The CCD282 is a large low-light level (L3 - Electron multiplying CCD) imaging sensor developed by e2v technologies for the University of Montreal. The intended use is for photon counting and very low light level imaging. The device will be used on the 3DNTT instrument which is a scanning Fabry-Perot interferometer. There is also the intention to place a device on a 10m class telescope for scanning Fabry-Perot application. This sensor is the largest electron multiplying CCD device produced to date with a 4k×4k backside illuminated frame transfer architecture. The sensor uses 8 parallel EM (Electron Multiplying) amplified outputs to maximize throughput. This paper present the first results and performance measurements of this device, and especially of the clock induced charge (CIC) which is one order of magnitude lower than previous devices thanks to a specific design optimized for photon counting operation.
The following article describes the coatings of both Fabry-Perot (FP) etalons to be installed in the integral
field spectrometer 3D-NTT. This simultaneous use of two FP etalons of high and low resolution respectively
is the new concept upon which the 3D-NTT is built. Design and fabrication of the coatings of those etalons is
a critical step to be able to achieve the desired performances of the instrument. More precisely, these etalons
will have to show less than a 10% variation of the finesse from 370 to 900nm and a better than lambda/100
cumulative optical uniformity over a Ø100mm surface. The aim is thus to design high-reflectivity coatings for
each of the FP etalon. The design process of the two sets of coatings will be described first, then the expected
performances of each etalon will be presented and finally the progresses in the making of these coatings will be
discussed.
The 3D-NTT is a visible integral field spectro-imager offering two modes. A low resolution mode (R ~ 300 to 6 000)
with a large field of view Tunable Filter (17'x17') and a high resolution mode (R ~ 10 000 to 40 000)
with a scanning Fabry-Perot (7'x7'). It will be operated as a visitor instrument on the NTT from 2009.
Two large programmes will be led: "Characterizing the interstellar medium of nearby galaxies with 2D maps of
extinction and abundances" (PI M. Marcelin) and "Gas accretion and radiative feedback in the early universe" (PI J.
Bland Hawthorn). Both will be mainly based on the Tunable Filter mode. This instrument is being built as a
collaborative effort between LAM (Marseille), GEPI (Paris) and LAE (Montreal). The website adress of the instrument
is : http://www.astro.umontreal.ca/3DNTT
GHαFaS is a new Fabry-Perot system available at the William Herschel Telescope. It was mounted, for the first
time, at the Nasmyth focus of the 4.2 m WHT in La Palma in 2007 July. With a spectral resolution of the order
R~15000 and a seeing limited spatial resolution, GHαFaS provides a new look at the Hα-emitting gas over a 4
arcminutes circular field in the nearby universe. Many types of objects can be observed with a scanning Fabry-Perot system on a 4.2 m class telescope such as galaxies, HII regions, planetary nebulae, supernova remnants
outflows from stars and the diffuse interstellar medium. Astronomers from the Laboratoire d'Astrophysique
Experimentale (LAE) in Montreal, the Laboratoire d'Astrophysique de Marseille (LAM), and the Instituto de
Astrofisica de Canarias (IAC), have inaugurated GHαFaS by studying in detail the dynamics of nearby spiral
galaxies. A robust set of tools for reducing and analyzing the data cubes obtained with GHαFaS has also been
developed.
The Smart Tunable Filter is a new spectrograph providing a continuous field of view of 4'×4' sampled at 56 mas using
the technology of imaging Bragg Tunable Filter (BTF) and a scanning Fabry-Perot tunable filter. 48 holographic gratings
photoinscripted helicoidally in a doped glass cylinder and preceded by 4 tunable BTF are used to study 52 emission lines
selected between the main OH night sky lines. The Smart Tunable Filter offers the advantage to be an "opto-ecological"
system providing a complete separation between spectral and spatial information avoiding problems from image slicing
and slit effects. The design can fully operate at cryogenic temperatures for IR purpose. The Fabry-Perot mode operates at
a spectral resolution of 5000 and can be removed to provide a 100 spectral resolution over the 48 fixed gratings. Main
results obtained in laboratory from the first prototype developed in collaboration with Photon etc. Inc. are presented.
Merit factors to compare this instrument to similar ones are studied versus sciences cases.
KEYWORDS: Electron multiplying charge coupled devices, Photon counting, Signal to noise ratio, Charge-coupled devices, Photons, Clocks, Quantum efficiency, Temperature metrology, Signal processing, Interference (communication)
CCCP, a CCD Controller for Counting Photons, is presented. This new controller uses a totally new clocking architecture
and allows to drive the CCD in a novel way. Its design is optimized for the driving of EMCCDs at up to 20MHz of pixel
rate and fast vertical transfer. Using this controller, the dominant source of noise of EMCCDs at low flux level and high
frame rate, the Clock Induced Charges, were reduced to 0.001 - 0.0018 electron/pixel/frame (depending of the electron
multiplying gain), making efficient photon counting possible. CCCP will be deployed in 2009 on the ESO NTT through
the 3D-NTT1 project and on the SOAR through the BTFI project.
KEYWORDS: Signal to noise ratio, Electron multiplying charge coupled devices, Signal processing, Charge-coupled devices, Photon counting, Quantum efficiency, Digital signal processing, Numerical simulations, Amplifiers, Interference (communication)
Thorough numerical simulations were run to test the performance of three processing methods of the data coming out from an electron multiplying charge coupled device (EMCCD), or low light level charge coupled device (L3CCD), operated at high gain, under real operating conditions. The effect of read-out noise and spurious charges is tested under various low flux conditions (0.001 event/pixel/frame< f < 20 events/pixel/frame). Moreover, a method for finding the value of the gain applied by the EMCCD amplification register is also developed. It allows one to determine the gain value to an accuracy of a fraction of a percent from dark frames alone.
Theoretically, L3CCDs are perfect photon counting devices promising high quantum efficiency (~90%) and sub-electron readout noise (σ<0.1 e-). We discuss how a back-thinned 512x512 frame-transfer L3CCD (CCD97) camera operating in pure photon counting mode would behave based on experimental data. The chip is operated at high electromultiplication gain, high analogic gain and high frame rate. Its performance is compared with a modern photon counting camera (GaAs photocathode, QE ~28%) to see if L3CCD technology, in its current state, could supersede photocathode-based devices.
KEYWORDS: Charge-coupled devices, Digital signal processing, Quantum efficiency, Telescopes, Gallium arsenide, Cameras, Signal to noise ratio, Fabry–Perot interferometers, Image intensifiers
We present a third generation instrument using a photon counting camera (IPCS) based on an GaAs photo cathode that can achieve quantum efficiency up to 28%, comparable to a thick CCD, but without readout noise. This system is 10 times more sensitive at the Hα wavelength than previous Fabry Perot system used at the Observatoire du mont Mégantic. In terms of S/N ratio, the system outperforms CCD for extremely faint fluxes, included AR coated low noise thin CCDs. This system offers up to 1k x 1k pixels which is the largest monolithic IPCS. An original cooling system is used for camera based on a Ranque-Hilsh vortex tube. The real-time centering is done by a scalable DSP board. FaNTOmM is the association of a focal reducer (PANORAMIX: the 1.6m mont Megantic OmM telescope focal reducer), a Fabry Perot etalon and an IPCS. Preliminary results obtained with the 1.6m mont Megantic telescope are presented.
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