u/CreEngineer

Dear optics wizards,

I am facing a problem with surfaces on some calibration artefacts for calibration laser triangulation. For getting exact measurements in calibration we need a perfectly flat surface with a nice diffuse reflection. Mirror finish/specular reflection does not work for standard sensors. Glass bead blasting or trovalizing the surface does introduce more laser speckle.

What I know was tried so far:
Sputtering: does work but does not change the surface roughness and makes the laser "bloom" a bit. Was tried on aluminum and glass.

Paint: nice diffuse reflection but does introduce variance in coating thickness, especially on corners (roundover)

Ceramic: ceramic gauge block was more on the shiny side and also showed blooming

Any ideas what combination of base material and coating could work for this application?

I work in development for optomechanical precision equipment. In this field there are some alloys that are regarded "the ones to use" because they do not deform over time. The two most used are 6262A (for round stock) and 5083 C250 Elox Plus (plate).

But this is just a word-of-mouth thing, or "we did intensive testing", but no one ever could show me any evidence or a white paper about this topic. It also not clear what mechanism exactly is responsible for deformation, is it internal stresses from manufacturing or any other treatments like T6 or something completely different.

What experience do machinists have with such requirements? Is there any further information on this topic you know of? What materials would you recommend with these properties.