Table 6
Analyzed and expected sources of focussing and alignment errors.
| Error type | Analyzed | Uncorr. | Corrected | Compensation | See section |
|---|---|---|---|---|---|
| [µm] | [µm] | type | number | ||
| M1 surface RMS HWFE | |||||
| Gravity BUS | Yes | 200 | 5 | LUT/CL | 5.2.1, 5.4.2 |
| Gravity panels | Yes | 8 | 8 | None | 5.2.1 |
| Wind BUS (3.5 m/s) | Yes | 1 | <1 | CL | 5.2.1, 5.4.2 |
| Wind panels (3.5 m/s) | Yes | 1 | 1 | None | 5.2.1 |
| Wind BUS (9 m/s) | Yes | 10 | <10 | CL | 5.2.1 |
| Wind panels (9 m/s) | Yes | 2 | 2 | None | 5.2.1 |
| Thermal BUS (night) | Yes | 12 | 1 | CL | 5.2.1, 5.4.2 |
| Thermal panels (night) | Yes | 2 | 2 | None | 5.2.1 |
| Thermal BUS (day) | Yes | 50 | 5 | CL | 5.2.1, 5.4.2 |
| Thermal panels (day) | Yes | 5 | 5 | None | 5.2.1 |
| M2 surface RMS HWFE | |||||
| Gravity BUS | Yes | 10 | 10 | None | 5.2.2 |
| Gravity panels | No | 2 | 2 | None | 5.2.2 |
| Wind BUS (3.5 m/s) | No | 1 | 1 | None | 5.2.2 |
| Wind panels (3.5 m/s) | No | 1 | 1 | None | 5.2.2 |
| Wind BUS (9 m/s) | No | 7 | 7 | None | 5.2.2 |
| Wind panels (9 m/s) | No | 2 | 2 | None | 5.2.2 |
| Thermal BUS (night) | No | 2 | 2 | None | 5.2.2 |
| Thermal BUS (day) | No | 4 | 4 | None | 5.2.2 |
| Thermal panels (night) | No | 1 | 1 | None | 5.2.2 |
| Thermal panels (day) | No | 5 | 5 | None | 5.2.2 |
| M3 surface RMS HWFE | |||||
| Gravity BUS | No | 3 | 3 | None | 5.2.2 |
| Gravity panels | No | 1 | 1 | None | 5.2.2 |
| Thermal (night) | No | 1 | 1 | None | 5.2.2 |
| Thermal (day) | No | 1 | 1 | None | 5.2.2 |
| Tolerances and alignment | |||||
| Panel manufacturing tolerances | No | 8 | 8 | None | 5.2 |
| Active optical alignment (3.5 m/s) | No | – | 5 | None | 5.2.2, 5.4.2 |
| Active optical alignment (9 m/s) | No | – | 12 | None | 5.2.2, 5.4.2 |
Notes. Overview of analyzed and expected sources of error in the focusing and alignment of the optical surfaces. Analysis here refers to FEA or end-to-end (dynamic state space) modeling. LUT refers to look-up tables (i.e., reproducible values that can be stored in the system and are often appropriate for gross corrections). CL refers to closed-loop corrections expected to rely on metrology and measurements used as feedback in the control system. We note that the error corrections and methods of compensation are based on expectations and requirements that will be further refined as the concept evolves to a construction-ready design. “None” implies that the passive structure provides sufficient performance. We further note that M3 is in the receiver cabin enclosure, so no wind is expected and the thermal deformations are not expected to exhibit strong diurnal variations. Bulk tilts, rotations, and displacements of M2, M3, and the receivers with respect to M1 are not shown here but were considered in the detailed internal error budgets and will be a topic of future study. The values reported in this table supersede those reported in Reichert et al. (2024).
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