Through A Glass Darkly Goals T ec hnical Approac h · Darkly The Laser Line-Scanner Pro ject Dr....
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* Near-field multiply scattered light Detector FOV Laser Off-axis light, Scattering losses Sunlight * illumination detector scattered into 0.0001 0.001 0.01 0.1 1 10 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Model 10m MCML 10m Model 2m MCML 2m
Transcript of Through A Glass Darkly Goals T ec hnical Approac h · Darkly The Laser Line-Scanner Pro ject Dr....
Through A Glass Darkly
The Laser Line-Scanner Project
Dr. Jonathan Stott (NU), Prof. W. Clem Karl (BU),
Prof. Eric Miller (NU), and Prof. Charles DiMarzio (NU)
Goals
Our goal is to improve the performance of theRaytheon laser line scanner (LLS).
* Near-field multiply scattered light
Detector FOV Laser
Off-axis light,
Scattering losses
Sunlight
*
illumination
detector scattered into
Signi�cance
� Ocean- oor sea mine detection
� Environmental monitoring
� Data inversion and sensor fusion
Technical Approach
Phase One|Model Light Propagation
Physics based signal processing
1. Radiative transport equation (RTE)
(k̂ � ~r)L(~r; k̂) =
��L(~r; k̂) + �
Zd
k̂0
4�f(k̂; k̂0)L(~r; k̂0)
� Very accurate, but diÆcult to solve.
� From RTE, make intuitive assumptions anddevelop model for the propagation of laserlight under the surface of the ocean.
� Model includes the e�ects of sunlight andnear-�eld multiply scattered light.
2. Monte Carlo calculations
� Few simplifying assumptions necessary.
� Potentially accurate, but very slow (preci-sion proportional to number of photons).
3. Validate RTE-based model against Monte Carlo.
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Comparison between our �rst-order model
predictions and Monte Carlo calculations of
the beam spread function.
Phase Two|Imaging
� Want to measure �(~r ), the re ectivity of theocean oor.
� Signal seen at the detector y(~r ) is
y(~r ) =
Z ZK(~r;~r 0)�(~r 0) d2~r 0 + �(~r )
where K(~r;~r 0) is the imaging kernel and �(~r ) isthe noise term.
� Assume translational invariance
� Reconstruct target re ectivity
{ Back-projection
{ Deconvolution
{ Wiener �lter
Synthetic Data
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1|Data−Reconstruction|
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Demonstration of image reconstruction
using noisy synthetic data.
Relation to CenSSIS
� SeaBED: �rst CenSSIS project with proprietaryfunding (Raytheon).
� Fundamental physics used to generate forwardmodel for light propagation.
� Physical model, in turn, improves image recon-struction algorithms of LLS.
� Work between the di�erent sites (NU and BU)coordinated via email/www and through regularface-to-face meetings.
Other Connections
� Work on di�usive wave imaging feeds in tomodeling of near-�eld multiply scattered light.
� Techniques from hyperspectral imaging (e.g.principal component analysis) are relevant for fu-ture work on improving LLS imaging by integra-tion of existing uorescence channels.
Current Status
� Forward model has been developed and is nowbeing validated against experimental data.
� Work on image reconstruction is on-going.
� Project is currently funded through June, 2000.Proposal for continuing funding submitted.
PI Contact Information
Name Charles DiMarzioTitle Principal Research Scientist
Institution Northeastern UniversityAddress FR 235
360 Huntington Ave.Boston, MA 02115
Phone (617) 373-2034Fax (617) 373-8627Email [email protected]
Plans and Project Evolution
Future
2Q 2000and beyond
1Q 2000
3Q and 4Q 1999Forward Model
ImageFormation
AdvancedHardware
LaserSources Configurations
Detector
ImageReconstruction
ClassificationLocalization
DetectionChannelFusion
(Fluorescence)
