The inverse square law is a principle that applies to the intensity or power of radiation, including laser beams. According to the inverse square law, the intensity of a laser beam decreases as the square of the distance from the source increases. Mathematically, the inverse square law is expressed as:
I = P / (4πr²),
where:
- I is the intensity of the laser beam,
- P is the power or radiant flux of the laser,
- r is the distance from the laser source.
In this equation, the intensity (I) is inversely proportional to the square of the distance (r) from the source. This means that as the distance doubles, the intensity decreases by a factor of four, and as the distance triples, the intensity decreases by a factor of nine, and so on.