US Patent 7170057 Image enhancement system and method for night goggles

A dichroic type narrow-band-pass filter is used as a beamsplitter inside a night vision goggle eyepiece. The filter is combined with appropriately aligned polarizers and liquid crystal type shutter rotators movable between a “P” orientation and an “S” orientation to transmit center band and side band wavelengths of the normal view or night scene for recording, transmitting or enhancing. In the enhanced low light level mode, the intensified visible image presented to the user comprises a 40 degree circular image with a 30 degree by 22.5 degree rectangular display insert.