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

Development of Input and Recycling Mirror Suspensions Continues

[hsts]Say "suspensions" at LIGO and chances are good that your listener will presume you are making reference to a quadruple suspension. A quad is a four-stage multiple pendulum with a 40 kg Advanced LIGO mirror occupying the lowest stage, hanging from the stage above by four thin glass fibers. LIGO's quad suspensions will hold the four most sensitive mirrors in each interferometer, the mirrors that reflect laser light up and down the 4-kilometer arms. Each detector will contain a number of additional suspended mirrors. Some of these optics will occupy single-stage suspensions in which the mirror rests on a wire loop that fastens directly to the top of the suspension cage. Others are two-stage pendulums (doubles) and others contain three stages (triples). Beam splitters, for instance, will rest at the bottom stage of triple suspensions.

A team at LIGO Livingston (LLO) has worked for several months on the assembly of large and small triple suspensions for optics that will reside between the main laser and the beam splitter and between the beam splitter and a detector's output port. Mirrors slated for these types of suspensions include power recyclers, signal recyclers and mode cleaner optics. The assemblies in these photographs are "dirty." Although prepped and tested in clean room conditions at LLO, the suspensions were constructed of parts that didn't follow the rigorous path of cleaning and baking that's necessary for LIGO's vacuum-rated components. These assemblies will serve as prototypes for testing, evaluation and characterization. Information gathered from these dirty builds will shape the assembly processes that will unfold later at LLO and LHO (LIGO Hanford), yielding production suspensions that will make their way to optical tables inside the vacuum envelopes of the L1, H1 and H2 interferometers.

Image 1:  Two of the assemblers pose with the small triple

Image 2:  A complete small triple with metal masses rather than glass

Image 3:  Installing a stage three mass on a large triple

Image 4:  Aligning a stage three mass on a large triple




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