| NVIS Radiance |
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To be NVIS compatible, an illuminated display should emit a minimum of radiation within the response range of the NVIS and should not cause any degradation of the NVIS image.
NVIS radiance (NR) is a figure of merit defined by MIL-L-85762A to measure the degree of NVIS interference of a display at a specified luminance. As a figure of merit, NR can be used to compare the relative NVIS compatibility of displays.
NR is calculated from the measured spectral radiance of a display. The spectral radiance curve of a typical filtered incandescent green display is shown in figure 11a. The NR calculation can be broken down into two steps.
Step 1
Compute the overlap radiance (R). R is the area under the curve obtained by multiplying the display radiance (figure 11a) and the NVIS response function (figure 11b). The resulting curve is shown in figure 11c.
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| Figure 11a: Spectral response of an NVIS-compatible display. |
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Figure 11b: NVIS (Class A) photoresponse. |
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Figure 11c: Product of display spectral radiance and NVIS response curves (overlap radiance). |
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