Real time laser beam analysis system for high power lasers

Abstract

A laser beam analysis system, with all passive optical components, has been developed that permits the real time measurement of a high power laser beam in the tens of kilowatts which can provide the laser's spatial profile, circularity, centroid, astigmatism and M-squared values using all the optics of a process application, including the focus lens and cover glass. At the heart of the technique is a Fabry-Perot resonator used with a focusing lens that provide a means to both attenuate and provide a multiplicity of focused laser spots each representing a spatial slice of the focused beam waist of interest onto a single CCD or CMOS camera. This arrangement provides real time data on the laser system's beam properties and is the basis upon which this work it done. The coatings of the Fabry-Perot resonator provide a high degree of attenuation of the input beam so that thermal lensing is not a factor in the measurement. By adjusting incident angle and spacing between the mirrors of the Fabry-Perot resonator, a large number of spatial cross sections can be seen on the detector. This permits then the possibility of evaluating any focusing objective whether long or short in focal length.