Mechanical modeling of fluid-driven polymer lenses

Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, Florida 33124, USA.
Applied Optics (Impact Factor: 1.78). 08/2008; 47(20):3658-68. DOI: 10.1364/AO.47.003658
Source: PubMed


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.

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    • "In these days the field of optical elements with variable focal length based on different physical principles is rapidly developing [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]. One possible way to realize a variable-focus lens is to use a thin elastic membrane clamped at the edge as one optical surface of a liquid lens of appropriate construction [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]. Fig. 1 shows a simple scheme of such a lens. "
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    • "The surface contour of lens as well as its optical performance fabricated with molding method is determined by the master mold. Since the elastomeric master mold adopted here actually has the same structure as the widely described liquid lens, the detailed discussion on mechanical deformation characteristic and the corresponding optical performance can be found in Ref. [15]. The focal length of the fabricated concave lens (as shown in Fig. 2(e)) under different pressures applied during molding process is first measured . "
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