Terahertz Spectral Range

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1 Inhalt 1. Einleitung 2. Wechselwirkung Licht-Materie 3. Bilanzgleichungen 4. Kontinuierlicher Betrieb 5. Relaxationsoszillationen 6. Güteschaltung 7. Modenkopplung 8. Laserresonatoren 9. Eigenschaften von Laserlicht 9.1 Kohärenz 9.2 Photonenstatistik 10.Lasertypen 10.1 Festkörperlaser 10.2 Flüssikgkeitslaser 10.3 Gaslaser 11. Anwendungen 11.1 Erweiterung des Frequenzbereiches Terahertz-Strahlung Nichtlineare optische Frequenzkonversion

2 Terahertz Spectral Range LaserphysikWS09/10 2

3 Terahertz: Research and Applications Technology Development LaserphysikWS09/10 3

4 THz Systems for Time Domain Spectroscopy From laboratory systems to industrial applications Lab system portable Real time analysis modular, portable und flexible LaserphysikWS09/10 4

5 Fiber Coupled THz System Dispersion pre compensation in a grating stretcher Max. 20 m fiber length Directly fiber coupled heads LaserphysikWS09/10 5

6 Spektroskopie Eigenschaften von THz-Strahlung Technologie und Messtechnik Anwendungsbeispiele Möglichkeiten und Grenzen LaserphysikWS09/10 6

7 Asynchroneous Sampling with Fiber Lasers Principle: LaserphysikWS09/10 7

8 Blick in die Zukunft - Highlights der Forschung Sicherheitstechnologie Fernerkennung von Sprengstoffen LaserphysikWS09/10 8

9 Terahertz: Research and Applications Industrial applications: spectroscopy, imaging and security LaserphysikWS09/10 9

10 Terahertz Technology for Industrial Inspection Quality control Material sciences Inspection of surfaces Layer thickness measurements Flaw detection in a volume Measuring of moisture in a volume Packed or unpacked objects Analysis of charge carrier mobility and concentration in semiconductors Pharmaceuticals, chemicals, food Security Medicine / Biology Degree of purity and analysis of blends Changes of conformation, isomeric molecules Identification of drugs, explosives and explosive related compounds Diagnostics of cancer, skin as well as DNA LaserphysikWS09/10 10

11 Application of Photonic THz Radiation 100 % Intensity R % T % transmission & reflection surface, absorption, foreign bodies, voids,. Time structure tomography layer thickness, boundaries,... Amplitude & Phase spectroscopy identification, 0,51,01,52,02,53,03,54,0 Frequenz [THz] 0,51,01,52,02,53,03,54,0 content, concentration,... LaserphysikWS09/10 11

12 Imaging of hidden objects 20 mm LaserphysikWS09/10 12

13 Changing dynamic range 20 mm LaserphysikWS09/10 13

14 Hyperspectral Imaging Complete information in each single pixel: spectrum, time delay, amplitude,phase Variation of center frequency LaserphysikWS09/10 14

15 Display modes Display modes (signal based): Display modes (time based): A. maximum signal B. minimum signal C. amplitude D. total energy E. FFT maximum F. absorption a. maximum position b. minimum position c. zero position d. pre-zero position e. max-to-min distance f. max (min) width g. FFT max position LaserphysikWS09/10 15

16 Terahertz Technology for Industrial Inspection Quality control Material sciences Inspection of surfaces Layer thickness measurements Flaw detection in a volume Measuring of moisture in a volume Packed or unpacked objects Analysis of charge carrier mobility and concentration in semiconductors Pharmaceuticals, chemicals, food Security Medicine / Biology Degree of purity and analysis of blends Changes of conformation, isomeric molecules Identification of drugs, explosives and explosive related compounds Diagnostics of cancer, skin as well as DNA LaserphysikWS09/10 16

17 Security Applications all explosives have characteristic absorptions between 0.5 and 10 THz Transmission 0,5 THz 2 THz 1 THz Charact. Absorption Spectral window for the detection of explosives Intensity Absorption Coefficient [1/mm] RDX TATP compb PETN HMX ,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 Frequency [THz] 2.84 LaserphysikWS09/10 17

18 Stand off Detection of Explosives Absorptionskoeff. [cm -1 ] Lactose 0,5 1,0 1,5 2,0 2,5 3,0 Frequenz [THz] physical problems: Reflection spectra transmission reflection reflection through cloth differentiation Lactose as dummy Measurement of spectra in reflection and transmission through clothing and different dielectric materials Measurements over large distances reflection/transmission [rel. u.] 0,0 0,5 1,0 1,5 2,0 frequency [THz]? Principle component analysis for reflection spectra LaserphysikWS09/10 18

