Single-term theory of induced secondary axial color

Many optical systems require correction of secondary axial color. Although this is usually accomplished using materials with anomalous partial dispersion, it is also possible to correct secondary axial color using induced aberrations. Equations to calculate induced secondary axial color have been established previously but are difficult to understand and use in optical system analysis due to their complexity. By attributing secondary axial color contributions to spaces between surfaces instead of the surfaces themselves, we have developed a single sum that fully describes the induced secondary axial color of an optical system with thick lenses. This allows the source and magnitude of induced secondary axial color to be more easily understood.