BOULDER, Colo., June 6, 2011 — New superpolished laser mirrors from REO offer low loss, making them suitable for use in demanding applications. Microroughness is <0.5 Å, allowing them to achieve scattering loss of <5 ppm and finesse of 200,000 when incorporated into optical cavities. Ion beam-sputtered coatings are used to take advantage of the ultrasmooth surfaces and deliver reflectivities of >99.998% at any wavelength in the 450-nm to 2-µm range. The mirrors can be produced on a number of substrate materials, including BK7, fused silica, Zerodur, ULE, sapphire and silicon. They are supplied with diameters in the 6- to 101-mm range, with a flatness of λ/20 at 633 nm, 10-5 surface quality over an 80% clear aperture, with zero defects (0-0) achievable over controlled subapertures. Standard solvent-based cleaning methods maintain the low-loss specification. Mirrors with plano, concave and convex surface shapes are available. The company uses a suite of advanced metrology instrumentation to maintain and verify these performance specifications, including phase-shifting interference microscopy, cavity ringdown measurements and photothermal common path interferometers. The superpolished mirrors are useful in any laser or laser-based system that requires high reflectivity or low loss. Typical applications include cavity mirrors in low-gain gas and solid-state HeNe and HeCd lasers, and systems that use nonlinear processes. Other uses are in ring laser gyroscopes, instruments based on cavity ringdown spectroscopy and frequency reference standards.