diam = 0.25 # diameter [um]
wavelength = 0.200 # lambda [um]
eps = 0.00001 # offset to avoid division by zero
radius = diam / 2
ap = 2 * pi * (NA / wavelength) * radius
d = 1 / 8 * ap**2 + 1 / 384 * ap**4 + 1 / 10240 * ap**6 # optimal d. Why!?
scale_z = wavelength / (2 * pi) * 1 / (1 - sqrt(1 - NA**2))
rspace = (np.arange(0, 0.5, 0.05) + eps) * NA / wavelength
fspace = np.arange(-2, 2, 0.05) / scale_z + 1j * d
cpsf = CPsf(0) # aberration free, only n = m = 0
t1 = time()
field1 = cpsf.V(n=0, m=0, r=rspace, f=fspace)
t2 = time()
print('field1 {:.6f} sec'.format(t2 - t1))
field1 = np.squeeze(field1)
I1 = np.square(np.abs(field1))
I1 *= (1 / I1.max())
ff, rr = np.meshgrid(np.real(fspace), rspace)
levels = np.sort(
np.concatenate((np.array([0.025, 0.05]), np.arange(0, 1, 0.1))))
c = p.contour(ff, rr, I1, levels)
p.clabel(c, inline=1)
p.xlabel('Focus [um]')
p.ylabel('Radius [um]')
p.title('Aberration free PSF, diameter = {} [um]'.format(diam))
