Optical random access memory having multiple state data spots for extended storage capacity

• US 5,465,238 A
• Filed: 07/07/1994
• Issued: 11/07/1995
• Est. Priority Date: 12/30/1991
• Status: Expired due to Fees

• Current Assignee: RITEK Corporation
• Original Assignee: Information Optics Corporation
• Inventors: Russell, James T.
• Primary Examiner(s): Nguyen, Viet Q.
• Application Number:
  US08/273,002
• Time in Patent Office: 488 Days
• Field of Search: 359/20, 250/208.2, 365/234, 365/235, 365/120, 365/124, 369/285, 369/116, 369/100
• US Class Current: 365/234
• CPC Class Codes: G11C 11/56 using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency
• CPC Class Codes: G11C 11/5678 using amorphous/crystalline phase transition storage elements
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 13/04 using optical elements ; using other beam accessed elements, e.g. electron or ion beam
• CPC Class Codes: G11C 13/041 using photochromic storage elements G11C13/042 takes precedence
• CPC Class Codes: G11C 7/005 with combined beam-and individual cell access

Abstract

An optical memory is disclosed in which data is stored in an optical data layer capable of selectively altering light such as by changeable transmissivity or polarization. The data is illuminated by controllable light sources and an array of multi-surface imaging lenslets project the image onto a common array of light sensors. Data is organized into a plurality of regions or patches (called pages) in which each page contains a field of data spots that encode multiple states or levels of data by the amount of transmissivity or polarization of that spot. By selective illumination of each data page, one of the lenslets images the selected data page onto the light sensors. Light in the data image pattern strikes different ones of the arrayed light sensors, thereby outputting the multiple levels per spot in the form of electrical data signals that are A/D converted to digital. A special sensor array uses charge coupled devices (CCDs) that provide multiple storage buckets or levels for each photo sensor element to store and output reference level data along with signal data to quantify and normalize the sensor elements. By selectively and sequentially illuminating different ones of the data regions (pages) on the data layer, correspondingly different data spot patterns are imaged by the corresponding lenslets onto the common sensor array, thereby enabling many stored data pages to be retrieved by multiplexing at electro-optical speed.

Claims

1. An optical system comprising:

an optical data means for storing data as light altering characteristics and being organized into a plurality (P) of juxtaposed data regions each having capacity to store (N) data spots, in which at least certain ones of said data spots have a multiplicity of three or more light altering states, and wherein said multiplicity of light altering states are adapted to encode two or more bits of data at each of said certain ones of said data spots;

controllable light source means for selectively illuminating at least one of said data regions of said optical data means;

data imaging lens means having a plurality of juxtaposed lenslets each being formed and arranged in such proximity to and in optical registration with a separate one of said juxtaposed data regions so that the image resolving power thereof is substantially uniform over the field of view of said separate data region to form an image thereof on a common image surface spaced from said data means and lens means;

sensor means having a plurality (S) of juxtaposed light sensor elements arranged at said image surface for sensing data as a light image corresponding to an illuminated data region, said sensor means including light state detection means for detecting at each of said sensor elements said multiplicity of light altering states of said data spots as imaged onto said common image surface; and

data signal output means coupled to said sensor means for outputting data signals representing said two or more bits of data of said data spots of an illuminated and imaged data region.

2. The optical data system of claim 1, further comprising sensor element normalization means for sequentially flashing certain ones of said controllable light source means prior to or after the selective illumination of said separate data regions for creating a sensor level reference, and sensor level output adjustor means for adjusting each sensor element signal level output as a function of said sensor level reference.

11. The optical data system of claim 1 having sensor element normalization means that comprises:

means for reference flashing said controllable light source means;

means for adjusting output levels of said sensor means in response to said reference flashing of said controllable light source means.

12. The optical data system of claim 11 wherein said sensor element normalization means further comprises timing circuit means for timing said reference flashing of said controllable light source means at intervals timed before or after selectively illuminating at least one of said separate regions.

13. The optical data system of claim 11 wherein said sensor element normalization means further comprises multi-bucket charge coupled device array means for storing sensor reference levels in response to said reference flashing of said controllable light source means.

14. The optical data system of claim 11 wherein said sensor element normalization means comprises reference level storing means for storing sensor response levels in response to said sequentially flashing certain ones of said controllable light sources.

15. The optical data system of claim 2, said sensor means comprises charge coupled array means and said sensor level output adjustor means comprises auxiliary storage wells in said charge coupled array means for storing sensor response reference levels in response to said sequentially flashing certain ones of said controllable light source means.

16. The optical data system of claim 1, further comprising bonding means for bonding said optical data means and said data imaging lens means together as a structural and optical unit, thereby maintaining consistent optical registration therebetween.

