Re: [ATM] Phase contrast and the 10 incher.

[Dominic-Luc Webb <dlwebb@canit.se>]

On Wed, 25 Apr 2007, Arjan te Marvelde wrote:

> Hello Dominic,
>
> > either passes right through, or reflects back towards to the
> > detector, perhaps striking any defects within the glass a second
> > time.
>
> This would mean that the back and front surface have to be parallel, which
> is normaly only true in the center. Further outward, the light is reflected
> away from the optical axis, the curvature of the front surface does not
> refract the light back to source. Hence I think that in most cases you will
> really only see light scattered by subsurface (or backsurface)
> imperfections.
> On further thought, I think this scatter may become more obvious if you
> don't use a slit source, but a single KE moving source setup.
>
>    Arjan

I think we are in agreement with the proviso that it is possible
to see the back surface, as with a ronchi grating. I am in the
process of getting my tester back up and running. I will think on
some KE images of some glass I have with artefacts of known origins
at known positions in the glass.

Dominic

_______________________________________________
ATM mailing list http://www.atmlist.net/