laser applications r&d at fraunhofer institute for laser technology · 2004-03-18 · laser...
TRANSCRIPT
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
U:\PC_WNDWS\VORLAGEN\LLT_1.pot
Laser Applications R&D at Fraunhofer Institute for Laser Technology
Jens Gottmann, Claudia Hartmann, Alexander Horn, Leonid Moiseev, Lena Trippe
Fraunhofer Institut für Lasertechnik &Lehrstuhl für Lasertechnikder RWTH-AachenSteinbachstrasse 1552074 [email protected]
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Outline
•The Fraunhofer Institute for Laser Technology
•Related Results & Planned Experiments at JLAB FEL
Micro-ablation with tailored pulse trains Drilling with µs-laser radiationPLD
•Conclusion
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Tailored Optical Energy
Manufacturing- Processes- System technology
Microelectronics (EUV)
Life science- Biophotonics- BiocompatibleMaterials
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 FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Vertical Structure: Car body welding with a high power DPSSL
High-power diode-laser chips and packaging Lifetime
Systems design: high efficiency and
beam quality
© Dr.Ing. H.c. F.Porsche AG
Welding process and materials science
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Organisation of Fraunhofer-ILT and of LLT RWTH Aachen University
Plasma and X-Ray
LLTDr. E. W. KreutzDr. J. Gottmann
Prof. Dr. R. PopraweVice Director
Administration
ILTDr. P. LoosenB. Grossmann
Beam Sources Laser Applications
Integrated Optics
Beam Sources
Metrology and Surface 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
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
U:\PC_WNDWS\VORLAGEN\LLT_1.pot
Planned Experiments at JLAB FEL
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Motivation
Industry needs e.g. drillings and microstructures
more reproducible
faster production
higher quality (e.g. melt-free)
Development of an
application-adapted laser
system
⇑Solution new laser system
high-powerhigh repetition rateultra-short pulse duration
Challengeplasma formation interaction of laser radiation with plasma
Use a FEL
Variation of
repetition rate
wave length
pulse duration
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Related Results & planned Experiments
Micro-ablation with tailored pulse trains
Drilling with µs-laser radiation
PLD
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
U:\PC_WNDWS\VORLAGEN\LLT_1.pot
Micro-ablation with tailored pulse trains
Claudia Hartmann
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Micro-ablation with laser radiation
aimexpansion of process limits during micro-ablation of metal (1064 nm)
less melt on the surfacehigh ablation rates
⇒ use of tailored pulse trains
interdepartmental cooperation of core competence teams of ILT/LLT
process know-howlaser techniquessystem technologymodelling and simulation
state of the artmicro-ablation with femtosecond -microsecond pulses
materials: metals and ceramics 2.5 dimensional structures355 nm - 1064 nm (depending onmaterial)
Used Laser for Project at ILT/LLTpulse duration 15 ns to 50 ns burst energy 2 mJpulses per burst ≤ 4pulse distance 0,1 µs to 3 µs
b)a) c)Ablated structures in:a) Al2O3b) sapphirec) steel
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Process know-how / laser techniques
Parameter:νl = 10 HzEB = 2 mJτl = 14 ns to 50 ns∆t = 0,1 µs to 2µs
purposehigh ablation ratehigh ablation quality (melt reduction, small Ra, ...)
