  We propose and demonstrate a scheme to enable Doppler compensation within
optical cavities for atom interferometry at significantly increased mode
diameters. This has the potential to overcome the primary limitations in cavity
enhancement for atom interferometry, circumventing the cavity linewidth limit
and enabling mode filtering, power enhancement, and a large beam diameter
simultaneously. This approach combines a magnified linear cavity with an
intracavity Pockels cell. The Pockels cell introduces a voltage tunable
birefringence allowing the cavity mode frequencies to track the Raman lasers as
they scan to compensate for gravitationally induced Doppler shifts, removing
the dominant limitation of current cavity enhanced systems. A cavity is built
to this geometry and shown to simultaneously realize the capability required
for Doppler compensation, with a 5.04~mm $1/e^{2}$ diameter beam waist and an
enhancement factor of $>$5x at a finesse of 35. Furthermore, this has a tunable
Gouy phase, allowing the suppression of higher order spatial modes and the
avoidance of regions of instability. This approach can therefore enable
enhanced contrast and longer atom interferometry times while also enabling the
key features of cavity enhanced atom interferometry, power enhancement and the
reduction of aberrations. This is relevant to future reductions in the optical
power requirement of quantum technology, or in providing enhanced performance
for atom interferometers targeting fundamental science.
