Like in any other welding technique, creation of pores and defects during laser welding can lead to component failure and thus cannot be tolerated. Post-built inspection is required to make sure the printed parts are defects-free. These inspections can take time and are complicated in case of large parts. A solution is to use in situ process monitoring to detect the creation of defects, which could in turn be corrected during the printing itself. However, the relationship between pores creation and in situ monitoring still need to be understood. In this work, we use x-ray computed tomography to detect pores and correlate them to pyrometry and high speed thermal imaging signal. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.