Technical Annex PHY00045 (Max 10 pages)
“Development of a photon counting high time resolution Stokes' polarimeter for
astronomical observation on future large telescopes and for optical science”
What is the question that this proposal addresses?
The question has two parts, both of them significant – a technological/scientific and an
astronomical/scientific part. We ask, ultimately, what is the short-term variability (with time
resolution ~100 μs, over a broad bandwidth of 500-900 nm) of the Stokes' vector in compact
astronomical sources such as pulsars, catalclysmic variable stars (CVs), gamma-ray bursts,
(GRBs), etc, because a knowledge of these variations will inform and constrain modelling of
the electrodynamic properties in these compact, and extreme, source regions.
However, as no suitable instrument exists, in the first part of the question, we must
first ask how to design and construct the Galway Stokes’ Polarimeter (GaSP) a high-speed
broad-band Stokes' polarimeter for astronomy. The design and construction of GaSP, which
will have unique capabilities for High Time Resolution Astrophysics represents a significant
scientific challenge in its own right, and will form the substantive part of the work for the first
two years of the project.
As a specific example to be answered in the second part we wish to investigate the
single pulse photo-polarimetric properties of the crab pulsar. This is, actually, a most
challenging example, requiring very high performance from GaSP, because random variations
– evidence for an underlying stochastic process - exist down to 100 μs. This is a very short
interval in which to measure polarisation, ruling out many conventional polarimeter designs.
Why is this problem significant?
The long term goal of this project is to enable measurements of random variability, at high
speed, of the full Stokes’ vector for a number of astrophysical sources – the significance of
these measurements is explained in this section. Within the three year limits of the project the
goals are (a) the development of GaSP, and (b) measurement of the random variability of the
crab pulsar down to 100 μs.
Development Of A High-Speed Stokes’ Photo-Polarimeter (GaSP)
Astronomical polarimetry has been a somewhat neglected area of astronomical observation mainly because it is rather difficult. Javier Trujillo-Bueno & Fernando Moreno-Insertis (eds)
in the Preface to “Astrophysical Spectropolarimetry, CUP, 2002, state “…The polarisation of
light is the key to unlocking many new discoveries and obtaining the information we need to
understand the physics of many phenomena occurring in the Universe….” A full description
of the polarisation state of a light beam requires a knowledge of 4 numbers (the components
of the Stokes’ vector, I,Q,U,V), namely, total intensity (I), intensity of linear polarisation in a
certain direction (Q), intensity of linear polarisation in a direction at 450 to that (U), and
intensity of the right or left handed circularly polarised component (V). Linear polarisation
gives us information on the degree of asymmetry present in the emission zone and/or
subsequent passage between source and observer. The prime causes of linear polarisation
include scattering and reflection as well as magnetic field structure in the source region in the
case of non-thermal radiation – such as synchrotron emission. The degree of polarisation and
the angle of polarisation constrains the geometry of the local magnetic field – knowledge of
which is crucial to increasing our understanding of GRBs, AGNs, CVs and isolated neutron
stars, including pulsars. Circular polarisation gives us information about magnetic fields.
Stokes' polarimetry is a powerful technique, used in the laboratory to measure the
properties of scattering surfaces and birefringent materials, and in astronomy to map out
magnetic fields (see, for example, "Stokes Imaging of the Acretion Region in Magnetic
Cataclysmic Variables - II V347 Pav", S.B.Potter, P.J.Hakala, Mark Cropper, MNRAS, 315,
423-430, 2000). Up to now Stokes’ photo-polarimetry has been limited to cases where there is
adequate light, and slow variation. In learning how to build GaSP we will be breaking new
ground because (a) the high speed requirement rules out rotating components, (b) the high
speed requirement (and consequent lack of photons) necessitates a high throughput and an
extremely wide bandwidth – ruling out modulated components (which are very chromatic),
and linear dichroic filters, etc., and (c) the high speed necessitates the use of a photoncounting detector.
The term high speed, describing the proposed instrument, is, of course, a relative one
and depends upon the context. A bandwidth of 10 kHz would not be described as high speed
for some tasks in instrumentation, but to measure the Stokes’ vector with this bandwidth is
very challenging indeed, particularly for faint sources and might justifiably be described as
“high speed”. An instrument capable of doing this will find many applications as the next
generations of 10-20m diameter and 30-100m diameter telescopes will provide the photon
fluxes needed to investigate many more objects, and for applications in other areas of science.
Investigation of Short Time Variability of the Stokes’ Vector in Pulsars, CVs, and GRBs
Pulsars
Most neutron stars are formed as one of the end points in the evolution of a massive star.
When a large star (one with a mass > 10 solar masses) exhausts its nuclear fuel it undergoes
core collapse that leads to a supernova explosion. During this explosion the central core is
compressed until its density approaches that of the atomic nucleus at this point it can be said
to be a neutron star. If at this stage it is of sufficient mass it should collapse further and form a
low mass black hole. Isolated neutron stars are normally observed as radio pulsars. The
preferred theory to describe their emission assumes that the radio pulses originate from
coherent interactions between the high-energy plasma and the strong magnetic field that
surrounds the pulsar and that the high energy emission from the infra-red to gamma-rays
results from processes such incoherent synchrotron. From the asymmetries in the production
process we expect this radiation to be polarised. Furthermore as the pulsars rotate with periods
ranging from a few milliseconds to a few seconds we require detectors that are sensitive at
short time scales and to polarisation levels of <1%. In the radio this is a relatively
straightforward process, but in the higher energy regime it is really only in the optical where
significant observations can be made with currently available technology. One of the
problems with pulsars studies has been our inability to determine the location of the emission
zone. The polarisation gives a good estimate of the relative orientation of the observer and the
local magnetic field. A possible solution to the problem can come from a mix of polarisation
studies of individual and coherently summed optical pulses and detailed geometric models
(see O’ Connor, PhD thesis, NUI, Galway 2004 and O’ Connor et al (2005) submitted to
MNRAS).
