Question

A 3 mW red ( = 670 nm) laser pointer produces a 2 mm diameter spot on a screen.

a) If we place a f = 1cm lens before the screen, and the radius of curvature of the wavefront reaching the lens is 2 m, find the waist of the focused light.

b) The intensity of the light at the center of the beam is given by Imax= 2P/πw2(in W/m2). Calculate the maximum intensity at the focal point.

c) If we place a second lens with f2= 10 cm after the first one at a distanced = f1+ f2, by how much will the beam size, the divergence and the zR after the two lenses change in comparison to the beam size, divergence and zR before them

Answer 1