Question

Which of the following is not true for comparison method used for calibration of polygons?

(a) Identical polygons are used

(b) Polygons are mounted one above the other

(c) Polygons are mounted on the fixed table

(d) Reflecting faces of both the polygons are viewed simultaneously

The question was posed to me in unit test.

I'm obligated to ask this question of Calibration of Polygons in division Angular Measurement and Circular Division of Engineering Metrology

Answer 1

The correct answer is (c) Polygons are mounted on the fixed table

To elaborate: Two identical polygons are mounted one above the other on a table which can rotate. The autocollimator is placed in a position that it views simultaneously the reflecting faces of both the polygon.