A Personal Foreword ........................................... VII
Preface to the First Edition ................................. XIII
Acknowledgment ................................................. XV
1 introduction ................................................. 1
1.1 Motivation .............................................. 1
1.2 Definition of Optical Pump and Probe .................... 4
1.3 Guideline ............................................... 4
1.4 Matrix of Laser Effects and Applications ................ 5
1.5 Historical Survey of Optical Ultra-fast Metrology ....... 6
1.5.1 Metrology Techniques Before the Advent of
Laser ............................................ 6
1.5.2 Ultra-fast Pump and Probe Metrology .............. 7
2 Ultra-fast Engineering Working Tools ........................ 11
2.1 Ultra-fast Laser Sources ............................... 11
2.1.1 General Aspects for Ultra-precise Engineering ... 12
2.1.2 General Aspects on Ultra-fast Lasers for
Ultra-fast Metrology ............................ 13
2.1.3 Laser Oscillator ................................ 15
2.1.3.1 Rod and Disk Solid-State Laser ......... 15
2.1.3.2 Fiber Oscillator ....................... 16
2.1.4 Amplifier ....................................... 18
2.1.4.1 Amplification Media .................... 18
2.1.4.2 Chirped-Pulse Amplification (CPA) ...... 18
2.1.4.3 Optical Parametric Chirped-Pulse
Amplification (OPCPA) .................. 19
2.1.4.4 Amplifier Designs ...................... 20
2.1.4.5 Commercial Systems ..................... 24
2.1.5 Facilities ...................................... 25
2.2 Focusing of Ultra-fast Laser Radiation ................. 26
2.2.1 Ultra-small Laser Focus ......................... 26
2.2.2 Gaussian Beam ................................... 27
2.2.3 Beam Parameters of Gaussian Radiation ........... 29
2.2.4 Pulse Duration .................................. 32
2.2.5 Beam Stability .................................. 34
2.2.6 Key Parameters for Ultra-precision Machining
and Diagnostics ................................. 35
2.2.6.1 Ultra-precise Machining ................ 35
2.2.6.2 Ultra-fast Pump and Probe Diagnostics
for Mechanical Engineering ............. 36
2.3 Beam Positioning and Scanning .......................... 36
2.3.1 Positioning ..................................... 37
2.3.2 Scanning Systems ................................ 39
2.4 New Challenges to Ultra-fast Metrology ................. 41
2.4.1 Temporal Domain ................................. 42
2.4.2 Spatial Domain .................................. 42
2.5 Domains of Optical Pump and Probe Techniques for
Process Diagnosis ...................................... 43
3 Fundamentals of Laser Interaction ........................... 45
3.1 Linear to Non-linear Optics ............................ 45
3.1.1 Linear Optics: Group Velocity Dispersion and
Chirp ........................................... 45
3.1.2 Non-linear Processes ............................ 48
3.1.2.1 Non-linear Polarization ................ 48
3.1.2.2 Self-focusing .......................... 49
3.1.2.3 Spectral Broadening by Self-phase
Modulation ............................. 51
3.1.2.4 Catastrophic Self-focusing ............. 53
3.2 High-Power Photon-Matter Interaction ................... 54
3.2.1 Absorption of Laser Radiation in Matter ......... 54
3.2.2 Energy Transfer from Electrons to Matter ........ 56
3.2.3 Melting and Vaporization ........................ 58
3.2.4 Melt Dynamics ................................... 60
3.2.5 Onset of Ablation ............................... 62
3.2.6 Ionization ...................................... 63
3.3 Matching of Plasma Dynamics on Ultra-fast Time-Scale ... 64
3.3.1 Absorption of Radiation in a Plasma ............. 64
3.3.1.1 Electromagnetic Waves in Plasmas ....... 64
3.3.1.2 Inverse Bremsstrahlung ................. 66
3.3.2 Plasma Heating .................................. 69
3.3.3 Ionization of a Plasma .......................... 72
3.3.3.1 Cross-Section and Collision
Frequency .............................. 73
3.3.4 Electron Transitions and Energy Transport ....... 74
3.3.4.1 The Total Emission ..................... 76
3.3.4.2 The Opacity ............................ 76
3.3.5 Dielectric Function of a Plasma ................. 77
3.3.6 Ponderomotive Force ............................. 78
4 Fundamentals of Pump and Probe .............................. 81
4.1 Ultra-fast Laser Radiation ............................. 81
4.1.1 Beam Propagation ................................ 82
4.1.2 Dispersion ...................................... 82
4.1.3 Coherence ....................................... 83
4.2 Preparation of States and Conditions for Probe Beams ... 85
4.2.1 Preparation of States ........................... 86
4.2.2 Preparation of States by Spectro-Temporal
Shaping ......................................... 86
