k=7.6675*10^14,
η =6.34963*10^-12,
α0 = 0,
α1=1.26993*10^-11,
α2=1.90489*10^-11,
α3 =2.3282*10^-11,
α4=2.64568*10^-11,
P0 = 1.0,
P2 =1/2 (-1 + 3 Cos[θ^2),
P4 = 1/8 (3 - 30 Cos[θ]^2 + 35 Cos[θ]^4),
Exp1= Exp[ i * η * Log[(Csc[θ]/2])^2] ],
Exp2 = Exp[ i * η * Log[(Csc[[Pi]/2 - θ/2])^2] ]