What does irradiance mean?
Irradiance is the term used to describe the density of laser power per unit area. Basically it is the power of the beam divided by the area that it covers. As the beam extends further from the projector, the cross-sectional area of the beam increases because of the divergence of the beam. The increase in area, causes the irradiance (power density) to decrease. This is why it is safer to view laser beams over a longer distance. The units for irradiance is watts per square meter (wm-²).
