The Foucault Tester
Making a 4.25 Inch Dobsonian
Reflector Telescope
Below are some photos of the
Foucault tester I built.
This is a side view of the
tester.
Having the adjustment bolt
in the front was at times a little inconvenent.
This picture shows the
tester bed.
The cross pieces are to keep
the movement perpendicular.
I used furniture wax to
lubricate the movement.
Note the to bolts, one for
lateral movement and the other
to push the knife edge back
and forth.
This picture shows the
location of the LED behind the two rasors.
The small black box is just
a battery case.
This is an overhead view
showing the movement scale.
The scale was made printed
on a 600dpi laser scanner.
This is a simple stand I built
to hold and adjust the mirror during testing.
Having something like this
is more valuable than one might ordinarily think.