  BIFROST will be a short-wavelength ($\lambda$ = 1.0 - 1.7$\mu$m) beam
combiner for the VLT Interferometer, combining both high spatial ($\lambda$/2B
= 0.8 mas) and spectral (up to R = 25,000) resolution. It will be part of the
Asgard Suite of visitor instruments. The new window of high spectral
resolution, short wavelength observations brings with it new challenges. Here
we outline the instrumental design of BIFROST, highlighting which beam combiner
subsystems are required and why. This is followed by a comparison All-In-One
(AIO) beam combination scheme and an Integrated Optics (IO) scheme with ABCD
modulation both in terms of expected sensitivity and the practical
implementation of each system.
