Acknowledgements	6
	Contents	7
	Abbreviations	8
	List of Figures	10
	List of Tables	25
	Abstract	29
	1 Introduction	31
	1 Generation of Laser Pulses	33
	1.1 Q-Switching	33
	1.2 Function Principle of Q-Switch	34
	1.3 Closing Frequency and Opening Time of the Q-Switch	34
	2 Laser Ablation	35
	3 Micro-channels Applications	36
	4 Problem Definition	39
	5 Research Objectives	40
	6 Research Methodology	41
	7 Research Utilization	42
	2 Literature Review	44
	1 Background	44
	2 Laser Beam Machining (LBM)	45
	2.1 Physical Factors Affecting the Process	45
	2.1.1 Laser Radiation Features	46
	2.1.2 Substrate Material Features	46
	2.2 Laser Ablation Mechanism	46
	2.3 Laser Beam Milling	47
	2.3.1 Ablation Mechanism of Laser Beam Milling	48
	2.3.2 Laser Beam Milling of Titanium Alloys	48
	2.3.3 Laser Beam Milling of Nickel Alloys	49
	2.3.4 Laser Beam Milling of Ceramics and CFRP	50
	2.3.5 Parametric Effects in Laser Beam Milling	50
	2.3.6 Temperatures and Stress Field Distribution	52
	2.3.7 Laser Induced Periodic Structures	53
	2.3.8 Laser Beam Milling with Auxiliary Concepts	54
	2.4 Laser Beam Drilling/Trepanning	54
	2.4.1 Ablation Mechanism in Laser Beam Drilling	55
	2.4.2 Parametric Effects in Laser Beam Drilling	56
	2.5 Dual Beam Laser Machining	58
	2.6 Conclusions and Remarks	59
	3 Laser Assisted Machining (LAM)	59
	3.1 Material Removal Mechanism in LAM	60
	3.2 Parametric Effects and Inspirations of LAM	60
	3.2.1 Cutting Forces and Material Removal Rate	62
	3.2.2 Tool Life and Surface Roughness	63
	3.2.3 Temperature Fields Measurements and Microstructure	64
	3.3 Conclusions and Remarks	66
	4 Laser Chemical Machining/Etching (LCM/E)	66
	4.1 LCM/E Mechanism	67
	4.2 Parametric Effects and Inspirations of LCM/E	68
	4.2.1 Porous Structures	68
	4.2.2 3D Structures	70
	4.3 Conclusions and Remarks	71
	5 Laser Assisted Electrochemical Machining (LAECM)	72
	5.1 Conclusions and Remarks	74
	6 Under-Water Laser Ablation (UWLA)	74
	6.1 UWLA Mechanism	75
	6.1.1 Beam Focus	75
	6.1.2 Water Layer Thickness	75
	6.1.3 Splashing and Cavitation Bubbles	76
	6.1.4 Melt Ejection and Sample Configuration	76
	6.2 Parametric Effects of UWLA	77
	6.2.1 High Ablation Rate	80
	6.2.2 Low Ablation Rate	80
	6.2.3 Possible Reasons of Ablation Rate Variations	81
	6.3 Inspirations of UWLA	81
	6.3.1 Crater Formation and Structure Characteristics	82
	6.3.2 Under-Water Laser Milling	82
	6.3.3 Under-Water Laser Drilling	85
	6.3.4 Synthesis of Nano-particles	86
	6.4 Conclusions and Remarks	89
	7 Micro-channels Applications and Fabrication	90
	7.1 Micro-channel Heat Exchangers	90
	7.1.1 Automotive and Aerospace	90
	7.1.2 Chemical Reactors	92
	Falling-film Micro-reactors	93
	Membrane Separation Technology	93
	Co-current Micro-channel Absorption	94
	7.1.3 Cryogenic Systems	95
	7.2 Laser Diode Applications	96
	7.3 Micro-channel Heat Pipes	96
	7.4 Micro-pulsating Heat Pipes	97
	7.5 Micro-channel Flat Heat Pipes	99
	7.6 Micro-channel Heat Plates	100
	7.7 Micro-channel Fabrication Techniques, Materials, Sizes and Shapes	100
	7.7.1 Fabrication Techniques	100
	7.7.2 Micro-channel Materials	105
	7.7.3 Micro-channel Shapes and Sizes	105
	7.8 Conclusions and Remarks	106
	8 Literature Review Conclusions and Research Gaps	106
	3 Research Methodology	110
	1 Overall Research Methodology	110
	2 Methodology of Initial Parameters Screening	111
	2.1 Defining Ranges and Levels of Parameters	112
	2.2 Defining Fixed and Variable Factors	113
	3 Methodology of Laser Beam Machining Experimentation	114
	3.1 CAD Modeling and Programming Procedure	114
	3.2 Specimen Preparation and Machine Setting	117
	3.3 Experimentation	118
	3.3.1 Pilot Experimentation Without DOE	118
	3.3.2 Mature Experimentation with DOE	121
