A Mosaic Filter Daylight Source for Aerophotographic Sensitometry in the Visible and Infrared Region

Abstract

An unconventional filter is described which converts the light of a tungsten lamp of 2660°K color temperature to daylight. The filter consists of 169 small Corning glass filters, each 3 by 3 mm in size and cemented, in the form of a mosaic, on a common glass base. A good approximation to natural daylight is obtained in the region between 5200 and 9000 angstroms which enables panchromatic and infrared sensitometry through the entire region useful in general photographic reconnaissance. The new light source is compared with a number of other sensitometric light sources. Its spectral characteristics are superior to any of the other glass filter sources investigated.