What is the surfaces fineness of a mirror finish in rms?

A mirror finish is characterized by an extremely smooth surface that reflects light very well, which is typically measured in terms of surface roughness. The root mean square (RMS) roughness value that corresponds to a mirror finish is generally around 1 micrometer or less. This level of smoothness meets the standards for a mirror finish because it allows for minimal light scattering, resulting in a highly reflective surface.

The other ranges mentioned do not fit the definition of a mirror finish. For instance, values of 2 to 8 or 2 to 5 micrometers would indicate a surface that is still relatively rough compared to a true mirror finish, leading to less effective light reflection. Similarly, the range of 1 to 3 micrometers would encompass finishes that are not as polished and reflective as a true mirror finish. Therefore, the specified RMS value of around 1 micrometer accurately represents the quality and characteristics of a mirror finish.