The document summarizes an investigation into the microstructural morphological changes of materials (Au, Al, Pt, Cu, Si, ABS) when irradiated with a nanosecond laser. Key findings include: 1) Microstructures like ripples, craters, and microdroplets formed on irradiated surfaces, with gold showing both ripples and a crater. 2) The heat affected zone area, crater depth, crater area, crater volume, and ablated mass all increased with more laser shots. 3) Trends in these measurements differed between materials, but generally increased exponentially, polynomially, or boltzmann with more laser shots.

2. Investigation on Microstructural Morphological
Changes for Laser Irradiated Targets
Presented By:
Tehseen Naz
2012/II-M.phil-App-Phy-09
Supervised By:
Prof. Dr. Anwar Latif
Department of physics,
University of Engineering and Technology,

3. Contents
Objectives
Introduction
Experimentation
Characterization
 Results and Discussion
Conclusions
Applications
Future work
3

4. Objective
 To Investigate the evolution of
microstructures at the surface of nano second
laser irradiated materials (Au, Al, Pt, Cu, Si,
ABS).
4

5. Introduction
Laser Matter Interaction
Interaction of nanosecond laser pulse
with matter causes:
 Absorption
 Thermal excitations
 Melting
 Microstructure growth
 Material ablation [1]
Figure 1: Interaction of ns laser pulse
with matter.
5
[1] Dolgaev, S.I. Kirichenko, N.A. Simakin, A.V. & G.A. Shafeev, “Laser assisted
growth of microstructures on spatially confined substrates”, Applied Surface Science,
253, 7987 – 799 (2007).

6. 6
The interaction of nano-second laser
with target material may produce [2]:
 Ripples
 Micro-droplets
 Cracks
 Crater
 Debris
Continued…
[2] D.Bauerle, Laser processing and chemistry 3rd Edition (Spring-Verlag Berlin,
2000) 215-217.

7. Experimentation
7

8. Experimental Conditions
Targets
4 N pure fine polished
Copper, aluminum,
platinum, gold, Silicon (P-
type) and Acrylonitrile
butadiene styrene (ABS)
Nd:YAG Laser (1064nm,10mJ, 9-12ns, 1.1
MW)
IR- Transmission Lens Focal length (f ) = 8cm
Number of laser shots 25, 50, 75, 100, 125, 150
Atmosphere Ambient air
Table 1: Experimental conditions for material
irradiations.
8

9. Figure 2: Schematic diagram of laser irradiation on targets.
Experimental Setup
9
Nd:YAG Laser
Target Holder Stand
Target Material
Focusing Lens
8cm
Focused Laser Beam

10. Characterization Technique
 Optical Microscope
(Olympus STM 6 with minimum read out of 0.1 µm)
To explore the surface morphology of the targets.
10

11. Results and Discussion
11

12. Surface Morphology of Copper
12
Figure 3: Optical micrographs of Cu irradiated by (a) 25 (b) 50 (c) 75 (d)
100 (e) 125 (f) 150, laser shots.
Area of
HAZ
(b)
Crater
Area of HAZ
(a)
Crater
Area of
HAZ
(c)
Crater
Area of
HAZ
(d)
Crater
Area of
HAZ
(e)
Crater
Area of
HAZ
(f)
Crater

13. 13
Sr no. No. of
laser
shots
Area of
HAZ
(μm2)
Crater
depth
(10-3) μ
m
Crater
area
(10-12
m2)
Crater
volume
(10-21
m3)
Ablated
mass
(10-21
Kg)
1 25 177128.4 14.2 746.1996 10596.03 94940470
2 50 189253.4 26.6 933.8506 24840.43 222570216
3 75 224442.7 57.9 1683.995 97503.3 873629564
4 100 251736.4 67 1734.868 116236.2 1.041E+09
5 125 274585.5 78.9 2618.948 206635 1.851E+09
6 150 298685.9 90 3377.419 303967.7 2.724E+09
Continued…
Table 2: HAZ, crater and ablated mass with increasing the number of laser shots.

