MIL-DTL-43511D
760
760
∑T*V
∑T*V
λ′
λ
9.496
8.603
Tphotopic =
=
= 88.87
Ts cot opic =
=
= 88.63
λ=380
λ=380
760
760
∑V
∑V
10.686
9.707
λ′
λ
λ=380
λ=380
1/ V(λ) = the photopic relative luminous efficiency (CIE 1924 Standard)
2/ V(λ′) = the scotopic relative luminosity (CIE 1925 Standard)
3/ T = transmittance of the sample under test (here a Class 1 sample)
4/ T/photopic = Percent photopic transmittance
5/ T/scotopic = Percent scotopic transmittance
4.4.4 Optical density of class 3 test. The optical density of the class 3 visors shall be calculated
by first determining the luminous transmittance in accordance with ASTM D 1003. The optical
density shall be calculated by the formula:
1
Optical Density = Log Transmittance
4.4.5 Optical distortion of critical areas test. The optical distortion of the critical area of the
visors shall be determined by inserting the visor with its surface normal to the line of sight into
the apparatus described on figure 4. The degree of off-parallelism shall constitute the amount of
distortion. The visor shall be compared with the plates on figure 2.
4.4.6 Haze test. The haze shall be determined in accordance with ASTM D 1003.
4.4.7 Ultraviolet transmittance test. The erythemal ultraviolet transmittance shall be measured
by a spectrophotometer.
4.4.8 Neutrality of class 2 and 3 visors test. The spectral transmittance of the class 2 or 3 visor,
as applicable, shall be measured by a spectrophotometer having a monochromator band width of
10 nm or less and a reproduction of plus or minus 1 percent. The neutrality shall be calculated
by the Judd Daylight Duplication Method. Table IV shows an example for the calculation of
spectral transmittance deviations.
TABLE IV. Example for calculation of spectral transmittance deviation. 1/ 2/ 3/ 4/ 5/
Average
Wave
Wave
Trans-
Percent
length
Band
length
mittance
deviation
(nm)
T
N
range
Tn
100(1-Tn/Tc) x Weight = Product
430
0.114
440
0.118
450
0.127
460
0.137
1
430-490
0.133
14.25
5
71.2
470
0.142
480
0.144
490
0.145
2
460-520
0.145
6.34
10
63.4
500
0.147
510
0.149
520
0.151
3
490-550
0.151
2.80
10
28.0
530
0.153
540
0.154
10
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