Infrared radiation harmful effects: Prolonged exposure to IR radiation causes a gradual but irreversible opacity of the lens. Other forms of damage to the eye from IR exposure include scotoma, which is a loss of vision due to the damage to the retina. Even low-level IR absorption can cause symptoms such as redness of the eye, swelling, or hemorrhaging

Roentgen named his discovery X-strahlen—strahlen being German for “beam” or “ray,” and “x” being used in mathematics to indicate an unknown quantity.  Even though we now know much more about how x-rays work, their name has retained a sense of their original mystery. The rays have also been called “Roentgen's rays,” and the images they produce are sometimes known as “roentgenograms.”