Confocal laser scanning microscope. Confocal microscopy uses fluorescent dyes to highlight tissues, cellular structures and proteins in the samples being analysed. A laser beam (red) is passed through a lens that focuses it on to a beam splitter. Some of the laser beams are directed to the sample. The fluorescent dyes in the sample are excited by the laser beams and emit fluorescent light. This light passes back through the beam splitter and is collected by a digital camera. Photographed at the National Physical Laboratory, Teddington, UK.