14. Surface Morphology of Platinum
14
Figure 4: Optical micrographs of Pt irradiated by (a) 25 (b) 50 (c) 75 (d)
100 (e) 125 (f) 150, laser shots.

15. 15
Sr no. No. of
laser
shots
Area of
HAZ
(μm2)
Crater
depth
(10-3) μ
m
Crater
area
(10-12
m2)
Crater
volume
(10-21
m3)
Ablated
mass
(10-21
Kg)
1 25 4024.35 0.1 13568.38 1356.838 29104172
2 50 8420.511 2.4 17065.22 40956.52 878517342
3 75 8608.529 27 17932.73 484183.6 1.039E+10
4 100 9455.374 29.5 20756.38 612313.2 1.313E+10
5 125 10257.06 34 22735.52 773007.6 1.658E+10
6 150 11955.4 34.2 25850.42 884084.4 1.896E+10
Continued…Table 3: HAZ, crater and ablated mass with increasing the number of laser shots.

16. Surface Morphology of Aluminum
16
Figure 5: Optical micrographs of Al irradiated by (a) 25 (b) 50 (c) 75 (d)
100 (e) 125 (f) 150, laser shots.
Area of
HAZ
Area of
HAZ
Area of
HAZ
Area of
HAZ
Area of
HAZ
Area of
HAZ
Crater
CraterCraterCrater
Crater
(a) (b) (c)
(d) (e) (f)

17. 17
Sr no. No. of
laser
shots
Area of
HAZ
(μm2)
Crater
depth
(10-3) μ
m
Crater
area
(10-12
m2)
Crater
volume
(10-21
m3)
Ablated
mass
(10-21
Kg)
1 25 30047.23
2 1063.263 2126.527 5741621.8
2 50 31267.19
4.8 1338.255 6423.624 17343785
3 75 32162.32
8.1 3634.566 29439.99 79487965
4 100 36335.52
9.4 4298.917 40409.82 109106502
5 125 50325.07
14 4877.911 68290.75 184385025
6 150 51775.86
30 6139.814 184194.4 497324896
Continued…
Table 4: HAZ, crater and ablated mass with increasing the number of laser shots.

18. Surface Morphology of Gold
18
Figure 6: Optical micrographs of Au irradiated by (a) 25 (b) 50 (c)
75 (d) 100 (e) 125 (f) 150, laser shots.

19. 19
Sr no. No. of
laser
shots
Area of
HAZ
(μm2)
Crater
depth
(10-3) μ
m
Crater
area
(10-12
m2)
Crater
volume
(10-21
m3)
Ablated
mass
(10-21
Kg)
1 25 76574.96 22 0 0 0
2 50 169849.3 23 3649.418 83936.61 1.62E+09
3 75 178786.8 23.7 3895.001 92311.52 1.782E+09
4 100 182392 24.8 3983.038 98779.35 1.906E+09
5 125 190010.2 26.8 7839.187 210090.2 4.055E+09
6 150 191134.2 27 16619.69 448731.7 8.661E+09
Continued…
Table 5: HAZ, crater and ablated mass with increasing the number of laser shots.

20. Surface Morphology of Silicon
20
Figure 7: Optical micrographs of Si irradiated by (a) 25 (b) 50 (c) 75 (d)
100 (e) 125 (f) 150, laser shots.
Crater
Reflectio
n
patterns
(f)
Crater
Reflectio
n
patterns
(e)
Crater
Crater
Reflection
patternsReflection
patterns
Crater
Reflection
patterns
(d)
Crater
(a) (b) (c)

21. 21
Sr no. No. of
laser
shots
Area of
HAZ
(μm2)
Crater
depth
(10-3) μ
m
Crater
area
(10-12
m2)
Crater
volume
(10-21
m3)
Ablated
mass
(10-21
Kg)
1 25 8420.511 6.7 10556.55 70728.89 164091019
2 50 15486.46 8 12264.06 98112.44 227620862
3 75 22826.04 18.4 12429.49 228702.7 530590182
4 100 30850.07 45 14377 646964.9 1.501E+09
5 125 34919.18 46 16472.49 757734.7 1.758E+09
6 150 44382.7 76 16981.73 1290612 2.994E+09
Continued…
Table 6: HAZ, crater and ablated mass with increasing the number of laser shots.

