An introduction to optical membranes.

Research has been conducted on optical membranes which consist of an organic substrate overlaid by a layer of evaporated metal. Antimony, zinc, and arsenic have been investigated, and other metals briefly tried. Most metallized membranes exhibit a slow decrease of tension and sometimes this tension becomes a compression, at which point the membrane becomes creased or wrinkled and loses its optical property. Membranes of celluloid metallized with arsenic have been found to be the least subject to that defect, and to have a useful service life of the order of ten years when installed in a pneumatic ir detector, while having a nearly indefinite life when kept on the shelf.