Low height imaging system and associated methods

• US 20060209292A1
• Filed: 09/14/2005
• Published: 09/21/2006
• Est. Priority Date: 09/14/2004
• Status: Active Grant

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: OmniVision CDM Optics, Inc.
• Inventors: Dowski, Edward Raymond Jr., Kubala, Kenneth Scott, Silveira, Paulo E.X., Cormack, Robert H.
• Granted Patent: US 7,453,653 B2
• Time in Patent Office: Days
• US Class Current: 356/121
• CPC Class Codes: G02B 13/003 having two lenses
• 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 13/22 Telecentric objectives or lens systems
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G02B 3/0087 with index gradient
• CPC Class Codes: G02B 5/1885 Arranged as a periodic array
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14632 Wafer-level processed structures
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 25/6153 for colour signals

Abstract

Low height imaging systems may include one or more optical channels and a detector array. Each of the optical channels may be associated with one or more detectors of the array, have one or more optical components and a restrictive ray corrector, and be configured to direct steeper incident angle field rays onto the detectors. Alternatively, each of the optical channels may be associated with at least one detector, and have an aspheric GRIN lens. Another low height imaging system has an array of detectors and a GRIN lens having a surface with wavefront coding and configured to direct steeper incident angle field rays onto more than one of the detectors. One method forms a lens with wavefront coding. The method includes positioning a lens in a mold; and curing material onto a surface of the lens to form an aspheric surface of the lens with wavefront coding.

Claims

1. A low height imaging system, comprising:

one or more optical channels and a detector array, each of the optical channels (a) associated with at least one detector of the array,(b) having one or more optical components and a restrictive ray corrector, and (c) configured to direct steeper incident angle field rays onto the at least one detector.

2. The low height imaging system of claim 1, wherein the optical channels mount directly to the detector array.

3. The low height imaging system of claim 1, wherein the optical channels consist of a single optical channel and the detector array consists of a single detector array.

4. The low height imaging system of claim 1, wherein the optical channels comprise a plurality of optical components and the detector array comprises of a plurality of detector arrays.

5. The low height imaging system of claim 1, the optical channels being formed lithographically.

6. The low height imaging system of claim 1, the optical components comprising a lenslet array wherein each lenslet of the array is part of one channel.

7. The low height imaging system of claim 1, wherein the restrictive ray corrector comprises a GRIN lens.

8. The low height imaging system of claim 7, further comprising a correction plate positioned between the GRIN lens and the detector.

9. The low height imaging system of claim 1, wherein an array of GRIN lenses formed as a stack forms the restrictive ray corrector for each of the channels.

10. The low height imaging system of claim 1, wherein each of the optical channels comprises aspheric optical structure such that optical MTF of the imaging system has no zeroes in a passband of the detector.

11. The low height imaging system of claim 10, further comprising a post processor connected with the detector for compensating for effects of the aspheric optical structure.

12. The low height imaging system of claim 10, further comprising a color filter array to filter color for the detector array.

13. The low height imaging system of claim 10, the restrictive ray corrector comprising one or more of a refractive lens, a Fresnel lens and a diffractive element.

14. The low height imaging system of claim 10, wherein an array of restrictive ray correctors formed as a stack comprises the restrictive ray corrector for the optical channels.

15. The low height imaging system of claim 10, each of the chief ray correctors configured to redirect light of a particular color to a specific detector of the detector array.

16. The low height imaging system of claim 10, the detector being non-rectangular, each of the restrictive ray correctors being configured to redirect light into its associated non-rectangular detector.

17. A low height imaging system, comprising:

a detector array; and

a GRIN lens having a surface with wavefront coding and configured to direct steeper incident angle field rays onto a plurality of detectors of the detector array.

18. A low height imaging system, comprising:

a plurality of optical channels; and

a detector array;

each of the optical channels (a) associated with at least one detector of the array and (b) having an aspheric GRIN lens.

19. The low height imaging system of claim 18, an aspheric surface of the aspheric GRIN lens being modified by wavefront coding.

20. The low height imaging system of claim 18, wherein modulation transfer function of each of the optical channels has no zeroes within a passband of the detector array.

21. The low height imaging system of claim 18, further comprising signal processing to provide a final image based upon phase effects induced by the aspheric GRIN lens of each of the channels.

22. A method of forming a lens with wavefront coding, comprising:

positioning a lens in a mold; and

curing material onto a surface of the lens to form an aspheric surface of the lens with wavefront coding.

23. A low height imaging system, comprising:

a block of optically transmissive material having an entrance aperture, an exit aperture and at least one internally reflective surface, wherein a wavefront transmitted through the entrance aperture reflects off of the reflective surface and exits the exit aperture with wavefront coding.

24. The low height imaging system of claim 23, wherein a surface of the block is formed with wavefront coding and comprises one of the entrance aperture and exit aperture.

25. The low height imaging system of claim 23, wherein the reflective surface is aspheric to impart the wavefront coding.

26. The low height imaging system of claim 23, wherein the exit aperture comprises a flat section of the block, for mounting onto a focal plane array.

27. A low height imaging system, comprising:

a plurality of optical channels and a detector array, each of the optical channels associated with at least one detector of the array and having an aspheric restrictive ray corrector, wherein the aspheric restrictive ray corrector preferentially directs color towards particular detectors of the detector array.

28. A photon compensating optical system, comprising:

at least one optical element and an aspheric surface, wherein a non-constant MTF of the system compensates for a range between the object and the optical element.

29. The photon compensating optical system of claim 28, wherein the aspheric surface comprises a surface of the optical element.

30. The photon compensating optical system of claim 28, the aspheric surface having a nonlinear focal length change across its aperture.

31. The photon compensating optical system of claim 28, the aspheric surface having a nonlinear focal length change across its exit pupil.

32. The photon compensating optical system of claim 28, wherein compensates comprises normalizing energy distribution across a focal plane over the range.

33. A restrictive ray corrector, comprising:

an optical element configured for placement adjacent to, or coupling to, a detector array, the optical element forming at least one surface such that field rays within an optical imaging system are directed towards the detector array with an angle of incidence that is closer to a surface normal of the detector array as compared to angle of incidence of field rays incident on the detector array without the optical element.

34. The restrictive ray corrector of claim 33, wherein the optical element is selected as one of a GRIN lens, a refractive lens, a Fresnel lens and diffractive lens.

35. A low height imaging system, comprising:

a first wafer comprising a plurality of detectors; and

a second wafer including a plurality of aspheric optical components such that MTF of the imaging system has no zeros within a passband of a detectors;

the first and second wafer being stacked to form a low height imaging system with a plurality of optical channels, each of the optical channels having at least one optical component and at least one detector.

36. The low height imaging system of claim 35, further comprising a third wafer stacked with the first and second wafer, to provide optical spacing for the low height imaging system.

37. The low height imaging system of claim 35, the optical components comprising a lenslet array.

38. The low height imaging system of claim 35, further comprising a third wafer stacked with the first and second wafer and comprising an array of restrictive ray correctors, each of the restrictive ray correctors configured to direct steeper incident angle field rays onto at least one associated detector.

39. The low height imaging system of claim 38, wherein the aspheric optical components comprise a lenslet array.