To extend this work we need the following
i)
good average polarisation measurements throughout the pulsar profile at a
level better than 0.5% based upon summed profiles
ii)
observations of the polarisation of individual optical pulses during giant radio
pulse events (see for example Shearer et al, Science, 301, 493(2003))
iii)
detailed geometrical models to combine the magnetic field structure and
plasma density with
For studies of pulsars we require a polarimeter that instantaneously measures all of the
Stokes parameters and not the time-averaged polarisation, which most systems determine. The
same can be said for observations of stochastic variability – e.g. CVs where the fluctuations in
the local plasma during flares and flickering events will generate short-lived local magnetic
fields that can cause variations in the polarisation. Here the polarisation observations are
measuring both the field strength and indirectly the density of the plasma.
Gamma-Ray Bursts
There are a number of possible explanations to the phenomena of gamma-ray bursts. To
explain initial fluctuations on time scales of milliseconds to seconds requires compact objects,
and neutron stars, either through coalescence or as part of their formation are normally part of
the model. In both of these scenarios the emission is likely to be in the form of an ultrarelativistic jet. The association of a supernova with GRB 030329 (Hjorth et al, 423, 847
(2003)) for example indicates that at least some GRBs are associated with a supernova event.
Studies of the polarisation of the early light curve of a GRB will give information about the
evolution of the jet as it ploughs into the local ISM. The polarisation comes in part from
inhomogeneities in the magnetic field as the strong magnetic field around the neutron star
breaks up or from dynamically created fields within the fireball (Lyutikov, astro-ph/0409489).
(Greiner et al (astro-ph/0312089) showed that polarisation was measurable in the range 1-3%
and consistent with turbulent behaviour at timescales of hours. Of interest will be what is the
minimum timescale observable with our proposed instrument. We will be sensitive to
polarisation variations of <1% using a 10m telescope (say SALT) at time scales of 10 second
for a 19th magnitude optical afterglow. From this we would be able to follow the evolution of
the polarisation and hence the evolution of the fireball or jet within a turbulent magnetic field.
Cataclysmic Variables
Cataclysmic Variables are a class of binary system where a main sequence star accretes
matter onto an evolved companion. The companion is normally a white dwarf. The orbital
period of the system ranges from several tens of minutes to hours. The rotational period of the
white dwarf will of the order of 100 seconds. The systems are characterised by turbulent flow
within the accretion disk that are modified by the reasonably strong magnetic fields (>104 G)
around the white dwarf to a few hundred Gauss within the disk. Our proposed system will be
sensitive to both studies of the white dwarf surface at time resolutions of 100s milliseconds to
short-time (<1µs) stochastic variability with the accretion disk. As with other studies
polarisation gives information related to the magnetic field – its variable geometry, lifetime
and strength. When this is combined with Doppler tomography to measure the physical
structure of the accretion disk and the associated magnetic field strength and orientation.
The Stokes’ Vector of the Crab Pulsar
We propose to measure the Stokes' vector for the Crab pulsar for individual pulses to ~100μs.
A small number of pulsars exhibit a giant radio pulse phenomena where the luminosity of the
pulsar dramatically increase for one pulse. This happens at random but is a significant event
with radio brightness temperatures in approaching of 1040K (Soglasnov et al, ApJ, 616, 439
(2004)). The origin of these pulses, which have widths down to a few nanoseconds, is
unknown but is likely to reflect some form of plasma instability or magnetic field pinching –
but the radiation must be coming from some coherent source. The physical size of the
emission region is of the order of metres. The Galway Group observed a slight optical
enhancement during GRP events from the Crab Pulsar (Shearer, Redfern, et al, Science, 301,
493, (2003)). These observations provided the first correlation between the strength of pulsar
radio emission and the optical flux – indicating at some level the processes or emissions zones
are linked. We need more observations to establish this correlation. We are interested in
studying the polarization of the optical flux during GRP events as an indicator of the local
magnetic field geometry. As this requires that the optical pulses are selected off-line for
comparison with radio GRP times we require the ability to measure instantaneously all
Stokes’ parameters so that we can measure the polarization sweep through an individual
pulse. No currently available instrument is capable of these measurements.
How will the question be answered? [Describe the experimental or theoretical
methodology, plus a brief project management plan, milestones and expected
output.]
We will use an investigation of the polarisation in individual pulses in the Crab Pulsar as a
demonstrator of GaSP. In order to address one half of the question - what is the magnetic field
distribution in the Crab pulsar during giant radio pulses? - it will be necessary to design and build a
verify a unique optical Stokes' polarimeter. This forms the complementary part of the question how does one do this?
Development of GaSP
The required properties of GaSP are defined by the demonstration problem.
The Crab pulse period is ~33 ms, having pulses ~1 ms wide. The source is bright – figure
(below) shows a train of 10 individual pulses obtained by our TRIFFID camera using the
Russian 6m Bolshoi Telescope in 2003, using a photon-counting photodiode detector. The
polarimetric accuracy (assuming <=100% efficiency) to be achieved may be extrapolated
(from Hofman et. al. 2002, Design Study for the PEPSI Polarimeter for the LBT) - 10% in
1ms at 6m diameter and 4% at 11m diameter, and hence 1% at 6m diameter by the coaddition of >100 optical pulses selected by coincidence with giant radio pulses.
 High DQE detectors must be used
 Linear dichroic filters, and other absorbing filters cannot be used
 An extremely broad bandwidth is necessitated – essentially as broad as is possible
within the constraints of detector cutoffs and the achromatism of optical components to maximise the signal from a flat spectrum source. Modulated components (such as
ferroelectric liquid crystal retarders) are intrinsically chromatic and cannot be used.
The optical pulses which we wish to investigate are those which coincide with the "giant radio
pulses", which occur randomly. The usual form of polarimeter simply will not work - see, for
example, "Optical Pulse Phased Polarimetry of PSR 0656+14", B.Kern et. al., Ap.J., 597,
1049-1058, 2003, in which a linear dichroic filter was slowly rotated, (so that there was
actually no measurement of Stokes' V at all) and in any case different phases of the repetitive
waveform were constructed by sampling. Individual random pulses must be observed so the
polarimeter needs an intrinsic high-speed time response. This means:
 Rotating components cannot be used within the required timescale (100 μs).
 A photon counting detector, and a time resolution of at least 100 μs must be used. This
rules out conventional CCDs.
