Purpose:
Adaptive liquid lens with tunable power has important applications in vision care and depth-resolved three-dimensional (3D) eye imaging. The current phoropter used by eye care professionals during an eye examination contains two lens wheels with a group of lenses in 0.25 diopter increment to measure the individual’s refractive error. By using a tunable lens, a single integrated lens can replace the conventional phoropter. In addition, by incorporating the tunable liquid lens into a compound objective lens design with variable focal length, a nontranslational depth-resolved 3D microscope can be constructed for eye and general biomedical imaging. We would like to develop an electro-optic tunable liquid lens and demonstrate its applications.
Methods:
For the first time to our knowledge, we have designed and fabricated a tunable liquid lens with large aperture, low driving voltage and fast response time. The lens is actuated by electromagnetic force. Two apertures serving as the reservoir and the lens chambers in a plastic substrate are connected by a channel. The top surfaces of the two chambers are covered by PDMS membrane. By applying a DC voltage, the shape of the membrane of the lens can be controlled and the power is tuned. By manipulating the shape of the lens aperture, both spherical and cylindrical powers can be obtained. The lens can be used for vision test directly and a confocal imaging system with varifocal objective lens has been built for 3D imaging.
Results:
The electro-optic liquid lens with an aperture larger than 10 mm shows large tunable power (up to 43.7 diopter) and the required DC voltage is only a few volts (less than 5.3V). Other characterizations of the lens has been performed, including the response time, wavefront, higher-order aberration, modulation transfer function, off-axis imaging property, and chromatic aberration. Vision test results will be presented. The nontranslational confocal imaging system has a field of view of 1mm×1mm, transverse resolution of 2µm, and a depth scanning range of 1mm.
Conclusions:
The electro-optic tunable liquid lens is very promising for visual tests and depth-resolved 3D microscopic imaging systems.
Keywords: spectacle lens • presbyopia • microscopy: confocal/tunneling