Precision Motion Control for Sample Manipulation in Ultra-High Resolution Tomography

In the constantly evolving field of ultra-high resolution tomography, x-rays are used to create nondestructive, high resolution images of a sample at the sub-100 nm level. Precision motion equipment, such as linear and rotation stages, position and manipulate the various elements in a tomography experiment, including the sample that is being imaged, the x-ray beam, and the detector or camera. As x-ray beam cross-sections shrink and detector resolutions improve to nanometer-levels, the positioning performance of the motion equipment must be better than the desired resolution and measurement accuracy. This article will review the motion elements used in a typical synchrotron end station and discuss critical items that designers and engineers must consider when attempting to achieve reliable ultra-high resolution tomography results.

In a synchrotron, the x-rays exit the synchrotron storage ring and enter a beamline. A beamline typically consists of three main areas: the beam conditioning section, sometimes referred to as the optics hutch; the experimental end station, or experimental hutch; and the controls area/cabin where the instrumentation and control systems are located. In the beam conditioning section, the x-ray beam is conditioned to the desired size, shape and wavelength. Devices in this section include shutters, filters, slits, attenuators, collimators, monochromators and focusing mirrors. While high resolution, repeatability, accuracy and stability are necessary characteristics of the motion equipment used to manipulate these devices, the design and selection of those elements are outside the scope of this paper.