Abstract: A graphic input system for digitizing the location of an object moving on a planar surface and utilizing two or more primary laser light beams, the output beam of each scanning the planar surface through interposed controllably pivotally mounted beam deflecting scan mirrors. A stylus is moved over the planar surface in response to the position of the deflected position of the scanning beam. A signal generating beam detector positioned adjacent the planar surface delivers signals to a logical circuit to create the instantaneous value of a position voltage signal which is proportional to the tangent of the scan angle of each of the controllably deflected laser beams.

Abstract: In the field of non-destructive evaluation of materials, conventional ultrasonic measurement techniques are limited to materials having a thickness which is relatively large compared to the wavelength of the ultrasonic signal used. The present technique enables the accurate ultrasonic non-destructive measurement of materials which are relatively small compared to the wavelength of the ultrasonic signal used. Ultrasonic signals received from a thin material are processed in the frequency-domain either directly or by use of a Fast Fourier Transform. Specifically, the frequency response of the ultrasonic transducers used in the measurement is removed from the frequency response of the signal received when measuring the material. This yields a frequency response which is indicative of the material alone. Then, the measured frequency response of the material is evaluated to determine unknown parameters of the material.