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1. Telephoto-lens-based Optical Differentiation Wavefront Sensor for freeform metrology

   https://doi.org/10.1364/OE.443558  

   Swain, Biswa_R; Dorrer, Christophe; Qiao, Jie (November 2021, Optics Express)

   We report an Optical Differentiation Wavefront Sensor based on a telephoto lens system and binary pixelated filters. It provides a five-fold reduction in the system length compared to a 4fsystem with identical effective focal length. Measurements of phase plates with this system are compared to measurements performed with a commercial low-coherence interferometer. The telephoto-lens-based system can measure wavefronts with accuracy better thanλ/10 Root Mean Squared (RMS) atλ=633 nm. Experimental investigation shows that the system has a high tolerance to components alignment errors. 

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2. Microfabricated Low-Profile High Tunable LC Fresnel Lens for Smart Contacts

   https://doi.org/10.1109/IPC53466.2022.9975691  

   Banerjee, Aishwaryadev; Ghosh, Chayanjit; Karkhanis, Mohit; Deshpande, Adwait; Pourshaban, Erfan; Kim, Hanseup; Mastrangelo, Carlos H. (November 2022, 2022 IEEE Photonics Conference (IPC))

   Using high-performance LC (5CB) filled microfabricated refractive Fresnel chambers, we experimentally demonstrate a thin low-profile adaptive optical system with very high analog tunability (15.5 D) that can be integrated with an adaptive smart contact-lens system. 

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3. Microfabricated Low-Profile Tunable LC-Refractive Fresnel (LCRF) Lens for Smart Contacts

   https://doi.org/10.1364/CLEO_AT.2022.AW4C.3  

   Banerjee, Aishwaryadev; Ghosh, Chayanjit; Karkhanis, Mohit; Deshpande, Adwait; Pourshaban, Erfan; Kim, Hanseup; Mastrangelo, Carlos H. (January 2022, Conference on Lasers and Electro-Optics (CLEO))

   Using high-performance LC (E7) filled microfabricated refractive Fresnel chambers, we experimentally demonstrate a thin low-profile adaptive optical system with high analog tunability (2.1 D) that can be integrated with an adaptive contact-lens system. 

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4. MEMS-actuated metasurface Alvarez lens

   https://doi.org/10.1038/s41378-020-00190-6  

   Han, Zheyi; Colburn, Shane; Majumdar, Arka; Böhringer, Karl F. (October 2020, Microsystems & Nanoengineering)

   Abstract Miniature lenses with a tunable focus are essential components for many modern applications involving compact optical systems. While several tunable lenses have been reported with various tuning mechanisms, they often face challenges with respect to power consumption, tuning speed, fabrication cost, or production scalability. In this work, we have adapted the mechanism of an Alvarez lens – a varifocal composite lens in which lateral shifts of two optical elements with cubic phase surfaces give rise to a change in the optical power – to construct a miniature, microelectromechanical system (MEMS)-actuated metasurface Alvarez lens. Implementation based on an electrostatic MEMS generates fast and controllable actuation with low power consumption. The utilization of metasurfaces – ultrathin and subwavelength-patterned diffractive optics – as optical elements greatly reduces the device volume compared to systems using conventional freeform lenses. The entire MEMS Alvarez metalens is fully compatible with modern semiconductor fabrication technologies, granting it the potential to be mass-produced at a low unit cost. In the reported prototype operating at 1550 nm wavelength, a total uniaxial displacement of 6.3 µm was achieved in the Alvarez metalens with a direct-current (DC) voltage application up to 20 V, which modulated the focal position within a total tuning range of 68 µm, producing more than an order of magnitude change in the focal length and a 1460-diopter change in the optical power. The MEMS Alvarez metalens has a robust design that can potentially generate a much larger tuning range without substantially increasing the device volume or energy consumption, making it desirable for a wide range of imaging and display applications. 

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5. Axisymmetrical resonance modes in an electrowetting optical lens

   https://doi.org/10.1063/5.0141787  

   Miscles, Eduardo_J; Lim, Wei_Yang; Supekar, Omkar_D; Zohrabi, Mo; Gopinath, Juliet_T; Bright, Victor_M (May 2023, Applied Physics Letters)

   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. 

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