Near-field microwave microscopy as a surface scanning tool

Jones, Dafydd 2024. Near-field microwave microscopy as a surface scanning tool. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

This thesis investigates using the near-field microwave microscope as a surface scanning tool on the macro scale, to assess components that are currently difficult to assess with readily available systems (for example, internal screw threads). A prototype has been created to represent a miniature version of a coordinate measurement machine (CMM) which can scan various surfaces based on a 2GHz microwave resonant probe. A novel side probe has also been manufactured that will enable the imaging of structures parallel to probe direction. Further to this, a low-cost oscillator circuit has been realised (using the resonant probe in its tank circuit) that could make this measurement system faster, cheaper, and hence mass manufacturable. Initial simulations have been carried out (COMSOL Multiphysics) to determine the feasibility of this application. This informed the experimentation phase, which investigated the prototype’s suitability for measurement in three distinct modes: measure frequency mode, constant frequency mode and contact mode. The side probe was then then investigated through experimental assessment of 3D internal and external threads, the results for the latter validated with another commercially available measurement system. Surface roughness was characterised using the constant frequency mode. Finally, a novel measurement mode was implemented with the resonant probe forming an oscillator, for fast and accurate read-out, and the results were compared with those taken with a vector network analyser. The success of this mode is a major step towards the commercialisation of the measurement system.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	1) Near-field Microwave Microscopy 2) Surface Scanning 3) Oscialltors 4) Surface Roughness Measurement 5) Non-Contact Metrology
Date of First Compliant Deposit:	28 June 2024
Last Modified:	28 Jun 2024 15:10
URI:	https://orca.cardiff.ac.uk/id/eprint/170030

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