Gold coating offers a broad and consistent reflectivity in the infra red spectrum from 800nm to far beyond 20 microns. FLIR systems, and thermal imaging in the long wavelength infrared use metal mirrors.
Gold coated copper mirrors have found uses at 100um micron wavelengths e.g far infrared lasers such as Methanol lasers.
Electroplated Gold mirror coating is ideal for broad spectrum IR applications such as infrared gas spectroscopy, or where multi-wavelength infrared sources are used.
Terahertz imaging, and Terahertz spectroscopy both use Gold coated mirrors for directing and collecting sub millimeter wavelength radiation.
Infra red sources such as Optical Parametric Oscillators, Lead Salt laser diodes, are an area of research where gold coated mirrors can be used for multiple wavelength reflection.
The chemical inertness of gold finds uses in environmental monitoring of gases such as in chimneys, flues, pipes, and of liquids where other coating materials would be destroyed.
Laser Beam Products polish Stainless steel mirrors for use in the brewing, nuclear, and food industries, applications where stainless steel is one of the few approved materials for use in production equipment.