An apparatus that enables real time measurement of the spatial profile, circularity, centroid, astigmatism and M2 values of a laser beam generated by a high power laser beam. The apparatus employs the optics used in a process application, including a focus lens and cover glass. An attenuation module includes a pair of high reflecting mirror plates disposed in parallel, spaced apart relation to one another at a common angle of incidence to the laser beam. A beam dump is positioned out of a path of travel of the laser beam and in receiving relation to light reflected by the first and second mirrors. A camera detects spots of light that pass through the first and second mirrors. A high power attenuator formed by a highly reflective mirror pair is positioned between the source and the attenuation module. A second embodiment includes a single mirror plate having highly reflective surfaces.