The new deployable tertiary mirror for the Keck I telescope (K1DM3) at the W. M. Keck Observatory has been assembled, tested and shipped to the telescope site, and is currently being installed. The mirror is capable of reflecting the beam to one of six positions around the telescope elevation ring or to retract out of the way to allow the use of Cassegrain instruments. This new functionality is intended to allow rapid instrument changes for transient event observations and improve telescope operations. This paper presents the final as-built design. Additionally, this paper presents detailed information about our alignment approach in the attempt to duplicate the instrument pointing orientation of the existing M3.
KEYWORDS: Mirrors, Telescopes, Astronomy, Calibration, Sensors, Distortion, Data modeling, Spectroscopy, James Webb Space Telescope, Magnetic resonance imaging
Motivated by the ever increasing pursuit of science with the transient sky (dubbed Time Domain Astronomy or TDA), we are fabricating and will commission a new deployable tertiary mirror for the Keck I telescope (K1DM3) at the W.M. Keck Observatory. This paper presents the detailed design of K1DM3 with emphasis on the opto- mechanics. This project has presented several design challenges. Foremost are the competing requirements to avoid vignetting the light path when retracted against a sufficiently rigid system for high-precision and repeatable pointing. The design utilizes an actuated swing arm to retract the mirror or deploy it into a kinematic coupling. The K1DM3 project has also required the design and development of custom connections to provide power, communications, and compressed air to the system. This NSF-MRI funded project is planned to be commissioned in Spring 2017.
The Lick Observatory's Shane 3-meter telescope has been upgraded with a new infrared instrument (ShARCS - Shane Adaptive optics infraRed Camera and Spectrograph) and dual-deformable mirror adaptive optics (AO) system (ShaneAO). We present first-light measurements of imaging sensitivity in the Ks band. We compare mea- sured results to predicted signal-to-noise ratio and magnitude limits from modeling the emissivity and throughput of ShaneAO and ShARCS. The model was validated by comparing its results to the Keck telescope adaptive optics system model and then by estimating the sky background and limiting magnitudes for IRCAL, the pre- vious infra-red detector on the Shane telescope, and comparing to measured, published results. We predict that the ShaneAO system will measure lower sky backgrounds and achieve 20% higher throughput across the JHK bands despite having more optical surfaces than the current system. It will enable imaging of fainter objects (by 1-2 magnitudes) and will be faster to reach a fiducial signal-to-noise ratio by a factor of 10-13. We highlight the improvements in performance over the previous AO system and its camera, IRCAL.
The University of California Observatories will design and construct a deployable tertiary mirror (named K1DM3) for the Keck 1 telescope, which will complement technical and scientific advances in the area of time-domain astronomy. The K1DM3 device will enable astronomers to swap between any of the foci on Keck 1 in under 2 minutes, both to monitor varying sources (e.g. stars orbiting the Galactic center) and catch rapidly fading sources (e.g. supernovae, flares, gamma-ray bursts). In this paper, we report on the design development during our in-progress Preliminary Design phase. The design consists of a passive wiffle tree axial support system and a diaphragm lateral support system with a 5 arcminute field-of-view mirror. The mirror assembly is inserted into the light path with an actuation system and it relies on a kinematic mechanism for achieving repeatable, precise positioning. This project, funded by an NSF MRI grant, aspires to complete by the end of 2016.
Just as the 2.4 meter Automated Planet Finder (APF) commenced its final shakedown, three significant events occurred: uncontrolled telescope oscillations while tracking, liquidation of the telescope vendor’s primary facility, and the expiration of the vendor warranty. Left with scant documentation, few external resources to draw upon, and limited direct local expertise, University of California Observatories (UCO) embarked on an initiative to stabilize the telescope control system at a minimal internal cost. This paper covers the problems encountered, our solutions, and the compromises made when the budget could not support a complete remedy. Specific topics include: measurement and alignment of linear encoder signals, and custom electronics developed to enable precise alignment of the read heads and adjustment of the interpolation electronics; the use of sensitive accelerometers to isolate and diagnose sources of vibration, and to provide immediate feedback on the stability of the servo tuning; procedures used to adjust the servo control loop, and the observable effects of parameter adjustments; assessment and validation of the performance on-sky.
