Dome and window for missiles and launch tubes with high ultraviolet transmittance

A missile launch tube window comprising:

• a transparent, sintered polycrystalline body comprising magnesia-alumina spinel having a transmittance per 1.88 mm thickness at all wavelengths in the wavelength region between 0.4 microns and 0.5 microns of at least about 82%, having a flexural strength of at least about 20,000 psi and having a knoop hardness of at least about 1350 kg mm.sup.-2;
• said launch tube window being formed in the shape of a substantially flat disk.

A guided missile comprising:

• a missile propulsion system for moving the missile in a controllable direction;
• an optical guidance system operably connected to said propulsion system for controlling said direction of said movement;
• a dome covering at least a portion of said optical guidance system, the dome comprising a transparent, sintered polycrystalline body comprising magnesia-alumina spinel, having a transmittance per 1.88 mm thickness at all wavelengths in the wavelength region between 0.4 microns and 0.5 microns of at least about 82%, at all wavelengths in the wavelength range between 3.0 microns and 4.0 microns of at least about 81%, and at all wavelengths in the wavelength range between 4 microns and 5 microns of at least about 76%, having a flexural strength of at least about 20,000 psi and having a knoop hardness of at least about 1350 kg mm.sup.-2.

A missile launch tube comprising:

• a tubular-shaped member having a sealable opening;
• a window attached to said tubular member in a position to seal said sealable opening, said window comprising a transparent, sintered polycrystalline body comprising magnesia-alumina spinel, having a transmittance per 1.88 mm thickness at all wavelengths in the wavelength region between 0.4 microns and 0.5 microns of at least about 82%, at all wavelengths in the wavelength range between 3.0 microns and 4.0 microns of at least about 81%, and at all wavelengths in the wavelength range between 4 microns and 5 microns of at least about 76%, having a flexural strength of at least about 20,000 psi and having a knoop hardness of at least about 1350 kg mm.sup.-2.