
Using the LSA fan
The LSA (Longitudinal Spherical Aberration) is a plot of focal distance versus pupil coordinate that allows you to judge the zonal contribution to spherical aberration.
To open the LSA window:
- Select from the menu Analysis > Fans > Longitudinal
The LSA is displayed as a function of the normalized pupil coordinate. A tangential scan is made, using the y radius of the entrance pupil. The options button will summon a utility window that will let you change the number of points at which the LSA is calculated.