Experiments with a XeCl* excimer laser have shown that not all resonator co
nfigurations with intracavity Fabry-Perot etalons result in proper output-b
eam formation. We present a model for the growth of the coherence length in
the resonator. This model explains the experimental results with various r
esonator configurations. (C) 1999 Optical Society of America [S0740-3224(99
)00807-3].