Uncoated solid Molybdenum (“Moly”) mirrors are simply the toughest, most durable, longest lasting laser mirrors available. Molybdenum has the lowest thermal expansion of any commercially used metal, and will withstand extreme temperatures without significantly expanding or softening. It has a Melting Point of 2,623 °C (4,753 °F).
For infra red uses, polished uncoated Molybdenum has a high natural broad band reflectivity, approx 98%.
Molybdenum mirrors need no coating; the extremely hard surface resists weld spatter, fumes, smoke and process debris. Molybdenum mirrors can be scrubbed with brushes, soak cleaned in organic solvents or detergents repeatedly.
Solid molybdenum mirrors are used in high power CO2 laser welding, where debris and back spatter would destroy other mirrors, and in TEA lasers where the high pulse energies can cause localized melting on the face through laser damage.
In laser cutting the final mirror of the delivery system is often upgraded to a Molybdenum one, as this is the most exposed, and therefore most frequently damaged mirror.
It’s not just high power CO2 lasers that can benefit from Molybdenum mirrors, Er:YAG lasers, especially surgical and dental laser systems, Quantum Cascade Lasers (QCL) for gas sensing and spectroscopy, in fact any infrared application that needs durable, tough, and chemically resistant mirrors benefit from using solid molybdenum reflectors.