8 September 1995 Image enhancement using a range-gated microchannel-plate image intensifier (MCPII) video system with a 180-ps FWHM shutter
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The video image of a target submerged in a scattering medium was improved through the use of range gating techniques. The target, an Air Force resolution chart, was submerged in 18 inch of a cloudy solution of tincture green soap and water. The target was illuminated with pulsed light from a Raman shifted, frequencfy-doubled, Nd:YAG laser having a wavelength of 559 nm and a width of 20 ps FWHM. The laser light scattered by the target and soap solution, along with the light reflected by the surface of the tank holding the water, was imaged onto a MCPII. The output from the MCPII was then recorded with a RS-170 video camera and a video digitizer. The MCPII was shuttered on with a pulse synchronously times to the laser pulse. The relative timing between the reflected or scattered laser pulse and the shuttering of the MCPII determined the distance to the imaged region. The resolution of the image was influenced by the MCPII's shutter time. A comparison was made between the resolution of the images with 6 ns, 500 ps and 180 ps FWHM (8 ns, 750 ps, and 250 ps off-to-off) shutter times. It was found that the image resolution increased with decreasing shutter time. The longer exposures allowed more light scattered by the water to be recorded along with the light from the target. The presence of this scattered light in the image increased the noise, thereby reducing the contrast and the resolution.
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Matthew C. Thomas, Matthew C. Thomas, George J. Yates, George J. Yates, Paul A. Zagarino, Paul A. Zagarino, } "Image enhancement using a range-gated microchannel-plate image intensifier (MCPII) video system with a 180-ps FWHM shutter", Proc. SPIE 2551, Photoelectronic Detectors, Cameras, and Systems, (8 September 1995); doi: 10.1117/12.218627; https://doi.org/10.1117/12.218627

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