The laser beam absorption lengths of CO2 (10.6 mum wavelength) and a high power diode laser (HPDL) (810 nm wavelength) radiation for an Al2O3/SiO2-based refractory have been determined through the application of Beer-Lambert's law. The findings revealed marked differences in the absorption lengths despite the material having similar beam absorption coefficients for both lasers. The absorption lengths for the Al2O3/SiO2-based refractory of CO2 and a HPDL radiation were calculated as being 345 +/- 22 and 198 +/- 15 mum, respectively. Moreover, this method of laser beam absorption length determination, which has hitherto been used predominantly with lasers operated in the pulsed mode, is shown to be valid for use with lasers operated in the continuous wave (CW) mode, depending upon the material being treated.