8 research outputs found
Polish device for FOCCoS/PFS slit system
The Fiber Optical Cable and Connector System, FOCCoS, for the Prime Focus
Spectrograph, PFS, is responsible for transporting light from the Subaru
Telescope focal plane to a set of four spectrographs. Each spectrograph will be
fed by a convex curved slit with 616 optical fibers organized in a linear
arrangement. The slit frontal surface is covered with a special dark composite,
made with refractory oxide, which is able to sustain its properties with
minimum quantities of abrasives during the polishing process; this stability is
obtained This stability is obtained by the detachment of the refractory oxide
nanoparticles, which then gently reinforce gently the polishing process and
increase its the efficiency. The surface roughness measured in several samples
after high performance polishing was about 0.01 microns. Furthermore, the time
for obtaining a polished surface with this quality is about 10 times less than
the time required for polishing a brass, glass or ceramic surface of the same
size. In this paper, we describe the procedure developed for high quality
polishing of this type of slit. The cylindrical polishing described here, uses
cylindrical concave metal bases on which glass paper is based. The polishing
process consists to use grid sequences of 30 microns, 12 microns, 9 microns, 5
microns, 3 microns, 1 micron and, finally, a colloidal silica on a chemical
cloth. To obtain the maximum throughput, the surface of the fibers should be
polished in such a way that they are optically flat and free from scratches.
The optical fibers are inspected with a microscope at all stages of the
polishing process to ensure high quality. The efficiency of the process may be
improved by using a cylindrical concave composite base as a substrate suitable
for diamond liquid solutions. Despite this process being completely by hand,
the final result shows a very high quality
Multi-fibers connectors systems for FOCCoS-PFS-Subaru
The Fiber Optical Cable and Connector System (FOCCoS), provides optical
connection between 2400 positioners and a set of spectrographs through optical
fibers cables as part of PFS instrument for Subaru telescope. The optical fiber
cable will be segmented in 3 parts along the route, cable A, cable B and cable
C, connected by a set of multi-fiber connectors. The company USCONEC produces
the multi-fiber connector under study. The USCONEC 32F model can connect 32
optical fibers in a 4 x 8 matrix arrangement. The ferrules are made of a
durable composite, Polyphenylene Sulfide (PPS) based thermoplastic. The
connections are held in place by a push-on/pull-off latch, and the connector
can also be distinguished by a pair of metal guide pins that protrude from the
front of the connector. Two fibers per connector will be used for monitoring
the connection procedure. It was found to be easy to polish and it is small
enough to be mounted in groups. Highly multiplexed instruments like PFS require
a fiber connector system that can deliver excellent optical performance and
reliability. PFS requires two different types of structures to organize the
connectors. The Tower Connector system, with 80 multi-fiber connectors, will be
a group of connectors for connecting cable B (Telescope Structure) with cable C
(Positioners Plate). The Gang Connector system is a group of 8 gang connectors,
each one with 12 multi-fibers connectors, for connecting cable B (Telescope
Structure) with cable A (Spectrograph). The bench tests with these connector
systems and the chosen fibers should measure the throughput of light and the
stability after many connections and disconnections. In this paper we describe
tests and procedures to evaluate the throughput and FRD increment. The lifetime
of the ferrules is also in evaluation
Slit device for FOCCoS, PFS, Subaru
The Fiber Optical Cable and Connector System, FOCCoS, subsystem of the Prime
Focus Spectrograph, PFS, for Subaru telescope, is responsible to feed four
spectrographs with a set of optical fibers cables. The light injection for each
spectrograph is assured by a convex curved slit with a linear array of 616
optical fibers. In this paper we present a design of a slit that ensures the
right direction of the fibers by using masks of micro holes. This kind of mask
is made by a technique called electroforming, which is able to produce a nickel
plate with holes in a linear sequence. The precision error is around 1micron in
the diameter and 1 micron in the positions of the holes. This nickel plate may
be produced with a thickness between 50 and 200 microns, so it may be very
flexible. This flexibility allows the mask to be bent into the shape necessary
for a curved slit. The concept requires two masks, which we call Front Mask,
and Rear Mask, separated by a gap that defines the thickness of the slit. The
pitch and the diameter of the holes define the linear geometry of the slit; the
curvature of each mask defines the angular geometry of the slit. Obviously,
this assembly must be mounted inside a structure rigid and strong enough to be
supported inside the spectrograph. This structure must have a CTE optimized to
avoid displacement of the fibers or increased FRD of the fibers when the device
is submitted to temperatures around 3 degrees Celsius, the temperature of
operation of the spectrograph. We have produced two models. Both are mounted
inside a very compact Invar case, and both have their front surfaces covered by
a dark composite, to reduce stray light. Furthermore, we have conducted
experiments with two different internal structures to minimize effects caused
by temperature gradients
Prime Focus Spectrograph - Subaru's future -
The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and
Redshifts (SuMIRe) project has been endorsed by Japanese community as one of
the main future instruments of the Subaru 8.2-meter telescope at Mauna Kea,
Hawaii. This optical/near-infrared multi-fiber spectrograph targets cosmology
with galaxy surveys, Galactic archaeology, and studies of galaxy/AGN evolution.
