Product Overview
Germanium is the workhorse of thermal imaging: with refractive index near 4.0 it bends long-wave infrared strongly with few surfaces, transmitting from roughly 2 to 14 µm to cover both the 3–5 and 8–12 µm atmospheric windows used by thermal cameras and CO2 lasers. Its properties come with two hard constraints buyers should design around. First, bare germanium reflects over 50% per surface, so AR coating is mandatory — broadband stacks for the 3–5 or 8–12 µm bands, or diamond-like carbon where sand, rain and abrasion demand it. Second, germanium is thermally fragile optically: transmission degrades progressively as temperature rises, and sustained service above about 100°C requires either design compensation or a different material — a real limit in engine-adjacent or enclosed-camera duty. Manufacturers listed here grind spherical germanium lenses and diamond-turn aspherics for compact thermal objectives, coating in-house with transmission spectra supplied per lot.
OEM & Customization Capabilities
- Band-Specific AR – 3–5, 8–12 or dual-band coatings with FTIR transmission reports.
- DLC Option – abrasion-resistant front elements for outdoor and automotive duty.
- Aspheric Turning – SPDT aspherics reducing element count in compact thermal objectives.
Industry Applications
- Optical Lenses
- Thermal Imaging & IR