Fig. 3: Imaging of non-transparent sample using nonparaxial Airy beam.
From: Terahertz structured light: nonparaxial Airy imaging using silicon diffractive optics
Image of the target with different period slits (a). Performance of the nonparaxial Airy phase mask in THz imaging in two setups: with a single nonparaxial zone plate (b) and two nonparaxial zone plates (c). T indicates the imaged target. The color bar is normalized to the maximal value of the signal. Z1 and Z2 indicate distances between optical elements and the object. The first row on the right and the second row on the right present comparison of the experimentally obtained and numerically calculated object pictures for both setups, respectively. Cross-sections of the imaged objects (at positions denoted by dashed lines) are depicted in graphs (d) for setup with an Airy lens and a single nonparaxial zone plate and (e) for an Airy lens and two nonparaxial zone plates. Cross-sections of the recorded image (d) proving the 3.2 λ spacial resolution with more distorted target bars image; Cross-sections of the recorded image (e) with precise spatial frequency resolution reaching 1.6 λ with the contrast of 2 (a.u.)
