ABSTRACT
This chapter describes the wavefront aberration polynomials of Zernike. Similar to the Kingslake aberration polynomial, they are not explicitly dependent on the image height. The wavefront aberration polynomials can be referred to any reference sphere. The reference sphere that minimizes the separation from the aberration polynomials is obtained by adding to them the proper amount of the piston, tilts, defocusing terms, or a lower-order aberration polynomial. The advantage of expressing the wavefront by a linear combination of orthogonal polynomials is that the wavefront deviation represented by each term is a best fit. Then, any combination of these terms must also be a best fit. In practical systems, the wavefront deformation may be obtained by several different procedures, for example, by integration of the transverse aberration values, if they are measured, or by direct measurement of the wavefront deformations using interferometry at several discrete points over the exit pupil.
