Medium-Expansion High-Refractive Index Glass for Fiber Optic Imaging
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Solution Overview
Problem
Current fiber optic imaging elements in China have a high expansion coefficient that is far from the thermal expansion matching degree of Kovar alloy, leading to instability and reduced service life of low-level-light image intensifiers, necessitating a medium-expansion system that does not currently exist.
Innovation Solution
A glass composition with a high refractive index and medium-expansion coefficient, comprising specific weight percentages of SiO2, Al2O3, B2O3, CaO, BaO, La2O3, Nb2O5, Ta2O5, Y2O3, ZnO, TiO2, and ZrO2, fabricated through a melting and annealing process, which matches the thermal expansion of Kovar alloy and provides excellent thermal stability and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high expansion system glass is used in fiber optic imaging elements, then the glass can be easily manufactured with existing materials, but the thermal expansion coefficient (87±5)×10−7/°C. is far from the sealing matching degree of Kovar alloy, leading to poor sealing stability and reduced service life
Solution Approach 1:
The patent changes the thermal expansion parameter of the glass by modifying its chemical composition. Specifically, it adjusts the ratios of network formers (SiO2, B2O3) and network modifiers (BaO, La2O3, Nb2O5) to achieve a thermal expansion coefficient of (68±5)×10−7/°C., which matches Kovar alloy. This parameter change resolves the contradiction between ease of manufacture and thermal expansion matching.
Solution Approach 2:
The patent creates a composite glass system combining multiple oxides (SiO2, B2O3, BaO, La2O3, Nb2O5, TiO2, ZnO, ZrO2) in specific proportions. This composite material approach allows precise control of thermal expansion properties while maintaining other required characteristics like refractive index and chemical stability, enabling matching with Kovar alloy for reliable sealing.
2Reliability
If the glass composition is modified to achieve medium-expansion coefficient matching Kovar alloy, then thermal stability and sealing performance are improved, but the refractive index and other optical properties must be precisely controlled
Solution Approach 1:
The patent systematically adjusts multiple compositional parameters simultaneously: SiO2 (5-9%), B2O3 (23-28%), BaO (6-12%), La2O3 (30-34%), Nb2O5 (4-8%), and other oxides. By coordinating changes in these parameters, it achieves the target thermal expansion coefficient while maintaining refractive index of 1.80-1.82 and other optical properties, resolving the contradiction between thermal stability and manufacturing precision.
3Illumination intensity
If the refractive index is increased to 1.80-1.82 for optimal optical performance, then light transmission efficiency and numerical aperture are improved, but the glass composition becomes more complex and difficult to manufacture
Solution Approach 1:
The patent employs a composite glass system with high La2O3 content (30-34%) combined with BaO (6-12%), Nb2O5 (4-8%), and other oxides. This composite formulation achieves the high refractive index of 1.80-1.82 required for optimal optical performance while providing a manufacturable composition through systematic ratio optimization, resolving the contradiction between optical performance and ease of manufacture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The glass with a medium-expansion coefficient of (68±5)×10−7/°C and high refractive index of 1.80-1.82 ensures perfect sealing and thermal stability, suitable for low-level-light image intensifiers, maintaining performance across varying environments and extending the service life of imaging devices.
Implementation Method 1
effective sealing and matching with Kovar alloy having a similar coefficient of linear thermal expansion (50×10−7/° C.) is required to improve the stability
Implementation Method 2
Glass with high refractive index for fiber optic imaging elements
Data Source
AI summary
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: SiO2 5-9%, Al2O3 0-1%, B2O3 23-28%, CaO 0-3%, BaO 6-12%, La2O3 30-34%, Nb2O5 4-8%, Ta2O5 0-1%, Y2O3 0-1%, ZnO 4-9%, TiO2 4-8%, ZrO2 4-6%, SnO2 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.