Transcript Solid State Photon-Counters for High Time Resolution Astrophysics Solid State Photon-Counters for High Time Resolution Astrophysics (HTRA) Giovanni Bonanno, Sergio Billotta, Massimiliano Belluso, M.

Solid State Photon-Counters for High Time Resolution Astrophysics
Solid State Photon-Counters
for
High Time Resolution Astrophysics (HTRA)
Giovanni Bonanno, Sergio Billotta,
Massimiliano Belluso, M. Cristina
Timpanaro, Alessandro Grillo, G.
Occhipinti
INAF Astronomical Observatory of
Catania, Italy
Giampiero Naletto
Department of Information Engineering,
University of Padova, Italy
Tommaso Occhipinti, Enrico Verroi,
Cesare Barbieri
Department of Astronomy, University of
Padova, Italy
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
SCIENTIFIC MOTIVATIONS FOR HTRA
-1-
Current astronomical instrumentation essentially only exploits the
properties of first order coherence of light, usually for imaging (spatial
coherence) or spectroscopy (temporal coherence).
The second order coherence functions (Glauber (1963)), can give
additional information about source emission mechanisms, i.e. thermal
or laser source.
The present main limitation to carry out
this analysis is the size of today’s
telescopes that are not large enough to
collect the very high number of photons
necessary to discriminate the presence
of coherence at the second order
Quantum Photometer
correlation from the poissonian photon
counting statistics.
More details about the possible scientific return of a quantum photometer on an ELT, and on
smaller size telescopes can be found in papers of Dravins et al. (2006); and Barbieri et al.
(2006, 2007).
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
SCIENTIFIC MOTIVATIONS FOR HTRA
Quantum-photometers applied
to ELTs
-2From Andy Shearer, on
behalf of the Opticon
HTRA network
thanks to:
 much higher photon flux
 extremely high timing
accuracy and very long term
stability
Hanbury-Brown–Twiss intensity interferometry
over two or more apertures.
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
OPTICON HTRA Network DETECTORS Req.
from Andy Shearer, Centre for Astronomy
NUI, Galway, Ireland
on behalf of the Opticon HTRA network
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
The Best Solution
for HTRA
A detector system capable
to be sensitive to the single
photon and push the time
tagging capabilities of each
incoming photon toward the
100 ps – 1 ns region,
sustaining up to 1GHz count
rates continuously for hours of
uninterrupted acquisition.
A front-end electronics able
to satisfy these requirements.
IMAGING ARRAY??
A photon counting imaging array detector placed
at the telescope focal plane would have been the
simplest and easiest way to operate, but ……
MCPs + CCD or CMOS
timing resolution (MCP) < 100 ps
few kHz and relatively low
PDE in the visible range.
Fast time tagging not allowed
EMCCD multi-port + fast readout
few kHz Binning mode? More
output? Optimization. Future work.
See C. MacKay, S. Tulloc this meeting.
SIGLE ELEMENT
OR
ARRAY COUPLED TO OPTICS
SDfA 2009, 12-16 October 2009, ESO - Garching
Fast time tagging difficult
SPAD array
extremely good timing accuracy,
can sustain fairly high count rates,
good quantum efficiency and low
dark count.
Fast time tagging OK!
Small sensitive area
and low pixel density  Fill Factor!!!
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Solid State Photon-Counters for High Time Resolution Astrophysics
The Best Solution
for HTRA
Furthermore the choice of a
single element SPAD has two
adverse consequences:
1. finding an optical solution
coping with very small
sensitive areas
2. fixed aperture photometer
without imaging capability,
sets limitations to a very The
baseline
good scientific utilization.
QUANTEYE is
solution
for
a non-imaging
photometer made by a focal
reducer plus a 32x32 lenslet
array 1024 pixel detector.
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
CURRENTLY AVAILABLE MOST PERFORMING DETECTOR
1. Time Accuracy
After a detailed analysis of pro’s and
con’s on presently available technology
(and resources), we decided to adopt
as detector for the first HTRA
applications a single element SPAD,
due to good parameters like:
1. Time tagging accuracy
2. PDE
3. Dynamic range
Time accuracy of the order of 35 ps
SDfA 2009, 12-16 October 2009, ESO - Garching
A pulsed laser system equipped with a multiple
grey filter illuminates a SPAD, at the same
time the trigger from the laser sends the
START to a time-to-amplitude converter (TAC).