→ ideal ablation parameters
variation of parametersburst and pulse energynumber of pulses per burstpulse durationpulse distancerepetition rate
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
double pulseEB = 2 x 1 mJ∆t = 2 µs
triple pulseEB = 3 x 0,66 mJ∆t 1 = ∆t 2 = 2 µs
=250ns =5µs =15µs
single pulseE= 2 mJ
1 mm
t del t del t delProcess analysis by high speed photography
Pulse bursts:
ResultsPlasma of pulse bursts strips of the surfaceMagnification factor of the plasma volume:10 for double pulse, 15 for triple pulsePlasma emission of pulse bursts have larger
emission times
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
High-speed Microstructuring of Copper, Aluminum and Steel
Average Power at the Sample Surface, Pt 26 WMaximum Average Pulse Peak Intensity, IP 92 MW/cm2
M2 - Value (focused beam) 1.6Repetition Rate, f 4.1 MHzWavelength at Workpiece λ 532 nmPulse Duration, τp 13 ps
OscillatorAmplifier
Frequency Conversion Beam
Dump
Focusing Optics and Scanners
Sample
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
ResultsTop view Top view Cross-section view
Copper
Steel
Aluminium
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Ablation Experiments at FEL
A: ablation experiments in steel 1.4301 (=304) and C70A1: single pulse ablation
different pulse delays (=rep. Rate.)variation of: - pulse energy
- pulse overlap - wavelength
A2: ablation with pulse burstsdifferent delays: • pulse delay during one burst
• burst delayvariation of: - number of pulses per burst (1,2,5, …)
- burst energy- pulse overlap - wavelength
High-speed-photography of plasma dynamicsmetallography, SEM and optical microscopy
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
U:\PC_WNDWS\VORLAGEN\LLT_1.pot
Drilling with µs-laser radiation
Lena Trippe
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Drilling at LLT / ILT with laser radiation
state of the art: single pulse and trepan drilling with µs-laser-radiation
stainless steel, nickel-based superalloy cylindrical hole geometryresolidified melt layers ≤ 15µmaspect ratio ≡ 20 : 1time / hole < 20s (trepan drilling)
Nd:YAG Slab Laserpulse duration: 100-500µsmax. pulse power: 2kWfocal diameter: 40µmM² < 2
aim: expansion of process limits during percussion drilling (high speed drilling)
metals and ceramicsmaterial thickness 5mmaspect ratio > 100 : 1time / hole 1s
interdepartmental cooperation of core competence teams:
process know-howlaser techniquessystem technologymodelling and simulation
process limits
understanding of processes
process diagnostic
process monitoring
process control
modelling,analysis
simulation,numerical
approximation
1mm
60µm
single pulse drilling (X5CrNi18-10)
4mm
α=60°, ∅200µm
trepan drilling (CMSX-4)
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Adaptation of processing parameters
< 500nm ablation depth/pulse < 1-5mm< 3mJ pulse energy < 0.1-50J< 1.5mm material thickness < 10mm
qualitycomplete removal of materialgeometry...
productivityablation rate
...vapourisation
helicaldrilling
melting
percussiondrilling
10µs100ns
?
pulseduration
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Process know-how / laser techniques
variation of parameters:pulse energypulse durationtemporal pulse shape focal positionrepetition rate...
development of hole geometryduring one pulse
single pulse drillingNd:YAG-Slablaserpulse energy: 180mJpulse duration: 200µsmaterial: X5CrNi18-10
purposes:reduction of recast layers andclosurescylindrical geometry of hole
=> parameters for percussion drilling
cross-section of single pulse drillings
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Process analysis by high speed photography
plasma(spikes)
melt / closure atthe hole entrance
pulse shape
200µ
m
-200 0 200 400 600 8000,0
0,1
0,2
0,3
0,4
0,5
0,6
inte
nsity
[a.u
.]
t ime [µs]
single pulse 500µs, 500mJ, dt=20µshole diameter
decreasing intensity oflaser radiation
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Modeling and simulation
-30 0 30 60 90 120 150 180 210 2400
100
200
300
400
500
600
700
800
900
hole
dep
th [µ
m]
t ime [µs]
experiment simulation
-30 0 30 60 90 120 150 180 210 240-1
0
1
2
3
4
5
6
7
8
9
inte
nsity
[a.u
.]
t ime [µs]
time scales of physical processes:beginning of meltingand vapourisationtime until meltflow becomes stationary
geometrical scales:hole depthdepth where resolidification occurshole diameter
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Drilling experiments at FEL
vapourplasma
absorption
laserradiation
Analysis of physical processes
absorption of laser radiation (vapour, plasma) at different wavelengths plasma formation and absorption of laserradiation at different pulse numbers and delaysdevelopment of hole geometrydepending on pulse numbers
⇒ find timescales and geometrical scales in comparison to drilling with µs-pulses
melt
material
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Drilling experiments at FEL
B: drilling experiments (metals (X5CrNi18 10, CMSX-4, Al, Cu), ceramics (Si3N4, AlN))
B1: single burst drillingvariation of: - number of pulses (1,2,5,10,20,50,100)
- different pulse delays- pulse energy- wavelength
B2: multi-burst drillingvariation 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 dynamicsmetallography, SEM and optical microscopy
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
U:\PC_WNDWS\VORLAGEN\LLT_1.pot
Pulsed Laser Deposition
Leonid Moiseev
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Pulsed Laser DepositionAnti reflective coating (ZrO2, Al2O3) on arrays of cylindrical lenses of PMMA
Ferroelectric thin films (BaTiO3, PZT)
BaTiO3
PtSi
cladding
electro-opticQ-switch
Er:BaTiO3
laser mediumEr:BaTiO3
substrate
Q-switch waveguide laser by PLD and microstructuring
BaTiO3 thin films on Si/Pt
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Pulsed Laser Deposition
target
processing gas
substrate
Laser radiation
plasma/vapour
Plasma expansion during PLD
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Spectroscopy on laser-induced plasmas
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Time-resolved plasma emission spectroscopy
∆λ:1 nm d=5 mm
Distance
Relative intensity IA,λ /Im [a.u.]
