FW: [ATM] make ronchi grating

[tstokes at pacbell.net (Tom Stokes)]

Hasn't anyone created a (Windows) program to draw Ronchi lines on
transparent film using a standard PCL printer? Most printers have
have a resolution of at least 600 dpi which should be plenty.

Tom Stokes
http://home.pacbell.net/tstokes features my mirror grinding machine.

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I made my own Ronchi grating from the postscript code, it worked great. I used 
100 lpi since it was a simple multiple of my printer's resolution. I printed 
two pieces out onto transparency "paper." I cut one out for the Foucault 
tester, and cut the other out to fit inside the cap of a film can. That goes 
onto a film can with the bottom cut out. That gives me a Ronchi grating I can 
pop into a focuser to use on a fully assembled scope.
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