Participaint: Aritomi, Eleonora and Yuhang

According to the optical layout, the lens should be 250mm before beam waist. And the beam waist is 390um. By putting a 30mm lens, we found the beam waist after lens will be 22um. The distance of the waist from the lens is 29mm. The corresponding rayleigh range is 1.4mm. The aperature of homodyne detector is 0.5mm, so we should make the going inside beam smaller than 100um. The range of beam smaller than 100um is 12mm.

The measurement result agrees with the simulation. The result is attached in the figure2.