High density block oriented solid state optical memories

• US 4,663,738 A
• Filed: 12/04/1984
• Issued: 05/05/1987
• Est. Priority Date: 12/04/1984
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Urbach, John C., Sprague, Robert A.
• Primary Examiner(s): Moffitt, James W.
• Application Number:
  US06/678,145
• Time in Patent Office: 882 Days
• Field of Search: 365/120, 365/121, 365/122, 365/124, 365/10, 365/234, 365/127, 250/216, 250/578, 250/237 R
• US Class Current: 365/127
• CPC Class Codes: G11C 13/04 using optical elements ; using other beam accessed elements, e.g. electron or ion beam
• CPC Class Codes: G11C 7/005 with combined beam-and individual cell access

Abstract

A block oriented solid state optical memory having a distributed data storage architecture comprises a lens array including a plurality of laterally separated lenslets which have numerical apertures selected to cause them to focus essentially diffraction limited images of a photoemitter array in parallel onto laterally displaced sections of a data mask, so that the images optically align with respective photosensors. The lenslets are formed on the first surface of the lens array, and the data mask is supported on or very close to the last surface of the lens array to minimize the scattering of reflected light. An opaque light shield on the first surface of the lens array optically masks the area between the lenslets to eliminate unwanted stray light. Furthermore, in at least some embodiments of the invention, the light shield extends into the apertures of the lenslets to stop them down sufficiently to obtain substantially diffraction limited performance.

Claims

1. In a solid state optical memory having a photoemitter array including a plurality of selectively and individually energizeable photoemitters, a photodetector array including a plurality of photosensors, and a data mask optically interposed between said photoemitter and photodetector arrays;

the improvement comprising

a lens array located between said photoemitter array and said data mask,

said lens array including a plurality of spatially separated lenslets for focusing plural, spatially separated images of said photoemitter array in parallel onto said data mask, said images being optically aligned with respective ones of said photosensors and having sufficient resolution to separately resolve each of said photoemitters, whereby said memory is opticaly partitioned into a plurality of spatially displaced memory sectors and each of said memory sectors is optically subdivided into a plurality of selectively illuminable memory cells,

said lenslets having apertures selected so that said images are essentially diffraction limited, whereby said memory sectors are finely subdivided for the storage of relatively densely compacted data.

2. The improvement of claim 1 wherein

said lenslets are substantially hemispherical and are formed on a first surface of said lens array,

an opague light shield on the first surface of said lens array optically masks areas between said lenslets to eliminate stray light, and

said data mask is adjacent a last surface of said lens array.

3. The improvement of claim 2 wherein

said light shield extends into the apertures of said lenslets to stop them down, thereby causing said lenslets to achieve substantially diffraction limited performance.

4. The improvement of claim 3 wherein

bits of multi-bit data blocks are mapped onto said data mask in accordance with a mapping pattern selected to locate the bits of each of said data blocks in memory cells which are selectively illuminable by a respective one of said photoemitters,

said bits have binary values, and

said data mask has an optical transmission profile patterned in accordance with the values of the bits mapped thereon,

whereby said photosensors accumulate the binary values of the bits of a selected data block whenever one of said photoemitters is selectively energized.

5. The improvement of claim 4 further including

lens means optically interposed between said photoemitter array and said lens array for substantially collimating light emitted by each of said photemitters, thereby correcting for lateral distortion of said images.

6. The improvement of claim 1 wherein

said lenslets are formed on a first surface of said lens array,

said data mask is in intimate contact with a last surface of said lens array, and

said lens array has a substantially uniform optical thickness, so that the apertures of said lenslets are substantially equidistant from said data mask.

7. The improvement of claim 6 wherein

said lenslets are substantially hemispherical, and

said lens array further includes an opague light shield on its first surface for blocking stray light falling between said lenslets.

8. The improvement of claim 7 wherein

said light shield extends into the apertures of said lenslets to stop them down, thereby causing said lenslets to achieve substantially diffraction limited performance.

9. The improvement of claim 8 wherein

bits of multi-bit data blocks are mapped onto said data mask in accordance with a mapping pattern selected to locate the bits of each of said data blocks in memory cells which are selectively illuminable by a respective one of said photoemitters,

said bits have binary values, and

said data mask has an optical transmission profile patterned in accordance with the values of the bits mapped thereon,

whereby said photosensors accumulate the binary values of the bits of a selected data block whenever one of said photoemitters is selectively energized.

10. The improvement of claim 9 further including

lens means optically interposed between said photoemitter array and said lens array for substantially collimating light emitted by each of said photoemitters, thereby correcting for lateral distortion of said images.