U.S. Navy research on extremely low-light (ELL) cameras in nighttime underwater operations is limited. This study aims to address this limitation in capability by quantifying the Teledyne Bowtech Limited Explorer Pro Low Light Monochrome Camera’s performance in the field as a function of water depth at night in the coastal ocean. To reach this goal, proven techniques like modulation transfer function (MTF) and contrast transfer function (CTF) analyses were applied to modified target patterns for lower-quality images. The new target pattern was tested on land using commercial cameras against a commercial test pattern chart for high-resolution cameras. The ELL camera vertical casts, including measures of surface lux and the water column characteristics, were performed at California’s Monterey Harbor and Bay in the presence of bioluminescence. The MTF results from the target pattern showed a steady MTF as the spatial frequency increased; the MTF decayed with increasing depth and decreasing lux. Furthermore, the MTFs showed that bioluminescence improves the MTF at depths > 24.5 m versus the MTF with no bioluminescence. The target pattern was detected at a maximum depth of 37 m. However, predicted maximum depths using a linear regression model were > 37 m with and without bioluminescence. The new ideal target pattern for the ELL video camera provides a foundation for nighttime underwater operations and the future development of underwater night vision goggles for the U.S. Navy.Office of Naval Research (Arlington, VA 22203-1995)Lieutenant Commander, United States NavyApproved for public release. Distribution is unlimited