We have identified in the literature, an unusual, but rather suitable polarimeter design.
("Broadband Division of Amplitude Polarimeter Based On Uncoated Prisms", E.Compain,
B.Drevillon, Appl.Opt., 37#25, 5938, 1998) Figure 1 shows a diagram of the arrangement.
They describe a laboratory instrument with excellent precision (<1%) over the spectral range
400-2000nm. The division of amplitude is due to reflection at an uncoated dielectric surface.
Intrinsically, this can be achromatic over a broad spectral range - limited only by dispersion
within the dielectric. Incoming light is divided into 2 beams by reflection from the top surface
of the prism. The internal beam experiences 2 internal reflections before being partially
reflected and partly absorbed on the bottom surface. The 2 external beams are further
beamsplit by polarising beamsplitters to produce the required 4 beams. The 2 internal
reflections act as a Fresnel rhomb-type retarder to allow the Stokes' vector to be obtained by
inversion of the output vector. In the original design the input beam S(t) is a single accurately
collimated beam.
Starting in September 2004, we have been conducting an intensive theoretical study,
modellisation and laboratory investigation of this Stokes’ polarimeter design in collaboration
with the original authors (from the Ecole Polytechnique, Paliseau, France). This will be
completed before the start of this project.
We have shown (Golden et al, A&A, 363, p617, 2000) that aperture photometry of faint
sources in the presence of background and variable atmospheric properties (seeing) is best
achieved, in fact, by using an imaging detector capable of resolving a small region
encompassing both the source (an aperture defined in software), and a comparison
background region, under all conditions of seeing, telescope wobble, etc., rather than a
physical aperture The reasons for this are as follows:
 One is able, post-exposure, to determine the, variable, optimum aperture size to
maximise the signal-to-noise adaptively during the observation.
 One is able, post-exposure, to track movements of the aperture centroid (due to seeing
and also wobble) and to select from the data stream only photons falling within this
aperture.
 A physical (rather than software) aperture cannot be optimised and must be
sufficiently large to ensure that the target is easily acquired, and that 100% of the
target photons are intercepted - otherwise, seeing-induced variations in brightness will
occur, which are damaging to high precision time series analysis. A software-defined,
adaptive aperture can therefore be smaller than a fixed, physical aperture, and can
consistently give optimum signal to noise.
 One is able to select, post-exposure, background photons from a comparable region
close to the adaptive aperture. This is always essential in order to achieve accurate
photometry, but is even more important when background polarisation may be
variable across the field.
Our (optimised) DOAP has the required properties for GaSP, namely,
 Wide bandwidth, at least as wide as available detector bandwidths (500-900 nm for a
GaAs photocathode).
 Static components, and division of almost 100% of the light into four, equal intensity,
individually detected, external beams.
 Minimisation of the effects of photon noise on the inversion of the output vector.
 The ability to invert the output vector with precision for a small range of input angles
for S(t) corresponding to collimated beams from an image region of 10”-15” on the
sky – 2-30 in the collimated beam - depending upon the telescope used. This will
enable the polarisation vector across a small image field to be determined.
 The ability to re-image the four output beams into small sub-images on a single
imaging photon-counting detector.
The choice of detector is crucial for this project. We have, for two years, been in
collaboration with the Experimental Astrophysics Group in the Space Sciences Laboratory of
the University of California, Berkeley (Professor Oswald Siegmund, and Dr Barry Walsh).
This has resulted in a successful collaborative proposal to NSF, namely, “The Development
of A Novel Photon Counting GaAs Detector for Sub-millisecond Astronomy”, in which we
have the responsibility to test the new detector using our current high time resolution
photometer – called NGTriffid, developed under the Enterprise Ireland Basic Research
Scheme. As a consequence, we propose to utilise the detector type being developed under this
grant, which will become available during the second year of this proposal. The tube and
electronic units will be purchased under the supervision of SSL, Berkeley, and they will
supply all software free of charge.
Fig. 2. GaAs photocathode QE’s showing blue extended cathode options.
The detector is based upon their successful delay line, 2-d, anode plane electron
readout scheme, which has now been used for several space missions. Their readout scheme
generates 1000*1000 pixel resolution on a 25mm photocathode, with a time resolution less
than 2 ns, a maximum counting rate in excess of 1 Mcps, and a maximum pixel counting rate
in excess of 100 cps when used with the latest “hot” channel multiplier arrays. These figures
are easily compatible with the requirements of GaSP. The critical issue is of cathode
sensitivity, and an important feature of the NSF grant is a collaboration with outside
contractors (namely, Burle Industries) able to deliver high efficiency GaAs photocathodes
(see figure 2, above), which meet the GaSP requirements.
We have investigated alternative detectors. At first sight electron multiplying CCDs
(such as the iXon cameras offered by Andor Instruments based upon the E2V L3 or TI
Impactron chips) seem to offer superior performance in terms of quantum efficiency. For the
GaSP the Berkeley GaAs cameras offer superior performance because EMCCDs are not event
counting. In order to achieve the minimum 100 μs time resolution it would be necessary to
read out data at the maximum 35 M pixel/sec, and also to read out a tiny sub-frame (64*16
pixels). We have discussed this with Andor Instruments. In order to mitigate the effect of
spurious events due to Clock Induced Charge it would be necessary to use a tiny chip – Andor
have available a suitable prototype TI chip (RQE of ~60%) of 128*64 pixels and would be
willing to produce a camera on a collaborative basis. With this small sub-frame it would be
necessary to use a small plate scale (say 1.5”/pixel) to achieve the necessary 15” field. This
means that all of the events would be concentrated into a few pixels, and, even at
35Mpixel/sec, there could be up to several hundred photons/pixel at peak. This is highly
undesirable for an EMCCD because avalanche multiplication noise at these rates reduces the
DQE to ~30%, which is somewhat inferior to that of the Berkeley image cameras. However,
whilst we have decided to use the Berkeley camera, the availability of the EMCCD solution
provides a comforting backup in case of any unforeseen difficulties.
