White Paper: Test & Measurement
NVIS Measurement of Displays and Panel Graphics
For NVIS measurements, it is critical that the extremely high-intensity differences between the visible and near infrared spectral ranges are measured correctly (typically 380 to 930 nm). This applies to large displays, small switches, and symbol measurement according to e.g. MIL-STD-3009, MIL-L-85762A, MIL-DTL-7788G (former MIL-P-7788F), JSSG-2010-5, ARP 5825, RAE WP 6, and others. The NVIS display test system DTS 140D NVIS combines the advantages of the high-end array spectroradiometer CAS 140D (with further stray light suppression and automatic adjustment of measurement sensitivity) and the telescopic optical probe TOP 200 with built-in viewer camera. The TOP 200 guarantees a perfectly round and sharp measuring spot with an optimized Pritchard style optical system (with spot diameter from 75 micron up to inches).
The use of this test system solves the complexity of NVIS radiance measurements: 1. The spectral response functions rendered by the image intensifier, which is used in night vision goggles, has the following characteristics (NVIS A/B/C): Optical radiation in the spectral range from approximately 650 to 930 nm is amplified by five orders of magnitude and converted to visible light. Thus, the radiance of the display in that spectral region must be extremely low compared to the visible spectrum in order to avoid blinding/shutter. 2. The NVIS radiance readings have to be scaled to the luminance of the same sample.
The CAS 140D meets all requirements for radiance and color accuracy that acquire the radiation spectrum from 380 to 930 nm. Luminance and NVIS radiance are calculated from the spectroradiometric data, enabling proper weighting and scaling. Different integration functions can easily be implemented by the user in the software (e.g. future goggle response curves or other standards). The article reviews the features of the NVIS display test system and discusses its measurement performance in specific applications.
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