Experimental investigation of Bessel beam characteristics

We report on an experimental characterization of Bessel beams with finite apertures. We show that real Bessel beams can be generated with intensity profiles that closely resemble the ideal J(0)(2) transverseintensity distribution of Bessel beams. We also show interferometrically that these beams have planar phase fronts with pi-phase shifts from one Bessel ring to the next. We report tolerance conditions for Bessel beam generation and give an example of this generation that uses an unstable resonator as the light source.