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PURPOSE. To evaluate light scatter and stray light in intraocular lenses (IOLs) explanted because of postoperative opacification (13 calcified hydrophilic acrylic, 1 calcified silicone, and 4 polymethylmethacrylate [PMMA] lenses with snowflake degeneration), as well as effect of opacification on other optical quality/performance indicators, in comparison with controls. METHODS. The Complete Angle Scatter Instrument (CASI) scatterometer was used to measure the forward light scattering (FLS) of the IOLs, and the stray light values at various angles were calculated from the measured FLS. Modulation transfer function (MTF) was obtained with an optical bench, and a Badal optometer was used to obtain letter chart images through the lenses. Back light scatter and light transmittance were also measured. RESULTS. Average stray light values (Log (s)) at a scattered angle of 100 were 1.79 +/- 0.37 for hydrophilic acrylic IOLs (controls 0.36 +/- 0.05), 1.53 for the silicone lens (control 0.41), and 1.62 +/- 0.46 for PMMA IOLs (control 0.25). Stray light was significantly higher for explanted opacified lenses (N = 18) in comparison with controls (N = 7; two-tail P < 0.001 at 100). Modulation transfer function and Badal image contrast were drastically reduced in lenses with calcification and snowflake degeneration. CONCLUSIONS. Different studies described the impact of stray light in human vision, with serious hindrance above 1.47 Log (s). Lenses explanted from patients because of clinically significant opacification are associated with a considerable increase in light scatter and stray light, as well as with a decline of other optical quality/performance indicators.

by Pang Kam Moon. / Title also in Chinese characters. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 120-121). / LIST OF FIGURES --- p.iv / ACKNOWLEDGEMENTS --- p.x / ABSTRACT --- p.xi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- SPONTANEOUS BRILLOUIN SCATTERING IN MICRODROPLETS --- p.10 / Chapter 2.1 --- Outline of the theory of Spontaneous Brillouin Scattering / Chapter 2.2 --- Low-Q Spontaneous Brillouin Scattering / Chapter 2.3 --- High-Q Spontaneous Brillouin Scattering / Chapter CHAPTER 3 --- FORMULATION AND RESULTS OF STEADY STATE SBS --- p.16 / Chapter 3.1 --- SBS in Extended and Spherical Media / Chapter 3.2 --- Formulation / Chapter 3.3 --- Monochromatic Plane Wave with Definite Helicity / Chapter 3.4 --- Lorentzian Approximation to J(z) / Chapter 3.5 --- Edge Illumination / Chapter CHAPTER 4 --- TRANSIENT EFFECTS ON INTERNAL INTENSITY --- p.56 / Chapter 4.1 --- Enhancements for Internal Intensity / Chapter 4.2 --- Formulation for Transient Incident Pulse Gaussian Profile / Chapter 4.3 --- Absorption Effects / Chapter CHAPTER 5 --- TRANSIENT STIMULATED BRILLOUIN SCATTERING --- p.74 / Chapter 5.1 --- Slowly Varying Phase and Amplitude Approximation / Chapter 5.2 --- Long Temporal Gaussian Profile Incident Light / Chapter 5.3 --- Short Temporal Gaussian Profile Incident Light / Chapter CHAPTER 6 --- SBS IN MICRODROPLETS WITH ABSORPTION --- p.82 / Chapter 6.1 --- Steady State SBS with Absorption / Chapter 6.2 --- Long Temporal Gaussian Profile Incident Light / Chapter 6.3 --- Short Temporal Gaussian Profile Incident Light / Chapter 6.4 --- Singly Resonant SBS / Chapter CHAPTER 7 --- CONCLUSION --- p.98 / APPENDIX A --- p.100 / APPENDIX B --- p.102 / APPENDIX C --- p.106 / APPENDIX D --- p.108 / REFERENCES --- p.120

