The array optics will produce 7 hexagonally arranged beams on the
sky. The spacing between adjacent beams is 2.0 times the diffraction
limited beam size, 22". The size and placement of the
beams is overlaid on HST images of M16 and the Hubble Deep Field
below. All 7 beams clear the elevation flange
and warm optics at the 
4 
level. Once
through the vacuum window, the beams pass through two Martin-Puplett
Interferometers (MPIs); one serves as a single-sideband (SSB) filter
and the other an LO diplexer. A lenslet array is used between the
two MPIs to refocus the beams. The required pathlength through the
MPIs and the nominal distance of the focus from the elevation flange
determines the minimum separation of the beams on the sky. In order
to minimize power loss through the MPIs and problems with size, weight,
and optical alignment, each beam has a direct line of sight from the
mixer to the secondary. The two MPI's and associated optics are cooled
to 
.
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