Figure 4

Parametric search for simultaneous minimization of δ_s and δ_p.

(a) Solid curves: z-positions at which the phase and shape errors minimize for the given (z_o, a). Lack of their intersection indicates that the two do not minimize simultaneously. Dashed curves: z_min,error values obtained by limiting the range for the shape error evaluation within ρ ≤ 1.3 μm, which enabled simultaneous minimization of δ_s and δ_p. (b) δ_p,min values as a function of (z_o, a). In general, δ_p grows rapidly as z_o moves away from CP. (c) Solid curves: δ_s,min values obtained when z_o = 33 ~ 36 μm, i.e., within 3 μm from the ending point of CP. Overall, δ_s values grow monotonically with a. Dashed curves: δ_s assessed only within ρ ≤ 1.3 μm. Now they exhibit definite dips, suggesting that the shape error accumulates mostly in the region with ρ > 1.3 μm, i.e., the area not covered by the distributed absorption shown in Fig. 3a.