Optical system and head mount display

An optical system, comprising:

• a first lens with a first surface and a second surface provided oppositely, comprising a light input-coupling end-face connected to the first surface and the second surface;
• a polarizing reflector provided on a side of the first lens distal to the light input-coupling end-face, light being incident into the first lens from the light input-coupling end-face and adapted to be reflected to the polarizing reflector via at least one of the first surface and the second surface;
• a beam splitter lens provided on a side where the second surface of the first lens is located;
• a second lens comprising a compensating lens, provided between the beam splitter lens and the first lens, and configured to compensate for focal power of the beam splitter lens;
• and
• a phase retarder provided on the beam splitter lens or on the second lens, comprising a body and an extension, the body being provided corresponding to a central region of the beam splitter lens, the extension adapted to extend from the body toward an outer edge of the beam splitter lens, and an outer edge of the extension being adapted to be aligned with the outer edge of the beam splitter lens.