David W. Koopman, 44, a professor of physics at the University of Maryland since 1964, died of cancer Friday at Montgomery General Hospital in Olney.

Dr. Koopman was born in Caro, Mich., and grew up there and in Philadelphia. He graduated from Amherst College in Amherst, Mass., and earned a doctorate in physics at the University of Michigan at Ann Arbor in 1964.

He joined the faculty at Maryland in that year. His specialities were optics and the use of lasers to produce and study hot ionized gases -- known as plasmas -- which may become a source of useable energy in the future. In addition to his work at Maryland, where he taught at the Institute for Physcal Science and Technology, he was a consultant at the Naval Research Laboratory and with Various private concerns in the Washington area.

Dr. Koopman, who lived in Brookeville, Md., contracted cancer two years ago. He was cared for throughout his illness by Linda Guerkink.

His marriage to the former Elizabeth Jansen ended in divorce.

Survivors include two children, Philip and Stephen, of Bethesda; his parents, Mr. and Mrs. Philip U. Koopman, of Philadelphia; a brother, John P. Koopman, of Newtown, Pa., and two sisters, Maryann McFarlin, of Staunton, Va., and Kathryn Byrd, of Manassas, Va.