Fibre Lasers for Medical Devices and Applications · Not to be distributed without prior consent of...

Fibre Lasers for Medical Devices and Applications

EPMT Conference, Lausanne, CH26th May 2011

Presenter: Dr Steve Norman, CTO, SPI Lasers

Agenda

● Medium-power ~1µm CWM fiber lasers

● Design and benefits overview

● Application requirements and performance

● Advanced manufacturing applications in medical devices

● Tube cutting: Stents and devices

● Medical device welding

Not to be distributed without prior consent of SPI Lasers

● Medical device welding

● Prosthesis manufacture using metal-powder laser sintering.

● 1.55µm Fibre lasers for direct medical applications

● Choice of laser wavelength, e.g. in dermatologicial treatments

● Laser design / performance overview

● Example application: medical aesthetics

● Summary & Conclusions

R4 CWM Laser Systems


100 – 400W Water CooledFeatures

- CW or Modulated to 100 kHz (modulated pulses <10µs to CW)

-TEM00 (M² <1.1), BPP < 0.37 mm.mrad

- Low moded ( M2~4 ) BPP < 1.33 mm.mrad option

- Central Emission Wavelength: 1070 ± 10nm

-High stability laser (typically <±0.5% output power variation)

-Extended Performance Range (XPR) & Pulse Shape Equalisation (PSE)

25 – 200W Air Cooled

R4 Laser System Applications

Application Areas

Micromachining

Rapid prototyping

Anilox engraving / Flexo

Cutting / scribing- Ceramics / silicon


Plastics cutting / welding

Precision soldering

Fine wire balling / welding

Glass/ceramics marking

Scientific: Diamond anvil cell / atom trapping

Thicker section cutting

Welding (M2 ~1.1 and M2 ~ 4 variants)

R4 GTWave® Fiber Laser Technology

HR OC TAP

GTWave®GTWave®(planar monolithic)(planar monolithic)

TAP


PowerMonitor

PumpModule

PumpModule Beam Delivery

Optics(Collimator / Bare fibre)● All-fibre, integrated monolithic design:-

● Patented GTWave side-pumped technology

● High-brightness beam-combined pump modules (~200W / module)

● Beam delivery options for free-space / fused fibre laser combiners

● Power Scalable to 500W+

Pilot laser

Power scaling: 2-Stage GTWave® Architecture

HR OC

Seed Laser

TAP

Power Amplifier




PowerMonitor

PumpModule

PumpModule

PumpModule

PumpModule Beam Delivery

Optics(Collimator / Bare fibre)

PowerMonitor

● All-fibre, integrated monolithic design:-

● Patented GTWave side-pumped technology

● High-brightness beam-combined pump modules (~200W / module)

● Beam delivery options for free-space / fused fibre laser combiners

● Power Scalable to 500W+

M2<1.1 Lasers Beam Quality

Focused Spot @ 400W(using 512mm FL reference lens)

Beam parameters

Parameter Unit 50W 400W

Diameter mm 5.17 5.16

Circularity % 99.1 98.9

M2 - 1.01 1.02

Divergence mrad .28 .31

Astigmatism zR 0.08 0.1

Thermal Lens zR/kW 1.48


Thermal Lens

parameter

zR/kW 1.48

400W Laser output power linearity

0

100

200

300

400

500

0 50 100 150 200 250 300 350 400 450

Set Power ( Watts)

Ou

tpu

t P

ow

er(

Wa

tts

)

Set Power

Linear (Set Power )

Modulation pulse shape control● Precise & stable optical pulse shape control achieved by electronic control of pump diodes

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Sig

na

l (a

rb)

1

2

3

4

5

6

7

8

TT

L T

rig

ger

[V]

Signal

Trigger10kHz 50% DC

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Sig

nal

(arb

)

1

2

3

4

5

6

7

8

TT

L T

rig

ger

[V]

Signal

Trigger100 kHz 50% DC


0.00

0 20 40 60 80 100 120 140 160 180 200

Time (us)

00.00

0.05

0 2 4 6 8 10 12 14 16 18 20

Time (us)

0

1

0

2

4

6

8

10

12

Time

Sig

na

l ( a

rb u

nits

)

TTL Modulation

PSE Mode OFF

PSE Mode ON

PSE: Pulse Shape Equalisation & Pulse Turn-On Control

XPR – Extended Performance Range

(Patent Pending)(Patent Pending)

