abstract
- © 2020 Elsevier B.V.We present the exact equations to design a stigmatic singlet that meets the Herschel's condition. We determine analytically how must be the first and second refractive surface of the lens such that the singlet is stigmatic and meets Herschel's condition. To achieve this, we numerically solve a nonlinear differential equation. We show several illustrative examples of these new family lenses, and also we discuss their limitations.