19 Water Vapor Absorption Hinweis: Luftfeuchte auf 1 m THz-Strecke hochgerechnet LaserphysikWS09/10 19

20 Water Vapor Absorption Stand-off measurements over distances more than 20 m are with currently available THz sources and detectors almost impossible. LaserphysikWS09/10 20

21 Reflection/transmission Spectra Tartaric acid Salycilic acid Aminobenzoic acid Transmission Reflection LaserphysikWS09/10 21

22 Principal Component Analysis in Reflection Measurements in reflection Classification in dry and humid air and through clothing LaserphysikWS09/10 22

23 Principal Component Analysis in Reflection Spectrum Analysis Classification: 7 substances in reflection in dry and humid air and through clothing Measurements under almost real conditions Identification uncertainty < 5% LaserphysikWS09/10 23

24 Spectroscopic Applications From gases to solid state 3 Absorption z/2[a. u.] 2 1 Gas / Vapor CO NO Liquids 0 0,6 0,8 1,0 1,2 Frequency [THz] Solid State LaserphysikWS09/10 24

25 THz Time Domain Spectroscopy (TDS) (a) (b) Electric Field [a.u.] Reference Sample FFT Reference Sample E-3 1E-4 Amplitude Spectrum [a.u.] Intramolecular (c) Time Delay (d) Frequency [THz] Abs.coeff. [cm -1 ] Refractive Index Intermolecular Frequency [THz] Frequency [THz] 1.55 LaserphysikWS09/10 25

26 Spectroscopy Real-time gas analysis Detection limits: - CO: 20 ppm m - NO: 20 ppm m - HCl: 300 ppm m -NH 3 : 300 ppm m Time domain 1.3 Hz rep. rate Measurements in strongly scattering media Frequency domain Absorption spectrum HCl Measurements through plastic pipes tm-technisches Messen 68,388 (2001) LaserphysikWS09/10 26

27 Spectroscopy Quantitative analysis LaserphysikWS09/10 27

28 Spectroscopy Polymorphism C.J. Strachan et al., Chem. Phys. Lett 390, 20 (2004), J. A. Zeitler et al., J. Pharm. Sci. 95, 2486 (2006) LaserphysikWS09/10 28

29 Spectroscopy Amorpheous vs. Cristalline THz as fingerprintregion for biomolecules Absorption coefficient [a. u.] cristalline amorpheous Glucose Frequency [THz] LaserphysikWS09/10 29

30 Layer Thickness Measurement Scotch tape in reflection LaserphysikWS09/10 30

$1 mm index of refraction has to be known False color image$

31 Layer Thickness Measurement Scotch tape in transmission THz in <50 μm plastic holder THz out sensitive to thickness changes accuracy +/- 2 µm minimum thickness: < 10 µm focus diameter approx. 1 mm index of refraction has to be known False color image LaserphysikWS09/10 31

32 Layer Thickness Measurements Coated metal plates Layer thickness app. 100 µm LaserphysikWS09/10 32

33 Coating on CFRP LaserphysikWS09/10 33

34 Liquid on PE Foil Shrinking during drying process is detectable! Measurements every 15 minutes LaserphysikWS09/10 34

Takeshi Yasui, Takashi Yasuda, Ken-ichi Sawanaka, and Tsutomu Araki

35 Real-time 2D THz Tomography of Moving Paint Film Sample: half-paint film on metal plate Continuous moving of a paint sample (moving speed = 5 mm/s) Takeshi Yasui, Takashi Yasuda, Ken-ichi Sawanaka, and Tsutomu Araki Graduate School of Engineering Science, Osaka University, Japan LaserphysikWS09/10 35

± 21 µm @ 1~4 mm Takeshi Yasui, Takashi Yasuda, Ken-ichi Sawanaka, and Tsutomu

36 THz Tomographic Movie of Moving half-paint Film 5 10 frame/sec =20º, d=5mm Unpainted area Position(mm) Boundary Blurry edge 0 0 Time(ps) 6 Painted area 162 ± 21 1~4 mm Takeshi Yasui, Takashi Yasuda, Ken-ichi Sawanaka, and Tsutomu Araki Graduate School of Engineering Science, Osaka University, Japan LaserphysikWS09/10 36

37 THz Imaging in Reflection Corrosion under paint layers LaserphysikWS09/10 37

Applications of Terahertz Radiation (T-ray) Yao-Chang Lee, National Synchrotron Research Radiation Center

Applications of Terahertz Radiation (T-ray) Yao-Chang Lee, yclee@nsrrc.org.tw National Synchrotron Research Radiation Center Outline Terahertz radiation (THz) or T-ray The Interaction between T-ray and