MetroLaser, Inc., uses the General Electric J85 engine, seen here, at the University of Tennessee Space Institute’s Propulsion Research Facility near Arnold Air Force Base, Tenn., to study its three-component planar Doppler velocimetry, or PDV, measurement system for optical, non-intrusive measurements of exhaust gas velocity Nov. 18, 2021. Through a Small Business Innovative Research contract awarded to MetroLaser, by the U.S. Navy, the PDV system is being developed to measure the gas velocity of engine exhaust to help the Navy in developing strategies to reduce noise from aircraft. (U.S. Air Force photo by Jill Pickett)