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Re: [ATM] Ronchi rulings

If you have an old, dead inkjet printer to take apart, you're likely to 
find a mylar linear optical grating ribbon that makes several dozen very 
good quality 150 LPI (or so) gratings.
In recent HP Inkjet printers, it's stretched along one of the upper 
steel rods that the printhead assembly rides on.

To make one for your scope, cut a square (approx 1/2 Cm) piece of ribbon 
and glue across a hole in a 35mm film can lid, then cut the bottom out 
of the can and attach the lid assembly. Use it like a 1 1/4" eyepiece on 
a bright star for a full optical system test.

The grating is very high contrast - much better than a normal film negative.

         Bill Prewitt

***** Webpage of telescope making and caving *****
             www.astrocaver.com
**************************************************

Michael Lindner wrote:
> On Tue September 13 2005 2:08 pm, Rick M wrote:
> 
>>   Can someone please tell me where I can purchase a
>>ronchi ruling or screen
> 
> 
> I believe Willmann-Bell http://www.willbell.com/ sells them. You can also make 
> your own several ways.
> 
> http://astro.umsystem.edu/atm/ARCHIVES/JUN97/msg00266.html
> http://www.geocities.com/CapeCanaveral/9601/ronchi.htm
> 
> clear skies

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