title: Fiber optic projection-imaging system for shape measurement in confined space.
abstract: A fiber-based projection-imaging system is proposed for shape measurement in confined space. Owing to the flexibility of imaging fibers, the system can be used in special scenarios that are difficult for conventional experimental setups. Three experiments: open space, closed space, and underwater are designed to demonstrate the strength and weakness of the system. It is shown that when proper alignment is possible, relatively high accuracy can be achieved; the error is less than 2% of the overall height of a specimen. In situations where alignment is difficult, significantly increased error is observed. The error is in the form of gross-scale geometrical distortion; for example, flat surface is reconstructed with curvature. In addition, the imaging fibers may introduce fine-scale noise into phase measurement, which has to be suppressed by smoothing filters. Based on results and analysis, it is found that although a fiber-based system has its unique strength, existing calibration and processing methods for fringe patterns have to be modified to overcome its drawbacks so as to accommodate wider applications.
authors.affiliation: Engineering Product Design, Singapore University of Technology and Design, Singapore 138682.
authors.forename: Lujie
authors.initials: L
authors.lastname: Chen
authors.affiliation: Engineering Product Design, Singapore University of Technology and Design, Singapore 138682.
authors.forename: Viswanath
authors.initials: V
authors.lastname: Bavigadda
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228.
authors.forename: Theodoros
authors.initials: T
authors.lastname: Kofidis
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Howe
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006696:Holography / Q000295:instrumentation*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D007909:Lenses; D008027:Light; D008962:Models, Theoretical; D010363:Pattern Recognition, Automated / Q000379:methods*; D012542:Scattering, Radiation