Abstract: An optical film and a liquid crystal display are provided. The liquid crystal display includes a twisted nematic type liquid crystal panel and a backlight module. The liquid crystal panel includes a bottom polarizer, a liquid crystal cell, and a top polarizer. The liquid crystal cell is placed between the bottom polarizer and the top polarizer. The backlight includes a reflective polarizer and a half-wave plate, and the half-wave plate is placed on the reflective polarizer. The transmission axis of the bottom polarizer and the principle axis of the bottom polarizer differ a first angle. The transmission axis of the bottom polarizer and the reflective polarizer differ a second angle. The first angle is half of the second angle.

Abstract: An optical reflective film that includes pluralities of repeating units is provided. The repeating unit includes a first multiplayer-film unit and a second multiplayer-film unit. The first multiplayer-film unit and the second multiplayer-film unit are by stacking a first polymeric material A and a second polymeric material B. The first polymeric material A and the second polymeric material B differ from each other in refractive index by at least about 0.03. The stacking order in the first multiplayer-film unit is 1A:xB:1A, and the stacking order in the second multiplayer-film unit is 1B:yA:1B, where x and y represent the optical thickness multiple of the middle polymeric material relative to the neighboring polymeric material. X and y are not equal and have a proportional relationship to each other. For the visible light, the ratio of the first multiplayer-film unit and the second multiplayer-film unit in the effective refractive index is about 1.00.