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.