SPIFFI image slicer: revival of image slicing with plane mirrors

Tecza, Matthias; Thatte, Niranjan; Eisenhauer, F.; Mengel, Sabine; Roehrle, Claudia; Bickert, K.

doi:10.1117/12.395451

Cited by 13 publications

(9 citation statements)

References 5 publications

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“…No glue is used in the assembly. A detailed description of the design and the manufacturing technique can be found in [11,13]. The problems in the manufacturing of the slicer are mainly in the process of cleaning and handling.…”

Section: Image Slicermentioning

confidence: 99%

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SINFONI - Integral field spectroscopy at 50 milli-arcsecond resolution with the ESO VLT

Eisenhauer¹,

Bonnet²,

Abuter³

et al. 2003

SPIE Proceedings

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345

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SINFONI is an adaptive optics assisted near-infrared integral field spectrometer for the ESO VLT. The Adaptive Optics Module (built by the ESO Adaptive Optics Group) is a 60-elements curvature-sensor based system, designed for operations with natural or sodium laser guide stars. The near-infrared integral field spectrometer SPIFFI (built by the Infrared Group of MPE) provides simultaneous spectroscopy of 32 x 32 spatial pixels, and a spectral resolving power of up to 3300. The adaptive optics module is in the phase of integration; the spectrometer is presently tested in the laboratory. We provide an overview of the project, with particular emphasis on the problems encountered in designing and building an adaptive optics assisted spectrometer. 1. SINFONI: ADAPTIVE OPTICS AND INTEGRAL FIELD SPECTROSCOPY SINFONI (SINgle Faint Object Near-IR Investigation) is an adaptive optics assisted near infrared integral field spectrometer mounted to the European Southern Observatory (ESO) VLT (Very Large Telescope). The instrument is a combination ofthe Adaptive Optics module [1], a clone ofMACAO (Multiple Application Curvature Adaptive Optics), developed and built by ESO, and of the near infrared integral field spectrograph SPIFFI (SPectrograph for Infrared Faint Field Imaging) [2], developed and built by the Max-Planck-Institute for extraterrestrial Physics (MPE).Currently, ESO offers two state-of-the-art near infrared instruments at the VLT: ISAAC [3] for seeing limited infrared imaging and spectroscopy, and NAOS/CONICA [4,5] for high order adaptive optics imaging and low-resolution spectroscopy. However, spectroscopy of faint objects with diffraction limited angular resolution at an eight-meter telescope will strongly benefit from a dedicated instrument, which combines the following characteristics: first, diffraction limited observations at near infrared wavelengths, optimized for faint wave-front reference stars and laser guide star operations; second, instantaneous spectroscopy of a two dimensional field with sufficiently high spectral resolution for deep observations between the night sky emission lines.Both partner institutes collected extensive experience with diffraction-limited spectroscopy with their instruments ADONIS/SHARP [6] at the La Silla 3.6 m telescope, and ALFA/3D [7] at the Calar Alto Observatory 3.5 m telescope. Our conclusion is that when observing with adaptive optics, integral field spectroscopy gains significantly over long-slit spectroscopy and Fabry-Perot imaging. The latter suffers significantly from the variation of the sky emission and the point-spread-function (PSF) between consecutive images, and consumes exorbitant observing time for large wavelength coverage. Long-slit spectroscopy, on the other hand, lacks the essential two-dimensional information for decomposing the spatial flux distribution, and loses most ofthe source flux for a diffraction limited slit width and moderate correction of the atmospheric aberrations. In addition, flexure within the instruments complicates the acquisition of...

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Section: Image Slicermentioning

confidence: 99%

“…The working principle of the integral field spectrometer SPIFFI is copied from its precursor 3D [10]. Both instruments are built around an image slicer with plane mirrors [11]. However, SPIFFI is fully cryogenic, including the image slicer, and the number of spatial pixels is four times as large.…”

mentioning

confidence: 99%

SINFONI - Integral field spectroscopy at 50 milli-arcsecond resolution with the ESO VLT

Eisenhauer¹,

Bonnet²,

Abuter³

et al. 2003

SPIE Proceedings

Self Cite

345

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“…Through further study on typical 3-mirror design, it's indicated that big fold angle on spherical mirror is the primary reason to degrade image quality, especially spherical pupil mirror, see Figure 4. Flat pupil mirrors used in some 2-mirror designs don't cause this serious degradation, for example, Keck II -KCWI [4] and VLT -SPIFFI [6]. And the design of Hale -SWIFT [7] and VLT -MUSE [8] also verifies that it's feasible to compensate the imaging function deletion of flat pupil mirror by locating slit mirror at a specific position.…”

