Lenslet array systems and methods

• US 6,124,974 A
• Filed: 03/25/1999
• Issued: 09/26/2000
• 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): MACK, RICKY LEVERN
• Application Number:
  US09/276,896
• Time in Patent Office: 551 Days
• Field of Search: 359/619, 359/621, 359/622, 359/624, 359/625, 359/626
• US Class Current: 359/621
• 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 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• 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. In a method of manufacturing a microlenslet array of the type having a plurality of lenslets formed within a optical substrate having a first planar surface, a second planar surface, and a normal vector that is substantially perpendicular to each surface, the improvement comprising the steps of forming a first lenslet array within the first surface, forming a second lenslet array within the second surface, forming a plurality of lenslet channels between the lenslet arrays wherein each channel includes one lenslet from each of the arrays, the lenslet channels between at least two adjacent arrays having a channel axis vector relative to the normal vector such that the cross product between the channel axis vector and the optical axis vector is greater for lenslet channels further away from a line extending along a center of the substrate and parallel to the normal vector.

2. In a method according to claim 1, a further improvement wherein the step of forming a plurality of lenslet comprises the step of forming lenslets selected from the group of diffractive lenslets, holographic lenslets, phase modulating lenslets, index modulating lenslets, and refractive lenslets.

3. 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.

4. A method according to claim 3, further comprising the step of arranging the channels such that at least two channels contribute to the image of each point of the object.

5. A method according to claim 3, further comprising the step of arranging at least one array so as to produce an intermediate image of the object and between other arrays, and further comprising a field stop located at the intermediate image so as to reduce the field of view of at least one channel.

6. A method of manufacturing a scaleable large screen display from an electronic display of the type having a center and a substantially planar surface with a surface normal perpendicular to the surface, the display of the type selected from the group consisting essentially of an LCD display, a cathode ray tube, and one or more laser diodes, comprising:

selecting a desired magnification of the display;

forming a tiled array of stacked lenslet arrays, the tiled array corresponding to magnification of the display, the stacked arrays within each tiled array operating in concert with every other stacked array within the tiled array so as to operate substantially as a single lenslet array, each stacked lenslet array being formed through the following steps;

forming at least one array of refractive lenslets into a first optical substrate and at least one other array of non-refractive lenslets into a second optical substrate, the non-refractive lenslets being selected from the group consisting essentially of diffractive lenslets, holographic lenslets, phase modulating lenslets, and index modulating lenslets, arranging the arrays into a stack having a plurality of lenslet channels, each of the channels having at least one refractive lenslet and one non-refractive lenslet, and wherein the step of arranging the arrays includes the step of creating a sloped channel axis between at least two arrays and relative to the surface normal,

arranging the tiled arrays to operate in concert such that the sloped channel axis is larger for channels further from the center as compared to channels closer to the center wherein the desired magnification of the display is achieved.

7. A method of manufacturing a stack of lenslet arrays for imaging an object to an image, comprising the steps of:

forming one or more non-refractive lenslet arrays and one or more refractive lenslet arrays, forming a plurality of lenslet channels and arranging the channels such that each lenslet channel has at least one refractive lenslet and at least one non-refractive lenslet, and arranging the lenslets within a channel to achieve a selected magnification between the object and image.

8. A method according to claim 7, further comprising the step of forming at least one of the arrays through one of (a) molding of an optical grade polymer and (b) coextrusion of an optical polymer, with an opaque polymer.

9. A method according to claim 7, further comprising the step of fabricating the lenslets from a negative relief to generate surface features, plus fiducial marks and mechanical assembly features, the negative relief being fabricated into a metal, ceramic or high temperature composite master.

10. A method according to claim 9, further comprising the step of transferring a positive master in glass, semiconductor or crystal material to a ceramic or elastomer template to form a negative mold master.

11. A method according to claim 7, further comprising the step of forming the arrays from different optical materials so as to correct for optical color aberrations.

12. A method according to claim 7, further comprising the step of manufactured at least two of the arrays through replication, including the steps of fabricating a mold from a negative relief of the refractive and non-refractive lenslets, and of fabricating fiducial and mechanical assembly features within the stack.

13. A method according to claim 12, further comprising the step of fabricating the relief from a metal, ceramic or high temperature composite master which is produced by micromachining or by direct forming into a master mold material.

14. A method according to claim 13, further comprising the steps of coating the master with a release agent followed by one of (a) an epoxy, (b) a polymer, (c) an optical quality organic, and (d) a sol gel material to produce a thin sheet of material with lenslet array features, fiducial marks, and mechanical assembly features.

15. A method according to claim 7, further comprising the step of fabricating opaque interstitial areas to provide for stops and to eliminate or reduce optical crosstalk among nearby lenslet channels.

16. A method according to claim 7, further comprising the step of fabricating the lenslet arrays with fiducial features to facilitate alignment and registration of lenslet array channels in Cartesian x-y and rotational coordinates.

17. A method according to claim 16, further comprising the step of locating the fiducial features at one or more of (a) outside of the lenslet clear aperture and (b) interstial to the lenslet array features.

18. A method according to claim 16, further comprising the step of arranging the fiducial features as one or more of (a) a frame around the lenslet array mask, or parts of the lenslet array mask, (b) within interstitial regions to the lenslet array channels, (c) horizontal or vertical lines, sequences of lines, crossed lines, circles, squares, hexagons, other geometrics or combinations of geometric shapes.

19. A method according to claim 16, further comprising the step of arranging fiducial marks such that a Moire pattern is generated upon assembly of the arrays, thereby indicating proper registration.

20. A method according to claim 16, further comprising the step of making the fiducial marks and assembly features out of material used in the masking of the interstitial and surrounding regions of the lenslets.

21. A method according to claim 16, further comprising the step of making the fiducial marks and assembly features as etched features within the array substrate.

22. A method according to claim 16, further comprising the step of making the fiducial marks and assembly features out of mechanical spacers for placement within the stack.

23. A method according to claim 16, further comprising the step of forming the fiducial marks out of one of a material that transforms from a solid to a liquid when subjected to heat or other activation such that a surface tension is created to promote alignment of the stack.

24. A method according to claim 23, further comprising the step of retransforming the material of the fiducial and assembly features back to a solid, thereby bonding the stack together into a monolithic structure.

25. A method according to claim 23, further comprising the step of assembling the stack with the material at one or more of (a) edges of the stack or (b) internal locations of the stack.

26. A method according to claim 16, further comprising the step of immersing the arrays with adhesive for monolithic bonding of the stack.

27. A method according to claim 16, further comprising the step of adding thru-holes within the stack so as to provide for the insertion of micromechanical pins which assist stack assembly and which mechanically tie the stack into a monolithic structure.