Instrument Disassembly and Packing…July 2015
After successful passage of the Preliminary Acceptance Europe in May, the LN team began the long and complicated task of preparing the instrument for shipment to Arizona.
LINC-NIRVANA will make its way to the LBT in nine, large shipping containers and one oversized box containing the optical bench. In total, some 85 individual crates weighing a total of 37 tonnes will travel by ship from Heidelberg to Rotterdam/Bremerhaven and then across the Atlantic and through the Panama Canal to Los Angeles. From there, a fleet of trucks will transport the precious cargo to the LBT base camp.
The team has planned a sequence of ten re-installation campaigns over the fall and spring months, leading to readiness on the telescope in summer 2016.
The adjacent photographs document some of the packing and shipping effort.
LIFT OFF! (right)- LINC-NIRVANA has "first flight" as the team tests the lifting traverse and other hardware needed for installation at LBT. Click the picture for more details.
Preliminary Acceptance Europe…May 2015
During the first week of May, seven members of the LBT Observatory staff, including the Director, travelled to Heidelberg for the LINC-NIRVANA Preliminary Acceptance Europe (PAE).
After four days of discussion, both the LBTO and LINC-NIRVANA teams were happy to announce successful passage of this important review.
This milestone marks the end of the European portion of the LINC-NIRVANA adventure. In the coming months, the team will complete a few remaining tasks before packing up the instrument and shipping it to the telescope.
Thanks to everyone who made the LN PAE a success!
(right) The happy LBTO and LN teams pose in front of LINC-NIRVANA after the successful completion of Preliminary Acceptance Europe. Click the image for a full-size version.
Full Instrument Flexure Test…April 2015
Unlike most other complex telescope instruments, LINC-NIRVANA must live and work on its host structure, the shared focal platform of the Large Binocular Telescope. This means that, during operation, the instrument must perform to specification over a tip angle of 0° to 70°. It must also survive long periods pointing at the horizon.
Although all of the separate LN systems had been flexure tested individually, it was important to verify that all is well when the entire instrument tips over. During April 2014, the team made multiple flexure tests over the full operating and survival angle range.
Click here to see a video of the flexure test.
(right) LINC-NIRVANA half-way through a tip test. At this stage, the optical bench was fully populated. The brown, steel structure on the left side is a dummy weight to represent the DX Ground-Layer Wavefront Sensor. The actual sensor is at LBT taking part in the Pathfinder experiment. Click the image for full size.
Multi-Tasking in the Lab…October 2014
With all of the LINC-NIRVANA systems coming together, access to the integration lab must be shared by several activities simultaneously.
These activities currently include opt-imization of the SX (left side) warm optics (which were aligned earlier this year – see below), installation of the DX (right side) hardware, and cabling for both the science channel cryostat and the SX Ground-Layer Wavefront sensor.
The optimization activity requires darkened ambient conditions, and hence the team has erected a protective tent over the SX optics. This allows work on other areas to continue unimpeded.
(right) Thomas Bertram (left) checks on the DX fold mirrors, while Tom Herbst (right) examines the output of the wavefront sensor on the darkened SX side.
Luca Marafatto intent in tent.
SX Warm Optics Aligned !
On May 23, The LN team completed the laboratory alignment of the left (SX) half of the LINC-NIRVANA warm optics. This involved adjusting a total of ten lenses, eight mirrors, and a filter to bring the light from the telescope focal plane to the Mid-High Wavefront Sensor (MHWS) with exceptional delivered optical quality.
Congratulations to the bench alignment team, especially Peter Bizenberger, Thomas Bertram, Luca Marafatto, Kalyan Radhakrishnan, Javier Moreno-Ventas, and Matteo Lombini.
Thomas Bertram, Luca Marafatto, and Kalyan Radhakrishnan pose proudly with the optics for which they have just completed the alignment. They are standing at the mount locations of the right (DX) arm of the instrument. The large unoccupied region in the lower middle-right will host the Ground Layer Wavefront Sensor, which is currently at LBT. The image at right shows the optical path.
Light from the telescope enters at lower right and passes through the collimating lenses before bouncing off a flat mirror. The second reflection takes place at the surface of a 349 actuator deformable mirror (with cables) before continuing on to the midline of the instrument. Reflections off the piston mirror and a visible-infrared dichroic send the radiation to the FP20 lens system at upper right. A large field de-rotator precedes a filter and final mirror, which sends the light upward into the wavefront sensor.
Peter Bizenberger working on the alignment of the "K-mirror" field de-rotator. The Mid-High Wavefront Sensor (MHWS) sits to Peter's right.
Interferogram demonstrating that the total wavefront error of the 30 optical surfaces leading to the MHWS is less than 50 nm RMS, a value that is dominated by uncorrected residual error on the deformable mirror.
This animation was captured from the data stream emerging from the Mid-High Wavefront Sensor. The four images result from splitting of the incoming light by small glass pyramids centered on each reference "star" (optical fibers in this lab measurement). The movie begins by demonstrating how subsequent "stars" build up the "meta-pupil" which covers the needed area of higher altitude turbulence. With the three stars in place, the team then adjusted the conjugation altitude of the wavefront sensor. When they overlap, the sensor is focused on ground-layer turbulence. In LINC-NIRVANA, sensing this turbulence is the job of a different wavefront sensor, called the Ground-Layer Wavefront Sensor (GWS). The GWS does not appear in any of these photographs, because it is currently being tested and used on the telescope as part of the Pathfinder experiment (see here).
Second Ground-Layer Wavefront Sensor Delivered!
The second LINC-NIRVANA ground-layer wavefront sensor arrived at MPIA on 17 October. The whole operation went smoothly. In less than four hours, the sensor was unloaded, unpacked, and transported to the lab in the basement of the institute.
Unloading the ground-layer wavefront sensor
from the shipping truck.
Congratulations to the Padova Team for the excellent job they have done in building, testing, and delivering the second GWS!
The slow and careful “funeral processioon”
to transport the sensor to the lab.
FFTS Cold Initial Testing - March 2013
The Cologne FFTS team were at MPIA in March 2013 to test fit and cool the Fringe and Flexure Tracking System in the LINC-NIRVANA cryostat.
Site manager: Tom Herbst
14 July 2015