Infrared laser beams were used for both hard- and soft tissue surgery. For soft tissue
surgery Carbon Dioxide lasers operating at a wavelength of 10600 nanometer were
commonly used. This type of middle infrared radiation was highly absorbed by
water-containing tissue, which vaporised under the impact of a focussed laser beam.
Incisions could be as small as one- to a few tenths of a millimeter. A defocused beam
could be used to seal the ends of vessels and nerves. Hard tissues like bone and
teeth could be cut with an Er:YAG laser (2940 nm) whose operation was based on
just another absorption peak of water. Surface scars caused by acne and other skin
diseases could successfully be reduced with lasers operating in the near infrared part
of the electromagnetic spectrum, like 1064 and 1320 nanometer Nd:YAG lasers and
1450 nm diode lasers.