Source — Filters can be quantified with any reference source. Wamco supplies filter data with the actual source specified by your application. You get the assurance that the filter will meet your specifications.
Chromaticity — Color is controlled in terms of u', v', and r. In the case of incandescent filters, color varies as a function of Kelvin. Wamco filters are designed to provide a minimum color shift as Kelvin varies. For other sources, color is controlled by using the measured spectral energy of the actual application source.
Photopic transmission (Y%) — Y% is a direct indication of the "brightness" of the filtered display as seen by the unaided eye. Using a photometer, Y% can be calculated by dividing the filtered display luminance by the unfiltered display luminance. The peak transmission of the filter does not provide the same information.
NVIS performance — The Class-A (rotary wing) NVIS Radiance (NRa) and Class-B (fixed wing) NVIS Radiance (NRb) values are given at the MIL-L-85762A specified luminance levels. Wamco filters are offered with a much lower NR than the maximum allowable, to provide a "safety factor" for design and measurement. In addition, data for other NVIS performance indices is available.
T2B — The Illuminant B double pass transmittance (T2B) is an indicator of contrast used to determine daylight readability of filtered displays. T2B is defined as the transmittance resulting from a spectral energy distribution simulating sunlight (Illuminant B) that passes through the filter, reflects off a 100% reflectance standard, and transmits back through the filter. T2B should be minimized with respect to Y% for applications that require daylight readability. In general, if two filters have roughly identical Y%, the filter with the lower T2B will have higher contrast.
For more information or help in finding an NVIS lighting solution, please contact us.
