Telescope Mirror Making – The Backbone
Of Your Telescope
You want to build your own Telescope for home use, and then
you will definitely need to fabricate your own mirrors.
Dependents on making your own mirror would be the size, design
and complexity of the telescope you want as your end product.
A Newtonian Reflector is considered the most common telescope
built by amateurs and is a good starting project. Plans on telescope
mirror making are widely available.
Telescope mirror making needs careful ‘calibrating’,
or testing. Before you get to this stage, you need to grind,
polish and your glass needs to be ground and polished to a very
accurate point using a series of tools which should be similar
in size to the glass, using a series of finer abrasives. You
will also need a polishing pitch lap.
Construction
You have to test your Mirrors the shape of your mirror. A common
method to use would be Foucault Tester, simple to fabricate,
consisting of a light bulb, a piece of tin foil punched in the
centre with a pinhole and a razor blade.
Set up the Focault Tester close to mirror's radius of curvature.
The tester is adjusted so that the knife-edge interrupts the
returning beam from the pinhole light source. Viewing the mirror
from behind the knife-edge shows a pattern on the mirror surface.
If the mirror surface is a perfect spheroid, the mirror appears
evenly lighted across the entire surface. If the surface is
paraboloidal, the mirror looks like a donut or lozenge. It is
possible to calculate how closely the mirror surface resembles
a perfect paraboloid by placing a special mask over the mirror
and taking a series of measurements with the tester. This data
is then reduced and graphed against an ideal
While this is a very sketchy article on telescope mirror making,
it is best to keep in mind the following matters. The difficulty
in telescope mirror making is in the construction and should
be a very important factor in how you choose your project. Keep
in mind that in each design the difficulty of construction grows
as the ‘square of the diameter grows’. Simply, A
4 inch Newtonian telescope is considered fairly ‘easy’,
whereas a 6 inch Mirror is a good size since construction is
considered ‘not difficult’. But, a 12 inch would
be ‘difficult’ while anything approaching or exceeding
1m would usually be tackled by small groups.
It goes without saying that the large telescope mirror can
only be constructed by a myriad of Engineers in a location designed
for it.
A very good source of information on telescope mirror making
is the online library. You cannot only find all the information
on Telescope Mirror Making in deeper details.
Either way, telescope mirror making is generally cheaper to
make than it would be to buy commercially.
