Preface |
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xi | |
Author |
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xiii | |
About the Cover |
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xv | |
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1 The Interstellar Medium (ISM) at Terahertz (THz) Frequencies |
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1 | (38) |
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1 | (2) |
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1.2 ISM Components of the Milky Way |
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3 | (7) |
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1.2.1 Hot Ionized Medium (HIM) |
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5 | (1) |
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1.2.2 Warm Neutral Medium (WNM) |
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5 | (1) |
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1.2.3 Warm Ionized Medium (WIM) |
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5 | (1) |
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1.2.4 Cool Neutral Medium (CNM) |
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6 | (1) |
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1.2.5 Cold Dense Molecular Clouds (CDM) |
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7 | (1) |
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1.2.6 Relationship between ISM Phases |
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7 | (3) |
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10 | (6) |
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1.4 Probing the Lifecycle of the ISM |
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16 | (16) |
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1.4.1 Origin of Fine-Structure Lines |
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16 | (2) |
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1.4.2 Importance of [ CII] |
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18 | (2) |
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1.4.3 Diffuse Gas Density |
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20 | (3) |
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1.4.4 Star Formation Rate and Infrared (IR) Luminosity |
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23 | (2) |
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1.4.5 Spectral Classification of Ionizing Star |
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25 | (1) |
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1.4.6 THz Molecular Lines |
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26 | (1) |
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1.4.6 1 Rotational Transitions |
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26 | (3) |
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29 | (3) |
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1.5 THz Spectral Energy Distributions (SEDs) |
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32 | (7) |
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34 | (1) |
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35 | (4) |
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2 THz Radiative Transfer Basics and Line Radiation |
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39 | (28) |
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2.1 Equation of Radiative Transfer |
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39 | (2) |
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2.2 Solution to the Equation of Radiative Transfer under Local Thermodynamic Equilibrium (LTE) |
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41 | (7) |
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2.3 Radiative Transfer of Rotational Transitions of Linear Molecules in LTE |
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48 | (12) |
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2.3.1 Determining Gas Optical Depth |
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49 | (2) |
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2.3.2 Derivation of Gas Excitation Temperature |
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51 | (4) |
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2.3.3 Derivation of Gas Column Density with Optical Depth |
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55 | (1) |
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2.3.4 Derivation of Gas Column Density in the Optically Thin Limit |
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56 | (4) |
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2.3.5 Estimating Gas Density and Mass |
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60 | (1) |
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60 | (7) |
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64 | (1) |
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65 | (2) |
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67 | (20) |
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67 | (3) |
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3.2 THz Spectral Energy Distributions |
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70 | (3) |
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3.3 Deriving Dust Optical Depth, Column Density, and Mass |
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73 | (2) |
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3.4 Temperature and Density Distributions |
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75 | (2) |
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3.5 Dust Energy Balance in Clouds |
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77 | (1) |
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77 | (2) |
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3.7 Dust Polarization: Origin and Measurement |
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79 | (8) |
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83 | (1) |
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84 | (3) |
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4 Simple Radiative Transfer Model |
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87 | (16) |
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87 | (1) |
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87 | (1) |
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4.3 Source Physical Conditions |
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88 | (1) |
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89 | (1) |
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4.5 Model Equation of Transfer |
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89 | (8) |
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4.6 LTE Radiative Transfer with Hydrodynamic Simulations |
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97 | (2) |
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4.7 Non-LTE Radiative Transfer with Hydrodynamic Simulations |
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99 | (4) |
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102 | (1) |
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102 | (1) |
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103 | (56) |
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5.1 Introduction: Source--Beam Coupling |
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103 | (5) |
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5.2 Quantum Electrodynamics (QED) and Maxwell |
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108 | (1) |
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5.3 Origin of a Single-Aperture Diffraction Pattern |
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109 | (4) |
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113 | (4) |
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5.4.1 Gaussian Beam Basics |
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113 | (3) |
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5.4.2 Gaussian Beam Coupling |
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116 | (1) |
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5.5 Focusing Gaussian Beams |
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117 | (18) |
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118 | (2) |
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5.5.2 Behavior of Light at Dielectric Interfaces |
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120 | (6) |
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126 | (1) |
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126 | (1) |
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127 | (3) |
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5.5.3 3 Mirror Reflective Losses and Beam Distortion |
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130 | (2) |
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5.5.4 Gaussian Beam Telescope |
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132 | (1) |
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5.5.5 Wire Grid Polarizers |
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133 | (2) |
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5.6 Intercepting Gaussian Beams |
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135 | (15) |
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5.6.1 Open-Structure Detector Optics |
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135 | (1) |
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5.6.2 Transmission-Line-Mounted Detectors |
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136 | (9) |
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5.6.3 Waveguide Feedhorns |
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145 | (1) |
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146 | (1) |
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5.6.3 2 Pickett-Potter Horn |
