Scientific apparatus, namely, silicon nitride, silicon carbide, boron nitride and polysilicon membranes for use in the science and research industry; X-ray apparatus not for medical purposes, namely, x-ray filters for filtering out some or all wavelengths in the x-ray spectrum; diffractive optics being thin optical elements such as gratings and zone plates that operate by means of interference and diffraction to manipulate light to a selected intensity profile, including beam shapers, beam sp...