A Robust Baseline and Reference Modification and Acquisition Algorithm for Accurate THz Imaging

This paper reports an accurate baseline and reference modification and acquisition algorithm for terahertz (THz) reflection measurements. The algorithm solves the spatial phase variation problem, which is a major accuracy limitation of THz reflection imaging. It also overcomes the sampling error problem without taking multiple measurements by utilizing two-dimensional data fitting. The algorithm records the spatial information and the laser power status as a database to precisely modify the baseline and reference in a measurement, providing a simple, efficient, and accurate real-time baseline and reference acquisition method. The experimental results show that the algorithm significantly improves the accuracy of the extracted optical properties of the sample with only half of the time required in a traditional THz imaging by avoiding additional baseline and reference measurements. The strong robustness of the algorithm is also proved by the experiment, giving a stable performance against laser power fluctuations.