MIL-PRF-29580C
3.4.2.4 Lens defects. When inspected as specified in 4.5.1.4, the spectacle lenses shall be
free from irregularities affecting optical qualities.
3.4.2.5 Lens fit. When inspected as specified in 4.5.1.5, the spectacles shall show no
evidence of visible space between the frame and lens.
3.4.2.6 Curvature. When measured as specified in 4.5.1.6, the curvature of the lenses shall
be not less than 5 diopters, nor greater than 15.5 diopters.
3.4.3 Spectral transmittance requirements.
3.4.3.1 Optical density and angular protection. When tested as specified in 4.5.2.1, the
spectacles shall have the required optical density and prevent passage of threat wavelengths or
laser radiation regardless of the threat incidence angle (see 6.2).
3.4.3.2 Transmittance. When computed as specified in 4.5.2.2, the scotopic transmittance
shall be not less than 20 percent. Photopic and scotopic transmittance shall not differ by more
than 10 percent of the measured value between lenses or over the surface of the lens.
3.4.3.3 Near-infrared transmittance. When computed as specified in 4.5.2.3, the average
near-infrared transmittance shall be less than 15 percent.
3.4.3.4 Erythermal ultraviolet transmittance. When computed as specified in 4.5.2.4, the
erythermal ultraviolet transmittance shall be not greater than 0.2 percent.
3.4.3.5 Haze. The haze value of the lenses shall be minimized and when determined as
specified in 4.5.2.5, shall be not greater than 4 percent.
3.4.3.6 Abrasion resistance. After being subjected to the abrasion test specified in 4.5.2.6,
haze shall be not greater than 6 percent and the transmittance shall not decrease by more than
4 percent. For example, an initial value of 20 percent transmittance shall not decrease to less than
16 percent.
3.4.4 Environmental requirements.
3.4.4.1 Radiation-induced damage resistance. When the lenses are tested as specified in
4.5.3.2 and 4.5.3.3, transitory or permanent radiation-induced changes in the optical density or
transmittance shall not occur at power levels up to 100 millijoules (mj).
3.4.4.2 High temperature. When tested as specified in 4.5.3.4, the spectacles shall withstand
high temperature stresses, with no delamination at lenses or coatings.
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