Multiple layer, multiple track optical disk access by confocal interference microscopy using wavenumber domain reflectometry and background amplitude reduction and compensation

Claim 1

A method for discriminating an in-focus image of an information-bearing region within an optical disk from an out-of-focus image so as to reduce errors in reading information represented by the information-bearing region within the optical disk, comprising the steps of: (a) producing a probe beam and a reference beam from a monochromatic point source; (b) producing antisymmetric spatial properties in the reference beam; (c) producing an in-focus return probe beam by directing the probe beam to an in-focus image point within the information-bearing region; (d) producing antisymmetric spatial properties in the in-focus return probe beam; (e) interfering the reference beam with a beam from an out-of-focus image point; (f) interfering the reference beam with the in-focus return probe beam; (g) reducing systematic and statistical errors in data produced by the detector to represent the information being read by detecting i. the reference beam as a nonlinear function of an amplitude of the reference beam, and ii. the in-focus return probe beam as an interference term between a reference beam and the in-focus return probe beam by means of a detector, an amplitude of an interference term between an amplitude of the out-of-focus image beam and an amplitude of the reference beam being substantially reduced.

Claim 2

A method for discriminating an in-focus image of an information-bearing region within an optical disk from an out-of-focus image so as to reduce errors in reading information represented by the information-bearing region within the optical disk, comprising the steps of: (a) producing a probe beam and a reference beam from a monochromatic point source; (b) producing antisymmetric spatial properties in the reference beam; (c) producing an in-focus return probe beam by directing the probe beam to an in-focus image point within the information-bearing region; (d) producing antisymmetric spatial properties in the in-focus return probe beam; (e) interfering the reference beam with a beam from an out-of-focus image point; (f) interfering the reference beam with the in-focus return probe beam; (g) reducing systematic and statistical errors in data produced by the detector to represent the information being read by detecting i. the reference beam as a nonlinear function of an amplitude of the reference beam, and ii. the in-focus return probe beam as an interference term between a reference beam and the in-focus return probe beam by means of a detector, an amplitude of an interference term between an amplitude of the out-of-focus image beam and an amplitude of the reference beam being substantially reduced.

Claim 3

A method for discriminating an in-focus image of an information-bearing region within an optical disk from an out-of-focus image so as to reduce errors in reading information represented by the information-bearing region within the optical disk, comprising the steps of: (a) producing a probe beam and a reference beam from a wideband point source; (b) producing antisymmetric spatial properties in the reference beam; (c) passing the probe beam through a dispersal element to convert the probe beam to a beam focused to a line in the information-bearing region; (d) producing an in-focus return probe beam; (e) producing antisymmetric spatial properties in the in-focus return probe beam; (f) spatially filtering the in-focus return probe beam; (g) passing the spatially filtered in-focus return probe beam through a dispersal element to convert it to a beam focused to a line in a detector plane of a detector; (h) spatially filtering the reference beam; (i) passing the spatially filtered reference beam through a dispersal element to convert it to a beam focused to the line in the detector plane; (j) spatially filtering a beam from an out-of-focus image point; (k) passing the spatially filtered beam from the out-of-focus image point through a dispersal element; (l) interfering the spatially filtered reference beam with the spatially filtered beam from the out-of-focus image point; (m) interfering the spatially filtered reference beam with the spatially filtered in-focus return probe beam; and (n) detecting (1) the spatially filtered reference beam as a nonlinear function of an amplitude of the spatially filtered reference beam and (2) the spatially filtered in-focus return probe beam as an interference term between the spatially filtered reference beam and the spatially filtered in-focus return probe beam by means of the detector, an amplitude of an interference term between an amplitude of the spatially filtered out-of-focus image beam and an amplitude of the spatially filtered reference beam being substantially reduced, to reduce errors in data produced by the detector to represent the information being read.

