Method for preventing interchange of optical information carriers

The invention relates to a method for preventing interchange of a first optical information carrier with a second optical information carrier in an optical drive. Initially, the light is focused at the first optical information carrier in the optical apparatus followed by the steps of detecting reflected light from the first optical information carrier and generating a plurality of signals (CA, RF, FE) from the detected light, such as a focus error signal (FE). Upon obtaining an indication of a signal, e.g. the focus error signal (FE), is absent or reduced below a certain level, there is a step of assessing if the first optical information carrier has been removed from the optical drive. If removed, reproduction of information by the optical drive is made impossible until some pre-determined measures have been taken, e.g. restart of the optical drive or other measures.