The Advanced Photon Source is currently developing a suite of new hard x-ray beamlines, aimed primarily at the study
of materials and devices under real conditions. One of the flagship beamlines of the APS Upgrade is the In-Situ
Nanoprobe beamline (ISN beamline), which will provide in-situ and operando characterization of advanced energy
materials and devices under change of temperature and gases, under applied fields, in 3D.
The ISN beamline is designed to deliver spatially coherent x-rays with photon energies between 4 keV and 30 keV to the
ISN instrument. As an x-ray source, a revolver-type undulator with two interchangeable magnetic structures,
optimized to provide high brilliance throughout the range of photon energies of 4 keV – 30 keV, will be used. The
ISN instrument will provide a smallest hard x-ray spot of 20 nm using diffractive optics, with sensitivity to sub-10
nm sample structures using coherent diffraction. Using nanofocusing mirrors in Kirkpatrick-Baez geometry, the ISN
will also provide a focus of 50 nm with a flux of 8·1011 Photons/s at a photon energy of 10 keV, several orders of
magnitude larger than what is currently available. This will allow imaging of trace amounts of most elements in the
periodic table, with a sensitivity to well below 100 atoms for most metals in thin samples. It will also enable nanospectroscopic
studies of the chemical state of most materials relevant to energy science. The ISN beamline will be
primarily used to study inorganic and organic photovoltaic systems, advanced batteries and fuel cells, nanoelectronics devices, and materials and systems diesigned to reduce the environmental impact of combustion.
A novel high-resolution x-ray powder diffractometer has been designed and commissioned at the bending magnet
beamline 11-BM at the Advanced Photon Source (APS), Argonne National Laboratory (ANL). This state-of-the-art
instrument is designed to meet challenging mechanical and optical specifications for producing high-quality powder
diffraction data with high throughput. The 2600 mm (H) X 2100 mm (L) X 1700 mm (W) diffractometer consists of
five subassemblies: a customized two-circle goniometer with a 3-D adjustable supporting base; a twelve-channel high-resolution crystal analyzer system with an array of precision x-ray slits; a manipulator system for a twelve scintillator x-ray detectors; a 4-D sample manipulator with cryo-cooling capability; and a robot-based sample exchange automation system.
The mechanical design of the diffractometer as well as the test results of its positioning performance are presented in
Harmonic drive transmissions (HDTs) are compact, low-backlash, high-ratio, high-resolution rotary motion
transmissions. One application to benefit from these attributes is the revolute joint robot. Engineers at the Advanced
Photon Source (APS) are investigating the use of this type of robot for the positioning of an x-ray detector;
understanding the properties of the robot components is crucial to modeling positioner behavior. The robot bearing
elements had been investigated previously, leaving the transmission as the missing component. While the benefits of
HDTs are well known, the disadvantages, including fluctuating dissipation characteristics and nonlinear stiffness, are not
understood as well. These characteristics can contribute uncontrolled dynamics to the overall robot performance. A
dynamometer has been constructed at the APS to experimentally measure the HDT's response. Empirical torque and
position data were recorded for multiple transmission load cases and input conditions. In turn, a computer model of the
dynamometer HDT system was constructed to approximate the observed response.
A novel ultra-high-vacuum (UHV)-compatible x-ray monochromator has been designed and commissioned at the
undulator beamline 8-ID-I at the Advanced Photon Source (APS) for x-ray photon correlation spectroscopy
applications. To meet the challenging stability and x-ray optical requirements, the monochromator integrates two new
precision angular positioning mechanisms into its crystal optics motion control system: An overconstrained weak-link mechanism that enables the positioning of an assembly of two crystals to achieve
the same performance as a single channel-cut crystal, the so called "artificial channel-cut crystal"; A ceramic motor driven in-vacuum sine-bar mechanism for the double crystal combined pitch motion.
The mechanical design of the monochromator, as well as the test results of its positioning performance are presented in
We present design and characterization results of a novel ultra-high-vacuum-compatible artificial channel-cut monochromator that has been installed at the undulator beamline 8-ID-I at the Advanced Photon Source. The monochromator has been designed to meet the challenging stability and optical requirements of the x-ray photon correlation spectroscopy program hosted at this beamline. In particular, the device incorporates a novel in-vacuum sine-bar drive mechanism for the combined pitch motion of the two crystals and a flexure-based high-stiffness weak-link mechanism for fine tuning the pitch and roll of the second crystal relative to the first crystal.
