The Evolution Of Interferometry From Metrology To Biomedical Applications

Interferometry is a powerful tool often used for the metrology of surfaces with many applications in industries such as optical fabrication, data storage, machine tool, and semiconductor. For many years interferometers have been built into microscopes so surface microstructure can be measured. Phase-shifting interferometric techniques have provided an extremely accurate rapid way of getting the interferogram data into the computer and the inherent noise in the data taking process is so low that in a good environment angstrom or sub-angstrom surface height or thickness measurements can be performed. The recent development of single-shot phase-shifting techniques has made it possible to perform accurate phase measurement techniques in less than ideal environments and to make movies showing how surface shape or optical thickness is varying with time. These same interferometric techniques can be applied to biomedical applications. This paper will trace the history of the development of these interferometric techniques that led to the application of these techniques to looking at cells and tissues.