Optical Applications of Liquid Crystals

Contents......Page 3
1.1.1 Smectic liquid crystals......Page 15
1.1.2 Typical molecular structure......Page 16
1.1.3 Order parameters......Page 17
1.1.5 Ferroelectricity and antiferroelectricity in liquid crystals......Page 18
1.2.1 Optical properties......Page 19
1.2.2 Dielectric properties......Page 20
1.2.3 Mechanical properties......Page 21
1.3 Alignment......Page 22
1.3.1 Homogeneous, homeotropic and pretilt alignment......Page 23
1.3.3 Chevron formation in tilted smectics......Page 24
1.3.4 Influence of pretilt......Page 26
1.3.5 Zig-zag formation......Page 27
1.3.6 Surface stabilization......Page 28
1.4.2 Optical properties of chevron structures without pretilt......Page 29
1.4.4 Optical properties of antiferroelectric liquid crystal structures......Page 30
1.5.1 SmA* field response......Page 31
1.5.2.1 Simple bookshelf surface-stabilized ferroelectric liquid crystal device......Page 32
1.5.2.2 Effect of the chevron structure in SSFLCs......Page 34
1.5.3 Distorted helix effect......Page 36
1.5.4 Twisted SmC* effect......Page 37
1.5.5.1 Pretransitional effect......Page 38
1.5.5.3 Surface stabilized devices......Page 39
1.5.5.4 Hysteretic and thresholdless switching......Page 40
1.6.1 Typical modes of operation......Page 41
1.6.2.1 Spatial dithering......Page 43
1.6.3 Display addressing schemes......Page 44
1.7.1.1 Electrically addressed SLM......Page 45
1.7.1.2 Optically addressed SLM......Page 47
1.7.1.3 Basic SLM applications......Page 49
1.7.2.1 2 x 2 fibre optic switch using FLC polarization switches......Page 50
1.7.2.2 1 x N holographic optical switching......Page 52
1.7.2.3 N x N holographic optical switching......Page 55
1.7.2.4 Fabry-Perot type continuous tunable filters......Page 56
1.7.2.5 Digitally tunable optical filters......Page 59
1.7.2.6 FLC-based optical waveguides, switches and modulators......Page 61
1.7.3 Optical data processing applications......Page 64
1.7.3.1 Optical parallel processing of binary images......Page 65
1.7.3.2 Optical correlation......Page 66
1.7.4.1 Photonic delay lines for phased-array antenna systems......Page 69
1.7.4.2 Dynamic arbitrary wavefront generation......Page 70
References......Page 72
2.1 Electro holography......Page 76
2.1.1 The basics of holography......Page 77
2.1.2.1 Optical characteristics of liquid crystals......Page 78
2.1.2.2 Matrix pixel driving......Page 83
2.1.2.3 Liquid crystal spatial light modulator using MIM devices......Page 86
2.1.3 Electro holography using a liquid crystal TV spatial light modulator......Page 89
2.1.3.1 Recording optics and reconstructing optics......Page 90
2.1.3.2 Reconstructed image and its characteristics......Page 93
2.2.1.1 The basics of diffraction......Page 99
2.2.1.2 Liquid crystal diffractive optics......Page 102
2.2.1.3 Liquid crystal refractive optics......Page 106
2.2.2 Application to optical pickup......Page 110
2.2.2.1 Optical equalizer......Page 112
2.2.2.2 Coma aberration corrector......Page 119
2.2.2.3 Spherical aberration corrector......Page 124
References......Page 129
3.1 Introduction......Page 132
3.2 Adaptive optics: definition and history......Page 134
3.3 Image formation: basic principles......Page 137
3.4 The effect of aberrations......Page 140
3.5 Active and adaptive optics......Page 142
3.6.1 Liquid crystal correctors......Page 144
3.6.2 What kinds of LC are of interest?......Page 147
3.7.1 Viscosity and elastic constant......Page 149
3.7.3 Control voltage......Page 150
