Abstract
The Prime Focus Spectrograph (PFS) is an optical/near-infrared multifiber spectrograph with 2394 science fibers distributed across a 1.3-deg diameter field of view at the Subaru 8.2-m telescope. The wide wavelength coverage from 0.38 {\mu}m to 1.26 {\mu}m, with a resolving power of 3000, simultaneously strengthens its ability to target three main survey programs: cosmology, galactic archaeology and galaxy/AGN evolution. A medium resolution mode with a resolving power of 5000 for 0.71 {\mu}m to 0.89 {\mu}m will also be available by simply exchanging dispersers. We highlight some of the technological aspects of the design. To transform the telescope focal ratio, a broad-band coated microlens is glued to each fiber tip. A higher transmission fiber is selected for the longest part of the cable system, optimizing overall throughput; a fiber with low focal ratio degradation is selected for the fiber-positioner and fiber-slit components, minimizing the effects of fiber movements and fiber bending. Fiber positioning will be performed by a positioner consisting of two stages of piezo-electric rotary motors. The positions of these motors are measured by taking an image of artificially back-illuminated fibers with the metrology camera located in the Cassegrain container; the fibers are placed in the proper location by iteratively measuring and then adjusting the positions of the motors. Target light reaches one of the four identical fast-Schmidt spectrograph modules, each with three arms. The PFS project has passed several project-wide design reviews and is now in the construction phase.
Highlights
The Prime Focus Spectrograph (PFS)[1] is an optical/near-infrared multifiber spectrograph with 2394 science fibers (Fig. 1), and is scheduled to be mounted on the Subaru 8.2-m telescope
To simplify the design of the spectrograph, the F∕2.2 beam from the telescope wide field corrector (WFC) is increased to F∕2.8 by a microlens bonded to each fiber
Further details on individual PFS components can be found in separate, componentspecific SPIE conference papers viz.: fiber system,[4,5,6,7,8,9] fiber positioner[10] and prime focus instrument,[11] spectrograph,[12,13,14] Dewar and detector,[15,16,17,18] and metrology camera.[19]
Summary
The Prime Focus Spectrograph (PFS)[1] is an optical/near-infrared multifiber spectrograph with 2394 science fibers (Fig. 1), and is scheduled to be mounted on the Subaru 8.2-m telescope. Each spectrograph module has three color arms to cover a wide wavelength region from 0.38 μm to 1.26 μm, with a mean resolving power λ∕δλ of 3000 This resolution is optimal for spectroscopic surveys of fainter galaxies and stars, targeting cosmology, Galactic archaeology and galaxy/AGN evolution. Further details on individual PFS components can be found in separate, componentspecific SPIE conference papers viz.: fiber system,[4,5,6,7,8,9] fiber positioner[10] and prime focus instrument,[11] spectrograph,[12,13,14] Dewar and detector,[15,16,17,18] and metrology camera.[19] The subsystems are discussed in roughly the same order as the science light path through the instrument. In 2014 January, NAOJ/Subaru formally joined the project, and MPA, Germany joined later in 2014
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