A system for automatic positioning and alignment of fiber-tip interferometers

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Title: A system for automatic positioning and alignment of fiber-tip interferometers
Author: Jalan, Mahesh
Abstract: The research described in this thesis involves the design , development , and implementation of an automated positioning system for fiber -optic interferometric sensors . The Fiber -Tip Interferometer (FTI ) is an essential component in the proven Thermo -Acousto -Photonic NDE technique for characterizing a wide range of engineering materials including polymers , semiconductors and composites . The need to adapt the fiber -optic interferometric system to an industrial environment and to achieve precision control for optimizing interferometric contrast motivated the development of an automated , self -aligning FTI system design . The design enables high -resolution positioning and alignment by eliminating manual subjectivity and allows significantly improved repeatability and accuracy to be attained . Opto -electronic and electromechanical devices including a GRIN lens , 2x2 fused bi -conical taper couplers , photodiodes , motor -controlled tip /tilt stages , oscilloscopes , and a PCI card , constitute a closed -loop system with a feedback controller . The system is controlled by and communicates with a computer console using LabVIEW , a graphical language developed by National Instruments . Specifically , alignment is quantified by scanning the voltage readings at various orientations of the GRIN lens . The experimental setup specific to achieving maximum interferometric contrast intensity when interrogating silicon wafers with various surface depositions is discussed . Results corresponding to the interferometric contrast data obtained at several different standoff distances (Fizeau Cavity magnitudes ) demonstrate the robustness of the novel design .
URI: http : / /hdl .handle .net /1969 .1 /1234
Date: 2004-11-15

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A system for automatic positioning and alignment of fiber-tip interferometers. Available electronically from http : / /hdl .handle .net /1969 .1 /1234 .

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