def ev_to_image_number(offset_us, source_to_detector_m, time_resolution_us, t_start_us, array):
    # delay values is normal 2.99 us with NONE actual MCP delay settings
    """convert energy (eV) to image numbers (#)

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

    Returns:
    ========
    image numbers: array of image number
    """
    time_tot_us = np.sqrt(81.787 / (array * 1000)) * source_to_detector_m * 100 / 0.3956
    time_record_us = (time_tot_us + offset_us)
    image_number = (time_record_us - t_start_us) / time_resolution_us
    return image_number