Participaint: Marc, Matteo and Yuhang

Since we have finished the lens installation for OPO, we arrived the alignment of OPO.

Last week, me and Marc did a similar work, including the preparation of periscope, camera, iris, OD filter and the alignment of the beam(make it hight of 140mm). However, the elevation of beam costs too much space. It makes the beam waist locate just after the periscope. After that we decide to alignment the OPO without the translation/tilt stage. However, the work seems impossible without that stage.

Yesterday, we changed the set of stage(make it hight of 111mm). This saves us a lot of space. We also did the beam measurement and find the beam is desirable.(as in the attached figure) We set up the periscope and did the pre-aligment of OPO. The pre-alignment is to make the reflection of OPO roughly overlap with incident beam. The fine-alignment will be done today by using translation/tilt stage. For the components after OPO, we set up a dichroic mirror instead of OD filter to damp the beam and also get the reflection information. For the transmission of dichroic, we use a camera to monitor. We also align it before putting OPO. And made a circle to mark it on the screen.(as in the attached figure). We also set up a photo diode for the reflection of dichroic mirror.

The video of check the reflection is here. https://drive.google.com/file/d/1-ZfhVS0iZDxF7kWpSCrn2QO5ORTTX4xU/view?usp=sharing

The whole set up is attached as well.