MARTIN BOND / SCIENCE PHOTO LIBRARY MARTIN BOND / SCIENCE PHOTO LIBRARY
Paper thickness gauge. This device uses a radioactive source to monitor the thickness of paper during manufacture. The source emits beta radiation, which is absorbed by the paper relatively easily. By measuring the proportion of radioactive particles that goes through the paper, it is possible to accurately calculate its thickness. The source of radiation is a radioisotope of promethium, krypton or strontium.
Model release not required. Property release not required.