Optical diffraction grating based on porous materials

摘要

The diffraction grid has a sheet of porous material, e.g. porous silicon, whose optical characteristics vary with illumination with a first structure (5) on the illuminated side which performs spectral division or deflection of the incident light depending on phase variations of the transmitted or reflected light. The first structure can be formed over the entire sheet or exist in periodically varying regions. Interferogram are formed on the illumination side. At least one further structure can be formed on the illumination side with a periodically varying structure and different optical characteristics.