Material

A laser's effect depends on the material, wavelength and degree of absorption. Depending on the intensity and exposure time of the laser light, the absorbed light increases the surface temperature or causes the material to melt and evaporate.

Wavelength

The wavelength of the laser beam determines its position in the electromagnetic spectrum as well as its color, e.g. ultraviolet (355 nm), green (532 nm), infrared (1064 nm). The wavelength also determines in large part how light is absorbed by the material and also influences the focal diameter, depth of focus, and photon energy. At shorter wavelengths, a smaller focal diameter is possible and the photon energy is higher.

Absorption

The degree of absorption indicates how much laser light is coupled into the work piece, how much is reflected and transmitted, i.e. how strong the effect of the laser light actually is. The degree of absorption is also affected by the incident angle of the laser beam, the temperature, the physical condition, and the surface quality of the workpiece. For metals, in most cases, a smaller wavelength means a larger absorption number.