Florin Garoi

Compressive THz Imaging and Hadamard Spectroscopy

for Space Applications

THz Imaging

Programme for Research-Development-Innovation for Space Technology and Advanced Research - STAR

Romanian Space Week , 12-16 May 2014, Bucharest, Romania

Coordinating organization

National Institute for Laser, Plasma and Radiation Physics (INFLPR)409 Atomistilor Street, PO Box MG-36, 077125 Magurele, Ilfov, Romania

Project managerFlorin GaroiINFLPRTel/Fax: +40 21 4574467E-mail: florin.garoi@inflpr.roWeb: http://ila.inflpr.ro

Partner organization

University Politehnica of Bucharest – Research Center for Spatial Information (CEO Space Tech)1-3 Iuliu Maniu Bd, Bucharest, Romania

Partner team leaderDaniela ColtucCEO Space TechTel: +40 21 4024873E-mail: daniela.coltuc@upb.roWeb: http://www.cespacetech.pub.ro

Partners

Short description of the project spectroscopy and imaging at THz wavelength range (0.1 – 30 THz); Hadamard spectroscopy Compressive sensing (CS) imaging

Project goal Experimental model of Hadamard spectrometer and CS imaging system in THz domain, for Space

Applications

The project

* with gray are already completed activities

Phase Activities Partner Deadline

IState of the art in THz imaging and Hadamard spectroscopy

1.State of the art in compressive sensing (CS) and Hadamard spectrocospy2.Compressive sensing and Hadamard spectroscopy basics3.Financial and Quality Management

INFLPRUPB

Dec 15, 2012

IIConcept of THz image spectrometer and simulation of imaging and spectroscopy

1.THz image spectrometer as and-to-and system2.Modeling and simulation of imaging and spectroscopy functions3.Financial and Quality Management4.Reporting and dissemination

INFLPRUPB June 30,

2013

IIIExperimental model of THz image spectrometer

1.Design and implementation of the THz data acquisition and DMD2.Characterization of the components in the experimental setup3.Integration of the parts and testing of electrical components of the experimental setup4.Statistical analysis of the measured THz signals and elaboration of appropriate algorithms for CS5.Financial and Quality Management6.Reporting and dissemination

INFLPRUPB Dec 15,

2013

IVFunctions development for THz image spectrometer

1.Definition of the CS and spectroscopy specifications2.Design and implementation of the CS and spectroscopy3.Integration of CS and spectroscopy in the experimental model4.Financial and Quality Management5.Reporting and dissemination

INFLPRUPB Dec 15,

2014

VTHz image spectrometer validation and evaluation

1.Laboratory simulator for ESA applications of interest in THz domain2.Study regarding development of technical perspectives3.Financial and Quality Management4.Reporting and dissemination

INFLPRUPB Nov 18,

2015

Work plan of the project

Characterization of the components in the experimental setupExperimental model v1.0:- FIR 100 laser (Edinburgh Instruments); l = 118.83 mm, 133.1 mm, and 163 mm- Mirrors- Dispersive component:

a) reflective blaze diffraction gratingb) transmission diffraction grating (wire or machine cut)c) prism

- Digital Micromirror Device (DMD)- DetectorSoftware:- LabView- CS

Implementation status

Laser- CO2 section: 80 lines between 9.1μm and 10.9μm

50W on the strongest lines- CO2 laser output is coupled into the FIR laser via two

steering mirrors and a ZnSe focusing lens- FIR section:

118.83mm (150mW), 133.1mm (1mW), and 163mm (36mW)

- Installation and training

Grating cross-section

- Reflective blaze diffraction grating:Brass (CNC EUROMOD-P), coated with 50nm layer of gold (Varian RF magnetron sputtering)Dimensions: 20mm × 20mm × 5mmGrating pitch: 120 mm - not feasible

300 mm - in the making

Optical components- Off-axis parabolic mirrors:

f = 250mm (Laser Beam Products, UK)- Lenses:

f = 50mm, 100mm, 200mm (Tydex, Russia)

Cross-section of the blaze grating

Implementation status

Blaze wavelength as a function of the incidence angle.

