Far-field images produced using random phase plates on a pulsed laser beam have been recorded by a CCD and then analysed. Spot sizes agree with diffraction theory while mean sizes of the pattern structures has been found larger than diffraction limit. Probability density distribution of intensity in the focal plane has not, in most cases, the expected exponential behaviour. Images obtained with reduced beam diameter show a definite central symmetry. Preliminary measurements of the optical breakdown threshold intensity in air show that threshold can be determined with much higher accuracy with RPP smoothed beams.