Fibre-Multi-Object Spectrograph (FMOS) for Subaru Telescope

Kimura, Masahiko; Maihara, Toshinori; Iwamuro, Fumihide; Akiyama, Masayuki; Tamura, Naoyuki; Dalton, Gavin; Takato, Naruhisa; Tait, Philip J.; Ohta, Kouji; Eto, Shigeru; Mochida, Daisaku; Elms, Brian; Kawate, Kaori; Kurakami, Tomio; Moritani, Yuuki; Noumaru, Junichi; Ohshima, Norio; Sumiyoshi, Masanao; Yabe, Kiyoto; Brzeski, Jurek; Farrell, Tony; Frost, Gabriella; Gillingham, Peter; Haynes, Roger; Moore, Anna; Müller, Rolf; Smedley, Scott; Smith, Greg; Bonfield, D. G.; Brooks, C.B.; Holmes, A.; Lake, Emma Curtis; Lee, Hanshin; Lewis, Ian; Froud, Tim R.; Tosh, Ian; Woodhouse, Guy F.W.; Blackburn, Colin; Dipper, N. A.; Murray, Graham J.; Sharples, R. M.; Robertson, David J.

doi:10.1117/12.461208

Cited by 20 publications

(11 citation statements)

References 4 publications

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“…Multimode fibers in fiber-fed spectrographs efficiently enable multiplexed observations of few hundreds objects per pointing. Current examples are the visible high-resolution spectrograph PEPSI on the LBT 74 or the near-IR fiber multi-object spectrograph FMOS on Subaru 75 .…”

Section: Importance Of Fibersmentioning

confidence: 99%

Astronomical photonics in the context of infrared interferometry and high-resolution spectroscopy

et al. 2016

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We review the potential of Astrophotonics, a relatively young field at the interface between photonics and astronomical instrumentation, for spectro-interferometry. We review some fundamental aspects of photonic science that drove the emergence of astrophotonics, and highlight the achievements in observational astrophysics. We analyze the prospects for further technological development also considering the potential synergies with other fields of physics (e.g. non-linear optics in condensed matter physics). We also stress the central role of fiber optics in routing and transporting light, delivering complex filters, or interfacing instruments and telescopes, more specifically in the context of a growing usage of adaptive optics.

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Section: Importance Of Fibersmentioning

confidence: 99%

Astronomical photonics in the context of infrared interferometry and high-resolution spectroscopy

et al. 2016

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“…For example, active space debris mitigation [13] seeks the strategies to detect space debris at long ranges. Since space debris radiate near-infrared waves, infrared fibers [14] can be used to detect them at the range of low earth orbit (LEO), which is an interesting region in view of debris mitigation. As another motivation, the number of available fibers may exceed the number of the desired targets to be observed.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Target Assignment to Robotic Fiber Positioner Systems

Macktoobian

Gillet

Kneib

2019

2019 Australian &Amp; New Zealand Control Conference (ANZCC)

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The target assignment methods applied to robotic fiber positioners are only applicable to homogeneous sets of targets to be observed. However, different batches of robotic fiber positioners available at the focal plane of a telescope can be simultaneously used in various applications. Those applications may be intrinsically different, say, some may seek astronomical observations, whereas the others may focus on space operations such as space debris detection. The current target assignment algorithms cannot handle these heterogeneous scenarios. This paper proposes an efficient multilinear algorithm to assign robotic fiber positioners to heterogeneous targets. We classify the targets based on their required exposure times. We also take the priority of observations compared to other operations into account during an assignment processes. Our algorithm assigns a bundle of robotic positioners to each dynamic target to efficiently detect it. We finally illustrate our algorithm's application using a simulated example.

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“…The OH suppression optics were followed by a low resolution spectrograph. Spectrographs as CIRPASS and FMOS 3 directly give low or high resolution spectra on a detector. The OH line light scattered between the lines by the spectrograph at high resolution is however not removed.…”

Section: Introductionmentioning

confidence: 99%

PRAXIS: low thermal emission high efficiency OH suppressed fibre spectrograph

Bland-Hawthorn

Ellis

Gers

et al. 2014

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation

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PRAXIS is a second generation instrument that follows on from GNOSIS, which was the first instrument using fibre Bragg gratings for OH suppression to be deployed on a telescope. The Bragg gratings reflect the NIR OH lines while being transparent to the light between the lines. This gives in principle a much higher signal-noise ratio at low resolution spectroscopy but also at higher resolutions by removing the scattered wings of the OH lines. The specifications call for high throughput and very low thermal and detector noise so that PRAXIS will remain sky noise limited even with the low sky background levels remaining after OH suppression. The optical and mechanical designs are presented. The optical train starts with fore-optics that image the telescope focal plane on an IFU which has 19 hexagonal microlenses each feeding a multi-mode fibre. Seven of these fibres are attached to a fibre Bragg grating OH suppression system while the others are reference/acquisition fibres. The light from each of the seven OH suppression fibres is then split by a photonic lantern into many single mode fibres where the Bragg gratings are imprinted. Another lantern recombines the light from the single mode fibres into a multi-mode fibre. A trade-off was made in the design of the IFU between field of view and transmission to maximize the signal-noise ratio for observations of faint, compact objects under typical seeing. GNOSIS used the pre-existing IRIS2 spectrograph while PRAXIS will use a new spectrograph specifically designed for the fibre Bragg grating OH suppression and optimised for 1.47 µm to 1.7 µm (it can also be used in the 1.09 µm to 1.26 µm band by changing the grating and refocussing). This results in a significantly higher transmission due to high efficiency coatings, a VPH grating at low incident angle and optimized for our small bandwidth, and low absorption glasses. The detector noise will also be lower thanks to the use of a current generation HAWAII-2RG detector. Throughout the PRAXIS design, from the fore-optics to the detector enclosure, special care was taken at every step along the optical path to reduce thermal emission or stop it leaking into the system. The spectrograph design itself was particularly challenging in this aspect because practical constraints required that the detector and the spectrograph enclosures be physically separate with air at ambient temperature between them. At present, the instrument uses the GNOSIS fibre Bragg grating OH suppression unit. We intend to soon use a new OH suppression unit based on multicore fibre Bragg gratings which will allow an increased field of view per fibre. Theoretical calculations show that the gain in interline sky background signal-noise ratio over GNOSIS may very well be as high as 9 with the GNOSIS OH suppression unit and 17 with the multicore fibre OH suppression unit.

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Fibre-Multi-Object Spectrograph (FMOS) for Subaru Telescope

Cited by 20 publications

References 4 publications

Astronomical photonics in the context of infrared interferometry and high-resolution spectroscopy

Astronomical photonics in the context of infrared interferometry and high-resolution spectroscopy

Heterogeneous Target Assignment to Robotic Fiber Positioner Systems

PRAXIS: low thermal emission high efficiency OH suppressed fibre spectrograph

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