Major Gage has listed a new, low-cost Profilometer that sells for 50% of products from the big guys.

 

Profilometers:

Profilometry is a technique used to extract topographical data from the surface of a part. The data can consist of a single point, a line scan, or even a full 3D areal scan. The purpose of profilometry is to get surface morphology, step heights, and/or surface roughness.

A profilometer is a measuring instrument used to record surface profile, in order to quantify its roughness. Critical dimensions as step, curvature, flatness are computed from the surface topography.  Profilometers are also known as “Surface Roughness Testers” or “Surface Finish Gauges” and can measure the micro-irregularities (roughness) of a given material.

Profilometers can be of the contact, or “tactile” variety (typically a diamond stylus) or optical-based, non-contact (e.g.: a white light interferometer or scanning confocal microscope).  Tactile, or contact profilometers have the advantage of being resistant to part contamination from RP, oil, or fluids.

Wikipedia has an excellent page about measuring roughness and surface finish.