Nov. 11, 1947. KUANHAN SUN ETAL v2,430,540 CADMIUM-LANTHANUM-BORATE GLAS S Filed Aug. 9, 1946

KUAN-HAN SUN THOMAS E. C'ALLEAR .INVENTORS

. ATTORNEY Patented Nov. 11, 1947 2,430,540

UNITED STATES PATENT, OFFICE 2,430,540 CADMIUM-LANTHANUM-BORATE GLASS Kuan-Han Sun and Thomas E. Callear, Roches ter, N. Y., assignors to Eastman Kodak Com pany, Rochester, N. Y., a corporation of New Jersey Application August 9, 1946, Serial No. 689,532 ~ 7 Claims. (01. 106-47) 1 2 This invention relates to improved optical glass components CdO and 301.5, respectively, and and particularly to cadmium-lanthanum-borate LaOm as such. glass having a high refractive index and a mod In making these glasses, the batch in powdered erate Abbe Value. - form is mixed uniformly and placed in a, platinum Glasses having optical properties in these vessel. The melting temperature is in the range ranges are usually composed largely of relatively 1200-1300" C. A fairly ?uid liquid results after costly ingredients such as the oxides of lantha about a half hour for a melt of the order of 100 num, thorium, and tantalum, We have found that grams. The liquid may be shaken or stirred and by substituting cadmium in relatively large pro poured into a mold previously heated to 400-600° portion, chemically durable optical glasses with 10 C, and allowed to cool slowly. A clear, colorless similar refractive properties may be obtained. glass which is durable against moisture attack The chief components in the present new glasses is obtained. are the oxides of cadmium, lanthanum, and Having thus described our invention, what we boron. We do not exclude the use in small claim is: _ 1 amounts of other oxides known to be useful in 15 1. An optical glass resulting from a batch over glass compositions, and the examples given below ninety per cent by weight or 95 cationic per cent, include formulas with thorium or tantalum oxide. of which consists of the oxides of cadmium, The boundary lines of glass formation region lanthanum, and boron. of the system CdO—LaO1.5—BO1.5 are shown in 2. An optical glass resulting from a batch over the accompanying ?gure for both weight per cent 20 ninety per cent by weight or 95 cationic per cent, and cationic per cent. In order to obtain optical of which consists of the oxides of cadmium, properties in the useful ?eld mentioned, the lanthanum, and boron each of said oxides being amount of cadmium oxide present should be present in an amount greater than twenty per greater than 5 weight per cent or 2 cationic per cent by weight. cent and of lanthanum oxide, greater than 25 3. An optical glass resulting from a batch over 5 weight per cent or 2 cationic per cent, ninety per cent by weight or 95 cationic per cent the sum of the two being in all cases greater of which consists of the oxides of cadmium, lan than 50 weight per cent or 20 cationic'per cent. thanum, and boron, of which boron oxide is at Since LazOs; B203, etc., are empirical formulas, least twenty-four weight per cent or 56 cationic it is equally expedient and more convenient, par 30 per cent and cadmium and lanthanum oxides are ticularly in using cationic percentage or electro. each present in an amount greater than ?ve positive atomic percentage, to adopt the form weight per cent, or 3 cationic per cent. LaO1.5; 1301.5, etc. 4. An optical glass resulting from a batch con The following table gives three illustrative ex taining by weight at least twenty-four per cent amples of glasses with their batch compositions 35 boron oxide and at least 5 per cent of each of in weight percentages (W) and cationic percent cadmium and lanthanum oxides. ages (C): 5. An optical glass resulting from a batch con taining by weight at least twenty-four per cent boron oxide, at least 5 per cent of each of cad 40 mium and lanthanum oxides, the total of the Q o lanthanum and cadmium oxides being at least 50 weight per cent. . 6. An optical glass resulting from a batch con taining at least 56 cationic per cent boron oxide, 45 at least 3 cationic per cent of each of cadmium and lanthanum oxides. 7. An optical glass resulting from a batch con taining at least 56 cationic per cent boron oxide, at least 3 cationic per cent of each of cadmium The index of refraction for the D line (no) and 50 and lanthanum oxides, the total of the lanthanum the Abbe value (/4) are given for two of the ex and cadmium oxides being at least 20 cationic per amples. cent. As is usual in glass making, various compounds KUAN-HAN SUN. other than the oxides may be used. For conven THOMAS E. CALLEAR. ience, CdCOs and. H3303 may be used for the 55