Re: [ATM] Ain't got no shperometer

["Arjan te Marvelde" <Arjan.te.Marvelde@hetnet.nl>]

Even simpler than a KE tester is a Ronchi setup: no platform needed.

You either buy or make a grating, stick it onto some diffused lightsource 
and hold it somewhere near COC.
Grating you can make with a laser printer and an overhead-projector slide 
(do they still exist?)
Diffused light source you can make with a cut-off and fine ground jumbo LED.

IIRC, Bob May once mentioned such a 'pocket' ronchi tester.

   Arjan

>> Foucault tester is one of the simplest things to build.
>> You should have one.
>
> You're not wrong.
>
>> You need only one Led, knife and movable stand.
>
> Well, yeah ... but that movable stand can get to be kind of
> elaborate.  I'm not going to go crazy on it, but I'd like it to be
> reasonably precise.
>
> Haven't given it that much thought, though.  Maybe something
> ultra-simple, just for the time being, would be worth it.

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