Simon, Pengbo

We move the first lens back to the FI direction with 1 cm, then move the second lens by 0.5 cm to the direction of the input beam.

As can be see from the image, the waist z_position change from 80mm to 70mm, and the radius is smaller than before.

we think by moving the second lens for another 0.5 cm, the waist should exist at the z_position around 60 mm.

Also the waist radius might reduce a little bit.