Studying Kiwifruit with Laser Ultrasound and Seismology Techniques
Résumé
The elastic properties of fruit can be directly related to their quality, age, and composition. Almost all methods used to probe these properties are destructive, involving either compression or outright penetration of the fruit. In contrast, elastic waves offer a natural and potentially non-destructive method for fruit monitoring. Recently, we showed that quantities such as the elastic modulus and Poisson?s ratio can be measured in fruit using laser- generated and laser-detected elastic waves ? a completely non-destructive and non-contacting method. Here, we discuss these types of measurements on golden kiwifruit of varying quality. Our experimental setup involves rapid scanning of a laser Doppler vibrometer detection point around the hemisphere of the kiwifruit. This enables reliable measurements of wave speed and attenuation. We use attenuation values to distinguish between fruit of differing quality, even when such differences are not evident from the fruit?s exterior. Perhaps more interestingly, however, these datasets of elastic waves in ellipsoid fruit can be seen as directly analogous to those obtained in seismology. Both surface and body waves can be observed and their velocities measured, and a range of resonant modes identified. We discuss this rich set of information obtained from simple measurements on ellipsoid fruit.
Origine : Fichiers éditeurs autorisés sur une archive ouverte