Filters for the Isolation of Narrow Regions in the Visible and Near-Visible Spectrum

Abstract

A description is given of the prepn. of dyed gelatin filters, 60 cm. square and larger, with precisely controlled transmission characteristics. Details are presented for the prepn. of the dye-gelatin solns., casting of the films on silicone-treated plate glass, and removal of the large sheets from the glass. Formulas and transmission curves are given for 15 long wave pass and 9 band pass filters covering the near ultraviolet, visible, and near infrared. Transmission curves are given for the visible and near infrared transmission of water in path lengths of from 1 to 30 cm., and of various concns. of ferrous ammonium sulfate and copper sulfate in 10 cm. path lengths.