Photocounts and laser detection of weak optical signals

The nature of photocounts arising in detectors exposed to highly coherent laser ra discussed. It is shown that the spatial localization of a photon allowed in quantum electrc fails to account for the effect observed and that the Coulomb instability of a low elector photodetector can be the explanation. With detectors utilizing non-free electrons, namely, bound in atoms, ions, molecules, etc., weak optical signals can be detected with laser without photocounts, in other words, at a suppressed shot noise. A basic scheme fc detector using bound electrons is suggested.