Photoreceptor prodn. with multi-chroitic colour strip filter - useful for coding and decoding using photoresist and vapour deposition of interference layers

摘要

In the prodn. of a photoreceptor with a multichroitic colour strip filter, the interlocked filter strip systems are applied in consecutive process stages, each involving coating the substrate with photoresist, exposing through a suitable mask, developing the photoresist, vapour deposition of the desired interference film for the filter colour concerned and then removing the remaining photoresist. The photoreceptor is useful for coding and decoding. Filters with very steep sided spectral transmission curves can be produced. Pref. the photoresist and overlaying superfluous filter film is lifted off by swelling with organic solvent, pref. dimethyl ketone. A positive resist with a thickness of min. 1 micron is used. Chemically and mechanically stable materials, e.g. highly refractive materials such as Ta205, TiO2, ZnS etc., or materials with low refraction such as MgF2, SiO2, ThO2 etc., are used to produce the filter layers. The substrate is a plane-parallel glass plate, which is aligned with the photoreceptor, or the photoreceptor itself. The filter strips can be longer than the width of the effective area of the photoreceptor.