White light interferometry in measurements of micro volumes

• Main Author: Ferri, Carlo
• Published: Cardiff University 2006
• Subjects: 621.36
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.583806

A procedure for measuring micro-volumes of solids with irregular and complex boundaries of both concave and convex forms has been developed. Advantages, limitations and potential applications of the developed procedure are identified and discussed. The precision of this procedure is demonstrated in the case of a con vex form. In the light of the key role of metrology in the current trend toward product miniaturisation, the need for dedicating resources and effort to assessing quantitatively the performances of measuring processes is most apparent. The developed procedure is based on white light interferometric microscopy. In order to enable the deployment of this measuring system in the developed procedure and in agreement with the centrality of metrology mentioned above, an investigation of white light interferometric microscopy has been carried out from a user perspective. In particular, two sources of variability were identified and experimentally quantified and the precision in repeatability conditions was estimated when measuring length along the z-axis in a pre-specified micro-metric range. A critical analysis of the calibration procedure built in the investigated microscope has also been conducted. In order to overcome the pitfalls discovered in such an analysis, a spline-based calibration procedure has been developed and demonstrated. In addition, the control methods needed for the practical usage of the proposed calibration procedure have been developed. Calibration studies are made possible by the provision of traceable reference materials. Therefore, a cost-effective and versatile procedure for the build ing of traceable reference samples of length in the micrometric range was developed. The proposed method used standard gauge blocks commonly found in metrology laboratories.