Hi Yifan,

Zernike Standard Coefficients and Zernike Fringe Coefficients are defined on a unit circle. By default, they are determined for the entire pupil, but the subaperture values Sx, Sy, and Sr allow computation of the Zernike data only over a circular subaperture portion of the pupil.

However, when performing a fit for each of these analyses, OpticStudio will only use data points defined over that elliptical region that is the pupil. That is, OpticStudio will map the unit circle into the ellipse that defines the maximum extent of the rays that OpticStudio launches through the system.

Hi Berta,

Thank you for your help !

I still have a question, what does 'map the unit circle into the ellipse' mean? Stretch the ellipse into circle?

Or just add some “0”data ，fuifill the ellipse into circle?

Yes, fulfill the ellipse into the circle so the semi-major axis of the elliptical pupil and the radius of the unit circle over which the Zernike fit is applied are equal. Something like this:

Thank you again!

Hello all,

I would like to come back on this subject. Does it mean that when your system is vignetting so the exit pupil is not a circle, Optic Studio will calculate the Zernike polynomial on a circle which includes the vignetted pupil ? Or the pupil is diformed to become a circle ?