The introduction of silicon foils in the field of X-ray optics has led to imaging optics of higher speed. This allows a better signal to noise ratio for X-ray experiments. In X-ray microscopy, lenses with higher speed result in shorter exposure times which means also less radiation load to the object. This is of great value for the investigation of biological specimens, in their natural wet state. For X-ray microscopes with pulsed X-ray sources it is important to use only one pulse to image the object in order to avoid image confusion by object movement. The improvement of the signal to noise ratio results in images of higher quality.
For electron spectroscopy, where up to 3 zone plates are used, not only is high efficiency wanted, but also radiation resistance is essential, as the relatively low effiency of zone plates results in a high radiation exposure of the first of the zone plates.
As vacuum windows, silicon foils are unique with respect to transmission. Foils with thicknesses of 70 nm are used to protect vacuum chambers against atmospheric pressure with an absorption of only 12% at 2.4 nm X-ray wavelength. Usually several vacuum windows are used in X-ray microscopes and other X-ray devices. Use of these high transmissive windows has the same effect as speeding up the optics.
For the production of X-ray optics, smooth, thin foils are essential if small structures are to be made. The produced micro zone plates with outermost zone widths of 30 nm on thin silicon foils are state of the art, and plates of 20 nm have been made.