OPTICAL INFORMATION CARRIER,OPTICAL DEVICE FOR GENERATING TRACKING SIGNALS AND OPTICAL DEVICE FOR GENERATING ERROR SIGNALS FOR FOCUSSING

摘要

The process according to the present invention makes it possible for the generation of elements of the discrete preetching or flags the signals focusing error (e) and or of error in the radial following (e). The tags comprise sections shifted 710 - d with respect to the axis means 70 of the tracks 7 has to follow. According to a first variant, each tag comprises sections shifted on either side of the axis. According to a second variant, the tags comprise sections alternately shifted of a size 710 - d, and then the other. In response to the passages of these sections of windows are generated and the pulses granted on by the photodetectors d, d of the interaction of these sections 710 - d on a beam scan focuses f are compares a • • at the other. / p & & p & application in particular for the recording of data], on an optical disk.