Development and implementation of a portable grating interferometer system as a standard tool for testing optics at the APS beamline 1-BM Lahsen Assoufid, 1 Xianbo Shi, 1 Shashidhara Marathe, 1,2 Erika Benda, 1 Michael J. Wojcik, 1 Keenan Lang, 1 Ruqing Xu, 1 Wenjun Liu, 1 Albert T. Macrander, 1 Jon Z. Tischler 1 1 Advanced Photon Source, Argonne National Laboratory, IL 60439 USA 2 Present address: Division of Science, Diamond Light Source Ltd., Didcot, United Kingdom OX11 0DE We developed a portable X-ray grating interferometer setup as a standard tool for testing optics at the Advanced Photon Source (APS) beamline 1-BM. The interferometer can be operated in phase-stepping, Moiré or single-grating harmonic imaging mode with 1-D or 2-D gratings. All of the interferometer motions are motorized; hence it is much easier and quicker to switch between the different modes of operation. A novel aspect of this new instrument is its designed portability. While the setup is designed to be primarily used as a standard tool for testing optics at 1-BM, it could be potentially deployed at other APS beamlines for beam coherence and wavefront characterization or imaging. The design of the interferometer system is described in detail and coherence measurements obtained at the APS 34-ID-E beamline are presented. The coherence was probed in two directions using a 2-D checkerboard, a linear and a circular grating at X-ray energies of 8 keV, 11 keV, and 18 keV. I. INTRODUCTION The emergence of a new generation of powerful X-ray sources such as the future APS Multi-Bend Achromat and hard X-ray free-electron laser sources will provide X-ray beams with high spatial coherence and brightness, which will enable experiments not possible with third-generation storage rings. To take full advantage of the characteristics of these new light sources, the development and availability of coherence- and wavefront-preserving optics are essential. Developing the necessary tools for optics testing and beam wavefront characterization at the operational wavelength is critical to both the optics development process and beamline diagnostics. Many techniques exist for beam wavefront and coherence measurements and characterization [1-7], and each has its own advantages and limitations. Because of the diversity of beam conditions, optical components, and time and space constraints, it is necessary to optimize each method, combine different techniques, or devise new ones. Hence, a dedicated X-ray grating interferometer setup that is portable, versatile and capable of adapting to different techniques was developed and implemented. The interferometer can be operated in phase-stepping, Moiré or single-grating harmonic imaging mode with 1-D or 2-D gratings. All of the interferometer motions are motorized; hence it is much easier and quicker to switch from one mode of X-ray grating interferometer to the other.