Section: Optical Designmentioning

confidence: 99%

The infrared imaging spectrograph (IRIS) for TMT: design of image slicer

Zhang

Zhou

Moore

et al. 2018

Ground-Based and Airborne Instrumentation for Astronomy VII

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The InfraRed Imaging Spectrograph (IRIS) is one of three first light science instruments for the Thirty Meter Telescope (TMT). It will provide dedicated function of imaging and integral field spectroscopic observations in parallel with the assistance of a Narrow Field InfraRed Adaptive Optics System (NFIRAOS). The IRIS imager delivers celestial light to a dual-channel Integral Field Spectrograph (IFS) through a pair of pick-off mirrors in the central field. The IFS creates multi-functional ability to explore the universe in IR (0.84-2.4um) with moderate spectral resolution of R=4,000/8,000 and four spaxel scales of 4, 9, 25, 50 milli-arc-seconds (mas). An image slicer serves one of the two spectral channels as its Integral Field Unit (IFU) in two coarse spaxel scales of 25 and 50mas over the continuous science fields of 2.2x1.125 arc-seconds (arcsec) and 4.4x2.25 arcsec respectively. It splits the field to 88 unit systems, and then re-images at two parallel slits in order to take full advantage of the detector (4Kx4K @ 15um). This paper describes a novel all-reflective design of image slicer, which uses a new 'brick stage' layout to stagger the adjacent mirrors and deliver image quality close to diffraction limit. The quasi-telecentric optical design gives more friendly interfaces with pre-optics and spectrograph than the conceptual design. Here, more technical issues are discussed to guide the further study on optical performance and fabrication feasibility.

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“…We could reproduce this behaviour by varying the pupil position on the grating. One possible source of movement of the pupil position is the image slicer, which is described in detail in Tecza et al (2000). 18 A torsional deformation of a slicer mirror with a measured amplitude of 2 HeNe fringes (close to what could be expected based on measurements of the slicer mirrors; see Eisenhauer et al (2003) 1 for an example of a slicer interferogram) would result in the pupil shifting on the grating by approximately ± 10 mm, which is nearly an entire period of the grating deformation function.…”

Section: J-bandmentioning

confidence: 99%

“…One possible source of movement of the pupil position is the image slicer, which is described in detail in Tecza et al (2000). 18 A torsional deformation of a slicer mirror with a measured amplitude of 2 HeNe fringes (close to what could be expected based on measurements of the slicer mirrors; see Eisenhauer et al (2003) 1 for an example of a slicer interferogram) would result in the pupil shifting on the grating by approximately ± 10 mm, which is nearly an entire period of the grating deformation function. Both the asymmetry in the 25 mas pixel scale line profiles and the variation in line profile along a slitlet can be explained with a shift in the pupil (due to, for example, a torsion in the slicer mirrors) in combination with the grating deformation.…”

Section: J-bandmentioning

confidence: 99%

Complex spectral line profiles resulting from cryogenic deformation of the SINFONI/SPIFFI diffraction gratings

George

Gräff

Hartl

et al. 2017

J. Astron. Telesc. Instrum. Syst

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Abstract. The integral field spectrograph, spectrometer for infrared faint field imaging (SPIFFI), has complex line profile shapes that vary with wavelength and pixel scale, the origins of which have been sought since the instrument construction. SPIFFI is currently operational as part of SINFONI at the Very Large Telescope (VLT) and will be upgraded and incorporated into the VLT instrument enhanced resolution imager and spectrograph (ERIS). We conducted an investigation of the line profiles based on the measurements we could take with the instrument calibration unit, as well as laboratory measurements of spare SPIFFI optical components. Cryogenic measurements of a spare SPIFFI diffraction grating showed significant periodic deformation. These measurements match the cryogenic deformation expected from bimetallic bending stress based on a finite element analysis of the lightweighted grating blank. The periodic deformation of the grating surface gives rise to satellite peaks in the diffraction pattern of the grating. An optical simulation including the cryogenic grating deformation reproduces the behavior of the SPIFFI line profiles with both wavelength and pixel scale as measured with the instrument calibration unit. The conclusion is that cryogenic deformation of the diffraction gratings is responsible for the nonideal line profiles, and that the diffraction gratings should be replaced during the upgrade for optimal instrument performance. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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SPIFFI image slicer: revival of image slicing with plane mirrors

Cited by 13 publications

References 5 publications

SINFONI - Integral field spectroscopy at 50 milli-arcsecond resolution with the ESO VLT

SINFONI - Integral field spectroscopy at 50 milli-arcsecond resolution with the ESO VLT

The infrared imaging spectrograph (IRIS) for TMT: design of image slicer

Complex spectral line profiles resulting from cryogenic deformation of the SINFONI/SPIFFI diffraction gratings

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