axis of one of the at least two means for capturing and the vertical axis of symmetry, the second facet configured to reflect the portion of light received from the first facet toward a third facet, and

the third facet positioned such that the portion of light exits the prism through the third facet and travels toward the one of the at least two means for capturing; and

means for assembling the plurality of portions into a final image of the target image scene.

30. The apparatus of claim 29, wherein the means for refracting light comprises an assembly of a plurality of refractive optical elements, each of the plurality of refractive optical elements having at least the first, second, and third facets arranged in the geometric relationship.