In a method and circuit for retracting a data transducer carrying assembly in a mass data storage device, has the assembly is positioned in response to a voltage applied to a driver mechanism, and a crash-stop barrier against which the assembly contacts when the assembly is moved to the retract position. An optical block includes refraction surfaces to narrow the distance between two or more light transmission paths through the optical block thereby enabling a module to be coupled to closely spaced fiber optic connectors. Furthermore, the invention discloses a process and device for determining an externally generated variable that drives or brakes the vehicle as well as for supporting uphill starting. When the light-stimulated writing is carried out with light from a light source according to image information, an efficiency of light-heat conversion can be enhanced by a light -absorbing element.