Ja. Ruff et Ae. Siegman, MEASUREMENT OF BEAM QUALITY DEGRADATION DUE TO SPHERICAL-ABERRATION IN A SIMPLE LENS, Optical and quantum electronics, 26(6), 1994, pp. 629-632
We have measured the effect on laser beam quality factor M2 of spheric
al aberration in a simple planoconvex lens. Theory predicts that the l
aser beam quality should remain essentially unchanged until the incide
nt beam width w exceeds a critical width w(q) above which the beam qua
lity will degrade rapidly, with the M2 value increasing as (w/w(q))4.
We find good agreement between this theory and our experimental data.