Design optimization of a periodic microstructured array anode for hard x-ray grating interferometry.

Talbot-Lau grating interferometer (TLGI) has great advantages in x-ray imaging contrasts, especially for low-Z materials, over conventional absorption contrast. A microstructured array anode target (MAAT) source offers significantly higher imaging throughput than the combination of an extended x-ray source paired with an absorption grating (also known as source grating). The performance of the MAAT source can be optimized with respect to the areal density, dimensions, and choice of material for the microstructured metal inserts (MMI) and the substrate in which they are embedded. In this paper, we analyze the x-ray generation efficiency per incident electron, relative fraction of x-rays generated by MMI and substrate, x-ray spectrum, and angular distribution via Monte Carlo simulation. Based on the simulation results, the optimal parameters are obtained for a MAAT with incident electron energies from 30 keV to 120 keV. The corresponding temperature distribution within the MAAT is also simulated for the optimal set of the parameters via finite element analysis. As demonstrated by the thermal analysis data, the maximum allowable electron-beam power loading was derived that allows a stable operation of the transmission MAAT.

Assessing and optimizing the performance of a phase-shifting interferometer capable of measuring the complex index of refraction and the surface profile of a test surface.

A novel interferometer based upon a conventional phase-shifting design is further investigated. This interferometer is capable of measuring both the real and imaginary parts of the complex index of refraction and the surface profile of a test surface. Maximum-likelihood estimation theory is shown to be an effective means of extracting the three parameters of interest from the measured data. Cramér-Rao lower bounds are introduced as a means of quantitatively assessing the performance of the system. Furthermore, it is shown that as the design parameters are optimized, the results approach the theoretical performance limit. We conclude by developing the underlying theory behind the relationship of the complex-index-of-refraction estimates to the surface-profile estimate.