Film transport and liquid gate for an optical data processing system

A film transport has been designed, with the capability of positioning a specific five-inch segment of a 200 foot roll of 35 mm film in the input window of a coherent optical data processing system. The output of this system is the power spectrum of one of up to twenty channels of analog data pre-recorded on the film in the form of optical density variations. The optical window built into the transport is a liquid gate which functions to eliminate inherent system nonlinearities caused by irregularities in the film microstructure. Polyethylene glycol was the liquid selected for use in the liquid gate. The desired segment of film is identified by a pre-recorded sixdigit code. A fiber optic read head located to the edge of the window senses this code and transforms it into signals compatible with standard TTL integrated circuitry, which can be used for automatic microcomputer control of the system.