Optical recording medium and method for improved pit geometry and

Abstract

The invention discloses a method and an apparatus for creating optical disc recordings by forming pits having ideal shapes. These ideally shaped pits are improvements in the technology of disc mastering, due to the manufacturing and data playback advantages that are inherent in the ideally shaped pits. A disc substrate has a very thin partially reflective layer applied to the surface of the optical disc upon which data will be recorded. The substance used to make the partially reflective layer is normally considered opaque in more commonly occurring thicknesses. However, the partially reflective layer, is created to be so extremely thin that it becomes partially optically transparent. The partially reflective layer then has spin coated, thereon, an optically active lamina to enable the recording of data on the disc by laser means in the form of pits. The pits are created by having a laser light focusing on both the partially reflective layer and the optically active lamina, both which react to the irradiation causing a pit to be formed. The resulting pit is without a raised berm area surrounding the pit, in what is considered to be an ideal shape for a pit. An OD master can be created by finally depositing a conductive and reflective lamina over the pitted active lamina. The invention is also useful in providing increased laser tracking. Here, the partially reflective layer provides increased signal to noise ratio, enhancing laser tracking in both the recording and playback modes.