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Laser Applications R&D at FraunhoferInstitute for Laser Technology
Jens Gottmann, Claudia Hartmann, Alexander Horn,Leonid Moiseev, Lena Trippe
Fraunhofer Institut fr Lasertechnik &
Lehrstuhl fr Lasertechnik
der RWTH-AachenSteinbachstrasse 15
52074 Aachen
Germany
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Outline
The Fraunhofer Institute for Laser Technology
Related Results & Planned Experiments at JLAB FEL
Micro-ablation with tailored pulse trains Drilling with s-laser radiation
PLD
Conclusion
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Tailored Optical Energy
Manufacturing
- Processes
- System technology
Microelectronics (EUV)
Life science
- Biophotonics
- Biocompatible
Materials
Atomic and molecular
Lasers
Power/ Energy
Quality
- space (focusability)
- time (pulse durationand formation)
- spectral (wavelength,
Laser types)
1 m
20 cm
150 nm
Application
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Vertical Structure: Car body welding with a high power DPSSL
High-powerdiode-laser chips andpackaging Lifetime
Systems design:high efficiency and
beam quality
Dr.Ing. H.c. F.Porsche AG
Weldingprocess andmaterialsscience
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Organisation of Fraunhofer-ILT and of LLT RWTH Aachen University
Plasma and X-Ray
LLTDr. E. W. Kreutz
Dr. J. Gottmann
Prof. Dr. R. PopraweVice Director
Administration
ILTDr. P. Loosen
B. Grossmann
Beam Sources Laser Applications
Integrated Optics
Beam Sources
Metrology andSurface Analysis
Laser ComponentsDr. K. Boucke
Solid State/Diode LasersD. Hoffmann
MetrologyDr. R. Noll
Plasma TechnologyDr. W. Neff
CLT PlymouthDr. S. Heinemann
CLFA ParisDr. W. Knapp
Joining and CuttingDr. D. Petring
Surface TechnologyDr. K. Wissenbach
Micro TechnologyDr. A. Gillner
System IntegrationDr. S. Kaierle
Surface Technology
Micro StructuringThin Film Technology
System Integration
Modelling and Simulation Dr. W. Schulz
Marketing andCommunication
A. Bauer
Quality ManagementDr. A. DrenkerM. Talkenberg
IT-ManagementDr. B. Weikl
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Planned Experiments atJLAB FEL
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Motivation
Industry needs e.g. drillings and microstructures
more reproducible
faster production
higher quality (e.g. melt-free)
Development
of anapplication-
adapted lasersystem
Solution new laser system
high-power
high repetition rate
ultra-short pulse duration
Challenge plasma formation
interaction of laser radiation with plasma
Use a FEL
Variation of
repetition rate
wave length
pulse duration
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Related Results & planned Experiments
Micro-ablation with tailored pulse trains
Drilling with s-laser radiation
PLD
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HOCHSCHULEAACHEN
U:\PC_WNDWS\VORLAGEN\LLT_1.pot
Micro-ablation with tailored pulse trains
Claudia Hartmann
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Micro-ablation with laser radiation
aim
expansion of process limits during micro-ablation of metal (1064 nm)
less melt on the surface high ablation rates
use of tailored pulse trains
interdepartmental cooperation of corecompetence teams of ILT/LLT
process know-how laser techniques
system technology modelling and simulation
state of the art
micro-ablation with femtosecond -microsecond pulses
materials: metals and ceramics 2.5 dimensional structures 355 nm - 1064 nm (depending on
material)
Used Laser for Project at ILT/LLT
pulse duration 15 ns to 50 ns burst energy 2 mJ
pulses per burst 4 pulse distance 0,1 s to 3 s
b)a) c)
Ablated structures in:a) Al2O3b) sapphirec) steel
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Process know-how / laser techniques
Parameter:
l = 10 HzEB = 2 mJl = 14 ns to 50 nst= 0,1 s to 2s
purpose
high ablation rate high ablation quality
(melt reduction,small Ra, ...)
