Optical glass, glass preform, optical element and optical instrument

Abstract

The invention provides optical glass, which is composed of (by weight): 4-20% of SiO2, 10-30% of B2O3, 10-35% of La2O3, 10-40% of BaO, 0.5-1% OF ZrO2, 0.1-5% of Nb2O5, and 0.5-15% of SrO, wherein theratio of SiO2 / B2O3 is 0.4-1.3. The refractive index of the optical glass is 1.65-1.73, and the abbe number is 47-55. Meanwhile, the optical glass has low thermal refractive index coefficient and excellent resistance to crystallization and chemical stability.

Description

technical field [0001] The invention relates to an optical glass, in particular to a lanthanum-containing optical glass with a refractive index of 1.65-1.73 and an Abbe number of 47-55, as well as a glass preform, an optical element and an optical instrument made of the optical glass . Background technique [0002] In the prior art, glass with a refractive index of 1.65-1.73 and an Abbe number of 47-55 belongs to medium refractive index glass, and is widely used in various lenses. In recent years, vehicle-mounted lens equipment has developed vigorously. Compared with general photography and other applications, the quality of vehicle-mounted lenses is closely related to safety. Therefore, vehicle-mounted lenses place more emphasis on the reliability of equipment, especially those exposed outside the vehicle body, which need to withstand harsh conditions. Working environment, such as reversing camera, front-view camera, rear-view mirror auxiliary camera, etc. [0003] The pr...

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Problems solved by technology

[0009] However, if the lanthanum crown glass with the above-mentioned refractive index and Abbe number needs to achieve a temperature coefficient of refractive index lower than 0, the component design needs to be different from the conventional ones, which usually leads to poor devitrification resistance and striations in the production. Problems such as bubbles are not easy to eliminate

[0010] If the anti-devitrification ability of the glass is poor, it will firstly increase the difficulty of the production of glass blanks, resulting in a decline in the yield rate, and even cannot be produced normally in serious cases; secondly, crystal precipitation is prone to occur during the secondary molding process, resulting in a decline in the yield rate. Can't even do secondary molding

For glass materials used in the automotive field, if the yield rate of the glass is low, and the cold processing method cannot be used for secondary molding, the cost increase will lead to unacceptable

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