Development of a cryogenic system for the VIRUS array of 150 spectrographs for the Hobby-Eberly Telescope

Chonis, Taylor S.; Vattiat, Brian L.; Hill, Gary J.; Marshall, J. L.; Cabral, Kris; DePoy, D. L.; Smith, Michael P.; Good, John M.; Booth, John A.; Rafal, Marc D.; Savage, Richard

doi:10.1117/12.857362

Cited by 13 publications

(20 citation statements)

References 10 publications

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“…We have made extensive tests on prototypes, applying heat loads to the bayonet, which have performed very well 46 . The temperature rise across the connection is ΔT ~ 1.8 K/Watt of load at 80 K. Modeling of the full thermal path has been undertaken, under the requirement of having the CCD temperature at -140 C, with no heater power.…”

Section: Cryogenic Systemmentioning

confidence: 99%

“…The distributed layout of the VIRUS array presents a significant challenge for the cryogenic design 50,46 . Allowing 5 W heat load for each detector, with all losses accounted for and a 50% margin, the cooling source is required to deliver 3,600W of cooling power.…”

Section: Cryogenic Systemmentioning

confidence: 99%

“…5.1 and Ref. 46. The cryostat is composed of two aluminum castings, postmachined on critical mount surfaces and flanges.…”

Section: Virus Production Optomechanical Designmentioning

confidence: 99%

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VIRUS: a massively replicated 33k fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

et al. 2010

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The Visible Integral-field Replicable Unit Spectrograph (VIRUS) consists of a baseline build of 150 identical spectrographs (arrayed as 75 units, each with a pair of spectrographs) fed by 33,600 fibers, each 1.5 arcsec diameter, deployed over the 22 arcminute field of the upgraded 10 m Hobby-Eberly Telescope (HET). The goal is to deploy 96 units. VIRUS has a fixed bandpass of 350-550 nm and resolving power R~700. VIRUS is the first example of industrial-scale replication applied to optical astronomy and is capable of spectral surveys of large areas of sky. The method of industrial replication, in which a relatively simple, inexpensive, unit spectrograph is copied in large numbers, offers significant savings of engineering effort, cost, and schedule when compared to traditional instruments.The main motivator for VIRUS is to map the evolution of dark energy for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX ‡ ) using 0.8M Lyman-α emitting galaxies as tracers. The full VIRUS array is due to be deployed in late 2011 and will provide a powerful new facility instrument for the HET, well suited to the survey niche of the telescope. VIRUS and HET will open up wide field surveys of the emission-line universe for the first time. We present the design, cost, and current status of VIRUS as it enters production, and review performance results from the VIRUS prototype. We also present lessons learned from our experience designing for volume production and look forward to the application of the VIRUS concept on future extremely large telescopes (ELTs). * The Hobby -Eberly Telescope is operated by McDonald Observatory on behalf

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Section: Cryogenic Systemmentioning

confidence: 99%

Section: Cryogenic Systemmentioning

confidence: 99%

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VIRUS: a massively replicated 33k fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

et al. 2010

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“…The enclosure ports for LRS2 will also contain some additional infrastructure that is not required for a VIRUS spectrograph pair (e.g., AC power and electronics racks for mounting the hardware and controllers for the vacuum equipment). The VIRUS Support Structure also supports the extensive liquid nitrogen distribution system 38,59 that is utilized to keep the CCDs contained in the 75 VIRUS spectrograph pairs and the two LRS2 spectrograph pairs cool. At the top of each enclosure pair is a header tank, which provides a continuous flow of cryogen to the various lateral levels of vacuum jacketed pipes.…”

Section: Lrs2-b and Lrs2-r At The Hetmentioning

confidence: 99%

LRS2: the new facility low resolution integral field spectrograph for the Hobby-Eberly telescope

et al. 2014

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The second generation Low Resolution Spectrograph (LRS2) is a new facility instrument for the Hobby-Eberly Telescope (HET). Based on the design of the Visible Integral-field Replicable Unit Spectrograph (VIRUS), which is the new flagship instrument for carrying out the HET Dark Energy Experiment (HETDEX), LRS2 provides integral field spectroscopy for a seeing-limited field of 12 ×6 . For LRS2, the replicable design of VIRUS has been leveraged to gain broad wavelength coverage from 370 nm to 1.0 µm, spread between two fiber-fed dualchannel spectrographs, each of which can operate as an independent instrument. The blue spectrograph, LRS2-B, covers 370 ≤ λ (nm) ≤ 470 and 460 ≤ λ (nm) ≤ 700 at fixed resolving powers of R = λ/δλ ≈ 1900 and 1100, respectively, while the red spectrograph, LRS2-R, covers 650 ≤ λ (nm) ≤ 842 and 818 ≤ λ (nm) ≤ 1050 with both of its channels having R ≈ 1800. In this paper, we present a detailed description of the instrument's design in which we focus on the departures from the basic VIRUS framework. The primary modifications include the fore-optics that are used to feed the fiber integral field units at unity fill-factor, the cameras' correcting optics and detectors, and the volume phase holographic grisms. We also present a model of the instrument's sensitivity and a description of specific science cases that have driven the design of LRS2, including systematically studying the spatially resolved properties of extended Lyα blobs at 2 < z < 3. LRS2 will provide a powerful spectroscopic follow-up platform for large surveys such as HETDEX.

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“…The mechanical section view in Figure 2 shows the IFU slit sub-assembly mounted to the collimator sub-assembly on the left, and the camera sub-assembly mounted on the right [12] . The CCD is cooled by a flexible line from above with a breakable cryogenic bayonet connection [13] . The spot diagram of the VIRUS unit spectrograph is shown in Figure 3.…”

Section: Overviewmentioning

confidence: 99%

Visible Integral-field Replicable Unit Spectrograph (VIRUS) optical tolerance

et al. 2010

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The Visible Integral-field Replicable Unit Spectrograph (VIRUS) instrument is made up of 150+ individually compact and identical spectrographs, each fed by a fiber integral field unit. The instrument provides integral field spectroscopy from 350 nm to 550 nm of over 33,600 spatial elements per observation, each 1.8 arcsec 2 on the sky, at R ~ 700. The instrument will be fed by a new wide-field corrector (WFC) of the Hobby-Eberly Telescope (HET † ) with increased science field of view as large as 22 arcmin diameter and telescope aperture of 10 m. The construction of the large number of VIRUS units requires the individual spectrographs be interchangeable at sub-system level and a production line assembly process be utilized, while meeting the optical performance specification. These requirements pose a strong emphasis on careful analysis of the manufacturing and alignment tolerances of the unit spectrograph design. In this paper, we detail the tolerance analysis, and discuss its implication to the optical performance and production of the VIRUS instrument.

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Development of a cryogenic system for the VIRUS array of 150 spectrographs for the Hobby-Eberly Telescope

Cited by 13 publications

References 10 publications

VIRUS: a massively replicated 33k fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

VIRUS: a massively replicated 33k fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

LRS2: the new facility low resolution integral field spectrograph for the Hobby-Eberly telescope

Visible Integral-field Replicable Unit Spectrograph (VIRUS) optical tolerance

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