Observation of the Random Variation in the Crab Pulsar
Investigations of the magnetic field geometry in the Crab pulsar for pulses coincident with
giant radio pulses will form the subject of observations on the 6m telescope - to which we
have access - during the verification phase, and other telescopes at a later phase. Pottter at al
and O’Connor (refs above) describe the Stokes' mapping technique which we will apply. The
degree of polarisation (particularly Stokes' V for which we will make the first observations in
this time regime) and the angle of linear polarisation constrains the geometry of the local
magnetic field. Polarisation is essential to understanding the Crab pulsar because its
properties are dominated by its strong magnetic field. Kern et. al. (2003) published linear,
averaged, polarimetry of the Crab. They account for gross features of the optical light curve in
terms of models of the emission but were unable to distinguish between them or, obviously, to
explain the connection between the Giant Radio Pulse phenomenon and enhanced optical
emission. Using Stokes' mapping it should be possible to restrict the emission zone geometry
and to detect the polarisation of the (very faint) thermal emission during the interpulse
induced by the dense magnetised atmosphere. The ability to do this will be crucial to
understanding other isolated neutron stars which are not pulsars.
Work Plan & Responsibility
The PI remains in overall responsibility for the construction, calibration and use of GaSP, but
the Co-Is (1-JCD, 2-AS, 3-MND) and the PDRA will share responsibility, as indicated below.
Monthly progress meetings will be held, but day to day collaboration is simplified by the fact
that we are all in the same Institution, and we have collaborated for more than 10 years.
WP1 Construction and calibration of laboratory prototype Stokes’ polarimeter
Start: September 2005
Duration 12 months Responsible PI + Co-I 1 (JCD)
This WP builds upon the current work, and will tackle the crucial issue of reliable calibration.
WP2 Design, construction & calibration of final GaSP polarimeter module
Start: March 2006
Duration 12 months Responsible PI + Co-I 1 (JCD)
This WP uses WP1 and designs, constructs, calibrates the final polarimeter, in which the 4 output
beams are folded onto a single imaging photon-counting detector – we will use an available CCD
camera to verify the performance at this stage.
WP3 Mechanical design and construction of GaSP
Start September 2005
Duration 18 months Responsible PI + Co-I 3 (MND)
This WP provides the essential mechanical precision and stability to allow the GaSP polarimeter to
be calibrated in the laboratory and remain calibrated when in use on a telescope. It is essential that
the design and construction be of the highest professional standards to ensure access to large
telescopes.
WP4 Recruitment of PDRA
Start September 2005
Duration 6 months
Responsible PI
WP5 Electronic design and construction of GaSP, including control, data collection & storage
Start March 2006
Duration 18 months Responsible PI, PDRA, Co-I 2 (AS)
This WP builds upon the experience of using NGTriffid with imaging photon-counting detectors
WP6 Construction and integration of Berkeley GaAs detector into GaSP
Start March 2006
Duration 18 months Responsible PI, PDRA, Co-I 2, 3 (AS, MND)
SSL Berkeley will provide a final image tube, specifications of electronics (mostly commercial),
and full software support. This WP makes a custom housing for the detector head, integrates and
tests the system, and integrates it into GaSP
WP7 Software design for GaSP, updated NGTriffid data collection system
Start March 2006 Duration 18 months Responsible PI, PDRA, Co-I 2 (AS), Co-I 3 (MND)
This WP builds upon the experience of using NGTriffid with imaging photon-counting detectors
WP8 Integration & testing of GaSP
Start September 2007
Duration 6 months
Responsible PI, Co-I 2 (AS), Co-I 3 (MND)
This WP tests, and calibrates the whole system in the laboratory, prior to use on a large telescope
WP9 Initial observations on a large telescope
Start March 2008
Duration 6 months
Responsible PI, Co-I 2 (AS), Co-I 3 (MND)
In this WP we will test the GaSP on a large telescope. Whilst time on other large telescopes will be
sought - and we have a track record of achievement in time allocation – we have guaranteed access
to the Russian 6m BTA (Bolshoi Telescope)
WP10 Optical observations of “Giant Radio Pulses” of the crab nebula, and analysis of data
Start March 2008
Duration 6 months
Responsible PI, Co-I 2 (AS), Co-I 3 (MND)
In this WP we will do the demonstration observations – highly significant in themselves – on a
large telescope. Negotiations will be conducted during the whole project with the responsible teams
on several large telescopes – in particular the 11m Southern Africa Large Telescope (SALT) is a
particularly suitable telescope, and the Director and project scientists have a particular interest in
High Time Resolution Astrophysics.
WP11 Other applications of the optimised DOAP
Start March 2008
Duration 18 months Responsible PI, Co-I, 1 (JCD)
When the final design and construction of the optical module DOAP is completed, the PI and Co-I
1 will investigate other uses – including industrial uses – of this design.
Milestones & Expected Outcomes
March 2007: Final model GaSP Stokes’ polarimeter module, fully calibrated
March 2007: Final mechanical units and assemby of GaSP
September 2007:
Final electronic & software design & construction of GaSP
September 2007:
Berkeley image tube integrated into system
March 2008:
Final GaSP system
September 2008
GaSP system, tested on a large telescope
September 2008
Observations and analysis of the polarimetric properties of optical
pulses from the crab nebula, coincident with “giasnt radio pulses”
The major outcomes of the project will be
1. a unique instrument, built to a professional standard and therefore able to attract
time on large telescopes, capable of investigating a series of new problems in high
time resolution astrophysics
2. a unique design for a high speed, photon-efficint Stokes’ polarimeterfor use in optical
science
3. observations of the Stokes’ vector forthe optical counterparts of “giant radio pulses”
in the crab nebula
What are the recent accomplishments of the PI which suggest that she/he can
successfully address the problem?
This project will be a collaboration between three groups in NUI-Galway, namely;
1. the Applied Imaging Research Group in the Physics Department (Redfern),
2. the SFI Applied Optics Group in the Physics Department (Dainty & Devaney), and
3. the Astrophysics and Scientific Computing Group and the National Centre for High
End Computing (Shearer),
The responsible personnel have a record of successfully collaborating for more than 10 years
For a successful conclusion to the project, it is essential that:
1. A novel instrument should be constructed to a professional standard – acceptable to
the Observatories for equipment to be connected to, and to make a time allocation for
use upon, their expensive, delicate, and over-subscribed telescopes.
