Terahertz Phase Retrieval Imaging with Multiple-Plane Data
Résumé
Recent results in the field of phase retrieval from intensity distributions recorded in the terahertz frequency range in planes located at different distances from the object are discussed. The experiments were carried out in transmissive [1] and reflective [2] configurations. Registration of data with a high dynamic range is proposed, which allows detecting the distribution of low-intensity high spatial frequencies carrying information about small object details, without overexposure in the near-axial region. Technically, this is implemented using a single detector and two lock-in amplifiers operating with the complimentary sensitivity setting. The proposed approach provides high spatial resolution and allows measuring the surface relief and visualizing the internal structure of objects.