Chapter 4 – Length Traceability Using Interferometry

This chapter presents the field of static length measurement. Some basic optics are introduced to lead up to the field of interferometry – length measurement using light. Different configurations of interferometer are presented including the Michelson, Twyman-Green, Fizeau, Jamin, Mach-Zehnder and Fabry-Perot. Gauge blocks as length standards are discussed in detail along with gauge block interferometry. The various sources of error in gauge block interferometry are presented and the chapter finishes with some alternative methods for gauge block measurement, such as double-sided interferometry.