document tree node for collecting aLIGO optical layouts at the system level. See individual subsystems for lower-level, subsystem-specific optical layouts.
USEFUL LINKS:
(i) This link includes as-built data and links to specifications and drawings for aLIGO optics: https://galaxy.ligo.caltech.edu/optics/
PENDING:
(i) make T070076 obsolete?
(ii) need a dwg like D0902838 for L1