I've started alignment of OFC3. I've decided to do 775 path first. It is aligned to the point where I see first pass light (i.e. passes through M1 and M2 and onto camera). As well as the second pass light interfering with the first pass to create fringes. In the past once I've been at this point, you scan around on the intercavity mirrors until you see the third pass beam, and then turn on some kind of cavity length/frequency scan to see flashes. I haven't found the third pass beam yet. Hopefully should have a third, functioning 775 cavity soon.
One note: In order for the reflected beam incident on the cavity to clear the input mirror I had to move the two input mirrors back about 1.5 inches each. I also rotated the mount for the second input mirror to give additional clearance. The REFL beam clears the input mirror but only by about an inch or less.
I added a f=100mm lens to the TRANS output and moved the camera back. Then realigned without the fourth mirror on, put the fourth mirror back on and a scan on one of the mirrors revealed the third pass beam. It is now touched up enough to see some 1,0 0,1 and 0,0s flashing. At this point I find a PD is better for alignment. Will set that up after journal club.