Hi Philippe,
My comments are interspersed below. Hope these help.
>Any lead where to talk and ask for these "toys" I know they
>are expensive...
Edmund Industrial Optics (http://www.edmundoptics.com) now carries UV
optics. Simple planoconvex and biconvex lenses are available for around USD
$100 each for 25mm diameter, and about USD $200 each for 50mm diameter.
(Maybe you could make satisfactory images with a single optic if the
wavelength range was narrow enough, and the aperture was slow enough.) I
used to buy most of my UV optics from a company called ESCO Products, Oak
Ridge, New Jersey (USA). They were about the best in terms of price. The
URL I have doesn't seem to be valid anymore, but I believe they're still in
business. They can be reached by telephone at (973) 697-3700.
>What kind of mirror should be used for UV purpose ?
Either uncoated aluminum, or MgF2-coated aluminum. The astronomical mirrors
are typically coated with SiO, which is not good in the UV. There are
companies that advertise in the back of Sky & Telescope that provide mirror
coating services and custom optics. Not sure if they could get you MgF2
coating, but they could certainly sell you an uncoated aluminum paraboloid
and matching secondary diagonal (flat) mirror. Shouldn't be more than maybe
$500 for an 8"-diameter f/6 paraboloidal mirror, quarter-wave surface
finish, and custom coating. Maybe another $100 for the diagonal, if it's
coated at the same time.
>I was thinking to filter UV before the pinhole, then maybe just
>one correcting lense, I don't really care about distortion at the
>moment ;-P
Sounds like that would work, provided you can find a good filter material.
Maybe just a quartz window with some multilayer dielectric? This is going
to cost you some money, however....
This all sounds very interesting. Good luck, and let me know how the film
works out.
Bill Peifer
Rochester, NY
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