I am using a Newport PAC040, (you should be able to find data through lens catalogs), and the major aberration is Petzval. I am thinking to use a negative lens near image plane as field flattener, but do not how to design such a lens. generally, what principle should I follow?

thanks in advance!☆

noboday answer this?
Anybody can give a guildline on how to choose lens?
when I need pick some lens from catalogs, I only know Focus length and Diameter, but there is so many of such lens with same F and D...

easy，just use a single lens， set the 2 faces as variable,then optimize using aberration, set Petzval to high weight.

well, if I design lens, I probablly can set 2 faces as variable and optimize them. however, in real world, you would not find such lens. so my question is: during the system design, how to choose lens from catalogs to minimize aberration?

If you want to use lens catalog,
you can design a lens in software, then compare with existing lens catalog,
try some different distance to get more results.

what puzzles me is that there are so many different lens from different companies but all have same focus length or similar diameter. I am sure they are all different, maybe different glass V# or different curvature...how do I select a suitable lens? do I need look into all these detail spec?

To the field flattener, the glass type is not important at all.

curvature of two surfaces is the key.
You need to find out every lens’’ curvature data and compare them with your design.

Thank you very much, ukyochen!
now I can see it needs lots of work to select good lens during the system design.