Fig. 3
From: Single-shot measurement of the orbital-angular-momentum spectrum of light
Experimental results obtained with fields produced by parametric down-conversion. a, b Measured output interferogram and the azimuthal intensity for δ = δ c and δ = δ d , respectively. c The normalized measured spectrum \({\bar S_l}\) as computed using Eq. (8), and the normalized theoretical spectrum as calculated using the formalism of ref. 42, for our setup parameters, namely, a type-I collinear down-conversion with a 2-mm thick BBO crystal and a 0.85-mm beam-waist pump laser. The theoretical spectrum has no fitting parameters. The angular Schmidt number \(K = 1{\rm{/}}\left( {\mathop {\sum}\nolimits_l \bar S_l^2} \right)\) for the measured spectrum is evaluated to be 82.1
