Design and simulation of a tunable fresnel lens with initial experimental validation

We investigate a mechanically tunable Fresnel lens whose focal length and resulting wavefront shape can be adjusted by controlled deformation of the substrate. A coupled simulation workflow links finite element modeling with optical design to map applied substrate distortion to the resulting optical performance. Deformed surface profiles generated by applying radial forces to the lens are modeled in Ansys Mechanical and transferred to Ansys Zemax to evaluate changes in focal length, wavefront error, and spot quality. To validate the simulations, a laboratory setup with a manually adjustable holder is implemented. A Fresnel lens fabricated from polydimethylsiloxane (PDMS) is mounted in a custom frame enabling defined radial displacement. A collimated beam and a camera-based detection system are used to characterize the focal plane. The results demonstrate a reproducible and predictable tuning behavior, with good agreement between simulation and experiment, highlighting mechanical deformation as a simple and effective approach for tunable Fresnel optics.