The Talbot self-imaging effect of amplitude gratings is afflicted with aberrations that distort the self-image. This occurs especially if the grating period p is only a few times larger than the illumination wavelength lambda. For example, for lithographic applications of the Talbot effect these aberrations lower the lateral writing resolution and should be minimized. Noponen found, however, some discrete ratios of p/lambda in the interval of 2.0 < p/lambda < 3 that are aberration-free. We generalize the definition of the Talbot distance to include oblique illumination and show how Noponen's discrete ratios can be shifted by it. In the second part, we look at ratios of p/lambda larger than 3, so that there are more than five diffraction orders behind the grating. For this region we present a method to find ratios of p/lambda with at least minimal aberrations and present some self-image examples that are of interest for lithographic purposes up to the range of p/lambda approximate to 12. (C) 2015 Optical Society of America
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