ideal ablation parameters
variation of parameters
burst and pulse energy number of pulses per burst pulse duration
pulse distance repetition rate
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
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double pulse
EB = 2 x 1 mJt = 2 s
triple pulseEB = 3 x 0,66 mJ
t1 = t2= 2 s
=250ns =5s =15s
single pulseE= 2 m J
1 mm
tdel tdel tdel
Process analysis by high speed photography
Pulse bursts:
Results
Plasma of pulse bursts strips of the surface Magnification factor of the plasma volume:
10 for double pulse, 15 for triple pulse Plasma emission of pulse bursts have larger
emission times
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
High-speed Microstructuring of Copper, Aluminum and Steel
verage Power at the Sample Surface, Pt 26 W
Maximum Average Pulse Peak Intensity, IP 92 MW/cm
2
M2- Value (focused beam) 1.6
Repetition Rate, f 4.1 MHzWavelength at Workpiece 532 nmPulse Duration, p 13 ps
OscillatorAmplifier
Frequency
Conversion BeamDump
Focusing Optics
and Scanners
Sample
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Results
Top view Top view Cross-section view
Copper
Steel
Aluminium
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Ablation Experiments at FEL
A: ablation experiments in steel 1.4301 (=304) and C70
A1: single pulse ablation
different pulse delays (=rep. Rate.) variation of: - pulse energy
- pulse overlap- wavelength
A2: ablation with pulse bursts
different delays: pulse delay during one burst burst delay
variation of: - number of pulses per burst (1,2,5, )- burst energy- pulse overlap- wavelength
High-speed-photography of plasma dynamics
metallography, SEM and optical microscopy
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RHEINISCH-
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HOCHSCHULEAACHEN
U:\PC_WNDWS\VORLAGEN\LLT_1.pot
Drilling with s-laser radiation
Lena Trippe
/
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Drilling at LLT / ILT with laser radiation
state of the art: single pulse and
trepan drilling with s-laser-radiation stainless steel, nickel-based
superalloy cylindrical hole geometry resolidified melt layers 15m aspect ratio 20 : 1 time / hole < 20s (trepan drilling)
Nd:YAG Slab Laser
pulse duration: 100-500smax. pulse power: 2kWfocal diameter: 40mM < 2
aim: expansion of process limits during
percussion drilling (high speed drilling) metals and ceramics material thickness 5mm aspect ratio > 100 : 1
time / hole
1sinterdepartmentalcooperation of corecompetence teams:
process know-howlaser techniques system technology modelling and
simulation
process limits
understandingof processes
process diagnostic
processmonitoring
processcontrol
modelling,analysis
simulation,numerical
approximation
1mm
60m
single pulse drilling(X5CrNi18-10)
4mm
=60, 200m
trepan drilling
(CMSX-4)
Ad t ti f i t
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Adaptation of processing parameters
< 500nm ablation depth/pulse < 1-5mm< 3mJ pulse energy < 0.1-50J< 1.5mm material thickness < 10mm
quality
complete
removalof material
geometry
...
productivity
ablation rate
...
vapourisation
helicaldrilling
melting
percussiondrilling
10s100ns
?
pulseduration
P k h / l t h i
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Process know-how / laser techniques
variation of parameters: pulse energy pulse duration temporal pulse shape focal position repetition rate ...
development of hole geometryduring one pulse
single pulse drilling
Nd:YAG-Slablaserpulse energy: 180mJpulse duration: 200smaterial: X5CrNi18-10
purposes: reduction of recast layers and
closures cylindrical geometry of hole
=> parameters for percussiondrilling
cross-section of single pulse drillings
Process analysis by high speed photography
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Process analysis by high speed photography
plasma
(spikes)
melt / closure atthe hole entrance
pulse shape
200m
-200 0 200 400 600 800,0
0,1
0,2
0,3
0,4
0,5
0,6
intensity[a.u.]
t ime [s]
single pulse 500s, 500mJ, dt=20shole diameter
decreasing intensity of
laser radiation
Modeling and simulation
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Modeling and simulation
-30 0 30 60 90 120 150 180 210 2400
100
200
300
400
500
600
700
800
900
holedepth[m]
t ime [s]
experiment
simulation
-30 0 30 60 90 120 150 180 210 240-1
01
2
3
4
5
6
7
8
9
intensity[a.u.]
