Axisymmetrical resonance modes in an electrowetting optical lens

Abstract

Electrowetting-based adaptive optics are of great interest for applications ranging from confocal microscopy to LIDAR, but the impact of low-frequency mechanical vibration on these devices remains to be studied. We present a simple theoretical model for predicting the resonance modes induced on the liquid interface in conjunction with a numerical simulation. We experimentally confirm the resonance frequencies by contact angle modulation. They are found to be in excellent agreement with the roots of the zero-order Bessel functions of the first kind. Next, we experimentally verify that external axial vibration of an electrowetting lens filled with density mismatched liquids (Δρ = 250 kg/m3) will exhibit observable Bessel modes on the liquid–liquid interface. An electrowetting lens filled with density matched liquids (Δρ = 4 kg/m3) is robust to external axial vibration and is shown to be useful in mitigating the effect of vibrations in an optical system.

Tunable liquid lens for three-photon excitation microscopy

“…To measure this, we pass a 2 mm diameter 632.8 nm incident laser beam (HeNe) through the center of our electrowetting lens and onto a photodetector (Thorlabs DET36A) with a 50 μ m pinhole on the front. As we actuate our device, a capillary wave is generated along the liquid-liquid meniscus [ 72 – 74 ]. These oscillations are recorded as a change in intensity over time on our photodetector.…”