US Patent 11933949 Freeform folded optical system

A freeform folded optical system that include two freeform prisms with optical power. At least one of the freeform prisms is configured to fold the optical axis twice. Thus, embodiments of the freeform folded optical system fold the optical axis three or four times. Folding the optical axis three or four times in the freeform prisms allows for long focal lengths required for telephoto lens applications without requiring additional lens elements between the prisms. In addition, the configuration of the freeform folded optical system provides reduced Z-axis height when compared to conventional folded lens systems with similar optical characteristics.