Rca Inc.

William J Burke

Allen Bloom

Robert Alfred Bartolini

Michael Ettenberg

Henry Kressel

Alan E Bell

Daniel Louis Ross

William Phillips

Brown F Williams

David L Staebler

Ping Sheng

An ablative optical recording medium comprises a substrate coated with a light reflecting coating of passivated aluminum which in turn is coated with a light absorbing ablative layer. During recording, portions of the light absorbing layer are ablated, or vaporized, by a modulated focussed light beam, thereby exposing portions of the reflective layer. Information is recorded in the form of a reflective-antireflective pattern.

Method of recording an ablative optical recording medium

An optical recording medium comprises a light reflecting material which is coated with a light absorbing layer and overcoated with a thin, amorphous, coherent layer of an optically transparent and chemically and thermally stable material such as silicon dioxide. During recording, portions of the light absorbing layer are ablated by a modulated focussed light beam, thereby exposing portions of the reflecting layer while leaving the overcoat layer intact. Information is recorded in the form of a reflective-antireflective pattern. Dust particles and other surface contaminants can be wiped or washed off the recording medium without damage to the light absorbing layer.

Thin protective overcoat layer for optical video disc

An ablative recording medium comprises a substrate coated with a light reflecting coating which in turn is coated with a light absorptive layer selected from the group consisting of lead phthalocyanine, chloroaluminum phthalocyanine, vanadyl phthalocyanine, stannic phthalocyanine and chloroaluminum chlorophthalocyanine. During recording, portions of the dye layer are ablated or vaporized by an intensity modulated focussed light beam, thereby exposing portions of the reflective layer and recording video information as a reflective-antireflective pattern.

Ablative optical recording medium

In an optical memory device, such as an optical video disk, an injection laser is used as the source of the light, as the detector of the light reflected from the memory element and as the detector for controlling the proper focus of the light on the memory element. The light reflected from the memory element is fed back into the injection laser and variations in certain characteristics of the injection laser, such as the optical output at constant current, the electrical current through the laser at constant voltage and the voltage drop across the laser at constant current, are used to read the memory device and to maintain the focus.

Optical memory with injection laser as light source and detector

A recording medium comprises a substrate coated with a light reflecting layer which in turn is coated with a light absorbing layer selected from the group consisting of Pt complexes of bis-(dithio-.alpha.-diketones) which have the formula: ##STR1## wherein R is a phenyl or substituted phenyl group. During recording, portions of the absorbing layer are ablated, vaporized or melted by an intensity-modulated, focussed light beam, thereby exposing portions of the reflective layer and recording video information as a reflective-antireflective pattern.

Optical recording medium

A moveable mask with a pin hole therethrough is disposed between a source of an object beam and a holographic recording medium. The pin hole limits the angular range of rays of the object beam transmitted to the medium, thereby preventing intermodulation distortion caused by rays of the object beam that have large angles therebetween. The mask may be moved to cause all of the rays of the object beam to pass through the pin hole, whereby a hologram is recorded.

Recording a phase hologram having reduced intermodulation distortion

Single crystal electro-optic material useful for recording phase holograms comprises lithium niobate or lithium tantalate doped with iron and silicon.

Crystals for recording phase holograms

Organic volume phase holographic recording medium comprising an .alpha.-diketone in an acrylic polyester polymer is desensitized by exposing the medium to desensitizing light after recording is complete. This inactivates the .alpha.-diketone and prevents damage to the medium during readout.

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Princeton Junction, NJ, United States of America

William J Burke