Single-shot 2D detector point-spread function analysis employing a circular aperture and a back-projection approach

Knowledge of a detection system's point-spread function (PSF) allows improving image resolution by deconvolving this PSF. The slanted-edge or Siemens-star approaches are commonly used to retrieve the PSF. The latter retrieves the PSF with a poor angular resolution and requires an intricate, sometimes expensive test pattern. The former provides the line-spread function only. Rotating this edge, the PSF could be retrieved in a tedious and time-consuming procedure. Other alternatives are line-pair resolution test charts or point-like light sources, e.g., tiny pinholes or fluorescent beads, which suffer from long acquisition times either due to the need for pattern rotation or very low flux. Here, a single-shot method is presented to retrieve the complete two-dimensional PSF by employing a circular aperture and a back-projection approach similar to computed tomography, which overcomes the issues mentioned above. Additionally, the accuracy of the PSF determination is improved by integrating a sub-pixel-resolution approach. Furthermore, simulations are employed to analyze the method's susceptibility to noise and to assess its intrinsic accuracy. Lastly, an X-ray detector assembly is characterized with this method to showcase the detailed insights into the system's aberrations that can be obtained. Since this technique is not restricted to the X-ray regime, it can be applied to characterize detector systems in other regions of the electromagnetic spectrum. This enables the method's widespread use in the imaging community.