Abstract: The method of fitting hyperbola with singular value decomposition(SVD) was used to measure the laser beam quality parameters. The advan tages and disadvantages of using the normal equations to fit a hyperbola were an alyzed. The hyperbola fitted by SVD was used to express the change of the laser beam’s width, and the rules for estimating the goodnessoffit were offered. The fitting precisions of hyperbolas fit with the normal equations and the SVD were compared. The result showed that the precisions and the goodness-of-fit were affected better in the fitting hyperbola with SVD for laser measure.

Key words: singular value decomposition(SVD), laser waist, M2 factor, fitting precision, goodness of fit