  We are developing a stable and precise spectrograph for the Large Binocular
Telescope (LBT) named "iLocater." The instrument comprises three principal
components: a cross-dispersed echelle spectrograph that operates in the
YJ-bands (0.97-1.30 microns), a fiber-injection acquisition camera system, and
a wavelength calibration unit. iLocater will deliver high spectral resolution
(R~150,000-240,000) measurements that permit novel studies of stellar and
substellar objects in the solar neighborhood including extrasolar planets.
Unlike previous planet-finding instruments, which are seeing-limited, iLocater
operates at the diffraction limit and uses single mode fibers to eliminate the
effects of modal noise entirely. By receiving starlight from two 8.4m diameter
telescopes that each use "extreme" adaptive optics (AO), iLocater shows promise
to overcome the limitations that prevent existing instruments from generating
sub-meter-per-second radial velocity (RV) precision. Although optimized for the
characterization of low-mass planets using the Doppler technique, iLocater will
also advance areas of research that involve crowded fields, line-blanketing,
and weak absorption lines.
