In memory of David Fried (1933–2022)

Optics has suffered a severe, irreplaceable loss. Professor David Larry Fried, one of the greatest optical scientists of modern times, has died at age 89.
Fried was born into a Jewish immigrant family in Brooklyn, New York, in 1933. He was educated at Rutgers University, where he earned a bachelor’s degree, master’s degree, and doctorate in physics.
David Fried laid the foundations of modern atmospheric optics and astronomical adaptive optics. He had the ability to describe the complex interactions between optical waves and atmospheric turbulence in simple mathematical language. In his work as a theoretical physicist, Fried relied on the fundamental work performed by various Russian scientists: Mathematician A. N. Kolmogorov and physicists A. M. Obukhov, S. M. Rytov, and V. I. Tatarski˘ı. He became one of only a few scientists whose names have been immortalized in terminological form. He introduced an important atmospheric turbulence parameter—the Fried radius—which has become a fundamental quantity for assessment of the interaction between optical waves and turbulence.
In the early 1980s, Fried studied the possible use of laser backscattering in the atmosphere to control adaptive optics systems; this idea served as a basis for the laser guide star concept. Fried actively participated in experiments demonstrating the practical validity of the laser guide star concept. In 1993, the SPIE international optical society awarded Fried its Technology Achievement Award for this work.
Over his long and fortunate scientific career, Fried made extensive contributions to the description of “strong” intensity fluctuations and the effect of speckle formation on long-distance propagation of coherent optical waves in the atmosphere and was the first to study the details of optical image formation in a turbulent atmosphere for “long” and “short” exposure times. He also worked on suppression of infrared background noise in systems for detecting moving targets, low-temperature optical and far-infrared sensors, and many other areas.
David Fried did not publish much, but, in the 1970s and 1980s, he was the most highly cited scientist in the field of wave propagation, and his work continues to be highly cited and relevant.
David Fried supported consistent scientific engagement with Russian scientists, having worked on scientific conferences and scientific schools involving Russian scientists, and he enthusiastically and amicably reviewed papers published in Russian journals, traveled to Russia to give lectures, and supported nominations of Russian scientists to the governing bodies of international scientific associations.
David Fried will be warmly remembered by those who knew him personally or learned from his work.

Editorial Board
Opticheski˘ı Zhurnal