P, which provide protection against multiple fixed laser wavelengths.

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MIL-PRF-29580C

principle meridian of the lens placed across the test aperture can be determined to within 0.06

diopter. The spectacle lenses shall meet the requirements specified in 3.4.2.1.

4.5.1.2 Prismatic deviation (optical power).

4.5.1.2.1 Vertical prismatic deviation. The spectacles shall be tested for vertical prismatic

deviation using the test method described in 4.5.1.1. Base up prism shall be designated positive

(+) and base down prism shall be designated negative (-). The vertical prismatic deviation shall

be calculated by determining the algebraic sum and difference between the amount of prism at the

design eyepoint of the right lens and the amount of prism at the design eyepoint of the left lens

and shall meet the requirements specified in 3.4.2.2.1.

4.5.1.2.2 Horizontal prismatic deviation. The spectacles shall be tested for horizontal

prismatic deviation using the method described in 4.5.1.1. Base out prism shall be designated

positive (+) and base in prism shall be designated negative (-). The horizontal prismatic deviation

shall be calculated by determining the algebraic sum and difference between the amount of prism

at the design eyepoint of the right lens and the amount of prism at the design eyepoint of the left

lens and shall meet the requirements specified in 3.4.2.2.2.

4.5.1.3 Spherical and cylindrical power. The spectacles shall be tested for spherical and

cylindrical power using the method described in 4.5.1.1 and shall meet the requirements specified

in 3.4.2.3.

4.5.1.4 Lens defects. The spectacle lenses shall be inspected for irregularities and material

defects affecting optical qualities by examining each lens against the NIST Special Publication 374

or NIST Circular 533 high contrast chart or equivalent. The lenses shall meet the requirements

specified in 3.4.2.4.

4.5.1.5 Lens fit. The contact area between the frame and lens of the spectacles shall be

inspected with a strong, neutral, non-glaring light behind the spectacles. Any visible light between

the frame and lens indicates a space exists between the frame and the lens. The spectacles shall

meet the requirements specified in 3.4.2.5.

4.5.1.6 Curvature. The outside curvature of the spectacle lenses shall be measured using a

Geneva lens measure or equivalent. Three measurements shall be made on each lens to the

nearest 0.125 diopter. The outside curvature of the lenses shall meet the requirements specified in

3.4.2.6.

4.5.2 Spectral transmittance inspections.