Alignment techniques for calibration and installation of a 6-m Toroidal Grating Monochromator

Abstract

The University of Wisconsin Synchrotron Radiation Center Optics Group has recently completed the installation of three 6-m Toroidal Grating Monochromator (TGM) beamlines on the Aladdin ring. Two of these beamlines image bending-magnet radiation and the third images radiation from the 30-period undulator on loan to the Synchrotron Radiation Center from the Stanford Synchrotron Radiation Laboratory and Lawrence Berkeley Laboratory. Each beamline required an accurate alignment strategy. This is due to the long source-to-final-image distance and the five independent critical elements: entrance mirror, entrance slit, grating chamber, exit slit, and exit mirror. The TGM grating chamber houses up to six gratings on a revolving carousel which is scanned with a sine-drive. We will describe grating stability checks and adjustments to linearize the grating scan calibration. We will also outline the basic alignment procedures from the source point, through the grating chamber, to the final focus. The procedure we have used provided sufficiently accurate alignment to realize the high throughput and resolution capabilities of the 6-m TGMs. The methods also allow later checks on critical degrees of freedom of the optical components.