B. Kruschwitz, J. Kwiatkowski, C. Dorrer, M. Barczys, A. Consentino, D. Froula, M. Guardalben, E. Hill, D. Nelson, M. Shoup, D. Turnbull, L. Waxer, D. Weiner
The OMEGA EP laser has been upgraded to provide a UV wavelength-tunable beam to support the study of wavelength detuning for the mitigation of cross-beam energy transfer in direct-drive inertial confinement fusion. The beamline delivers up to 0.5 TW in pulses up to 1-ns duration (0.1 TW up to 2.5 ns), to either the OMEGA or OMEGA EP target chambers with wavelength tunable from 350.2 to 353.4 nm. The upgrade leverages the existing optical parametric amplification (OPA) system in the short-pulse front end of OMEGA EP Beamline 1 for amplification of a new tunable, narrowband fiber front end over a broad spectral range. The tunable OPA output is spatially shaped to form a round OMEGA-like beam, which is amplified in the OMEGA EP beamline, then frequency tripled and characterized using the existing OMEGA EP long-pulse infrastructure. A new 3ω beam-transport system intercepts the tunable UV beam near the OMEGA EP target chamber and image relays it to the P9 port of the OMEGA target chamber for joint shots with the OMEGA 60-beam laser. Commissioning of the tunable UV capability has been completed, and four experimental campaigns have been supported with the tunable beam
A beam-shaping system, based on a liquid-crystal-on-silicon spatial light modulator, has been deployed on two of the long-pulse UV beamlines of the OMEGA EP laser. Simultaneous control of both amplitude and phase with a single spatial light modulator is possible by encoding intensity information on a high-frequency carrier phase, which is subsequently removed by a low-pass spatial filter. The beam-shaping system has been integrated into operations of the existing front-end laser source and has demonstrated improved beam uniformity at multiple points in the laser. The system operates in closed loop to optimize the input infrared beam’s spatial-amplitude profile prior to amplification and frequency conversion. Measured amplified beam profiles from near-field cameras along the laser beam’s path are used to specify the desired input infrared beam shape. The system is used to correct local hot spots in the input beam profile and to refine the amplifier gain precompensation profile that is applied to the input beam with separate static apodizers. At present, the beam-shaping system is used only to correct amplitude variations in the beam profile, but future use may also utilize the system’s capability to apply wavefront corrections to the beam.
OSIRIS is an integral field infrared spectrograph designed for the Keck Adaptive Optics System. It utilizes an array of lenses and the latest infrared detector to simultaneously obtain more than 3000 spectra over a rectangular field of view (up to 48x64 spatial elements). In its broad band mode (16x64 spectra), each spectrum contains more than 1700 wavelength channels and covers an entire infrared band at a resolution of 3800. Due to the extremely low backgrounds between night sky lines and at AO spatial samplings, the instrument is also extremely sensitive. Here we present first results obtained during commissioning of the instrument following First Light in February 22, 2005. We demonstrate the performance of the instrument, in particular together with the Keck Observatory's adaptive optics system and provide a flavor of the science addressed with OSIRIS.
We present an overview of the OSIRIS integral field spectrograph which was recently commissioned on the Keck II Telescope. OSIRIS works with the Keck Adaptive Optics system and utilizes an infrared transmissive lenslet array to sample a rectangular field of view at close to the Keck diffraction limit. By packing the spectra close together (2 pixel rows per spectrum) and using the Rockwell Hawaii-2 detector (wavelengths between 1 and 2.5 microns), we achieve a relatively large field of view (up to 6."4) while maintaining full broad-band spectral coverage at a resolution of 3800. Among the challenges of the instrument are: a fully cryogenic design (approximately 250 kg are brought down to 55K); four spatial scales from 0."02 to 0."10; extremely low wavefront error (approximately 25 nm of non-common path error); large all aluminum optics for the spectrograph; extremely repeatable spectral formats; and a sophisticated data reduction pipeline. OSIRIS also serves as a starting point for our design of IRIS which is a planned integral field spectrograph for the Thirty Meter Telescope.
OSIRIS is a near infrared diffraction limited imaging field spectrograph under development for the Keck observatory adaptive optics system and scheduled for commissioning in fall 2004. Based upon lenslet pupil imaging, diffraction grating, and a 2Kx2K Hawaii2 HgCdTe array, OSIRIS is a highly efficient instrument at the forefront of today's technology. OSIRIS will deliver per readout up to 4096 diffraction limited spectra in a complex interleaved format, requiring new challenges to be met regarding user interaction and data reduction. A data reduction software package is under development, aiming to provide the observer with a facility instrument allowing him to concentrate on science rather than dealing with instrumental as well as telescope and atmosphere related effects. Together with OSIRIS, a pipeline for basic data reduction will be provided for a new Keck instrument for the first time. A status report is presented here together with some aspects of the data reduction pipeline.
OSIRIS is an infrared integral-field spectrograph built for the Keck AO system. Integral-field spectrographs produce very complicated raw data products, and OSIRIS is no exception. OSIRIS produces frames that contain up to 4096 interleaved spectra. In addition to the IFU capabilities of OSIRIS, the instrument is equipped with a parallel-field imager to monitor current AO conditions by imaging an off-axis star and evaluating its PSF. The design of the OSIRIS software was driven by the complexity of the instrument, switching the focus from simply controlling the instrument components to targeting the acquisition of usable scientific data.
