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Sieben M, Sauter D, Zappe H. Phase retrieval for the generation of arbitrary intensity distributions using an optofluidic phase shifter. OPTICS EXPRESS 2023; 31:36000-36011. [PMID: 38017759 DOI: 10.1364/oe.496598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 08/20/2023] [Indexed: 11/30/2023]
Abstract
An optofluidic phase shifter can be used to generate virtually arbitrary intensity patterns, but only if the phase shift generated by the controllably deformed fluidic surface can be appropriately defined. To enable this functionality, we present two phase retrieval algorithms based on neural networks and least-squares optimization which are used to determine the necessary phase profile to generate a desired target intensity pattern with high accuracy. We demonstrate the utility of the algorithms by showing experimentally the ability of an optofluidic phase shifter to generate arbitrary complex intensity distributions.
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2
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Gilinsky SD, Zohrabi M, Lim WY, Supekar OD, Bright VM, Gopinath JT. Fabrication and characterization of a two-dimensional individually addressable electrowetting microlens array. OPTICS EXPRESS 2023; 31:30550-30561. [PMID: 37710595 PMCID: PMC10544957 DOI: 10.1364/oe.497992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/08/2023] [Accepted: 08/11/2023] [Indexed: 09/16/2023]
Abstract
We demonstrate a two-dimensional, individually tunable electrowetting microlens array fabricated using standard microfabrication techniques. Each lens in our array has a large range of focal tunability from -1.7 mm to -∞ in the diverging regime, which we verify experimentally from 0 to 75 V for a device coated in Parylene C. Additionally, each lens can be actuated to within 1% of their steady-state value within 1.5 ms. To justify the use of our device in a phase-sensitive optical system, we measure the wavefront of a beam passing through the center of a single lens in our device over the actuation range and show that these devices have a surface quality comparable to static microlens arrays. The large range of tunability, fast response time, and excellent surface quality of these devices open the door to potential applications in compact optical imaging systems, transmissive wavefront shaping, and beam steering.
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Affiliation(s)
- Samuel D. Gilinsky
- Department of Electrical, Computer and Energy Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Mo Zohrabi
- Department of Electrical, Computer and Energy Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Omkar D. Supekar
- Department of Electrical, Computer and Energy Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Juliet T. Gopinath
- Department of Electrical, Computer and Energy Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, CO 80309, USA
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3
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Li Y, Zhang Z, Liu X, Li L, Li L. Adaptive liquid lens with controllable light intensity. OPTICS EXPRESS 2023; 31:21806-21815. [PMID: 37381269 DOI: 10.1364/oe.492227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 05/18/2023] [Indexed: 06/30/2023]
Abstract
An adaptive liquid lens with controllable light intensity is demonstrated, which can modulate both light intensity and beam spot size. The proposed lens consists of a dyed water solution, a transparent oil, and a transparent water solution. The dyed water solution is used to adjust light intensity distribution by varying the liquid-liquid (L-L) interface. The other two liquids are transparent and designed to control the spot size. In this way, two problems can be solved: the inhomogeneous attenuation of light can be achieved through the dyed layer, and a larger optical power tuning range can be achieved through the two L-L interfaces. Our proposed lens can be used for homogenization effects in laser illumination. In the experiment, an optical power tuning range from - 44.03 m-1 ∼ + 39.42 m-1 and an ∼ 89.84% homogenization level are achieved. Our proposed lens may also ease the vignetting problem in imaging systems.
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Miscles EJ, Lim WY, Supekar OD, Zohrabi M, Gopinath JT, Bright VM. Axisymmetrical resonance modes in an electrowetting optical lens. APPLIED PHYSICS LETTERS 2023; 122:201106. [PMID: 37214761 PMCID: PMC10195114 DOI: 10.1063/5.0141787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 04/29/2023] [Indexed: 05/24/2023]
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.
