Computational imaging using a mode-mixing cavity at microwave frequencies
Résumé
We present a 3D computational imaging system based on a mode-mixing cavity at microwave
frequencies. The core component of this system is an electrically large rectangular cavity with one
corner re-shaped to catalyze mode mixing, often called a Sinai Billiard. The front side of the cavity
is perforated with a grid of periodic apertures that sample the cavity modes and project them into
the imaging scene. The radiated fields are scattered by the scene and are measured by low gain
probe antennas. The complex radiation patterns generated by the cavity thus encode the scene information
onto a set of frequency modes. Assuming the first Born approximation for scattering
dynamics, the received signal is processed using computational methods to reconstruct a 3D image
of the scene with resolution determined by the diffraction limit. The proposed mode-mixing cavity
is simple to fabricate, exhibits low losses, and can generate highly diverse measurement modes.
The imaging system demonstrated in this letter can find application in security screening and medical
diagnostic imaging.