(self)
return 2*self.wavelen/pi
The minimal waist for which the gauss beam approximation is valid.

        The gauss beam is a solution to the paraxial equation. For curvatures
        that are too great it is not a valid approximation.

        Examples
        ========

        >>> from sympy.physics.gaussopt import BeamParameter
        >>> p = BeamParameter(530e-9, 1, w=1e-3)
        >>> p.waist_approximation_limit
        1.06e-6/pi
The minimal waist for which the gauss beam approximation is valid.
The minimal waist for which the gauss beam approximation is valid .
def waist_approximation_limit(self):
        """
        The minimal waist for which the gauss beam approximation is valid.

        The gauss beam is a solution to the paraxial equation. For curvatures
        that are too great it is not a valid approximation.

        Examples
        ========

        >>> from sympy.physics.gaussopt import BeamParameter
        >>> p = BeamParameter(530e-9, 1, w=1e-3)
        >>> p.waist_approximation_limit
        1.06e-6/pi
        """
        return 2*self.wavelen/pi
def waist_approximation_limit ( self ) : return 2 * self . wavelen / pi