This estimate is based on optical measurements of dye accumulation in stain layer and measurements of thickness of stain layer via fluorescence microscope examination.
E p is the laser pulse energy.
E th is the apparent threshold laser pulse energy that will break the weld. Not on the amount of excess unbound water. There was no significant difference in weld strength between welding dripping wet tissues vs well blotted tissues. There is a difference if the stain layer is heavily stained. Irradiation through the tissue allows direct irradiation on the weld surface which achieves the highest peak temperatures for the least laser pulse energy.