ATM Ronchi gratings (was: Parabolizing)

[Hugues_Laroche@aia.com]

Bob wrote:

>Last question, where can I get a Ronchi grating to do a Ronchi test?
There is no harm in asking questions, that's the way things progress.
Regarding Ronchi grating, I got one for few French Francs, so around
$1.5 fom my ATM supplier. But I also generated some myself in PostScript,
printing on transparencies. Do you wish that I dig in my stuff and
send you some? I am not absolutely sure of the quality of those I make,
but I feel relaxed because superpimposing 2 of them parallel or with
an angle shows nice straight and regular "Moir?" figures. And I can make
some up to an A4 (21.x29.7 cm) size! The only delicate thing is
select the # of lines/inch which is not completely free once going near the
resolution limit on a PS printer.

Hope it helps,

Hugues