n5.3 – homeland security, medical, pharmaceutical, and non

Applications of THz Radiation APS March Meeting, March 23, 2005

Homeland Security, Medical, Pharmaceutical and Non-destructive

Testing Applications of Terahertz Radiation

Colin Baker

[email protected]

[email protected]

Overview

Introduction to terahertz

Techniques imaging and spectroscopy

Applications of terahertz light

Medical

Non-destructive testing

Pharmaceutical

Security

Conclusions

TeraView The Terahertz Company

Founded April 2001 Cambridge, England

Exclusive focus on terahertz technology and applications 30+ staff

Close relationship with Cavendish Laboratory, Cambridge University

Developed worlds first portable terahertz imager & spectrometer

Focus markets medical imaging, pharmaceuticals, security screening,

non-destructive testing

TeraViews TPI range

What is Terahertz?

Visible Infra-redMilli-metre

Terahertz gap

Ultra-violetX Ray

Micro-wave and

Radio

1019Hz 1018Hz 1017Hz 1016Hz 1015Hz 1014Hz 1013Hz 1012Hz 1011Hz 1010Hz

Terahertz region 300 GHz 10 THz (1 mm 30 micron)

Until recently inaccessible due to lack of sources and detectors

Key properties:Penetrates clothing, leather, paper, plastics, packing materials

Materials identification using characteristic Terahertz spectra

3-D imaging capability

Non-ionizing - no damage to body or cells

Photoconductive THz generation

Vbias GaAs device

90 fs NIR laser pulse Emitted THz pulse

Photoconductive THz detection

IGaAs device

90 fs NIR laser pulse THz pulse

Basics of THz Pulsed Imaging

TPI provides for time of flight analysis, as well as producing spectral information.

A proportion of the incident pulse will be reflected back whenever there is a change in the refractive index.

Reconstruction of the multiple detected pulses permits depth profiling. X-Y raster scanning builds a 3D image.

Non-Destructive Testing 3-D Terahertz Imaging of integrated circuit package

visible images

Terahertz images seeing inside the chip

2 mm deeptop surface 1mm deep

Medical Imaging

Applications

Skin cancer imaging basal cell carcinoma

Surgeons aid tissue typing

Endoscopy prostrate & other cancers

Status

Results very promising

TPI Scan imager in use for clinical research

Probe based systems under development

Patient 9 (TPP 285)

x (mm)y

(mm

)

0

0.20

0.40

0.60

0.80

1.00

Skin Cancer In vivo surface and depth

information

Pharmaceuticals

Applications

Process improvement

Polymorph screening

Tablet inspection

Status

Reflection imaging system

Partnership with Bruker

Range of products available including reflection and transmission spectrometers

0.0 0.5 1.0 1.5 2.0 2.5 3.0

0

1

2

3

4

1.8THz

1.6THz

1.3THz

1THz

abso

rptio

n

frequency / THz0.0 0.5 1.0 1.5 2.0 2.5 3.0

0

1

2

3

4

5

1.2THz

abso

rptio

n

frequency / THz

Crystallineform 1

Crystallineform 2

TPI spectra 1000

25 50 75 100 125 150100

101

102

103

104

105

106

107

1080.8 1.5 2.3 3.0 3.8 4.5

sign

al /

arb.

uni

ts

wavenumber / cm-1

reference sample

water vapourlines

crystallinephonon bands

frequency / THz

0 5 10 15 20 25 30 35-2000

0

2000

4000

6000

8000

10000

THz

elec

tric

field

/ ar

b. u

nits

optical delay / ps

reference sample

FFT

Terahertz Pulse Profile

20 40 60 800

1

2

3

4

5

6

7

0.6 1.2 1.8 2.4 Form I Form II Form III Form IV Form V

Frequency/THz

Abs

orba

nce

(dec

adic

)

Wavenumber/cm-1400mg, 13mm diameter tablet20% sulphathiazole in PE

Samples provided by Terry Threlfall, U. of Southampton

Using terahertz pulsed imaging as a tool to investigate coating integrities

single incidentTHz pulse

coatedtablet

multiple return pulses

Reflected THz pulses probe coating structure

Non-destructive mapping of coating thickness in pharmaceutical tablets

Terahertz pulses reflect from each coating layer

Time of flight and scanning over surface allows mapping of coating layers

Security

Checkpoint people screening for hidden weapons & explosives

Stand-off detection of explosives

Baggage screening for explosives

Screening for biological & chemical agents

white powder detection

Terahertz & Security:Key Issues

SignaturesDo threat materials have characteristic signatures?

