Actively stabilised optical device for potential on-line assessment of surfaces in ultra precision manufacturing

This paper introduces a new surface measurement technique for potential online nano scale surface measurement applications. It attempts to generate a robust and miniature measurement device for future development into a multi-probe array measurement system. In this research, both the Fibre-Optic-Interferometry and the Wavelength-Division-Multiplexing techniques have been used, so that the optical probe and the optical interferometer are well-spaced allowing flexibility for on-line measurement. This system provides a self-reference signal to calibrate and stabilise the optical detection with high common-mode noise suppression by adopting an active phase tracking homodyne technique. Experiments were carried out to test the feasibility of the system. Properties of the technique were also discussed. The method should be a potential new tool for advanced manufacturing, especially for quality and process control in ultra precision manufacturing.