The kz direction definitions of 1d/2d Gaussian beams are inconsistent

[likooooo]

Thank you for sharing this amazing project, it has helped me a lot.
I have some confuse about gauss_beam in scalar_sources_X.py/scalar_sources_XY.py

• scalar_sources_XY.py:170

phase2 = np.exp(1j * (k * z0x - phaseGouy_x + k * ((self.X * np.cos(beta) + self.Y * np.sin(beta))**2) / (2 * R_x))) * \
    np.exp(1j * (k * z0y - phaseGouy_y + k * ((-self.X * np.sin(beta) + self.Y * np.cos(beta))**2) / (2 * R_y)))

• scalar_sources_X.py:115

phase2 = np.exp(1j * (-k * z0 - phaseGouy + k * (self.x - x0)**2 /
                        (2 * R)))

they have diffrent direction in kz, I'm not sure if this is a bug.
it would be even better if there were more documentation on coordinate system definitions.

Thanks.