The finished optical components are to be used for fire control instruments such as sights, telescopes, periscopes and range finders either as individual elements, partial or complete systems, and assembled or unassembled, as required by contract.

The adhesive covered by this specification is intended for bonding optical elements in military optical systems.

The magnesium fluoride coating covered by this specification is applied to the surface of optical elements to increase light transmission and reduce reflections. The requirements defined by Figures 1C and 2C for transmission difference and maximum reflectance respectively, apply to coatings employed in the visible spectrum. Optical requirements for magnesium fluoride coatings used in ultraviolet or infrared spectral applications must be independently determined and specified.

The durability requirements established in this specification insure a level of quality consistent with military requirements. Additional durability requirements to confirm the suitability of a magnesium fluoride coating in a particular application should be considered when it is established that a coated optical element (coating and substrate) will exhibit the capability to satisfy the additional requirements.

This specification permits certain cosmetic defects, such as stains, on coated optical elements. This requirement is established to permit the acceptance of coated elements where the defect is strictly aesthetic and the optical and durability properties of the coating are not impaired. The attention of optical designers is directed to this requirement on an individual basis when cosmetic defects cannot be tolerated on the optical elements.

The adhesive systems covered by this specification are intended primarily for use in bonding glass to metal. The materials to be bonded include glass prisms and other optical elements to their metal supports in optical fire control instruments. For maximum reliability and environmental resistance especially to humid conditions, the Type I adhesive system is recommended. Both the Types I and II adhesive systems may be used for general purpose bonding of materials such as aluminum, stainless steel, brass, bronze, plastics, glass, etc., to themselves or in dissimilar combinations. Various bond line thickness may be used for bonded assemblies, however, for the structural bonding of glass prisms to metal mounts a bond line thickness of .036 to 0.41 cm is recommended.

Minor assemblies bonded with the adhesive systems of this specification should be thoroughly evaluated for the effect of the adhesive on the optical properties of the assemblies.

The sealing compounds covered by this specification are intended for use in sealing metal to metal, glass to metal and acrylic to metal and for general purpose as deemed necessary by the using activity. This material is not to be used as an integral fuel tank or pressure cabin sealant.