Extreme ultraviolet (EUV) lithography at a wavelength of 13.5 nm is expected to be the promising technology for semiconductor manufacturing aimed at a node size of the dynamic random-access memory (DRAM) half pitch below 20 nm.Laser-produced Sn plasma is an attractive EUV light source.The plasma is expected to have a high electron density (ne =1024-1025 m-3) and moderate electron temperature (Te =30-50 eV)[1].In order to optimize the plasma,precise measurements of these plasma parameters with sufficient spatial and temporal resolutions are required.