Confocal microscopes work to block out of focus light by utilising the pinhole and therefore generate clearer images than those from a widefield system. Confocals are either laser scanning confocal microscope (LSCM) configurations utilising a detector and point scanning system, or spinning disk microscope which uses a array of pinholes configured on a disk which spins.

Spinning disk confocal laser microscopy (SDCLM) overcomes this problem by exploiting the multiplex principle where the sample is illuminated and light detected at multiple points simultaneously. Unlike a conventional laser-scanning confocal microscope with a single pinhole, where a narrow laser beam sequentially scans the sample, in SDCLM an expanded beam illuminates a spinning disk array of microlenses and pinholes which produce multiple focused laser beams which scan across the specimen