Abstract
Summary: A selenium photovoltaic cell coupled to a mercury electrolytic coulometer makes a useful integrating photometer with the following features: linear response to a wide range of intensities; high sensitivity from 400 to 650 nm; cosine light collection; no power requirements, minimum circuitry; robust, resistant to all environmental conditions; small size, easy construction and low cost. Results from use underwater show good correlation with expected light attenuation and readings can easily be converted to absolute light energy units.