OPTICAL SYSTEM, VIRTUAL IMAGE DISPLAY DEVICE, AND HEAD-MOUNTED DISPLAY

An optical system includes a light guide (30), a partial reflector (320), and a polarizer (70). The light guide (30) has a light-emission surface (340); and an outer surface (350) opposite to the light-emission surface (340). The polarizer (70) on the outer surface (350) transmits a part of incident light incident on the polarizer (70). The polarizer (70) has a first transmittance in a first polarization direction higher than a second transmittance in a second polarization direction orthogonal to the first polarization direction, with respect to vertical incident light incident perpendicularly on the polarizer. The partial reflector (320) has a first reflectance in the first polarization direction lower than a second reflectance in the second polarization direction, with respect to the vertical incident light.