... glass, double-alkali photocathode Diameter of 28.5mm(1.12 inch), nine stage, side-on photomultiplier tubes ... , double-alkali photocathode Features: Diameter of 28.5mm(1.12 inch), nine stage, side-on photomultiplier tubes, ... dust meter, light meter, radiation calorimeter,scanning electron microscopy, turbidity meter, particle counter, biochemical analyzer, X-ray camera timer, optical density meter, ...