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147 | (1) |
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148 | (1) |
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148 | (2) |
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5.7 Illuminating THz Telescopes |
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150 | (9) |
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154 | (2) |
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156 | (3) |
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6 THz Coherent Detection Systems |
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159 | (72) |
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159 | (4) |
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6.2 Superheterodyne Receivers |
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163 | (4) |
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6.3 Receiver Noise Temperature |
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167 | (1) |
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6.4 Noise Temperature of THz Optical Systems |
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168 | (4) |
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6.5 THz Mixer Architectures and Noise |
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172 | (3) |
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6.5.1 Double Sideband (DSB) Mixer |
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172 | (1) |
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6.5.2 Sideband Separation (2SB) Mixer |
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173 | (1) |
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174 | (1) |
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175 | (4) |
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6.7 Effective Temperature Measurement of THz Components |
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179 | (3) |
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182 | (20) |
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6.8.1 Schottky Diode Mixers |
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183 | (6) |
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6.8.2 Introduction to Superconductivity |
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189 | (4) |
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6.8.3 Superconductor-Insulator-Superconductor (SIS) Mixers |
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193 | (6) |
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6.8.4 Hot Electron Bolometer (HEB) Mixers |
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199 | (3) |
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6.9 THz Local Oscillators |
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202 | (8) |
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6.9.1 Frequency Multiplied Sources |
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205 | (3) |
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6.9.2 Quantum Cascade Lasers (QCLs) |
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208 | (2) |
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210 | (10) |
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6.10.1 Total Power Detection |
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211 | (2) |
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213 | (1) |
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214 | (1) |
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6.10.2 2 Fast Fourier Transform (FFT) Spectrometer |
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215 | (1) |
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6.10.2 3 Autocorrelator Spectrometer |
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216 | (4) |
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6.11 Receiver Stability and Allan Time |
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220 | (3) |
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6.12 Heterodyne Array Considerations |
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223 | (8) |
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225 | (2) |
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227 | (4) |
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231 | (30) |
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231 | (1) |
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232 | (2) |
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7.3 Semiconductor Bolometers |
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234 | (8) |
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7.4 Superconducting Incoherent Detectors |
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242 | (8) |
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7.4.1 Transition Edge Sensors (TES) |
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242 | (3) |
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7.4.2 Microwave Kinetic Inductance Detectors (MKID) |
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245 | (5) |
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7.5 Background Noise Limited Operation |
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250 | (2) |
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7.6 Instrument Noise Limited Operation |
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252 | (1) |
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7.7 Sensitivity Requirements |
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253 | (1) |
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7.8 Comparing Heterodyne and Incoherent Detector Sensitivity |
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254 | (3) |
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7.9 Incoherent Array Considerations |
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257 | (4) |
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258 | (1) |
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259 | (2) |
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8 Terahertz Observing Techniques |
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261 | (24) |
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261 | (2) |
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263 | (4) |
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8.2.1 Absolute Position Switching |
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263 | (2) |
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265 | (1) |
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8.2.3 Frequency Switching |
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266 | (1) |
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267 | (6) |
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8.4 Estimating Atmospheric Optical Depth |
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273 | (4) |
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8.5 THz Brightness Temperature of Planetary Bodies |
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277 | (8) |
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277 | (1) |
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278 | (1) |
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8.5.3 Venus, Jupiter, Uranus, and Neptune |
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278 | (3) |
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281 | (1) |
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282 | (3) |
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285 | (24) |
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285 | (2) |
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9.2 Simple Adding Interferometer |
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287 | (5) |
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9.3 Phase Switched Interferometer |
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292 | (1) |
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9.4 Correlation Interferometer |
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293 | (2) |
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9.5 Phasor Equation for Interferometry |
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295 | (2) |
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9.6 Aperture Synthesis of Extended Sources |
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297 | (3) |
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300 | (1) |
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9.8 Transforming the Visibility Function |
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300 | (2) |
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302 | (2) |
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9.10 Phase Closure or Self-Calibration |
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304 | (1) |
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9.11 Phase Error at THz Frequencies |
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305 | (4) |
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307 | (2) |
Answers to Problems |
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309 | (4) |
Appendix 1 Timeline of THz Technology |
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313 | (2) |
Appendix 2 More THz Transitions of Atoms and Molecules |
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315 | (2) |
Appendix 3 Commonly Used Physical and Astronomical Quantities |
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317 | (2) |
Appendix 4 Useful Radiative Transfer Expressions |
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319 | (2) |
Appendix 5 Commonly Used Quasi-Optical Expressions |
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321 | (2) |
Appendix 6 Useful Heterodyne Receiver Expressions |
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323 | (2) |
Appendix 7 Dielectric Beamsplitters |
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325 | (2) |
Index |
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327 | |