Optical record, and associated recording and reading-out devices

Claim 2

Record readable by means of a monochromatic beam of radiant energy and storing on a data carrier p signals within a single track of constant width, p being an integer at least equal to unity; said signals exhibiting variations in instantaneous amplitude; said data carrier having a non uniform optical characteristic, said characteristic defining fringes within said track, said fringes being directed along the axis of said track and forming p superimposed sets; and at least one of said fringes being continuous along said track; each said set of fringes being respectively associated with each said signal and obeying a distinctive law of spacing along a direction perpendicular to the axis of said track, said law being variable along said axis and transcribing in said track said instantaneous amplitude; said law of spacing being that of a set of interference fringes produced by two monochromatic light point sources arranged on a straight line parallel to the plane of said data carrier and perpendicular to the axis of said track; one of said point sources being fixed and the other vibrating along said straight line with an elongation proportional to said instantaneous amplitude.

Claim 3

Record as claimed in claim 1, wherein said data carrier has a non uniform transparency, said non uniform transparency being said non uniform optical characteristic.

Claim 4

Record as claimed in claim 1, wherein said data carrier has a non uniform reflectivity, said non uniform reflectivity being said non uniform optical characteristic.

Claim 5

Record as claimed in claim 1, wherein said data carrier has two faces; one at least of said faces carrying a reflective relief having a non uniform wavy profile; and wavy profile being said non uniform optical characteristic.

Claim 6

Record as claimed in claim 1, wherein said data carrier is transparent and presents a non uniform thickness; said non uniform thickness being said non uniform optical characteristic.

Claim 7

Record as claimed in claim 1, wherein said data carrier is transparent and presents a non uniform refractive index, said non uniform refractive index being said non uniform optical characteristic.

Claim 8

Record as claimed in claim 1, wherein said data carrier takes the shape of a disk, said disk having two parallel faces and a rotation centre; at least one track being inscribed on at least one said face and along a constant-pitch spiral; said signals being stored along said track.

Claim 9

Record as claimed in claim 1, wherein said data carrier has two faces, at least one transparent layer and one flat mirror; said layer underlying said face and said mirror underlying said layer.

Claim 10

Record as claimed in claim 8, wherein said non uniform optical characteristic is the non uniform thickness of said layer.

Claim 11

Record as claimed in claim 8, wherein said non uniform optical characteristic is the non uniform refractive index of said layer.

Claim 12

Record as claimed in claim 8, wherein said non uniform optical characteristic is the non uniform transparency of said layer.

Claim 13

Holographic recorder for recording a record readable by means of a monochromatic beam of radiant energy and storing on a data carrier p signals within a single track of constant width, p being an integer at least equal to unity; said signals exhibiting variations in instantaneous amplitude; said data carrier having a non uniform optical characteristic, said characteristic defining fringes within said track, said fringes being directed along the axis of said track and forming p superimposed sets; and at least one of said fringes being continuous along said track; each said set of fringes being respectively associated with each said signal and obeying a distinctive law of spacing along a direction perpendicular to the axis of said track, said law being variable along said axis and transcribing in said track said instantaneous amplitude; each said set of fringes, upon illumination of said track by said monochromatic beam, reconstructing a diffracted spherical wave having a phase centre; said phase centre describing a straight line under the displacement of said track; the position of said phase centre along said straight line being representative of said instantaneous amplitude of said signal, said holographic recorder comprising: means for providing a continuous displacement of said data carrier; a radiation source; optical means for forming from said source a spherical carrier wave and p spherical object waves; and optical-mechanical means for deflecting respectively said p spherical object waves; said optical-mechanical means being controlled by said p signals; the centres of said waves respectively describing p straight lines perpendicular to said displacement, the abscisse of each said centre on each said line being respectively proportional to the instantaneous amplitude of said p signals; means for providing a rectangular interference zone located in said data carrier, said rectangular zone being very narrow in the direction of said displacement.

