Selection of liquid parameters for chromaticity correction in liquid lenses

Subject of study . The parameters of liquids forming a liquid doublet lens with a variable focal length are investigated. Aim of study . The aim was to establish the relationship between the Abbe dispersion coefficients ( ν D ) and the refractive indices ( n D ) of the liquids composing a liquid lens that enables an achromatic correction for position chromaticism (Δ s ′ ). Method . Liquid doublets with various n D and ν D values were simulated, and their influence on the changes in position chromaticism (Δ s ′ ) and magnification chromaticism (Δ y ′ ) was examined. Main results . We determined the conditions for selecting combinations of optical liquids in which an n D value corresponded to a high ν D value, and accordingly, a low n D value was associated with a low ν D value. We achieved an achromatic type of correction for Δ s ′ when its values at two points were equal to zero. The results show that the difference in the Abbe dispersion coefficients of the liquids should not exceed 10–15 units. In addition, the difference in their refractive indices should have the maximum possible value; this maximum difference is required to provide a large membrane curvature radius and thus reduce the monochromatic aberrations of the liquid doublet while increasing its relative aperture. Practical significance . The results obtained by evaluating the properties of the liquids forming a doublet provide insights for designing liquid components with an achromatic type of correction for Δ s ′ ; such liquid doublets can be used both as independent lenses in telescopic systems and as components of more complex optical devices.