Transmission of near-infrared energy by some two- and three-component glasses

Abstract

Most silicate glasses have a region of absorption for radiant energy at wavelengths lon ge r t han 2.7 micron s. This absorption has been found to be cau sed by t he presence of water and CO2 in t he glass. Means for removin g much of this ab~o~ption from. so me glas?es hav~ been d eveloped. Also, it has been found t hat glasse.s contall1ll1g lead oXide or banum oXide, or combinations of the t wo , do not appear to retall1 as IToJuch. ,yater a s m?st o~he r glasse? . A soda-lead oxide-silica glass and a barium oxide-lead oXide-SIlIca glass with hi gh tran smi SSIOn for near-infrared energy have been developed .

Infrared transmittance of some calcium aluminate and germanate glasses

“…Previously reported glasses with higher silica content cut off between 5.0 and 5.5 J.L [2] . A reduction in silica content also materially increased the transmittance of the glass beyond 3.25 J.L [3] . Figure 3 shows the transmittance curve for a low silica eu tec tic glass, reported by 2' .1 eM urdie and Insley [17], melt 2-5l.…”

“…The great advan tage of th e dry-a ir trratmen t to gla sses h as been shown in a previou s paper [3 ]. Figure 21 com pares th c transmittan ce of a lead sili cate glass C-1284 wi th tha t for the m olar equivalen t lrad gel'manate glass C-1526.…”

“…During Lhe finin g of several of the glasses, dry air was introduced into th e bottom of the m el t by m eans of a platinum Lube for 2 hI'. T his procedure is referred to for br evity, as the " dry-air treatment" [3]. With ~om e glasses of low viscosity, this treatment is very effective in removing wator vapor and poss ibly other soluble gases.…”

“…B oth \ err given th e dry -air treatmen t.7 H ad glass C-1284 no t been givcn the dry-a il' t rea tmen t, its transm ittan ce at 2.9 to 3.0 jJ. would only h ave bren 30 to 40 percen t [3]. Ou t to 3.6 jJ., the silicate glass C-1284 h as the high er transmittance; b eyond 3 .6 fJ-th e german ate glass C-1526 h as the sup erior tran smittan ce.…”

“…The st udy of lhe transm ittance of infrared energy b.\-glass [1,2,3] '~ at the National Bureau of tandarcls has resulted in t he p reparation of glasses departing from t he ol'clinar)' glass compositions. The common glass-forming oxides ar e B20 3, P 20 5, and S IO~.…”