| abstract |
In optically producing a reproducible recording of video or other signals, the intensity of at least one laser light beam is modulated by the signals to be recorded while such light beam scans a substantially flat surface on a photo-sensitive recording medium which is photo-reacted to a degree varying substantially linearly in correspondence with the intensity of the light impinging thereon over a predetermined range of light intensities, and the intensity of the light beam and the degree of modulation thereof by the signals are selected to maintain the maximum and minimum intensities of the modulated light beam within such predetermined range so as to form simultaneously on the record medium a tracking path portion and a recorded signal portion which is unified with the latter. The photo-sensitive record medium is desirably constituted by a positive photo-resist so that, upon development thereof, the tracking path portion is obtained in the form of a groove having the recorded signal portion defined by irregularities at the bottom of such groove. The positive photo-resist or other photo-sensitive material may be conveniently applied as a layer on a base plate or disc which is rotated while the light beam and disc are moved relative to each other in a radial direction of the disc so that the groove or other tracking path portion forms a spiral. |