Hi,
Question as described in the title. The spot size i mean here is neither RMS or GEO spot size, it is the calculation size like Airy Radius with diffraction effect consideration. Airy spot size is the min spot size in focusing distance, but how does OpticStudio calcuate the spot size in de-focus distance? what is (are) the formula(s)? Similarly for MTF calculation, just using a paraxial lens with known EFL and imaging F/#.
Thanks,
Roger