Glass with High Refractive Index for Fiber Optic Imaging Element with Medium-Expansion and Fabrication Method Therefor

Abstract

The present invention discloses a glass with high refractive index for fiber optic imaging elements with medium-expansion and fabrication method therefor, the glass comprising the following components in percentage by weight: SiO.sub.2 5-9%, Al.sub.2O.sub.3 0-1%, B.sub.2O.sub.3 23-28%, CaO 0-3%, BaO 6-12%, La.sub.2O.sub.3 30-34%, Nb.sub.2O.sub.5 4-8%, Ta.sub.2O.sub.5 0-1%, Y.sub.2O.sub.3 0-1%, ZnO 4-9%, TiO.sub.2 4-8%, ZrO.sub.2 4-6%, SnO.sub.2 0-1%. The present invention further provides a fabrication method for the glass with a high refractive index, comprising: putting raw materials quartz sand, aluminum hydroxide, boric acid or boric anhydride, calcium carbonate, barium carbonate or barium nitrate, lanthanum oxide, niobium oxide, tantalum oxide, yttrium oxide, zinc oxide, titanium dioxide, zirconium oxide and stannic oxide, etc. into a platinum crucible according to the requirement of dosing, melting at a high temperature, cooling and fining, leaking and casting to form a glass rod, and then annealing, cooling and chilling the molded glass rod.

Claims

1. A composition of glass with high refractive index for fiber optic imaging elements with medium-expansion, comprising the following components in percentage by weight: TABLE-US-00004 SiO.sub.2 5-9% Al.sub.2O.sub.3 0-1% B.sub.2O.sub.3 23-28% CaO 0-3% BaO 6-12% La.sub.2O.sub.3 30-34% Nb.sub.2O.sub.5 4-8% Ta.sub.2O.sub.5 0-1% Y.sub.2O.sub.3 0-1% ZnO 4-9% TiO.sub.2 4-8% ZrO.sub.2 4-6% SnO.sub.2 0-1% ; wherein the glass with high refractive index has a refractive index of 1.80-1.82, a coefficient of mean linear thermal expansion of (68 ± 5) × 10.sup.-7/°C in the range of 30-300° C., a strain point temperature of more than 600° C., and a devitrification temperature of more than 820° C.

2. The composition according to claim 1, comprising the following components in percentage by weight: TABLE-US-00005 SiO.sub.2 9% Al.sub.2O.sub.3 1% B.sub.2O.sub.3 23% BaO 12% La.sub.2O.sub.3 34% Nb.sub.2O.sub.5 4% Ta.sub.2O.sub.5 0.5% ZnO 4% TiO.sub.2 8% ZrO.sub.2 4% SnO.sub.2 0.5% .

3. (canceled)

4. A fabrication method for the glass with high refractive index for fiber optic imaging elements with medium-expansion with the composition according to claim 1, comprising the following steps: (1) putting quartz sand, aluminum hydroxide, boric acid or boric anhydride, calcium carbonate, barium carbonate or barium nitrate, lanthanum oxide, niobium oxide, tantalum oxide, yttrium oxide, zinc oxide, titanium dioxide, zirconium oxide and stannic oxide into a platinum crucible according to the requirement of dosing; (2) melting at a first preset temperature, stirring in the melting process, then cooling to a second preset temperature and fining to obtain a fining glass melt; (3) allowing the fining glass melt to flow down through a leaking port, and casting the fining glass melt in a mold to form a glass rod; (4) annealing the molded glass rod in an annealing furnace, and then cooling to room temperature along with the furnace.

5. The method according to claim 4, wherein the first preset temperature is 1350-1450° C.; the time of melting is 4-8 hours; the stirring in the melting process is 1-2 times; the second preset temperature is 1300-1340° C.; the time of fining is 1-2 hours.

6. The method according to claim 4, wherein the annealing process is preserving heat for 1 hour at 600-650° C., and cooling to 60° C. from 600-650° C. for 12 hours.

7. A glass with high refractive index for fiber optic imaging elements with medium-expansion, wherein the glass with high refractive index is fabricated by using the fabrication method according to claim 4.

8. The glass with a high refractive index for fiber optic imaging elements with medium-expansion according to claim 7, wherein the glass with high refractive index is fabricated into an optical glass having a viscosity curve with strong liquid fragility in the viscosity range of 10.sup.2-10.sup.13 dPas.