3. An optical data system comprising:

an optical data means for storing data as light altering characteristics having a density on the order of one data spot per square micron and being organized into a plurality of juxtaposed data regions each adapted to store a field of data spots each of which has 3 or more light altering states for storing more than 1 binary bit of data;

controllable light source means for selectively illuminating at least one of said data regions of said optical data means;

lens means having a plurality of juxtaposed lenslets configured to resolve objects on the order of one micron or less and each arranged proximate and in optical registration with a separate one of said juxtaposed data regions for forming an image of the field of data thereof on a common image surface spaced from said data means and lens means;

sensor means having a plurality of juxtaposed light sensor elements arranged at said image surface for sensing said data as a light image of an illuminated data region, and including means for discriminating between said 3 or more states of each of said data spots; and

data signal output means coupled to said sensor means for outputting data signals representing said data of more than 1 binary bit per data spot of an illuminated and imaged data region.

17. The optical data system of claim 3, further comprising means for structurally bonding said optical data means to said lens means.

4. An optical data system comprising:

an optical data record means for storing data as light altering characteristics and being organized into a plurality (P) of juxtaposed data regions each having capacity to store (N) data spots, in which at least certain ones of said data spots have a multiplicity of light altering states to store two or more bits of data;

controllable light source means for selectively illuminating at least one of said data regions of said optical data means;

data recording means for photo-optically writing data to each of said (N) data spots to store thereat one of said light altering states;

data imaging lens means having a plurality of juxtaposed lenslets each being formed and arranged in such proximity to and in optical registration with a separate one of said juxtaposed data regions so that the image resolving power thereof is substantially uniform over the field of view of said separate data region to form an image thereof on a common image surface spaced from said data means and lens means;

sensor means having a plurality (S) of juxtaposed light sensor elements arranged at said image surface for sensing data as a light image corresponding to an illuminated data region, said sensor means including light state detection means for detecting at each of said sensor elements said multiplicity of light altering states of said data spots as imaged onto said common image surface; and

data signal output means coupled to said sensor means for outputting data signals representing said two or more bits of data of said data spots of an illuminated and imaged data region.

5. The optical data system of claim 4, further comprising sensor element normalization means for sequentially flashing certain ones of said controllable light source means prior to or after the selective illumination of said separate data regions for creating a sensor level reference, and sensor level output adjustor means for adjusting each sensor element signal level output as a function of said sensor level reference.

7. The optical data system of claim 4 having sensor element normalization means that comprises:

means for reference flashing said controllable light source means; and

means for adjusting output levels of said sensor means in response to said reference flashing of said controllable light source means.

8. The optical data system of claim 7 wherein said sensor element normalization means further comprises timing circuit means for timing said reference flashing said controllable light source means at intervals timed before or after said selectively illuminating at least one of said separate regions.

9. The optical data system of claim 7 wherein said means for adjusting output levels of said sensor means comprises means for storing sensor reference levels in response to said reference flashing of said controllable light source means.

10. The optical data system of claim 8 wherein said sensor element normalization means further comprises multi-bucket charge coupled device array means for storing sensor reference levels in response to said reference flashing of said controllable light source means.

6. An optical data recording system comprising:

an optical data means for storing data as light altering characteristics having a density on the order of one data spot per square micron and being organized into a plurality of juxtaposed data regions each adapted to store a field of data spots each of which has from 4 to 64 or more light altering states for storing 2 to 6 or more binary bits of data at each spot; and

data writing means including controlled writing light source and controlled shutter means for writing said 4 to 64 states to each data spot.

18. The optical recording system of claim 6, further comprising data read means having:

controllable read light source means for selectively illuminating at least one of said data regions of said optical data means;

data imaging lens means having a plurality of juxtaposed lenslets each being formed and arranged in such proximity to and in optical registration with a separate one of said juxtaposed data regions so that the image resolving power thereof is substantially uniform over the field of view of said separate data region to form an image thereof on a common image surface spaced from said data means and lens means;

sensor means having a plurality (S) of juxtaposed light sensor elements arranged at said image surface for sensing data as a light image corresponding to an illuminated data region, said sensor means including light state detection means for detecting at each of said sensor elements said multiplicity of light altering states of said data spots as imaged onto said common image surface; and

data signal output means coupled to said sensor means for outputting data signals representing said two to six bits of data of said data spots of an illuminated and imaged data region.

19. The optical data recording system of claim 18, further comprising means for structurally and optically bonding said optical data means to said lens means.

20. The optical recording system of claim 18 wherein said data writing means includes optical means for directing said controlled writing light source through said lens means to write said 4 to 64 states to each said data spot of said optical data means, whereby light for said writing and reading of data pass through said lens means.