We have developed a prototype instrument with a novel interferometrically controlled differential scanning stage system. The system consists of 9 DC-motor-driven stages, 4 picomotor-driven stages, and 2 PZT-driven stages. A custom-built laser Doppler displacement meter system provides two-dimensional (2D) differential displacement measurement with subnanometer resolution between the zone-plate x-ray optics and the sample holder. The entire scanning system was designed with high stiffness, high repeatability, low drift, flexible scanning schemes, and possibility of fast feedback for differential motion. Designs of the scanning stage system, as well as preliminary mechanical test results, are presented in this paper.
A revolute-joint robot is being developed for the spatial positioning of an x-ray detector at the Advanced Photon Source. Commercially available revolute-joint manipulators do not meet our size, positioning, or payload specifications. One idea being considered is the modification of a commercially available robot, with the goal of improving the repeatability and trajectory accuracy. Theoretical, computational, and experimental procedures are being used to (1) identify, (2) simulate the dynamics of an existing robot system using a multibody approach, and eventually (3) design an improved version, with low dynamic positioning uncertainty. A key aspect of the modeling and performance prediction is accurate stiffness and damping values for the robot joints. This paper discusses the experimental identification of the stiffness and damping parameters for one robot harmonic drive joint.
The Advanced Photon Source (APS) x-ray optics Metrology Laboratory currently operates a small-aperture Wyko laser interferometer in a stitching configuration. While the stitching configuration allows for easier surface characterization of long x-ray substrates and mirrors, the addition of mechanical components for optic element translation can compromise the ultimate measurement performance of the interferometer. A program of experimental vibration measurements, quantifying the laboratory vibration environment and identifying interferometer support-system behavior, has been conducted. Insight gained from the ambient vibration assessment and modal analysis has guided the development of a remediation technique. Discussion of the problem diagnosis and possible solutions are presented in this paper.
This paper profiles the initial phase in the development of a six degree-of-freedom robot, with 1 μm dynamic positioning uncertainty, for the manipulation of x-ray detectors or test specimens at the Advanced Photon Source (APS). While revolute-joint robot manipulators exhibit a smaller footprint along with increased positioning flexibility compared to Cartesian manipulators, commercially available revolute-joint manipulators do not meet our size, positioning, or environmental specifications. Currently, a robot with 20 μm dynamic positioning uncertainty is functioning at the APS for cryogenic crystallography sample pick-and-place operation. Theoretical, computational and experimental procedures are being used to (1) identify and (2) simulate the dynamics of the present robot system using a multibody approach, including the mechanics and control architecture, and eventually to (3) design an improved version with a 1 μm dynamic positioning uncertainty. We expect that the preceding experimental and theoretical techniques will be useful design and analysis tools as multi-degree-of-freedom manipulators become more prevalent on synchrotron beamlines.
High-precision instrumentation, such as that for x-ray diffraction, electron microscopy, scanning probe microscopy, and other optical micropositioning systems, requires the stability that comes from vibration-isolated support structures. Structure-born vibrations impede the acquisition of accurate experimental data through such high-precision instruments. At the Advanced Photon Source, a multiaxis goniometer is installed in the 2-ID-D station for synchrotron microdiffraction investigations. However, ground vibration can excite the kinematic movements of the goniometer linkages, resulting in critically contaminated experimental data. In this paper, the vibration behavior of the goniometer has been considered. Experimental vibration measurements were conducted to define the present vibration levels and determine the threshold sensitivity of the equipment. In addition, experimental modal tests were conducted and used to guide an analytical finite element analysis. Both results were used for finding the best way to reduce the vibration levels and to develop a vibration damping / isolation structure for the 2-ID-D goniometer. The device that was designed and tested could be used to reduce local vibration levels for the vibration isolation of similar high-precision instruments.
System dynamic performance of actuator/stage groups, such as those found in optical instrument positioning systems and other high-precision applications, is dependent upon both individual component behavior and the system configuration. Experimental modal analysis techniques were implemented to determine the six degree of freedom stiffnesses and damping for individual actuator components. These experimental data were then used in a multibody dynamic computer model to investigate the effect of stage group configuration. Running the computer model through the possible stage configurations and observing the predicted vibratory response determined the optimal stage group configuration. Configuration optimization can be performed for any group of stages, provided there is stiffness and damping data available for the constituent pieces.