Ultra smooth surface has a roughness less than 1nm. We can achieve a roughness of 0.1nm with the substrate of fused silica, silicon, etc. Key features: - Low loss - low scatter Applications: - Soft X ray optical system - Mirrors for ring laser gyroscope (RLG) - High density wavelength division multiplexer - High energy laser mirror - Functional photoelectric device - Optical window - Polishing Magnetic Head