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Development of a laser based inspection system for surface defect detection

Bhuian, Mohammed Belal Hossain (2002) Development of a laser based inspection system for surface defect detection. Master of Engineering thesis, Dublin City University.

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The objective of this project was to design and develop a laser based inspection system for the detection of surface defects and to assess its potentiality for high-speed online applications. The basic components of this inspection system are a laser diode module as illumination source, a random access CMOS camera as detector unit, and an XYZ translation stage. Algorithms were developed to analyze the data obtained from the scanning of different sample surfaces. The inspection system was based on optical triangulation principle. The laser beam was incident obliquely to the sample surface. Differences in surface height were then detected as a horizontal shift of the laser spot on the sample surface. This enabled height measurements to be taken, as per the triangulation method. The developed inspection system was first calibrated in order to obtain a conversion factor that would render a relationship between the measured spot shift on the sensor and the vertical displacement of the surface. Experiments were carried out on different sample material surfaces: brass, aluminum <ind stainless steel. The developed system is able to accurately generate three-dimensional topographic maps of the defects presented to it in this work. A spatial resolution of approximately 70 pm and a depth resolution of 60 pm were achieved. Characterization o f the inspection system was also performed by measuring the accuracy of distance measurements.

Item Type:Thesis (Master of Engineering)
Date of Award:2002
Supervisor(s):El Baradie, M.A. and Brabazon, Dermot
Uncontrolled Keywords:Metallurgy; surface defects; topographic maps
Subjects:Engineering > Materials
Engineering > Mechanical engineering
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Engineering and Computing > School of Mechanical and Manufacturing Engineering
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License
ID Code:17361
Deposited On:31 Aug 2012 12:01 by Fran Callaghan. Last Modified 31 Aug 2012 12:01

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