Transcript Time-resolved optical imaging through turbid media using a fast gated CCD camera

Time-resolved optical imaging
through turbid media using a fast
data acquisition system based on a
gated CCD camera
Cosimo D’Andrea, Daniela Comelli, Antonio Pifferi, Alessandro
Torricelli, Gianluca Valentini and Rinaldo Cubeddu
INFM-Dipartimento di Fisica and IFN-CNR, Politecnico di Milano Piazza Leonardo da Vinci
Milan, Italy
Rui Li
12-01-05
Outline
Introduction
Materials and Methods
Results and Discussion
Optical Imaging
Tumour detection (e.g. breast tumours)
Noninvasive
Reconstruct reduced scattering
(μ’s=μs(1 − g) g = <cosθ> )
and absorption coefficients (μa)
Optical Tomography
Forward Model
μ’s
μa
Inverse Problem
Clinical Trial
Development of a time-domain
optical mammograph and first
in vivo applications
Gr¨osenick D, Wabnitz H, Rinneberg H, Moesta
K T and Schlag P M
1999 Appl. Opt. 38 2927–43
Dual-wavelength time-resolved
optical mammograph for
clinical studies
Cubeddu R, Giambattistelli E, Pifferi A, Taroni P
and Torricelli A
2001 Photon migration, optical coherence
tomography, and microscopy Proc. SPIE vol 4431
Problem
Spatial resolution for
clinical applications:
1mm
A huge data set
required
Long measurement
time
Outline
Introduction
Materials and Methods
Results and Discussion
Experimental Set-up
Mode-locked Argon Laser
(CR-18, Coherent, CA)
λ:514nm, pulse width:
120ps, repetition rate:
80Mhz
Intensifier tube
(HRI, Kentech, UK)
gated from 200ps to 1ns,
Repetition rate up to 100MHz
CCD camera
(PCO, GmbH, Germany)
Dynamic range: 12 bit
Experimental Set-up
INT
CCD
8×8 binning forms
an effective pixel
Totally 160×128 effective pixels
Image size: 10cm
Each effective pixel: 0.8×0.8mm2
Experimental Set-up
HRI (High Rate Imager)
Time!
120 images,
delayed by 50ps
Each image100ms
Totally less than
30s!
Random Walk Theory
μ’s
μa
2D
3D
Random Walk Theory
In an Infinite homogeneous slab
Outline
Introduction
Materials and Methods
Fast Gated Intensified CCD
Random Walk Theory
Results and Discussion
Homogeneous sample
Intralipid® (IL)
(Pharmacia, Italy)
and black India ink
(Rotring, Germany)
contained in a
rectangular glass tank
(15×15×5 cm3)
Image area: 6cm
μ’s=11cm-1
μa=0.05cm-1
Measurement of different IL and ink
concentration
Inhomogeneous Sample
The inclusions:
solid cylinders
(1 cm↕ = 1 cmø)
made of agar, IL and
ink
Scattering inclusion
FWHM
45mm
30mm
15mm
Time-gated Imaging
I inc
I hom
A- inclusion
hardly detected!
Outline
Introduction
Materials and Methods
Fast Gated Intensified CCD
Random Walk Theory
Results and Discussion
Scattering inclusions
Absorbing inclusions
Conlusions
 12 bit CCD image 6cm diameter acquisition time
of only 30s.
 Experimental data were analyzed with
theoretical function for a homogeneous medium
or using a temporal gate technique.
 Localize inclusions and discriminate between
absorption or scattering abnormalities.
A diagnostic device for rapidly
detecting inclusions.
Later Work
 Localization and quantification of fluorescent inclusions embedded in
a turbid medium
Cosimo D’Andrea, Lorenzo Spinelli, Daniela Comelli, Gianluca Valentiniand
Rinaldo Cubeddu
Phys. Med. Biol. 50 (2005) 2313–2327
Critique
 Spatial resolution
1mm?
Scattering inclusion
 Reconstruction
μ’s, μa, dimension?
 Absorbing inclusion
 Later work?
FWHM
45mm
30mm
15mm
Thank you!
107-Gb/s optical ETDM transmitter for 100G
Ethernet transport
Peter J. Winzer, Greg Raybon, and Marcus Duelk
Bell Labs, Lucent Technologies
Presented at ECOC (European Conference and Exhibition on Optical Communication)
Presented by Mitul Patel
Outline


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Introduction
System Overview
Transmitter setup
Receiver setup
Results
Conclusions
Introduction


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Increased use of Ethernet for data delivery in
WAN (wide-area networks) topologies
10G Ethernet has gained much popularity
100G Ethernet is the next logical step (10x
increase typically)
Introduction, con’t

Historical development of Ethernet Speeds
Introduction, con’t
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In this paper the first 107-Gb/s optical ETDM
(electrical time-division multiplexed)
transmitter is presented. This would be
suitable for transport of 100G Ethernet
Why 107-Gb/s?
–
100-Gb/s data rate + 7% error correction
overhead
System Overview
Both a transmitter and receiver had to be constructed to fully test
the system
Transmitter Setup
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Generate two identical 53.5 Gb/s PRBS
(pseudo-random bit sequence) into 100-Gb/s
2:1 multiplexer
1 PRBS delayed by 1.6 ns
Transmitter, con’t
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Eye diagrams before and after multiplexing
Transmitter, con’t

Multiplexer output sent to a MZM (Mach-Zehnder
modulator) which modulated a 1550-nm laser.
Transmitter, con’t
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MZM (biased at minimum transmission) used
to generate a 107 Gb/s optical duobinary
modulation.
–
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Duobinary modulation – method to transmit R
bits/s using less than R/2 Hz of bandwidth
http://www.inphi-corp.com/products/whitepapers/DuobinaryModulationForOpticalSystems.pdf
Transmitter, con’t
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Pictures show scope
diagram and optical
spectrum of 107-Gb/s
signal.
Receiver Setup
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Signal first passed through an optical
attenuator and an Erbium-doped fiber
amplifier (EDFM) to set the optical signal-tonoise ratio (OSNR)
Then passed through a 2-nm optical
bandpass filter
Receiver, con’t
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No 107-Gb/s electronic 1:2 demultiplexer was
available so they used a 1:2 optical time-division
demultiplexer (OTDM) implemented using another
MZM (driven at 26.75 GHz, biased at minimum
transmission).
Signal converted down to 53.5 Gb/s
Results
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After the signal was received it was sent to a
bit error rate tester (BERT) for analysis
Tested both a short (27 – 1) bit pattern and a
larger (231 - 1) pattern
Both 53.5 Gb/s signals were measured
separately by tuning the phase of the drive
signal to the demuxing MZM
Results, con’t
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Short patterns are
almost error-free while
the larger patterns level
off around 10-6
They attributed this to
the MZM’s non-ideal
filter characteristics
causing amplitude
ripple
Results, con’t

However, using the 7% overhead for error
correction allows for correcting a 10-3 BER
down to 10-16.
Results, con’t
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Finally the chromatic dispersion tolerance was measured.
107 Gb/s signal was sent over various lengths of single-mode fiber
Conclusion

Successfully able to demonstrate the first
optical ETDM 107 Gb/s transmitter suitable
for use in 100G Ethernet.