Today, I wrote up my noise calculations in a nicer way so that I have it on hand in the future. They are attached here. I found a mistake from the last elog entry, so it turns out that we are looking at a linewidth of about 440 kHz (or a PSD noise of 191 Hz/rtHz). This still meets the requirements of the experiment, and can be adjusted as necessary, since I can still increase the length of the cavity to decrease the noise. 

LIGO students had another presentation by Dr. Weinstein about the general progress of the LIGO project this afternoon. There was some discussion of decreasing noise level and aLIGO. 

Just musing: There is some discussion of using a lens to focus the beam (e.g. Saito paper, Saliba paper). I'm not sure how this will affect the noise levels; it might be possible to decrease the noise on the ECDL a lot if we include a lens that focuses the beam? In the Saito paper, they talked about having the beam aligned to focus at 10 m, with a lens of 15 mm focal length. Tara hasn't been around today but I want to talk to him about the idea, because it could affect the noise level. Alternately, multiple mirrors to redirect the beam and make the cavity longer before hitting the grating, although this sounds more complicated.