One of the challenges high-speed digital camera manufacturers face is a limited dynamic range. The dynamic range of a digital camera is the ratio of light captured by the pixel to the noise floor (composed of camera read noise, shot noise, and dark current noise) of the camera. High-speed cameras must have high sensor gains, large fill factors, and large pixels to account for the very short exposure times required in high-speed videography otherwise they succumb to noise limitations. The high-speed operational requirements limit the total dynamic range that most high-speed digital cameras can operate within, typically close to 60 dB, or about 10 stops.
Breaking through the above restrictions, Navy researchers have developed a cascade imaging system with commercially available parts to capture full scene radiance information and video. The system has been demonstrated to capture a scene in excess of 160 dB or 27-stops dynamic range, limited only by the parts that were readily available. Specifically for a high dynamic range (HDR) image, the light beam from a scene is divided by beam-splitters and attenuated by neutral density filters. After acquisition by separate cameras, the radiant exitance from each beam division is combined from which to estimate original scene exitance. Weighting functions are employed to minimize symmetrical errors. The final HDR image is constructed from the weighting averages of the original scene exitance.
This method has been used to capture explosive detonations without the typical oversaturation that occur in close proximity to flash as well as the optical enhancement of events occurring in low-light surroundings. This process can view several different phenomena from a rail gun launch, welding, flashbang grenade detonation, 6-inch gun muzzle blast at 25,000 frames per second (fps), and the burning of a flashbulb at over 10,000 fps spanning over 150 dB dynamic range.
- Method has been used to capture dynamic events without the typical over saturation that occurs in close proximity to explosive events as well as the optical enhancement of events occurring in low light surroundings
- System can be used to develop a single camera with a single lens and multiple imagers, or use multiple commercial-off-the-shelf standalone systems
- Setup and the tone mapping of the series of images provide an authentic looking final image correct for viewing on modern low dynamic range media
- Businesses can acquire the technology by licensing US patent 9,998,692
- Potential for collaboration with Navy scientists and engineers
- License fees are negotiable
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