Re: Re[2]: ATM 8" f3.8 -- Worthy project?

["Richard" <richas@idt.net>]

Here is a radical idea not found in authoritative books....
what if, instead of a wire, you use a small spherical bead?
Then you get the circular shadow, but not the vertical bar
shadow.   The bead can be moved from side to side to allow
testing of tilted or astigmatic surfaces.   Hmmm.....

And if you replace the bead with a pinhole (the pinhole is
an inverse bead), I guess you see an illuminated circle.
Hmmm....

And if you use a slit, I guess you see an illuminated circle
with a vertical illuminated bar....  Hmmm....

Please keep this idea secret, as it is not according to
established orthodox dogma.

. . . Richard

----- Original Message -----
From: <Hugues_Laroche@ses-astra.com>
To: "Dwight Elvey" <elvey@hal.com>
Cc: <atm@shore.net>
Sent: Thursday, October 26, 2000 11:27 PM
Subject: Re: Re[2]: ATM 8" f3.8 -- Worthy project?


>
>
>
> Hi Dwight,
>
> >as was mentioned, you can use a slit but you need a way
to
> >adjust them parallel. This makes a moving source a good
>
> What about having the wire being both the source and the
wire?
> By lighting it transversaly by a laser (well I agree it
looks
> uncomfortable to have a laser beam cross-passing at a few
mm of your
> eye) or a fiber optic like they do for the mini-maglite?
>
> Hugues
>
>
>
>
>