Figure 2.

Representation of the studied Fresnel lens: (a) 3D view of the flat, squared, 40 mm × 40 mm Fresnel surface aperture, with a section view of the axis-symmetric radial profile, which follows a stepped aspheric profile as described by the conic equation; (b) a highlight of the section profile in the z, r plane with indication of the peak-to-valley (PV) nominal specifications in comparison with the equivalent continuous aspheric curvature; (c) summary table of the aspheric properties of the considered lens.