From: hermit 
To: Russell Jocoy 
CC: atm{at}shore.net
Reply-To: hermit 


Russell Jocoy wrote:
>
>     ("atm{at}shore.net")
>
>          Hello all, I am in the process of making a Foucault / Ronchi
> tester.  I have a Question about
> the knife edge on the Foucault test. Does the knife edge have to come in
> from the side ? or can
> the blade "sweep" in like a clock hand.  I am asking because
, if I can
> sweep the blade into the light
> I can have a single pivot point.
>       I am using a penlite for my light source with a diffuser in front, but
> this seems too bright. It may
> be the penlite has a small lens in front of the bulb.
>      I also mounted a viewing mirror next to the light source so I don't
> have to view from behind and
> can view from the side. Would there be any problems with this? I know that
> all my zones would be
> on opposite sides from what is viewed but I is so much easier to view from
> the side.


Make it as long a pivot as possible.  The problem will be in having it
close to vertical when you get the shawdows.

Ken

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