Related Experiment Video
Updated: Jan 28, 2026

Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating
Published on: October 11, 2016
Coherence and pulse duration characterization of the PAL-XFEL in the hard X-ray regime
Kyuseok Yun1, Sungwon Kim1, Dongjin Kim1
1Department of Physics, Sogang University, Seoul, 04107, Korea.
Abstract:
We characterize the spatial and temporal coherence properties of hard X-ray pulses from the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL, Pohang, Korea). The measurement of the single-shot speckle contrast, together with the introduction of corrections considering experimental conditions, allows obtaining an intrinsic degree of transverse coherence of 0.85 ± 0.06. In the Self-Amplified Spontaneous Emission regime, the analysis of the intensity distribution of X-ray pulses also provides an estimate for the number of longitudinal modes. For monochromatic and pink (i.e. natural bandwidth provided by the first harmonic of the undulator) beams, we observe that the number of temporal modes is 6.0 ± 0.4 and 90.0 ± 7.2, respectively. Assuming a coherence time of 2.06 fs and 0.14 fs for the monochromatic and pink beam respectively, we estimate an average X-ray pulse duration of 12.6 ± 1.0 fs.
Related Concept Videos
X-ray Crystallography
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
Pulse
The pulse serves as a clinical...
Pulse
Pulse Rate and its Significance
Pulse rate, often measured in beats per minute (bpm), reflects the heart rate (HR), which is influenced by numerous factors such as stress, physical activity, and hormonal changes. A normal resting adult pulse rate falls...
Toughness and Hardness of Aggregate
NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
Pulse Oximetry
Purpose
Average SpO2 values are greater than 95%. If the readings fall below 90%, it indicates that...

