Folding optical system with large field angle

The invention discloses a folding optical system with a large field angle, and relates to the technical field of optical imaging. The invention discloses a folding optical system with a large field angle. The folding optical system comprises a four-fold-back type folding optical system and a two-fold-back type folding optical system, each of the four-fold-back type folding optical system and the two-fold-back type folding optical system comprises a first metasurface, a second metasurface and a third metasurface; in the four-fold-back type folding optical system, a first metasurface, a second metasurface and a third metasurface are coaxially arranged with a substrate; in the secondary turn-back type folding optical system, a first metasurface and a third metasurface are coaxially arranged on a substrate, and a second metasurface is coaxially arranged on the front side of the third metasurface. According to the folding optical system with the large field angle, the field angle is larger than or equal to 40 degr