Re: Home-brew beam splitter question.

[P3D Brian Reynolds <reynolds@xxxxxxxxx>]

Bill Costa wrote:
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>     My question is, does the plate have to be a `half silvered' mirror, or
>     is an ordinary sheet of plate glass sufficient?  (I realize that for
>     best results a black box surrounding the glass/camera lens would be
>     needed as well, etc. etc.)  Of course if a half silvered mirror is
>     needed my next question will be, does anyone know of a good source for
>     the appropriate type.  :-)  Thanks in advance....
> 

This can work (assuming the alignment is good and unwanted reflections
are taken care of), but the two cameras will not receive the same
amount of light (because clear glass transmits more to Camera A than
it reflects to Camera B), so Camera B will have to have a much longer
exposure.  If you use a half silvered mirror (by which I mean a mirror
that reflects 50% of the incident light and transmits 50% of the
incident light) the exposure settings for both cameras will be the
same.  I think Edmund Scientific <URL:http://www.edsci.com/> sells the
mirror you want (possibly even in a mount for an optical bench if you
want to spend that much), and you may be able to find something
(probably cheaper) at Surplus Shack <URL:http://www.surplusshack.com/>
or American Science & Surplus <URL:http://www.sciplus.com//>.  If
you're feeling adventurous, The Amateur Telescope Makers' Web Page
<URL:http://www.tiac.net/users/atm/> should get you pointed in the
right direction for making your own mirrors.

-- 
Brian Reynolds     | "Knowledge, Sir, should be free to all!"
reynolds@xxxxxxxxx |  -- Harcourt Fenton Mudd
NAR# 54438         |     "I, Mudd"


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