	4 Measurements Methodology	123
	4.1 Metallographic Specimen Preparation	123
	4.2 Chemical Etching	123
	4.3 Measurements	125
	5 Methodology of Analysis (Modeling, Optimization and Validations)	126
	5.1 Mathematical Modeling	127
	5.2 Multi-objective Optimization	128
	4 Under-Water Laser Beam Micro-milling (UWLBMM) of Aerospace Alloys	130
	1 Introduction	130
	2 Under-Water Laser Beam Micro-milling (UWLBMM)	133
	2.1 Experimental Setup	133
	2.2 Machining Mechanism	139
	2.3 Results and Discussions	140
	2.3.1 Micro-channels Under Low Scan Speeds	140
	2.3.2 Micro-channels Under High Scan Speeds	142
	2.4 Analysis of Parametric Effects	145
	2.4.1 Effect of Scan Speed	145
	2.4.2 Effect of Pulse Repetition Rate	146
	2.4.3 Effect of Laser Power	146
	2.5 Concluding Remarks on UWLBMM	147
	3 Comparison of Under-Water LBMM and Dry LBMM	148
	3.1 Experimental Setup	148
	3.2 Materials and Methods	148
	3.3 Laser Beam Machining Under Dry Conditions	149
	3.4 Laser Beam Machining Under Wet Conditions	151
	3.5 Comparison of Parametric Effects	152
	3.5.1 Effect of Laser Power	153
	3.5.2 Effect of Pulse Repetition Rate	154
	3.5.3 Effect of Scan Speed	156
	3.6 Concluding Remarks on Comparison of Under-Water LBMM and Dry LBMM	159
	4 Limitations of Under-Water Laser Beam Micro-milling	160
	5 Dry Laser Beam Micro-milling (DLBMM) of Aerospace Alloys	162
	1 DLBMM of Nickel Alloy (NA)	164
	1.1 NA 100 × 50 µm Micro-channels	164
	1.1.1 DLBMM of NA 100 × 50 µm	164
	1.1.2 Parametric Effects During DLBMM of NA 100 × 50 µm	165
	1.1.3 Microstructures of NA 100 × 50 µm Micro-channels	167
	1.1.4 Micro-hardness Profiles NA 100 × 50 µm Micro-channels	169
	1.2 NA 200 × 100 µm Micro-channels	172
	1.2.1 DLBMM of NA 200 × 100 µm	172
	1.2.2 Parametric Effects During DLBMM of NA 200 × 100 µm	172
	1.2.3 Microstructures of NA 200 × 100 µm Micro-channels	175
	1.2.4 Micro-hardness Profiles NA 100 × 50 µm Micro-channels	175
	1.3 NA 400 × 200 µm Micro-channels	177
	1.3.1 DLBMM of NA 400 × 200 µm	177
	1.3.2 Parametric Effects During DLBMM of NA 400 × 200 µm	178
	1.3.3 Microstructures of NA 400 × 200 µm Micro-channels	180
	1.3.4 Micro-hardness Profiles NA 400 × 200 µm Micro-channels	180
	1.4 NA 800 × 400 µm Micro-channels	182
	1.4.1 DLBMM of NA 800 × 400 µm	182
	1.4.2 Parametric Effects During DLBMM of NA 800 × 400 µm	182
	1.4.3 Microstructures of NA 800 × 400 µm Micro-channels	184
	1.4.4 Micro-hardness Profiles NA 800 × 400 µm Micro-channels	185
	1.5 NA 1000 × 500 µm Micro-channels	186
	1.5.1 DLBMM of NA 1000 × 500 µm	186
	1.5.2 Parametric Effects During DLBMM of NA 1000 × 500 µm	187
	1.5.3 Microstructures of NA 1000 × 500 µm Micro-channels	187
	1.5.4 Micro-hardness Profiles NA 1000 × 500 µm Micro-channels	188
	2 DLBMM of Titanium Alloy (TA)	191
	3 DLBMM of Aluminum Alloy (AA)	194
	4 Concluding Remarks	197
	6 Dimensional Variations in DLBMM of Aerospace Alloys	199
	1 Basics of Variations and Nomenclature	200
	2 Geometrical Measurements	202
	3 Dimensional Variations Over Micro-channel Sizes	206
	3.1 Dimensional Variations in DLBMM of Nickel Alloy	206
	3.1.1 Parametric Effects on Top Width (?XT)	207
	Effect of Lamp Current Intensity	208
	Effects of Pulse Frequency	208
	Effects of Scan Speed	209
	3.1.2 Parametric Effects on Bottom Width (?XB)	209
	Effect of Lamp Current Intensity	210
	Effects of Pulse Frequency	210
	Effects of Scan Speed	211
	3.1.3 Parametric Effects on Depth (?Z)	211
	Effect of Lamp Current Intensity	211
	Effects of Pulse Frequency	213
	Effects of Scan Speed	213
	3.1.4 Parametric Effects on Taperness (??)	214
	Effect of Lamp Current Intensity	215
	Effects of Pulse Frequency	215
	Effects of Scan Speed	215
	3.2 Dimensional Variations in DLBMM of Titanium Alloy	215
	3.3 Dimensional Variations in DLBMM of Aluminum Alloy	217
