Estimation of the minimum laser linewidth achievable with a grazing-grating configuration

The influence of beam divergence on second-order grating dispersion terms is found and discussed. It is shown that divergence in the plane normal to the plane of incidence sets the lowest limit of the achievable linewidth. By using a double-grating configuration to achieve both spectral narrowing and tuning, one can obtain a laser line width down to approximately 0.01 A in a discharge-pumped XeF laser.