Method for laser recording utilizing dynamic preheating
AssigneeThe United States of America as represented by the Director, National Security Agency
InventorMark W. Goldberg
Life of this patent
Estimating the term…
Abstract
An improved method and apparatus for laser recording of information onto a metal film by dynamically heating the film immediately prior to recording. A single track of information is recorded by directing two laser beams onto the film. An unmodulated preheat beam supplies energy to raise the temperature of the metal film to just below that required for recording. A modulated write beam then provides sufficient additional energy to selectively raise the temperature of the film to a necessary level for recording of data.
Claims4
A method of optical recording, comprising:
- focusing an unmodulated beam onto a spot on a thermally sensitive recording medium to heat the medium at said spot to a temperature below the hole formation threshold of the medium;
- cofocusing a modulated beam superimposed onto the unmodulated beam to form a spot the diameter of which is larger than the spot formed by said unmodulated beam, and
- selectively varying the temperature of the medium a said smaller spot above and below the hole formation threshold of the medium.
A method of optical recording, comprising:
- focusing each of a plurality of unmodulated beams onto a separate spot on a thermally sensitive recording medium to heat the medium at each spot to a temperature below the hole formation threshold of the medium;
- cofocusing a plurality of modulated beams, one modulated beam superimposed onto each unmodulated beam to form a plurality of second spots the diameters of which are larger than the spots formed by said unmodulated beams, and
- selectively varying the temperature of the medium at said smaller spots above and below the hole formation threshold of the medium.
Dependencies are inferred from the claim text.