70kHz Pulse Profiles by Pulse Energy

200W Laser - XPR Configuration

70kHz Pulse Profiles by Pulse Energy

200W Laser - Standard Configuration


Pulse profile broadens with energies < 0.3 mJ

XPR mode maintains pulse profile down to <0.1 mJ

Pulse shape profiling: e.g. welding

● Using the analog I-O setpoint and trigger inputs

● Output waveform can be controlled for process optimization

eg:

● Welding: Controlled melt pool cooling

● Cutting: Overshoot/heating


● Cutting: Overshoot/heating Example Welding Profile

-100

0

100

200

300

400

500

0 0.005 0.01 0.015 0.02

Time, s

Po

wer,

Watt

s

0

2

4

6

8

10

12

14

16

18

20

Inp

ut,

Vo

lts

Optical

I/P Pulse

Example Welding Profile

-100

0

100

200

300

400

500

0 0.005 0.01 0.015 0.02

Time, s

Po

wer,

Watt

s

0

2

4

6

8

10

12

14

16

18

20

Inp

ut,

Vo

lts

Optical

I/P Pulse

Pulse to pulse stability

Pulse Energy Distribution for 10Hz, 50msec pulses at 100W

20

30

40

50

60

70

80

90

No

. P

uls

es

Min 4.832J

Max 4.882J

Avg 4.857J


0

10

20

4.81 4.82 4.83 4.85 4.86 4.87 4.89 4.90 4.91 4.93

Pulse Energy (mJ)

Max 4.882J

Sigma 0.007J

68.26% of all pulses are within ±0.007J of 4.857J (0.15%)95.46% of all pulses are within ±0.014J of 4.857J (0.31%)99.73% of all pulses are within ±0.021J of 4.857J (0.46%)


Applications Considerations & Examples

Process Dependencies

Dynamic rangePower


Pulse shape

Beam Profile

Stability

Spot Size

Processing Considerations

● The majority of materials processing applications are governed by:-

● Average Power – Determines the amount of thermal energy available to effect any materials processing application

● Pulse Peak Power: Which is typically required to initiate coupling and to overcome processing thresholds.


to overcome processing thresholds.

● Pulse energy & Duration: Which impacts the material interaction

● Power Density & Beam Profile – which reflects the intensity of the laser energy on the substrate.

● It is a combination of all four of these parameters that needs to be considered in laser materials processing applications.


Dynamic

range

Pulse shape Stability

Power


Pulse shape

Beam Profile

Stability

Spot Size

Spot size control and optimization

● Spot size on the workpiece can be controlled by changing the process

head lens focus length and/or the input laser beam diameter

Collimator

Beam Expanding Telescope (BET)

Spot size (um) vs Focus Lens FL and beam expansion

Focus Lens Focal Length (mm)


Telescope (BET)

Focus Lens

FL

Focus Lens Focal Length (mm)

BET x 80 125 150 200

0.7 34 54 65 86

1 24 37 45 60

1.4 17 27 32 43

2 12 19 23 30

2.8 9 13 16 12

Gaussian or Flattened Beam Profile: M2=1 or M2~4?

● Application optimized beam profile

● Cutting

● Precision thin section cutting, fine kerfs in sub 1mm materials

● General thicker section ( 1 - 4mm ) cutting

● Welding: M2 ~ 4

● Narrow or wider profile – Application Dependent


● Narrow or wider profile – Application Dependent

● Uniform energy distribution ═► Improved process control

● Larger spot size ═►Relaxed piece part tolerances

M2 ~ 1.1

M2 ~ 4

Typical Fibre Laser Applications & Ideal Beam Shapes

• Fine kerf cutting / Micromachining

• Rapid prototyping

• Printing: Anilox engraving / Flexo

Single-mode M2<1.1

Low Moded M2~4


• Printing: Anilox engraving / Flexo

• Cutting / scribing- Ceramics

• Fine wire balling / micro welding

• Thicker section cutting

• Welding

•Plastics cutting / welding


Dynamic rangePower


Pulse shape

Beam Profile

Stability

Spot Size

M2<1.1 Micromachining / Fine tube cutting

Cutting Nitinol Coronary Stents - 100W 1.8mm Titanium 0.5mm Nitinol - 400W


● High beam quality allows very fine kerf as low as 15um width

● Cutting speeds with conventional solid state lasers are limited by repetition rates of a few kHz

