A lens bench for measuring the modulation transfer function

The need for a lens tester arose several years ago in connection with many projects associated with the Russian-English Translator, being built jointly by the United States Air Force and IBM Research. In order to determine if the lenses in the various components of the system were performing up to their specifications, and to resolve doubts as to their stability under high accelerations, a lens tester was designed and built according to the following specifications: 1. The machine must be able to test a variety of lenses at finite, but adjustable, conjugates. 2. Accuracy of the order of two percent, and repeatability of the order of one-half percent, were demanded. 3. The total elapsed time for one set of readings, from completion of the setup to reduction of the data, should not be more than one-half hour. b. The results should be in such a form as to be convenient for computations of entire system performance, and not merely for lens evaluation. The device was envisioned as the center of an optical engineering laboratory, with adequate computing facilities available. © 1967, SPIE.