Optical Cooperativity in regards to Fringe Projection Systems
Carson Rooms 3 and 4, enter at Carson 3
Omar Abo-Namous - Representing Institute off Measurement and Automatic Control
Abstract:
Fringe projection techniques provide an attractive areal and non-intrusive metrology system for industrial usage with a widely adaptable resolution and measurement accuracy. It is based on the triangulation between a structured light source and the sensor. As such, it heavily depends on the characteristics of the measured surface. Different surface characteristics such as its gloss, opacity or material can facilitate or complicate optical measurement using triangulation technique respectively. We summarize those characteristics into the term ‘optical cooperativity’.
Two main surface characteristics stand out: surface gloss and subsurface scattering. Subsurface scattering causes a surface indifferent blur of the projected light such that the triangulation is affected. This effect can be prominently found on semitransparent material such as acrylic glass or other synthetic materials.
The main focus of optical cooperativity in the industrial field – and as related to metallic surfaces – is the glossiness of a surface, which is an issue with freshly finished industrial parts. The glossiness depends greatly on the submicrometer surface roughness and on the wavelength of the light projected and it can be affected by the anisotropic property of the metallic surface. Specially parts with complex geometries – such as gearwheels – become hard to measure when their surface is glossy.
The aim of the project ‘Non-contact geometry inspection of finished rotationally symmetrical workpieces with optically non-cooperative surfaces’ is to cover the term ‘optical cooperativity’ and to find methods to measure optically non-cooperative surfaces by either changing their respective surface characteristics or by changing the system parameters of the fringe projection system.
A change in the surface glossiness has been achieved by roughening up the surface mechanically by blasting the surface, chemically by etching the surface with different acids and electrochemically and by applying a thin quasi-lambertian layer onto the surface with water condensate or soot. In practice, the employed method has to be determined by the material used.
The presentation – including a technical paper - will give a brief overview of the different works being done within the scope of the project.
