| Manufacturer | IC Optical Systems |
| Type | ET50 FS |
| Clear aperture (mm) | 50 |
| Plate spacing (mm) | 2.300 (FPI #1), 0.637 (FPI #2) |
| Wedge angle | 20 |
| Coating | Multilayer broadband |
| Dispersion (Å/step) | 4.80 (FPI #1), 4.59 (FPI #2) |
| Wavelength range (Å) | 5800 - 8600 |
| Nominal reflectance (@ 6328 Å) | 0.942 |
| Nominal absorption coefficient |  0.002 |
| Estimated cavity errors | |
| (@ 6328 Å) |  /150 (after coating) |