A method providing diagnostics of operation of an internal combustion engine ignition coil further including at least one electric cable connecting the ignition coil to at least one spark plug installed in a cylinder head of the engine. A projector comprises: an illumination optical system; a light modulation device; a projection optical system; and a base frame for mounting a plurality of optical components disposed on a light path from the optical illumination system to the projection optical system. The electrode separation of the spark gap or the fluid pressure of the dielectric in the vicinity of the spark gap is then varied by control elements such that all of the spark gaps in an array ignite virtually at the same time, so that their discharge current pulses which lead to the emission of the microwave energy start virtually in phase. A sense amplifier compares an input bit line current to a threshold and outputs a logical low when the bit line current goes over the threshold. An interface is disposed between the operating surface and the control software in order to decouple the first from the latter and transfer any action initiable via the operating surface to the control software. The method and apparatus involve using split detectors and cross-talk cancellation algorithms in the multi-element photodetector of the multi-beam optical disks.