Re: Fourier Optics Defocus Question

"@(nospam)rmc.ca" <""harry.ingleby\"@(nospam)rmc.ca"> wrote:

>Hi all,
>
>Quick question.  I know that, in a wave optics representation of 
>imaging, shifting the detector away from the "true" image plane can be 
>treated as a quadratic defocus term in the optical phase at the exit pupil.
>
>Now for the question: if instead of shifting the detector, I shift the 
>object position away from the "true" plane, is the defocus still a 
>quadratic?
>
>Thanks,
>Harry
>
>PS This is not a homework question.  I took Fourier Optics a few years 
>back, and I know that if I haul out my copy of Goodman, I can probably 
>work this out. Just wondered if anyone has the answer off the top of 
>their head.

Yes and no, it depends. If the optical system OPD map generated by the
ray trace has design residual aberrations which vary significantly as
the object position changes, then these aberration changes will be
present along with the added quadratic term.

Jim Klein
West Coast Engineering
www.westcoastengineering.com