Tech Briefs

This system demonstrates non-mechanical zoom using flexible thin films.

A breadboard system has been developed for demonstrating nonmechanical zoom using flexible thin films. The project consists of three major task areas: material characterization, diagnostic system development, and imaging system development. The material characterization phase involves two components: development of modeling tools, and measurement of material properties for use in the tools. The diagnostic system development phase will apply the tools and knowledge developed in the first phase to build algorithms for modeling and testing one-dimensional films with multiple actuators. These models will then be compared to experimental results and modified as needed. The imaging system development phase will conclude the effort by building a sensor system with variable zoom based on optical-quality PVDF films.

A COMSOL deformation plot for an initial gradient Piezoelectric Model (deformation is exaggerated by 7.5X). Overall dimensions are 2 mm × 2 mm × 50 μm.
The modeling tools are based on interaction among three commercial software packages: SolidWorks, COMSOL Multiphysics, and ZEMAX optical design. SolidWorks is a computer-aided design package, which has a live interface to COMSOL, which is a finite element analysis/partial differential equation solver. ZEMAX is an optical design package. Both COMSOL and ZEMAX have live interfaces to MATLAB. A model in SolidWorks can be updated in COMSOL, an FEA calculation performed in COMSOL, and data exported to MATLAB. Independently, surface profile data has been exported from MATLAB into ZEMAX. The next step will be to connect a single model from SolidWorks to ZEMAX. From MATLAB, the optical data will be used to alter the voltages driving the surfaces in COMSOL, and the cycle repeated. This will enable the development of approximations at a future time.

Modeling has focused on developing an empirical model for the film behavior and incorporating it into COMSOL. In the past, PVDF actuators were formed by combining two layers of materials that were poled with different orientations. The materials then act like a bimetallic strip used in a thermostat. Given the same field, one layer of the bimorph material would expand and one layer would contract, resulting in a curvature. This process is not amenable to opticalquality films because of the distortion created by attaching the two films.