Lenslet array systems and methods

• US 6,381,072 B1
• Filed: 07/20/2000
• Issued: 04/30/2002
• Est. Priority Date: 01/23/1998
• Status: Expired due to Fees

• Current Assignee: Proxemics Incorporated
• Original Assignee: Proxemics Incorporated
• Inventors: Burger, Robert J.
• Primary Examiner(s): Mack, Ricky
• Application Number:
  US09/600,662
• Time in Patent Office: 649 Days
• Field of Search: 359/621, 359/622, 359/623, 359/624, 359/625
• US Class Current: 359/622
• CPC Class Codes: G02B 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence
• CPC Class Codes: G02B 27/4277 being separated by an air space
• 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 3/0068 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: G02B 5/1814 structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings G02B5/189 takes precedence

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, 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.

2. A magnifier according to claim 1, wherein the stop comprises an active micro-mechanical actuator with an electronically addressable and adjustable aperture.

3. 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, wherein each of the lenslet channels has an active, electronically addressable, adjustable f-stop, the f-stop comprising one of an actuator assembly, a tunable iris, and a shutter mechanism.

4. 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 lens 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, comprising one or more active, electronically addressable, adjustable MEMS devices for changing the spacing between lenslets in order to change focal properties and magnification.

5. 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, comprising one or more active, electronically addressable micromechanical iris/shutter for one of changing the f-stop of lenslets and of activating/deactivating select lenslet channels.

6. A method of manufacturing a microlens stack having an optical magnification for producing an image of an object along an optical axis, comprising the steps of:

combining at least two refractive lenslet arrays with at least one diffractive lenslet array to form a lenslet array stack with a plurality of lenslet channels, each of the channels having a sloped axis between at least two of the arrays, and arranging the channels such that the cross product between the sloped axis and the optical axis is greater for lenslet channels further from the optical axis as compared to lenslet channels closer to the optical axis, thereby achieving the magnification selectively; and

arranging, between the arrays, one or more active, electronically addressable, actuator mechanisms fabricated into a substrate by microlithographic techniques for one of (a) changing channel f-stops, (b) shuttering lenslet channels, or (c) modulating spacing between arrays.

7. A tiled array image for generating an image of an object along an optical axis between the object and the image:

at least two tiled arrays forming a lenslet array stack arranged substantially perpendicular to the optical axis, each of the tiled arrays formed of a plurality of lenslet arrays including one or more non-refractive lenslet arrays and one or more refractive lenslet arrays, each lenslet array within a tiled array acting substantially in concert as a single lenslet array, the tiled arrays forming a plurality of lenslet channels, each lenslet channel between at least two arrays having a channel axis with a predefined slope relative to the optical axis, the lenslet channels further from the optical axis having larger slopes than lenslet channels closer to the optical axis, the slopes providing demagnification between the object and the image.

8. A tiled image according to claim 7, wherein the non-refractive lenslet arrays comprise one or more of diffractive lenslet arrays, holographic lenslet arrays, phase modulating arrays, and index modulating surface arrays.

9. A tiled image according to claim 7, further comprising means for forming an intermediate image between at least two arrays, and further comprising a field stop for limiting the field of view of at least one channel.

10. Scene generating apparatus, comprising:

a computer for generating signals representative of an selected pattern;

flat panel display means responsive to the signals to display the pattern, the display means having a display center and a normal vector perpendicular to a face of the display means;

a plurality of lenslet arrays formed into a stack having a plurality of lenslet channels, the channels between at least two arrays having a sloped channel axis relative to the surface normal vector, the lenslet arrays being constructed and arranged to generate an image of the pattern on the display means, the cross product of the sloped channel axis and the surface normal vector being larger for channels further from the center as compared to channels closer to the center wherein selective magnification of the image is achieved.

11. Scene generating apparatus according to claim 10, wherein each of the arrays comprises a plurality of tiled lenslet arrays that act substantially in concert as a single optical lenslet array.

12. Scene generating apparatus according to claim 10, wherein the flat panel display comprises a liquid crystal display.

13. Scene generating apparatus according to claim 10, wherein each of the arrays comprises a plurality of tiled lenslet arrays formed into an x,y array that act substantially in concert as a single optical lenslet array.

