Light shifts in an optically pumped Cs beam frequency standard

Frequency shifts caused by light, which are called light shifts in an optically pumped Cs beam frequency standard, were estimated. Frequency shifts due to monolithic light were measured by introducing laser light along the Cs beam. The relative dependence of the shift on the laser frequency agreed very well with the theory, but the absolute shift was between one and two times that of the theory. The light shifts due to the optical pumping and optical detection in the standard are estimated to be less than 2×10^-15 and 1×10^-16, respectively, and both are negligible at the present state of development