A bleach process for high-efficiency low-noise holograms

A bleach process is described which gives high-efficiency, low-noise holograms. Potassium ferricyanide is used as the bleaching agent. The main differences between this process and earlier uses of potassium ferricyanide for bleaching are a different developer and a special drying procedure. The following values for the efficiency were obtained: 45% for a plane grating, 25% for a hologram of a diffuse subject, and between 10% and 15% for holograms of data masks. The bleached holograms are stable in an ordinary laboratory atmosphere but degrade in very high humidity.