Claim 14

Holographic recorder for recording a record readable by means of a monochromatic beam of radiant energy and storing on a data carrier p signals within a single track of constant width, p being an integer at least equal to unity; said signals exhibiting variations in instantaneous amplitude; said data carrier having a non uniform optical characteristic, said characteristic defining fringes within said track, said fringes being directed along the axis of said track and forming p superimposed sets; and at least one of said fringes being continuous along said track; each said set of fringes being respectively associated with each said signal and obeying a distinctive law of spacing along a direction perpendicular to the axis of said track, said law being variable along said axis and transcribing in said track said instantaneous amplitude; each said set of fringes, upon illumination of said track by said monochromatic beam, reconstructing a diffracted spherical wave having a phase centre; said phase centre describing a straight line under the displacement of said track; the position of said phase centre along said straight line being representative of said instantaneous amplitude of said signal, said holographic recorder comprising: means for providing a continuous displacement of said data carrier; a radiation source; optical means for forming from said source a spherical carrier wave and p spherical object waves; and optical-mechanical means for deflecting respectively said p spherical object waves; said optical-mechanical means being controlled by said p signals; the centres of said waves respectively describing p straight lines perpendicular to said displacement, the abscisse of each said centre on each said line being respectively proportional to the instantaneous amplitude of said p signals; means for providing a rectangular interference zone located in said data carrier, said rectangular zone being very narrow in the direction of said displacement.

Claim 15

Holographic recorder as claimed in claim 12, wherein a single plane, parallel to said recording medium, contains the centres of said carrier and object waves.

Claim 16

Holographic recorder as claimed in claim 12, wherein said radiation source is a coherent radiation source.

Claim 17

Optical reader for reading out a record readable by means of a monochromatic beam of radiant energy and storing on a data carrier p signals within a single track of constant width, p being an integer at least equal to unity; said signals exhibiting variations in instantaneous amplitude; said data carrier having a non uniform optical characteristic, said characteristic defining fringes within said track said fringes being directed along the axis of said track and forming p superimposed sets; and at least one of said fringes being continuous along said track; each said set of fringes being respectively associated with each said signal and obeying a distinctive law of spacing along a direction perpendicular to the axis of said track, said law being variable along said axis and transcribing in said track said instantaneous amplitude; each said set of fringes, upon illumination of said track by said monochromatic beam, reconstructing a diffracted spherical wave having a phase centre; said phase centre describing a straight line under the displacement of said track; the position of said phase centre along said straight line being representative of said instantaneous amplitude of said signal, said reader comprising: means for communicating a motion to said data carrier; a quasi-punctiform quasi-monochromatic light source; optical means for forming from said source said monochromatic beam p read-out channels, each channel including a linearly variable transparency plate and photodetector means; said monochromatic beam illuminating said track for providing p said diffracted spherical waves respectively travelling through said optical channels, said photodetector means being positioned at the end of said channels for collecting said diffracted spherical waves, said plates intercepting said diffracted spherical waves between said track and said photodetector means.

Claim 18

Optical reader for reading out a record readable by means of a monochromatic beam of radiant energy and storing on a data carrier p signals within a single track of constant width, p being an integer at least equal to unity; said signals exhibiting variations in instantaneous amplitude; said data carrier having a non uniform optical characteristic, said characteristic defining fringes within said track said fringes being directed along the axis of said track and forming p superimposed sets; and at least one of said fringes being continuous along said track; each said set of fringes being respectively associated with each said signal and obeying a distinctive law of spacing along a direction perpendicular to the axis of said track, said law being variable along said axis and transcribing in said track said instantaneous amplitude; each said set of fringes, upon illumination of said track by said monochromatic beam, reconstructing a diffracted spherical wave having a phase centre; said phase centre describing a straight line under the displacement of said track; the position of said phase centre along said straight line being representative of said instantaneous amplitude of said signal, said reader comprising: means for communicating a motion to said data carrier; a quasi-punctiform quasi-monochromatic light source; optical means for forming from said source said monochromatic beam p read-out channels, each channel including a linearly variable transparency plate and photodetector means; said monochromatic beam illuminating said track for providing p said diffracted spherical waves respectively travelling through said optical channels, said photodetector means being positioned at the end of said channels for collecting said diffracted spherical waves, said plates intercepting said diffracted spherical waves between said track and said photodetector means.