A 40 year old male patient came for routine dental checkup. Patient gives history of root canal treatment with 17 and 27 done using excimer. This type of lasers are:: (A) Special infrared lasers​, (B) Special ultraviolet lasers​, (C) Special visible light lasers, (D) Special blue light lasers​  ​
Answer is B. The lasers range from long wavelengths (infrared), through visible wavelengths, to short wavelengths​ (ultraviolet). Excimers are special ultraviolet lasers.​