Optical recording using an agglomerating recording medium which changes reflectivity upon recording

An optical digital data record for use with a focused beam of playback radiation of a given frequency and a first playback intensity and also for recording with a focused beam of recording radiation of said given frequency and a second higher recording intensity adapted to write one or more information "bits" at selected sites, said record comprising the combination of:

• support means including a reflective surface portion;
• a first thickness of spacer material exhibiting good thermal insulation properties and being substantially transparent to radiation at said frequency, this material disposed on said surface portion;
• a "semi-continuous" deposit of information material of minimal mass disposed on said spacer material, and exhibiting some absorptivity, some reflectivity and considerable transmissivity at said given frequency, the information material being so selected and so deposited, in minimal mass, as to be "agglomerated" under said recording intensity and so alter reflectance from said information deposit under said play back beam at the bit sites, yet without ablating or otherwise expelling the material at the bit site;
• reflectance values being arranged to so differ that the as-written record will exhibit a given minimum signal-to-noise ratio during playback with said playback beam at said first intensity.

A record for non-deformational, non-ablating recording of "transition bits" on an information deposit thereon with low-power laser write-beams of prescribed wavelength, the record comprising:

• a substrate disk including a prescribed reflector surface exhibiting high reflectivity at said wavelength;
• a spacer layer overlying said surface;
• a semi-continuous deposit of agglomerate material" on the spacer layer and comprising said information deposit;
• this agglomerate material being formulated and applied as a minimum mass whereby, in combination with said spacer layer and reflector surface, the agglomerate material exhibits a first "agglomerated" reflectivity at the "transition-bit" sites which have been subjected to the write-beam and exhibits a second, significantly contrasting reflectivity elsewhere;
• yet without ablating or being otherwise expelled under said write beam.

A novel optical digital record means for use with a radiant energy recording system employing a recording laser providing a write beam of a given frequency and relatively low power, the record means comprising the combination of:

• a substrate;
• a layer of reflector material exhibiting high reflectivity at said given frequency, said layer overlying a surface of said substrate;
• a dielectric thickness on the reflector material, this thickness equal to an integer multiple of the quarter-wavelength of the laser light output passing therethrough and exhibiting relative transparency to the beam at said given frequency, and
• a non-continuous, minimal mass deposit of agglomerate material on the dielectric, this deposit exhibiting significant reflection and greater transmission absorption at said given frequency, while being adapted to "agglomerate" under said beam;
• wherein the antireflectivity of said dielectric thickness minimizes reflective energy loss and its reflectivity minimizes energy loss into said substrate, this dielectric thickness causing light reflected by said reflector to be out of phase with light reflected at the surface of the deposit thereby effecting an enhancement of the write-sensitivity of the record means;
• said agglomerate material being selected and deposited so as to agglomerate and shift in reflectivity when subjected to the recording beam, yet without being ablated or grossly expelled by it.

An optical record means for non-deformational, non-ablative recording of "transition bits" on an information region thereof, with low-energy laser write beams of prescribed wavelength, this record means comprising:

• a substrate including a prescribed reflector surface exhibiting high reflectivity at said wavelength;
• a spacer layer overlying said surface;
• and
• a thin, discontinuous minimum-mass deposit of gold overlying this spacer layer and comprising said information layer, the deposit-gold being formulated and applied in sufficiently discontinuous fashion whereby, in combination with said spacer layer and reflector surface, the deposit-gold will exhibit an "agglomeration" change in morphology-reflectance when subjected to said write beam, this being characterized by an associated first written-reflectivity, with the layer exhibiting a second, significantly-contrasting, virgin-reflectivity elsewhere.

An improved digital data recording system comprising:

• record means including a prescribed non-continuous recording region of agglomerate material adapted for recording of "bits" thereon by exposure of the bit site to a prescribed radiation beam of prescribed wavelength and energy such as to "coagulate" and significantly alter reflectance, yet without ablating the material, such that those "bits" may readily be read-out by related playback radiation means and yield adequate signal contrast;
• and
• recording means including a radiation source means adapted to present this recording beam to so write the "bits" as such reflectance transitions;
• scan means adapted to translate said record means relative to said recording means along prescribed recording paths.

An improved archival digital data recording system comprising:

• disk record means including a non-continuous deposit of low-mass, non-ablative archival record material adapted for recording of "bits" thereon by a prescribed radiation beam of prescribed wavelength serving to "coagulate" and significantly alter deposit-reflectance, such that those "bits" may readily be read-out by related radiational playback means and yield adequate signal contrast;
• recording means including a radiation source means adapted to present such a recording beam to so "write" the "bits" as such "reflectance changes", the intensity of this beam being kept to a minimum;
• and
• scan means adapted to translate said record means relative to said recording means along prescribed recording paths.

An optical recording method for use with a record means having a major surface coated with a multiplicity of layers including a minimum mass of agglormerating archival metal deposited to be non-continuous, a subjacent spacer thickness overlying a metallic mirror layer of high reflectivity under recording radiation, the recorded bits being adapted for detection with prescribed read-out means, this method comprising the steps of:

• focusing a light beam upon this metal deposit;
• and
• moving a succession of bit-regions of the metal deposit recording surface relative to the path of said focused light beam;
• while causing the intensity of said focused light beam to alternate between a first high recording level and a second lower read-back level in accordance with information to be recorded;
• whereby to selectively write by inducing "agglomeration" of the metal, with associated change in reflectance at the bit regions.