Design of annular folded lenses using freeform gradient-index optics

Annular folded lenses (AFLs) offer high resolution monochromatic imaging in a low telephoto ratio package. Monolithic designs offer advantages but are inflicted with chromatic aberrations. Applying freeform gradient- index media enables more advanced, diffraction-limited monochromatic AFL designs. By optimizing the GRIN profile along with its dispersion, chromatic aberrations can also be corrected, granting high performing poly- chromatic designs.