Laser surgery: the variety of effects of lasers on living tissues has provided alternatives to the scalpel and stitch in some surgical operations. A laser produces an intense beam of light of a specific wavelength, which depends on the type of laser; carbon dioxide, argon and Neodymium yttrium-alumimium-garnet are examples of medical lasers used in different applications. A low- energy laser beam might be used to coagulate bleeding around an ulcer, yet at high power be focussed to operate as a fine scalpel. Different lasers are used for removal of skin blemishes (tattoos & port wine stains), for retinal surgery and for early treatment of cervical cancers.