Though the majority of the actual beam combining and beat note detection takes place within fiber coupled components, and therefore needn't take up much, or any, space on the actual PSL table, we still need to efficiently couple PSL light into fibers in order to act as the second signal to be beat against the AUX light.
The constraints we must take into account are the same as when coupling AUX light to fibers:
a) We need to think of the saturation power of the photodiode we will be using, and attenuate accordingly.
b) Given this constraint upon our system, we need to think about the space available to us of the PSL table.
c) Finally, we need to design a third telescope (in addition to those coupling the AUX light) to couple PSL light into fibers.
The rest of the beat note setup, i.e. beam combiners and photodiodes, will all be located within fibers, and so don't actually need to be located on an optical table.
Once the setup near the vertex of the interferometer is complete, all that remains to be done is testing, and implementation.