Highly-Repetitive Optical Coherence Tomography Using Time-Stretch Dispersive Fourier Transformation and in Situ Measurement for Laser Welding Process

Abstract

A technique called time-stretch dispersive Fourier transformation provides the rapid spectroscopy of the ultrashort pulses of light at a repetition from a few tens MHz to a few tens GHz. Time-stretch OCT using time-stretch dispersive Fourier transformation has also been studied in recent years. This paper reviews the recent researches and shows the principle of time-stretch OCT. We also introduce the in-situ measurement of a keyhole shape in the laser welding process that we are developing and show how to achieve real-time signal analysis in time-stretch OCT as well as the current status of real-time measurement.