KR0000024

KAERI/RR-1841/98

Development of delivery system and excitation technique

for Er:YAG laser

3 1 - 1 1

KAERI/RR-1841/98

a||o|*|

Development of delivery system and excitation technique

for Er:YAG laser

"CHS o|7l

1998 fcd 12fl

(S)

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xrfef ^ ^ - ^-ufl^ ^ ^ $<>WW 37)) %-§-£

100*

ffl .

Xe

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cfl

: 500 mJ/pulse

- 3 -

S U M M A R Y

I. Project Title

Development of delivery system and excitation technique for Er:YAG laser

II. objectives and Importance of the Project

The purpose of this project is development of the excitation system and

optical delivery for Er^YAG laser. The demands for infrared laser which shows

a good water absorption have been increased continuously in the field of

medical area. Because of its efficient absorption by water, Er'-YAG laser is

particularly useful for precise localized tissue ablation. Biological tissue

has a high water content, and this, in the absence of pigment, largely

determines its absorption of light and the Er:YAG laser can be particularly

effective in endoscopic microsurgery. However, because silica is only

transparent within a spectral range of about 0.2 tO 2.3 um, the Er:YAG laser

cannot pass through silica fiber. It has been remained as a hot interest in

medical community.

On the basis of technology achieved in previous long term project of laser

research, we are trying to optimize the excitation and evaluate optical deli

very of Er:YAG laser.

- 4 -

III. Scope and Contents of the Project

- Development of lamp excitation technique

: Optimization research of emission spectrum as a function of electrical

current and fill pressure in Xenon flashlamp.

- Development of lamp excitation system

: geometrical design and fabrication of difussive reflector.

- Research for high conversion efficiency of lamp light to laser

radiation.

: Optimization of gain and loss mechanism in Er:YAG laser

- Investigation of optical delivery of Er:YAG laser

: Optical delivery with an articulated arm

IV. Results and Proposal for Applications

Results

- Fabrication of excitation chamber ( 1 unit)

- Investigation of laser parameters of Er'.YAG laser

( Laser efficiency : 0.3*. Output Energy : 500aJ/pulse at 300//S pulse

width)

- Investigation of optical delivery of Er:YAG laser

(1 unit of articulated arm)

Proposal for Applications

- 5 -

In this project, the basic system of Er'-YAG laser has been developed.

Therefore, the basic technology from this project will be used in the further

advanced research program for medical applications.

- 6 -

C O N T E N T S

Chapter 1. Introduction 10

Chapter 2. Flashlamp pumping for Er laser 12

Section 1. Energy level of Er+3 in YAG 12

Section 2. Spectrum of flashlamp 14

Section 3. Flashlamp pumping technique for Er laser 16

Chapter 3. Laser output and its beam delivery 19

Section 1. Experiment for laser output 19

Section 2. Experiment of laser beam delivery 20

Chapter 4. Conclusion 24

Reference 25

- 7 -

10

12

12

14

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2s s a # ^s 20

f a 5 24

25

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l- l- l . #<HH3 313 «-4*^«J 10

2-1-1. Er3* ionSj oflM*l level diagram 12

2-2-1. Er:YAG $]°W$) % ^K* tfl^ ^ -S 13

2-2-2. ^ £ «U3 ^J£ (2900 watt/cm2)6flA^ > ^ ^ ^ ^ - ^ ^ - 5 14

2-2-3. &•& 6 J^ ^ S . (23000 watt/cmzWH2l ^ ^ " ^ ^ - ^ ^ - i 15

2-3-1. ^ f > ^ Sl^Wl^ «UK£ ^ - i 17

2-3-2. *11*^! #&*$ S>4̂ 11 a^a- 18

2-3-3. ^7| | *H*t€ <H^" ^ 1 ^ %<H7] ^ * | 18

3-1-1. Er.YAG B}H*] ^§-^7] ^ - i 19

3-1-2. Er=YAG eflo]^} # ^ ^ J l -^ 19

3-2-1. ^ M ' H ^ ^ ^ ^ Er:YAG j^o]^ ^.^ ^.>g 20

3-2-2. 7 3Hi ^ -n-S- #*1 20

3-2-3. 7 #*1 ^ -H-JE. ̂ * ]5 | 3H*1 ^ 2 f S 22

- 9 -

M

1-1-1

[1-2]

