def METHOD_NAME(self):
    """Return wavelength low and high limits.
    Returns:
        (tuple): two floats tuple (low limit, high limit) [Å].
    """
    _low, _high = self.get_limits()
    self._wavelength_limits = (
        self.calculate_wavelength(_high),
        self.calculate_wavelength(_low),
    )
    return self._wavelength_limits