When the SPAD detects the photon from the
laser it sends the STOP to the TAC. The TAC is
connected to a PC to build the distribution of
the time intervals between the laser trigger and
the photon detection on the SPAD.
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Solid State Photon-Counters for High Time Resolution Astrophysics
CURRENTLY AVAILABLE MOST PERFORMING DETECTOR
2. Photon Detection Efficiency PDE
From right to left you can find: a Xenon
lamp used as the radiation source, a
wavelength selection system constituted
essentially by a set of filters and a Czerny–
Turner monochromator a beam splitter to
direct the monochromatic radiation towards
an integrating sphere that hosts a NIST
traced reference detector and the SPAD.
PDE approaches 60% at 550 nm
SDfA 2009, 12-16 October 2009, ESO - Garching
The use of an integrating sphere is
crucial because the very small size
of the SPAD with respect to the
optical beam.
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Solid State Photon-Counters for High Time Resolution Astrophysics
CURRENTLY AVAILABLE MOST PERFORMING DETECTOR
3. Dynamic Range and after-pulse
By means of several neutral filters or
changing the aperture of the entrance or exit
slits of the monochromator we can vary the
photon flux intensity coming into the
integrating sphere.
Active Quenching Circuit
AQC
While the measurement of the afterpulse
effects, is achieved by measuring, at
different over-voltages the dark count rate
varying the hold off time by means of the
AQC.
From our measurements
we essentially found the
characteristics
reported
on the manufacturer’s
data sheet:
SDfA 2009, 12-16 October 2009, ESO - Garching
- a dead time of 75 ns after each detected event
- a typical after-pulsing probability around 1%
- a linear count rate up to 2 MHz (NIM output,
timing accurate) or 12 MHz (TTL output, timing
less accurate)
- a dark count rate less than 50 cnts/s
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Solid State Photon-Counters for High Time Resolution Astrophysics
IQUEYE
Schematic view of IQUEYE optical design
A PRECURSOR FOR THE NEXT
GENERATION HTRA
Iqueye, is a conceptually simple fixed
aperture photometer which collects
the light within a FoV of just a few
arcseconds (selectable from 1” to
6”), splits the telescope light beam in
4 equal parts, and focuses each subbeam on an independent SPAD.
Two wheels allow to insert along the
optical path suitable filters and
polarizers. Since there is no imaging
capability, a field camera visualizes
the portion of the sky under
investigation.
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
ACQUISITION AND TIMING SYSTEM OF IQUEYE
The peculiar and
innovative part of
Iqueye is the data
acquisition
system
that,
utilizing
a
rubidium
oscillator
and a GPS receiver,
allows to time tag the
detected
photons
with a final absolute
UTC referenced rms
time accuracy better
than 0.5 ns over one
hour of observation.
IQUEYE at NTT Nasmyth B
ACQUISITION
AND TIMING
SYSTEM
SPAD
DETECTORS
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
MODULAR SYSTEM EASILY EXPANDED
The data acquisition system itself
can be easily expanded to a large
number of pixels by simply
add/replacing VME boards. The
rest will remain the same with
slightly changes in software.
OPTICAL FIBER
BRIDGE 60 Mb/s
16 pixels
128 pixels
Demonstrator for high density
SPAD detector of the HTRA or
HBT II instrument on ELT.
data are long
strings of time
tags
1024 pixels
Can give useful information to
implement FPGA-ASIC
specialized circuits
design SPAD arrays architectures,
that can arrange TDCs directly on
chip by using the CMOS
technology
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
IQUEYE + NTT
MAIN CHARACTERISTICS
System sensitivity
Photon counting
Relative time
accuracy
100 ps (1 h continuous
obs.)
Absolute time
accuracy
500 ps (1 h continuous
obs.)
Dark count rate
< 100 C/s
Maximum count rate
8 MC/s
Dynamic range
> 40 dB
Limiting magnitude
mV =24 (2 h exp. time
S/N=10)
Observations at the NTT
On 14-19 January 2009
PRELIMINARY RESULTS
Crab Nebula
V =16.5
Effective FOV
selectable
3.5, 5.2, or 6.1 arcsec
Operative spectral
range
350 ÷ 925 nm
System total
efficiency
33% (peak @ 550 nm)
18% (average 350 ÷
925 nm
Individual counts with 0.33 ms bin size
Crab Nebula
T bins 0.07 ms
Crab Nebula light curves
obtained with 1 sec of
acquisition
Crab Nebula
More details in A&A G. Naletto et al.: Iqueye, a single
photon counting photometer applied to the ESO NTT
SDfA 2009, 12-16 October 2009, ESO - Garching
T bins 0.6 ms
Great sensitivity !!!
