Basic elements of a laser scanning confocal microscope. Laser light is directed to the scan mirrors via a dichroic mirror. The laser is scanned across the specimen by the scan mirrors and the returning emitted fluorescence is descanned by the same mirrors and transmitted by the dichroic mirror. The fluorescence passes through the barrier filter and is focused on to the pinhole (adjustable iris) before reaching the PMTs. Additional dichroic mirrors can be used to separate fluorescence wavelengths.