SDSS-V fiber optic throughput performance evaluation in multi-fiber termination connectors

We present measurements of the adapted SDSS-V BOSS fiber slit, as well as measurements of the APOGEE fiber tributaries in order to better our understanding of throughput loss at multi-fiber termination junctions. The BOSS fiber slit was adapted from the original slit used on sky, and multi fiber termination connectors were added in order to extend the fiber length for the new SDSS-V FPS configuration. Testing on multi fiber termination junctions was conducted with APOGEE tributaries to characterize the expected throughput loss due to multi fiber terminations for the APOGEE spectrograph. Multi fiber connectors were tested with and without index matching gel to evaluate whether throughput loss could be mitigated.