t ime [s]
time scales of physical processes: beginning of melting
and vapourisation time until meltflow
becomes stationary
geometrical scales: hole depth depth where
resolidification occurs hole diameter
Drilling experiments at FEL
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Drilling experiments at FEL
vapour
plasmaabsorption
laserradiation
Analysis of physical processes
absorption of laser radiation (vapour,plasma) at different wavelengths
plasma formation and absorption of laserradiation at different pulse numbers anddelays
development of hole geometrydepending on pulse numbers
find timescales and geometrical scales incomparison to drilling with s-pulses
melt
material
Drilling experiments at FEL
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Drilling experiments at FEL
B: drilling experiments (metals (X5CrNi18 10, CMSX-4, Al, Cu),
ceramics (Si3N4, AlN))B1: single burst drilling
variation of: - number of pulses (1,2,5,10,20,50,100)- different pulse delays
- pulse energy- wavelength
B2: multi-burst drilling variation of: - number of burst (1,2,5,10,20,50,100)
- number of pulses/burst (1,2,5,10)- different pulse and/or burst delays- pulse energy- wavelength
High-speed-photography of plasma dynamics
metallography, SEM and optical microscopy
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RHEINISCH-
WESTFLISCHETECHNISCHE
HOCHSCHULEAACHEN
U:\PC_WNDWS\VORLAGEN\LLT_1.pot
Pulsed Laser Deposition
Leonid Moiseev
25Pulsed Laser Deposition
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Pulsed Laser Deposition
Anti reflective coating (ZrO2, Al2O3) onarrays of cylindrical lenses of PMMA
Ferroelectric thin films (BaTiO3, PZT)
BaTiO3
Pt
Si
cladding
electro-opticQ-switch
Er:BaTiO3
laser mediumEr:BaTiO3
substrate
Q-switch waveguide laser by PLDand microstructuring
BaTiO3 thin films on Si/Pt
26Pulsed Laser Deposition
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Pulsed Laser Deposition
target
processing gas
substrate
Laser radiation
plasma/vapour
Plasma expansion during PLD
27Spectroscopy on laser-induced plasmas
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LEHRSTUHL FR LASERTECHNIK
RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
p py p
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29Heat conduction in the target and absorption by the plasma
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RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
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0 1 2 3 40
20
40
60
80
100
BaTiO3
Heat conduction in target
absorption by plasma
Pa
rtitioningo
fopticalen
ergyP[%]
Fluence L[J/cm
2
]
30Kinetic energy of the particles
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RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
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Model: Comparison with plume dynamics by iCCD:
elastic collisions
T
prc
mcE
L
i
ikin
3
2
1
1+=
, [1]
inelastic collisions(macroscopic)
23
2
1
1
+
=
T
prc
mcE
L
i
ikin
elastic inelasticmaterialc1[eV/u] c1[eV/u]
c2/MPg
Al2O3 2,3 0,4 4,1 0,8 6,0 0,5ZrO2 1,2 0,2 1,7 0,3 5,0 0,5BaTiO3 0,9 0,2 1,5 0,3 2,5 0,3
[1] Gottmann et. al.: (E-MRS 1997)Surf. Coat. Technol. 100-101, (1998) p. 415
0 1 2 30
5
10
15
20
Collision kinetic models c2=16 x 10
10K/m
2
inelastic, v0=18 km/s elastic, v
0=15 km/s
ZrO2
O2, m=32
L=3 J/cm2
T=20 C
2 Pa
7 Pa10 Pa
20 Pa
100 Pa
Meanvelocity
[km/s]
Distance from target R [cm]
31Ellipsometry: Refractive index of ZrO2 films
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RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
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2
5 10 30 100
1.2
1.4
1.6
1.8
2.0
2.2
2.4
Zone 3Zone 2Zone 1
k n
dS=3,5cm;
L=3,5J/cm
2
dS=2,7cm;
L=3,5J/cm
2
dS=2,7cm; L=5,0J/cm2
0.00
0.02
0.04
0.06
0.08
0.10
Calculated kinetic energy Zr
[eV]
Absorptio
nindexk(=
633nm)R
efrac
tiveindexn(=633nm)
TS=20 C
L=3.5 J/cm2
The bulk values n=2.2 and k=0
are achieved at =20 - 50 eV
32Deposition Experiments at FEL
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RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
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C: deposition experiments of oxides and fluorides
C1: ablation for plasma diagnostics
optical emission and absorption spectroscopy
variation of: - different pulse delays
- pulse energy- wavelength
C2: pulsed laser deposition with pulse bursts measurement of deposition rate, optical and structural filmproperties and correlation with plasma parameters
variation of: - number of pulses per burst- burst energy- wavelength
33Aim of all planned Experiments & Conclusion
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RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Analysis of physical processes ablation
process efficiency: absorption of laser radiation in vapour/ plasmaat different wavelengths and pulse energies,
kinetic energy of particles: plasma expansion and absorption oflaser radiation using different pulse numbers, delays and energy
correlation of the physical processes with the resultingdeposition/ablation rate and film properties
modelling of the processes using the FEL-parameters
Find out parameters for
the deposition of high quality films at high deposition rates (>1 m/s/cm2) the ablation/drilling with tailored pulse trains to precondition the surroundinggetting melt-free structures
34Aachen and ILT
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RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
AACHEN
Rathaus Dom
Carl der Grosse
Marktplatz
ILT&LLT
35Adaptation of processing parameters
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RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
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fs-pulses:
lower ablation rate high quality
ms-pulses:
high ablation rate lower quality
tpt-project:
high ablation rate high quality
36Modeling and simulation
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RHEINISCH-WESTFLISCHETECHNISCHEHOCHSCHULE
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Model for ablation process:
Following pulses againinteract with the surface
VPB >> VSP, mPB >> mSP drSP/dt< 0, drPB/dt> 0 single pulse: spheric
discoid
pulse burst: discoid spheric
consequence of theprecondition due to the previouspulses