Fig. 1
From: Advancing X-ray quantum imaging through Monte-Carlo simulations
(A) Schematic representation of the optical setup used for the generation of SPDC and XQI. An X-ray beam (red line) travels through two slits before hitting a diamond crystal which splits the photon into two photons. The biphotons propagate towards the detector (pink and yellow cones and dots). Some of the photons hit the sample while others go directly to the detector. A circular beam stop (BS) centered at the Bragg angle was used in front of the detector. (B) A schematic representation of the momentum space for the down-conversion process. \(\:{\mathbf{K}}_{p}\), \(\:{\mathbf{K}}_{s}\), and \(\:{\mathbf{K}}_{i}\) are the pump, signal, and idler wave vectors, respectively. \(\:\mathbf{G}\) is the reciprocal lattice vector, and \(\:{\alpha}_{s}\) / \(\:{\alpha}_{i}\) are the angles between signal/idler photon wave vectors and \(\:{\mathbf{K}}_{p}+\mathbf{G}\) (dark green arrow). \(\:{\theta}_{B}\) and \(\:{\Delta}\theta\:\) are the Bragg and detuning angles, respectively. The inset shows the detected image of the SPDC with circles representing the biphoton probable location at a fixed energy ratio with dot presenting an example of such photon pair. The biphotons are collinear with the beam center and positioned diametrically opposite.
