The possibility of using an image orthicon tube (IO) for detecting low intensity light pulses where spatial resolution, high sensitivity, and high content of information are concerned is examined. A formulation of the signal-to-noise ratio is given in terms of the number of resolvable image points and the working parameters of the tube. An equivalence criterion between an IO and a set of photomultipliers is also given. An unconventional method of target scansion, employing sine modulation of the vertical scansion signal is described. The experimental device, designed for the use of 7.6-cm tubes, is described. The signal-to-noise ratio has been determined by varying the working parameters of the tube and the illumination conditions.