Fig. 7.

Difference between the normalized spectra $\frac{\left|F\left(f_1{f}_2\right)(f)\right|}{\underset{f}{\max }\left|F\left(f_1{f}_2\right)(f)\right|}$ and $\frac{\left|F\left(f_2\right)(f)\right|}{\underset{f}{\max }\left|F\left(f_2\right)(f)\right|}$ for r′ ∈ [0,0.98R]. We have $\underset{f}{\max }\left|\frac{\left|F\left(f_1{f}_2\right)(f)\right|}{\underset{f}{\max }\left|F\left(f_1{f}_2\right)(f)\right|}-\frac{\left|F\left(f_2\right)(f)\right|}{\underset{f}{\max }\left|F\left(f_2\right)(f)\right|}\right|\le 4.5\times {10}^{-3}$ for any r′ ∈ [0,0.98R].