LIGO Document T1000230-v7
- The final design for the Initial Alignment System (IAS) is described in this document. IAS is a component of the Auxiliary Optics System (AOS) for Advanced LIGO (aLIGO). The Initial Alignment System (IAS) comprises the necessary equipment and procedures for setting the initial positions and the angular alignments of all suspended optics, optic tables and for establishing the input laser beam propagation.
N.B.: This document should remain publicly accessible.
- Replaced alignment parameters in Table 5 (which had incorrect pitch angles and was incomplete) with alignment procedure document numbers.
Note: at LHO, in-chamber support tubes were centered in HAM and BSC nozzles for HEPI installation. This meant that ISI position (x,y,z) was subject to small (mm-to-few cm) offsets, owing to *as-built chamber positions*. In certain instances (e.g. WBSC3 ITMX), the offset incurred by the as-built chamber position meant that a SUS position on a given ISI (ITMX quad position, in the WBSC3 chamber example) had to be modified.
Thus, when installation commences for the I1 LIGO India detector, as-built chamber positions *must* be taken into account for IAS assessment of SUS and optic positions.
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