Near infrared light
Near infrared light is in the range of 700nm-1400nm on the electromagnetic spectrum and has wavelengths that are longer than those of visible light, meaning that humans can’t see it. Infrared photography most commonly uses near infrared light. A common misconception is that near infrared light is used for thermal imaging, but you actually need far infrared light that.
Near infrared light is also used in a technique named photobiomodulation for the treatment of oral ulcers caused by chemotherapy and wound healing. Scientists are also researching a potential use for near infrared light as a treatment for the Herpes virus.