Keith K Kang

US Patent:

54727596, Dec 5, 1995

Filed:

Dec 16, 1993

Appl. No.:

8/168733

Inventors:

Wenpeng Chen - Bethesda MD
Shekhar Guha - Baltimore MD
Terrance L. Worchesky - Columbia MD
Kenneth J. Ritter - Sykesville MD
Maher E. Tadros - Ellicott City MD
Keith Kang - Ellicott City MD

Assignee:

Martin Marietta Corporation - Bethesda MD

International Classification:

B32B 300

US Classification:

428 651

Abstract:

An optical memory material includes a two-photon storage component which can be written from a first to a second state in response to WRITE light, mixed with a signal component which fluoresces by one-photon absorption only at the written locations in response to READ light. The storage material may be a fulgide. The memory material may also include a frequency upconversion material to aid writing. Writing is performed by a spatial light modulator (SLM) with a dynamic focussing system, for concentrating sufficient power at WRITE locations for nonlinear two-photon absorption. Crosstalk is avoided during simultaneous writing in some embodiments, by spacing the individual WRITE beams apart by an integer number of inter-beam spacings, so that non-adjacent datels are written simultaneously in a "paragraph," and the non-written areas are written at a different time with different paragraphs. The memory material may be translated relative to the SLM to access different paragraphs, or accessed by an electronically sparsed SLM. Reading uses a sheet of READ light traversing the pages of written material to cause the signal component to fluoresce, and imaging the fluorescent pattern onto a detector array.

US Patent:

60458887, Apr 4, 2000

Filed:

May 12, 1995

Appl. No.:

8/440280

Inventors:

Wenpeng Chen - Bethesda MD
Shekhar Guha - Baltimore MD
Terrance L. Worchesky - Columbia MD
Kenneth J. Ritter - Sykesville MD
Maher E. Tadros - Ellicott City MD
Keith Kang - Ellicott City MD

Assignee:

Lockheed Martin Corporation - Bethesda MD

International Classification:

B32B 300

US Classification:

428 641

Abstract:

An optical memory material includes a two-photon storage component which can be written from a first to a second state in response to WRITE light, mixed with a signal component which fluoresces by one-photon absorption only at the written locations in response to READ light. The storage material may be a fulgide. The memory material may also include a frequency upconversion material to aid writing. Writing is performed by a spatial light modulator (SLM) with a dynamic focussing system, for concentrating sufficient power at WRITE locations for nonlinear two-photon absorption. Crosstalk is avoided during simultaneous writing in some embodiments, by spacing the individual WRITE beams apart by an integer number of inter-beam spacings, so that non-adjacent datels are written simultaneously in a "paragraph," and the non-written areas are written at a different time with different paragraphs. The memory material may be translated relative to the SLM to access different paragraphs, or accessed by an electronically sparsed SLM. Reading uses a sheet of READ light traversing the pages of written material to cause the signal component to fluoresce, and imaging the fluorescent pattern onto a detector array.