Water Absorption Spectrum

•a

100000

10000

1000

100

10

1

0.1

0.01

0.001

0.00010

/

I\JI

\ 1\ 1

\ I Er:YAQ laser line

\

1,000 2,000 3,000 4,000 5,0

Wavelength (mn)

1-1-1.

=13000 cm"1

(1.06um, a = l cm"1

2.94 um

Ho:YAG

Er:YAG

= 5 0 cm"1 Nd:YAG

endoscope-f-

- 10 -

Er:YAG « f l W j % § l £ ^ f l

^ o l 0.2um - 2.3um ^ | ? 1 ^2}J£7> #

quartz^. 5 } ^ Sg<>?S. 2.94um EriYAG

ZrF, Sapphire fiber •§•#

30-40*

Er:YAG efl^l^^ ^7l(excitation)

- 11 -

2 g-

2.94um

4/ l3 /2

2-1 -

20}

S1 0

0

3*11 2-1-1. Er3t

•

1

1

ii• v

• „3D

Rt R2 W

I 6/2

I It ,'2

level diagram[3]

Er:YAG

Er

2Hn/2 Er

4-level e

2msH

3 7>xl(Ri, R2,

^ ( ^ <550nm)

Er ^S^. YAG doping £J&-§-

ofl

- 12 -

4I15/2

Er multiphonon r e l a x a t i o n s } ^ 7}^

Er

R2 Er

1.5 um

UV

W

4I13 /2 Er MS.

4I1 5 / 2 Er 4I9 / 2 Er

"cross-relaxation"

200 3D0 4C0 500 BCO 700 800 900 1000 UiWAVELENGTH (nn-i)

2-2-1 Er:YAG rfl^

- 13 -

Er:YAG

W ̂ cross-relaxat ion

Envolope: Clear fused Quartz, Ismi

Ace Latvjthi 7.€2cmCircuit Parareters: 500V, 100 pF, 100 uHPulse Repetition Rats: 1 HzCoolimj: Convection

WO 900 «00 900

a) Xenon, 390 Torr

ex TH

,1 ,.is

| ! •

1 * *

Bnvelcpe: Clear Pused Quartz, lineBore Diat 6.0tmtec length: 7.62 onCircuit Parameters; SOW, 100 if, 100 titPulio Repetition Rate: 1 nzOoolingt Convection

jJLM0 tOOO

b) Krypton, 700 fcorr.

2-2-2. (2900 watt/cm2

- 14 -

Sin}.

Er:YAG

Xe. Kr

Xe $ Kr

Kr 7 ^

2-2-2^

infrared)

bound - bound

a) Xeatxii 390 Itotr

is..

Circuit Parameters: 1000V, 200 tr, 52 t*Pulee Repetition fiate IHzCoollog: Convection

b) Krypton, 700 "Sorr

2-2-3. (23000 watt/cm2

- 15 -

2-2-3^ ̂ £ <a«l<HM*l ̂ MQ Xe £

continuum radiation^]

&>] Er:YAG ejlol^e^l ^ c J ^ | A S JL3f^olJELS. Xe ^ S

t h $ ^ ^ o f l ^ S . S7W # ¥ 5 ) Xe lampl- A ]~§-«H 3L2f^*l Er:YAG

71

Xe<>l

triggering 2J- simmer current-^ £^.7\] *fecj{ <^^^.o| ojc}. HZ]3. Xe 7f>i-

4 > Kr 7>>sS A}-§-̂ ttfliLc} JL#^1 #AtH ^ ^

^ f *^ "fl7f D| 3L#o| ^c>. « « -a^^5l bore

j i pulsed ^

7\.