A new high-order adaptive optics system is now being commissioned at the Lick Observatory Shane 3-meter telescope in California. This system uses a high return efficiency sodium beacon and a combination of low and high-order deformable mirrors to achieve diffraction-limited imaging over a wide spectrum of infrared science wavelengths covering 0.8 to 2.2 microns. We present the design performance goals and the first on-sky test results. We discuss several innovations that make this system a pathfinder for next generation AO systems. These include a unique woofer-tweeter control that provides full dynamic range correction from tip/tilt to 16 cycles, variable pupil sampling wavefront sensor, new enhanced silver coatings developed at UC Observatories that improve science and LGS throughput, and tight mechanical rigidity that enables a multi-hour diffraction-limited exposure in LGS mode for faint object spectroscopy science.
We describe the design and first-light early science performance of the Shane Adaptive optics infraRed Camera- Spectrograph (ShARCS) on Lick Observatory’s 3-m Shane telescope. Designed to work with the new ShaneAO adaptive optics system, ShARCS is capable of high-efficiency, diffraction-limited imaging and low-dispersion grism spectroscopy in J, H, and K-bands. ShARCS uses a HAWAII-2RG infrared detector, giving high quantum efficiency (<80%) and Nyquist sampling the diffraction limit in all three wavelength bands. The ShARCS instrument is also equipped for linear polarimetry and is sensitive down to 650 nm to support future visible-light adaptive optics capability. We report on the early science data taken during commissioning.
The Lick Observatory 3-meter telescope has a history of serving as a testbed for innovative adaptive optics techniques.
In 1996, it became one of the first astronomical observatories to employ laser guide star (LGS) adaptive optics as a
facility instrument available to the astronomy community. Work on a second-generation LGS adaptive optics system,
ShaneAO, is well underway, with plans to deploy on telescope in 2013. In this paper we discuss key design features and
implementation plans for the ShaneAO adaptive optics system. Once again, the Shane 3-m will host a number of new
techniques and technologies vital to the development of future adaptive optics systems on larger telescopes. Included is a
woofer-tweeter based wavefront correction system incorporating a voice-coil actuated, low spatial and temporal
bandwidth, high stroke deformable mirror in conjunction with a high order, high bandwidth MEMs deformable mirror.
The existing dye laser, in operation since 1996, will be replaced with a fiber laser recently developed at Lawrence
Livermore National Laboratories. The system will also incorporate a high-sensitivity, high bandwidth wavefront sensor
camera. Enhanced IR performance will be achieved by replacing the existing PICNIC infrared array with an Hawaii
2RG. The updated ShaneAO system will provide opportunities to test predictive control algorithms for adaptive optics.
Capabilities for astronomical spectroscopy, polarimetry, and visible-light adaptive optical astronomy will be supported.
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.
KEYWORDS: Calibration, Digital signal processing, Analog electronics, MODIS, Sensors, Modulation transfer functions, Black bodies, Head, Video, Spectrometers
NASA has built two airborne multi-spectral sensors to simulate space-borne instruments recently launched on the EOS (Earth Observing System) Terra satellite. The MODIS Airborne Simulator (MAS) and the MODIS/ASTER Simulator (MASTER) were designed to provide initial data sets to EOS investigators for algorithm development. MAS and MASTER are currently conducting calibration and validation under-flights for the MODIS and ASTER orbital instruments. These imaging spectrometers produce 50 spectral channels of 16-bit co-registered imagery data, from the blue wavelengths out though the thermal IR bands. Both systems share a common digitizer design developed originally for MAS. Greater accuracy and flexibility is achieved with high precision digital signal processors (DSPs) and field programmable gate arrays controlling the zero restoration, gain and antialiasing oversampling. Digitization rates of up to 100K samples per second per channel allow five-times oversampling at 6.25 scans per second and single sampling at 25 scans per second, resulting in aggregate data rates up to 2 Megabytes per second to disk. Both systems were designed for possible unattended operation on a NASA-ER2, but also support a realtime operator display for interactive mission evaluation on DOE’s B200 and NASA’s DC8. System design, characterization and performance will be covered by this paper.
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.