Lenslet array systems and methods

• US 5,973,844 A
• Filed: 01/24/1997
• Issued: 10/26/1999
• Est. Priority Date: 01/26/1996
• Status: Expired due to Fees

• Current Assignee: Proxemics Incorporated
• Original Assignee: Proxemics Incorporated
• Inventors: Burger, Robert J.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Mack, Ricky
• Application Number:
  US08/786,752
• Time in Patent Office: 1,005 Days
• Field of Search: 359/621, 359/622, 359/623, 359/624, 359/626
• US Class Current: 359/622
• 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 3/0062 Stacked lens arrays, i.e. refractive surfaces arranged in at least two planes, without structurally separate optical elements in-between
• CPC Class Codes: G02B 3/0068 arranged in a single integral body or plate, e.g. laminates or hybrid structures with other optical elements G02B5/1885, G02B17/002, G02B30/27 take precedence
• CPC Class Codes: H04N 23/30 for generating image signals from X-rays
• 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: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

A stacked array magnifier (SAM) forms a magnified, demagnified or unit image of an object. The SAM includes one or more non-refractive lenslet arrays and one or more refractive lenslet arrays to form a plurality of lenslet channels. Each lenslet channel has at least one refractive lenslet and at least one non-refractive lenslet. SAMs are combined and tiled to form a scaleable display of flat panel displays. Multiple SAMs are used to increase magnification selectively. Hybrid lenslet arrays of the invention are also useable for optical processing and non-imaging applications.

Claims

1. A stacked array magnifier for forming a magnified image of an object, comprising:

one or more non-refractive lenslet arrays and one or more refractive lenslet arrays to form a plurality of lenslet channels, each lenslet channel having at least one refractive lenslet and at least one non-refractive lenslet, the lenslet channels between at least two adjacent arrays being sloped relative to an optical axis between the object and the image, the sloped lenslet channels further from the optical axis having larger slopes than the sloped lenslet channels closer to the optical axis, the slopes providing selective magnification between the object and the image.

2. A magnifier according to claim 1, wherein the lenslet arrays form a stack between a first surface facing the object and a second surface facing the image, the lenslet channels extending further from the optical axis at the first surface and closer to the optical axis at the second surface, thereby providing demagnification of the object at the image.

3. A magnifier according to claim 2, further comprising a solid state focal plane, the focal plane being substantially perpendicular to the optical axis and arranged at the image to receive electromagnetic radiation thereon from the object.

4. A magnifier according to claim 1, wherein the lenslet arrays form a stack between a first surface facing the object and a second surface facing the image, the lenslet channels extending further from the optical axis at the second surface and closer to the optical axis at the first surface, thereby providing magnification of the object at the image.

5. A magnifier according to claim 1, wherein each lenslet channel has a diameter of between about 5 μ

m and 1000 μ

m.

6. A magnifier according to claim 1, wherein each lenslet channel has a diameter of about 168 μ

m.

7. A magnifier according to claim 1, further comprising a macrolens arranged between at least two adjacent arrays, the macrolens being larger than any of the lenslets and providing additional optical power between the object and image.

8. A magnifier according to claim 1, wherein a plurality of lenslet channels contribute to each point in the image.

9. A magnifier according to claim 1, wherein the lenslet channels are constructed and arranged to provide a magnification ratio of less than about 8:

1 between the object and the image, and further comprising a second stacked array magnifier for providing secondary magnification of the object to a secondary image along the optical axis, the second stacked array magnifier having one or more secondary diffractive lenslet arrays and one or more secondary refractive lenslet arrays, the secondary lenslet arrays of the second magnifier forming a plurality of secondary lenslet channels, each secondary lenslet channel having a substantially linear lenslet channel axis with a predefined slope relative to the optical axis, the secondary lenslet channels further from the optical axis having larger slopes than secondary lenslet channels closer to the optical axis, the slopes of the secondary channels providing a magnification ratio of less than about 8;

1 between the image and the secondary image, the magnifiers acting in concert to image the object to the secondary image with a magnification ratio that is less than about 64;

1.

10. A magnifier according to claim 1, wherein the lenslet arrays are transmissive to electromagnetic radiation in a wavelength range selected from the group of ultraviolet, visible and infrared radiation.

11. A magnifier according to claim 10, further comprising a CCD array arranged at the image and substantially perpendicular to the optical axis so as to collect the visible electromagnetic radiation from the object.