2. “Time Allocation Committees” on various large telescopes be convinced to allocate
time to this project, both for the science, and to demonstrate the potential of novel
instrumentation.
Between us we have the necessary experience to do this, and an established track record of
achieving competitive time allocation on large telescopes. We pioneered the use of photon
counting devices for high spatial and temporal resolution astronomical observations on many
large telescopes, including the 4.2m Herschel Telescope in La Palma, the 3.6m ESO and 3.5m
New Technology Telescopes in La Silla, and the 6m Bolshoi Telescope in Russia. Notable
successes include the identification of several optical pulsars, including the first extra-galactic
optical pulsar (in LMC). We discovered pulsed emission from the Gamma-Ray pulsar
Geminga, and enhanced optical emission coincident with giant radio pulses from the Crab
pulsar.
Professor Redfern's group have experience in building astronomical instruments notably the TRIFFID camera used for our pioneering work in high time resolution
observations, and other sorts of instruments using optical photon counting devices - such as
the NucleoFluor detector
(Enterprise Ireland award IF/2002/335, and references in the CV). We have worked on the
development of photon counting devices for astronomy & bio-medical instrumentation.
Professor Redfern is a work package deputy leader (in the instrumentation WP) for the
FP6 project (which is a Pan-Europe Consortium) on technical aspects of a future European
Extremely Large Telescope - he will have particular responsibility for investigating an
instrument for High Time Resolution Astronomy.
Professor Dainty's laboratory has expertise in the conceptual and practical design and
construction of optical instrumentation in many relevant areas, including adaptive optics in
the eye, and Stokes' ellipsometers, in the eye and elsewhere. We have completed a design
study for a suitable Division of Amplitude Polarimeter and will construct the optical core
units of GaSP in this laboratory. An issue of particular difficulty in any polarimeter where
high precision is required is calibration. Professor Dainty’s group have experience in this area
which will be invaluable to the project.
Subsequent to the pre-proposal Dr Nicholas Devaney has been appointed as Lecturer
in Applied Optics in NUI-Galway and we have added him as Co-I to the project. He brings
the knowledge and experience of building optical equipment at the highest level, for large
telescopes, to the project. He has been responsible for the concept, design, and building of the
€7M adaptive optics package for GRANTECAN – the 10.6m Spanish telescope nearing
completion in La Palma. Since we intend that our new instrument will be used on various
large telescopes, which demand a professional level of design and construction before they
can be considered as “guest instruments”, Dr Devaney’s professional expertise adds
considerably to our skills base.
Dr Shearer's group have experience in using the TRIFFID camera and in modelling
pulsar emission mechanisms - essential to completion of this project. Subsequent to the preproposal Dr Shearer has been appointed by SFI as the Director of the High End Computing
Centre. This greatly adds to his ability to develop the necessary data analysis and modelling
facilities needed for the successful use of the proposed instrument.
What is the value of this research to the people of Ireland?
There are several aspects of this project that will benefit Ireland;
1. GaSP is unique in the world, in that it will be a photon-efficient, high-speed imaging
polarimeter. It will find use in bio-medical science wherever the combination of low
light level and high speed is required, which is important for potential applications
such as, (1) in performing ellipsometry of the retina and transparent media in the eye,
and (2) in determining the properties of the cellular medium through fluorescence which have never been attempted to our knowledge.
2. In the past year, the investigator team has been approached by a company based in the
UK to explore the potential for our current research on polarimetry/ellipsometry to be
applied to the sorting of food. At present, many foods (rice, all pulses, vegetables,
fruit) are examined using machine vision systems largely based on colour.
Polarisation offers a new dimension in which to inspect foodstuffs and we confidently
expect that GaSP, together with our existing projects and expertise, will result in an
application of polarisation signature in foodstuff inspection.
3. The development of advanced astronomical instrumentation will bring several benefits
to Ireland. It will place us in a strong position to win contracts from the European
Southern Observatory (ESO) if Ireland joins – as is currently being considered.
Industry will benefit, being well placed as a result to win contracts, such as from ESO.
4. The benefit of the promotion of astronomy and instrumentation to Irish science cannot
be over-emphasised. Astronomical and space topics (for example, the recent
successful landing of the Huyghens probe on Titan) serve to encourage young people
to choose a career in science. The growth of astronomy at undergraduate level over the
past five years has been one of the recent success stories in third level education in
Ireland. Each year 20 excellent undergraduate students are attracted into studying
physics & astronomy in NUI-Galway. These are very much core physics degrees, and
their graduates are physicists. The number of physics students in Ireland has more than
doubled as a result as a result of initiatives in physics/astronomy education. This is
greatly to the benefit of Irish education and industry.
5. Finally, because of the international nature of astronomy and astronomical
instrumentation, this project will open up international links, enabling Irish students to
gain experience abroad and return to Ireland with the benefit of this experience. The
postgrad and postdoc will have excellent employment prospects because there has
never been as much activity in building astronomical instruments worldwide, and
consequently an acute shortage of skilled personnel.
Budget Justification (max 1 page)
We are aware that the project budget exceeds the guidelines by about 30%, but can justify
this on the basis that we are proposing an instrument which has to be built to a professional
standard if it to be competitive on the World stage and to achieve access to large telescopes.
The instrument we are intending to build will open up a new area in High Time Resolution
Astrophysics and will be significant for years to come.
The work involved is large. In order to achieve it we have assembled a skilled
collaborative team (of PI & Co-Is) and also need to employ researchers at both a junior and
senior level. The junior post (postgrad) is to be employed for the whole of the grant, and will
be involved also in the scientific observations at the end. The postdoc is to be employed for 2
years only, and will have responsibility, under the supervision of the project team for the
engineering of the project.
There is a substantial piece of equipment to be built to a professional standard, so that
by comparison with simpler projects, other costs are, of necessity, relatively high also, and
these are justified as follows.
