Metrology of a mirror at the Advanced Photon Source:
comparison between optical and x-ray measurements
Lahsen Assoufid, Jonathan Lang, Jin Wang, and George Srajer (
Advanced Photon Source
Argonne National Laboratory
9700 South Cass Avenue, Argonne, Illinois 60439, USA
ABSTRACT                                       C
This paper describes metrology of a vertically focusing mirror on the bending magnet beamline in sector-1
of the Advanced Photon Source, Argonne National Laboratory. The mirror was evaluated using
measurements from both an optical long trace profiler and x-rays. Slope error profiles obtained with the two
methods were compared and were found to be in a good agreement. Further comparisons were made between
x-ray measurements and results from the SHADOW ray-tracing code.
Keywords: long trace profiler, metrology, x-ray mirror, synchrotron radiation
1. INTRODUCTION
The performance of grazing-incidence mirrors used on beamlines at third-generation synchrotron
radiation sources depends considerably on the magnitude of large scale irregularities (figure error) as well as
on the smoothness (microroughness or finish) of their reflecting surfaces. Typically, surfaces slope errors
and roughnesses better than 3 prad and 3 A rms, respectively, are required in order to preserve the brilliance
of these sources. Considering the high cost of mirrors and their long delivery time, it is important to
evaluate their optical quality upon the delivery from the manufacturer as part of the acceptance criteria. At
the Advanced Photon Source (APS), this is normally done using optical interferometers available at the
metrology laboratory. Furthermore, state-of-the-art optical metrology instruments have adequate sensitivity
and cover a wide range of spatial frequencies to provide the user with useful information in order to predict
the performance of optics. However, the ultimate tests are those performed at, or near, wavelengths at
which the optic is intended to operate.                                      The submitted manuscript has

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