Optical glass for precision molding having high refractive index

Abstract

An optical glass for precision molding having a high refractive index (nd) and a low yield temperature (At). The optical glass comprises, as glass components in wt %, 64 to 83% of Bi2O3; 4 to 17% of B2O3; 0 to 12% of GeO2 (wherein the total of B2O3 and GeO2 is 10 to 20%); 0 to 7% of La2O3; 0 to 7% of Gd2O3 (wherein the total of La2O3 and Gd2O3 is 1 to 13%); 0 to 4% of ZrO2; 0 to 5% of Ta2O5; 0 to 15% of ZnO; 0 to 2% of Sb2O3; and 0 to 1% of In2O3. The optical glass has optical constants, that is, a refractive index (nd) of 2.05 to 2.25 and an Abbe number (νd) of 15 to 22, and a yield temperature (At) of 510° C. or less.

Description

EXAMPLE

Hereafter, an optical glass of the present invention is described in detail by referring to Examples, but the present invention is not limited to these Examples.

Optical glasses of Examples 1 to 10 were produced by: weighing each raw material compound so that each Example had a proportion of component composition as shown in the column of composition in the following Table 1; sufficiently mixing the raw material compounds; inputting them in a platinum crucible to melt at 900 to 1150° C. by an electric furnace; stirring the mixture for homogenization at appropriate timings; clarifying and then casting the mixture in a metallic mold preheated at a suitable temperature; and gradually cooling. In the tables, each component for composition is expressed in wt % and mol %.

The obtained optical glasses of Examples 1 to 10 were measured by known methods in terms of optical constants (refractive index (nd) and Abbe number (νd)) and the yield temperature (At/° C.). Results are shown in Table 1 together with the composition of each optical glass.

	TABLE 1
	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Example 7	Example 8	Example 9	Example 10
Composition	GeO2	5.61	4.84	10.15	8.60	—	1.13	4.50	2.16	4.00	8.64
		(12.66)	(9.09)	(24.58)	(23.29)		(2.68)	(10.54)	(5.36)	(9.34)	(21.16)
	B2O3	11.09	9.62	7.84	5.34	15.11	13.88	13.0	12.28	13.00	7.90
		(37.58)	(27.11)	(28.54)	(21.74)	(53.12)	(49.51)	(45.74)	(45.71)	(45.64)	(29.08)
	La2O3	5.65	2.75	2.64	2.77	2.73	5.50	—	1.42	2.00	5.20
		(4.09)	(1.66)	(2.05)	(2.40)	(2.05)	(4.19)		(1.13)	(1.50)	(4.10)
	Gd2O3	5.79	2.82	2.71	2.84	2.80	—	2.00	1.42	2.00	5.33
		(3.77)	(1.53)	(1.89)	(2.22)	(1.89)		(1.35)	(1.01)	(1.35)	(3.77)
	ZrO2	2.76	0.83	0.80	0.84	0.83	0.83	—	0.47	0.50	1.10
		(5.28)	(1.33)	(1.64)	(1.92)	(1.64)	(1.67)		(0.99)	(0.99)	(2.28)
	Bi2O3	64.73	64.31	74.12	77.78	76.73	77.15	78.50	81.31	78.50	68.38
		(32.79)	(27.11)	(40.30)	(47.26)	(40.30)	(41.10)	(41.26)	(45.24)	(41.18)	(37.61)
	Ta2O5	3.74	1.82	1.74	1.83	1.80	1.51	2.00	0.94	—	3.45
		(2.00)	(0.81)	(1.00)	(1.17)	(1.00)	(0.85)	(1.11)	(0.56)		(2.00)
	ZnO	0.63	13.0	—	—	—	—	—	—	—	—
		(1.83)	(31.36)
Characteristic	nd	2.07313	2.06095	2.12609	2.19767	2.07384	2.09480	2.09324	2.12005	2.09293	2.11951
value	νd	20.34	19.29	18.07	16.28	19.54	18.87	18.73	17.96	18.74	20.98
	At/° C.	509	463	461	440	467	454	454	438	451	489
*Unit of Composition is wt % in this Table (mol % notation in brackets).

Table 1 shows that each optical glass of the present invention shown in Examples has a refractive index (nd) of 2.05 to 2.25 and an Abbe number (νd) of 15 to 22, and a yield temperature (At) of 510° C. or less.

Claims

1. An optical glass for precision molding comprising, as glass components in wt %, 64 to 83% of Bi2O3;4 to 17% of B2O3;0 to 12% of GeO2 (wherein the total of B2O3 and GeO2 is 10 to 20%);0 to 7% of La2O3;0 to 7% of Gd2O3 (wherein the total of La2O3 and Gd2O3 is 1 to 13%);0 to 4% of ZrO2;0 to 5% of Ta2O5;0 to 15% of ZnO;0 to 2% of Sb2O3; and0 to 1% of In2O3,the optical glass having optical constants, that is, a refractive index (nd) of 2.05 to 2.25 and an Abbe number (νd) of 15 to 22, and a yield temperature (At) of 510° C. or less.