Undamaged measurement of the sub-micron diaphragm and gap by tri-beam interference


A simple, high-accuracy and non-destructive method for the measurement of diaphragm thickness and microgap width based on modulated tri-beam interference is demonstrated. With this method, a theoretical estimation error less than 0.5% for a diaphragm thickness of ~1 μm is achievable. Several fiber-tip air bubbles with different diaphragm thicknesses (6.25, 5.0, 2.5 and 1.25 μm) were fabricated to verify our proposed measurement method. Furthermore, an improved technique was introduced by immersing the measured object into a liquid environment to simplify a four-beam interference into tri-beam one. By applying this improved technique, the diaphragm thickness of a fabricated in-fiber rectangular air bubble is measured to be about 1.47 μm, and the averaged microgap width of a standard silica capillary is measured to be about 10.07 μm, giving a corresponding measurement error only 1.27% compared with actual scanning electron microscope (SEM) results.

Publication DOI: https://doi.org/10.1109/JLT.2019.2940502
Divisions: College of Engineering & Physical Sciences > School of Informatics and Digital Engineering > Electrical and Electronic Engineering
College of Engineering & Physical Sciences > Aston Institute of Photonics Technology (AIPT)
College of Engineering & Physical Sciences
Additional Information: © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Publication ISSN: 1558-2213
Full Text Link:
Related URLs: https://ieeexpl ... cument/8828084/ (Publisher URL)
PURE Output Type: Article
Published Date: 2019-12-01
Published Online Date: 2019-09-10
Accepted Date: 2019-09-04
Authors: Chen, Yanping
Liu, Shen
Sun, Zhongyuan
Zhang, Lin (ORCID Profile 0000-0002-1691-5577)
Sahoo, Namita
Luo, Junxian
Zhao, Yuanyuan
Liao, Changrui
Du, Bin
Li, Chi
Wang, Yiping



Version: Accepted Version

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