Abstract
Purpose: :
To develop continuously variable powered spherical and cylindrical lenses for the correction of refractive error.
Methods: :
Adjustable power lenses have been developed. The lenses are fabricated mounting a glass plate and a flexible membrane made of polydimethylsioloxane (PDMS) into an aluminum holder. The space between the membrane and the glass plate is filled with deionized water and the power of the lenses can be continuous varied by adjusting the volume of fluid within the lens. Both positive and negative powers are acheivable by increasing or decreasing the fluid volume from a baseline value. Furthermore, both spherical and cylindrical lenses can be fabricated using this method by changing the shape of the aperture in the aluminum holder. The radii of curvature of the deformed membrane was measured with interferometry to determine the change in lens power as a function of fluid volume.
Results: :
Spherical powers from -2.50 to 2.50 D in 0.2 D steps were achieve with our prototype. The change in power as a function of fluid volume is highly linear (r^2=0.99). Cylindrical powers from -3 diopters to +3 diopters were similarly achieved and have the same linear response. There is some induction of cylindrical power in the orthogonal direction with these lenses. The rate of induction was 0.17 D in the orthogonal direction for every 1 D in the desired direction. Higher order aberrations with these lenses remained small.
Conclusions: :
Fluidic lenses have the potential to create variable levels od spherical and cylindrical power. We envision a series of three lenses being used in a refractometer. The device would consist of a spherical lens and two cylindrical lenses rotated 45 degrees to one another. In this configuration and wide range of sphero-cylindrical corrections could be achieved, including cylinder axis variations.
Keywords: optical properties • refraction • astigmatism