A New Design For a Fringe-Tracking Interferometric Array

A conceptual design for a fringe-tracking interferometric array is presented. Unlike the conventional design which splits N beams of an N aperture array and combines them into N(N 1)/2 fringes, only N broad-band fringes are formed and measured in the fringe-tracking channel to determine N 1 instantaneous piston di erences. Beam splitting and combining are accomplished by optics composed of a collimator mirror/lens, N multi-faced mirrors, and a camera mirror/lens. The same optics can be used to separate the fringe-tracking and science integration channels. The simplicity of the optical train potentially achieves a high throughput of the entire system. System optimization and sensitivity estimation are attempted for a four-aperture interferometer. A limiting magnitude of K=10 will be reached at a good astronomical site with the current detector technology. Subject headings: interferometer: infrared | instrumentation: infrared