Gerald M. Rassweiler

Recording and control system for infra-red spectrophotometer.

The recording system employs a contact-modulated amplifier and self-balancing potentiometer in an electrical null circuit including variable response speed and gain. The control system automatically adjusts the slits and zero at preselected prism positions. Familiar spectra illustrate the effects of variables such as slit width, recording speed, and response speed.

Ultrasonic Resonance Applied to Non‐Destructive Testing

Ultrasonic vibrations of continuously varying frequency are applied to the part under test which is set into longitudinal vibration at its natural frequencies. The consequent reaction on the applicator is used to produce visible marks on a cathode‐ray screen from which thickness of the part may readily be deduced.