Open AccessLarge aperture tunable-focus liquid lens using shape memory alloy spring
Author(s) -
Nazmul Hasan,
Hanseup Kim,
Carlos H. Mastrangelo
Publication year - 2016
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.013334
Subject(s) - optics , materials science , focal length , lens (geology) , shape memory alloy , radius of curvature , aperture (computer memory) , curvature , wavefront , dioptre , optical power , numerical aperture , actuator , optoelectronics , wavelength , physics , composite material , acoustics , laser , mean curvature , geometry , mathematics , visual acuity , mean curvature flow , electrical engineering , engineering
A tunable-focus large aperture liquid lens is constructed using shape memory alloy (SMA) springs as actuators. The lens mainly consists of a shallow liquid-filled cylindrical cavity bound by a thin compressible annular rim and encapsulated by a flexible circular membrane on the top of the rim and a rigid circular plate at the rim bottom. The lens optical power is adjusted by a controlled compression of the annular rim via actuation of the three shape-memory alloy (SMA) springs. Since the volume of the cavity liquid is constant, the rim compression bulges the flexible membrane outward thus reducing its radius of curvature and the lens focal length. The fabricated tunable lens demonstrated an optical power range of 0-4 diopters utilizing a driving voltage less than 3V. Lens optical wavefront profiling was done using a Shack-Hartmann sensor displaying a RMS wave front error of 0.77 µm and 1.68 µm at 0 D and + 4 D. The aperture diameter and thickness of the fabricated lens are 34 mm and 9 mm, respectively, while weighing 16.7 g.