Surface Roughness Characterization of hole walls in fibercomposites

Abstract: In the manufacturing of fibrecomposite structures for the aircraft industry many holes are drilled through the composite for the attachment of the composite to a metal frame. These holes have a Ra specification of the cylindrical walls. The measurement of this roughness is tedious work if made by a stylus profiler. In this thesis, a design concept is created and tested by using OSLO raytracing program. This employed raytracing simulation is used to analyze and study variation of the surface features of the hole and evaluate the corresponding resultant image afterwards using image quality indicators. On large scale the aim of the thesis work is to investigate the possibilities of detecting defects of the cylindrical walls and get a quantitative measurement of the roughness of the hole by employing the concept of optical cylindrical imaging. Keywords: Surface roughness, Light scattering, Diffraction , Reflection, Raytracing analysis, Wavefront analysis, Spot diagram, Diffraction limit, PSF, MTF, Energy analysis, Optimization, Entrance pupil, Exit pupil, Carbon Fiber Reinforced Polymers (CFRP), Axicon, He Ne Laser.