Yuhang and Michael

We took some equipment from TAMA - camera + TV setup for when we will assemble the OPO cavity there, as well as some mounts to keep the beam height correct (should be 76mm).

The Faraday Isolator was placed and characterised. There was a scratch on the polariser window which reduced transmission somewhat, so the fine tuning of the translation stage on the FI mount was adjusted to avoid this.

The power of the Lightwave laser placed there does not seem very stable and drifts from minute to minute.

If the Faraday isolator is not well aligned along the beam axis, the beam becomes astigmatic.

Using the Thorlabs power meter, we measure the following:

• Initial transmission adjustment: 4.79 mW transmit, 5.03 mW incident
• Blocking adjustment: 0.25 µW transmit, 5.185 mW incident
• Placed back in transmitting mode: 4.991 mW transmit, 5.343 mW incident

This gives us 93.4% power transmission and 43.2 dB isolation (Thorlabs specifies 92% transmission and 35 dB isolation).