Stability limitations in optical frequency standards

The limiting effects to the stability of optical frequency standards has been assessed. The stability of such a standard depends critically on the spectral width of the atomic absorber. The limiting stability is explored in the absence decoherence (interrogation time limited) and in the more realistic case where optical decoherence and radiative decay are present. The role of motional decoherence in an ion trap system is also discussed. (author)