3.7.6 Pulse method......Page 152
3.8 Wavefront sensing techniques......Page 153
3.8.1 Shack-Hartmann wavefront sensor......Page 154
3.8.2 Phase diversity (curvature sensing)......Page 156
3.8.3 Putting it all together......Page 157
References......Page 160
4.1 Introduction......Page 162
4.2 PDLC preparation techniques......Page 165
4.2.1 General preparation techniques......Page 169
4.2.1.1 Emulsion technique......Page 170
4.2.1.3 Polymerization-induced phase separation (PIPS)......Page 171
4.2.1.5 Solvent-induced phase separation (SIPS)......Page 172
4.2.2.4 Phase modulation......Page 173
4.3 The physics involved in PDLCs......Page 174
4.3.1.1 The order parameter......Page 175
4.3.1.2 The free energy density......Page 178
4.3.2.1 Single scatterer......Page 180
4.3.2.2 A slab of scatterers......Page 184
4.4.1 Droplet configurations......Page 186
4.4.1.1 Analytical/numerical approach......Page 187
4.4.1.2 Computer simulation approach......Page 188
4.4.1.3 Multiple-order parameters approach......Page 190
4.4.2.1 Anomalous diffraction approach......Page 192
4.4.2.2 Rayleigh-Gans approximation......Page 194
4.4.2.3 Multiple-order parameters approach......Page 195
4.5.1 Smart windows......Page 196
4.5.2 Heat-resistant PDLC light modulator......Page 198
4.5.3 Spatial light modulators......Page 199
4.5.4 Direct-view displays......Page 202
4.5.5 Projection displays......Page 203
4.5.6 Eye-protection viewer......Page 205
4.5.7 Sensors......Page 206
4.5.8 Holographic PDLCs......Page 207
4.5.9 Scattering polarizers......Page 208
References......Page 210
5.1 Introduction......Page 215
5.2 Mechanisms of LC photo-alignment......Page 216
5.2.1.1 Command surface......Page 217
5.2.1.2 Cis-trans transformations in azo-dye side chain polymers and azo-dye in polymer matrix......Page 218
5.2.2 Pure reorientation of the azo-dye chromophore molecules or azo-dye molecular solvates......Page 219
5.2.3 Crosslinking in cinnamoyl side-chain polymers......Page 223
5.2.4 Photodegradation in polyimide materials......Page 224
5.3.1 Improvement of materials for photo-aligning......Page 228
5.3.2 Pretilt angle generation in photo-aligning materials......Page 229
5.3.3 Anchoring energy in photo-aligning materials......Page 233
5.4.1 Multi-domain LC cells......Page 235
5.4.2 Photo-patterned phase retarders and colour filters......Page 237
5.4.3 Photo-patterned polarizers......Page 242
5.4.4 Security applications......Page 247
5.5.1 Photo-aligning of ferroelectric LC......Page 250
5.5.2 Photo-aligning of vertical aligned nematic (VAN) mode......Page 251
5.5.3 Photo-aligning of discotic LCs......Page 252
5.6 Conclusions......Page 253
References......Page 254
6.1 Practical spatial modulation......Page 259
6.2.1 Passive matrix addressing......Page 260
6.2.1.1 Multiplexing addressing......Page 261
6.2.2.1 TFT active matrix......Page 262
6.2.2.2 LCOS and Si-based matrix......Page 265
6.2.2.4 Alternating field driving......Page 266
6.2.2.6 Longitudinal and lateral field effect......Page 269
6.2.3.2 Photoconductor addressing......Page 270
6.2.4.2 Plasma addressing......Page 272
6.3.1 Twisted nematic (TN) mode......Page 273
6.4 Phase modulation and applications......Page 274
6.4.1 Active matrix phase modulator......Page 275
6.4.1.2 Phase modulation characteristics......Page 276
6.4.2.2 Interference and diffraction effects......Page 277
6.4.3 Spatial wavefront modulator (SWM)......Page 279
6.5.1 PDLC......Page 281
6.5.2.1 Scattering and Schlieren optics......Page 283
References......Page 284