Figure 1.

(a) 3D rendering of the used sample. The shading within one branch indicates an increasing, decreasing thickness, respectively. The frame and the semicircle on the upper frame have a constant thickness. Its overall dimension is 42.5 × 42.5 mm and was made of a polyacrylic mixture using stereolithography. The red frame marks the area which is presented in this work. The images (b,c) show a section of the object image and reference image number one. The Moiré stripes are tilted slightly clockwise from the horizontal axis. The scale indicates the size in the detector plane.