ATTENZIONE! IL REPOSITORY E’ APERTO ESCLUSIVAMENTE ALL’IMMISSIONE DEI RAPPORTI TECNICI (COLLEZIONE 4.01). NON E’ POSSIBILE INSERIRE PRODOTTI IN TUTTE LE ALTRE COLLEZIONI, A CAUSA DI PROBLEMI TECNICI. THE REPOSITORY IS OPEN EXCLUSIVELY FOR THE SUBMISSION OF TECHNICAL REPORTS (COLLECTION 4.01). SUBMISSIONS TO ALL OTHER COLLECTIONS ARE TEMPORARILY UNAVAILABLE, DUE TO TECHNICAL ISSUES.
 

The crystal ball, the spider and other stories: a journey around the test tower of the M4 adaptive mirror

Date Issued
2018
Author(s)
•
•
•
•
Rossetti, Marco
•
•
DOI
Abstract
M4 is the adaptive mirror of ELT, currently at its FDR. It is composed by 6 thin shell mirror segments, controlled by 5136 voice coil actuators. Before its installation at the telescope, it will be optically calibrated on a test facility (OTT) in Italy. The calibration includes the computation of the flattening command and the segments co-phasing, i.e. the correction of the differential piston amongst them. Given the large complexity of the deformable mirror and the very tight requests on the measurement accuracy, we set-up a risk-mitigation activity based on the laboratory demonstration of some key elements within the test tower. In this paper we present the results of the experimentation. We measured at nanometer level the interferometric cavity; we investigated how the interferometer reacts in presence of spider arms dividing the test mirror into separated islands; we integrated and tested a multi wavelength sensor to measure the inter-segment absolute differential piston; we aligned and tested for stability the pupil relaying optical system to be installed on the OTT. Such activity is performed in the AO laboratory at INAF-Arcetri in Italy, in preparation of the M4 optical calibration on the OTT, scheduled to start in 2020. The M4 project is led by the Italian consortium AdOptica under an ESO contract.
Coverage
Adaptive Optics Systems VI
All editors
Close, Laird M.; Schreiber, Laura; Schmidt, Dirk
Series
Volume
10703
Start page
1070373
Conferenece
Adaptive Optics Systems VI
Conferenece place
Austin, Texas, United States
Conferenece date
10-15 June, 2018
Uri
Url
Issn Identifier
0277-786X
Ads BibCode
2018SPIE10703E..73B
Rights
open.access
File(s)
Loading...
Thumbnail Image
Name

1070373.pdf

Description
Pdf editoriale
Size

2.63 MB

Format

Adobe PDF

Checksum (MD5)

c12d3f065ba3b6187315effc93142847