Substrate absorption is not consistently accounted for
There are two parameters found in IFO models that refer to substrate absorption:
ifo.Optics.ITM.SubstrateAbsorption. It's not well documented which one is supposed to be used for what.
A quick grep suggests that
ifo.Optics.ITM.SubstrateAbsorption is not currently used anywhere in the code, except for the obsolete
ifo.Optics.SubstrateAbsorption is used only for a BS thermal lensing power limit check in
We should track total absorption in all substrates that are inside the PRC/SRC (ITMs and BS), in order to correctly estimate the power recycling gain and SRC loss. We should track absorption in each substrate for thermal lensing limits, and for heat budgeting purposes in cryo substrates.