def angstroms_to_s(offset_us, source_to_detector_m, array):
    """convert array in angstroms into s

    Parameters:
    ===========
    numpy array of lambda in angstroms
    offset_us: float. Delay of detector in us
    source_to_detector_m: float. Distance source to detector in m

    Returns:
    ========
    numpy array of time in s
    """
    return source_to_detector_m * array / 3956.0 - offset_us * 1e-06
