Comment to: Why do we see non-zero common, PRC and SRC length signals at the Michelson’s output port?

In the log post there was uncertainty about where some unexpected common-mode arm motion coupling into the anti-symmetric output was coming from. We’ll focus on the last simulation repeated here: Although it looks like the the model is symmetric there is still an additional 90 degrees of detuning on both ITMX and ETMX. Why […]

Why do we see non-zero common, PRC and SRC length signals at the Michelson’s output port?

Question The “Degrees of freedom transfer functions” task in notebook 14 involves applying signals to the cavity mirrors or the power recycling or signal recycling mirror to modulate the differential arm, common arm, power recycling and signal recycling cavity lengths, respectively. We look at a photodetector at the output port of the interferometer, which is […]

Difference in transfer functions of modulation of space and modulation of mirrors

Question: In reference to Task 1, for sheet 13, the above plot is in relation to modulating the space of the cavities, i.e., changing the length of both the cavities. The plot below is modulating the position of the mirror. What is the reason for the difference between the two plots? Theoretically, both the processes […]

Generating node graphs from Finesse scripts

There is a somewhat “hidden” feature in Pykat which is capable of showing you an approximate visualisation of your model. It may not be available on all systems, e.g. Windows. This feature is available in two ways: Via notebook In a Jupyter notebook, you can view your interferometer using the following code: In the example […]

Example Post

Lets see if I can figure out how to make a post with the common elements we might want, and include some how-to steps as I discover them: to insert hyperlinks with different displayed text, first write the display text, then highlight it and either hit ctrl/cmd+k or the link icon at the top of […]


Welcome to the IUCAA Finesse workshop 2019 logbook. This site is a place for us all to share our examples, information about how to use Finesse and solve common problems, links to additional material, and to ask questions. Please don’t be afraid of using this site for any of these purposes! We will retroactively moderate […]