Chalcogenide glasses (families such as Ge–As–Se and Ge–Sb–Se, among others) exist because IR lens designers wanted glass-like processing with crystal-like IR transmission. For MWIR/LWIR consumer and commercial thermal cameras, molded chalcogenide aspheres can collapse cost curves that crystalline diamond-turning cannot match at volume.
Design space
Transmission typically opens in the SWIR and extends through MWIR into LWIR depending on composition and thickness. Index is high relative to oxide glasses, enabling compact prescriptions. Dispersion and dn/dT differ sharply from Ge or ZnSe — do not drop-in replace a Ge singlet with a chalcogenide blank of the same radii and expect MTF to hold.
Manufacturing path
Precision glass molding of aspheres is the economic story. That implies tooling investment, process windows and coating recipes qualified on the glass family. For lower volumes, diamond-turned crystalline solutions may still win schedule. RFQs should state annual volume honestly.
Reliability notes
Some compositions are softer and more chemically sensitive; coating adhesion and environmental seals matter for outdoor cameras. Always qualify humidity, thermal shock and cleaning chemistry on the finished coated lens, not on the bare blank datasheet alone.
If your roadmap includes high-volume thermal imaging optics, discuss chalcogenide early — tooling lead time dominates. Start with the Spectral Explorer and a volume-honest RFQ.