Abstract

The accurate and repeatable rendering of images in display systems designed to produce realistic training with stimulated Night Vision Goggles (NVGs) assumes we know what light  levels we are trying to achieve and that we have some practical means of measuring the levels produced.  In the first part of this paper we provide our best current estimate of the real world levels of lunar luminance and radiance, paying particular attention to the balance between the energy in the visible and the pass band of NVGs.

In the second part of the paper we review four distinct methods of determining the level of class-B NVIS radiance (NR_b) in a training display system.  We describe in more detail the spectrometer-based approach we recommend and provide examples of the three basic measurements we assert are the minimum set of measurements needed to characterize the ability of a display system to accurately stimulate NVGs.  These measurements are the ratio of NR_b to luminance (NR_b/Lum), the contrast ratio in the NVG pass band (CR_NRb), and the level of NR_b for the peak white of the display system (NR_bW).

In the final section of the paper we provide a worked example of the proposed measurements and calculations for a simple display system incorporating an LCoS projector.