14. A digital camera, comprising:

a film-formatted camera body and camera lens which generate an image of a scene at an image plane within the camera body and in a format corresponding to 35 mm film;

one or more non-refractive lenslet arrays and one or more refractive lenslet arrays formed into a stack with a first outer surface and a second outer surface, the stack being constructed and arranged to fit within the camera body such that the first surface is at the image plane, the lenslet arrays forming a plurality of lenslet channels which act in concert to form a secondary image that is sized to a solid state focal plane array; and

a solid state focal plane array arranged at the secondary image.

15. A digital camera, comprising:

a solid state imaging device of the type that includes an array of detector pixels responsive to electromagnetic radiation within a range of wavelengths;

a window for protecting the device and for imaging the radiation onto the device, the window having one or more non-refractive lenslet arrays and one or more refractive lenslet arrays formed into a stack, the stack being constructed and arranged over the device and forming a plurality of lenslet channels which act in concert to form an image that is sized to the device.

16. A camera according to claim 15 wherein the lenslet channels are sloped between at least two arrays and relative to a surface normal of the device so as to increase a field of regard of the window.

17. A four-array reimaging system for generating an image of an object along an optical axis, comprising:

a pair of refractive lenslet arrays sandwiched between a pair of diffractive lenslet arrays, the arrays being substantially perpendicular to the optical axis and forming an array of co-registered lenslet channels, each of the lenslet channels having a plurality of refractive lenslets and a plurality of diffractive lenslets.

18. A system according to claim 17, further comprising a plurality of inter-lenslet channel stops, each stop being constructed and arranged to form baffling between adjacent lenslet channels.

19. A system according to claim 17, further comprising a plurality of inter-lenslet channel stops, each stop being constructed and arranged to form one of an aperture stop or field stop along a lenslet channel.

20. A system according to claim 17, further comprising an active actuator mechanism arranged between lenslet arrays as a spacer for one or more of (a) changing camera f-stop, (b) shuttering, and (b) modulating spacing between arrays to change camera focus.

21. A system according to claim 17, wherein each of the arrays comprise a tiled array of sub-arrays, the sub-arrays acting in concert as a single lenslet array.

22. A system according to claim 17, wherein each of the arrays is formed into a separate optical substrate such that the system contains eight surfaces.

23. A system according to claim 17, wherein at least one of the arrays forms an intermediate image between two arrays, and further comprising a field stop arranged at the intermediate image to limit the field of view of one or more channels.

24. A system according to claim 17, further comprising one or more optical baffles located on one or more arrays, or between two arrays, to block stray radiation at the image.

25. A system according to claim 17, wherein at least one of the arrays forms an intermediate image within a substrate of one array, and further comprising means arranged at the intermediate image to limit the field of view of one or more channels.

26. Hybrid lenslet imaging apparatus, comprising an array of lenslet channels, each channel having at least one refractive optical element and at least one non-refractive optical element, the array forming an image of an object plane wherein a plurality of lenslet channels contribute to each point in the object plane.

27. Apparatus according to claim 26, wherein the non-refractive optical elements comprise one or more diffractive lenslets, holographic lenslets, phase modulating lenslets, and index modulating lenslets.

28. Discrete pixel array image relay apparatus, comprising at least one refractive lenslet array and one non-refractive lenslet array, the arrays being constructed and arranged between first and second surfaces to form a plurality of lenslet channels which, in combination, generate an image of a discrete pixel array.

29. Apparatus according to claim 28, wherein the discrete pixel array comprises a discrete light source selected from the group of CCDs, phosphor screens, flat panel displays, LCDs, and one or more laser diodes.

30. Apparatus according to claim 28, further comprising a phosphor surface arranged substantially in contact and adjacent to the first surface, and further comprising a solid state device arranged substantially in contact and adjacent to the second surface, thereby providing reimaging of the phosphor between the first and second surfaces.

31. A compact optical correlator for imaging an object to a solid state detector, comprising:

a first stack and a second stack arranged substantially perpendicular to an axis formed between the object and the detector, each stack having one or more non-refractive lenslet arrays and one or more refractive lenslet arrays, the lenslet arrays forming a plurality of lenslet channels wherein each channel includes one lenslet from each of the other arrays, the first stack generating a Fourier image between the first and second stacks at a filtering plane, the second stack generating an image of the Fourier image such that the object is reimaged onto the detector; and

an optical filter arranged at the filtering plane for selectively filtering electromagnetic energy so as to achieve selected optical processing.