def profile(self, z, f, dx=1.):
"""
Beam's complex amplitude at an axial distance z from waist.
Plane lies perpendicular to z axis and has the same shape as f.
========Input=========
z : Axial distance from waist
f : 2D Array defining the output array shape
dx : Pixel pitch (default value is unit of measurement)
========Raises========
TypeError: If f isn't a 2D array
========Output========
g : 2D complex array (complex amplitude at an axial distance z from waist centered at z axis)
"""
if (len(tl.shape(f)) != 2):
raise TypeError('f must be a 2D array')
n, m = tl.shape(f)
x = tl.arange(-m * dx / 2, m * dx / 2, dx)
y = tl.arange(-n * dx / 2, n * dx / 2, dx)
X, Y = tl.meshgrid(x, y)
R = tl.sqrt(X**2 + Y**2)
P = tl.arctan(Y / X)
g = self.value(R, P, z)
return g
def gouy_phase(self, z): # Phase retardation due to Gouy effect
return tl.arctan(z / self.zO)