12. A magnifier according to claim 1, wherein the lenslet arrays are transmissive to infrared electromagnetic radiation.

13. A magnifier according to claim 1, wherein the lenslet arrays are formed of material selected from the group of plastic, semiconductor, and glass.

14. A magnifier according to claim 1, wherein at least one refractive lenslet array operates to form an intermediate image of the object and within the stacked array, and further comprising a field stop located at the intermediate image to limit the field of view of one or more lenslet channels.

15. A magnifier according to claim 1, wherein at least one refractive lenslet array operates to form an intermediate image of the object and within the stacked array, and further comprising a lyot stop located at the intermediate image to reduce cross-talk from out-of-field radiation.

16. A magnifier according to claim 1, wherein the lenslet arrays are transmissive to visible electromagnetic radiation between about 540 and 580 nm.

17. A magnifier according to claim 1, wherein the lenslet arrays are transmissive to visible electromagnetic radiation corresponding to the wavelenghts of phosphor and are substantially non-transmissive to radiation outside of the wavelengths.

18. A magnifier according to claim 1, wherein the non-refractive lenslet array is optimized to achieve diffraction efficiencies within a selected waveband.

19. A magnifier according to claim 18, wherein the non-refractive lenslet array comprises a diffractive lenslet array that is optimized with a blaze grating angle.

20. A magnifier according to claim 18, wherein the non-refractive lenslet array comprises a diffractive lenslet array that is optimized with a blaze grating angle to provide peak diffraction efficiency at phosphor emission wavelengths.

21. A magnifier according to claim 1, wherein each lenslet channel comprises an array of three lenslets at each lenslet array, each of the three lenslets being transmissive to a unique RBG color such that substantially any color can be transmitted along each channel, each of the non-refractive lenslets being optimized for optical efficiency corresponding to the RBG color associated with its channel.

22. A magnifier according to claim 1, wherein all lenslets within at least one array are substantially identical.

23. A magnifier according to claim 1, wherein the lenslet arrays form a stack between a first surface facing the object and a second surface facing the image, each channel axis extending substantially parallel to the optical axis, thereby providing unit magnification of the object at the image.

24. A magnifier according to claim 1, wherein each of the refractive lenslets is substantially identical to other refractive lenslets.

25. A magnifier according to claim 1, wherein each of the non-refractive lenslets are diffractive and are substantially identical to other diffractive lenslets.

26. A magnifier according to claim 1, wherein each lenslet channel forms an image of part of the object, the lenslets being constructed and arranged so as to produce overlapping images with adjacent lenslets so as to provide a continuous and non-inverted image of the object.

27. A magnifier according to claim 1, wherein each lenslet channel forms an image of part of the object, the lenslets being constructed and arranged so as to produce an interlaced image.

28. A magnifier according to claim 1, wherein each lenslet channel forms an inverted image of part of the object, the lenslet channels being constructed and arranged so as to produce an array of discrete images of the object.

29. A magnifier according to claim 1, wherein each lenslet channel forms an erect image of part of the object, the lenslet channels being constructed and arranged so as to produce an array of discrete images of the object, the array of discrete images being substantially non-overlapping with adjacent images for collection by a solid state sensor.

30. A magnifier according to claim 1, wherein each lenslet channel forms an erect image of part of the object, the lenslet channels being constructed and arranged so as to produce an array of discrete images of the object, the array of discrete images being overlapping so as to produce a substantially continuous image of the object.

31. A magnifier according to claim 1, further comprising one or more optical coatings on one or more of the lenslet arrays to improve optical transmission through one or more lenslet channels.

32. A magnifier according to claim 1, wherein the lenslet arrays form a stack between a first surface facing the object and a second surface facing the image, the lenslet channels being constructed and arranged to form an intermediate image at a intermediate image plane between the first and second surfaces, and further comprising a stop for one or more of (a) reducing stray light, (b) reducing crosstalk, (c) improving modulation transfer function efficiency, and (d) improving contrast transfer function efficiency of the image, the baffling being located at about the intermediate image plane.

33. A magnifier according to claim 32, wherein the stop is within a blur distance from the intermediate image plane, the blur distance defining a distance within which the image is not degraded be a wavefront error greater than about 1/4λ

.

34. A magnifier according to claim 1, wherein the lenslet arrays form a stack between a first surface facing the object and a second surface facing the image, and further comprising masking material arranged within the stack to reduce stray light transmission from the object to the image.

