Progress in Optics (eBook)

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2010 | 1. Auflage
408 Seiten
Elsevier Science (Verlag)
978-0-444-53706-5 (ISBN)

Infos

In the 50 years since the first volume of Progress in Optics was published, optics has become one of the most dynamic fields of science. The volumes in this series that have appeared up to now contain more than 300 review articles by distinguished research workers, which have become permanent records for many important developments. - Invariant Optical Fields - Quantum Optics in Structured Media - Polarization and Coherence Optics - Optical Quantum Computation - Photonic Crystals - Lase Beam-Splitting Gratings

Inhalt

Front Cover 1
Progress in Optics 4
Copyright 5
Table of Contents 6
Preface 10
Chapter 1. Optical Pulse Propagation in Biological Media: Theory and Numerical Methods 12
1. Introduction 12
2. Light Scattering 15
3. Photon Transport Equation 19
4. Numerical Methods 29
5. Concluding Remarks 44
References 45
Chapter 2. Manipulating Light Statesby Single-Photon Addition and Subtraction 52
1. Introduction 53
2. Single-Photon Operators for Manipulating Quantum Information 54
3. Single-Photon Addition 59
4. Single-Photon Subtraction 72
5. Sequences and Superpositions of Single-Photon Operators 83
6. Conclusions 87
7. Acknowledgments 88
A. Quantum Tomography 88
References 90
Chapter 3. Vacuum-Induced Processes in Multilevel Atoms 96
1. Introduction 97
2. Mathematical Model 98
3. Single-Particle Processes 122
4. Collective Processes 161
Acknowledgments 194
References 195
Chapter 4. Adaptive Lens 210
1. Introduction 211
2. Adaptive Liquid Crystal Lens 214
3. Adaptive Liquid Lens 269
4. Examples of Applications of the Adaptive Lenses 285
5. Conclusion 289
Acknowledgments 289
References 289
Chapter 5. The Structure of Partially Coherent Fields 296
1. Preface 296
2. The Space-Frequency Representation 298
3. Partially Coherent Fields in Young's Experiment 302
4. The Evolution of Partially Coherent Beams 307
5. Focusing of Partially Coherent Wave Fields 313
6. Scattering of Partially Coherent Wave Fields by Random and Deterministic Media 319
7. Phase Singularities of Coherence Functions 325
8. The Coherent Mode Representation 331
9. Numerical Simulation of Partially Coherent Fields 335
10. Direct Applications of Coherence Theory 337
References 340
Author Index for Volume 55 354
Subject Index for Volume 55 370
Contents of Previous Volumes 378
Cumulative Index – Volumes 1–55 392

Textauszug

Chapter 1

Optical Pulse Propagation in Biological Media: Theory and Numerical Methods

Malin Premaratne [e-mail] Advanced Computing and Simulation Laboratory (AχL), Department of Electrical and Computer Systems Engineering, Monash University, Clayton, Victoria, Australia.

Publisher Summary

Different versions of the “Tricorder” device used in Star-Trek science fiction series can noninvasively scan any physical, chemical, or biological entity and cure ailments by hovering over their bodies. Recent advances in ultra-sound and electromagnetics (including optics) could make “Tricorder” a reality. Increasingly, novel innovative ways of using light for clinical applications are developed by researchers all around the world. All these developments rely on having a detailed understanding of light propagation through tissue. Such understanding can only be gained by creating sufficiently accurate models that can capture the essence of light interaction with biological media. This chapter covers the transient characteristics of optical fields propagating through biological media at sufficiently low power levels, which do not induce physical or chemical changes in the material. It specifically looks at short, low-intensity pulses interacting with biological media and discards any light-induced permanent changes (tissue damage and ablation) or secondary emission processes (fluorescence and phosphorescence). A review of the basic features of light scattering from biological media is presented that points out some specific features and provides pointers to literature for specific details. The quantitative aspects of light propagation through tissue are covered by a discussion of the general structure of the transient photon transport equation and related quantities. Various ways of solving the transient photon transport equation is described and the strengths and weakness of each method is highlighted.

