Backlight and display system

A display system comprising:

• a plurality of discrete spaced apart light sources arranged two-dimensionally on an optically reflective surface;
• a display panel disposed on the light sources and configured to form an image;
• a reflective polarizer disposed between the display panel and the light sources;
• and
• an optical film disposed between, and substantially co-extensive in length and width with, the reflective polarizer and the light sources, each of the reflective polarizer and the optical film comprising a plurality of polymeric layers numbering at least 10 in total, each of the polymeric layers having an average thickness of less than about 500 nm,
• such that for a substantially collimated incident light propagating in an incident plane, a visible wavelength range extending from about 420 nm to about 680 nm, and an infrared wavelength range extending from about 700 nm to about 780 nm:
• for a first incident angle of less than about 5 degrees and the visible wavelength range, the plurality of polymeric layers of the reflective polarizer has an average optical reflectance of at least 60% when the incident light is p-polarized and an average optical transmittance of at least 60% when the incident light is s-polarized;
• for the first incident angle and for the average of p-polarized and s-polarized incident lights, the plurality of polymeric layers of the optical film has an optical transmittance T1a at at least one visible wavelength in the visible wavelength range and an optical transmittance T1b at at least one infrared wavelength in the infrared wavelength range;
• for a second incident angle of greater than about 35 degrees and for the average of p-polarized and s-polarized incident lights, the plurality of polymeric layers of the optical film has an optical transmittance T1c at the at least one visible wavelength and an optical transmittance T1d at the at least one infrared wavelength, T1a/T1c≥1.5, T1b/T1d≤0.7.