Speaker
Description
Beam-modulation techniques in X-ray imaging can serve for disentangling different contrast modalities, such as absorption, phase, and dark-field contrast. These encompass Talbot-grating interferometry of shadow mask (Hartmann) techniques. We have devised micro-lens arrays to be used as Shack Hartmann masks for dose-efficient, single-exposure imaging of dynamic processes.
The Shack-Hartmann mask consists of a 2D array of microlenses that partition a wide X-ray beam into individual beamlets, whose attenuation, deviation and broadening will reflect sample properties like absorption, phase shift and scattering power, respectively. Thus, an efficient use of the incoming X-ray flux is made, which allows reducing exposure times down to few micro-seconds. This approach was used to image the structure formation process during pulsed laser ablation in liquids (PLAL). PLAL is a procedure to produce nanoparticles suspended in liquids by ablating a target with an intense pulsed laser beam. The product relies on an intricate interplay between different length and time scales.
We will show that different lens arrays as a 3D-printed crossed cylinder lens array (SHARX [1]) or a compound lens array (CARL [2]) of structured polyimide foils are capable of delivering in-formation on macroscopic dynamics as well as the occurrence of nanoparticulate mass during the process.
- T. dos Santos Rolo, S. Reich, D. Karpov, S. Gasilov, D. Kunka, T. Baumbach, A. Plech: A Shack-Hartmann sensor for single-shot multi-contrast imaging with hard X-rays, arXiv: 1802.10045 (2018).
- S. Reich, T. dos Santos Rolo, A. Letzel, T. Baumbach, A. Plech: Scalable, large area compound array refractive lens for hard X-rays, Appl. Phys. Lett. 112, 151903 (2018)
