Manuel, Kuroki

We measured the beam waist of the probe at the detector.
We used a blade and a vertical micrometric stage to move the blade with steps of 0.5mm.

We did this for the 1310nm laser using a power meter for infrared lasers (and repeated the measurement twice).
Kuroki-san made the fit of the data with a gaussian cumulative function  erf(x/c) where x is the blade position and c = w/sqrt(2)

Result: w = 2.57±0.05 mm

For the HeNe laser the power is too low, so the resolution of the power meter was not good, so we used the smaller one. The small one was too small for the size of the beam, so after the blade we put a lens (f=19mm) to focus the beam on the power meter.
Result: w = 2.40±0.05 mm