● Modulation capability up to 100kHz

● Higher speed cutting process achieved, lower thermal effects

Productivity improvements >5x in cutting speeds achieved

● 400W, M2<1.1 laser enables thicker-wall medical devices

Medical Device Manufacturing: Case StudiesMedical Device Manufacturing: Case Studies

● Problem:

● Shrinking device size

● Expensive components, i.e. pacemaker can welding

● Manufacturing in high cost areas requires high throughput, small

footprint, 24/7 operation, reduced maintenance


● Fiber lasers offer solutions:

● Excellent beam quality allows smaller feature size, higher

throughput

● Excellent stability enables higher reproducibility, increased yields

● No maintenance, high reliability

Stent Manufacturing: Fine-Tube Cutting Process


Stent Manufacturing: Case study

● Requirements:

● Iincrease in manufacturing capacity

● Improvement of quality & yield

● Reduced operational / maintenance costs

● Fiber laser benefits:

● Higher cut speed due to direct laser modulation


laser modulation

● Up to 30% increase in throughput

● Better cut quality

● Higher yield, shorter post processing

● Smaller size● Double throughput per square metre of

laser facility

● No maintenance● No laser downtime, no maintenance

cost

>100 lasers in use 24x7 since 2006 with outstanding reliability

Stent Manufacturing: Cost Benefits of Fiber Laser

Conventional Nd:YAG laser

● <3% efficiency

● 1 billion shots / flashlamps

Fiber Laser

● 25% efficiency

● $7.5k pa electricity savings

(12c/kWh)

● No flashlamps


● 1 billion shots / flashlamps

requires weekly – biweekly

flashlamp replacement

● >1m2 clean-room floor space

● No flashlamps

● $10-15k pa savings for

replacement parts

● No laser technician required

● <1m2 space

● VERY significant capital cost

saving in cleanroom space


Dynamic rangePower


Pulse shape

Beam Profile

Stability

Spot Size

Detail cutting- HAZ control

1

2

34

5


● Speed reduction in detail sections �� requires management of heat input to limit heat affected zone (HAZ)

34

Velo

city

Time

1 2 3 4 5

Precision cutting with HAZ control via PSO (Position Synchronized Output)

CNC PSO Output

4

5

6

TT

L S

ign

al (V

)

● Position Synchronized Output

( PSO ) :-

● Motion system detects ∆x

position change from encoder

outputs � …

● TTL trigger signal with preset

100%Ave

rag

e P

ow

er


0

1

2

3

-0.015 -0.01 -0.005 0 0.005 0.01 0.015Clock

TT

L S

ign

al (V

)

● TTL trigger signal with preset

pulse width � …

● TTL pulse triggers laser output

� …

● Laser average power

controlled by pulse

frequency.

0%

50%

Ave

rag

e P

ow

er

Position synchronized triggering

controls HAZ at low speed.

Precision Contour Cutting & HAZ control:Power control via Modulation

CW

Modulated


● Detailed contour cutting requires lower speed and lower average power to

minimize HAZ around corners

● Modulation capability provides wide range of pulse widths <10us to CW

allowing a wide process window

● Process control optimised using by fixed pulse width with variable modulation

frequency controlled by speed or position reference of motion system

Precision Profile Cutting using PSO


Courtesy of Miyachi Unitek

Quality Improvements in Cutting / welding of precision medical tools


Fiber Laser Cutting vs Electro-Discharge Machining


● Visual CMM showing fiber-laser cut part next to the original Wire EDM processed part

● Quality difference between the two.

● Function is improved: Clean, straight cut provides greatly superior column strength since it closes like a shut spring.

● Cost benefit: Laser cut part was much less expensive than the Wire EDM'd part. A great example of using fiber laser technology to solve a manufacturing problem.

Laser-Cut Part EDM Part

Thicker Tube Cutting: 1.25mm Stainless Steel


Wall thickness of this tube >1.25mmCut with 200W CWM laser

Cut speed for 1.25mm wall was same as for 0.125mm wall In cutting small scale parts most of the motion is tied up withacceleration and deceleration of rotation / traverse

Welded-Wire “Crown” Stent

● Manufacture of Welded Stents


● Wire rings are mechanically deformed into crowns

● The wire “crowns“ must be accurately positioned and pushed

together before welding with a precisely controlled laser pulse.

