Polynomial Fitting for can save a tremendous amount of time spent tolerancing.  For an initial tolerance analysis, ZEMAX can calculate multiple points within the defined tolerance range.  Using this data, how the criteria changes as a function of tolerance perturbation may be fit to a polynomial.  For subsequent calculations, ZEMAX can use the polynomial fit to evaluate the criteria rather than recomputing each and every tolerance over and over again.

REFERENCES

ZEMAX Optical Design Program User’s Guide, ZEMAX Development Corporation