What does irradiance refer to?

Irradiance specifically refers to the power density striking a surface, which is measured in watts per square meter (W/m²). This quantifies the amount of power that is incident on a given area of a surface from a light source, including lasers.

Understanding irradiance is crucial in laser safety, as it helps assess the potential hazards of laser exposure. High irradiance can lead to increased risk of damage to biological tissues or materials, making it essential for Laser Safety Officers to monitor and evaluate irradiance levels in environments where lasers are used.

While energy density, energy received by a medium, and power emitted by a laser are important concepts, they do not accurately capture the definition of irradiance as it is specifically concerned with the density of power delivered to a surface.