Equipment
The main equipment item is the GaAs imaging camera from Berkeley – this
breaks down as follows:
1. GaAs image tube from Burle Industries
€20,000 including licence
2. NIM fast amplifier units
€9,000
3. NIM time to digital converters
€9,000
4. PCI interface card
€2000
5. Cooler
€4,000
6. EHT set, software control
€2,000
7. NIM rack or equivalent
€2,000
8. contingency for $ variation
€2,000
TOTAL
€50,000
Three computers are needed, one for the lab instrument, later to be used to control GaSP, one
for analysis of the data by the postgrad, and one data storage, equipped with large disk drives,
memory etc. Computers are relatively cheap items
€5,000
Materials & consumables
1. mechanical & electronic materials and components
€10,000 total
2. optical components, includes lenses, polarising components (except the special prism),
static and motorised kinematic mounts needed for calibration.€10,000
3. special prism, budgetary quote from ICOS
€10,000
Travel
1. Observing costs are high, but realistic in our experience of more than 15 years. We
will need 3 persons, and freight costs are very high. The total equipment to be shipped
including test equipment often exceeds 250 kg. Observing cost will be very high if we
succeed in getting time on the South African or one of the Hawaii telescopes.
€20,000
2. Conferences are essential for the education and future career of the Pgrad and Postdoc.
Also essential to establish contacts for the future use of the instrument and to advance
Irish science.
€9,000
Mechanical Construction
This will cover the costs of computer aided manufacture of only the essential, core, items,
which must be manufactured to extremely high standards, by professional toolmaking
companies.
€10,000
CVs of Principle Investigator & Co-Investigators (max 2 pages each)
PI
Professor Michael Redfern B.Sc., Ph.D., M.I.E.E., C.Eng.
Ph.D.
University of Bristol: Research Associate
University College Galway: Statutory Lecturer
NUI-Galway: Personal Professor
1968
1968-1981
1981-1997
1997-present
Redfern has worked in building and using astronomical, and other optical instrumentation for
many years. In Galway he has developed the techniques of image sharpening and instruments
for high time resolution astrophysics. This has led to the discovery of optical pulsations from
a number of pulsars, including the first extra-galactic optical pulsar, and optical pulsations
from the enigmatic X-Ray (but not radio) pulsar “Geminga”. Recently the Galway group
(Redfern, Shearer, and associates) discovered that the association of “giant radio pulses” from
the crab pulsar with significantly larger optical pulsations also – understanding this
association will lead to deeper understanding of the electrodynamics of pulsars. This
important discovery provides part of the rationale for wishing to build the high speed Stokes’
photo-polarimeter which is the subject of this application.
Redfern’s optical researches have also included the development of instrumentation
for bio-physics, detector development, and development of a virtual archive of Irish incised
stones (by laser scanning & modelling).
Redfern was responsible for the introduction of the “Physics & Astronomy” degree to
NUI-Galway, and developed most of the course work and facilties. This was the first ab initio
astronomy degree in the Irish Republic. This has proved to be an important example – similar
degrees are now available in virtually every other university physics department in Ireland. As
a consequence recruitment of physics/astronomy students has increased to be more than 50%
of physics students entering 3rd level. This is greatly to the benefit of Irish education and
training.
Redfern is a signatory, on behalf of NUI-Galway of the Euro50 Consortium agreement
(which covers the development of a 50 m optical telescope). He is a deputy work package
leader for the important instrumentation package of the European ELT FP6 Consortium. He
has been the coordinator of a TMR Training Network in High Resolution Astronomy, and a
work package leader for the TMR Network “Laser Guidestars for 10m Telescopes”
Redfern is a member of the Institution of Electrical Engineers and a Chartered Engineer. He
has been a member of the “National Committee for Astronomy & Space Research” since
1984, and was the Chair of that Committee for six years from 1998 to 2004. He is now the
Secretary of the successor “Royal Irish Academy Committee for Astronomy & Space
Research”
Number of refereed publications to date
60
Number of graduate students supervised to date
Masters
Ph.D.
Postdocs
9
17
7
Number of Research Grants to Date:
20
Value of Grants to date:
>1.4M€
5 Relevant Publications
"Measuring the absolute height and profile of the mesospheric sodium layer
using a continuous wave laser", Butler, D. J.; Davies, R. I.; Redfern, R. M.; Ageorges, N.;
Fews, H.,A&A, 403, 775-785, 2003
"Enhanced Optical Emission During Crab Giant Radio Pulses", Shearer, A.; Stappers, B.;
Connor, P. O'; Strom, A. Golden R.; Redfern, M.; Ryan, O, Science, 301, 493-495, 2003
"Short timescale variability of the mesospheric sodium layer", O'Sullivan, C.; Redfern, R. M.;
Ageorges, N.; Holstenberg, H.-C.; Hackenberg, W.; Ott, T.; Rabien, S.; Davies, R.; Eckart,
A., Experimental Astronomy, v. 10, Issue 1, p. 147-156 (2000).
"Absolute Tilt from a Laser Guide Star: A First Experiment", Esposito, S.; Ragazzoni, R.;
Riccardi, A.; O'Sullivan, C.; Ageorges, N.; Redfern, M.; Davies, R., Experimental
Astronomy, v. 10, Issue 1, p. 135-145 (2000).
"Towards integrated single photon counting arrays", J. C. Jackson, D. Phelan, A. P. Morrison,
M. Redfern and A. Mathewson, Optical Engineering, 42 #1, 112-118, 2003
5 Relevant Research Grants
Enterprise Ireland RIF Programme
"NucleoFluor- Development of a fluorescent analyser for the rapid detection of infectious
pathogens"
2 years €187,185
Enterprise Ireland Basic Research Programme
"Development of the Next Generation TRIFFID Camera for Astronomy & Biophysics"
2 years £85,000
EU Training & Mobility of Researchers Programme "Laser Guidestars for 10m-Class
Telescopes"
3 years £150,000
HEA Funding (PRTLI) Round 3
"Grid enabled computational physics of natural phenomena: Atmospheric modelling"
3 years €110,000
HEA Funding (PRTLI) Round 3 "Virtual archive of incised stone monuments"
3 years €160,000
Co-I 1
Professor J Christopher Dainty M.Sc., Ph.D., F.Inst.P
Professor Dainty's research interests are in optical imaging, scattering and propagation. In
these areas he has published books: 'Scattering in Volumes and Surfaces' (1989, co-edited
with M Nieto-Vesperinas), 'Laser Speckle and Related Phenomena' (1975, 2nd Ed. 1984,
editor) and 'Image Science' (1974) which he co-authored with Rodney Shaw. From 1974-78,
he was a Lecturer in Physics at Queen Elizabeth College of the University of London.
