PROCESS AND DEVICE FOR NON-CONTACT DETERMINATION OF THE MASS PER UNIT AREA OF THIN MATERIALS

摘要

The patent claim describes a process for non-contact determination of weight per unit area and thickness of thin materials. This involves directing an ultrasonic wave at the material and measuring the proportion of sound energy that passes through the material. The process is distinguished by the fact that the time intervals between the ultrasonic pulses are greater than the propagation time. At the receiver only the signals that exceed a certain amount and are shorter in duration than the propagation time are evaluated.