Industrial Optical Glass

an inorganic glass product used for changing the direction or spectral composition of a light flux.

According to the nature of the change in direction of the light flux, industrial optical glasses are divided into the following types: refracting (for example, lenses for beacons, traffic lights, and automobile headlights), reflecting (for example, spherical, parabolic, and hyperbolic mirrors) and diffusing (for example, ceiling fittings and globes of lamps). The refraction and reflection of light are achieved by the shape of the objects, while scattering is achieved either by frosting of the glass surface or by opacification. For opacification 3–7 percent of the composition of the glass consists of fluorine or phosphorus compounds.

Colored industrial optical glasses are divided into five groups: red, yellow, green, blue, and milk-white. Selenium and compounds of cadmium, copper, cobalt, and chromium are used to color the glasses. Colored industrial optical glasses are used mainly for transportation signals.

The composition of industrial optical glasses includes SiO₂(60–80 percent) and oxides of, for example, aluminum, calcium, and magnesium. B₂0₃ is added to the glass to improve its heat resistance. Glasses used for the absorption or transmission of ultraviolet, infrared, or X-ray radiation as well as glasses for the absorption of gamma rays and thermal neutrons are also classified as industrial optical glasses.