[Daniel, Lee, Torrey]

First filter cavity lock!

No REFL dips were found after alignment from the new mode matching solution. Lee suggested instead use the very sensitive SWIR cameras to check in transmission of M2. We first replaced M2 with a 50/50 beam splitter to roughly align the cavity and see the beam making a round trip. Scanning the piezo mirror (M3) allows us to see higher order modes flashing. We use the mirrors before the cavity to align and maximize the 0,0 mode. We then put the HR mirror back in the M2 position instead of the BS. The reason this wasn't done before is we thought the frosted backs of the mirrors in use might obscure the beam, but this was not the case. You can still see a beam through the frosted back. We used the laser lock box to control the cavity with the piezo mirror and achieve a fairly robust lock.