The measurement of rough surface topography using coherence scanning interferometry

This guide describes good practice for the measurement and characterisation of rough surface topography using coherence scanning interferometry (commonly referred to as vertical scanning white light interferometry). It is aimed at users of coherence scanning interferometry for the optical measurement of surface texture within production and research environments. The general guidelines described herein can be applied to the measurement of rough surfaces exhibiting different types of surface topography. For the purpose of this guide, the definition of a rough surface is one that has features with heights ranging from approximately 10 nm to less than 100 µ

A Technique of Direct Tension Measurement of a Strung Fine Wire

We present a new technique of direct measurement of wire tensions in wire chambers. A specially designed circuit plucks the wire using the Lorentz force and measures the frequency of damped transverse oscillations of the wire. The technique avoids the usual time-consuming necessity of tuning circuit parameter to a resonance. It allows a fast and convenient determination of tensions and is straightforward to implement.Comment: 15 pages with 9 figure

A comparative study of fuzzy logic controllers for autonomous robots.

This paper presents the results from an experimental comparison of a number of fuzzy logic controllers performing mobile robot navigation. An experiment is described which requires the robot to complete a complex, measurable navigational task. The world's first generalised type-2 fuzzy logic controller is compared to a type-1 and a type-2 interval controller. Visual and statistical analyses show that the generalised type-2 fuzzy controller gives a better performance in consistency and smoothness. The impact of this paper comes primarily from the rigorous use of statistical analysis in mobile robot navigation

Surface measurement errors using commercial scanning white light interferometers

This paper examines the performance of commercial scanning white light interferometers in a range of measurement tasks. A step height artefact is used to investigate the response of the instruments at a discontinuity, while gratings with sinusoidal and rectangular profiles are used to investigate the effects of surface gradient and spatial frequency. Results are compared with measurements made with tapping mode atomic force microscopy and discrepancies are discussed with reference to error mechanisms put forward in the published literature. As expected it is found that most instruments report errors when used in regions close to a discontinuity or those with a surface gradient that is large compared to the acceptance angle of the objective lens. Amongst other findings, however, we report systematic errors that are observed when the surface gradient is considerably smaller. Although these errors are typically less than the mean wavelength they are significant compared to the instrument resolution and indicate that current scanning white light interferometers should be used with some caution if sub-wavelength accuracy is required