Table 5. List of all gratings in the I21 SGM after the sample position.
| Spectrometer grating | SVLS1 | SVLS2 | SVLS3 |
|---|---|---|---|
| Ruled area (mm) | 190 × 30 | 190 × 30 | 160 × 28.7 |
| Blaze angle (°) | – | – | 0.68 |
| Apex angle (°) | – | – | 176.6 |
| Groove width-to-period ratio | 0.68 | 0.60 | – |
| Groove depth (nm) | 7.8 | 5.24 | – |
| Coating thickness (nm) | 30 (Au) | 30 (Pt) | 30 (Pt) |
| Roughness (Å, r.m.s.) | 1.80 | 0.25 | 0.167 |
| Substrate material | Fused silica | Fused silica | Silicon |
| Tangential slope error (µrad, r.m.s.) | 0.136 | 0.090 | 0.101 |
| a 0 (l/mm) | 1500.286 | 2699.6 | 1500.017 |
| a 1 (l/mm2) | 7.564 × 10−2 | 0.1584 | −4.522 × 10−2 |
| a 2 (l/mm3) | −1.139 × 10−4 | −1.881 × 10−4 | −4.123 × 10−4 |
| a 3 (l/mm4) | 5.528 × 10−8 | 1.14 × 10−7 | 3.4 × 10−7 |
| Tangential radius (m) | 94.51 | 94.36 | 115.8004 |
| Manufacturer | JTEC and Shimadzu | JTEC and HORIBA | JTEC and HZB |