Veylith / aberration bench
See where the phase
leaves the axis.
A transparent OPD record and a finite-grid third-order Seidel fit for the real spherical prescription. Fast singlet is the teaching specimen; every number below carries its wavelength, stop, field, reference, and validity limits.
Source prescription
Choose the system under inspection
Tracing the pupil and field grid
Computing index-weighted path lengths, subtracting each field chief ray, and checking the third-order fit before displaying any coefficient.