by Ng Chiu-king. / Title also in Chinese characters. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 189-195). / ACKNOWLEDGEMENTS --- p.v / ABSTRACT --- p.vi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- STANDARD MIE SCATTERING AND MORPHOLOGY DEPENDENT RESONANCES --- p.5 / Chapter 2.1 --- General Descriptions --- p.6 / Chapter 2.1.1 --- Nonresonant Scattering --- p.13 / Chapter 2.1.1.1 --- Internal Intensity --- p.13 / Chapter 2.1.1.2 --- Understanding in Terms of Geometric Optics --- p.14 / Chapter 2.1.2 --- Resonances --- p.19 / Chapter 2.1.2.1 --- Q-factor --- p.23 / Chapter 2.1.2.2 --- Internal Intensity --- p.25 / Chapter 2.1.2.3 --- Understanding in Terms of Geometric Optics --- p.28 / Chapter 2.2 --- Theories --- p.31 / Chapter 2.2.1 --- Nonresonances --- p.31 / Chapter 2.2.2 --- Resonances --- p.32 / Chapter 2.2.2.1 --- TE Mode in Lorentzian Form --- p.32 / Chapter 2.2.2.2 --- Degradation due to Absorption --- p.35 / Chapter 2.2.3 --- Response to a Pulse --- p.37 / Chapter 2.2.3.1 --- Nonresonant Modes --- p.38 / Chapter 2.2.3.2 --- Resonant Modes --- p.39 / Chapter CHAPTER 3 --- NONLINEAR MIE SCATTERING AND THE PROPOSED MECHANISMS --- p.42 / Chapter 3.1 --- NRL Experiment --- p.42 / Chapter 3.1.1 --- Observations --- p.42 / Chapter 3.1.2 --- Parameters --- p.43 / Chapter 3.1.3 --- Evidence of Q Degradation --- p.45 / Chapter 3.2 --- Proposed Mechanisms --- p.49 / Chapter 3.2.1 --- Volume Perturbation due to electrostrictively Generated Acoustic Waves --- p.50 / Chapter 3.2.2 --- Surface Perturbation due to Shape Distortion --- p.50 / Chapter 3.2.3 --- Stimulated Brillouin Scattering --- p.51 / Chapter 3.2.4 --- Bubbles Formation --- p.52 / Chapter 3.3 --- Envelope Fluctuation --- p.53 / Chapter CHAPTER 4 --- ELECTROSTRICTION AND THE PERTURBATION THEORY OF THE LINEWIDTH --- p.55 / Chapter 4.1 --- Electrostriction --- p.55 / Chapter 4.2 --- Perturbation of the Linewidth --- p.42 / Chapter 4.2.1 --- Theory --- p.58 / Chapter 4.2.2 --- Remarks --- p.60 / Chapter CHAPTER 5 --- ELECTROSTRICTIVELY GENERATED ACOUSTIC VIBRATIONS --- p.64 / Chapter 5.1 --- Estimate of Density Change --- p.64 / Chapter 5.2 --- Pressure Disturbances --- p.65 / Chapter 5.3 --- Electrostrictively Coupled Coefficients --- p.67 / Chapter 5.4 --- Validity of Impulse Approach --- p.70 / Chapter 5.5 --- An Expedient Model --- p.71 / Chapter 5.5.1 --- Fractional Change in Density --- p.73 / Chapter 5.5.2 --- Q Degradation --- p.81 / Chapter 5.6 --- Exact Result --- p.88 / Chapter 5.7 --- Nonimpulse Approach to Resonant Mode --- p.89 / Chapter 5.7.1 --- Results --- p.91 / Chapter 5.8 --- Chapter Conclusion --- p.93 / Chapter CHAPTER 6 --- LOW-FREQUENCY SURFACE OSCILLATIONS --- p.94 / Chapter 6.1 --- Surface Bulging --- p.95 / Chapter 6.1.1 --- Equation of Motion --- p.97 / Chapter 6.1.2 --- Results --- p.100 / Chapter 6.1.3 --- Justification of Incompressibi1ity --- p.109 / Chapter 6.2 --- Q Degradation --- p.110 / Chapter 6.2.1 --- Experimental Situation --- p.111 / Chapter 6.2.1.1 --- Single Pulse --- p.114 / Chapter 6.2.1.2 --- Pulse Train --- p.116 / Chapter 6.2.2 --- Hypothetical Bulging --- p.119 / Chapter 6.3 --- Further Investigations --- p.123 / Chapter 6.4 --- Chapter Conclusion --- p.130 / Chapter CHAPTER 7 --- STIMULATED BRILLOUIN SCATTERING --- p.131 / Chapter 7.1 --- General Descriptions --- p.132 / Chapter 7.1.1 --- Resonant SBS --- p.133 / Chapter 7.1.2 --- One Gain Mode --- p.136 / Chapter 7.2 --- SBS Pressure Disturbances --- p.137 / Chapter 7.3 --- Pulse Train --- p.140 / Chapter 7.3.1 --- Necessity of Projection --- p.141 / Chapter 7.3.2 --- Amplitude of Projected Mode --- p.143 / Chapter 7.4 --- Results --- p.145 / Chapter 7.5 --- Remarks --- p.150 / Chapter 7.6 --- Chapter Conclusion --- p.155 / Chapter CHAPTER 8 --- BUBBLE FORMATION --- p.156 / Chapter 8.1 --- Degradation due to Cavitations --- p.157 / Chapter 8.2 --- Coalescence of Gas Bubbles --- p.159 / Chapter 8.3 --- Acoustic Cavitation --- p.161 / Chapter 8.4 --- Chapter Conclusion --- p.165 / Chapter CHAPTER 9 --- CONCLUSION AND DISCUSSION --- p.166 / APPENDIX A --- p.170 / APPENDIX B --- p.175 / APPENDIX C --- p.180 / APPENDIX D --- p.184 / APPENDIX E --- p.187 / REFERENCES --- p.189

In this dissertation, I present optical emission and light scattering studies on ultraclean two-dimensional electron systems. These studies focus on emerg- ing phases in the second Landau level. I report for the excitation spectrum for fractional quantum Hall states at filling factors ν = 2+1/3, ν = 2+3/8, and ν = 2+2/5 through resonant inelastic light scattering. Resonant Rayleigh scattering is used to demonstrate that these fractional quantum Hall states are anisotropic. This work provides new insights into the nature of quasiparticle interactions of these states. It also sets the stage for the subsequent discussions about competing and coexistent phases. I present studies of emergent phases in the filling factor range 2 ≤ ν ≤ 3 using weak optical emission from the second Landau level and resonant inelas- tic light scattering by spin wave excitations. A multiplet of optical emission peaks observed that exhibit striking filling factor dependence amnifest phase competition in the second Landau level. A correlation of emission peaks in the multiplet with anomalies observed in the spin wave spectrum uncover major impact of the spin degree of freedom on the emergent phases in the second Landau level. These experiments demonstrate the promise of optical emission from excited Landau levels as a probe of emergent phases. Results from optical emission and resonant inelastic light scattering stud- ies of the second Landau level conducted at higher temperatures (T ≈ 1 K) are also presented. Evidence that many phases observed at these higher temperatures are shown to be the same as those at lower (T ≈ 40 mK) temperatures. Striking and anomalous temperature-dependence of optical emission experiments is used to gain further insight into the nature of these competing phases.

Graduation date: 1967