Development of a laser based surface profilometer using the principle of optical triangulation
Collins, David Andrew (2005) Development of a laser based surface profilometer using the principle of optical triangulation. Master of Engineering thesis, Dublin City University.
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The metrology industry is constantly looking for new ways to accurately and quickly inspect and digitise surface topographies including the calculation o f surface roughness parameters and generating point clouds (a collection o f 3-dimensional points which describe a surface or surfaces) for modelling or reverse engineering purposes. Many types o f profllometer systems currently exist and the past decade has seen the rise in popularity o f optical based systems, however most optical profilometers are expensive to purchase and to maintain. The development o f optical profilometers can also be exceptionally complex depending on the type o f system and its fragility may not make it suitable for m ost workshop or factory floor applications. This project covers the development of a profllometer using the principle of optical triangulation.
The developed system has a scanning table area of 200 by 120 millimetres and a vertical measurement range of five millimetres. The position o f the laser sensor above the target surface also has an adjustable range of 15 millimetres. A control program was developed to automatically scan user selected part and surface areas. This new system was characterised in terms of dimensional accuracy. The maximum cosine error of the system was measured at 0.07°. Dynamic accuracy of the system was measured at 2fim in the Z-axis (height) and at approximately 10|a.m in the X and Y axes. Good dimensional correlation between scanned parts (coins, screws, washers, and fibre optic lens moulds) were achieved. Testing of the system will be also discussed, including the limitations of the profllometer and possible improvements to the system.
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