Apparatus for recording digital data on an archival optical data storage medium using low power radiation

Claim 2

A record blank for use over relatively long archival life with a recording radiation source providing a write beam at a given frequency and relatively low write-energy, this blank comprising in combination: a substrate having a recording portion exhibiting prescribed optical and thermal characteristics at the given frequency; and a prescribed information layer overlying said portion of said substrate, this layer comprised of a "transition material" and exhibiting a prescribed absorptivity and "virgin-reflectivity" at the given frequency and being adapted to be shifted to a read-out reflectivity on reception of said write-beam corresponding to information to be recorded on prescribed "bit-sites" thereof; said "transition material" being selected and applied so that said beam may so alter said material reflectivity in the course of recording, with the material at each so-recorded bit-site so changing significantly in reflectivity yet without melting or deformation thereof; while also providing good read-out contrast by comparison with the non-recorded areas exhibiting said virginal-reflectivity.

Claim 3

The combination as recited in claim 1, wherein said substrate recording portion is anti-reflective and where said information layer material is deposited just sufficient in depth to render a "first minimum reflectance" as the virginal-reflectivity.

Claim 4

The combination as recited in claim 2, wherein said information layer is arranged and adapted to be so "switched" in reflectivity characteristic when written-upon by said write-beam without deformation thereof and without forming noise-producing "ridges".

Claim 5

The combination as recited in claim 2 as adapted for a high bit density disc record blank for computer information storage.

Claim 6

The combination as recited in claim 2, wherein the anti-reflective portion comprises a spacer means disposed on reflector means, these functioning to support the information layer, this layer having a thickness such as to be partly transmissive to the write beam at said frequency and which thickness is so related to the thickness of the spacer means and to the optical properties of the spacer and reflector means as to, with the information layer, establish a "substantially anti-reflective" condition as said virgin-reflectivity for the record blank at the given frequency.

Claim 7

The combination as recited in claim 5, wherein said information layer, said spacer means and said reflector means are combined into a "tri-layer" structure.

Claim 8

The combination as recited in claim 1, wherein the information layer is comprised of gold.

Claim 9

The combination as recited in claim 1, wherein the information layer is substantially comprised of gold alone.

Claim 10

The combination as recited in claim 1, wherein the information layer is comprised of a gold alloy.

Claim 11

The combination as recited in claim 9, wherein the information layer is comprised of gold and lead.

Claim 12

The combination as recited in claim 9, wherein the information layer is comprised of gold and tin.

Claim 13

The combination as recited in claim 2, wherein the anti-reflective portion comprises a spacer means disposed on reflector means, these functioning to support the information layer, this layer having a thickness such as to be partly transmissive to the write beam at said frequency and which thickness is so related to the thickness of the spacer means and to the optical properties of the spacer and reflector means as to, with the information layer, establish a "substantially anti-reflective" condition as said virgin-reflectivity for the record blank at the given frequency; said information layer, said spacer means and said reflector means being combined into a "tri-layer" structure; and wherein the information layer is comprised of gold; said gold being vapor-deposited to a depth corresponding with "first minimum reflectance".

Claim 14

The combination as recited in claim 12, wherein said substrate comprises an aluminum disc with smoothing layer on which a reflective means is deposited as a metallic film.

Claim 15

The combination as recited in claim 13, wherein a light-transmissive thermally insulative dielectric spacer layer is applied on said reflector film, wherein said information layer is deposited on said spacer layer and also has a protective overcoat layer applied thereon.

Claim 18

The combination as recited in claim 15 wherein said information layer is arranged and adapted to be so "switched" in reflectivity characteristic when written-upon by said write-beam without deformation thereof and without forming noise-producing "ridges".

Claim 19

The combination as recited in claim 16, wherein said information layer is covered with a defocusing overcoat.

Claim 20

A record blank, 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 recording intensity adapted to write information "bits", said second intensity being greater than said first intensity yet being insufficient to melt the associated informational layer, said record blank 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 layer of informational material of a given transition- thickness disposed on said spacer material, and exhibiting some absorptivity, some reflectivity and considerable, more transmissivity at said given frequency, the spacer thickness being such as to induce minimum reflectance from said information layer under said playback beam except at the "bit sites" whereat said recording beam is adapted to so heat said information material there as to induce maximum reflectance there under said playback beam; yet without melting the material at the bit site; these 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.

Claim 21

A record blank, 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 recording intensity adapted to write information "bits", said second intensity being greater than said first intensity yet being insufficient to melt the associated informational layer, said record blank 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 layer of informational material of a given transition- thickness disposed on said spacer material, and exhibiting some absorptivity, some reflectivity and considerable, more transmissivity at said given frequency, the spacer thickness being such as to induce minimum reflectance from said information layer under said playback beam except at the "bit sites" whereat said recording beam is adapted to so heat said information material there as to induce maximum reflectance there under said playback beam; yet without melting the material at the bit site; these 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.

Claim 22

A record blank in accordance with claim 18, wherein the support means is a rotatable disc.

Claim 23

The combination as recited in claim 19, where the spacer thickness comprises a suitable glass and the information material comprises gold or an alloy thereof.

Claim 24

A record blank in accordance with claim 20 wherein said disc is formed of aluminum with a reflective surface subjacent said spacer thickness.

