Hi, I'm writing a review about photobiomodulation and I'm wondering how I can calculate the fluence of a laser from its irradiance. like there is this article that has used an Nd: YAG laser at 1.25 W power, 15 Hz frequency, and 320 μm of fiber diameter, 2mm from tissue, for 1 min and repeated five times. it has also mentioned its power density(irradiance) of 268.57 W/ cm2. is there any way to calculate the energy density(fluence) of this laser from the mentioned parameters? what's the mathematical relation between power density and energy density?

I would be truly grateful if anyone could answer me.