3D surface profile measurement of unsymmetrical microstructure using Fizeau interferometric microscope

Shih Wei Yang*, Chern Sheng Lin, Shir-Kuan Lin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


In this paper, an automatic optical inspection system for the 3D surface profile of an unsymmetrical microstructure using Fizeau interferometer was proposed. This non-contact optical inspection system is suitable for measuring the lens sag and 3D surface profile of symmetrical and unsymmetrical microlenses. Referring to the unsymmetrical microlenses as an example, the distribution of the interference fringes is partly dense and partly rare, and is completely different from the equally dense distribution of symmetrical microlenses. Thus, a novel algorithm is proposed to solve the above mentioned problem in this paper, namely, individually determining the darkest points of the dark fringes and the brightest points of the bright fringes, and fitting these discrete points as close curves through the Bezier curve theory. As the contour lines of an unsymmetrical microlens are obtained, the 3D surface profile of the unsymmetrical microlens can be plotted correspondingly. Furthermore, the proposed system has the following advantages due to its non-contact structure. This system is specifically designed for in-line measurements according to the rapid inspection speed; it has no need to coat a reflective layer on the inspected microstructure, thus avoiding damaging the surface structure of the sample.

Original languageEnglish
Pages (from-to)348-357
Number of pages10
JournalOptics and Lasers in Engineering
Issue number4
StatePublished - 1 Apr 2013


  • 3D surface profile
  • Bezier curve
  • Fizeau interferometer
  • Unsymmetrical microstructure

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