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Time-resolved optical imaging through turbid media using a fast data acquisition system based on a 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

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Time-resolved optical imaging through turbid media using a fast data acquisition system based on a gated CCD camera

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  1. 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

  2. Outline • Introduction • Materials and Methods • Results and Discussion

  3. Optical Imaging • Tumour detection (e.g. breast tumours) • Noninvasive • Reconstruct reduced scattering (μ’s=μs(1 − g) g = <cosθ> )and absorption coefficients (μa)

  4. Optical Tomography Forward Model μ’sμa Inverse Problem

  5. 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

  6. Problem • Spatial resolution for clinical applications: 1mm • A huge data set required • Long measurement time

  7. Outline • Introduction • Materials and Methods • Results and Discussion

  8. 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

  9. 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

  10. Experimental Set-up

  11. HRI (High Rate Imager)

  12. Time! • 120 images, delayed by 50ps • Each image100ms • Totally less than30s!

  13. Random Walk Theory μ’sμa 3D 2D

  14. Random Walk Theory In an Infinite homogeneous slab

  15. Outline • Introduction • Materials and MethodsFast Gated Intensified CCDRandom Walk Theory • Results and Discussion

  16. 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

  17. Measurement of different IL and ink concentration

  18. Inhomogeneous Sample The inclusions: solid cylinders (1 cm↕ = 1 cmø) made of agar, IL and ink

  19. Scattering inclusion FWHM 45mm 30mm 15mm

  20. Time-gated Imaging A- inclusion hardly detected!

  21. Outline • Introduction • Materials and MethodsFast Gated Intensified CCDRandom Walk Theory • Results and DiscussionScattering inclusionsAbsorbing inclusions

  22. 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.

  23. Later Work • Localization and quantification of fluorescent inclusions embedded in a turbid mediumCosimo D’Andrea, Lorenzo Spinelli, Daniela Comelli, Gianluca Valentiniand Rinaldo CubedduPhys. Med. Biol. 50 (2005) 2313–2327

  24. Critique • Spatial resolution1mm? • Reconstructionμ’s, μa,dimension? • Absorbing inclusion • Later work?

  25. Thank you!

  26. 107-Gb/s optical ETDM transmitter for 100G Ethernet transportPeter J. Winzer, Greg Raybon, and Marcus DuelkBell Labs, Lucent TechnologiesPresented at ECOC (European Conference and Exhibition on Optical Communication) Presented by Mitul Patel

  27. Outline • Introduction • System Overview • Transmitter setup • Receiver setup • Results • Conclusions

  28. Introduction • 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)

  29. Introduction, con’t • Historical development of Ethernet Speeds

  30. Introduction, con’t • 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

  31. System Overview Both a transmitter and receiver had to be constructed to fully test the system

  32. Transmitter Setup • 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

  33. Transmitter, con’t • Eye diagrams before and after multiplexing

  34. Transmitter, con’t • Multiplexer output sent to a MZM (Mach-Zehnder modulator) which modulated a 1550-nm laser.

  35. Transmitter, con’t • MZM (biased at minimum transmission) used to generate a 107 Gb/s optical duobinary modulation. • 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

  36. Pictures show scope diagram and optical spectrum of 107-Gb/s signal. Transmitter, con’t

  37. Receiver Setup • Signal first passed through an optical attenuator and an Erbium-doped fiber amplifier (EDFM) to set the optical signal-to-noise ratio (OSNR) • Then passed through a 2-nm optical bandpass filter

  38. Receiver, con’t • 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

  39. Results • 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

  40. 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

  41. Results, con’t • However, using the 7% overhead for error correction allows for correcting a 10-3 BER down to 10-16.

  42. Results, con’t • Finally the chromatic dispersion tolerance was measured. • 107 Gb/s signal was sent over various lengths of single-mode fiber

  43. Conclusion • Successfully able to demonstrate the first optical ETDM 107 Gb/s transmitter suitable for use in 100G Ethernet.

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