ANL, Lemont, Illinois, USA
An electronic autocollimator is a valuable tool that can assist in the alignment of optical beamline components such as mirrors and monochromators. It is also a powerful tool for in situ diagnoses of the mechanical behavior of such components. This can include the repeatability of crystals, gratings, and mirrors as they are rotated; the parasitic errors of these same optical elements as they are rotated and/or translated; and the repeatability and parasitic errors as bendable mirrors are actuated. The autocollimator can even be used to establish a secondary reference if such components require servicing. This paper will provide examples of such alignments, diagnoses, and references that have been made with an autocollimator on existing and recently commissioned beam-lines at the Advanced Photon Source (APS). In addition, this paper will discuss how this experience influenced the specifications and subsequent designs of the new primary high-heat-load mirror systems (PHHLMS) that are currently under fabrication for six of the APS Up-grade (APS-U) feature beamlines. Each mirror was specified to provide in situ line-of-sight access for an autocollimator to either the center of the mirror’s optical surface or to a smaller polished surface centered on the backside of each mirror substrate. This line of sight will be used for initial alignment of the mirror and will be available for in situ diagnoses if required in the future.
ANL, Lemont, Illinois, USA
The X-ray Photon Correlation Spectroscopy (XPCS) beamline at the Advanced Photon Source (APS) has been selected as one of the nine feature beamlines being de-signed to take advantage of the increase in coherent flux provided by the APS Upgrade. The 8-ID-E enclosure at the beamline will have a dedicated instrument for per-forming Wide Angle XPCS (WA-XPCS) measurements across a range of length and time scales. The instrument will feature a high-stability 6-circle diffractometer, a moveable Long Distance Detector Positioner (LDDP) for positioning a large pixel array detector, and a removable flight path assembly. For intermediate sample to detector distances of 1.5 to 2 meters, a large pixel array detector will be positioned on the diffractometer detector arm. For longer sample to detector distances up to 4 meters, an horizontal scattering geometry will be utilized based on the LDDP to position a second large pixel array detector. The LDDP will consist of a large granite base on which sits a combination of motorized stages. The base will sit on air casters that allow the LDDP to be coarsely posi-tioned manually within the enclosure. Final positioning of the detector will be achieved with the mounted stages. The spatial relationship between the sample and the free moving LDDP will be monitored using a laser tracking system. A moveable flight path will be supported by the diffractometer arm and a mobile floor support to mini-mize air scattering while using the LDDP. The WA-XPCS instrument has been designed with users and beamline staff in mind and will allow them to efficiently utilize the highly enhanced coherent beam provided by the APS Upgrade.