Figures of merit for laser beam quality

We show how FWHM, FWI/e 2, Strehl ratio, and encircled energy figures of merit vary with different types of aberration and measurement methods. We examine in detail the array sampling method and the slit-scan method. Our irradiance in the exit pupil of the optical system is a simple gaussian. We found that in general the slit-scan method and the array method do not yield the same result. The width measurements for the central lobe of the diffraction pattern are very insensitive to aberration. 2