Calculates the Conversion Factor and physical amplitude of motion in nms 
    by comparison of the ratio of the heights of the z signal and 
    second harmonic of z.

    Parameters
    ----------
    z : ndarray
        array containing z signal in volts
    z2 : ndarray
        array containing second harmonic of z signal in volts
    NA : float
        NA of mirror used in experiment

    Returns
    -------
    z0 : float
        Physical average amplitude of motion in nms
    ConvFactor : float
        Conversion Factor between volts and nms

def calc_z0_and_conv_factor_from_ratio_of_harmonics(z, z2, NA=0.999):
    """
    Calculates the Conversion Factor and physical amplitude of motion in nms 
    by comparison of the ratio of the heights of the z signal and 
    second harmonic of z.

    Parameters
    ----------
    z : ndarray
        array containing z signal in volts
    z2 : ndarray
        array containing second harmonic of z signal in volts
    NA : float
        NA of mirror used in experiment

    Returns
    -------
    z0 : float
        Physical average amplitude of motion in nms
    ConvFactor : float
        Conversion Factor between volts and nms
    """
    V1 = calc_mean_amp(z)
    V2 = calc_mean_amp(z2)
    ratio = V2/V1
    beta = 4*ratio
    laserWavelength = 1550e-9 # in m
    k0 = (2*pi)/(laserWavelength)
    WaistSize = laserWavelength/(pi*NA)
    Zr = pi*WaistSize**2/laserWavelength
    z0 = beta/(k0 - 1/Zr)
    ConvFactor = V1/z0
    T0 = 300
    return z0, ConvFactor