Abstract

With a working drive it is difficult to dynamically measure the beam profile formed on the optical disk because of the rotation of the disk and the movement of optical head due to auto focusing. We have developed the measurement method of the beam profile on a rotating optical disk, which is based on the scanning knife edge method[1]. To apply this method to an actual drive, we proposed two techniques. The first one is to detect the transmission light through the measurement disk with an external PIN photodetector, and the second is to detect the reflection light by using the built-in photodetector of the drive(Fig.1)[2]. The merits and demerits of both measurement techniques are clarified by comparing each other. We present the Influence of the distance between the detector and the disk.

© 1998 IEEE