Optical film for oxygen saturation sensing

A display system for sensing a user body portion placed at or proximate to the display system, the display system comprising:

• a display panel configured to form an image for viewing by the user;
• an optical reflector comprising a plurality of polymeric layers numbering at least 50 in total, each of the polymeric layers having an average thickness of less than about 500 nm;
• and
• at least one optical sensor configured to sense a visible light having at least one visible wavelength in a visible wavelength range extending from about 420 nm to about 680 nm and an infrared light having at least one infrared wavelength in an infrared wavelength range extending from about 750 to about 1500 nm, the at least one optical sensor sensing the visible and infrared lights after the visible and infrared lights are transmitted by the optical reflector;
• such that for a substantially normally incident light, the plurality of polymeric layers of the optical reflector has:
• an average optical reflectance of greater than about 80% in the visible wavelength range;
• an optical transmittance of greater than about 50% at the at least one infrared wavelength;
• an optical transmittance of greater than about 2% and less than about 10% at the at least one visible wavelength;
• and
• an optical transmittance versus wavelength that comprises a bandpass segment comprising a full width at half maximum (FWHM) that comprises the at least one visible wavelength.