Refractive index measurement system for contact lens in a natural hydrated state

Todd Szarlan; Donald Gibson; Travis King; Filipp Ignatovich

doi:10.1117/12.2526093

28 February 2019 Refractive index measurement system for contact lens in a natural hydrated state

Todd Szarlan, Donald Gibson, Travis King, Filipp Ignatovich

Proceedings Volume 10858, Ophthalmic Technologies XXIX; 108582D (2019) https://doi.org/10.1117/12.2526093
Event: SPIE BiOS, 2019, San Francisco, California, United States

Abstract

Accurate refractive index of the contact lenses is one of the most important parameters needed to properly evaluate the lens performance. Measurements of the refractive power and other optical properties of the lenses are typically conducted in solution and converted to in-air performance. Such an approach is very sensitive to errors in the refractive indices of both the lens and the solution.

A number of different approaches have been undertaken by the manufacturers to overcome this difficulty. Efforts to accurately measure the phase refractive index a contact lens directly have for the most part been unsuccessful due to a curved shape of the lens and lens material properties. In this paper we describe a different approach of obtaining a group index dispersion curve with high accuracy of 0.003 or better, and discuss practical implications.

We have conducted measurements of the group refractive index (GRI) of hydrogel contact lenses at different wavelengths, from 530 to 670 nm, using time-domain low-coherence interferometer (LCI), based on the super-continuum light source (SCLS). The technique is being developed to overcome sources of error in the current measurement technique.

Citation Download Citation

Todd Szarlan, Donald Gibson, Travis King, and Filipp Ignatovich "Refractive index measurement system for contact lens in a natural hydrated state", Proc. SPIE 10858, Ophthalmic Technologies XXIX, 108582D (28 February 2019); https://doi.org/10.1117/12.2526093

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