High-Temperature Sapphire Window
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Thermal Shock Resistant Sapphire Viewport | Furnace & Flame Monitoring Optical Window Felix Glass supplies custom high-temperature sapphire windows and viewports for industrial furnaces, flame detectors, high-heat process monitoring, plasma chambers and high-temperature sensor systems. Single-crystal sapphire retains outstanding mechanical strength and optical transmission at elevated temperatures, with superior thermal shock resistance compared to many other optical substrates. AR coatings are optional for target wavelength bands. High Temp Sapphire Window | Furnace Viewport Single-crystal sapphire (Al₂O₃) is the preferred optical substrate for high-temperature viewport applications. It maintains stable performance up to 1700°C, features low thermal expansion, excellent thermal shock resistance, high hardness and chemical inertness. It transmits UV, visible and near/mid-wave infrared up to ~5μm. Compared with fused silica, sapphire offers much higher maximum service temperature and better abrasion resistance. Material substrate does not equal final performance grade. Specify continuous operating temperature, thermal cycling requirements and wavelength for accurate quotation. Interferometer Inspection Precision Polishing Finished Sapphire Viewport All high-temperature sapphire windows are inspected for surface figure, transmission and scratch-dig quality. Thermal cycling validation is available for critical furnace and flame-monitoring applications. Standard AR coatings boost transmission for visible, NIR or MWIR bands. For high-temperature cycling environments, we apply high-temperature stable AR coatings formulated to resist peeling and shift under heat cycles. Avoid standard low-temperature coatings for furnace service. Learn more about optical coating technology. To generate an accurate quotation within 24 hours, please prepare below information: Sapphire can sustain ~1700°C continuously, higher than fused silica. Sapphire also has better abrasion and thermal shock performance, while fused silica is lower cost for moderate temperature use. No. Sapphire transmission cuts off near 5μm. For 8–14μm LWIR pyrometry or thermal cameras, CVD ZnS is the correct substrate. Yes. We custom machine steps, counterbores and sealing grooves to match your gasket and furnace housing design, with full post-machining optical polishing.
High-Temperature Sapphire Window Manufacturer
OEM Custom Machining | AR Coating | High Thermal Shock ResistanceMaterial & Grade Overview
Key Specifications & Custom Options
Substrate Material
Single Crystal Sapphire (Al₂O₃)
Shape
Round window, square / rectangular viewport, plate, disc, custom profile
Size Range
Dia 5mm‑300mm, custom thickness, step edge, counterbore & sealing groove
Surface Quality
20‑10 /40‑20 scratch‑dig, customized per customer drawing
Working Wavelength Band
0.2–5.0μm, UV / Vis / NIR / MWIR broadband transmission
Coating Options
Uncoated, UV AR, VIS-NIR AR, MWIR AR, high-temperature resistant AR coating
Custom Machining
Chamfer, drilling, counterbore, sealing groove, stepped edge, edge polishing
Inspection
Interferometer, spectrophotometer, thermal cycling test optional, material certificate available
Manufacturing & Inspection Evidence
Typical Application
Coating Selection Guide
Order & Quotation Requirements (Valid RFQ Checklist)
Send Drawing For Quote
FAQ Snippets
Sapphire vs fused silica for high temperature viewports?
Can high-temperature sapphire window be used for 8–14μm thermal imaging?
Can you machine sealing grooves and counterbores for furnace gaskets?
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