Variable Attenuator for See-Through Day/Night Displays

Degraded visual environments refer to any ambient condition that reduces the pilot’s or Soldier’s ability to see information that is necessary to maintain situational awareness. One way the Army mitigates this is by providing synthetic symbology and imagery. Although symbology requires one shade of gray above background, imagery requires one v2 increase in luminance for every shade of grey. Often, there is not enough luminance that the display can emit in high ambient environments for the pilot (or Soldier) to see the gray shade detail of the imagery. In addition, high ambient light can dramatically reduce the ability to differentiate color, which is detrimental when symbology is color-coded. To mitigate this issue, SA Photonics has developed an electrically controllable variable attenuator system. This system can also be used in a mode that eliminates light from propagating downrange at night, a problem with current augmented reality systems. Our light-secure variable attenuator system (LVAS) uses a high speed attenuator and, when in light secure mode, pulses the microdisplay so that it is only on while the electronic attenuator is dark (in normal mode the display is always on). Light secure mode provides both see-through and the elimination of forward propagating light.