- Wire transmission diffraction grating:Brass frame and nickel wireDimensions: 50mm × 50mm × 10mmGrating active area: 40mm × 40mmWire diameter: 200mmGrating pitch: 400mm

- Polyethylene prisms:Prism angle: 60-, 50- and 40-

Implementation status

Wavelength as a function ofdiffraction angle (first diffraction order)

Deviation d versus angle of incidence a Measured with Tera View systems, TPS Spectra 3000

Implementation status- Digital Micromirror Device, DAQ and Detector:

Projection of masks and acquisition - integrated in LabView Tested in visible range of the spectrum

- Testing with various random matrices generation for CSFind a sensing matrix through random methods that accurately reproduces a given image and scaling for a finer resolution with more samples or larger sensors coverage; for example Low Density Parity Check (LDPC) matrices

Project start TRL 1 – Basic principles observed and reported Lowest level of technology readiness. Scientific research begins to be translated into applied research and development

PresentTRL 2 – Technology concept and/or application formulatedOnce basic principles are observed, practical applications can be invented and R&D started. Applications are speculative and may be unproven

TRL 3 – Analytical and experimental critical function and/or characteristic proof-of-conceptActive research and development is initiated, including analytical/laboratory studies to validate predictions regarding the technology

Intended to be achieved

TRL 4 – Component and/or breadboard validation in laboratory environmentBasic technological components are integrated to establish that they will work together

Physical Fourier encoding of optical data

Preliminary tests of the dispersive elements, in visible and THz range

Results

Experimental setup

Decoded images

Initial objects

ResultsOne Pixel Camera for THz Image AcquisitionDesign and Tests of Camera Software

EXPERIMENTS: Test images (numerical): Cameraman and Lena

Tested Sensing matrices: Binary Random Binary Sparse LDPC (Low Density Parity Code) Tested Transforms: Discrete Cosine Transform Wavelet Transform TV (Total Variation)

FOUND SOLUTION: LDPC with TV

Rate-Distortion curves for TV

Rate-Distortion curves for LDPC

ACQUISITION PRINCIPLE: Compressive Sensing (CS)

SCOPE: finding the appropriate couple Sensing Matrix – Transform for CS Algorithm

SOFTWARE: CS Toolbox at http://w3.impa.br/~aschulz/CS/CS-codes.zip L1 Magic at http://www.cms.caltech.edu/

EXPERIMENTAL RESULTS

METHOD: couple evaluation by Rate-Distortion curve

Project’s contribution to the goal of the STAR Programme (how the project contributes to the increasing of the capacity for organizations involved to participate in ESA Programmes)

The project addresses Basic Technology Research Programme (TRP), one of ESA’s activities regarding technology and research → may facilitate strong and long-term relations between Romanian entities and ESA.

Context and contribution to ESA Programmes (please specify how the project activities can contributes to present and future ESA programmes)

We hope that our research on THz imaging with CS and Hadamard spectroscopy contribute to the development of new instruments required for the current and long-term ESA science directorate programme.

Project contribution to STAR

Programme

Publications and Conferences Rate-Distortion Performance of Compressive Sensing in One Pixel Camera, Mihai Petrovici, Daniela

Coltuc, Mihai Datcu, and Vasile Tiberius, Submitted to IEEE Signal processing Letters Physical Fourier encoding and compacting of optical data, Petre Catalin Logofatu, Florin Garoi, Victor

Damian and Cristian Udrea, Submitted to Optical Engineering Terahertz range complex refractive index determinations for liquids using ATR, Adrian Dobroiu and Petre

Catalin Logofatu, Submitted to Optical Engineering Introduction to Compressive Sampling and applications in THz Imaging, Daniela Coltuc, Invited paper to

ATOM-N 2014 Conference (Constanta, August 21-24, 2014) Dispersive elements for THz domain, V. Damian, Mihaela Bojan, G. D. Chioibasu, F. Garoi, P. C. Logofatu,

L. Mihai, C. Udrea, I. Urzica, T. Vasile, and C. Viespe, will be presented at INDLAS 2014 Conference (Bran , May 19-23, 2014)

Synthetic aperture and scarsity analysis methods for THz imaging, Mihai-Alexandru Petrovici, will be presented at the European Conference on Computer Vision (Zurich, September 6-12, 2014)

L1 minimization applied to the simple case of a sparse signal consisting in a sum of sinusoids, Petre Catalin Logofatu, will be presented at ATOM-N Conference (Constanta, August 21-24, 2014)

Technical Notes within the consortium(available upon request)

For up-to-date info, please visit our webpage:http://ila.inflpr.ro/THzImaging

Dissemination

Conclusions

Conclusions

All tasks and activities completed as scheduledMost important results: Installation and training for the THz laser Simulation of the experimental setup v1.0 Characterization of some of the components Definition of the CS matrices and algorithms for data processing