9. A fiber optic imaging element, comprising a fiber optical faceplate, a fiber optical image inverter, a fiber optical taper and a fiber optical bundle for image transmission, wherein the fiber optic imaging element is fabricated by a drawing process of combing a core glass rod and a cladding glass tube, and the core glass rod is fabricating by using the glass with a high refractive index according to claim 7.

10. (canceled)

11. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1 is a comparison diagram of tests of the coefficient of thermal expansion of embodiments in the present invention and a glass with high coefficient of thermal expansion.

DETAILED DESCRIPTION

[0043] In order to make the purposes, technical solutions and advantages of the present invention to be more clarity, the present invention will be further described in detail with reference to detailed embodiments, but not limited by the description.

[0044] The measured parameters, measuring methods and instruments of the glass with high refractive index used for the fiber optic imaging element with medium-expansion of the present invention are as follows: [0045] (1) refractive index n.sub.D [the refractive index of glass at λ=589.3 nm]; [0046] (2) the average coefficient of thermal expansion α.sub.30/.sub.300[10.sup.-7/°C] at 30-300° C.

[0047] Wherein the refractive index n.sub.D of glass is measured by a refractive index device; the coefficient of linear thermal expansion at 30-300° C. is measured by a horizontal dilatometer using the method specified in ISO 7991, and expressed by a coefficient of mean linear thermal expansion. Chemical compositions (wt.%) and glass performances of the embodiments are detailed listed in Table 1.

TABLE-US-00003 chemical compositions (wt.%) and physical values of the glass samples composition embodiment 1 embodiment 2 embodiment 3 embodiment 4 embodiment 5 SiO.sub.2 9 7 7 8 5 Al.sub.2O.sub.3 1 0 0 0 5 B.sub.2O.sub.3 23 25 is 24 28 CaO 0 0 0 0 3 BaO 12 8.4 10 7 6 La.sub.2O.sub.3 34 32.8 32 34 30 Nb.sub.2O.sub.5 4 7 6 7.5 8 Ta.sub.2O.sub.5 0.5 0.5 0.5 0 0.5 Y.sub.2O.sub.3 0 0 0 0.5 0 ZnO 4 8 8 7 9 TiO.sub.2 8 7 6 5 4 ZrO.sub.2 4 4 5 6 6 SnO.sub.2 0.5 0.26 0.5 1 0.5 α.sub.30/300[10.sup.-7/°C] 70.234 67.918 66.830 71.094 68.607 n.sub.D 1.80 1.82 1.82 1.82 1.81

[0048] The raw materials used in the following embodiments and their requirements are as follows:

[0049] Quartz sand (high purity, 150 .Math.m oversize is less than 1%, 45 .Math.m undersize is less than 30%, the content of Fe.sub.2O.sub.3 is less than 0.01 wt.%), aluminum hydroxide (analytical purity, average particle size 50 .Math.m), boric acid or boron anhydride (400 .Math.m oversize is less than 10%, 63 .Math.m undersize is less than 10%), calcium carbonate (analytical purity, average particle size 250 .Math.m), barium carbonate (analytical purity, purity ≥99.0%), lanthanum trioxide (5N), niobium pentoxide (5N), tantalum pentoxide (5N), yttrium trioxide (5N), zinc oxide (analytical purity), titanium dioxide (chemical purity), zirconium oxide (analytical purity), stannic oxide (analytical purity).

[0050] Referring to FIG. 1, CTE in figures is Coefficient of Thermal Expansion, which test range is 30-300° C. The coefficient of thermal expansion of the comparative high expansion glass is 91.324×10.sup.-7/°C, and the coefficient of thermal expansion of embodiment 1 to embodiment 5 in the present invention respectively is 70.234×10.sup.-7/°C, 67.918×10.sup.-7/°C, 66.830×10.sup.-7/°C, 71.094×10.sup.-7/°C, 68.607×10.sup.-7/°C.

[0051] The present invention will be further described below through the specific preparation method of embodiments:

Embodiment 1

[0052] Firstly, raw materials are selected according to the glass composition of embodiment 1 in Table 1, and oxides of elements with valence state change in the glass raw materials such as Fe.sub.2O.sub.3 are strictly controlled, and the content of Fe.sub.2O.sub.3 in a finished product of glass is less than 100 PPm. The glass batch meets the chemical compositions of glass in Table 1, and then quartz sand, aluminum hydroxide, boric acid, calcium carbonate, barium carbonate, lanthanum oxide, niobium oxide, tantalum oxide, yttrium oxide, zinc oxide, titanium dioxide, zirconium oxide and stannic oxide are put into a platinum crucible and melted for 6 hours at 1400° C. In the glass melting process, the glass is stirred twice to melt evenly. After melting, the glass is cooled to 1320° C. and fining for 2 hours to obtain a molten glass. Thereafter, the molten glass is cast into a test specimen according to the specified requirements, then annealing is carried out and the annealing process is that preserving heat for 1 hour at 625° C., and cooling to 60° C. from 625° C. for 12 hours, and then cooling to room temperature along with the furnace. Its test performance is shown in Table 1, (1) a refractive index is 1.80; (2) a coefficient of mean linear thermal expansion at 30-300° C. is 70.234×10.sup.-7/°C.

