Abstract: A radiation detector that combines the characteristics of high quantum efficiency in the UV spectrum with good IR transmission characteristics so that it may be used in association with an IR sensor to produce a coaxial transducer suitable for use in association with unfiltered, high-resolution optics. The detector is a solid state photovoltaic Schottky barrier semi-conductor junction comprising a thin platinum layer laid over single-crystal cadmium sulfide. Processing, including lapping, polishing, and chemical etch, produces a surface suitable for providing radiation sensitivity which drops off sharply outside of the ultraviolet spectrum beyond 550 nanometers. The platinum layer is approximately 35 angstroms in thickness and is therefore transparent both to ultraviolet and infrared radiation. The infrared radiation passes through the cadmium sulfide wafer and through a window in the indium ohmic contact surface on the second surface of the cadmium sulfide crystal.