25A Coherent X-ray Scattering

Scientific Scope

The highly coherent beam and the design of the end-station will provide users to perform X-ray Photon Correlation Spectroscopy (XPCS) and Coherent Diffraction Imaging (CDI) experiments. A main advantage of XPCS is the possibility to study the dynamics of a multitude of collective processes such as diffusion of colloids, complex Fluids, polymer blends, clays, capillary fluctuation, liquid crystal membranes, non-equilibrium dynamics, binary alloys, metal/polymer nano-composite, and charge-, spin-, orbital-, ordered domains. The diffraction patterns of the specimens are collected as the coherent X-ray illuminating on and through the phase retrieval algorithms the real-space images of the specimens are reconstructed from the coherent diffraction patterns with real-space support. For the scanning-type CDI, ptychography, the overlapped regions in the neighboring scan are employed to be the real-space support.

Beamline Description

CXS beamline with the windowless design keeps the coherence of the X-ray photon beam. The two step focusing configuration in horizontal and two switchable optics, VCRL and VFM, in vertical achieve that the beam size can be changed in 1 μm2 and 100 μm2. The sample to detector distance is varied in the range of 0.7 to 12 m, so the q-range covers from 0.0002 to 3 Å-1. A photon-counting area detector, Eiger X 16M, is also equipped with the frame rate of 133 Hz. A flexible sample environment would meet the requirements of users.

Photon Source

The CXS beamline is located at the port 25 of TPS. The port 25 is an output port of a 12-meter long straight section where two IU22 undulators, a 3 meter-long IU22 undulator and a 2 meter-long IU22 undulator, are installed. at a long straight section. The photon source of CXS beamline is irradiated from the two in-vacuums undulators IU22, which provide the X-rays beam with the energy range from 5.56 to 20 keV, based on the 3rd, 5th, 7th, 9th, or 11th harmonic of IU22.

ID 3m    ID 2m

Fig. 1. The 3-meter long IU22 (right) and the 2-meter long IU22 (left)

The estimated photon flux, brilliance and coherent photon flux are shown as the following figures.



C flux

Beamline Device

  • Differential Pumping System
    The differential pumping system is designed to protect the front end for the windowless setup.

          DF system

  • Double Crystal Monochromator (DCM)
    The DCM with two switchable crystal sets for the high flux mode and high energy resolution mode operating. In each crystal holder there are two crystals mounted and by using a lateral translation the crystals can be switched.

          DCM_1               DCM crystal

  • 1st Focusing System
    The Vertical Compound Refractive lenses (VCRL) and the 1st Horizontal Focusing Mirror (HFM1) are mounted with the 1st Focusing System. The VCRL is used to focus the X-ray photon beam on the sample position with the beam size of 10 μm in vertical. In horizontal the two step focusing configuration is employed. The focal point of the HFM1 is on the Horizontal Secondary Source (HSS) slit and the horizontal beam size on the sample can be varied by the opening of the HSS slit.

          1st focusing

          HFM1 VCRL

  • 2nd Focusing System
    The 2nd Focusing System hosts the Vertical Focusing Mirror/Vertical Deflective Mirror (VFM/VDM) and the 2nd Horizontal Focusing Mirror (HFM2). The VFM and VDM is installed on the sample mirror mount. With a long lateral translation the VFM and VDM can be switched to collocate the upstream optics and with different setup the photon path is kept the same. The mechanism for mirror adjustment has three in-air jacks and two in-vacuum translations.

          2nd focusing  KB

Find a Beamline

25A Home




BL Schedule

Optical Layout



Other BL Info



BL Spokesperson

—Yu-Shan Huang (黃玉山)
Ext. 7332
Mobile: +886-912536463

BL Local Contact/Manger

Jhih-Min Lin (林智敏)
Ext. 7342
Mobile: +886-938114881


  • Coherent Diffraction Imaging (CDI)
  • X-ray Photon Correlation Spectroscopy (XPCS)
  • Small Angle X-ray Scattering (SAXS)


  • Materials science
  • Polymer and soft matter
  • Nanotechnology

General Information

  • Source: 25A
  • Energy Range: 5.5-20 keV
  • Focused Spot Size: 1 x 1 μm² or 10 x 10 μm²
  • Status: operational

National Synchrotron Radiation Research Center

101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu, Taiwan 30076