Enhancing the virtual reality optical efficiency via emission cone optimization of the display panel

The pancake lens, also referred to as a polarization-based catadioptric lens, is commonly employed as the imaging lens in virtual reality (VR) headsets due to its compact design and superior image quality. However, the pancake lens significantly reduces the optical efficiency to about 12.5% if the incident light is unpolarized, primarily due to the use of a half-mirror. To boost system efficiency, we analyze how the display panel's emission cone affects optical efficiency. By incorporating brightness enhancement films (BEFs) to tailor the angular distribution of the emitted light, the optical efficiency can be improved by 65.2%.