Surface exhibiting movement of fringes towards centre - Metrology & Quality Control

Q.  Which type of surface in a fringe pattern exhibits the movement of fringes towards the centre?
- Published on 07 Aug 15

a. concave surface
b. convex surface

ANSWER: concave surface


  • Sravanthi   -Posted on 26 Oct 15
    - Different fringe patterns of a surface are obtained depending upon the surfaces in contact, when an optical flat is used to measure flatness of a surface.

    - When a concave surface is tested by using an optical flat, the fringes obtained move towards the centre.

    - The fringes move away from the centre, if the surface is convex.

    - Different fringe patterns such as conical, spheroid, ridge, valley, cylinder, perfectly flat etc, are obtained depending upon the surface being tested.

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