22. Surface Morphology of Acrylonitrile
Butadiene Styrene (ABS) Polymer
22
Figure 8: Optical micrographs of ABS irradiated by (a) 25 (b) 50 (c) 75
(d) 100 (e) 125 (f) 150, laser shots.
(a)
(d)
(b) (c)
(e) (f)Crate
r
Crate
r
Area of
HAZ
Area of
HAZ
Area of
HAZ
Area of
HAZ
Area of
HAZ
Area of
HAZ

23. 23
Sr no. No. of
laser
shots
Area of
HAZ
(μm2)
Crater
depth
(10-3) μ
m
Crater
area
(10-12
m2)
Crater
volume
(10-21
m3)
Ablated
mass
(10-21 Kg)
1 25 415.265 100 139.5522 13955.22 15071641
2 50 551.2663 220 10661.74 2345584 2.533E+09
3 75 5024 380 12266.78 4661377 5.034E+09
4 100 5182.227 530 14166.79 7508399 8.109E+09
5 125 5246.204 620 16809 10421579 1.126E+10
6 150 6148.316 630 23775 14978250 1.618E+10
Continued…Table 7: HAZ, crater and ablated mass with increasing the number of laser shots.

24. Graphical analysis
24

25. Comparison of HAZ of irradiated
materials (Al, Au, Pt, Cu, Si, ABS)
25
Figure 9:A plot between area of HAZ and number of laser shots.

26. Comparative graph between crater
depth and number of laser shots
26 Figure 10:A plot between crater depth and number of laser shots.

27. Comparative graph between crater
area and number of laser shots
27
Figure 11:A plot between crater area and number of laser shots.

28. Comparative graph between crater
volume and number of laser shots
28
Figure 12:A plot between crater volume and number of laser shots.

29. Comparative graph between ablated
mass and number of laser shots
29
Figure 13:A plot between ablated mass and number of laser shots.

30. Conclusions
30
 Microstructures (ripples, crater and micro droplets) are
formed on irradiated surfaces.
 All targets (Au, Al, Pt, Cu, Si, ABS) show a small crater
formation but Au shows ripples with crater.
 Area of HAZ, crater depth, crater area, crater volume and
ablated mass increases by increasing number of laser shots.

31. 31
Sr.
No
.
Material
Name
Trends
No. of laser
shots Vs
area of HAZ
No. of
laser shots
Vs Crater
depth
No. of laser
shots Vs
Crater area
No. of laser
shots Vs
Crater
volume
No. of laser
shots Vs
Crater
ablated mass
1 Au Exponential Exponenti
al
Exponential Exponentia
l
Boltzmann
2 Pt Exponential Boltzmann Polynomial Exponentia
l
Exponential
3 Al Boltzmann Exponenti
al
Exponential Exponentia
l
Exponential
4 Cu Linear Boltzmann Exponential Polynomial Boltzmann
5 Si Linear Exponenti
al
Boltzmann Exponentia
l
Exponential
6 ABS Boltzmann Polynomi
al
Exponential Exponentia
l
Exponential

32. Applications:
Surface microstructuring is addressing significant
areas of research like
• Ripple transmission grating [3]
• Data storage devices
• Corrosion protection [4]
32
[3] H.Y. Zheng, T.T. Tan, W. Zhou, “Studies of KrF laser-induced long periodic
structures on polyimide”, Optics and Lasers in Engineering, 47, 180–185 (2009).
[4] L. Honga, Ruslia, X.C. Wangb, H.Y. Zhengb, H. Wanga, H.Y. Yuc,
“Femtosecond laser fabrication of large-area periodic surface ripple structure on
Si substrate”, Applied Surface Science , 297 , 134–138 (2014).

33. Future Work
Comparison of electrical, optical, surface and
morphological properties under the same
conditions on different class of materials can be
performed and the correlation may be formed
between irradiated and un-irradiated materials by
varying different parameters.
33

34. 34