Are they distinct from confusion materials?

BarriersWill terahertz penetrate clothing and other barriers?

ReflectionCan signatures be detected in reflection?

DistanceCan we see (at least) 10 metres?

Source power/ detector sensitivity

Atmospheric absorption

SystemsCan we design practical systems?

What sources and architectures should we use?

Terahertz spectra of explosives

0 1 2 3 4

HMX

PETN

RDX

PE4

TNT

Semtex

Abs

orpt

ion

(off

set f

or c

larit

y)

Frequency (THz)

Terahertz transmission spectra

Energetic compounds and explosives

All show characteristic features at terahertz frequencies

Note:

Most features above 0.5 THz

Barrier material absorption limits practical range to 3THz

Kemp et. al., Proc SPIE 5070, 44 (2003)

Semtex-H reference measurementsAbsorption and reflection spectra of Semtex calculated

from measurements in transmission spectrometer

TeraView data November 2004

0.50 0.75 1.00 1.25 1.50 1.75 2.000.00

0.02

0.04

0.06

0.08

0.10

0.12

0

10

20

30

40

50

60 Reflectance Absorption

R

efle

ctan

ce

Frequency/THz

Abs

orpt

ion/

cm-1

Measurements of potential confusion materials

TeraView has measured a library of terahertz spectra of common materials - developed with support of UK Department of Trade & Industry

Also includes many pharmaceutical compounds

No significant confusion found between explosives and harmless materials

0 1 2 3 40

1

2

3

4

5

(+3.0)

Abs

orba

nce

(dec

adic

)

Frequency (THz)

co-codamol

milkchocolate

Tribe et. al., Proc SPIE 5354, 168 (2004)

0.0 0.5 1.0 1.5 2.0 2.5 3.00

1

2

3

4

Cocoa Washing Powder Aspirin Milk Chocolate Flour Ibuprofen Blusher Paracetamol Soap Sugar Vitamins

Abs

orba

nce

(dec

adic

)

Frequency/THz

Clothing & Barrier Materials

All clothing materials are partially transparent

Absorption increases with frequency

Limits useful frequency range to 2-3 THz

0.0 0.5 1.0 1.5 2.0 2.5 3.00

1

2

3

4 Cotton Silk Wool Leather Nylon Polyester Polyester/cotton

Abs

orba

nce

(dec

adic

)

Frequency/THz

Tribe et. al., Proc SPIE 5354, 168 (2004)

Detecting metals, non-metals and explosives hidden in clothing

subjects arm

hidden object

cotton 4 layers

wool 2 layers

terahertz beam

Detecting metals, non-metals and explosives hidden in clothing

image

metal scalpel blade ceramic plastic sheet explosive

depth profile

Terahertz images of objects (approx 1cm across) hidden under 2 layers of wool and 4 layers of shirt material

Kemp et al. Proc SPIE 5070, 2003

Terahertz detection of sheet explosive underneath clothing

Image of 1cm square piece of SX2 sheet explosive against skin, hidden under two layers of woollen jumper and four layers of cotton shirt material

TeraView data March 2003

Ongoing development programmes

Objective: move from proof-of-principle to prototype

and then to fieldablesystem

Two projects:

People Screening Hand Wand

Stand-off Explosives Detection

People Screening Wand

Terahertz wand to detect metal & non-metallic weapons and explosives

Marketing partnership with Smiths Detection

Initial prototype under construction

Detection techniques and algorithms being developed

Smiths Detection

Terahertz reflection spectrum from Hand Wand raw data

TeraView data January 2005



Programme funded by UK Home Office PSDB, with US participation

Laboratory prototypes under construction

Initial target 1m

Source & detector development to achieve larger stand-off distances

Development of detection techniques and algorithms

Experimental system

Femtosecondpulsed laser

Beamsplitter

Delay stage

Detector

Emitter

Target

Experimental System in Operation

0 1 2 3 410-810-710-610-510-410-310-210-1100

Pow

er

Frequency/THz

Response of stand-off THz system

Target 1m

Path Length over 2m

Water windows correspond to spectral features of explosives

0 1 2 3

Frequency (THz)

Water absorption

RDX

Semtex

Semtex-H Stand-off spectrum at 1 metre

0.50 0.75 1.00 1.25 1.50 1.75 2.000.02

0.04

0.06

0.08

Semtex-H System Purged Semtex-H Calculated

Ref

lect

ance

Frequency/THz

THz spectrum of Semtex-H (composed of RDX and PETN) measured data at stand off distance of 1 m

System purged with nitrogen gas to remove water vapour.

Data collected in 70 ms, with a spectral range of 0.3 2 THz


Semtex-H spectrum with water vapourTHz spectrum of Semtex-H measured data at stand off distance of

1m in atmospheric air

Note effect of water vapour absorption lines


0.50 0.75 1.00 1.25 1.50 1.75 2.000.02

0.04

0.06

0.08

Semtex-H at 1m (no purging) Semtex-H Calculated

Ref

lect

ance

Frequency/THz

Semtex-H spectrum corrected for water vapour effects

Reflection spectrum at stand off distance of 1m, data collected in 70ms

Water vapour absorption lines removed by data processing algorithm.

0.50 0.75 1.00 1.25 1.50 1.75 2.000.02

0.04

0.06

0.08

Semtex-H at 1m (no purging), after data processing

Calculated

Ref

lect

ance

Frequency/THz


Semtex and SX-2 spectra

0.50 0.75 1.00 1.25 1.50 1.75 2.000.02

0.04

0.06

0.08 SX-2 Semtex-H Calculated Semtex-H

Ref

lect

ance

Frequency/THz

Spectra of two different RDX based explosives showing same distinctive features

Data collected at 1m stand-off through normal atmosphere with 70ms integration time water vapour lines removed


Conclusion

0.50 0.75 1.00 1.25 1.50 1.75 2.000.04

0.06

0.08

Semtex-H at 1m (no purging), after data processing

Calculated

Ref

lect

ance

Frequency/THz

Terahertz is very promising technology for many applications

Proof-of-principle confirmed with measurements and data

Technology now moving forward to commercialisation

Acknowledgements

Dr Bill Tribe

Dr Tom Lo

Dr Mike Kemp

Dr Philip Taday

Michael Withers

Michael Evans

Dr Bryan Cole

Dr Ian Bradley

Dr Simon Chandler

Homeland Security, Medical, Pharmaceutical and Non-destructive Testing Applications of Terahertz RadiationOverviewTeraView The Terahertz CompanyWhat is Terahertz?Non-Destructive Testing 3-D Terahertz Imaging of integrated circuit packageNon-destructive mapping of coating thickness in pharmaceutical tabletsSecurityTerahertz & Security:Key IssuesTerahertz spectra of explosivesMeasurements of potential confusion materialsClothing & Barrier MaterialsDetecting metals, non-metals and explosives hidden in clothingDetecting metals, non-metals and explosives hidden in clothingTerahertz detection of sheet explosive underneath clothingOngoing development programmesPeople Screening WandTerahertz reflection spectrum from Hand Wand raw dataStand-off Explosives DetectionExperimental systemExperimental System in OperationWater windows correspond to spectral features of explosivesSemtex-H Stand-off spectrum at 1 metreSemtex-H spectrum with water vapourSemtex-H spectrum corrected for water vapour effectsSemtex and SX-2 spectraConclusionAcknowledgements

n5.3 – homeland security, medical, pharmaceutical, and non

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