Low-Oxygen Chalcogenide Glass for Infrared Sensor Transmittance
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Solution Overview
Problem
Chalcogenide glasses with high oxygen content exhibit decreased infrared transmittance, leading to poor sensitivity in infrared sensors, particularly for detecting infrared rays emitted from living bodies, and are difficult to process into complex shapes due to crystalline materials.
Innovation Solution
A method for producing chalcogenide glass with an oxygen content of 100 ppm or less by using a reducing gas during the melting process, specifically N2-H2 mixed gas, to minimize oxygen impurities and absorption peaks, and controlling the composition of Te, Se, Ge, Ga, and other components to enhance infrared transmittance and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crystalline materials (Ge, ZnSe) are used for optical elements, then infrared transmittance is good, but processability is poor and mass production is difficult
Solution Approach 1:
The patent changes the material phase from crystalline to vitreous by using chalcogenide glass compositions. This parameter change maintains the required infrared transmittance while significantly improving processability and enabling mass production of complex optical shapes.
Solution Approach 2:
The patent employs composite chalcogenide glass materials containing multiple elements (Ge, Ga, Sb, As, Te, Se, S, Ag, Si) in specific proportions. This composite approach achieves both good infrared transmittance and improved processability compared to pure crystalline materials.
2Ease of manufacture
If raw materials are melted in air, then melting process is simple, but oxygen mixes as impurity into the glass and binds to components, causing absorption peaks in infrared range
Solution Approach 1:
The patent employs a reducing gas atmosphere (N2-H2 mixed gas, CO, H2S, N2O, SO2, or NH3) during the melting process. This inert/reducing environment prevents oxygen from mixing into the glass while maintaining a relatively simple melting process, thereby preserving infrared transmittance.
Solution Approach 2:
The patent uses a reducing gas atmosphere that converts the potentially harmful effect of oxidation into a beneficial reduction process. The reducing gas removes oxygen impurities from the glass melt, transforming the melting process from one that introduces contaminants to one that purifies the material.
3Ease of manufacture
If oxygen content is high in chalcogenide glass, then manufacturing is easier, but infrared transmittance decreases significantly at wavelength of 10 μm or more
Solution Approach 1:
The patent uses a reducing gas atmosphere during melting to prevent oxygen contamination. This maintains manufacturing feasibility while achieving low oxygen content (100 ppm or less) that preserves infrared transmittance at wavelengths of 10 μm or more.
Solution Approach 2:
The patent precisely controls the oxygen content parameter to 100 ppm or less through the reducing atmosphere process. This parameter change enables the glass to maintain both manufacturability and high infrared transmittance in the critical wavelength range for detecting living bodies.
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 resulting chalcogenide glass exhibits excellent infrared transmittance and is suitable for use in infrared sensors, reducing image distortion and enabling mass production of optical elements with complex shapes.
Implementation Method 1
while a reducing gas is introduced into the quartz container, the quartz container is raised in temperature to 650 to 1000°C at a rate of 10 to 40°C/hour in a melting furnace
Implementation Method 2
the quartz container is raised in temperature to 650 to 1000°C at a rate of 10 to 40°C/hour in a melting furnace and then held for six to twelve hours
Data Source
Figure 1
AI summary
Provided is a glass having excellent infrared transmittance and being suitable for use in infrared sensors. A chalcogenide glass material has an oxygen content of 100 ppm or less.