The ESA Herschel Telescope Tiger Team metrology review: test results

Doyle, Dominic; Pfund, Johannes; Ninane, Nathalie; Houbrechts, Yvette; Braunecker, Bernhard

doi:10.1117/12.789196

Cited by 2 publications

(2 citation statements)

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“…We must therefore conclude that with this ΔCTE=0.6 ppm/K the discrepancy with the measured ΔBFL=11.7 mm is equal to 3.9 mm. Knowing that the accuracy of the cryo-optical test metrology is equal to ±3.0mm [13] the true discrepancy may be as small as 11.7-3.0-7.8=0.9mm. In any case it can be concluded that the mismatch in the range of 0.9-3.9 mm is well within the minimum instrument focal depth of ±4.3 mm (PACS instrument).…”

Section: Shimming Of Telescope Assemblymentioning

confidence: 98%

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Opto-mechanical modeling of the Herschel Space Telescope at ESA/ESTEC

Fransen¹,

Doyle²

2011

Integrated Modeling of Complex Optomechanical Systems

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In this paper the opto-mechanical modeling of the Herschel infrared space telescope at ESA/ESTEC is presented. The aim of the paper is to give an overview of all modeling activities that took place between 2006 and 2010. In 2006 ESA commissioned a Tiger Team to review the discrepancy between the prediction and measurement of the change in telescope back focal length of the Herschel infrared space telescope. The understanding of the discrepancy was essential since the telescope did not have a refocusing mechanism and hence had to be shimmed to the focus position at cryogenic operational temperature. A team of 16 engineers and scientists collocated at ESA/ESTEC to review the finite element models, optical models and test data used for the prediction of the telescope back focal length. The methodology of prediction, the uncertainties and the obtained results were critically assessed. The team used various modeling techniques including paraxial optical models, first order linear thermal expansion models, full system and metrology ray tracing, deterministic and stochastic thermo-elastic finite element analyses. The opto-mechanical analysis techniques, assumptions and results are discussed. In addition the impact of new measurements of coefficients of thermal expansion, performed after shimming of the telescope flight model, are addressed.

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Section: Shimming Of Telescope Assemblymentioning

confidence: 98%

“…At the end of the Tiger Team activity the telescope was shimmed based on the metrology data which were assessed to be realistic and correct within ±3.0mm (error budget derived for cryo-optical test [13]). The additional shim thickness to be implemented on the spacecraft flight model was set to 8.6 mm.…”

Section: Shimming Of Telescope Assemblymentioning

confidence: 99%