Operando measurement of lattice deformation profiles of synchrotron radiation monochromator

This study presents a new method for characterizing the thermal lattice deformation of a monochromator with high precision under service conditions and first reports the operando measurements of nanoscale thermal lattice deformation on a double-crystal monochromator at different incident powers. The nanoscale thermal lattice deformation of the monochromator first crystal was obtained by analyzing the intensity of the distorted DuMond diagrams. DuMond diagrams of the 333 diffraction index, sensitive to lattice deformation, were obtained directly using a 2D detector and an analyzer crystal orthogonal to the monochromator. With increasing incident power and power density, the maximum height of the lattice deformation increased from 3.2 to 18.5 nm, and the deformation coefficient of the maximum height increased from 1.1 to 3.2 nm/W. The maximum relative standard deviation was 4.2 \(\%\) $\%$ , and the maximum standard deviation was 0.1 nm. Based on the measured thermal deformations, the flux saturation phenomenon and critical point for the linear operation of the monochromator were predicted with increasing incident power. This study provides a simple solution to the problem of the lower precision of synchrotron radiation monochromator characterizations compared to simulations.