The Keck Planet Finder (KPF) is a fiber-fed, high-resolution, echelle spectrometer that specializes in the discovery and characterization of exoplanets using Doppler spectroscopy. In designing KPF, the guiding principles were high throughput to promote survey speed and access to faint targets, and high stability to keep uncalibrated systematic Doppler measurement errors below 30 cm s−1. KPF achieves optical illumination stability with a tip-tilt injection system, octagonal cross-section optical fibers, a double scrambler, and active fiber agitation. The optical bench and optics with integral mounts are made of Zerodur to provide thermo-mechanical stability. The spectrometer includes a slicer to reformat the optical input, green and red channels (445–600 nm and 600–870 nm), and achieves a resolving power of ∼97,000. Additional subsystems include a separate, medium-resolution UV spectrometer (383–402 nm) to record the Ca II H & K lines, an exposure meter for real-time flux monitoring, a solar feed for sunlight injection, and a calibration system with a laser frequency comb and etalon for wavelength calibration. KPF was installed and commissioned at the W. M. Keck Observatory in late 2022 and early 2023 and is now in regular use for scientific observations. This paper presents an overview of the as-built KPF instrument and its subsystems, design considerations, and initial on-sky performance.
We present a compact, double-pass cross-dispersed echelle spectrograph that is tailored specifically to cover the 383 nm to 403 nm spectral range and record R∼16,000 spectra of the stellar chromospheric Ca II H and K lines. This ‘H and K’ spectrometer was developed as a subsystem of the Keck Planet Finder (KPF), which is an extremely precise optical (440 - 870 nm) radial velocity spectrograph for Keck I, scheduled for commissioning Fall 2022, with the science objective of measuring precise masses of exoplanets. The H and K spectrometer will observe simultaneously with KPF to independently track the chromospheric activity of the host stars that KPF observes, which is expected to dominate the KPF measurement floor over long timescales. The H and K Spectrometer is fiber fed from the KPF fiber injection unit with total throughput of 4-7% (top of telescope to CCD) over its operating spectral range. Here we detail the optical design trade offs, mechanical design, and first results from alignment and integration testing.
The Keck Planet Finder (KPF) is a fiber-fed, high-resolution, high-stability spectrometer in development at the UC Berkeley Space Sciences Laboratory for the W.M. Keck Observatory. KPF is designed to characterize exoplanets via Doppler spectroscopy with a goal of a single measurement precision of 0.3 m s-1 or better, however its resolution and stability will enable a wide variety of astrophysical pursuits. Here we provide post-preliminary design review design updates for several subsystems, including: the main spectrometer, the fabrication of the Zerodur optical bench; the data reduction pipeline; fiber agitator; fiber cable design; fiber scrambler; VPH testing results and the exposure meter.
Remote sensing of Earth at ultraviolet wavelengths offers the capability to retrieve key environmental parameters that provide remarkable insight into space weather conditions. The miniaturized UV imager (MUVI) instrument is a currently funded NASA technology development effort that expands on capability developed from recent flight experience to build and qualify a small, relatively simple UV imager that can be tuned for a range of purposes. The goal is to revisit earlier designs of suppressive imagers, obviating the need for gratings, slits, and long optical paths, redeveloping a direct imaging capability in a CubeSat type form-factor. Combining high heritage components with improved imaging technologies, MUVI provides science performance comparable to high-performance imagers developed and flown for prior research missions at much lower mass and cost points. A compelling scientific design for future missions will be to make space-based observations from multiple vantage points from one or more orbit planes. Multiple-observatory mission designs, including those implemented using the CubeSat form-factor, are more accessible now due to a great deal of research and commercial work toward miniaturization of spacecraft subsystems. It is likely that small scientific payloads will greatly benefit upcoming Heliophysics missions if appropriate technologies are developed. An overview of the MUVI instrument is described here, along with development status after year 1 of funding.
A vacuum-compatible manipulator was developed to calibrate the Miniaturized UltraViolet Imaging instrument (MUVI). The pointing resolution of the manipulator was evaluated, along with its ability to neutralize known optical misalignments. Field of View sweep tests were performed to quantify manipulator parameters using optical ground support equipment. Systematic errors were effectively reduced by a factor of 49 and 7 in the horizontal and vertical translation axes, respectively. Furthermore, the pointing resolution was measured to be less than 1 arcmin, which satisfied the instrument’s science calibration requirement.
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