Write verification in an optical recording system by sensing mark

Abstract

An optical recording system and method which provide verification of recorded data, while the data is being written onto an optical recording medium, by detecting the rate of change of a reflected write pulse. The system includes an optical source for supplying a intensity-modulated incident write signal, having at least one write pulse, to an optical recording medium. The write signal records a logic level of the data on the medium as a mark having a distinct reflectivity. An optical detector detects a reflection of the incident write signal from the medium to provide a reflected write signal which includes a reflected write pulse corresponding to the incident write pulse. The reflected write pulse has a rate of change resulting from a change in reflectivity of the optical medium as the mark is formed thereon. A mark formation effectiveness signal generator receives the reflected write signal and generates a mark formation effectiveness signal which estimates a normalized rate of change of the reflected pulse, to provide an indication of the quality of mark formation on the medium. Comparison means may be included for comparing the measured mark formation effectiveness signal with a predetermined range of acceptable rates of change in order to verify proper mark formation.