Advanced LIGO subsystems
are the organizational units of the overall project. Follow the links below to view the mission and progress of each subsystem.

Auxiliary Optics Core Optics
Data Acquisition Data and
Input Optics

Advanced LIGO News

Glass Fiber Suspensions Move into Producton

[weld]To reduce thermal noise in the Advanced LIGO interferometers, project personnel will hang certain 40 kg detector mirrors in quadruple suspensions using a quartet of sub-millimeter thickness glass fibers per mirror. The first glass fiber suspension in a production quad underwent assembly at LIGO Hanford in October/November 2011. The act of suspending the optic with glass fibers was the culmination of a long chain of activities such as the bonding of "ears" (for weld points) onto both the mirror and the third-stage glass mass above it. Other steps included the extrusion of tapered 60-cm silica fibers (0.4 mm minumum thickness), and the use of a carbon dioxide laser to perform the welding of the fiber ends onto the upper and lower ears. Precision surveying at the close of the operation revealed that the freely hanging mirror's vertical position was within the 1 mm of the tolerance set by LIGO. The mirror's angle was within the 2 milliradian tolerance level (roughly four hundred-thousandths of a degree).

Glass fiber suspensions originated within the GEO group at the University of Glasgow. The Glasgow group and their counterparts at the University of Birmingham, all members of the LIGO Scientific Collaboration, hold leading responsibility for the delivery of quadruple mirror suspensions in Advanced LIGO. The glass fiber technology that underwent first implementation in the GEO600 detector became a central focus of the suspension groups in LIGO labs at Caltech and MIT during the years leading up to aLIGO construction. MIT's LASTI facility deployed a noise prototype glass fiber quad that served as the predecessor to the production unit shown in these photos. Each of LIGO's three interfemeters will utilize four glass fiber quad suspensions, a requirement that offers a significant schedule challenge for the assembly teams. LIGO suspension personnel on both sides of the Atlantic remain in close contact; members of the UK groups will make a number of visits to LIGO Hanford and LIGO Livingston as the remainder of aLIGO assembly unfolds between 2012 and 2014.

Image 1:  A view of the alignment equipment as seen through the third-stage glass mass

Image 2:  Two completed welds. The metal wires suspend the third-stage mass

Image 3:  The welds must undergo an isopropanol wipe

Image 4:  Fully suspended! The monolith must now be reunited to the reaction chain.

[IAS equipment]
[weld close-up]

[complete hang]


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