- 16 -

^ Er:YAG

Er:YAG 2l

400nm-1050nm

2-3- Slit}.

im± 2-3-1.

n ^ 2-3-2

- 17 -

m&$*%H ^ 2-3-2

End block

n H 2-3-3

endblock#

connector!-

endblock

3.^ 2-3-3 o|«.

18 -

3 s-

7K

3-1-2

Er:YAG rod

ZL^J 3-1-1 Er:YAG

Hz S , ̂ - ^ g : 300usec

Er:YAG

3-1-3

0.6

0.5^»*—3

">, 0.4w.

C

lU 0.3Q."5 0.2O

0.1

r

• Output Eneig/• Efficiency

0.5

0.4

oca)0.2 |

0.1

40 60 80 100 120 140

Input Energy (J)

plot

3-1-2 Er.YAG

- 19 -

570

0.45* 600V &.M ^>r

dynamic stable

l .

Er:YAG 2.94um o |H

quartzS.

cfl power,

. chalcogenide[4] *£ silver halide

2.3 um

-frss.

700

g-800

1400^300

° 100

0

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0 200 400 GOO 900 1000input Energy (mJ)

H^l 3-2-1 Er:YAG

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«fla

80* 3-2-1) 2m

60-70%

I

ZL^I 3-2-2 7

(articulated am)

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99% % • 93% 95%

70%

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3-2-2 fe

^ ^ 3-2-32}

3 0 0

2 5 0

CJ 200

3" 150

1 0 0

50

150 180 210 240 270 3 0 0

3-2-3 7

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HH 3-2-3

1.5M f 3}

92.7%, 95.8%

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Endblock#

jacket^ 4 ^ 2 3 |

Xenon

600 volt $i^.HS. ̂ cfl 600

^^^-^r «^ 350usec

\%

2.94um iNlol^^ ^ ^ ^ ^ ^ # 7

7

- 24 -

SUSS

[1] Iain D. Miller, The Erbium laser Gains a Role in Cosmetic Surgery,

Biophotonics International, May/June, p38 (1997).

[2] Klaus vogler and Max Rein, Improved Erbium laser Parameters,

Biophotonics International, Nov./Dec.,p40 (1996).

[3] M.Lukac, S. cencic, and K. Nemes, Influence of direc and cross-relaxation

pumping processes on the output energy and thermal load of an Er:YAG

laser, Appl. Opt. 32, No. 36, 7399 (1993).

[4] Q.G. Antipenko, et. al., Use of a Er;YAG laser with a chalcogenide fiber

waveguide in laser surgery, Quant. Electr. 25 (5), 498 (1995).

- 25 -

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BIBLIOGRAPHIC INFORMATION SHEET

Performing Org.

Report No.

Sponsoring org.

Report No.

Standard Report

No.INIS Subject Code

KAERI/

Title/Subtitle

Development of delivery system and excitation technique forEr:YAG laser

Project Manager and Dept. Kwang-Suk Kim (Opto-mechatronics team)

Researcher and Dept.Cheol-Jung Kim(Opto-mechatronics team)

Min-Suk Kim(Opto-mechatronics team)

Pub.Place Taejon Pub. Org. KAERI Pub.Date 1998.12.

Page 25 P. 111. and Tab. Yes(0 ), No( Size 26 Cm

Note'98 Basic Research Project

Classified Open(O ),Outside( ) Class Report Type Research Report

Sponsoring Org. Ministry of Science and Technology Contract No

Abstract(About 300 words)

The demands for infrared laser which shows a good water absorption have been

increased continuously in the field of medical area. The purpose of this project is

development of the excitation system and optical delivery for Er:YAG laser.

Therefore, we are trying to optimize the excitation spectrum of flashlamp to match

the absorption spectrum of laser material well. More than 500mJ of pulse energy has

been obtained with an excitation diffusive chamber. We investigated several

parameters of laser transmission with 7 knuckles articulated arm.

Subject Keywords(About 10 words)

laser, excitation, spectrum, flashlamp, infrared