Terahertz time-domain imaging targets the reconstruction
of the
full electromagnetic morphology of an object. In this spectral range,
the near-field propagation strongly affects the information in the
space–time domain in items with microscopic features. While
this often represents a challenge, as the information needs to be
disentangled to obtain high image fidelity, here, we show that such
a phenomenon can enable three-dimensional microscopy. Specifically,
we investigate the capability of the time-resolved nonlinear ghost
imaging methodology to implement field-sensitive micro-volumetry by
plane decomposition. We leverage the temporally resolved, field-sensitive
detection to “refocus” an image plane at an arbitrary
distance from the source, which defines the near-field condition,
and within a microscopic sample. Since space–time coupling
rapidly evolves and diffuses within subwavelength length scales, our
technique can separate and discriminate the information originating
from different planes at different depths. Our approach is particularly
suitable for objects with sparse micrometric details. Building upon
this principle, we demonstrate complex, time-domain volumetry resolving
internal object planes with subwavelength resolution, discussing the
range of applicability of our technique.