I updated the beam mode model prevously generated in alogs 30126-30130 (20160930) and alog 39706 (20171208).
It includes arm optics changes, as well as and output path model based on alog 84089 (20250425). With Kevin's help, I checked it aganst the default FInesse model. The models are reasonably close, although this mo9del does not include a) astigmatism, and b) thick otpics.
The model is available here:

/ligo/home/controls/sballmer/20250603/beamCalc.m

Some conclusions:

- In the cold state the SRC eigenmode has a beam size on the ITM of about 6.3cm (the arm mode is 5.3cm).
- To get to the matched "HOT" state, the ITMs need a 25uD lens.
- To match a thermal lens twice as big (50uD), the SR2-SR3 distance would have to shrink 8mm. None of tf the existing mode actuators can get us there.
- I haven't looked whether the PRC needs a simlar fix. I also didn't check whether out sidebands could accomodate this shift with a simple single-optic move.
 

https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=39706

https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=30126

https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=84089