Panamorph’s multi-patented Projection BackLighting (PBL) technology concentrates the light going through the LCD display in a VR headset into a much smaller angle than can be achieved with traditional diffusion-based LCD backlights and even emissive displays. This results in also concentrating the light passing through a pancake lens magnifier to just the user’s eye region rather than the surrounding area, providing over 65% power savings while also decreasing cooling requirements. Most importantly, the subsequent decrease in scattered light through the pancake lens substantially increases the visual contrast through the system versus traditional backlighting approaches.

PBL is very simply implemented by use of an off-axis, concave mirror arrangement to project the light from an off-axis LED array though multiple reflections and polarization manipulations, then through the LCD panel as the aperture stop of the lighting system and then to form an image of the LED array at the optical system exit pupil, resulting in a compact arrangement averaging less than 9mm of depth behind the LCD panel for a panel of 56mm diameter. 

We are proud to be presenting our paper on optical arrangements and benefits of PBL at the Society for Photo-optical Instrumentation Engineers (SPIE) conference on Monday,  January 27 in San Francisco (8:20 – 8:40 am, Room 3008 of Moscone Center West). We will also be demonstrating PBL in a binocular arrangement in Booth 6436 in the exhibition hall on that Tuesday and Wednesday.

PBL is available for immediate implementation by licensed partners for next generation headsets. However, this simple implementation represents just the beginning of a longer term development roadmap. In summary, PBL allows the display system exit pupil to be an image of the LED lighting array. Consequently, turning on only those LEDs responsible for light going through the user’s eye as a result of eye-tracking means even more scattered light can be reduced for even greater contrast. Further, by only constraining that light into a bundle smaller than the user’s eye pupil, Maxwellian optical properties are introduced for higher clarity and greater depth of focus to reduce vergence-accommodation conflict.

For further information and to see an advance draft of the SPIE paper please email Shawn Kelly.