def get_ot_force(h5_data, species_name='filament-trap'):
    """ Get force on bead from optical based on position"""
    k_spring = h5_data['optical_trap_data/' +
                       species_name].attrs['trap_spring']
    trap_pos_arr = h5_data['optical_trap_data/' +
                           species_name + '/trap_position'][:, :, 0]
    bead_pos_arr = h5_data['optical_trap_data/' +
                           species_name + '/bead_position'][:, :, 0]
    time = h5_data['optical_trap_data/' + species_name + '/time'][...]
    return time, k_spring * (trap_pos_arr - bead_pos_arr)