&lt;title&gt;Binospec: a dual-beam wide-field optical spectrograph for the converted MMT&lt;/title&gt;

Fabricant, Daniel G.; Fata, Robert G.

doi:10.1117/12.316765

Cited by 13 publications

(6 citation statements)

References 1 publication

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“…We obtained spectroscopic follow-up observations of the quasar candidates with the MMT/Red Channel spectrograph (Schmidt et al 1989), MMT/MMIRS (McLeod et al 2012), MMT/Binospec (Fabricant et al 1998), Magellan/FIRE (Simcoe et al 2008), Magellan/LDSS3-C (Stevenson et al 2016), KECK/ DEIMOS (Faber et al 2003), LBT/MODS (Byard & O'Brien 2000), Gemini/GMOS (Hook et al 2004) and P200/DBSP (Oke & Gunn 1982), over ∼25 observing nights from 2016 April to 2018 July.…”

Section: Spectroscopic Observationsmentioning

confidence: 99%

Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ≲ z ≲ 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ∼ 6.7

Wang

Yang

Fan

et al. 2019

ApJ

160

136

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This is the third paper in a series aimed at finding reionization-era quasars with the combination of DESI Legacy imaging Surveys (DELS), the Pan-STARRS1 (PS1) Survey, and near-infrared imaging surveys, such as the UKIRT Hemisphere Survey (UHS), as well as the Wide-field Infrared Survey Explorer (WISE) mid-infrared survey. In this paper, we describe the updated quasar candidate selection procedure, report the discovery of 16 quasars at 6.4 z6.9 from an area of ∼13,020 deg 2 , and present the quasar luminosity function (QLF) at z∼6.7. The measured QLF follows F µ-L L 1450 1450 2.35 () in the magnitude range −27.6<M 1450 <−25.5. We determine the quasar comoving spatial density at á ñ z =6.7 and M 1450 <−26.0 to be 0.39±0.11 Gpc −3 and find the exponential density evolution parameter to be k=−0.78±0.18 from z∼6 to z∼6.7, corresponding to a rapid decline by a factor of ∼6 per unit redshift toward earlier epochs. This indicates that the rapid decline of quasar spatial density at z>5 that was found by previous works continues to z>6, at a rate significantly faster than the average decline rate between z∼3 and 5. We measured quasar comoving emissivity at z∼6.7, which indicates that high-redshift quasars are highly unlikely to make a significant contribution to hydrogen reionization. The broad absorption line quasar fraction at z6.5 is measured to be 22%. In addition, we also report the discovery of six additional quasars at z∼6 in the Appendix.

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Section: Spectroscopic Observationsmentioning

confidence: 99%

Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ≲ z ≲ 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ∼ 6.7

Wang

Yang

Fan

et al. 2019

ApJ

160

136

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“…Daniel Fabricant and others have reported success with a rather complex scheme involving oil coupled lenses with difficult lens materials, including Fluorite and table salt (NaCl). 46,47 Fig. 17 FPL lens that exploded in a coating chamber.…”

Section: Testing and Failure Predictionmentioning

confidence: 99%

Guidelines for predicting stress in cemented doublets undergoing temperature change: theory, practice, and data

Kaufman,

Frayer,

Malone

et al. 2024

Opt. Eng.

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This work explores quick predictive methods for calculating potentially risky stresses and deflections in cemented doublets experiencing temperature change that agree well with finite element analysis. There are three failure modes of interest: cohesive failure of the adhesive, delamination (surface bond failure or debonding), and glass fracture. Adhesive theory, confirmed by finite element analysis, predicts stress singularities that complicate interpretation of the stress calculations. The presence of a stress singularity indicates the breakdown of linear elastic assumptions, but damage initiation and stress singularities are related. The authors find that geometry details near a bond edge can exacerbate or minimize damage initiation and stress concentrations. Because the interpretation of the stress results is complicated, the authors investigated predicted stresses in doublets that have been successfully tested between −40°C and 85°C. This study found that the thermal strain ðΔT • ΔαÞ should be less than 189 ppm, where ΔT is the temperature excursion and Δα is the difference in the two glass coefficients of thermal expansion. If the thermal strain is equal to or greater than 189 ppm, further analysis and testing is warranted. But the authors also show that the fabrication process can significantly influence stress failure, particularly with large diameter doublets.

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“…The Binospec is a wide-field, moderate-dispersion optical spectrograph designed to be used at the f/5 focus of the converted (6.5 m) MMT (Fabricant, Fata, & Epps 1998). It will use aperture masks with multiple slitlets to perform multiobject spectroscopy of faint galaxies.…”

Section: Thermal Performance Of Initial Binospec Optical Designmentioning

confidence: 99%

Athermalizing Refractive Optics with Fluid Lenses

Fabricant

2002

PUBL ASTRON SOC PAC

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ABSTRACT. Astronomical optics may encounter a wide range of nighttime temperatures (∼Ϫ10ЊC to ϩ20ЊC) at mountaintop observatories. Complex refractive optics used in high-performance spectrographs and focal reducers may perform poorly at temperature extremes unless special care is taken in their design. Refocusing will not always restore image quality, and thermally induced focal length changes may introduce troublesome image motion. We describe the techniques that we have used to predict the thermal behavior of the Binospec Spectrograph, an instrument under development for the converted Multiple Mirror Telescope. This thermal analysis must account for (1) the change in optical power due to thermal expansion of the optical elements, (2) thermal variations in the refractive indices of the optical elements, and (3) element respacings due to the interplay between the thermal expansions of the optical elements and cell materials. Binospec's multiplets are fluid coupled to reduce the reflection losses that would occur at glass-air surfaces; to athermalize the Binospec optics, we form weak lenses in the optical coupling fluid within multiplets. The large variation of the coupling fluid's refractive index with temperature allows these weak fluid lenses to correct thermal changes in the optical elements and cell. This athermalization technique is attractive because it introduces no additional mechanical complexity.

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<title>Binospec: a dual-beam wide-field optical spectrograph for the converted MMT</title>

Cited by 13 publications

References 1 publication

Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ≲ z ≲ 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ∼ 6.7

Exploring Reionization-era Quasars. III. Discovery of 16 Quasars at 6.4 ≲ z ≲ 6.9 with DESI Legacy Imaging Surveys and the UKIRT Hemisphere Survey and Quasar Luminosity Function at z ∼ 6.7

Guidelines for predicting stress in cemented doublets undergoing temperature change: theory, practice, and data

Athermalizing Refractive Optics with Fluid Lenses

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