Predicted optical performance of the GM/CA@APS micro-focus beamline.
GM/CA at the APS has developed microcrystallography capabilities for structural biology applications. The robust, quad, mini-beam collimators, which enable users to rapidly select between a 5, 10 or 20 micron diameter beam or a scatter guard for the full focused beam, are coupled with several powerful automated software tools that are built into the beamline control system JBluIce-EPICS. Recent successes at beamlines around the world in solving structures from microcrystals (2 - 10 microns) have led to increased demand for high-intensity micro-focus beams. We have designed a new micro-focus endstation to increase the intensity in mini- and micro-beams at GM/CA by one to two orders of magnitude to meet this growing demand. The new optical design is based on the well-established approach of using two-stage demagnification. The existing bimorph mirrors, arranged in a Kirkpatrick-Baez geometry, focus the beam onto slits located upstream of the sample whereby the slit aperture defines a secondary source, that is reimaged with a second pair of mirrors. This design incorporates two focal modes: a mini-beam mode where the beam is focused to 20-micron diameter and a micro-beam mode where it is focused to 5-microns. The size of the secondary source aperture can be varied rapidly (seconds) to adjust the beam size at the sample position in two ranges 20 - 3 micron and 5 - 1 micron. The second set of mirrors will each have two super polished ellipses allowing quick (minutes) interchange between modes.
GM/CA@APS, X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
Robert F
RF
Fischetti
GM/CA@APS, X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
Derek
D
Yoder
GM/CA@APS, X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
Shenglan
S
Xu
GM/CA@APS, X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
Oleg
O
Makarov
GM/CA@APS, X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
Craig
C
Ogata
Life Sciences Institute, Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
Janet L
JL
Smith