ContourPlot[(1.80016*^-6-y^2)/(7.04932*10^-6-y^2)+((1+(1.9507*10^-21*y^2)/(7.04932*10^-6-y^2)^4)*Sinh[x])/(Cosh[x]+Sqrt[1-(1.9507*10^-21*y^2*Sinh[x]^2)/(7.04932*10^-6-y^2)^4]),{x,-2,2},{y,-.04,.04}]