Grid

I'm wondering what sort of grid I could make with a pin instead of an extruder head mounted to the Ultimaker, and poking a piece of tin foil with the Z-axis. With steps of 0.05 mm (1/16th micro stepping) that's 20 holes per millimeter (508 dots per inch). If the hole size is comparable to the spacing, it could make a good 2D diffraction grating.

What sort of frequency are we talking here? For single dimension diffraction, d(sinΘ + sinδ) = mλ, where d is the grid spacing, the sin elements are incidence and maxima angles, m is an integer and λ is the wavelength of radiation. So for interesting (large) angles, say 5 and 45 degrees, within the brackets is about 0.80. For a d of 0.05mm, and considering the first maxima distance, λ = 0.0625 mm or 6.25e-5 meters. This is deep in the infrared.