Analysis and application of refractive variable-focus lenses in optical microscopy

Abstract

We present an approach to an analysis of the third order monochromatic and chromatic aberrations of refractive fluid lenses with a variable focal length. A detailed theoretical analysis is performed for a simple variable-focus lens and formulas are derived for an optical design of such lenses. The advantage of these active lenses is their capability to change continuously the focal length within a certain range. These lenses give a possibility to design non-conventional optical systems which change their parameters (focal length, magnification, etc.) in a continuous way without a need for mechanical movements of lenses. Such lenses with a variable focal length make possible to design optical systems with functions that are difficult or even impossible to combine using conventional approaches. We perform an analysis of optical design of such lenses. The experimental analysis and calculations are provided for Varioptic lens Arctic-416. Potential applications of variable-focus liquid lenses in optical microscopy are analyzed and simulated. We also investigate a possibility of increasing the depth of focus using such lenses and the influence of a variable-focus lens on the image quality.