Coupling efficiency of starlight to low-order-mode optical fibers using adaptive optics: rationale and experiments using the Wavefront Control Experiment

Planetary detection using doppler shifts requires very high resolution spectrographs which are stable over periods of years. Single or low order mode optical fibers have advantages in this application since they produce spatially scrambled Gaussian input illumination and diffraction limited size input image for spectrograph slit. Very high resolution spectroscopy is thus possible with modest dimensions of the spectrograph. This results in greatly lowering the cost of spectrograph and increasing the stability. However, adaptive optics system is needed to improve the light coupling efficiency. This paper reviews the potential of this technique and presents some preliminary laboratory experiments with the Wavefront Control Experiment (WCE). Plans of future experiment after installing the WCE in a Coude room of a 40 degree(s) reflector telescope at Yerkes Observatory are also presented.