It would be great if you could find a cite for the dielectric mirror observation and comment in the StackExchange thread—thanks!
Googling dielectric mirror phase shows up several citations for a pi phase shift (though I think those were all 100% reflectance mirrors). A good citation for a pi/2 phase shift seems to be here, though I haven’t actually double-checked it.
It would be great if you could find a cite for the dielectric mirror observation and comment in the StackExchange thread—thanks!
Googling dielectric mirror phase shows up several citations for a pi phase shift (though I think those were all 100% reflectance mirrors). A good citation for a pi/2 phase shift seems to be here, though I haven’t actually double-checked it.