  The mechanical properties of a kiwifruit are investigated via non-contact
acoustic measurements. Transmitted ultrasonic waves are measured using a static
laser source and a rotating laser ultrasound detector. The measurements enable
observation of a low-frequency surface wave and a higher frequency direct wave;
combined with seismology-inspired theoretical modeling, these measurements
enable estimation of several elastic parameters for inner and outer fruit flesh
layers. Results indicate that the surface and direct wave velocities and the
bulk and Young's moduli all evolve with fruit age/ripeness, while only the
direct wave velocity and bulk modulus differ significantly between outer and
inner fruit layers.
