Abstract-Terahertz pulse time-domain holography method for phase imaging of breast tissue

Nikolay S. Balbekin, Quentin Cassar,  Olga A. Smolyanskaya, Maksim S. Kulya,  Nikolay V. Petrov,  Gaetan MacGrogan,  Jean-Paul Guillet,  Patrick Mounaix,  Valery V. Tuchin, 

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10887/108870G/Terahertz-pulse-time-domain-holography-method-for-phase-imaging-of/10.1117/12.2508711.short?SSO=1

Pulse holographic imaging along with time-domain spectroscopy scan and tomographic techniques are of great interest. Since the advantages of holography are the lack of focusing optics and high spatial resolution, and, comparing with tomography, less computation cost for numerical reconstruction, this technique is preferable for the analysis of thin histological samples. In this work we have created the experimental scheme that involves measurement of diffraction pattern of the collimated THz pulse field spatial distribution at some distance behind the object in the time-domain mode, thus allowing reconstruction of amplitude and phase distribution at the object plane by numerical backpropagation of the wavefront in the spectral domain. In our experiment, we used a breast biopsy sample containing cancer tissues, we also performed numerical simulations accounting for experimental conditions to confirm the conceptual applicability of the reconstruction method.

Abstract-Increasing the resolution of the reconstructed image in terahertz pulse time-domain holography

Nikolay S. Balbekin, Maksim S. Kulya, Andrey V. Belashov, Andrei Gorodetsky,  Nikolay V. Petrov,

https://www.nature.com/articles/s41598-018-36642-3

In this paper, we present a novel numerical approach for increasing the resolution of retrieved images of objects after their diffraction patterns are recorded via terahertz pulse time-domain holography (THz PTDH). THz PTDH allows for spectrally resolved imaging with high spatial resolution and does not require the fine alignment of complex optics in the THz path. The proposed data post-processing method opens up the possibility to reconstruct holograms recorded with spatially restricted THz detectors, and overcome the diffraction limit even for the lower-frequency spectral components. The method involves an iterative procedure of backward-forward wavefront propagation to simulate the field distribution beyond the initially recorded hologram area. We show significant improvement in both the object reconstruction and contrast across the whole spectrum, with qualitative resolution enhancement at lower frequency spectral components.