J. Synchrotron Rad. 10 (2003) 125-136
Interferometer-controlled scanning transmission X-raymicroscopes at the Advanced Light Source
A. L. D. Kilcoyne (a), T. Tyliszczak,(b,c) W. F. Steele,(c) S. Fakra,(c) P. Hitchcock, (b) K. Franck, (c) E. Anderson,(d) B. Harteneck,(d) E. G. Rightor,(e) G. E. Mitchell,(e) A. P. Hitchcock,(b) L. Yang,(b) T. Warwick,(c) and H. Ade(a)*
a Department of Physics, North Carolina State University, Raleigh, NC 27895,
b Brockhouse Institute for Material Research, McMaster University, Hamilton, ON L8S 4M1, Canada
c Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
d Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
e Dow Chemical, 1897 Bldg, Midland, MI 48667, USA.
(Received 21 Jan 2003; accepted 25 Feb 2003)
Two new soft X-ray scanning transmission microscopes located at the Advanced Light Source (ALS) have been designed, built and commissioned. Interferometer control implemented in both microscopes allows the precise measurement of the transverse position of the zone plate relative to the sample. Long-term positional stability and compensation for transverse displacement during translations of the zone plate have been achieved. The interferometer also provides low-distortion orthogonal x, y imaging. Two different control systems have been developed: a digital control system using standard VXI components at beamline 7.0, and a custom feedback system based on PC AT boards at beamline 5.3.2. Both microscopes are diffraction limited with the resolution set by the quality of the zone plates. Periodic features with 30 nm half period can be resolved with a zone plate that has a 40 nm outermost zone width. One microscope is operating at an undulator beamline (7.0), while the other is operating at a novel dedicated bending-magnet beamline (5.3.2), which is designed specifically to illuminate the microscope. The undulator beamline provides count rates of the order of tens of MHz at highenergy resolution with photon energies of up to about 1000 eV. Although the brightness of a bending-magnet source is about four orders of magnitude smaller than that of an undulator source, photon statistics limited operation with intensities in excess of 3 MHz has been achieved at high energy resolution and high spatial resolution. The design and performance of these microscopes are described.
Keywords: X-rays; zone plates; scanning microscopy; NEXAFS.
@2002 International Union of Crystallography