Abstract

Modern astronomical spectrometers are approaching the exquisite sensitivity to detect the signature of an Earth-mass planet around a Sun-like star, and can already do so for such planets around M dwarfs. In this talk I shall discuss the challenges involved in making these difficult measurements with the Doppler radial velocity technique, and the evolution of the design of these instruments as they seek ever-tighter control of environmental parameters, higher resolution and efficiency, and to observe large spectral regions in the optical and infra-red. A suite of new technologies like frequency stabilized laser combs, low drift etalons, and deeper understanding of the detectors is enabling a new level of precision in radial velocity measurements - as well as illustrating new challenges.  I will use the Habitable Zone Planet Finder (HPF) instrument on the HET to illustrate some of these challenges, as well as discuss emerging scientific results from HPF that will illustrate some of the challenges of stellar activity. I shall then discuss how lessons learnt from HPF have influenced the design of the NEID spectrometer, now being commissioned at the WIYN 3.5m at Kitt Peak. Time permitting I will also describe how beam-shaping diffusers are now enabling space-quality photometry from the ground to aid in photometric follow-up and confirmation of transiting exoplanets.