The laser power is a processing parameter governing the quality of laser machining. Therefore frequent checking of laser power is required. The TEM-modes of high power laser beams are usually different from TEM00-mode, where the modes may vary with laser power. The intensity distribution of the laser beam will be asymmetrical and instable. Resultant detrimental effects on laser power measurement may usually be avoided by an increased effort for detector positioning. This paper discusses an alternative laser power detector system, where the measurement is independent of the TEM-modes. Exact positioning of the detector is not required.