Abstract: An eyepiece optical system and a head-mounted display are disclosed. The optical system comprises a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged coaxially and successively along an optical axis direction from an eye viewing side to a displayer side, wherein a focal length of the second lens is f2, a focal length of a lens group formed by the third lens and the fourth lens is f34, a focal length of the fifth lens is f5, a distance from a display of the optical system to the fifth lens proximate to a surface of the display is fd, and a total system length is fw. When a particular relation is satisfied, on the basis of cost reduction and weight reduction, significant elimination of system aberration as well as high-quality optical indices can be achieved.

Abstract: The present invention relates to an eyepiece optical system and device with a large field-of-view angle and high image quality, comprising a first lens group and a second lens group arranged successively along an optical axis from a human eye observing side to a micro display. The first lens group is composed of one or more lenses, and the second lens group comprises a Fresnel lens. The Fresnel lens comprises a Fresnel surface. By the use of a combination of a novel optical surface shape, i.e., the Fresnel surface shape, and traditional optical spherical and aspherical surface shapes, when focal lengths of various lenses and lens groups meet particular conditions, significant elimination of system aberration, reduction of the sensitivity of various optical components, and easy processing and assembly of the components can be achieved.