4.2.3 Measurement of States ........................... 88
4.2.4 Measurement of Radiation Properties ............. 89
4.2.4.1 Pulse Duration ......................... 89
4.2.4.2 Spectral Phase ......................... 90
4.3 Imaging with Ultra-fast Laser Radiation ................ 91
4.3.1 Diffraction Theory and Incoherent
Illumination .................................... 91
4.3.2 Image Formation by Microscopy and Coherent
Illumination .................................... 95
4.4 Temporal Delaying ...................................... 97
4.4.1 Mechanical Delay ................................ 98
4.4.1.1 Single-Pass Delay Stage ................ 98
4.4.1.2 Multi-Pass Delay Stage ................. 99
4.4.1.3 Mechanical Optoelectronic Scanning .... 101
4.4.2 Non-mechanical Delay ........................... 101
4.4.2.1 Free-Running Lasers ................... 102
4.4.2.2 Synchronized Lasers ................... 103
5 Examples for Ultra-fast Detection Methods .................. 105
5.1 Non-imaging Detection ................................. 106
5.1.1 Transient Absorption Spectroscopy (TAS) ........ 106
5.1.1.1 Principle and Setup ................... 106
5.1.1.2 Characterization of the White-Light
Continuum ............................. 108
5.1.1.3 Measurement by TAS .................... 112
5.1.2 Temporal Shaped Pulses ......................... 113
5.1.2.1 Principle and Setup ................... 113
5.1.2.2 Characterization of the Si-Kα-
Radiation Source ...................... 115
5.2 Imaging Detection ..................................... 118
5.2.1 Non-coherent Methods ........................... 119
5.2.1.1 Shadowgraphy .......................... 119
5.2.1.2 Transient Quantitative Phase
Microscopy (TQPm) ..................... 120
5.2.2 Coherent Methods ............................... 124
5.2.2.1 Mach-Zehnder Micro-Interferometry ..... 124
5.2.2.2 Speckle Microscopy .................... 127
5.2.2.3 Nomarsky Microscopy ................... 129
6 Applications of Pump and Probe Metrology ................... 133
6.1 Drilling of Metals .................................... 134
6.1.1 Introduction ................................... 134
6.1.2 Measurement of Ejected Plasma, Vapor and
Melt ........................................... 134
6.2 Microstructuring of Metals ............................ 137
6.2.1 Introduction ................................... 137
6.2.2 Detection of Plasma Dynamics ................... 138
6.3 Marking of Glass ...................................... 140
6.3.1 Introduction ................................... 140
6.3.2 Detection of Laser-Induced Defects ............. 141
6.3.3 Detection of Refractive-Index Changes and
Cracking ....................................... 143
6.4 Welding of Technical Glasses and Silicon .............. 145
6.4.1 Introduction ................................... 145
6.4.2 Detection of Laser-Induced Melting ............. 146
7 Perspectives for the Future ................................ 151
7.1 Laser and Other Sources ............................... 152
7.2 Methodology ........................................... 153
7.2.1 Scanning Technology ............................ 253
7.2.1.1 Spatial Scanning ...................... 153
7.2.1.2 Temporal Scanning ..................... 153
7.2.2 Beam Shaping ................................... 153
7.2.2.1 Spatial Shaping ....................... 153
7.2.2.2 Temporal Shaping ...................... 154
8 Summary .................................................... 155
Appendix A Lock-in Amplifier .................................. 159
Appendix В Onset on Optics .................................... 161
B.l Abbe Sine Condition ................................... 161
B.2 Quantitative Phase Microscopy ......................... 162
Appendix С Plasma Parameters .................................. 165
C.l Transport Coefficients ................................ 165
С.1.1 Electrical Conductivity ........................ 165
С 1.2 Thermal Conductivity ........................... 165
C.1.3 Diffusivity of Electrons ....................... 166
С 1.4 Viscosity ..................................... 167
C.2 Debye Length .......................................... 168
C.3 Plasma Oscillations and Waves ......................... 169
C.4 Coupling Between Electrons and Ions ................... 171
C.5 Hydrodynamic Instabilities ............................ 172
Appendix D Facilities ......................................... 173
Appendix E List of Abbreviations and Symbols .................. 177
E.l Abbreviations ......................................... 177
E.2 Symbols ............................................... 178
References .................................................... 183
Glossary ...................................................... 195
Index ......................................................... 199
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