%A YAO Chao, CHEN Jianhui, WANG Dong, LI Chunlei
%T Research on probing the transverse coherence of the self-amplified spontaneous emission of a free-electron laser using near-field heterodyne speckle
%0 Journal Article
%D 2018
%J Nuclear Techniques
%R 10.11889/j.0253-3219.2018.hjs.41.100101
%P 100101-100101
%V 41
%N 10
%U {http://www.j.sinap.ac.cn/hjs/CN/abstract/article_1001.shtml}
%8 2018-10-10
%X **[Background]** Coherence is the most striking and fundamental property of the light waves produced by X-ray free-electron lasers (XFEL). The implementation of many experimental techniques exploiting coherent radiation from XFEL requires accurate characterization of spatial properties of the radiation at the sample positon.**[Purpose]** This paper aims to investigate the two-dimensional transverse coherence of the self-amplified spontaneous emission (SASE) of a free-electron laser radiation based on near-field heterodyne speckle.**[Methods]** The laser pulse is irradiated on the nanoparticle solution making Brownian movement to produce near-field heterodyne speckle. Use a splitter to split each single pulse into two equal-amplitude pulses and two statistically independent raw images are obtained simultaneously for accurate extraction of the heterodyne speckle intensity distribution. The square root of the two-dimensional power spatial frequency spectrum of the heterodyne speckle yields the modulus of the complex coherence factor.**[Results]** Theoretical and simulation results proved that the accurate extraction of heterodyne signal and availability of a full two-dimensional coherence map are possible.**[Conclusion]** The above-mentioned method has the capability to probe the real-time coherence property of XFEL photon pulses produced from SASE mode.