A Method for Measurement of Nonlinearity of Laser Interferometer Based on Optical Frequency Tuning

Abstract

Abstract:A method for measuring the nonlinearity of laser interferometer using optical frequency tuning technique is presented in this paper. The basic principle of this method is to make the fractional part of an interference fringe change by tuning the laser frequency and determining the nonlinearity of interferometer by comparing the fractional fringe change measured by the interferometer to that calculated from the laser frequency change. An experimental interferometric system with a wavelength tunable laser source is set up and the nonlinearity of the interferometer is measured. Since it does not require the precise displacement mechanism to produce the optical path difference change, this method is more convenient to use and may achieve a higher accuracy than the conventional measurement methods. The nonlinearity of the arbitrary interferometric phase can be measured by changing the laser frequency with this method. Experiments results have shown that the repeatability of nonlinearity measurement is less than 0.2 nm. This method can be applied to interferometry-based high precision dimensional measurements, such as coordinate measurement and displacement sensor calibration.

Dual Doppler Effect in Wedge-Type Photonic Crystals

“…In addition, we have shown that the outgoing direction of the complex harmonic coupling to the vacuum can be predicted precisely by using multiple reciprocal unit cells. The novel phenomenon could benefit any technique currently exploiting the conventional Doppler effect, such as the Doppler cooling of atomic gases, radar deception, invisibility cloaks, microstructure dual frequency interferometer 19 , 20 and so on. The technique is also applicable to systems with tunable sources of terahertz radiation and other frequency regions that are difficult to access.…”