A Motion-Picture Film Cue System Based upon Infrared Diffraction

A new cue system for motion-picture printers is based upon the incoherent diffraction of infrared radiation. It is completely interchangeable with and compatible with present RF and notch cue systems. Diffraction cues are placed on the film. The detector is on the printing machine. The punched paper tapes used to encode the printer light changes remain unmodified. A cue consists of inscribed, finely spaced parallel lines located in an area bounded by the edge of the film, the picture frame and the adjacent sprocket holes. A pattern of inscribed lines causes a “blaze” or sharp line of radiation to be incoherently diffracted in a direction orthogonal to the lines. The appropriately placed detector senses only the diffracted radiation when a cue passes into the optics. With solid-state electronics, signals are amplified, time delays injected (if desired) and the printer light changes triggered. The cues are inscribed on the film in 1 s by one battery-powered cue applicator.