Lithographic mirrors: Measured with sub-nanometre accuracy

Future generations of microchips will probably be produced using extreme ultraviolet light with a wavelength of thirteen nanometres. Optical lenses will no longer be suitable for the manufacturing process because they absorb the light at such short wavelengths. Mirrors will have to be used instead. Currently the main problem is the required precision to accurately determine the curvature of the mirror down to the nanometre. Researchers at TU Delft have built a new measurement system that promises to achieve just such a precision: an absolute interferometer. This new measurement system offers many advantages over competing methods