Measuring the camber deformation of a dragonfly wing using projected comb fringe

The camber deformations of the flapping insect wing provide important infor mation for lift force analysis. Recent measurements are nearly all based on the hypothesis of the rigid wing, neglecting the camber deformation. In th is article, a measurement system based on fringe pattern projection is intr oduced. Projected comb fringes, whose intensity function is near a comb fun ction, were used instead of conventional sine fringes because of their high intensity and sharpness, allowing us to take the distorted fringes on the transparent dragonfly wing easily. The camber deformation and torsion angle of a flapping dragonfly wing can be measured without hypothesizing that th e wing is a rigid plate. The experimental result shows that the camber defo rmation is different during upstroke and downstroke. It is very important f or the explanation of the lift force. (C) 2001 American Institute of Physic s.