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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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