35. A magnifier according to claim 34, wherein the masking material is formed on a surface of at least one of the lenslet arrays.

36. A magnifier according to claim 35, wherein the masking material is arranged between at least two refractive lenslets.

37. A magnifier according to claim 35, wherein the masking material is arranged between at least two non-refractive lenslets.

38. A magnifier according to claim 34, wherein the masking material reduces stray light cross-talk to less than about 10% of all of the electromagnetic radiation transmitted from the object and to the image.

39. A magnifier according to claim 1, wherein the lenslet arrays form a stack between a first surface facing the object and a second surface facing the image, wherein each of the lenslets of the first surface have a field of view, the fields of view of the first surface lenslets being substantially edge-to-edge with the other fields of view, at the object, so that a substantially continuous image is achieved.

40. A magnifier according to claim 1, wherein the lenslet arrays form a stack between a first surface facing the object and a second surface facing the image, wherein each of the lenslets of the first surface have a field of view, the fields of view of the first surface lenslets being overlapping with the other fields of view so that a substantially continuous image is achieved.

41. A magnifier according to claim 1, wherein the lenslet arrays form a stack between a first surface facing the object and a second surface facing the image, wherein at least one of the arrays forms an intermediate image of the object between the first and second surfaces, and further comprising a field stop to limit the field of view of at least one lenslet channel.

42. A magnifier according to claim 1, wherein each of the lenslet channels is constructed and arranged so as have a lenslet f-number such that the overall f-number of the magnifier is less than the lenslet f-number.

43. A magnifier according to claim 22, wherein each of the lenslet channels is constructed and arranged so as have an f-number of f/1 or greater such that the overall f-number of the magnifier is less than about f/1.

44. A magnifier according to claim 1, wherein each of the non-refractive lenslets is a diffractive lenslet include means for creating diffraction orders of electromagnetic radiation transmitted between the object and the image, the orders being sufficient to provide greater than approximately 90% efficiency.

45. A magnifier according to claim 1, further comprising means for improving resolution of the object such that the image has a modulation transfer function of greater than about 10% at image frequencies greater than about 500 lp/ mm.

46. A magnifier according to claim 1, further comprising means for improving resolution of the object such that the image has a modulation transfer function of greater than about 10% at image frequencies greater than about 500 lp/mm.

47. A magnifier according to claim 46, wherein the means for improving resolution includes at least one refractive optical surface having an aspheric shape.

48. A magnifier according to claim 1, further comprising means for reducing distortion within the image to less than about 2%.

49. A magnifier according to claim 1, wherein the means for reducing distortion comprises edge lenslets having more or less power than other lenslets within the same array, the edge lenslets being adjacent to one or more edges of the magnifier to compensate for pincushion, barrel or petzval distortion.

50. A magnifier according to claim 1, wherein the non-refractive lenslet array comprises one or more of the following:

a diffractive lenslet array, a holographic lenslet array, a phase modulating array and a index modulating surface array.

51. A magnifier according to claim 1, further comprising one or more of a spatial filter and an apodizing filter.

52. A magnifier according to claim 51, wherein the spatial filter comprises an array of stops with different diameters.

53. A magnifier according to claim 1, further comprising at least one lenslet array of planar refractive surfaces.

54. A magnifier according to claim 1, wherein the refractive and non-refractive lenslet arrays include, in combination, means for affecting one or more of the following image characteristics:

modulation transfer function, aberration, throughput efficiency, color correction, and uniformity.

55. A magnifier according to claim 1, wherein the refractive and non-refractive lenslet arrays include, in combination, means for creating image distortion selectively.

56. A magnifier according to claim 1, wherein at least one of the arrays comprises a plurality of tiled arrays, each of the tile arrays acting in concert to optically function as a single array.

57. A magnifier according to claim 56, wherein each of the tile arrays has a clear aperture extending substantially over 100% of the tile array such that the plurality of tile arrays seamlessly combine as a single array without substantially affecting the image.

58. A magnifier according to claim 1, wherein each of the arrays comprises a plurality of lenslet arrays forming a tiled array arranged substantially perpendicular to the optical axis, each lenslet array within the tiled array acting substantially in concert as a single lenslet array, the tiled arrays forming the plurality of lenslet channels as a composite tiled array imager.

59. A magnifier according to claim 58, further comprising means for forming an intermediate image between at least two tiled arrays, and further comprising a field stop for limiting the field of view of at least one channel.