... Then 2 a A( ρ) D 2 h x dx J0 (x) 2 ρ 2 ρ 2 a h h 2 a xJ0 (x)dx D [xJ1 (x)]0 2 ρ 2 ρ 2J1 (2 a ) ah J1 (2 a ) D π a h D ρ 2 a D and finally A( ρ) D π a h Jinc (2 a ), where Jinc(x) D 2J1 (x) ... is usually shown graphically by plotting a polar diagram of the attenuation, A, radially against the angle of phase-shift, eliminating ν as a variable The result is called a Nyquist diagram (Fig ... on a distant plane surface: A( ρ, φ) D a[ e2πiaρ cos φ C e2πiaρ cos(π φ) ] D 2a cos (2 a cos φ), and the intensity pattern is given by I (ρ, φ) D 4a cos2 (2 a cos φ), which has maxima when 2a ...