Configurable slit-mask unit of the multi-object spectrometer for infra-red exploration for the Keck telescope: integration and tests

Spanoudakis, Peter; Giriens, Laurent; Henein, Simon; Lisowski, Leszek; O'Hare, Aidan; Onillon, E.; Schwab, Philippe; Theurillat, P.

doi:10.1117/12.789017

Cited by 7 publications

(5 citation statements)

References 3 publications

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“…MOSFIRE's optical system was designed by Harland Epps (UCSC) and the optical system was aligned and assembled using UCLA's Coordinate Measuring Machine (CMM) under the leadership of Nick Konidaris 4 . The CSU was designed and developed by CSEM, the Swiss Center for Electronics and Microtechnology 5 . MOSFIRE was shipped to the Observatory after its tenth cool down in the lab.…”

Section: Summary Of the As-built Designmentioning

confidence: 99%

MOSFIRE, the multi-object spectrometer for infra-red exploration at the Keck Observatory

et al. 2012

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This paper describes the as-built performance of MOSFIRE, the multi-object spectrometer and imager for the Cassegrain focus of the 10-m Keck 1 telescope. MOSFIRE provides near-infrared (0.97 to 2.41 m) multi-object spectroscopy over a 6.1' x 6.1' field of view with a resolving power of R~3,500 for a 0.7" (0.508 mm) slit (2.9 pixels in the dispersion direction), or imaging over a field of view of ~6.9' diameter with ~0.18" per pixel sampling. A single diffraction grating can be set at two fixed angles, and order-sorting filters provide spectra that cover the K, H, J or Y bands by selecting 3 rd , 4 th , 5 th or 6 th order respectively. A folding flat following the field lens is equipped with piezo transducers to provide tip/tilt control for flexure compensation at the <0.1 pixel level. Instead of fabricated focal plane masks requiring frequent cryo-cycling of the instrument, MOSFIRE is equipped with a cryogenic Configurable Slit Unit (CSU) developed in collaboration with the Swiss Center for Electronics and Microtechnology (CSEM). Under remote control the CSU can form masks containing up to 46 slits with ~0.007-0.014 precision. Reconfiguration time is < 6 minutes. Slits are formed by moving opposable bars from both sides of the focal plane. An individual slit has a length of 7.0" but bar positions can be aligned to make longer slits in increments of 7.5. When masking bars are retracted from the field of view and the grating is changed to a mirror, MOSFIRE becomes a wide-field imager. The detector is a 2K x 2K H2-RG HgCdTe array from Teledyne Imaging Sensors with low dark current and low noise. Results from integration and commissioning are presented.

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Section: Summary Of the As-built Designmentioning

confidence: 99%

MOSFIRE, the multi-object spectrometer for infra-red exploration at the Keck Observatory

et al. 2012

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“…2. Reconfigurable Slits: A near-infrared multi-object spectroscopy target selection system which has been successfully deployed on the ground-based MOSFIRE instrument at Keck is the Configurable Slit Unit (CSU) [126]. This is a form of micro-mechanical system which employs voice-coil actuated "inch-worm" motors to position up to 46 slitlets (each 5 mm long) in a 4 × 4 field.…”

Section: Reconfigurable Focal Planes For Space Applicationsmentioning

confidence: 99%

Chronos: A NIR spectroscopic galaxy survey to probe the most fundamental stages of galaxy evolution

et al. 2021

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We propose a dedicated, ultra-deep spectroscopic survey in the near infrared (NIR), that will target a mass-limited sample of galaxies during two of the most fundamental epochs of cosmic evolution: the formation of the first galaxies (at z 6; comsmic dawn), and at the peak of galaxy formation activity (at redshift z∼1-3; cosmic noon). By way of NIR observations (λ=0.8-2μm), it is possible to study the UV Lyman-α region in the former, and the optical rest-frame in the latter, allowing us to extract fundamental observables such as gas and stellar kinematics, chemical abundances, and ages, providing a unique legacy database covering these two crucial stages of cosmic evolution. The need to work in the NIR at extremely low flux levels makes a ground-based approach unfeasible due to atmospheric emission and absorption. Only with the largest facilities of the future (e.g. ELT) will be possible to observe a reduced set of targets, comprising at most of order thousands of galaxies. Likewise, from space, the small field of view of JWST and its use as a general purpose facility will yield a rather small set of high quality NIR spectra of distant galaxies (in the thousands, at best). Our project (codename Chronos) aims to produce ∼1 million high quality spectra, with a high S/N in the continuum, where information about the underlying stellar populations is encoded. The main science drivers are: I. Ferreras

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“…Thin retaining rings constrain the bearings axially but act as springs during cool down, again to compensate for differential CTE's. The CSU is described in detail by Spanoudakis et al elsewhere in these Proceedings 4 . Briefly, a slit is formed at a designated position within the FOV by positioning two opposing bars so as to create a rectangular opening.…”

Section: Mechanical Designmentioning

confidence: 99%

MOSFIRE: a multi-object near-infrared spectrograph and imager for the Keck Observatory

et al. 2008

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MOSFIRE, the multi-object spectrometer for infra-red exploration, is a near-IR (0.97-2.45 micron) spectrograph and imager for the Cassegrain focus of the Keck I telescope. The optical design provides imaging and multi-object spectroscopy over a field of view (FOV) of 6.14' x 6.14' with a resolving power of R~3,270 for a slit width of 0.7 arc seconds (2.9 pixels along dispersion). The detector is a 2.5 micron cut-off 2K x 2K H2-RG HgCdTe array with a SIDECAR ASIC for detector control. A special feature of MOSFIRE is that its multiplex advantage of up to 46 slits is achieved using a cryogenic Configurable Slit Unit (developed in collaboration with the Swiss Centre for Electronics and Micro Technology) reconfigurable under remote control in <5 minutes without thermal cycling. Slits are formed by moving opposable bars from both sides of the focal plane. An individual slit has a length of ~7.1 arc seconds but bar positions can be aligned to make longer slits. A single diffraction grating in two positions along with order-sorting filters gives essentially full coverage of the K, H, J and Y bands using 3 rd , 4 th , 5 th or 6 th order respectively. The grating and a mirror are mounted back-to-back, and when the bars are retracted from the FOV MOSFIRE becomes a wide-field imager. A piezo tip-tilt mirror following the field lens is used to provide flexure compensation at the 0.1 pixel level. Two large CCR heads allow the instrument to reach operating temperature in ~7 days. MOSFIRE is currently in construction.

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Configurable slit-mask unit of the multi-object spectrometer for infra-red exploration for the Keck telescope: integration and tests

Cited by 7 publications

References 3 publications

MOSFIRE, the multi-object spectrometer for infra-red exploration at the Keck Observatory

MOSFIRE, the multi-object spectrometer for infra-red exploration at the Keck Observatory

Chronos: A NIR spectroscopic galaxy survey to probe the most fundamental stages of galaxy evolution

MOSFIRE: a multi-object near-infrared spectrograph and imager for the Keck Observatory

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