100 Pa
20 Pa
10 Pa
2 Pa
td/µs=p=
0.5 1 2 5
High speed photography with imaging spectrometerAl lines at 395 nm during ablation of Al2O3 in O2
High speed photography after Abel inversionmaterial: Al2O3, gas: O2
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Heat conduction in the target and absorption by the plasma
0 1 2 3 40
20
40
60
80
100
BaTiO3
Heat conduction in target absorption by plasma
Parti
tioni
ng o
f opt
ical
ene
rgy
P [%
]
Fluence εL [J/cm2]
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Kinetic energy of the particles
Model: Comparison with plume dynamics by iCCD:
• elastic collisions
Tprc
mcE
L
iikin
ε
3
2
1
1+=
, [1]
• inelastic collisions (macroscopic)
23
2
1
1
+
=
Tprc
mcE
L
iikin
ε
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 3 40
5
10
15
20
Collision kinetic models c2=16 x 1010 K/m2
inelastic, v0=18 km/s elastic, v
0=15 km/s
ZrO2
O2, m=32
εL=3 J/cm2
T=20 °C
2 Pa 7 Pa 10 Pa 20 Pa 100 Pa
Mea
n ve
loci
ty <
v> [k
m/s
]
Distance from target R [cm]
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Ellipsometry: Refractive index of ZrO2 films
5 10 30 1001.2
1.4
1.6
1.8
2.0
2.2
2.4
Zone 3Zone 2Zone 1
k nd
S=3,5cm; ε
L=3,5J/cm2
dS=2,7cm; ε
L=3,5J/cm2
dS=2,7cm; ε
L=5,0J/cm2
0.00
0.02
0.04
0.06
0.08
0.10
Calculated kinetic energy <Ekin
>Zr
[eV]
Absorption index k (λ=633 nm)R
efra
ctiv
e in
dex
n (λ
=633
nm
)
TS=20 °CεL=3.5 J/cm2
The bulk values n=2.2 and k=0are achieved at <Ekin>=20 - 50 eV
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Deposition Experiments at FEL
C: deposition experiments of oxides and fluoridesC1: ablation for plasma diagnostics
optical emission and absorption spectroscopyvariation of: - different pulse delays
- pulse energy- wavelength
C2: pulsed laser deposition with pulse burstsmeasurement of deposition rate, optical and structural film
properties and correlation with plasma parametersvariation of: - number of pulses per burst
- burst energy- wavelength
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Aim of all planned Experiments & ConclusionAnalysis of physical processes ablation
process efficiency: absorption of laser radiation in vapour/ plasma at different wavelengths and pulse energies,
kinetic energy of particles: plasma expansion and absorption of laser radiation using different pulse numbers, delays and energy
correlation of the physical processes with the resulting deposition/ablation rate and film properties
modelling of the processes using the FEL-parameters
Find out parameters forthe deposition of high quality films at high deposition rates (>1 µm/s/cm2) the ablation/drilling with tailored pulse trains to precondition the surrounding
getting melt-free structures
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Aachen and ILT
Rathaus Dom
Carl der Grosse
Marktplatz
ILT&LLT
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Adaptation of processing parameters
fs-pulses: lower ablation ratehigh quality
ms-pulses:high ablation ratelower quality
tpt-project: high ablation ratehigh quality
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LEHRSTUHL FÜR LASERTECHNIK
RHEINISCH-WESTFÄLISCHETECHNISCHEHOCHSCHULEAACHEN
Modeling and simulation
Model for ablation process:Following pulses again interact with the surfaceVPB >> VSP, mPB >> mSPdrSP/dt < 0, drPB/dt > 0single pulse: spheric →discoidpulse burst: discoid →spheric
consequence of the precondition due to the previous pulses