Optical filter with multiple layer interference filter e.g. for semiconductor manufacture

摘要

An optical filter with a multiple layer interference filter on a substrate ensures that radiation of at least one emission line or spectral range is reflected and radiation of other spectral ranges is transmitted. The transmission in the wavelength range of 434 to 500.7 nanometres and/or 484 to 486.1 nanometres and/or 654 to 656.3 nanometres is much less than in the rest of the overall range of 160 to 1200 nanometres. The filter has 8 high- and 7 low-refracting layers, the refractive index of the former being 2.35 and of the latter being 1.35. Quartz glass is used for the substrate. The filter is used in astronomical telescopes to damp out the emission lines of nebulae in space.