RESUMO
The shapes of light sources such as electron beams can be reconstructed by inverse Fourier transformation of the complex degree of spatial coherency, which can be measured using Young's interferometer. The application of the phase-retrieval algorithm to reduce phase measurement errors in the complex degree of spatial coherency is numerically studied using an electron beam with an asymmetric distribution. This application is demonstrated with experimental data measured at the diagnostic beamline at the Pohang Accelerator Laboratory.
RESUMO
The coherency of the synchrotron radiation at Pohang Accelerator Laboratory has been investigated using Young's interferometer. The electron beam size can be measured precisely using the interferometer. An interferogram using 650 nm light at the diagnostics beamline at Pohang Light Source (PLS) has been measured to determine the electron beam distribution and the spatial coherence length. Interferograms obtained by numerical study are compared with experimental results in order to understand the measured data. From this comparison, the electron beam at PLS is revealed to be a Gaussian distribution with a standard deviation of 210 microm. The spatial coherency length of 650 nm light at PLS is measured to be 0.57 cm, and that of 0.1 nm light at PLS is predicted to be 0.88 microm by the same numerical study.
RESUMO
We developed an off-axis-illuminated zone-plate-based hard x-ray Zernike phase-contrast microscope beamline at Pohang Light Source. Owing to condenser optics-free and off-axis illumination, a large field of view was achieved. The pinhole-type Zernike phase plate affords high-contrast images of a cell with minimal artifacts such as the shade-off and halo effects. The setup, including the optics and the alignment, is simple and easy, and allows faster and easier imaging of large bio-samples.