Large area infrared sensor film

A display system for imaging a user body portion placed proximate to the display system, the display system comprising:

• a display panel configured to generate an image for viewing by the user;
• an optical sensor disposed on the display panel opposite the user body portion and configured to detect light having at least a first wavelength and reflected by the user body portion, optically active regions of the optical sensor and the display panel substantially co-extensive with each other in length and width;
• and
• an optical stack disposed between the display panel and the optical sensor and comprising:
• a first optical reflector facing the display panel and comprising a plurality of first polymeric layers numbering at least 30 in total, each of the first polymeric layers having an average thickness of less than about 500 nm;
• and
• a light collimating film facing the optical sensor and comprising a plurality of substantially coplanar alternating first and second regions, each of the first regions having a lateral maximum dimension W1 and a height H1, H1/W1≥2, such that for an incident light, a visible wavelength range extending from about 420 nm to about 680 nm, and an infrared wavelength range extending from about 750 to about 1500 nm and comprising the at least the first wavelength:
• for each of a first incident angle of less than about 5 degrees and a second incident angle of between about 40 degrees and about 70 degrees, the plurality of polymeric layers has an average optical reflectance of greater than about 70% in the visible wavelength range and an optical transmittance of greater than about 30% for the at least the first wavelength in the infrared wavelength range;
• for the first incident angle and each of the visible and infrared wavelength ranges, the first regions of the light collimating film have an average optical transmittance of greater than about 50%, and the second regions of the light collimating film have an average optical absorbance of greater than about 30%;
• and
• for the second incident angle and each of the visible and infrared wavelength ranges, the optical stack has an optical transmittance of less than about 10%.