Re: Open (i think) design for a parallel robot (reprap ma

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Carl Mikkelsen
<c.mikkelsen@...> wrote:

>
>...
> What I was curious about is how to measure the small-scale

deviations from

> the desired shape. Isn't this property called surface roughness?

What is

> a simple way to measure surface roughness?
>

A weird thought, entirely unproven, is to light the surface from a
small angle, say 5 to 10 degrees. Then take a digital picture. Then
measure the amount of high frequency component in the photograph
(using a 2-d fast fourier transform). It requires some complex
software, but the gadgets are pretty cheap.

The notion is that the rougher the surface, the more dark-light
jitter, so the more high-frequency components.