Fig. 3

Optical micrographs of developed exposures in S1805 resist (all images are at the same magnification and the scale bar of (a) 200 μm): a a single exposure of the mask (inset: profile from dashed line), b a double exposure where the mask has been moved 100 μm in the transverse direction to the grating between exposures, c a triple exposure where the mask has been moved in 65 μm steps in the transverse direction to the grating between exposures, d a double exposure where the mask has been moved 30 μm in the transverse direction to the grating between exposures to create a 10 μm wide protrusion (inset: profile from dashed line), e a double exposure where the mask has been moved 20 μm in the transverse direction to the grating between exposures to widen the grating features and f a double exposure where the mask has been moved 7 mm in the direction of the grating between exposures to double the length of the features (the dashed black line indicates the stitch position). (Inset) ×2 magnified close-up of the stitch position for one line of the grating