|Smoke and Mirrors: Ultra-Rapid-Scan FT-IR
If the doubly wedged-disk is fabricated with a constant radius it will be
badly out of balance because of the extra mass on the thick side. The force generated by a
particular differential of angle can be expressed as a double integral. The balance
condition can then be found by setting the forces at opposite points on the disk equal.
Fixing the radius of the thin half of the disk to a constant 50 mm then leads to a shorter
and varying radius on the thick side. The radius only needs to vary by about 4 mm to
achieve a very good mechanical balance. Such a disk can be readily manufactured with a
numerically-controlled milling machine.