Low Scatter Molybdenum Surfaces

Abstract

Molybdenum (Mo) mirrors are being used in many high power infrared lasers and are also candidates for lasers operating in the visible and ultraviolet spectral regions. However, a limiting factor is the scattered light from the mirror surface which adversely affects the operation of the laser and can prevent the laser from operating at all. It has previously been shown1 that the surface finish obtainable on Mo mirrors is directly related to the grain structure of the material. Profile roughnesses in the 40 - 60 Å rms range are generally measured for well polished Mo surfaces, although total integrated scattering (TIS) measurements2 yield effective roughnesses in the 15 - 25 Å rms range for these same surfaces. (The difference between these two roughness measurements is caused by the different range of spatial wavelengths, and will be discussed later in this abstract.)