Professor Dainty joined the Institute of Optics at the University of Rochester 1978 and the
faculty of the Department of Physics and Astronomy in July 1982. He became Pilkington
Professor of Applied Optics at Imperial College in January 1984 and was SERC Senior
Research Fellow for the period October 1987 to September 1992. From October 2001 to
September 2002 he was a PPARC Senior Research Fellow. In October 2002, Professor
Dainty started a five-year appointment as Science Foundation Ireland Professor of
Experimental Physics at The National University of Ireland, Galway. He is simultaneously
on extended leave from Imperial College.
Professor Dainty has been active in teaching optics and physics throughout his career, at the
undergraduate and postgraduate levels and in continuing education. He has supervised 41
PhD Theses and currently has 10 PhD students.
He is the 1984 recipient of the International Commission of Optics Prize, the 1993 Thomas
Young Medal and Prize (IoP), the 2003 C E K Mees Medal and Prize (OSA) and the Optics
and Photonics Division Prize 2004 (IoP). He is also a Fellow of The Optical Society of
America, SPIE and The Institute of Physics (UK). From 1983 to 1985 he was elected to the
Board of Directors of the Optical Society of America: 1987–1990 he was elected SecretaryGeneral of the ICO, President for the term 1990–1993 and was Past-President for 1993 to
1996: and 1994 to 1996 he was elected to the Board of SPIE. Prof Dainty served on the
Council of the UK Institute of Physics (1996 – 1999) and is currently past-President of the
European Optical Society. He is a Director at Large of the OSA for the period 2003-2005.
ACADEMIC RECORD
1965 - 1968:
The Polytechnic of Central London.
1968:
The Polytechnic Diploma in Photographic Technology First Class.
1968-1973:
Applied Optics Section, Physics Department, Imperial College,
University of London.
1969:
MSc in Applied Optics, with Distinction.
1972:
PhD in Physics.
PREVIOUS EMPLOYMENT
1971-1973:
Post-doctoral research assistant at Imperial College.
1974-1978:
Lecturer in Physics at Queen Elizabeth College, University of London
(tenured 1976).
1978-1983:
Associate Professor of Optics, The Institute of Optics, The University
of Rochester.
1982-1983:
Associate Professor of Physics and Astronomy, The University of
Rochester.
1984 - present
Pilkington Professor of Applied Optics, The Blackett Laboratory,
Imperial College, London. (on leave-of-absence from October 2002
1987 - 1992
SERC Senior Research Fellow.
2001 – 2002
PPARC Senior Research Fellow
2002 – present
Science Foundation Ireland Professor of Experimental Physics at The
National University of Ireland, Galway (on extended leave from
Imperial College).
THESES SUPERVISED: 41 PhD students, 2 Mphil.
CURRENT RESEARCH STUDENTS: 10
RESEARCH PUBLICATIONS
5 books edited or co-authored
≈120 papers in peer-reviewed journals
≈180 conference presentations
11 book chapters
Recent Relevant Publications:
R A Johnston, J C Dainty, F Reavell and M Bernhardt, ‘Horizontal SCIDAR Cn2(z) estimation’,
Applied Optics 42 3451-3459 (2003)
R W Wilson, N J Wooder, F Rigal and J C Dainty, ‘Estimation of anisoplanatism in adaptive optics by
generalised SCIDAR profiling’, Mon Not R Astr Soc 339 491-494 (2003)
L Diaz-Santana, C Torti, I Munro, P Gasson and J C Dainty, ' The benefit of higher closed–loop
bandwidths in ocular adaptive optics', Optics Express 11, 2597-2605 (2003)
A Dubra, C Paterson∗ and J C Dainty, 'Wavefront reconstruction from shear phase maps using the
discrete Fourier transform' Applied Optics 43, 1108-1113 (2004)
T Shirai and J C Dainty, 'Adaptive optics as a spatial coherence modifier', Optical Review, 11 1-3
(2004)
A Dubra, C Paterson and J C Dainty, ‘Study of the tear film topography dynamics using a lateral
shearing interferometer, Opt Express 12 6278-6288 (2004)
Prof Dainty’s peer-reviewed papers can be downloaded from:
http://optics.nuigalway.ie/chrispub.html.
HONOURS and AWARDS
Fellow of the Optical Society of America.
Fellow of the Society of Photo-Optical Instrumentation Engineers (SPIE).
Fellow of The Institute of Physics (UK)
1984 International commission for Optics Prize
1993 Thomas Young Medal and Prize (UK Institute of Physics)
2003 C E K Mees Medal and Prize (Optical Socieity of America)
2004 Optics and Photonics Division Prize (IoP)
GRANTS and CONTRACTS
Numerous. At Imperial College, >50 major grants in period 1984 to 2002. Current SFI Fellow
Award, €6.2 over five years.
Recent ones include:
Wellcome Trust, “Retinal imaging in neonatal infants, UK£449K, 6/00- 5/05
HEFCE, “AO Laboaratory”, UK£598K (equipment only)
HP Labs. “Smart Optics”, UK£91K, 11/01 –9/05
EU-RTN Programme. “SHARP-EYE”, €240,000 to NUIG, 10/02 – 9/06
SFI, “Advanced Imaging”, €6.2M, 10/02 – 9/07
Co-I 2
Dr Andrew Shearer, BSc, MSc, PhD, M Inst P, C Phys
Present Position: Lecturer in IT, National University of Ireland, Galway Computing (on
leave of absence): Director of the National Centre for High-End Computing
Shearer’s astronomical research has concentrated upon developing the tools - instrumental,
observational, and theoretical - to understand the high-energy emission from pulsars. This work
has resulted in the first optical observations from two pulsars (Geminga and PSR0656+14), the
first observation of an optical enhancement during giant radio pulse events and the determination
- through modelling and observation – of the height in the magnetosphere of the optical emission
in the crab pulsar. The modelling and data analysis has required the extensive use of both highperformance computers and emerging grid technologies. High-time resolution observations
require the use of extensive disk storage and significant computation power for their reduction.
