Laser laser devices. The question of just how to assign credit for inventing the laser remains unresolved by historians. On May 16, 1960, Theodore H. Maiman operated the first functioning laser at Hughes Research Laboratories, Malibu, California, ahead of several research teams, including those of Townes, at Columbia University, Arthur Schawlow, at Bell Labs, and Gould, at the TRG (Technical Research Group) company. Maiman's functional laser used a solid-state flashlamp-pumped synthetic ruby crystal to produce red laser light, at 694 nanometers wavelength; however, the device only was capable of pulsed operation, because of its three-level pumping design scheme. Later that year,
Laser coagulation radiation proctitis can occur, which involved chronic bleeding in the colon. Treatment with s and with Nd:YAG laser passed through a Potassium titanyl phosphate crystal, and with an argon laser has been studied in small clinical trials. Nd:YAG laser has been abandoned due to risks of damaging the colon wall, fibrosis, stricture formation, and recto-vaginal fistula, and severe damage in case of accidents, as well as the cost. The other two modalities were largely replaced by argon plasma coagulation by 2011, which was safer and less expensive. In the eye, side effects and complications of laser photocoagulation are not infrequent