Wavelength and absorption

The amount of laser energy that a material absorbs depends on the wavelength. For example, glass is almost impossible to process in the visible range; but this is more successful with UV lasers (< 400 nm) and long-wave infrared light (< 5 µm) since the absorption increases considerably here. Vice versa, the absorption rate of iron and steel is highest in the visible to near-infrared range. That does not apply to very reflective metals like copper, gold, silver, and aluminum. For example, at the 980 nm wavelength, copper absorbs less than five percent and at 600 nm just a quarter of the occurring light energy. There is no point considering laser processing in this instance. On the other hand, the non-ferrous metal absorbs violet and blue light at rates of between 65 to above 70 percent.