Surface profiling of an aspherical liquid lens with a varied thickness membrane

Abstract

Inspired by crystalline lenses in human eyes, liquid lenses have a simple yet elegant working principle, and result in compact optical systems. Recent numerical studies showed that membranes with variable thicknesses could affect the lens profile. However, fabrication and assembly of a liquid lens with an inhomogeneous membrane is difficult. There is also a lack of experimental studies about the changes of a lens profile during deformation. In this paper, we provided a new experimental approach for characterizing the performance of a liquid lens with an inhomogeneous membrane. A 2D axisymmetric lens model was built in finite element analysis software to theoretically study the non-linear deformation behavior of the inhomogeneous membrane. Then we provided a new approach to fabricate inhomogeneous membranes using a pre-machined aluminum mold. An optical coherence tomography (OCT) system was used to dynamically measure the changes of a lens profile without contact. Both simulation and the experiments indicated that the variation of the thickness of the membrane could affect the lens profile in a predictable manner. A negative conic constant was achieved when a plano-concave membrane was adopted in a liquid lens. Larger increments of the thickness of the membrane in the radial direction resulted in a larger contribution of a conic constant to the lens profile. The presented study offers guidance for image-quality analysis and optimization of a liquid-lens-based optical system.

Color tunable pressure sensors based on polymer nanostructured membranes for optofluidic applications

“…An extended method for tuning membrane based optofluidic devices is through the internal gas or liquid pressure. For example, the fabrication of focus tunable lenses, by changing the membrane deformation, has become an extended method for the development of adaptive optics 2–4 . Different optical detection methods have been applied for measuring the integrated membrane deformation 5–7 .…”

Progressive Multifocal Liquid Lenses Based on Asymmetric Freeform Surface Structure of Nonuniform Thickness Elastic Membranes with Different Constraints

“…In order to reduce gravity effects to the performance of liquid lens, one method used an inplane pretention force onto the membrane to take the place of surface tension and another used a nonuniform thickness profile of flexible membrane [17,18]. Furthermore, the focus-tunable liquid lenses using nonuniform thickness membranes are also introduced and have some advantages compared with the lens with a uniform thickness membrane of alleviating the edge clamping effect, reducing spherical aberration and improving optical resolutions [19][20][21][22][23].…”

Ultrathin Tunable Lens Based on Boundary Tension Effect

“…These lenses are also widely used to design various optical systems, such as 3D displays [11], zoom systems [12,13,14], microscopes [15,16,17], endoscopes [18], and bionic human eyes [19]. However, electrowetting liquid lenses [16,20,21,22] and membrane liquid lenses [23,24,25] require suitable liquid thickness [26]. Thus, further reducing the lens volume is difficult.…”