A novel chip interferometry system for online surface measurements.

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.