# US 8,785,339 B2 · Optical glass

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- Number: US 8,785,339 B2
- Document ID: US8785339B2
- Status: Granted
- Kind: B2
- Application number: 13/909,122
- Filed: 2013-06-04
- Published: 2013-10-17
- Granted: 2014-07-22
- Earliest claimed: 2008-01-31
- Assignees: Hoya Corporation
- Applicants: Hoya Corporation
- Inventors: Xuelu Zou; Yoshio Nojima; Hiroki Takazawa
- Web page: https://patentgrep.com/patent/US8785339B2

## CPC

- C03C 3/097: containing phosphorus, niobium or tantalum
- C03B 11/00: Pressing {molten} glass {or performed glass reheated to equivalent low viscosity without blowing (shaping molten glass by a press-blow process C03B9/00, e.g. C03B9/193; re-forming shaped glass C03B23/00; re-heating the performed glass C03B29/00; transporting the performed or pressed glass during its manufacture C03B35/00)}
- C03B 11/122: {Heating}
- C03C 3/062: with less than 40% silica by weight
- C03C 3/064: containing boron
- C03C 3/066: containing zinc
- G02B 1/00: Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An optical glass comprising, by mass %, 12 to 40% of SiO2, 15% or more but less than 42% of Nb2O5, 2% or more but less than 18% of TiO2, (provided that Nb2O5/TiO2 is over 0.6), 0.1 to 20% of Li2O, 0.1 to 15% of Na2O, and 0.1 to 25% of K2O, and having an Abbe's number νd of 20 to 30, a ΔPg,F of 0.016 or less and a liquidus temperature of 1,200° C. or lower.

## Claims

### Claim 1

An optical glass comprising, by mass %,
12 to 40% of SiO2,
15% or more but less than 42% of Nb2O5,
2% or more but less than 12% of TiO2,
(provided that Nb2O5/TiO2 is equal to or more than 3.49),
0.1 to 20% of Li2O,
0.1 to 15% of Na2O, and
0.1 to 25% of K2O,
the optical glass having an Abbe's number νd of 20 to 30, a refractive index nd of 1.87 to 1.90, ΔPg,F of 0.016 or less and a liquidus temperature of 1,200° C. or lower.

### Claim 2 (depends on 1)

The optical glass as recited in claim 1, which contains, as optional components,
0 to 10% of B2O3,
0 to 20% of ZrO2,
0 to 20% of WO3,
0 to 13% of CaO,
0 to 13% of SrO,
0 to 20% of BaO,
(provided that the total content of CaO, SrO and BaO is 0 to 25%),
0 to 13% of ZnO,
0 to 3% of La2O3,
0 to 3% of Gd2O3,
0 to 3% of Y2O3,
0 to 3% of Yb2O3,
0 to 10% of Ta2O5,
0 to 3% of GeO2,
0 to 10% of Bi2O3, and
0 to 10% of Al2O3,
the total content of Nb2O5 and TiO2 being 30 to 60%, the content of K2O being 0.1 to 15%, and the total content of Li2O, Na2O and K2O being 1 to 25%.

### Claim 3 (depends on 1)

The optical glass as recited in claim 1, which contains Sb2O3 in an amount of 0 to 2% and SnO2 in an amount of 0 to 2%, these amounts being based on a glass composition excluding Sb2O3 and SnO2.

### Claim 4 (depends on 1)

The optical glass as recited in claim 1, which has a partial dispersion ratio, Pg,F, of 0.580 to 0.620.

### Claim 5 (depends on 1)

The optical glass as recited in claim 1, which has a glass transition temperature of less than 600° C.

### Claim 6 (depends on 1)

A press-molding glass material formed of the optical glass recited in claim 1.

### Claim 7 (depends on 6)

A process for producing an optical element blank, which comprises softening the glass material recited in claim 6 under heat and press-molding the glass material.

### Claim 8 (depends on 7)

A process for producing an optical element, which comprises grinding and polishing the optical element blank produced by the process recited in claim 7.

### Claim 9 (depends on 6)

A process for producing an optical element, which comprises heating the press-molding glass material recited in claim 6 and precision press-molding it with a press mold.

### Claim 10 (depends on 9)

The process for producing an optical element as recited in claim 9, which comprises introducing the glass material into the press mold and heating said mold and the glass material together.

### Claim 11 (depends on 9)

A process for producing an optical element as recited in claim 9, which comprises heating the glass material and introducing the glass material to a pre-heated press mold to carry out the precision press-molding.

### Claim 12 (depends on 1)

An optical element formed of the optical glass recited in claim 1.

### Claim 13 (depends on 1)

A process for producing an optical element blank, which comprises supplying a molten glass to a press mold and press-molding the molten glass,
wherein glass raw materials prepared so as to obtain the optical glass recited in claim 1 are melted under heat and the resultant molten glass is press-molded.