Ability
to resolve with good
statistics the 33 ms single periods
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Solid State Photon-Counters for High Time Resolution Astrophysics
NEAR FUTURE DEVELOPMENTS FOR HTRA --1—
SINGLE PIXEL
 Solid-State photon-counters
 Good quality of the La Silla site
 Performance of NTT
allowed us to obtain
Significant amount
of scientific data
now under analysis
The detectors shown good performances in terms of:
TIME TAGGING ACCURACY
 PDE
 HIGH DYNAMIC RANGE
 MODEST DARK COUNT
 RELIABILITY AND EASY OPERATION
But, we have to quote:
LONG DEAD TIME (preventing to reach a count rate claimed by each SPAD itself)
AFTERPULSING NOT NEGLIGIBLE
see next slide
SINGLE PIXEL SMALL AREA CONFIGURATION
MPD (the SPAD manufacturer) is already working to find the best compromise
between deadtime, timing jitter and afterpulsing.
CAEN (the VMECrate manufacturer) is working on a dedicated TDC board with the
acquisition computer directly inside the VME crate to increase the
communication bandwith.
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
NEAR FUTURE DEVELOPMENTS FOR HTRA --2—
SPAD ARRAY
POLIMI
SINGLE-PHOTON ARRAY
 1024 Single-Photon pixels
SINGLE PIXEL
D.E.I.
F. Zappa
 Up to 100,000 frame/s for
the whole imager
 Pixels work completely in
parallel
ARRAY LAYOUT
32 X 32 pixels
100µm
100µm
PIXEL LAYOUT
 Negligible interframe
dead-time (20 ns)
 Global shutter
 Multiphoton detection
capability
CMOS SPAD (20µm)
INTEGRATED QUENCHING CIRCUIT
GLOBAL SIGNALS
8 BIT COUNTER
INTERNAL MEMORY BUFFER
1 ms
1 ms
100 ms
10 ms
FIRST TESTS
NO AR COATING, NO MICROLENSES
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
NEAR FUTURE DEVELOPMENTS FOR HTRA --3—
SPAD ARRAY
32 x 32 pixels SINGLE-PHOTON ARRAY OPERATING MODE
2nd STEP
COLUMN SELECTOR
COLUMN SELECTOR
Integration time
During this time
detected photons
counted
D.E.I.
F. Zappa
3rd STEP
ROW SELECTOR
ROW SELECTOR
ROW SELECTOR
1st STEP
Stop integration
COLUMN SELECTOR
Array readout
the
are
During this phase the During this phase each
counts are stored in memory contents is
memory
readout
while
the
detected photons are
counted
No sacrifice of multi-photon detection
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
DETECTORS FOR HTRA
Replace the 8-bit
COUNTER with an
8-bit TDC and live
the same memory
buffer and bus
NEXT STEP
Build a 32x32 SPAD
array in epi-technology
with appropriate AQC
boards and use multiple
TDCs VME boards
1024
Pixels
Build a microlenses array and place it on the detector surface to improve the fill factor
Build a fiber’s holder to be placed directly on the detector surface and use a bundle
of fibres to reach the telescope focal plane
Fiber’s
holder
Extreme
Large
Telescope
focal plane
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
Cross-section
of
a
CMOS-SPAD integrated
into one cell
Photon Detection Efficiency
at different over-voltages of
a CMOS-SPAD
0.35 μm high-voltage CMOS technology
SDfA 2009, 12-16 October 2009, ESO - Garching
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Solid State Photon-Counters for High Time Resolution Astrophysics
SUMMARY AND CONCLUSIONS
 HTRA can rely on extremely fast photon counting photometers
utilizing new solid state detectors and appropriate electronics
capable of accurate time tagging better than 1 ns
 These detectors are characterized by a fast time response of 100
ps, a PDE that approaches 60 % in the visible, a very low dark count
rate and a good linearity.
Thank you very much
 Time-resolved measurements have been demonstrated by
for your
Iqueye, a fast photometer
based attention
on these detectors, mounted at the
ESO-NTT focal plane
 HTRA needs for sure two dmensional arrays.
-- Some work have been done to have SINGLE-PHOTON ARRAYS
for very-fast IMAGING.
-- Some other improvements are in progress.
SDfA 2009, 12-16 October 2009, ESO - Garching
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