SERB School


Optical Metrology

Department of Physics, Tezpur University, Tezpur

June 01-21, 2016


Optical metrology covers measurement of physical parameters using light and light-based technologies. It does not cover optical spectroscopy. Light has been used for making precise measurement of length, angle and related parameters. With the advent of lasers, light based techniques are used for measurement in science and many branches of engineering. In fact light measurement touches all human endevours.

The course is therefore designed to give introduction to light sources and detectors and then discuss many different methods/techniques that are used to measure variety of physical measurements. The most potent technique is interferometry, which is used in variety of forms. Interferometry is used to measure length and its derivatives, radii of curvature, surface figure, refractive index etc. With the ready availability of CCD/CMOS detectors and enormous computing power, interferometry is supported with variety of phase algorithms, thereby presenting the results with high degree of accuracy and pleasing displays. Holography extended its applications to the study of real objects and their responses to external agency with interferometric precision. A close cousin of hologram interferometry, i.e. speckle interferometry, can be easily performed with electronic detection and hence finds many applications.

Many of the interferometric techniques have been configured using guided wave (fiber optics) and hence devices like Sagnac interferometer for measurement of rate of rotation and Michelson, Fabry-Perot and Mach-Zehnder interferometers for measuring strain, temperature etc. are now routinely used. Applications of MEMs and MOEMs technologies have made these devices very small in size albeit the basic principles of operation remaining the same.


schematic of a fiber optic gyroscope


Hilger-Chance refractometer prism