3D: The next generation near-infrared 
imaging spectrometer

Weitzel, L.; Krabbe, A.; Kroker, H.; Thatte, Niranjan; Tacconi-Garman, L. E.; Cameron, M.; Genzel, R.

doi:10.1051/aas:1996266

Cited by 141 publications

(104 citation statements)

References 31 publications

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“…Using T Tau N (m V ¼ 9:6) as a natural guide star, ALFA delivered angular resolutions (FWHM) of 0>14 in H band and 0>16 in K band throughout the observations. The integral field spectrometer 3D yields spectra of an entire 16 Â 16 pixel field at resolutions of R % 1000 2100 ( /D ) (Weitzel et al 1996;Anders et al 1998). The image scale of 0>07 pixel À1 results in a field of view (FOV) of 1 00 .…”

Section: Observationsmentioning

confidence: 99%

Spatially Resolved Imaging Spectroscopy of T Tauri

Kasper

Feldt

Herbst

et al. 2002

ApJ

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The small separation of the individual stellar components in the T Tau system has prevented spectroscopy of the individual components in the near-infrared (NIR) in the past. We present NIR data (H and K band) on this object taken using the Adaptive Optics with a Laser for Astronomy (ALFA) system in combination with the 3D integral field spectrograph. Except for the Brackett series seen in emission, the NIR spectra of T Tau S appear featureless, suggesting that warm dust dominates the radiation. No rovibrational lines of molecular hydrogen were found in close vicinity to the stars. The Brackett line emission from T Tau N and S could not be resolved with the 3.5 m telescope, implying that it arises within 6 AU from the stars. The line ratios between Br (2.166 lm) and Br10 (1.736 lm) toward T Tau N and T Tau S are similar, suggesting similar selective extinctions toward the respective emitting regions. Our results are consistent with a model that describes T Tau S as a pre-main-sequence star surrounded by a small edge-on disk, leaving the polar regions relatively unobscured. We present numerical simulations which support this model.

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Section: Observationsmentioning

confidence: 99%

Spatially Resolved Imaging Spectroscopy of T Tauri

Kasper

Feldt

Herbst

et al. 2002

ApJ

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“…However, in applications that do not require imaging systems with maximized spatial resolution or that can employ imaging systems having spatial resolution below a predefined threshold, axially-asymmetric positioning of the secondary objectives forming multiple images in the imaging plane can be sufficient. Using secondary objectives of the reimaging subsystem at the exit pupil to spatially segment the incoming beam allows us to avoid the use of auxiliary beam-splitting components used in previous imaging techniques [14] . This increases the system tolerance to mechanical misalignments.…”

Section: Figure 15mentioning

confidence: 99%

“…Bulk-optic [14] and fiber-optic [15] high spectral resolution snapshot imaging systems require rearranging a two-dimensional image into a one-dimensional array before being converted to a spectral data cube by the computed tomographic imaging spectrometer. The one-dimensional image input is spectrally dispersed at the detector by the diffractive optical element.…”

Section: Introductionmentioning

confidence: 99%

Novel, Noninvasive Multispectral Snapshot Imaging System to Measure and Map the Distribution of Human Retinal Vessel and Tissue Hemoglobin Oxygen Saturation

