Optical film

An optical film comprising, in sequence from a light entry side of the optical film to a light emission side of the optical film:

• a plurality of first prisms;
• a first phase-difference plate;
• and
• a polarized-light separating element,
• the plurality of first prisms each having (i) a first surface through which light enters the first prism and (ii) a second surface that reflects the light, having entered the first prism through the first surface, toward the light emission side,
• the optical film further comprising, between the plurality of first prisms in an in-plane direction of the optical film, a light reflecting section that reflects light, having been reflected by the polarized-light separating element toward the light entry side, back toward the light emission side;
• wherein
• the light reflecting section is a second prism having a third surface and a fourth surface each of which reflects light;
• two passages through the first phase-difference plate, total reflection at the third surface, and total reflection at the fourth surface cause a phase shift in a total amount of 2π;
• the first phase-difference plate has a slow axis that is parallel to a direction in which the second prism extends;
• and
• the polarized-light separating element has a polarized-light transmission axis that is angled at 45 degrees with respect to the direction in which the second prism extends.