Dynamic Liquid Optics

基于光流变学的可调谐光学的能力源于可控制地将液体界面变形为折射表面所需的形状的能力。使用电润湿作为一种驱动技术，已经证明了可调液体透镜、棱镜和扫描器，最近甚至已经表明可以产生具有可控光学像差的表面。其中许多发展的关键是使用了管状射流结构，该结构具有高密度的方位分布和可单独寻址的致动电极。然而，液体光学实现先进成像系统的能力还可以进一步扩展，DyaLO项目将试图展示一种全新的方法来可控地产生任意液体表面轮廓，即通过透镜中随时间变化的表面波。利用PI在之前的工作中开发的32电极管状透镜的独特能力，将从理论和实验上分析通过透镜光圈产生精确控制的行波和驻波的能力。受机械致动器在直径25米的波槽中产生的波形的启发，DyaLO项目将把这一概念转化为5 mm的液体透镜。预计这种动态表面波可以用来产生各种各样的表面特征，也可以产生非圆对称的表面特征，这是使用静态激励无法实现的。这种新颖的动态表面成形将与静态表面成形以及反馈稳定的界面定位相结合，以允许产生更大范围的光学自由曲面。将实时监测液体分布，并将直接补偿由于例如透镜的取向变化或系统振动而引起的界面变化。最终的目标将是一种液体透镜，它的驱动可以瞬间和连续地调整，以确保产生所需的轮廓。如果成功，动态表面波方法与静态界面整形相结合将为可调谐液体光学元件开辟全新的天地。

The power of tunable optics based on optofluidics stems from the ability to controllably deform liquid interfaces to a desired shape for a refractive surface. Using electrowetting as an actuation technique, tunable liquid lenses, prisms, and scanners have been demonstrated, and recently it has even been shown that surfaces with controlled optical aberrations may be generated. Key to many of these developments has been the use of a tubular fluidic structure with a high density of azimuthally-distributed and individuallyaddressable actuation electrodes. Yet the capabilities of liquid optics for realizing advanced imaging systems can be extended further, and the DynaLO project will attempt to demonstrate an entirely new means for controllably generating arbitrary liquid surface profiles, namely through time-varying surface waves in the lens. With the unique capabilities of the 32-electrode tubular lenses developed by the PI in prior work, the ability to generate precisely-controlled traveling and standing waves across the lens aperture will be analyzed theoretically and experimentally. Inspired by the wave patterns which can be generated in 25 m diameter wave tanks using mechanical actuators, the DynaLO project will translate this concept to a 5 mm liquid lens. It is expected that such dynamic surface waves can be used to generate a wide variety of surface features, also non-circularly-symmetric ones, which cannot be achieved using static actuation. This novel dynamic surface shaping will then be combined with static surface shaping as well as feedback-stabilized interface positioning to allow the generation of an even wider range of optical freeform surfaces. The liquid profile will be monitored in real time and interface variations due to, for example, orientation changes of the lens or system vibrations, will be directly compensated. The ultimate goal will be a liquid lens for which actuation can be instantaneously and continuously adjusted to assure that the desired profile is generated. If successful, the dynamic surface wave approach combined with static interface shaping will open entirely new horizons for tunable liquid optical components.