Figure 7
Simulated ID spectra and Stokes parameters for circularly polarized SR light (hν ≈ 400 eV) emitted from two ID segments (ID × 2; a, d), four ID segments (ID × 4; b, e) and eight ID segments (ID × 8; c, f). The normalized Stokes parameters S1 (linear polarization; PL), S2 (linear polarization in a plane rotated by 45° with respect to S1 plane; PL45) and S3 (circular polarization; PC) are derived. In the simulation using SPECTRA, the distance between the light source point and the front-end slit was fixed at 44 m, and the opening size of the front-end slit was 0.5 mm × 0.5 mm; the ID segments were adjusted so that the side peak of the ID spectrum was located at 398 eV, and the phase shifters were set to produce the circular polarization. One should notice that the helicity of the circular polarization (i.e. the sign of S3) is opposite between the main peak and the side peak of the ID spectra. |