● Typical power settings are in the range 40W - 50W with pulse

durations in the range 5-10ms

Welded-Wire “Crown” Stent

● Example: Welded Stent


Medical Devices - Weld quality is everything

Weld approx. 0.1 mm wide

Weld smoothness is key

� Sterilizable


Selective Laser Melting (SLM) RapidManufacturing System: Medical


To dramatically reduce lead times / produce high value and low volume

parts

To produce precision parts that could not be made or are very costly to be

tooled due to constructional features

Example “Mainstream” Application Example “Mainstream” Application for Generative Microprocessing / Manufacturingfor Generative Microprocessing / Manufacturing

OneOne--off piece parts: off piece parts: Dental Caps!Dental Caps!


Titanium & Cobolt Chrome Medical Implants

High Value , bespoke (low volume) part production


Replacement knee joint in EOS CobaltChrome MP1

Picture Courtesy of MTT UK

Medical Lasers

● 1550 nm wavelength is preferred to 1070nm

● 1550nm absorbed in water

● Can be used to treat skin & subcutaneous layers

without surgical procedures


● Uses in:-

● Dermatology (“Fraxel”) treatment

● Vein Closure

● Micro Surgery

● Veterinarian Medicine

● Hair removal

100

1000

10000

100000

Ab

so

rpti

on

Co

ef.

(1

/cm

)

Water Absorption Spectrum500nm to 3µµµµm

2.95µm

Er:FiberLaser

1.55µµµµm

Er:YAGLaser

Ho:YAGLaser2.1µm

Thulium Fibre Laser 2um


0.01

0.1

1

10

500 1000 1500 2000 2500 3000

Wavelength (nm)

Ab

so

rpti

on

Co

ef.

(1

/cm

)

1.06µm

1.55µµµµm

Nd:YAGLaser

1.32µm

SKIN REJUVENATION

CO2

EF

FE

CT

IVE

NE

SS

High

FRAXEL

ProcessERBIUM-YAG


NON-ABLATIVE

TechniquesEF

FE

CT

IVE

NE

SS

SAFETYHighLow

CHEMICAL PEELS RF

Gain spectra of Erbium-Doped Fibers

Gain

[d

B/m

]

2

3

4

5

6

7

8

PreferredBand

Er Fibers: Emission Spectrum


Wavelength [nm]

960 980 1460 1480 1500 1520 1540 1560 1580 1600 1620 1640

Gain

[d

B/m

]

-8

-7

-6

-5

-4

-3

-2

-1

0

1

1550nm Fibre Laser For Medical Aesthetics OEM Lasers for Skin Rejuvenation

1550nm / 1565nm OEM Laser


Laser Treatment

CW Power: 10W / 20W / 25WWavelength: 1550nm / 1565nm

Mode: CW and ModulatedPower Tuning: 10 – 100% (CW)

Max modulation speed: 3kHzLinewidth FWHM: < 2nm

Output Beam CharacteristicsBeam dia. : 5mm nom

Full angle divergence: <0.6mradM2: <1.2

Courtesy of Sellas, Korea

-40

-30

-20

-10

Po

we

r L

ev

el, d

B

1565_vset050

1565_vset075

1565_vset100

1565_vset125

1565_vset150

1565_vset175

20W 1565nm Fibre Laser: Spectral Properties


-100

-90

-80

-70

-60

-50

1520 1530 1540 1550 1560 1570 1580 1590Wavelength, nm

Po

we

r L

ev

el, d

B

Medical Laser Case Study:Aesthetic Dermatology

� Non-Ablative

� Lower risk of infection

� Tissue is coagulated, not vaporized

� The stratum corneum remains intact

� Fractional

� Multiple 70-150 micron MicroThermal


Laser-based wrinkle removal!

� Multiple 70-150 micron MicroThermal

Zones (MTZs) surrounded by islands of

viable tissue

� Resurfacing

� Extrusion & replacement of damaged

tissue

� Rapid re-epitheliazation (within 24hrs)

� Collagen denatured between 300-750

microns

NON-ABLATIVE FRACTIONAL RESURFACINGusing 1550nm fiber lasers

● Fraxel Technology:

● Treating the skin fractionally with patterns of microscopic laser spots 70-100µm in diameter


● Unique wound healing process results in:● Rapid re-epitheliazation of

the epidermis

● Collagen remodeling to depths of 400-700 microns


Fibre Lasers are Saving Lives

Fibre Lasers Rejuvenate the BodyFibre Lasers Rejuvenate the Body


Fibre Lasers for Medical Devices and Applications · Not to be distributed without prior consent of...

Documents

Transcript of Fibre Lasers for Medical Devices and Applications · Not to be distributed without prior consent of...