초록 ▼

Focus accuracy of a radiant energy recording beam is determined by recording test signals along a spiral track to form on the recording medium a series of adjacent bands. Each band comprises a plurality of track convolutions. Track convolutions in each band are recorded at a focus setting on the rec

Focus accuracy of a radiant energy recording beam is determined by recording test signals along a spiral track to form on the recording medium a series of adjacent bands. Each band comprises a plurality of track convolutions. Track convolutions in each band are recorded at a focus setting on the recording beam which is different by known increments from the focus setting of the beam when track convolutions in respective bands adjacent thereto are recorded. The best focus conditions are obtained at the focus setting of the recording beam forming the brightest band. By comparing the position of that band relative to the position of the band formed by the recording beam at the focus setting at which information is recorded, an accurate determination of the focus conditions thereat is readily obtained from the known increments of focus settings.

대표청구항 ▼

A radiant energy beam recording method for obtaining a measure of the focus setting of a radiant energy recorder comprising the steps of: providing a recording beam of radiant energy; positioning a radiant energy sensitive record medium relative to said recording beam in a manner causing the record

A radiant energy beam recording method for obtaining a measure of the focus setting of a radiant energy recorder comprising the steps of: providing a recording beam of radiant energy; positioning a radiant energy sensitive record medium relative to said recording beam in a manner causing the record to laterally intersect said recording beam; establishing a focus setting for said recording beam in a manner causing a spot to be formed on the surface of said record; establishing relative motion between the record and the recording beam in a manner effecting exposure to the recording beam of selected regions on a first major area of the record surface defining a series of adjacent test bands, the structure of said bands serving as an optical grating, varying said focus setting such that each of said selected regions in each band is exposed at an axial location of the recording beam which is respectively different from the axial location of the recording beam at which said selected regions in respectively other bands are exposed; and examining the light reflected by the optical gratings of said bands to obtain a measure of the optimum focus setting for said recording beam.