  Atom interferometer-based gyroscopes are expected to have a wide range of
applications due to their high sensitivity. However, their dynamic range is
limited by dephasing caused by velocity-dependent Sagnac phase shift in
combination with the velocity distribution of the atoms, restricting
measurements of large angular velocities. In this study, we present a method
for restoring the contrast deterioration in rotation rate measurements with
interferometer gyroscopes using atomic beams. Our findings confirm that by
introducing the pseudo-rotation effect with appropriate two-photon detunings
for Raman lights in the interferometer, it is possible to effectively cancel
the rotation of all atoms in the velocity distribution of the beam.
Consequently, the contrast is unaffected by the rotation. Furthermore, we
applied this method to an interferometer gyroscope with counterpropagating
atomic beams sharing the same Raman lights. We also found that the rotation
rate of the system can be estimated through the detunings points where the
phase difference between the two interferometers is zero. This approach ensures
that the scale factor of the atom interferometer gyroscope is independent of
the velocity fluctuation of the atomic beam. We demonstrate our technique using
the interferometer gyroscope of thermal atomic beams of rubidium-87, achieving
a measurement of rotation rate of $\mathrm{{1.0}^{\circ}/s}$ even with an
acceleration of 0.68$\mathrm{m/s^2}$ on a three-axis rotation table. This
simple and robust dispersion compensation method with Raman light detuning
benefits dynamic rotation-rate measurements in field applications such as the
inertial navigation of vehicles.
