Figure 4
Comparison of visibility variation along the optical axis for basic (45° and 125° direction) and mixed harmonics (0° and 90° direction) for π/2 diamond (a) and π Si (d) phase checkerboard gratings. The pitch in the diagonal direction was 2.8 µm for the diamond grating and 2.725 µm for the Si grating. Vertical lines in the graphs represent the theoretical positions for the Talbot distances (black) and fractional Talbot distances for basic (red) and mixed (green) harmonics. The interferograms (b,c,e,f) shown are taken from the first maxima for the basic harmonics. The scale bar represents 100 µm. For the analysis of the visibility the area marked with red squares in (b) and (e) was used. The locations and sizes of these regions of interest were chosen for visibility analysis based on the nearly uniform illumination within these areas. |