  We introduce a novel in-situ strong field ionization tomography approach for
characterizing the spatial density distribution of gas jets. We show that for
typical intensities in high harmonic generation experiments, the strong field
ionization mechanism used in our approach provides an improvement in the
resolution close to factor of 2 (resolving about 8 times smaller voxel volume),
when compared to linear/single-photon imaging modalities.
  We find, that while the depth of scan in linear tomography is limited by
resolution loss due to the divergence of the driving laser beam, in the
proposed approach the depth of focus is localized due to the inherent physical
nature of strong-field interaction and discuss implications of these findings.
We explore key aspects of the proposed method and compare it with commonly used
single- and multi-photon imaging mechanisms. The proposed method will be
particularly useful for strong field and attosecond science experiments.
