  We present an experimental approach to detect the saturated absorption
spectroscopy different from conventional scheme. Using this approach,
crossovers are removed to avoid their overlap with other peaks in the spectrum
and sensitivity of detection could be enhanced, so the spectrum could reflect
energy structure of atoms more explicitly. On the other hand, without harmful
influence from crossovers, locking range of the error signal is significantly
increased and symmetry of the dispersion line shape is perfectly reserved, so
reliability of frequency stabilization could be improved.
