John E. Greivenkamp Created 2026-10-13 Updated 2026-11-05
An optical scientist whose work included interferometry, optical testing and ophthalmic instrumentation.[ref] His teaching in radiometry carefully distinguishes radiance from total transmitted power. Across a refracting interface, the invariant quantity in an ideal system is radiance divided by the square of refractive index; accounting for this prevents brightness calculations from confusing a change in the angular spread of rays with a gain of optical power.[ref]