Recent content by Nanxie

looked up the 'q parameter' and you're right~ Just need the Matrix ABCD to calculate the beam parameters at any z. thank you! ^^

Homework Statement Hello, I'm really confused about this one, =( Suppose I have a guassian beam that is colliminated (beam expanded) and then suppose i let it passed through a lens to focus it. Given an initial waist and focal length of the lens. How can i find the waist (or half width)...