Abstract: | We present an original experiment describing a focused Gaussian laser beam by using second-harmonic generation (SHG) in a thin strip of a nonlinear optical material, in this case KTP doubling of an Nd:YAG laser at 1.064 μm. The dependence of the SHG efficiency on the fundamental beam radius allows the determination of beam parameters by harmonic-power measurements. The characterization of a telescope shows the good precision of this method in radii in the range of 10-100 μm. The average accuracy is 4% for the radius determination and 1.5% for the beam-waist localization. |