MIL-DTL-62422D(AT)
4.5.5 Photopic transmission (PT). To determine conformance to 3.5.2, one of the
following systems shall be utilized:
a. A constant current tungsten lamp, a monochromater, and a detector.
b. A double beam spectrophotometer.
c. A photometer.
The system shall be traceable to the National Institute of Standards and Technology through a
calibrated neutral density filter(s).
4.5.5.1 Photopic transmission measurement. The preferred wavelength range for this
measurement is 380 nm to 760 nm. Any range that includes the range 400 nm to 700 nm is
acceptable. The filter shall be illuminated with a tungsten lamp with color temperature of
2854 degrees Kelvin (Illuminant A). Photopic transmission shall be derived from multiplying
measured spectral transmission readings taken every 10 nm or less by the photopic luminous
efficiency values that make up the standard human eye curve established by the Commission
Internationale del Eclair (CIE) (see ASTM D1003).
4.5.5.2 Photopic transmission derivation. To determine conformance to 3.5.2, the
photopic transmission (PT) shall be derived from:
760
760
Y S (w)V (w)dw
X T (w)S (w)V (w)dw
380
380
PT = X/Y
where,
w = wavelength
T(w) = Filter transmission characteristics
S(w) = CIE source A characteristics
V(w) = Photopic visibility function
dw = 10 nm or less intervals
4.5.6 Chromaticity. To determine conformance to 3.5.3, the chromaticity of the filter
shall be measured as specified in 4.5.6.2 using the apparatus specified in 4.5.6.1.
4.5.6.1 Chromaticity apparatus. The apparatus for measuring the chromaticity shall be
as specified in 4.5.5.
4.5.6.2 Chromaticity measurement. The filter shall be illuminated with a tungsten lamp
with a color temperature of 2854 degrees Kelvin (Illuminant A). The transmission of the filter
12
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business