Re Edmund Scientific 3D device

[edsap@xxxxxxxxxxxxxxxxx (Peter Homer)]

I have one of the devices that Euni Gi Paek refers to and looking at my
copy of the Edmund scientific catalogue it seems identical to that one.
Although I bought mine from a mail order catalogue here in Britain. The
diagram in the catalogue shows double concave mirrors which mine certainly
has rather than parabolic although I should think they would work as well.
The object is at the focal point of the lower mirror so is projected
upwards to the second one overturned over the lower one and refocussed at
its focal point . Because there is a hole cut in it the object actualy
forms an aerial image above it.
 With mine I find the effect is not as good as it could possibly be because
the mirrors are not the highest quality ,although they warn to be very
carefull cleaning dust etc off they are not first surface mirrors but I
think are self coloured silver plastic.  The size of object you can put in
is very limited not only by the diameter of the hole but also in height .
I suspect you could make your own from two of the mirrors used in torches
spotlamps etc taped together mouth to mouth it should not matter about the
lower hole provided the object covered or protruded through it sufficiently
to be at the focuss. You could then place it over objects without having to
open the mirrors.
                                     P.J.Homer



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