Claim 25

A record blank for use with a low-power recording laser beam for playback with a related playback laser beam, both beams operating at a given wavelength, said record blank comprising, in combination: a substrate having a light reflective surface, said surface exhibiting high reflectivity at said wavelenth; a thickness of spacer-insulator material exhibiting high transparency to said wavelength and overlying said substrate surface; an information layer of "transition-material" exhibiting certain reflectivity absorption but greater transmissivity at this wavelength, while being selected, deposited and arranged so the reflectivity thereof is significantly altered by said recording beam, yet without being melted or deformed thereby.

Claim 26

A record blank for use with a low-power recording laser beam for playback with a related playback laser beam, both beams operating at a given wavelength, said record blank comprising, in combination: a substrate having a light reflective surface, said surface exhibiting high reflectivity at said wavelenth; a thickness of spacer-insulator material exhibiting high transparency to said wavelength and overlying said substrate surface; an information layer of "transition-material" exhibiting certain reflectivity absorption but greater transmissivity at this wavelength, while being selected, deposited and arranged so the reflectivity thereof is significantly altered by said recording beam, yet without being melted or deformed thereby.

Claim 27

The combination as recited in claim 22, wherein said spacer-insulator thickness is such that the laser illumination at the surface of the information layer at said wavelength is normally substantially out-of-phase with, and thus cancelled-out by illumination reflected by said reflective surface.

Claim 28

A record blank for non-deformational, non-melting recording of "transition bits" on an information layer thereof with low-power laser write-beams of prescribed wavelength, the blank comprising: a substrate including a prescribed reflector surface exhibiting high reflectivity at said wavelength; a spacer layer overlying said surface; a layer of "transition material" overlying the spacer layer and comprising said information layer; this transition material being formulated and applied to a depth whereby, in combination with said spacer layer and reflective surface, the information layer exhibits a first reflectivity at the "transition- bit" sites which have been subjected to the write-beam and exhibits a second, significantly contrasting reflectivity elsewhere; yet without melting under said write beam.

Claim 29

A record blank for non-deformational, non-melting recording of "transition bits" on an information layer thereof with low-power laser write-beams of prescribed wavelength, the blank comprising: a substrate including a prescribed reflector surface exhibiting high reflectivity at said wavelength; a spacer layer overlying said surface; a layer of "transition material" overlying the spacer layer and comprising said information layer; this transition material being formulated and applied to a depth whereby, in combination with said spacer layer and reflective surface, the information layer exhibits a first reflectivity at the "transition- bit" sites which have been subjected to the write-beam and exhibits a second, significantly contrasting reflectivity elsewhere; yet without melting under said write beam.

Claim 30

A record blank in accordance with claim 24, wherein said substrate is in the form of a disc with at least one metallic reflector film means thereon constituting said reflector surface.

Claim 31

The combination as recited in claim 24 where the spacer layer comprises a thermally-insulative transparent dielectric whose depth, in conjunction with the reflector film means, constitutes an "anti-reflective" substrate for said "transition material", and wherein the "transition material" is deposited only to a depth corresponding with "initial minimum reflectance" of said laser radiation at said wavelength.

Claim 32

The combination as recited in claim 24 where the substrate comprises an aluminum disc, and the "transition material" is covered with a defocusing overcoat.

Claim 33

The combination as recited in claim 27 where the transition material includes gold.

Claim 34

The combination as recited in claim 28 where transition material is pure gold.

Claim 35

A novel record blank for use with a radiant energy recording system employing a recording laser providing light beam of a given frequency and relatively low power, the record blank comprising the combination of: a substrate; a layer of material exhibiting high reflectivity at said given frequency, said layer overlying a surface of said substrate; a first coating, of a thickness equal to an integer multiple of the quarter-wavelength of the laser light output passing therethrough, exhibiting light transparency at said given frequency, said first coating overlying said layer; and a second transition coating exhibiting significant reflection and greater transmission absorption at said given frequency, said second coating overlying said first coating; wherein the antireflectivity of said first coating minimizes energy loss due to reflection, the reflectivity of said layer minimizes energy loss into said substrate and the thickness of said first coating causes light reflected by said layer to be out of phase with light reflected at the surface of the second coating thereby effecting an enhancement of the sensitivity of the record blank and Th° insulation; said transition coating being adapted to shift in reflectivity when subjected to the recording beam. without being melted by it.

Claim 36

A novel record blank for use with a radiant energy recording system employing a recording laser providing light beam of a given frequency and relatively low power, the record blank comprising the combination of: a substrate; a layer of material exhibiting high reflectivity at said given frequency, said layer overlying a surface of said substrate; a first coating, of a thickness equal to an integer multiple of the quarter-wavelength of the laser light output passing therethrough, exhibiting light transparency at said given frequency, said first coating overlying said layer; and a second transition coating exhibiting significant reflection and greater transmission absorption at said given frequency, said second coating overlying said first coating; wherein the antireflectivity of said first coating minimizes energy loss due to reflection, the reflectivity of said layer minimizes energy loss into said substrate and the thickness of said first coating causes light reflected by said layer to be out of phase with light reflected at the surface of the second coating thereby effecting an enhancement of the sensitivity of the record blank and Th° insulation; said transition coating being adapted to shift in reflectivity when subjected to the recording beam. without being melted by it.

Claim 37

The combination as recited in claim 30 wherein the transition coating is comprised of gold.

Claim 38

The combination in accordance with claim 30 wherein said substrate is in the form of a disk and wherein said light reflective surface comprises a metal layer deposited on a major surface of said disk.

Claim 39

The combination as recited in claim 32 wherein the transition coating is overlaid by a de-focusing protective overcoat on the order of one to a few mils thick.