Mirror utilized in magneto-optical readout system to eliminate fresnel effect

Claim 2

A Kerr effect read-out system, for reading binary data magnetically recorded on a metallic ferromagnetic layer, comprising in combination; a source of linearly polarized light; means including a ferromagnetic metallic mirror for directing said light on to the layer in which the data to be read out are recorded; conversion means for deriving signals proportional to the intensity of light reflected from said layer; and means for magnetically saturating said mirror along a predetermined direction.

Claim 3

A Kerr effect read-out system, for reading binary data magnetically recorded on a metallic ferromagnetic layer, comprising in combination; a source of linearly polarized light; means including a ferromagnetic metallic mirror for directing said light on to the layer in which the data to be read out are recorded; conversion means for deriving signals proportional to the intensity of light reflected from said layer; and means for magnetically saturating said mirror along a predetermined direction.

Claim 4

A Kerr effect read-out system, for reading binary data magnetically recorded on a metallic ferromagnetic layer, comprising in combination; a source of linearly polarized light; means including a ferromagnetic metallic mirror for directing said light on to the layer in which the data to be read out are recorded; conversion means for deriving signals proportional to the intensity of light reflected from said layer; and means for magnetically saturating said mirror along a predetermined direction.

Claim 5

A Kerr effect read-out system as defined by claim 1 wherein said mirror material saturating means includes means for modulating the magnetization by oscillating it between reverse conditions of saturation and wherein a synchronous phase detector means is connected to receive both the electric signal derived from the light reflected from the layer after analysis thereof and the electric signal controlling the said magnetization modulation of said mirror material magnetic saturating means.

Claim 6

A Kerr effect read-out system as defined by claim 2 wherein said modulating means is arranged to control simultaneously the magnetization of all the material of said mirror.

Claim 7

A Kerr effect read-out system as defined by claim 2 wherein said modulating means is arranged to control the magnetization of the material of said mirror in predetermined portions in step-by-step fashion.

Claim 8

A Kerr effect read-out system as defined by claim 2 in which the recording layer is fixed with respect to the light reflected from said mirror and in which means are inserted between said mirror and the layer for distributing the light reflected by the mirror on said layer in as many secondary light beams as there are memory points in the layer and in which said conversion means is a mosaic of photo responsive elements.

Claim 9

A Kerr effect read-out system as defined by claims wherein each one of said secondary light beams is of such size as to span over a plurality of memory points in the layer.

Claim 10

A Kerr effect read-out system as defined by claim 5 wherein said light distributing means includes means for scanning the recording layer with said secondary beams.

Claim 11

A Kerr effect read-out system as defined by claim 2 wherein the recording layer has multiple information recording tracks movable within the incidence plane of light reflected from said mirror said system including means inserted between said mirror and the moving layer for forming and directing on the layer a plurality of secondary light beams a number of which is related to the number and grouping relation of the information recording tracks, and at least one column of photo responsive conversion elements positioned to receive the light from said secondary beams followiNg reflection from the layer and analysis thereof.

Claim 12

A Kerr effect read-out system as defined by claim 8 wherein each one of such secondary light beams is formed by reflection of part of the primary linearly polarized beams on a portion of said mirror controlled by a portion of said magnetization modulating means distinctly activated with respect to other portions magnetizing other portions of said mirror.

Claim 13

A Kerr effect read-out system as defined by claim 9 wherein said synchronous detector circuit means comprise as many phase detector circuits as there are recording tracts spanned over by each one of said secondary light beams and means selectively connecting said phase detector circuits to the outputs of groups of photo responsive conversion elements positioned to receive light from said secondary beams after reflection from the tracks and analysis thereof, in accordance with selective magnetization of portions of said reflecting mirror.