Hybrid lens design for ultrawide-angle imaging with a high Strehl ratio in a folded system.

When UV-curable material is used with a spherical glass lens, it is classified as a hybrid lens and can provide a new degree of freedom in designing a lens system. This method is used to explore the optical limitation of an ultrawide-angle imaging system of a folded structure, which is utilized to achieve a compact volume. The f-number and field of view of the system are 2.0 and 190°, respectively. Diffraction-limited performance is achieved within a field of view of 80° with Strehl ratios greater than approximately 80%. Even at the maximum field of view of 190°, the Strehl ratio is nearly 75%. The lens configuration is NNPNN, where N and P denote negative and positive optical power, respectively; this configuration uses only two aspherical hybrid lens surfaces. Comparisons of different optimizations are also provided.