lambda = 1.064  * 10^-6
epsilon =1
kappa=10^-7
z1=2.75
z2=4.25
L=3000
a=0.475
b0=1.47 * 10^-4
w0=0.01
theta1=ArcTan[a/z1]
theta2=ArcTan[a/z2]
deltaalpha= a/L*180 / Pi
thetag=lambda/(Pi w0)
seismic={4 Pi / lambda / Sqrt[2]} 10^-8

dangle=Sqrt[NIntegrate[{Exp[5.5 theta]Sin[theta]^3}/{theta^4 Cos[theta]^2},{theta,theta2,theta1}]]
dh={lambda^2 epsilon kappa}/{L a} Sqrt[b0/32 Pi^3] Sqrt[NIntegrate[{Exp[5.5 theta]Sin[theta]^3}/{theta^4 Cos[theta]^2},{theta,theta2,theta1}]]
dhs = dh seismic

Plot[0.83Exp[-5.5 theta],{theta,0,0.2}]
Plot[b0 Exp[5.5 theta],{theta,theta1,theta2}]