A head-mounted display (HMD) comprises a frame for hanging on a user's head, and a display device affixed to the frame. The display device comprises alight source, a driving circuit for generating data signals, a polarization beam splitter (PBS), for passing the light emitted from the light source, a liquid crystal on silicon panel (LCOS panel) for reflecting the light from the PBS based on the data signal generated by the driving circuit, and a lens group including a biconvex glass spherical prism and an aspherical plastic prism. The lens group is used for focusing the reflected light from the LCOS panel.