OSIRIS software integrates the planning, execution, and reduction of observations. An innovation in the OSIRIS control software is the formulation of observations into 'datasets' rather than individual frames. Datasets are functional groups of frames organized by the needs and capabilities of the data reduction software (DRS). A typical OSIRIS dataset consists of dithered spectral observations, coupled with the associated imaging data from the parallel-field AO PSF imager. A Java-based planning tool enables 'sequences' of datasets to be planned and saved both prior to and during observing sessions. An execution client interprets these XML-based files, configures the hardware servers for both OSIRIS and AO, and executes the observations. The DRS, working on one dataset of raw data at a time, produces science-quality data that is ready for analysis. This methodology should lead to superior observational efficiency, decreased likelihood of observer error, minimized reduction time, and therefore, faster scientific discovery.
We present the design for a recently approved instrument for the Keck Telescope. Called OSIRIS, it was inspired by the optical spectrograph TIGER of R. Bacon et al. and will utilize an infrared transmissive lenslet array to sample a rectangular field of view at close to the Keck diffraction limit. By packing the spectra very closely together (2 pixel rows per spectrum) and using the Rockwell Hawaii-2 detector (wavelengths between 1 and 2.5 microns), we will achieve a relatively large field of view (up to 6."4) while maintaining full broad-band spectral coverage at a resolution of 3900. Due to the extremely low backgrounds between night sky lines and at AO spatial samplings, the instrument will reach point source sensitivities several times fainter than any existing infrared spectrograph. We are also coupling a separate infrared AO camera dubbed SHARC to work as an acquisition camera and to monitor the point spread function's behavior during long spectroscopic exposures. Among the challenges of the instrument are: a fully cryogenic design, four spatial resolutions from 0."02 to 0."10, large aluminum optics for the spectrography, extremely repeatable spectral formats and a sophisticated data reduction pipeline.
OSIRIS (OH-Suppressing InfraRed Integral-field Spectrograph) is a new facility instrument for the Keck Observatory. Starting in 2004, it will provide the capability of performing three-dimensional spectroscopy in the near-infrared z, J, H, and K bands at the resolution limit of the Keck II telescope, which is equipped with adaptive optics and a laser guide star. The innovative capabilities of OSIRIS will enable many new observing projects. Galaxies in the
early Universe will be among the most interesting targets for OSIRIS, which will perform detailed studies of their stellar content and dynamical properties. In more exotic objects, such as quasars, radio galaxies, and more nearby active galactic nuclei, OSIRIS can elucidate the relation of the central black hole to the properties of the host galaxy, and the mechanism by which gas
is fed into the central engine. In the center of our own Galaxy, it will be possible to search for signatures of interaction between the massive black hole and stars in its immediate vicinity. Closer to home, OSIRIS will perform spectroscopic observations of young stars and their environment, and of brown dwarfs. Imaging spectroscopy of the giant planets, their moons, and asteroids will shed new light on meteorology, mineralogy, and volcanism in the Solar System. OSIRIS observations of Kuiper Belt objects will provide sufficient sensitivity to establish their surface composition, which will contribute substantially to our understanding of the history of the Solar System.
OSIRIS is a near infrared diffraction limited imaging field spectrometer under development for the Keck observatory adaptive optics system. Based upon lenslet pupil imaging, diffraction grating, and a 2K×2K Hawaii2 HgCdTe array, OSIRIS is a highly efficient instrument at the forefront of today’s technology. OSIRIS will deliver per readout up to 4096 diffraction limited spectra in a complex interleaved format, requiring new challenges to be met regarding user interaction and data reduction. A data reduction software package is under development, aiming to provide the observer with a facility instrument allowing him to concentrate on science rather than dealing with instrumental as well as telescope and atmosphere related effects. Together with OSIRIS, a pipeline for basic data reduction will be provided for a new Keck instrument for the first time. Some aspects of the data reduction pipeline will be presented here. The OSIRIS instrument as such, the astronomical background as well as other software tools were presented elsewhere on this conference.
OSIRIS is an infrared integral-field spectrograph being built for the Keck AO system. OSIRIS presents novel data reduction and user-interaction challenges which are addressed by software being developed for OSIRIS. The complex raw data frames, containing up to 4096 interleaved spectra, are reduced in real-time and meaningfully displayed for quality-of-observation feedback to observers. Following an observing night, data are optimally reduced to science-quality data cubes in a semi-automated fashion. Further, the software must efficiently coordinate OSIRIS' spectroscopic observations with the SHARC off-axis imager and the AO system.
To meet these demands, OSIRIS software is comprehensive and integrates the planning, execution, and reduction of observations. Facilitating this architecture is the formulation of observations into 'datasets', rather than into individual frames. Datasets are functional groups of frames organized by the needs and capabilities of the data reduction software (DRS). A typical dataset consists of dithered OSIRIS observations, coupled with associated off-axis AO PSF imagery from SHARC. A Java-based planning tool enables 'sequences' of datasets to be planned and saved both prior to and during observing sessions. An execution client interprets these XML-based files, and configures the hardware servers for OSIRIS, SHARC, and AO before executing the observations. As observations are completed, extensive information
about the instrument and observatory are collated in an archival relational database. The DRS then uses information in the database, as well as archived calibration data and SHARC PSF data to produce a final science-quality data product, which may include differential refraction corrections, 3D PSF modeling/deconvolution, and OH-suppression.
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