Embodiment 2

[0053] The actual composition of glass refers to embodiment 2 in Table 1, and uses the same requirements for raw material as embodiment 1. Quartz sand, aluminum hydroxide, boric anhydride, calcium carbonate, barium nitrate, lanthanum oxide, niobium oxide, tantalum oxide, yttrium oxide, zinc oxide, titanium dioxide, zirconium oxide and stannic oxide are put into a platinum crucible and melted for 8 hours at 1350° C. In the glass melting process, the glass is stirred once to melt evenly. After melting, the glass is cooled to 1300° C. and fining for 1 hour to obtain a molten glass. Thereafter, the molten glass is cast into a test sample according to the specified requirements, then annealing is carried out and the annealing process is that preserving heat for 1 hour at 650° C., and cooling to 60° C. from 650° C. for 12 hours, and then cooling to room temperature along with the furnace. The test conditions used are the same as embodiment 1, and the basic performances of samples are shown in Table 1. (1) a refractive index is 1.82; (2) an coefficient of mean linear thermal expansion at 30-300° C. is 67.918×10.sup.-7/°C.

Embodiment 3

[0054] The actual composition of glass refers to embodiment 3 in Table 1, and uses the same raw material and requirements for raw material as embodiment 1. Raw materials are melted for 4 hours at 1450° C. In the glass melting process, the glass is stirred twice to melt evenly. After melting, the glass is cooled to 1340° C. and fining 2 hours to obtain a molten glass. Thereafter, the molten glass is cast into a test sample according to the specified requirements, then annealing is carried out and the annealing process is that preserving heat for 1 hour at 600° C., and cooling to 60° C. from 600° C. for 12 hours, and then cooling to room temperature along with the furnace. The test conditions used are the same as embodiment 1, and the basic performances of samples are shown in Table 1. (1) a refractive index is 1.82; (2) an coefficient of mean linear thermal expansion at 30-300° C. is 66.830×10.sup.-7/°C.

Embodiment 4

[0055] The actual composition of glass refers to embodiment 4 in Table 1, uses the same raw material and requirements for raw material as embodiment 1 and adopts the same melting process system and test conditions as embodiment 1. The basic performances of samples are shown in Table 1. (1) a refractive index is 1.82; (2) a coefficient of mean linear thermal expansion at 30-300° C. is 71.094×10.sup.-7/°C.

Embodiment 5

[0056] The actual composition of glass refers to embodiment 5 in Table 1, uses the same raw material and requirements for raw material as embodiment 1 and adopts the same melting process system and test conditions as embodiment 1. The basic performances of samples are shown in Table 1. (1) a refractive index is 1.81; (2) a coefficient of mean linear thermal expansion at 30-300° C. is 68.607×10.sup.-7/°C.

[0057] From the data obtained in embodiments, it can be known that the glass with high refractive index for fiber optic imaging elements with medium-expansion of the present invention has the advantages of high refractive index and does not contain heavy metal oxides that are seriously harmful to the environment, and is suitable for fabricating fiber optic imaging elements. The fiber optic imaging element can be a fiber optical faceplate, a fiber optical image inverter, a fiber optical taper and a fiber optical bundle for image transmission, etc., wherein the core glass used is fabricated from the glass with high refractive index for fiber optic imaging elements with medium-expansion of the present invention.

[0058] In addition, with the development trend of miniaturization of optical technology and photoelectronic technology, a glass with a high refractive index has an excellent chemical stability, a low coefficient of thermal expansion, and an excellent transmission can shorten the focal length of lens to achieve that shorten the size of the component or lens assembly. The glass with a high refractive index of the present invention can be used as an optical glass for this type of technology.

[0059] The above descriptions are only exemplary embodiments of the present invention, and are not intended to limit the present invention. The protection scope of the present invention is claimed by the claims, and any modification, equivalent replacement, improvement, etc. made to the present invention by those skilled in the art within the spirit and protection scope of the present invention should be included in the protection scope of the present invention.