  The development of bare fiber or air-gapped microlens-fiber coupled Integral
Field Units (IFUs) for astronomical applications requires careful treatment of
the fiber end-faces (terminations). Previous studies suggest that minimization
of fiber end face irregularity leads to better optical performance in terms of
the diminishing effect of focal ratio degradation. Polishing has typically been
performed using commercial rotary polishers with multiple gradually decreasing
grit sizes. These polishers generally lack the ability to carefully adjust
angular position and polishing force. Control of these parameters vastly help
in getting a repeatable and controllable polish over a variety of
glass/epoxy/metal matrices that make up integral filed units and fiber slits. A
polishing arm is developed to polish the fiber terminations (IFU, mini-bundles
and v-grooves) of the NIR Fiber System for the RSS spectrograph at SALT. The
polishing arm angular adjustments ensure the correct position and orientation
of each termination on the polishing surface during the polish. Various studies
have indicated that the fiber focal ratio also degrades if the fiber end face
comes under excessive stress. The polishing arm is fitted with a load cell to
enable control of the polishing force. We have explored the minimal applicable
end stress by applying different loads while polishing. The arm is modular to
hold a variety of fiber termination styles. The polishing arm is also designed
to access a fiber inspection microscope without removing the fiber termination
from the arm. This enables inspection of the finish quality at various stages
through polishing process.
