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Erratum published on 14 May 2016, see Sensors 2016, 16(5), 698.

Open AccessArticle
Sensors 2015, 15(4), 8512-8526; doi:10.3390/s150408512

Development and Beam-Shape Analysis of an Integrated Fiber-Optic Confocal Probe for High-Precision Central Thickness Measurement of Small-Radius Lenses

1
School of Electronic Engineering, Institute of Engineering, Suranaree University of Technology, 111 University Ave., Muang, Nakhon Ratchasima 30000, Thailand
2
Photonics Technology Laboratory, National Electronics and Computer Technology Center (NECTEC), National Science and Technology Development Agency (NSTDA), 112 Thailand Science Park, Pahol Yothin Rd., Klong Luang, Pathumthani 12120, Thailand
*
Author to whom correspondence should be addressed.
Academic Editor: Gary R. Pickrell
Received: 14 January 2015 / Revised: 5 April 2015 / Accepted: 7 April 2015 / Published: 13 April 2015
(This article belongs to the Special Issue Optical Sensors for Chemical, Biological and Industrial Applications)
View Full-Text   |   Download PDF [610 KB, uploaded 14 May 2016]   |  

Abstract

This work describes a new design of a fiber-optic confocal probe suitable for measuring the central thicknesses of small-radius optical lenses or similar objects. The proposed confocal probe utilizes an integrated camera that functions as a shape-encoded position-sensing device. The confocal signal for thickness measurement and beam-shape data for off-axis measurement can be simultaneously acquired using the proposed probe. Placing the probe’s focal point off-center relative to a sample’s vertex produces a non-circular image at the camera’s image plane that closely resembles an ellipse for small displacements. We were able to precisely position the confocal probe’s focal point relative to the vertex point of a ball lens with a radius of 2.5 mm, with a lateral resolution of 1.2 µm. The reflected beam shape based on partial blocking by an aperture was analyzed and verified experimentally. The proposed confocal probe offers a low-cost, high-precision technique, an alternative to a high-cost three-dimensional surface profiler, for tight quality control of small optical lenses during the manufacturing process. View Full-Text
Keywords: fiber-optic confocal microscopy; non-contact thickness measurement; ball lenses; optical metrology fiber-optic confocal microscopy; non-contact thickness measurement; ball lenses; optical metrology
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Sutapun, B.; Somboonkaew, A.; Amarit, R.; Chanhorm, S. Development and Beam-Shape Analysis of an Integrated Fiber-Optic Confocal Probe for High-Precision Central Thickness Measurement of Small-Radius Lenses. Sensors 2015, 15, 8512-8526.

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