New advancements in charged-coupled device (CCD) technology allow for further investigation into the spatial nature of night vision goggle (NVG) noise distributions. This is significant because it is common practice in new NVG technology to combine image intensifiers with CCDs for night vision imaging. In this study, images of NVG noise are recorded by a CCD camera while varying input radiance and using multiple goggle types. Noise distributions characterized using histograms of these images are analyzed and fitted with curves. Using the changes in the distribution and relating distribution changes (coefficient changes) to input radiance and goggle performance provides a very accurate noise characterization. This study finds that a Weibull distribution seems more appropriate than a Poisson distribution, producing higher correlation coefficient fits. In addition, the paper suggests possible ways the noise models developed here can impact advancements in NVG image enhancement using this new technology.
Anecdotal evidence suggested that bright, night-vision imaging system (NVIS) compatible, green cockpit displays could cause a veiling luminance in night-vision goggles (NVGs) and degrade visual performance. The mechanism suspected of causing this veiling luminance was an infrared emission from the image intensifier tube photocathode stimulated by visible, NVIS compatible light. This paper describes an effort to measure this stimulated infrared emission from three different image intensifier tubes. Measurements of the emission were analyzed with respect to tube age, the wavelength of incident illumination, and illumination angle of incidence. The emission was found during certain combinations of light wavelengths, angles, and intensities. However, results suggest that this phenomenon is not sufficiently strong to cause observable veiling luminance in NVGs.