Confocal microscopy requires intense, near-monochromatic illumination which is provided by a laser.

Some lasers can be dangerous, and so they are categorized by their wavelength and power, with Class I being the least powerful and Class IV being the most penetrating.

The lasers used in confocal microscopes are Class IIIB, which means they may be hazardous if your eye is exposed directly, but reflections from the laser on matte surfaces are not harmful.