1：Experimental Design and Method Selection:

A new measuring technique was developed to determine the coupling efficiency and link the results to the process temperature. The method consists of assessing the temperature–time curve of the probe irradiation and the subsequent cooling regime, then determining the energy coupling efficiency through the alignment of the experimental temperature–time curves with a heat flow computation.

2：Sample Selection and Data Sources:

AISI 304 stainless steel probes of 60 mm in diameter and 3 mm in thickness were used. The surface was polished to reduce the effect of surface roughness.

3：List of Experimental Equipment and Materials:

Three different CW lasers sources were used: a CO2-laser, a fiber laser, and a frequency-doubled disk laser with wavelengths of 10.6 μm, 1.07 μm, and 515 nm, respectively.

4：6 μm, 07 μm, and 515 nm, respectively. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The probes were irradiated centrically with a stationary laser beam; the temperature increase of the probe was captured from underneath using a thermographic setup. The probes were irradiated for 5 s; the temperature signal was recorded for 15 s to also capture the cooling regime.

5：Data Analysis Methods:

A theoretical temperature–time curve was calculated through a heat flow computation. The model equations were numerically solved to inversely calculate the energy coupling efficiency.