New formula for eliminating spherical aberration

[Dali]

Thanks for the comments.

I think that using the paraboloid surface to correct spherical aberration only applies to mirrors, not lenses. For mirrors the correction for spherical is, of course, perfect. Off-axis perfomance is, however, not great, which is the reason that Schmidt optical designs are often used for wide angle telescopes.

View attachment 228750

Isn't Schmidt design including a freeform lens?

 

[darkosaric]

Yes, I would say it is somewhat the same thing.

Engineers often face problems where they need to optimize three parameters, such as fast, good, and inexpensive. Then they say "you can have any two of the three. Which two do you want?"

And nevertheless I often hear from managers that they want all 3. Then I reply - show me, let's work together week or two, and show me how. They never did.

 

[AgX]

Isn't Schmidt design including a freeform lens?

No, but an aspheric element. I is a of peculiar shape, wavy in radial section, but still rotational symmetric.

 

[alanrockwood]

No, but an aspheric element. I is a of peculiar shape, wavy in radial section, but still rotational symmetric.

As you may know, the corrector plate was originally made using by regrinding a glass plate that was deformed by applying a vacuum to one side.