Recording informatioin on an optical disc without using pre-manufactured

Abstract

An apparatus for controlling the spacing between information tracks while recording information on an optical disc that does not have pre-manufactured information tracks. The invention employs a precision reference scale to guide the position of information tracks recorded on an optical disc. The reference scale is a linear strip with spaced optical tick marks. The spacing of the optical tick marks on the reference scale directly correlates to track pitch between information tracks recorded on the optical disc. The invention utilizes a first optical system for reading-from and writing-to an optical disc. A second optical system is used for detecting optical tick marks on the reference scale. The first optical system and the second optical system share common optical components. Optical components in common to both the first and second optical systems include a light source, a diffraction grating, a field lens, and a beam splitter. Components unique to each optical system includes an objective lens and a field lens for the first optical system and a beam splitter, objective lens and field lens for the second optical system. The first optical system operates in direct correlation with the second optical system during the recording process.