	4 Dimensional Variation Over Materials	218
	4.1 Dimensional Variations in DLBMM of 100 × 50 µm Micro-channels	218
	4.1.1 Parametric Effects on Top Width (?XT) of 100 × 50 µm Micro-channels	218
	Effect of Lamp Current Intensity	219
	Effect of Pulse Frequency	219
	Effect of Scan Speed	220
	4.1.2 Parametric Effects on Bottom Width (?XB) of 100 × 50 µm Micro-channels	220
	Effect of Lamp Current Intensity	220
	Effect of Pulse Frequency	221
	Effect of Scan Speed	221
	4.1.3 Parametric Effects on Depth (?Z) of 100 × 50 µm Micro-channels	222
	Effect of Lamp Current Intensity	222
	Effect of Pulse Frequency	223
	Effect of Scan Speed	223
	4.1.4 Parametric Effects on Taperness (??) of 100 × 50 µm Micro-channels	223
	Effect of Lamp Current Intensity	223
	Effect of Pulse Frequency	224
	Effect of Scan Speed	224
	4.2 Dimensional Variations in DLBMM of 200 × 100 µm Micro-channels	225
	4.3 Dimensional Variations in DLBMM of 400 × 200 µm Micro-channels	225
	4.4 Dimensional Variations in DLBMM of 800 × 400 µm Micro-channels	225
	4.5 Dimensional Variations in DLBMM of 1000 × 500 µm Micro-channels	226
	5 Concluding Remarks	226
	7 Mathematical Modeling and Multi-objective Optimization	228
	1 Analysis of Variance (ANOVA) Tests	228
	2 Mathematical Modeling	230
	3 Multi-objective Optimization	230
	4 Modeling and Optimization for Nickel Alloy	232
	4.1 Modeling and Optimization for NA 100 × 50 µm Micro-channels	232
	4.2 Modeling and Optimization for NA 200 × 100 µm Micro-channels	234
	4.3 Modeling and Optimization for NA 400 × 200 µm Micro-channels	236
	4.4 Modeling and Optimization for NA 800 × 400 µm Micro-channels	238
	4.5 Modeling and Optimization for NA 1000 × 500 µm Micro-channels	240
	4.6 Summary of Multi-objective Optimization for Nickel Alloy	242
	5 Modeling and Optimization for Titanium Alloy	243
	5.1 Modeling and Optimization for TA 100 × 50 µm Micro-channels	243
	5.2 Modeling and Optimization for TA 200 × 100 µm Micro-channels	245
	5.3 Modeling and Optimization for TA 400 × 200 µm Micro-channels	247
	5.4 Modeling and Optimization for TA 800 × 400 µm Micro-channels	250
	5.5 Modeling and Optimization for TA 1000 × 500 µm Micro-channels	252
	5.6 Summary of Multi-objective Optimization for Titanium Alloy	254
	6 Modeling and Optimization for Aluminum Alloy	255
	6.1 Modeling and Optimization for AA 100 × 50 µm Micro-channels	255
	6.2 Modeling and Optimization for AA 200 × 100 µm Micro-channels	257
	6.3 Modeling and Optimization for AA 400 × 200 µm Micro-channels	259
	6.4 Modeling and Optimization for AA 800 × 400 µm Micro-channels	261
	6.5 Modeling and Optimization for AA 1000 × 500 µm Micro-channels	263
	6.6 Summary of Multi-objective Optimization for Aluminum Alloy	265
	7 Concluding Remarks	266
	8 Validations—Modeling and Optimization	268
	1 Validation of Predictive Models of Nickel Alloy	268
	1.1 Validation of Predictive Models of NA 100 × 50 µm Micro-channels	268
	1.2 Validation of Predictive Models of NA 200 × 100 µm Micro-channels	271
	1.3 Validation of Predictive Models of NA 400 × 200 µm Micro-channels	273
	1.4 Validation of Predictive Models of NA 800 × 400 µm Micro-channels	276
	1.5 Validation of Predictive Models of NA 1000 × 500 µm Micro-channels	278
	1.6 Validation of Multi-objective Optimization for Nickel Alloy	281
	2 Validation of Predictive Models of Titanium Alloy	281
	3 Validation of Predictive Models of Aluminum Alloy	284
	4 Concluding Remarks	285
	9 Conclusions and Future Work Recommendations	286
	1 Conclusions of UWLBMM	286
	1.1 Conclusions of DLBMM	287
	2 Future Work Recommendations	290
	2.1 Future Work Recommendations for UWLBMM	290
	2.2 Future Work Recommendations for DLBMM	291
	Appendix A	292
	Appendix B	340
	References	353