MIL-PRF-38169A
or goggle lens. The color of the lens shall be essentially neutral; consequently, no spike between
380 and 770 nm shall exceed 5.0% transmittance.
3.3.7 Erythemal ultraviolet transmittance of class 1 and class 2 visor and goggle lens. The
erythemal ultraviolet transmittance of class 1 and class 2 visor and goggle lens shall be less than
5%.
3.3.8 Neutrality of class 2 visor and goggle lens. The spectral transmittance of the class 2 visor
and goggle lens may vary with wave lengths between 380 and 770 nm, but the average spectral
transmittance deviation percentage within nine spectral bands shall be less than 12 (see 6.3.3).
3.3.9 Spectral transmittance.
3.3.9.1 Class 1 visor and goggle lens. The spectral transmittance of the class 1 visor and goggle
lens shall not be less than 90% throughout the critical areas. The spectral transmittance in the
noncritical areas shall be within 25% of the spectral transmittance in the critical areas.
3.3.9.2 Class 2 visor and goggle lens. The spectral transmittance of the class 2 visor and goggle
lens shall not exceed 15% ± 5% when measured at point C. The transmittance of point C for the
left eye and point C for the right eye of the same visor and goggle lens shall not differ by more
than 20%. The total visible transmittance at the top of the visor and goggle lens shall not exceed
the total visible transmittance at the bottom of the visor and goggle lens.
3.3.10 Chromaticity of class 2 visor and goggle lens. The chromaticity coordinates x and y of the
class 2 visor and goggle lens shall be within the limits indicated in figure 2.
3.3.11 Colorfastness to light of class 3 visor and goggle lens. After the class 3 visor and goggle
lens are subjected to the colorfastness test, the average spectral transmittance of the class 3 visor
and goggle lens in the range between 380 and 770 nm shall be 2% (± 0.5%). There shall be no
evidence of peeling, warping, cracking, crazing, optical distortion of the critical area, or any other
optical defects.
3.3.12 Resistance to thermal shock of class 3 visor and goggle lens. After the class 3 visor and
goggle lens has been subjected to the thermal shock test, the average spectral transmittance of the
class 3 visor and goggle lens in the range between 380 and 770 nm shall be 2% (± 0.5%). There
shall be no evidence of peeling, warping, cracking, crazing, optical distortion of the critical areas,
or any other optical defects.
3.3.13 Durability of coatings for class 3 visor and goggle lens.
3.3.13.1 Adhesion of metallic film. If coatings are incorporated on either surface, the metallic
film shall not dislodge, pull away, or tear.
3.3.13.2 Abrasion resistance. If coatings are incorporated on either surface, there shall be no
visible abrasion of, or removal of, the coating during testing.
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