OPTICAL SYSTEM, ILLUMINATION SYSTEM, DISPLAY SYSTEM, AND MOVING VEHICLE

An optical system includes a light guide member and a prism. The light guide member has: an incident surface on which light is incident; and a first surface and a second surface facing each other. The second surface is a light emergent surface. The prism is provided for the first surface and reflects, toward the second surface, the light passing inside the light guide member. The light guide member includes a direct optical path, along which the light that has entered the light guide member through the incident surface is directly reflected from the prism and allowed to emerge from the second surface.