Keck Interferometer status and plans

Keck Interferometer is a NASA-funded project to combine the two 10 in Keck telescopes for high sensitivity near-infrared fringe visibility measurements, nulling interferometry at 10 mum to measure the quantity of exozodiacal emission around nearby stars, and differential-phase measurements to detect "hot-Jupiters" by their direct emission. It is being developed by the Jet Propulsion Laboratory, the W. M. Keck Observatory, and the Michelson Science Center. Recent activity has included formal visibility mode commissioning, as well as science observations, and we briefly review some of the significant technical aspects and updates to the system. We have also completed laboratory development of the miller. The nuller uses two modified Mach-Zehnder input millers, a Michelson cross combiner, and a 10 gm array camera to produce background-limited null measurements. To provide required temporal stability for the miller, the system incorporates end-to-end laser metrology with phase referencing from two 2.2 mum fringe trackers. The miller recently completed its pre-ship review and is being installed on the summit. After miller integration and test, the differential phase mode will be deployed, which will use a 2-5 mum fringe detector in combination with a precision path length modulator and a vacuum delay line for dispersion control.