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Affiliation(s)
- Eduardo J. Miscles
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | | | - Mo Zohrabi
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | | | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
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5
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Zohrabi M, Lim WY, Gilinsky S, Bright VM, Gopinath JT. Adaptive aberration correction using an electrowetting array. APPLIED PHYSICS LETTERS 2023; 122:081102. [PMID: 36846091 PMCID: PMC9946697 DOI: 10.1063/5.0133473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 02/04/2023] [Indexed: 05/10/2023]
Abstract
We demonstrate a method that permits wavefront aberration correction using an array of electrowetting prisms. A fixed high fill factor microlens array followed by a lower fill factor adaptive electrowetting prism array is used to correct wavefront aberration. The design and simulation of such aberration correction mechanism is described. Our results show significant improvement to the Strehl ratio by using our aberration correction scheme which results in diffraction limited performance. Compactness and effectiveness of our design can be implemented in many applications that require aberration correction, such as microscopy and consumer electronics.
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Affiliation(s)
- Mo Zohrabi
- Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
- Author to whom correspondence should be addressed:
| | - Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Samuel Gilinsky
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
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Zhao P, Sauter D, Zappe H. Tunable fluidic lens with a dynamic high-order aberration control. APPLIED OPTICS 2021; 60:5302-5311. [PMID: 34263767 DOI: 10.1364/ao.425637] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 05/24/2021] [Indexed: 06/13/2023]
Abstract
Fluidic lenses based on electrowetting actuation are attractive for their wide focal tuning range, yet are limited by optical aberrations, either intrinsic to the lenses themselves or due to the optical imaging systems in which they are employed. However, the ability to control the meniscus shape that forms the lens refractive surface with a high degree of spatial accuracy will allow correction of and compensation for a wide range of these aberrations. We demonstrate here for what we believe, to the best of our knowledge, is the first time a tunable optofluidic lens controlled by 32 azimuthally placed electrodes for which most aberrations up to the fourth radial Zernike order may be corrected. Using both wavefront sensing and sensorless wavefront estimation techniques, it is shown that focal length tunability with a significant reduction in imaging aberrations and the ability to compensate for externally induced aberrations may be achieved using a single component.
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Zhang W, Zhao R, He Y, Ding W, Liang Z, Kong M, Chen T. Electrowetting-actuated optofluidic phase modulator. OPTICS EXPRESS 2021; 29:797-804. [PMID: 33726308 DOI: 10.1364/oe.406140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 10/19/2020] [Indexed: 06/12/2023]
Abstract
In this paper, an optofluidic phase modulator based on electrowetting is presented. The modulator consists of an inner and outer chamber. Two immiscible liquids are filled into the chambers, and a transparent sheet is fixed between the liquid-liquid interface to obtain a flat interface. By applying different voltages to the modulator, the flat interface moves up and down leading to the change of optical path length. Consequently, the variation of the optical path in the proposed modulator exploits the ability to alter the optical phase. To prove the concept, a prototype of the phase modulator is fabricated in experiment, and the ability of phase modulation is detected. Our proposed modulator performs optical phase shift up to ∼6.68 π driven with 150 V. Widespread applications of such an optofluidic phase modulator is foreseeable.
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Electrowetting lens with large aperture and focal length tunability. Sci Rep 2020; 10:16318. [PMID: 33004850 PMCID: PMC7530674 DOI: 10.1038/s41598-020-73260-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 08/31/2020] [Indexed: 11/09/2022] Open
Abstract
The electrowetting lenses has attracted researchers in many fields, such as biology, beam shaping, and drug delivery. Previous research on electrowetting lens has focused on neither expanding the dynamic focal length range nor reducing the wavefront aberration. However, the properties with large numerical aperture and low aberration are also essential properties of lenses, and can promote their application. Therefore, we calculated the meniscus of the lens with different optical apertures, and subsequently, analyzed the relations among the focal length, wavefront aberration, and optical aperture. To expand the focal length range, we designed an electrowetting-based triple-liquid lens with a root-mean-square wavefront aberration error of less than 1/4 waves.
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Lim WY, Zohrabi M, Gopinath JT, Bright VM. Calibration and characteristics of an electrowetting laser scanner. IEEE SENSORS JOURNAL 2020; 20:3496-3503. [PMID: 33746623 PMCID: PMC7977153 DOI: 10.1109/jsen.2019.2959792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We present a calibration method to correct for fabrication variations and optical misalignment in a two-dimensional electrowetting scanner. These scanners are an attractive option due to being transmissive, nonmechanical, having a large scan angle (±13.7°), and low power consumption (μW). Fabrication imperfections lead to non-uniform deposition of the dielectric or hydrophobic layer which results in actuation inconsistency of each electrode. To demonstrate our calibration method, we scan a 5 × 5 grid target using a four-electrode electrowetting prism and observe a pincushion type optical distortion in the imaging plane. Zemax optical simulations verify that the symmetric distortion is due to the projection of a radial scanning surface onto a flat imaging plane, while in experiment we observe asymmetrical distortion due to optical misalignment and fabrication imperfections. By adjusting the actuation voltages through an iterative Delaunay triangulation interpolation method, the distortion is corrected and saw an improvement in the mean error across 25 grid points from 43 μm (0.117°) to 10 μm (0.027°).
