We report on the preliminary design of W.M. Keck Observatory's (WMKO's) next-generation adaptive optics (NGAO)
facility. This facility is designed to address key science questions including understanding the formation and evolution
of today's galaxies, measuring dark matter in our galaxy and beyond, testing the theory of general relativity in the
Galactic Center, understanding the formation of planetary systems around nearby stars, and exploring the origins of our
own solar system. The requirements derived from these science questions have resulted in NGAO being designed to
have near diffraction-limited performance in the near-IR (K-Strehl ~ 80%) over narrow fields (< 30" diameter) with
modest correction down to ~ 700 nm, high sky coverage, improved sensitivity and contrast and improved photometric
and astrometric accuracy. The resultant key design features include multi-laser tomography to measure the wavefront
and correct for the cone effect, open loop AO-corrected near-IR
tip-tilt sensors with MEMS deformable mirrors (DMs)
for high sky coverage, a high order MEMS DM for the correction of atmospheric and telescope static errors to support
high Strehls and high contrast companion sensitivity, point spread function (PSF) calibration to benefit quantitative
astronomy, a cooled science path to reduce thermal background, and a high-efficiency science instrument providing
imaging and integral field spectroscopy.
The Ken and Gloria Levy Spectrometer is being constructed at the Instrument Development Laboratory (Technical
Facilities) of UCO/ Lick Observatory for use on the 2.4 meter Automated Planet Finder Telescope at Mt. Hamilton. The
mechanical design of the instrument has been optimized for precision Doppler measurements. A key component of the
design is the space-frame structure that contains passive thermal compensation. Determinate hexapod structures are used
to mount the collimator, prism, and echelle grating. In this paper we describe the instrument mechanical design and some
features that will help it detect rocky planets in the habitable zone.
A mosaic of two 2k x 4k fully depleted, high resistivity CCD
detectors was installed in the red channel of the Low Resolution
Imaging Spectrograph for the Keck-I Telescope in June, 2009 replacing
a monolithic Tektronix/SITe 2k x 2k CCD. These CCDs were fabricated
at Lawrence Berkeley National Laboratory (LBNL) and packaged and
characterized by UCO/Lick Observatory. Major goals of the detector
upgrade were increased throughput and reduced interference fringing
at wavelengths beyond 800 nm, as well as improvements in the
maintainability and serviceability of the instrument. We report on
the main features of the design, the results of optimizing detector
performance during integration and testing, as well as the
throughput, sensitivity and performance of the instrument as
characterized during commissioning.
W. M. Keck Observatory (WMKO) is currently engaged in the design of a powerful new Adaptive Optics (AO) science
capability providing precision correction in the near-IR, good correction in the visible, and faint object multiplexed
integral field spectroscopy. Improved sensitivity will result from significantly higher Strehl ratios over narrow fields (<
30" diameter) and from lower backgrounds. Quantitative astronomy will benefit from improved PSF stability and
knowledge. Strehl ratios of 15 to 25% are expected at wavelengths as short as 750 nm. A multi-object AO approach
will be taken for the correction of multiple science targets over modest fields of regard (< 2' diameter) and to achieve
high sky coverage using AO compensated near-IR tip/tilt sensing. In this paper we present the conceptual design for this
system including discussion of the requirements, system architecture, key design features, performance predictions and
implementation plans.
Visible Light Laser Guidestar Experiments (ViLLaGEs) is a new Micro-Electro Mechanical Systems (MEMS)
based visible-wavelength adaptive optics (AO) testbed on the Nickel 1-meter telescope at Lick Observatory. Closed
loop Natural Guide Star (NGS) experiments were successfully carried out during engineering during the fall of
2007. This is a major evolutionary step, signaling the movement of AO technologies into visible light with a MEMS
mirror. With on-sky Strehls in I-band of greater than 20% during second light tests, the science possibilities have
become evident.
Described here is the advanced engineering used in the design and construction of the ViLLaGEs system, comparing
it to the LickAO infrared system, and a discussion of Nickel dome infrastructural improvements necessary for this
system. A significant portion of the engineering discussion revolves around the sizable effort that went towards
eliminating flexure. Then, we detail upgrades to ViLLaGEs to make it a facility class instrument. These upgrades
will focus on Nyquist sampling the diffraction limited point spread function during open loop operations,
motorization and automation for technician level alignments, adding dithering capabilities and changes for near
infrared science.
