DEVICE AND METHOD FOR MAINTAINING OPTICAL ENERGY DENSITY ON A STORAGE MEDIUM

摘要

A system and method are provided for maintaining optical energy density on a marking area of a storage medium. The method includes the operation of directing a light beam from a light source to an optical system (410). The light beam can pass through at least one optical component in the optical system, where the optical system has astigmatic properties selected so as to maintain an irradiance within a defined area on the marking area of the storage medium through a range of working distances between the optical system and the marking surface (420). A further operation is guiding the light beam by the optical system onto the marking area of the storage medium (430).