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Affiliation(s)
- Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309 USA
| | - Mo Zohrabi
- Department of Electrical Engineering, University of Colorado, Boulder, CO 80309 USA
| | - Juliet T Gopinath
- Department of Electrical Engineering and Department of Physics, University of Colorado, Boulder, CO 80309 USA
| | - Victor M Bright
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309 USA
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Zohrabi M, Yang Lim W, Bright VM, Gopinath JT. High extinction ratio, low insertion loss, optical switch based on an electrowetting prism. OPTICS EXPRESS 2020; 28:5991-6001. [PMID: 32225857 PMCID: PMC7347523 DOI: 10.1364/oe.381565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/09/2020] [Accepted: 01/11/2020] [Indexed: 05/13/2023]
Abstract
An optical switch based on an electrowetting prism coupled to a multimode fiber has demonstrated a large extinction ratio with speeds up to 300 Hz. Electrowetting prisms provide a transmissive, low power, and compact alternative to conventional free-space optical switches, with no moving parts. The electrowetting prism performs beam steering of ±3° with an extinction ratio of 47 dB between the ON and OFF states and has been experimentally demonstrated at scanning frequencies of 100-300 Hz. The optical design is modeled in Zemax to account for secondary rays created at each surface interface (without scattering). Simulations predict 50 dB of extinction, in good agreement with experiment.
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Affiliation(s)
- Mo Zohrabi
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Juliet T. Gopinath
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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Mishra K, Narayanan A, Mugele F. Design and wavefront characterization of an electrically tunable aspherical optofluidic lens. OPTICS EXPRESS 2019; 27:17601-17609. [PMID: 31252717 DOI: 10.1364/oe.27.017601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 04/06/2019] [Indexed: 06/09/2023]
Abstract
We present a novel design of an exclusively electrically controlled adaptive optofluidic lens that allows for manipulating both focal length and asphericity. The device is totally encapsulated and contains an aqueous lens with a clear aperture of 2mm immersed in ambient oil. The design is based on the combination of an electrowetting-driven pressure regulation to control the average curvature of the lens and a Maxwell stress-based correction of the local curvature to control spherical aberration. The performance of the lens is evaluated by a dedicated setup for the characterization of optical wavefronts using a Shack Hartmann Wavefront Sensor. The focal length of the device can be varied between 10 and 27mm. At the same time, the Zernike coefficient Z40, characterising spherical aberration, can be tuned reversibly between 0.059waves and 0.003waves at a wavelength of λ=532nm. Several possible extensions and applications of the device are discussed.
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Schipf DR, Wang WC. Measurement and modeling of electrowetting lens oscillations using digital holographic interferometry and Bessel and Legendre polynomial functions. OPTICS EXPRESS 2019; 27:17274-17282. [PMID: 31252940 DOI: 10.1364/oe.27.017274] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 05/16/2019] [Indexed: 06/09/2023]
Abstract
The function of electrowetting liquid lenses is expanding beyond tunable focal length lensing. Recently, single and multi-mode oscillations on the meniscus profile of two non-miscible liquids have been used for optical phase modulation and fast focal length sweeping. To achieve a user-defined phase modulation, a prediction model of oscillation patterns and amplitudes is needed. We present digital holographic interferometry (DHI) measurements of oscillation patterns and amplitudes on a 5.8mm aperture lens up to 160 Hz, including frequency responses from 26-100 Hz. We discuss using Bessel function and Legendre polynomial models for oscillations on a conical frustum shaped electrowetting lens.