The Astrophysics and Scientific Computing Group in NUI-Galway has developed this expertise
over the past ten years.
Recent Grants
1999 HEA(£80k)
2000
2002
2003
2004
High-Performance Computing and Ultra-Sound
Imaging
HEA (£1.2M)
High Performance Computer for BMES
Enterprise Ireland (28k)
Establishing Grid Ireland
Enterprise Ireland (100k)
Medical Imaging
HEA (PRTLI) (250k) Marine Science Data Mining and Visualisation
HEA (PRTLI) (€2.0M)
Grid-Enabled Computational Physics of Natural
Phenomena
IRCSET(187k)
Observations of Neutron Stars and Magnetars
SFI (€1.52M)
Investigator Award Grid Computing WebCom-G
EI Grant (13k)
Grid-Ireland
SFI(€2.6M)
National Centre for High-End Computing
Membership of Societies etc. – Institute of Physics, IEEE, ACM, Royal Astronomical Society,
International Astronomical Union, Irish Pattern Recognition and Classification Society, SPIE
August 1996-present
National University of Ireland, Galway,
Lecturer in Information Technology and College Radiological Protection Officer
1992 - 1996
University College Galway, Contract Lecturer in Physics
1991 - 1992
University College Galway, Post-Doctoral Research Fellow,
Physics
1985 – 1991
Senior systems designer : ITP Computer Software
1980 - 1984/5
Research Assistant/Associate Bristol University, Physics
Department
1975 - 1980
Research Assistant University of Durham, Physics Department
Membership of other organisations
1995+ IAEA Panel of Experts
1995-1997
Secretary of Astronomical Science Group of Ireland
1997-present
Royal Irish Academy National Committee for Astronomy
1997-present
National representative IAU Commission 46
2003
National Committee of Teaching of Physics
1999-present
1999-2001
2002
2002
2002
INTAS panel of experts grant assessor (Astrophysics &, Medical Imaging)
Assessor for Enterprise Ireland Basic Research Grant Scheme (Maths and
Comp Science panel), Enterprise Ireland Post-doc researchers, Ireland
International Collaboration Grants
Chair Western Regional Science Council
Chair Physics on Stage 2
National Delegate to COST 283 –
Over the past 6 years I had grants totalling over €5M in areas ranging from Astrophysics, Image
Processing, High Performance Computing and Grids.
5 recent relevant refereed papers
FAVOR (FAst Variability Optical Registration) - two-telescope complex for detection
and investigation of short optical transients, Karpov, S., et al , Astronomische
Nachrichten, 325, 677, (2004)
TRIFFID observations of the cores of the three globular clusters M15, M92 and NGC
6712, Tuairisg, S. ´ O., Butler, R. F., Shearer, A., Redfern, R. M., Butler, D., and
Penny, A. , Monthly Notices of the Royal Astronomical Society, 345, 960, (2003)
Enhanced Optical Emission During Crab Giant Radio Pulses, Shearer, A., Stappers,
B., O’Connor, P., Golden, A., Strom, R., Redfern, M., and Ryan, O. , Science, 301,
493, (2003)
Detection of new optical counterpart candidates to PSR B1951+32 with HST/WFPC2,
Butler, R. F., Golden, A., and Shearer, A. , Astronomy and Astrophysics, 395, 845,
(2002)
Implications of the Optical Observations of Isolated Neutron Stars, Shearer, A. and
Golden, A. , Astrophysical Journal, 547, 967, (2001)
Co-I 3
Dr. Nicholas Devaney
Ph.D.
Royal Greenwich Observatory: Research Associate
Observatoire de Meudon,Paris: Research Assocate
Instituto de Astrofísica de Canarias: Support Astronomer
Instituto de Astrofísica de Canarias: Adaptive Optics manager
National University of Ireland, Galway
1989
1989-1991
1992-1993
1993-1995
1995-2005
2005
Dr Devaney was a graduate of the Experimental Physics Department, University College
Galway, where he was awarded the Joseph Larmor Prize for the highest marks in
physical/mathematical science. He completed his Ph.D. in high resolution imaging in Galway,
including work in the Dublin Institute for Advanced Studies, and Instituto de Astrofisica de
Canarias.
After graduation Dr Devaney worked in high resolution imaging in Cambridge (RGO)
and Paris (Meudon) before moving back to Instituto de Astrofísica de Canarias in Tenerife as
support astronomer. He joined the Grantecan project (10.6m Telescope) in 1995 and has been
responsible for the development and design of the important adaptive optics package for that
telescope.
Dr Devaney was appointed as lecturer in applied optics in NUI-Galway in 2005
Number of publications to date
5 most Relevant Publications
30
1. Femenía, B., Devaney, N., 2003, “Optimization with numerical simulations of the
conjugate altitudes of deformable mirrors in an MCAO system”, Astron. Astrophys., 404,
1165-1176
2. Schumacher, A, Devaney, N, Montoya, L, 2002,“Phasing Segmented mirrors: a
modification of the Keck narrow band technique and its application to ELTs”, Applied
Optics, 41, 1297-1307
3. Bello, C.D., Devaney, N., Castro, J., 2000,”The effect of Piston Errors on the Image
Quality of Segmented mirror telescopes”,ReV. Mex. Astron. Astrophys., 36, 57-66
4. Devaney, M.N., Thiébaut, E., Foy, R., Blazit, A., Bonneau, D., Bouvier, J., de Batz, B,
Thom, Ch., 1995,“The H envoronment of T Tauri resolved by speckle interferometry”,
Astron. Astrophys., 300, 181
5. Devaney, M.N., 1992, “Photometric techniques for close binary and multiple systems”,
Astron. Astrophys., 257, 835
Number of Research Grants to Date:
1
Value of Grants to date:
€ 185K
EU Training & Mobility of Researchers Programme "Adaptive Optics for Extremely Large
Telescopes"
4 years €185,000
Adaptive Optics system for the Gran Telescopio Canarias (Received funding from Spanish
ministry of Education and Science based on my conceptual design)
5 years
€9.5 M
Number of graduate students supervised to date
Masters
1
Ph.D.
1
Postdocs
1