Focus control manner and information record media origin board creation manner and focus control unit and information record media origin board creation device

摘要

PROBLEM TO BE SOLVED: To easily detect the deviation of a distance between an objective lens and a recording medium from a desired distance by accompanying a change in the state of recording light during recording.;SOLUTION: The focus control to maintain the distance between the objective lens 206 and the recording medium 207 at a constant distance is executed by using light having good detection sensitivity at a wavelength longer than the wavelength of the recording light. The out-of-focus of the recording light is detected from the reflected light of the recording light reflected by the recording medium 207 and the control objective position of the focus control circuit is corrected, by which the distance between the objective lens 206 and the recording medium 207 is corrected to the desired distance throughout the recording. As a result, the recording light of a UV region which is low in the detection sensitivity is subjected to the good focus control and the focus control position of the recording light is corrected throughout the recording. At this time, the focus control is so executed that the focus of the recording light exists nearly at the center in the thickness direction of the photosensitive material film on the recording medium 207, by which micropits are formed with good accuracy.;COPYRIGHT: (C)2001,JPO