Taking advantage of Subaru's wide field of view, which is further extended with
the recently completed Wide Field Corrector, PFS will enable us to carry out
multi-fiber spectroscopy of 2400 targets within 1.3 degree diameter. A
microlens is attached at each fiber entrance for F-ratio transformation into a
larger one so that difficulties of spectrograph design are eased. Fibers are
accurately placed onto target positions by positioners, each of which consists
of two stages of piezo-electric rotary motors, through iterations by using
back-illuminated fiber position measurements with a wide-field metrology
camera. Fibers then carry light to a set of four identical fast-Schmidt
spectrographs with three color arms each: the wavelength ranges from 0.38
{\mu}m to 1.3 {\mu}m will be simultaneously observed with an average resolving
power of 3000. Before and during the era of extremely large telescopes, PFS
will provide the unique capability of obtaining spectra of 2400
cosmological/astrophysical targets simultaneously with an 8-10 meter class
telescope. The PFS collaboration, led by IPMU, consists of USP/LNA in Brazil,
Caltech/JPL, Princeton, & JHU in USA, LAM in France, ASIAA in Taiwan, and
NAOJ/Subaru.Comment: 13 pages, 11 figures, submitted to "Ground-based and Airborne
Instrumentation for Astronomy IV, Ian S. McLean, Suzanne K. Ramsay, Hideki
Takami, Editors, Proc. SPIE 8446 (2012)
Progress with the Prime Focus Spectrograph for the Subaru Telescope: a massively multiplexed optical and near-infrared fiber spectrograph
The Prime Focus Spectrograph (PFS) is an optical/near-infrared multi-fiber
spectrograph with 2394 science fibers, which are distributed in 1.3 degree
diameter field of view at Subaru 8.2-meter telescope. The simultaneous wide
wavelength coverage from 0.38 um to 1.26 um, with the resolving power of 3000,
strengthens its ability to target three main survey programs: cosmology,
Galactic archaeology, and galaxy/AGN evolution. A medium resolution mode with
resolving power of 5000 for 0.71 um to 0.89 um also will be available by simply
exchanging dispersers. PFS takes the role for the spectroscopic part of the
Subaru Measurement of Images and Redshifts project, while Hyper Suprime-Cam
works on the imaging part. To transform the telescope plus WFC focal ratio, a
3-mm thick broad-band coated glass-molded microlens is glued to each fiber tip.
A higher transmission fiber is selected for the longest part of cable system,
while one with a better FRD performance is selected for the fiber-positioner
and fiber-slit components, given the more frequent fiber movements and tightly
curved structure. Each Fiber positioner consists of two stages of
piezo-electric rotary motors. Its engineering model has been produced and
tested. Fiber positioning will be performed iteratively by taking an image of
artificially back-illuminated fibers with the Metrology camera located in the
Cassegrain container. The camera is carefully designed so that fiber position
measurements are unaffected by small amounts of high special-frequency
inaccuracies in WFC lens surface shapes. Target light carried through the fiber
system reaches one of four identical fast-Schmidt spectrograph modules, each
with three arms. Prototype VPH gratings have been optically tested. CCD
production is complete, with standard fully-depleted CCDs for red arms and
more-challenging thinner fully-depleted CCDs with blue-optimized coating for
blue arms.Comment: 14 pages, 12 figures, submitted to "Ground-based and Airborne
Instrumentation for Astronomy V, Suzanne K. Ramsay, Ian S. McLean, Hideki
Takami, Editors, Proc. SPIE 9147 (2014)
Wavefront sensor for ophthalmological use
Este trabalho descreve os passos envolvidos no desenvolvimento de um protótipo de aberroscópio para uso oftalmológico. Este instrumento faz incidir no fundo do olho humano um feixe luminoso de baixa potência e amostra, por meio do método de Hartmann, as frentes de onda da luz espalhada. A partir dos dados coletados, a forma das frentes de onda são reconstituídas e as aberrações eventualmente existentes no olho são calculadas e representadas por intermédio dos polinômios de Zernike. Aqui são expostos os fundamentos deste método, algumas das suas propriedades e limitações. Também é mostrada a caracterização funcional do protótipo desenvolvido, testando-o com elementos ópticos de propriedades conhecidasThis work describes the steps involved in the aberroscope prototype development for ophthalmological use. This instrument injects inside the human eye a low power light beam and sample, by Hartmann method, the wavefronts produced by ocular fundus light scattering. From collected data, the wavefront shape is reconstructed and the eye aberrations that eventually existent are calculated and adjusted by Zernike polynomials. Are discussed the method foundations, some of properties and limitations. Also the functional characterization of the developed prototype is shown, by testing it with optical elements of known propertie
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Slit device assembly of Prime Focus Spectrograph for Subaru telescope
The Fiber Optic Cable and Connector System, FOCCoS, is a set of optical cables to feed the Prime Focus Spectrograph, PFS, for Subaru telescope (inverted right perpendicular01,02inverted left perpendicular). The extremity responsible for delivering light to spectrographs is called, FCA, Fiber Cable A. Cable A is the cable installed at the Spectrograph side and consists of the Fiber Slit Assembly, FSA, the routing with its support and the Fiber Input Assembly, FIA. FSA is composed of a set of optical fibers arranged linearly on the Slit device and supported by the Frame, protected by segmented tubes and routed between strain relief boxes and the connection interface. FIA is composed by the Connector Bench (Gang Connector) that allow connection with Cable B, at the Subaru Telescope interface, to receive light from Cable C where the fibers end is coupled with microlens. As four Spectrographs are considered for PFS/Subaru, four units of Cable A are necessary. In this paper, we present in details of a complete FCA to be installed in the spectrograph bench. We discuss about the general design, methods used to manufacture the involved devices