Question

Which type of visual scale line setting against an index is widely used in sophisticated machines?

(a) Simple superposition type

(b) Alignment of vernier setting

(c) Symmetrical forming between two index marks

(d) Asymmetrical forming between index marks

I got this question during an interview.

The origin of the question is Scales and Gratings topic in division Measurement by Light-Wave Interference of Engineering Metrology

Answer 1

Right answer is (c) Symmetrical forming between two index marks

Best explanation: Index mark is utilized by all scale readouts, with reference to which reading of scale is noted. Symmetrical forming between two index marks is the type which is mostly used in sophisticated machines due to high setting precision.