Simultaneous measurement of the shape and thickness of a dragonfly wing

Abstract

A new method has been developed to measure the thickness and shape of a dragonfly wing simultaneously. The innovation in the method, which we call the TSM (thickness and shape measurement) method, is the combination of a heterodyne interferometer and a laser triangulation displacement sensor into one optical system. We confirmed the accuracy of the method by measuring the displacement of a glass plate and the thickness variation generated by a tilted glass plate. The method was then applied to a tilted glass plate and a dragonfly wing. The TSM system has a relative accuracy of 1% in the shape measurement and 1.8% in the thickness variation measurement. The results indicated that the method is very effective in biomechanics studies, such as evaluating the flight performance of dragonflies. In such evaluations, it is essential to measure with high accuracy the variations in both shape and thickness of the wing simultaneously.