Firn

Khoobehi

2015

International Journal of Ophthalmic Research

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capillary mimicking a vessel. The quantitative calculations from the healthy subject, as well as the qualitative oxygen saturation maps, show oxygen saturation levels consistent with those in the literature. CONCLUSION: This system is clinically valuable for diagnosing and monitoring diseases affecting ocular oxygen saturation, such as glaucoma, diabetic retinopathy, age-related macular degeneration, and others. Our reliable method is capable of documenting tissue oxygenation throughout disease progression. © 2015 ACT. All rights reserved. INTRODUCTIONPathologic conditions in the retina and optic nerve head (ONH) can cause vision loss and blindness. Both structures have a high demand for oxygen, and loss of the normal oxygen supply through vascular insufficiency is believed to play an important role in diseases affecting the retina and ONH. Hypoxia of the retina and ONH is believed to be a factor in the development of ocular vascular disorders, such as diabetic retinopathy (DR), arteriovenous occlusion, and glaucoma. The ability to obtain relative measurements of oxygen saturation in the human ocular fundus could aid in the diagnosis and monitoring of these and other disorders. For example, measurement of changes in retinal and ONH oxygen saturation under controlled conditions could establish relationships among oxygen consumption, ABSTRACT AIM: To design and implement a snapshot imaging system capable of mapping oxygen saturation of retinal vessels and tissue clinically for the first time. MATERIALS AND METHODS: Our image-splitting design is attached to the imaging portions of a fundus camera. A relay subsystem and reimaging system convert reflected white light from the eye into seven monochromatic images simultaneously. Our algorithm uses intensity information at each of these discrete wavelengths to approximate the area between the oxy-and deoxyhemoglobin spectral curves, which has been shown to be proportional to oxygen saturation. We used MATLAB to convert this information into colorcoded oxygen saturation maps of the optic nerve head. We validated our system by using it on a model eye with a capillary of known blood oxygen saturation, then used it In vivo to obtain quantitative values of human oxygen saturation for veins and tissue. RESULTS: By collecting seven images simultaneously with one snapshot, our system is the first to document and reproducibly map oxygen saturation of the retinal vessels and tissue. Oxygen saturation values are color-coded, with oxygen-rich arteries in red, oxygen-poor veins in blue, and intermediate tissue yellow-green. Our system's calculations agree with co-oximeter readings of blood in a model eye

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“…During August 1998, the MPE 3D imaging spectrometer (Weitzel et al 1996), which obtains simultaneously Hor K-band spectra of an entire 16×16 pixel field, was used with ALFA. In order to facilitate this, an aperture interchange module (AIM, Anders et al 1998) has been built as an interface to allow the pixel scale to be changed between 0.25 and 0.07 per pixel, as well as providing the ability for efficient sky observations with minimal overhead.…”

Section: Integral Field Spectroscopy: Heimentioning

confidence: 99%

The science potential of ALFA: Adaptive optics with natural and laser guide stars

Davies

Ott

Eckart

et al. 1999

Astron. Astrophys. Suppl. Ser.

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Abstract. Adaptive optics with laser guide stars is mandatory in order to make use of the full capabilities of 8-m class telescopes. However, progress has been slow in two particular areas: techniques for spectroscopy at diffraction limited resolution and wavefront sensing on laser guide stars. ALFA -currently the only European laser guide star adaptive optics system, and the only one in the world open to guest observers -has made significant advances in both of these. In this paper we report on our first results from summer 1998, representing significant improvements over previous performance. We report on observations using natural guide stars which demonstrate that for bright stars (m V ∼ < 8) ALFA can now reach K-band Strehl ratios in excess of 60% and easily resolve binaries at the diffraction limit of the telescope. We then present some of the first integral field spectroscopy at diffraction limited scales, showing we are able to distinguish spectra of binary stars with a separation of only 0.26 . We also discuss results from a wide field image, which indicate that useful correction (allowing binary stars and circumstellar dust shells to be resolved) can be achieved from a relatively faint star to a radius of at least 1 . Our last set of results include a correction on a galaxy using the laser guide star as the reference. The best result to date is of the galaxy UGC 1347 in Abell 262. Correcting tip-tilt on a star 41 away and higher orders on the laser, we achieved an increase in peak intensity of 2.5, and a reduction in FWHM from 1.07 to 0.40 .

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3D: The next generation near-infrared imaging spectrometer

Cited by 141 publications

References 31 publications

Spatially Resolved Imaging Spectroscopy of T Tauri

Spatially Resolved Imaging Spectroscopy of T Tauri

Novel, Noninvasive Multispectral Snapshot Imaging System to Measure and Map the Distribution of Human Retinal Vessel and Tissue Hemoglobin Oxygen Saturation

The science potential of ALFA: Adaptive optics with natural and laser guide stars

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