The Next Generation Adaptive Optics (NGAO) system will represent a considerable advancement for high resolution
astronomical imaging and spectroscopy at the W. M. Keck Observatory. The AO system will incorporate multiple laser
guidestar tomography to increase the corrected field of view and remove the cone effect inherent to single laser guide
star systems. The improvement will permit higher Strehl correction in the near-infrared and diffraction-limited correction
down to R band. A high actuator count micro-electromechanical system (MEMS) deformable mirror will provide the
on-axis wavefront correction to a number of instrument stations and additional MEMS devices will feed multiple
channels of a deployable integral-field spectrograph. In this paper we present the status of the AO system design and
describe its various operating modes.
The Lick Observatory is pursuing new technologies for adaptive optics that will enable feasible low cost laser guidestar
systems for visible wavelength astronomy. The Villages system, commissioned at the 40 inch Nickel Telescope this past
Fall, serves as an on-sky testbed for new deformable mirror technology (high-actuator count MEMS devices), open-loop
wavefront sensing and control, pyramid wavefront sensing, and laser uplink correction. We describe the goals of our
experiments and present the early on-sky results of AO closed-loop and open-loop operation. We will also report on our
plans for on-sky tests of the direct-phase measuring pyramid-lenslet wavefront sensor and plans for installing a laser
guidestar system.
The MEMS-AO/Villages project consists of a series of on-sky experiments that will demonstrate key new
technologies for the next generation of adaptive optics systems for large telescopes. One of our first goals is to
demonstrate the use of a micro-electro-mechanical systems (MEMS) deformable mirror as the wavefront correcting
element. The system is mounted the 1-meter Nickel Telescope at the UCO/Lick Observatory on Mount Hamilton. It
uses a 140 element (10 subapertures across) MEMS deformable mirror and is designed to produce diffraction-limited
images at wavelengths from 0.5 to 1.0 microns. The system had first light on the telescope in October 2007.
Here we report on the results of initial on-sky tests.
As adaptive optics (AO) matures, it becomes possible to envision AO systems oriented towards specific important scientific goals rather than general-purpose systems. One such goal for the next decade is the direct imaging detection of extrasolar planets. An "extreme" adaptive optics (ExAO) system optimized for extrasolar planet detection will have very high actuator counts and rapid update rates - designed for observations of bright stars - and will require exquisite internal calibration at the nanometer level. In addition to extrasolar planet detection, such a system will be capable of characterizing dust disks around young or mature stars, outflows from evolved stars, and high Strehl ratio imaging even at visible wavelengths. The NSF Center for Adaptive Optics has carried out a detailed conceptual design study for such an instrument, dubbed the eXtreme Adaptive Optics Planet Imager or XAOPI. XAOPI is a 4096-actuator AO system, notionally for the Keck telescope, capable of achieving contrast ratios >107 at angular separations of 0.2-1". ExAO system performance analysis is quite different than conventional AO systems - the spatial and temporal frequency content of wavefront error sources is as critical as their magnitude. We present here an overview of the XAOPI project, and an error budget highlighting the key areas determining achievable contrast. The most challenging requirement is for residual static errors to be less than 2 nm over the controlled range of spatial frequencies. If this can be achieved, direct imaging of extrasolar planets will be feasible within this decade.
The Lawrence Berkeley National Laboratory has been developing fully-depleted high resistivity CCDs. These CCDs exhibit very high red quantum efficiency, no red fringing, and very low lateral charge diffusion, making them good candidates for astronomical applications that require better red response or better point spread function than can typically be achieved with standard thinned CCDs. For the LBNL 2Kx4K CCD we have developed a four-side mosaic package fabricated from aluminum nitride. Our objectives have been to achieve a flatness of less than 10 micrometers peak-to-valley and a consistent final package thickness variation of 10 micrometers or less in a light-weight package. We have achieved the flatness objective, and we are working toward the thickness variation objective.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.