A variety of approaches are used to investigate interstellar and intergalactic magnetic fields these fields. Observational results of these magnetic fields are reviewed: The large-scale magnetic fields in the Milky Way have been best probed by Faraday rotation measures of a large number of pulsars and extragalactic radio sources. The coherent Galactic magnetic fields are found to follow the spiral arms and have their direction reversals in arms and interarm regions in the disk. The azimuthal fields in the halo reverse their directions below and above the Galactic plane; The orientations of organized magnetic fields in nearby galaxies have been observed through polarized synchrotron emission. Magnetic fields in the intracluster medium have been indicated by diffuse radio halos, polarized radio relics, and Faraday rotations of embedded radio galaxies and background sources. Future observational perspectives are given to reveal the 3D
tomography of the large-scale coherent magnetic fields in our Galaxy and nearby galaxies, a better description of intracluster field properties, and firm detections of intergalactic magnetic fields in the cosmic web.
 J. L. Han, Annual Review of Astronomy and Astrophysics 55, 111 (2017)
 J. L. Han, R. N. Manchester, W. van Straten, P. Demorest, ApJS 234, 11 (2018)
 J. Xu & J.L. Han, MNRAS 486, 4275 (2019)
Prof. JinLin Han is a world famous expert on the observations of interstellar and intergalactic magnetic fields. He obtained the Bachelor degree of Engineering in 1986 from Southeast University (Nanjing Institute of Technology), and then went to Shanghai Observatory, Chinese Academy of Science to make his Master degree of Science. In 1989, he moved to Beijing Astronomical Observatory, Chinese Academy of Sciences to be a PhD student, and got PhD degree in 1993. Since then he has been working on the
National Astronomical Observatories of CAS. He started to work on magnetic fields of galaxies in the last year of PhD. He is the first person who figure out the parity of magnetic field configurations in galaxies, and he measured the large-scale magnetic fields in the Galactic plane for more than 20 years. He obtained the first and even still state-of-art spatial magnetic energy spectrum of the interstellar magnetic fields. His results are crucially important for the theoretical investigations of the origin and evolution of the magnetic fields in the galaxies and fundamental for the particle physics or cosmic rays.