NDI: Invisible to the naked eye
Airman 1st Class Leonard Avalos, 2nd Maintenance Squadron non-destructive inspection, places a weld under an X-radiation machine on Barksdale Air Force Base, La., June 7, 2013. A piece of film is placed under the weld and the X-ray machine will shoot radiation towards it. The weld will be printed on the film for Airmen to properly inspect the piece. (U.S. Air Force photo/Airman 1st Class Benjamin Gonsier)