A finite-element model (FEM) is employed to study the pressure response of deformable elastic membranes used as tunable optical elements. The model is capable of determining in situ both the modulus and the prestrain from a measurement of peak deflection versus pressure. Given accurate values for modulus and prestrain, it is shown that the two parameters of a standard optical shape function (radius of curvature and conic constant) can be accurately predicted. The effects of prestrain in polydimethylsiloxane (PDMS) membranes are investigated in detail. It was found that prestrain reduces the sensitivity of the membrane shape to the details of the edge clamping. It also reduces the variation of the conic constant with changes in curvature. Thus the ability to control the prestrain as well as thickness and modulus is important to developing robust optical designs based on fluid-driven polymer lenses.
© 2008 Optical Society of America
Original Manuscript: March 13, 2008
Revised Manuscript: June 4, 2008
Manuscript Accepted: June 10, 2008
Published: July 9, 2008
Vol. 3, Iss. 8 Virtual Journal for Biomedical Optics
Qingda Yang, Paul Kobrin, Charles Seabury, Sridhar Narayanaswamy, and William Christian, "Mechanical modeling of fluid-driven polymer lenses," Appl. Opt. 47, 3658-3668 (2008)