  We report on results of the on-ground X-ray calibration of the Lobster Eye
Imager for Astronomy (LEIA), an experimental space wide-field (18.6*18.6 square
degrees) X-ray telescope built from novel lobster eye mirco-pore optics. LEIA
was successfully launched on July 27, 2022 onboard the SATech-01 satellite. To
achieve full characterisation of its performance before launch, a series of
tests and calibrations have been carried out at different levels of devices,
assemblies and the complete module. In this paper, we present the results of
the end-to-end calibration campaign of the complete module carried out at the
100-m X-ray Test Facility at IHEP. The PSF, effective area and energy response
of the detectors were measured in a wide range of incident directions at
several X-ray line energies. The distributions of the PSF and effective areas
are roughly uniform across the FoV, in large agreement with the prediction of
lobster-eye optics. The mild variations and deviations from the prediction of
idealized lobster-eye optics can be understood to be caused by the imperfect
shapes and alignment of the micro-pores as well as the obscuration by the
supporting frames, which can be well reproduced by MC simulations. The spatial
resolution of LEIA defined by the FWHM of the focal spot ranges from 4-8 arcmin
with a median of 5.7. The measured effective areas are in range of 2-3 $cm^2$
at ~1.25 keV across the entire FoV, and its dependence on photon energy is in
large agreement with simulations. The gains of the CMOS sensors are in range of
6.5-6.9 eV/DN, and the energy resolutions in the range of ~120-140 eV at 1.25
keV and ~170-190 eV at 4.5 keV. These results have been ingested into the
calibration database and applied to the analysis of the scientific data
acquired by LEIA. This work paves the way for the calibration of the Wide-field
X-Ray Telescope modules of the Einstein Probe mission.