Claim 4

A method for discriminating an in-focus image of an information-bearing region within an optical disk from an out-of-focus image so as to reduce errors in reading information represented by the information-bearing region within the optical disk, comprising the steps of: (a) producing a probe beam and a reference beam from a wideband point source; (b) producing antisymmetric spatial properties in the reference beam; (c) passing the probe beam through a dispersal element to convert the probe beam to a beam focused to a line in the information-bearing region; (d) producing an in-focus return probe beam; (e) producing antisymmetric spatial properties in the in-focus return probe beam; (f) spatially filtering the in-focus return probe beam; (g) passing the spatially filtered in-focus return probe beam through a dispersal element to convert it to a beam focused to a line in a detector plane of a detector; (h) spatially filtering the reference beam; (i) passing the spatially filtered reference beam through a dispersal element to convert it to a beam focused to the line in the detector plane; (j) spatially filtering a beam from an out-of-focus image point; (k) passing the spatially filtered beam from the out-of-focus image point through a dispersal element; (l) interfering the spatially filtered reference beam with the spatially filtered beam from the out-of-focus image point; (m) interfering the spatially filtered reference beam with the spatially filtered in-focus return probe beam; and (n) detecting (1) the spatially filtered reference beam as a nonlinear function of an amplitude of the spatially filtered reference beam and (2) the spatially filtered in-focus return probe beam as an interference term between the spatially filtered reference beam and the spatially filtered in-focus return probe beam by means of the detector, an amplitude of an interference term between an amplitude of the spatially filtered out-of-focus image beam and an amplitude of the spatially filtered reference beam being substantially reduced, to reduce errors in data produced by the detector to represent the information being read.

Claim 8

A method for discriminating an in-focus image of an information-bearing region within an optical memory medium from an out-of-focus image so as to reduce errors in reading information represented by the information-bearing region within the optical memory medium, comprising the steps of: (a) producing a probe beam and a reference beam from a wideband point source; (b) producing antisymmetric spatial properties in the reference beam; (c) converting the probe beam to a beam focused to a line in the information-bearing region; (d) producing an in-focus return probe beam; (e) producing antisymmetric spatial properties in the in-focus return probe beam; (f) spatially filtering the in-focus return probe beam; (g) passing the spatially filtered in-focus return probe beam through a dispersal element to convert it to a beam focused to a line in a detector plane of a detector; (h) spatially filtering the reference beam; (i) passing the spatially filtered reference beam through a dispersal element to convert it to a beam focused to the line in the detector plane; (j) spatially filtering a beam from an out-of focus image point; (k) passing the spatially filtered beam from the out-of-focus image point through a dispersal element; (l) interfering the spatially filtered reference beam with the spatially filtered beam from the out-of-focus image point; (m) interfering the spatially filtered reference beam with the spatially filtered in-focus return probe beam; and (n) detecting (1) the spatially filtered reference beam as a nonlinear function of an amplitude of the spatially filtered reference beam, and (2) the spatially filtered in-focus return probe beam as an interference term between the spatially filtered reference beam and the spatially filtered in-focus return probe beam by means of the detector, an amplitude of an interference term between an amplitude of the spatially filtered out-of-focus image beam and an amplitude of the spatially filtered reference beam being substantially reduced, to reduce errors in data produced by the detector to represent the information being read.

Claim 9

A method for discriminating an in-focus image of an information-bearing region within an optical memory medium from an out-of-focus image so as to reduce errors in reading information represented by the information-bearing region within the optical memory medium, comprising the steps of: (a) producing a probe beam and a reference beam from a wideband point source; (b) producing antisymmetric spatial properties in the reference beam; (c) converting the probe beam to a beam focused to a line in the information-bearing region; (d) producing an in-focus return probe beam; (e) producing antisymmetric spatial properties in the in-focus return probe beam; (f) spatially filtering the in-focus return probe beam; (g) passing the spatially filtered in-focus return probe beam through a dispersal element to convert it to a beam focused to a line in a detector plane of a detector; (h) spatially filtering the reference beam; (i) passing the spatially filtered reference beam through a dispersal element to convert it to a beam focused to the line in the detector plane; (j) spatially filtering a beam from an out-of focus image point; (k) passing the spatially filtered beam from the out-of-focus image point through a dispersal element; (l) interfering the spatially filtered reference beam with the spatially filtered beam from the out-of-focus image point; (m) interfering the spatially filtered reference beam with the spatially filtered in-focus return probe beam; and (n) detecting (1) the spatially filtered reference beam as a nonlinear function of an amplitude of the spatially filtered reference beam, and (2) the spatially filtered in-focus return probe beam as an interference term between the spatially filtered reference beam and the spatially filtered in-focus return probe beam by means of the detector, an amplitude of an interference term between an amplitude of the spatially filtered out-of-focus image beam and an amplitude of the spatially filtered reference beam being substantially reduced, to reduce errors in data produced by the detector to represent the information being read.