Using multifield measurements to eliminate alignment degeneracies in the JWST testbed telescope

Erin Sabatke; Scott Acton; John Schwenker; Tim Towell; Larkin Carey; Duncan Shields; Adam Contos; Doug Leviton

doi:10.1117/12.736309

20 September 2007 Using multifield measurements to eliminate alignment degeneracies in the JWST testbed telescope

Erin Sabatke, Scott Acton, John Schwenker, Tim Towell, Larkin Carey, Duncan Shields, Adam Contos, Doug Leviton

Proceedings Volume 6687, UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts III; 668707 (2007) https://doi.org/10.1117/12.736309
Event: Optical Engineering + Applications, 2007, San Diego, California, United States

Abstract

The primary mirror of the James Webb Space Telescope (JWST) consists of 18 segments and is 6.6 meters in diameter. A sequence of commissioning steps is carried out at a single field point to align the segments. At that single field point, though, the segmented primary mirror can compensate for aberrations caused by misalignments of the remaining mirrors. The misalignments can be detected in the wavefronts of off-axis field points. The Multifield (MF) step in the commissioning process surveys five field points and uses a simple matrix multiplication to calculate corrected positions for the secondary and primary mirrors. A demonstration of the Multifield process was carried out on the JWST Testbed Telescope (TBT). The results show that the Multifield algorithm is capable of reducing the field dependency of the TBT to about 20 nm RMS, relative to the TBT design nominal field dependency.

Citation Download Citation

Erin Sabatke, Scott Acton, John Schwenker, Tim Towell, Larkin Carey, Duncan Shields, Adam Contos, and Doug Leviton "Using multifield measurements to eliminate alignment degeneracies in the JWST testbed telescope", Proc. SPIE 6687, UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts III, 668707 (20 September 2007); https://doi.org/10.1117/12.736309

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