Participants: Yuhang, Eleonora, Matteo

The transmission found before seems to come from a beam passing through a gap beside the crystal (it was too bright and the reflection was very small and with a strange shape)

 Therefore we have restarted the alignment from the beginning.  We moved the the 9071 newport Four-Axis Tilt Aligner under the OPO following the usual procedure:

1. Make the reflection superpose the incoming beam

2. Look for a good transmission, always taking care to keep the reflection superposed to the incoming beam.

After may tries we could find a resonably good shaped transmitted beam with a power of  0.047mW. The input power was 210mW. This means the reflectivity is 99.977%, which is in agreement with what we expect.

We put a dichroic mirror after the OPO. The reflection is focused on a photodiode while the trasmission is sent to a camera. Before installing the OPO we have marked the position of the transmitted beam on the screen in order to use it as a reference for the alignment.

Unfortunaltely  the tramission after the dichroic mirror is too low and we cannot see any light on the camera, therefore we were not able to use the reference we took for the transmitted beam.