Question

What is correct for the angle of autocollimators used for calibration of polygons?

(a) Angle between autocollimators is equal to the nominal angle between adjacent faces

(b) Angle between autocollimators is more than the nominal angle between adjacent faces

(c) Angle between autocollimators is less than the nominal angle between adjacent faces

(d) Angle between autocollimators is more or less to the nominal angle between adjacent faces

The question was asked in an international level competition.

This intriguing question originated from Calibration of Polygons in chapter Angular Measurement and Circular Division of Engineering Metrology

Answer 1

Right answer is (a) Angle between autocollimators is equal to the nominal angle between adjacent faces

Easy explanation: The angle between autocollimators are set such that the angle is equal to the nominal angle between adjacent faces of the polygon, it is to give reflections from adjacent faces of the polygon.