Spotlight Summary by Jean-Baptiste Masson
Terahertz ptychography
Terahertz (THz) imaging is a challenging field, and in this paper Valzania et al. show that a popular method for X-ray crystallography, namely ptychography, can be an efficient imaging tool using THz radiation. Ptychography is a method, originally conceived by W. Hoppe in the 1960s, which relies on collecting a set of images from the shifted position of an object with a defined coherent beam. Transmission and phase information are found iteratively from the set of recordings. The long wavelength of THz radiation requires the use of Fresnel-Kirchhoff integrals without the usual approximations to model the beam propagation, and the method leads to a lateral resolution of ~2λ and a depth resolution of ~λ/30. The authors demonstrate their approach by imaging various complex shapes and demonstrating similarities between experiments and numerical approaches. Ptychographic THz imaging is significantly slower than holographic imaging, yet it does not require a reference beam and can reconstruct objects larger than the beam diameter. THz ptychography is expected to allow efficient biological sample imaging.
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Article Reference
Terahertz ptychography
- Opt. Lett. 43(3) 543-546 (2018)
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