Determination of the ten second order intensity moments

The general astigmatic beam can be characterized by its ten second order mo ments in first order approach. Most intensity moments, except the beam twis t, can be determined by measuring the intensity in a reasonable number of p ositions around the waist of the beam. The beam twist is determined by appl ying a rotated cylindrical lens. The ten intensity moments of two kinds of astigmatic beam were determined: a simple astigmatic TEM8,0 Hermite-Gaussia n beam and a twisted beam generated from the TEM8,0 mode. The experimental results were compared with the theoretical calculations and demonstrate tha t the ten second order moments of a beam can be determined in a rather simp le way. (C) 1998 Elsevier Science Ltd. All rights reserved.