You can definitely test R2 directly through R1 by Foucault and follow the expected longitudinal aberration (see pic #2). This surface when tested through the lens behaves like an oblate with eccentricity of approx 0.5. Problem is Bath interferometry - I have no idea how much Bath reference beam gets affected by the lens ... so no idea what DFTF would report as final eccentricity. I can model a narrow laser beam through R1, reflect it from R2 and back though R1 and tell you how much it will get deformed, but I have no idea how those two fronts will
interfere (what pattern the interferogram will look like). Zemax can't do that. Or rather
I can't do that in Zemax
