A novel chip interferometry system for online surface measurements.

Abstract

This thesis documents the development of a novel chip interferometry system using advanced microtechnology and optical methodologies. This is the first time that this type of system has been reported in surface metrology. The system is designed to be compact, robust and stable even though it does not involve noise compensation and feedback control. Compared to currently available techniques, this system has great potential for on-line surface measurements. This application is based on a Michelson interferometer and wavelength scanning method. Considering the fabrication capability and effective cost, the system consists of two parts, an optical chip and an optical probe. The optical chip is the main focus of this research and it integrates a tuneable laser, a directional coupler, an optical isolator and a photodetector. The research approach for the optical chip is to use a planar silica motherboard for the passive circuitry onto which are assembled silicon daughterboards containing the different chip components that are to be integrated. The theory, methodology and technique for these individual chip components are explored. The optical probe is used to collimate, diffract and focus the light beam for surface scanning. The individual chip components and the optical probe are applied to build an experimental interferometry system. Initial surface measurements by this system have been carried out. The experimental results provide substantive evidence that the chip interferometry system is feasible for on-line surface measurements