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Zohrabi M, Lim WY, Cormack RH, Supekar OD, Bright VM, Gopinath JT. Lidar system with nonmechanical electrowetting-based wide-angle beam steering. OPTICS EXPRESS 2019; 27:4404-4415. [PMID: 30876059 PMCID: PMC6410924 DOI: 10.1364/oe.27.004404] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 05/27/2023]
Abstract
A light detection and ranging (lidar) system with ±90° of steering based on an adaptive electrowetting-based prism for nonmechanical beam steering has been demonstrated. Electrowetting-based prisms provide a transmissive, low power, and compact alternative to conventional adaptive optics as a nonmechanical beam scanner. The electrowetting prism has a steering range of ±7.8°. We demonstrate a method to amplify the scan angle to ±90° and perform a one-dimensional scan in a lidar system.
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Affiliation(s)
- Mo Zohrabi
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309,
USA
| | - Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado Boulder, Colorado 80309,
USA
| | - Robert H. Cormack
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309,
USA
| | - Omkar D. Supekar
- Department of Mechanical Engineering, University of Colorado Boulder, Colorado 80309,
USA
| | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado Boulder, Colorado 80309,
USA
| | - Juliet T. Gopinath
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309,
USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309,
USA
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Zhang J, Zheng L, Zhao X, Sun Y, Feng W, Yuan M. Corneal aberrations after small-incision lenticule extraction versus Q value-guided laser-assisted in situ keratomileusis. Medicine (Baltimore) 2019; 98:e14210. [PMID: 30702573 PMCID: PMC6380743 DOI: 10.1097/md.0000000000014210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Previous studies compared ocular aberration and visual quality after small-incision lenticule extraction (SMILE) and Q value-guided femtosecond laser-assisted in situ keratomileusis (Q-FS-LASIK), but anterior corneal surface aberration properties are poorly known. This study aimed to compare the changes in anterior corneal surface aberration after SMILE versus Q-FS-LASIK.This was a prospective, observational cohort study. Patients with myopia and myopic astigmatism underwent SMILE or Q-FS-LASIK at Hangzhou MSK Eye Hospital between January 2015 and November 2015. High order aberration (HOA), primary spherical aberration (PSA), primary coma aberration (PCA), primary vertical coma aberration (PVCA), and primary horizontal coma aberration (PHCA) were assessed using pre- and postoperative Sirius scanning.Both surgery were associated with significant increases in postoperative HOA, PSA, and PCA (both groups P < .01). In the SMILE group (n = 51), the variations in HOA, PSA, and PCA were no longer significant after postoperative week 2 (P > .05). In the Q-FS-LASIK group (n = 73), the variations in HOA and PCA were no longer significant after postoperative day 1 (P > .05). In the SMILE group, the 3-month changes in PCA were not correlated with spherical, spherical equivalent (SE), and spherical plus cylinder measurements. Cylinder measurements were not correlated with HOA, PSA, and PCA. In the Q-FS-LASIK group, the 3-month changes in PCA correlated with spherical, SE, and spherical plus cylinder measurements.Both SMILE and Q-FS-LASIK resulted in an increase in HOA, PSA, and PCA at postoperative day 1, but Q-FS-LASIK introduced lower HOA and showed better stability. Spherical measurement was related to PSA.
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Lim WY, Supekar OD, Zohrabi M, Gopinath JT, Bright VM. Liquid Combination with High Refractive Index Contrast and Fast Scanning Speeds for Electrowetting Adaptive Optics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:14511-14518. [PMID: 30411903 DOI: 10.1021/acs.langmuir.8b02849] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Electrowetting adaptive optical devices are versatile, with applications ranging from microscopy to remote sensing. The choice of liquids in these devices governs its tuning range, temporal response, and wavelength of operation. We characterized a liquid system, consisting of 1-phenyl-1-cyclohexene and deionized water, using both lens and prism devices. The liquids have a large contact angle tuning range, from 173 to 60°. Measured maximum scanning angle was realized at ±13.7° in a two-electrode prism, with simulation predictions of ±18.2°. The liquid's switching time to reach 90° contact angle from rest, in a 4 mm diameter device, was measured at 100 ms. Steady-state scanning with a two-electrode prism showed linear and consistent scan angles of ±4.8° for a 20 V differential between the two electrodes, whereas beam scanning using the liquid system achieved ±1.74° at 500 Hz for a voltage differential of 80 V.
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