Fig. 3

Schematic evolution of our grating design from regular gratings. The images show the real-space structures a–c and respective diffraction pattern d–f. a A regular grating diffracts incoming light to two symmetric points in Fourier-space d and hence reveals no spatial information on the illumination function. b A two-by-two segmented grating yields two symmetric sets of four diffraction spots e. The intensity of each spot is proportional to the illumination of the corresponding sample quadrant. This constitutes the most basic form of a spatially resolving beam profile monitor based on an integrated grating. c A grating with suitably varying period and orientation forms a magnified image of its own illumination in Fourier-space f. The colors in the real-space images indicate the local grating period and mark the corresponding points in the diffraction images