Optical arrangement and a reading apparatus including detection of data elements diffractive along entire extent

Claim 2

An arrangement for reading an optically readable light reflective carrier on which data is stored in the form of diffractive data elements which are deviations from a smooth reference surface but not holes through the carrier, said data elements each having a width of at most 2 microns, said data elements forming tracks with clearance bands in the reference surface therebetween, comprising: illumination means for projecting a concentrated light spot onto said carrier and said data elements, said light spot substantially occupying the width of a track being read in order to obtain diffraction of light along the entire length of each of said data elements; an optical arrangement for collecting light reflected from said carrier in such a manner that the maximum light energy is received when the projected light spot impinges on the reference surface and the minimum light energy is received when the projected light spot impinges on a data element, the optical arrangement being configured and positioned such that a part of the light diffracted by said data elements is not collected by said optical arrangement; and detection means receiving the collected light for providing a data readout signal.

Claim 3

A reading arrangement according to claim 1 wherein said detection means comprises first and second photodetector elements.

Claim 4

A reading arrangement according to claim 2 wherein said detection means comprises means for summing a signal from said first and second photodetector elements to provide the data readout signal.

Claim 5

A reading arrangement according to claim 2 wherein said detection means comprises means for obtaining a difference signal between said first and second photodetector elements to provide a signal for controlling track registration.

Claim 6

A reading arrangement according to claim 4 wherein said detection means comprises means for moving at least a portion of said optical arrangement in response to said signal for controlling track registration.

Claim 7

A reading arrangement according to claim 1 wherein said optical arrangement includes a semi-transparent mirror.

Claim 8

The arrangement according to claim 1, wherein said illumination means comprises a lens and wherein said optical arrangement also comprises said lens.

Claim 11

A system according to claim 8 wherein said detection means comprises first and second photodetector elements.

Claim 12

A system according to claim 9 wherein said detection means comprises means for summing a signal from said first and second photodetector elements to provide the data readout signal.

Claim 13

A system according to claim 9 wherein said detection means comprises means for obtaining a difference signal between said first and second photodetector elements to provide a signal for controlling track registration.

Claim 14

A system according to claim 11 wherein said detection means comprises means for moving at least a portion of said optical arrangement in response to said signal for controlling track registration.

Claim 15

A system according to claim 9 wherein said optical arrangement includes a semi-transparent mirror.

Claim 16

A system according to claim 23 wherein said substrate is a disk.

Claim 17

A system according to claim 8 wherein said pitch is two to three times the width of a data element.

Claim 18

A system according to claim 8 wherein said tracks are rectilinear.

Claim 19

A system according to claim 8 wherein said substrate is a tape.

Claim 20

A system according to claim 8 wherein said tracks of data elements are turns of a spiral.

Claim 21

A system according to claim 8 wherein said tracks form concentric circles.

Claim 22

A system according to claim 8 wherein said substrate is made of a thermoplastic material.

Claim 23

A system according to claim 8 wherein said deviations have a height of substantially 0.5 microns.

Claim 24

A system according to claim 8 wherein said deviations have non-uniform lengths.

Claim 25

A system according to claim 8 wherein said deviations have non-uniform spacings.

Claim 26

The system according to claim 8, wherein said illumination means comprises a lens and wherein said optical arrangement also comprises said lens.

Claim 29

The method according to claim 25 wherein said step of illuminating said substrate includes the use of a lens and wherein the step of collecting light reflected from said substrate includes the use of said lens.

Claim 30

An arrangement for reading an optically readable light reflective carrier on which data elements are stored as a succession of projections with respect to a smooth reference surface, the succession of projections forming tracks, each projection having substantially the same width, which width does not exceed 2 microns, a length equal to or greater than its width, and a closer contour in the reference surface, said closed contour being diffractive along its entire extent, wherein each of said projections has a respective one of said data elements stored along said entire length of said diffractive contour, successive data elements along a track being separated by clearance spaces, at least as long as the width of a data element, in the reference surface, with the information contained in said stored data elements being indicated by the extent of each of said closed diffractive contours and by the extent of each of said clearance spaces, the tracks being separated from one another by clearance bands in the reference surface, the tracks having a pitch from one track to the next of at least two times the width of a data element, said arrangement comprising: illumination means for projecting a concentrated light spot onto said carrier and said data elements, said light spot substantially occupying the width of a track being read in order to obtain diffraction of light along the entire length of each of said data elements; an optical arrangement for collecting light reflected from said carrier in such a manner that the maximum light energy is received when the projected light spot impinges on the reference surface and the minimum light energy is received when the projected light spot impinges on a data element, the optical arrangement being configured and positioned such that a part of the light diffracted by said data elements is not collected by said optical arrangement; and detection means receiving the collected light for providing a data readout signal.

Claim 31

An arrangement for reading an optically readable light reflective carrier on which data elements are stored as a succession of projections with respect to a smooth reference surface, the succession of projections forming tracks, each projection having substantially the same width, which width does not exceed 2 microns, a length equal to or greater than its width, and a closer contour in the reference surface, said closed contour being diffractive along its entire extent, wherein each of said projections has a respective one of said data elements stored along said entire length of said diffractive contour, successive data elements along a track being separated by clearance spaces, at least as long as the width of a data element, in the reference surface, with the information contained in said stored data elements being indicated by the extent of each of said closed diffractive contours and by the extent of each of said clearance spaces, the tracks being separated from one another by clearance bands in the reference surface, the tracks having a pitch from one track to the next of at least two times the width of a data element, said arrangement comprising: illumination means for projecting a concentrated light spot onto said carrier and said data elements, said light spot substantially occupying the width of a track being read in order to obtain diffraction of light along the entire length of each of said data elements; an optical arrangement for collecting light reflected from said carrier in such a manner that the maximum light energy is received when the projected light spot impinges on the reference surface and the minimum light energy is received when the projected light spot impinges on a data element, the optical arrangement being configured and positioned such that a part of the light diffracted by said data elements is not collected by said optical arrangement; and detection means receiving the collected light for providing a data readout signal.