Question

What is the position of straightness interferometer in straightness measurement optics?

(a) Before laser head

(b) After straightness reflector

(c) Between laser head and straightness reflector

(d) No need of interferometer

I got this question in an internship interview.

This interesting question is from Straightness topic in portion Straightness, Flatness, Squareness, Parallelism, Circularity and Rotation of Engineering Metrology

Answer 1

Correct option is (c) Between laser head and straightness reflector

The best I can explain: Straightness interferometer is placed between laser head and reflector. Beam from the laser passes through the interferometer which splits it into two beams which diverge at an angle and are directed to the reflector. The beams are then reflected from the reflector and return to the interferometer along a new path.