Photoreceiver with polychromatic colour band filter - made by successive applications using photolacquer at each stage

摘要

Method of making a photo-receiver with a polychromatic colour band filter is as follows. The alternating filter bands are laid on a substrate, typically of glass, in successive stages; in the first stage, the substrate is coated with a continuous photo lacquer, this is then exposed and developed using a grating of parallel lines to give intermittent parallel strips of lacquer (top view); then the first filter layer is laid entirely over the lacquer and the substrate (centre view), then the photo lacquer together with the layer of filter overlying it is removed, esp. using organic solvents, pref. dimethyl ketone, to give strips of the filter material only (bottom view). The process is then repeated, by again applying photo lacquer over the filter layers and substrate, removing the lacquer in intervening spaces, then applying the second filter layer, then removing the photo lacquer together with the overlying second filter layer, thus giving two different filter strips alternating. The process may be repeated with as many strips as desired. Pref., to produce the filter layers, chemically and mechanically stable evaporating materials, e.g. highly refractive materials such as Ta2O5, TiO2, CeO2, ZnS are used, and/or low-refractive materials such as MgF2, SiO2, ThO2. Photoreceivers or photo sensors with absorption-free, polychromatic colour band filters having very sharp characteristics and steep-flanked spectral transmission are obtained.