1 INTRODUCTION

Science fiction captures the imagination of human mind and inspires us to make the dreams of today a reality tomorrow. Different versions of the “Tricorder” device used in Star-Trek science fiction series can noninvasively scan any physical, chemical, or biological entity and cure ailments by hovering over their bodies (Figure 1). Recent advances in ultrasound and electromagnetics (including optics) could make “Tricorder” a reality. Increasingly, novel innovative ways of using light for clinical applications are developed by researchers all around the world (Wilson, Tuchin, & Tanev, 2005. For example, optical probes capable of carrying out tissue diagnosis offer significant advantages over standard biopsy and cytology techniques, in terms of both patient care and medical costs (Mourant et al., 1998). These probes have the capability to detect cancerous tissues because the interaction of light with tissue is strongly influenced by the composition and the cellular structure of tissue, which is obviously different for cancerous and healthy tissues (Wilson et al., 2005). Similarly, photodynamic therapy is increasingly used as a replacement or alternative way of treating cancerous cells with minimal side effects (Gobin et al., 2007; Prasad, 2003). Photodynamic therapy is the use of drugs (photosensitizers) that are activated by visible or near infrared light to produce specific biological effects in cells or tissues that can be exploited to achieve a particular clinical endpoint (Wilson et al., 2005). Recently, nanoshells have also been used as the activating medium (Gobin et al., 2007). When photosensitive dyes are used, cancerous cells are killed by injecting them in the vicinity of the cancerous cells and then transferring them to a toxic state using laser light (Niemz, 2004). In case of nanoshells, the heat generated by the nanoshells irradiated with resonant laser light causes the destruction of cancerous cells (Gobin et al., 2007). Laser-induced interstitial thermotherapy (LITT) is another technique used for tumor treatment, which makes use of the possibility of localized tissue coagulation (Niemz, 2004). LITT was recently introduced to treat tumors in retina, brain, prostate, liver, and uterus (Niemz, 2004). Lasers are also being used for diagnostic and therapeutic purposes in ophthalmology, where the conventional incoherent light sources fail. For example, retinal glaucoma and retinal detachment can be accurately assessed and diagnosed by using confocal laser microscopy (Niemz, 2004).

Figure 1 Usage of Starfleet Tricorder in Star-Trek series © Paramount Pictures and CBS Studios.

All these developments relies on having a detailed understanding of light propagation through tissue. Such understanding can only be gained by creating sufficiently accurate models that can capture the essence of light interaction with biological media. Experiments are a vital part of this model-making process where they provide a solid basis and sound understanding necessary to conceptualize the fundamental ideas/axioms central to a model. Good models enable one to make predictions beyond their initial experimental base and discover novel phenomena. For engineers, these models eventually provide a way to optimize and fine tune techniques/devices that would have not been possible in other means. For example, heat is generated due to the interaction with light and tissue. The resulting local tissue temperature is of prime importance in laser surgery and depends, in turn, on the spatial distribution of the incident radiation. A detailed modeling is required to determine the duration of the laser light exposure of tissue for a successful surgical outcome. Errors cannot be tolerated in such clinical settings where the outcome might decide the fate of a patient undergoing laser surgery! Moreover, the development of diagnostic techniques such as optical coherence tomography, confocal microscopy, light scattering spectroscopy, and optical reflectance microscopy requires a fundamental understanding of how light scatters from normal and pathological structures within tissue (Wilson et al., 2005). In addition to these, lasers are used in ophthalmology, gynecology, urology, and many other fields (Huang et al., 1991; Niemz, 2004; Webb, 1996). Therefore, it is important to understand the effects of various optical parameters (i.e., model parameters) and their effect on the incident and scattered light to interpret these measurements appropriately (Mourant et al., 1998).

Increasingly, it has become clear that much can be learned about biological media by using temporal optical interactions. Most importantly, different cross-talk problems (i.e., interfering signals) arising in the steady-state optical interactions with biological media can be mitigated using properly executed temporal probing techniques (Tuchin, 2007; Welch & van Gemert, 1995). For example, short light pulses can be used to enhance image resolution in optical tomography techniques as cleverly exploited in the time-resolved spectroscopy area (Arridge, 1999). Another area of importance is optical coherence tomography (OCT), which uses low-coherence interferometry to produce a two-dimensional image of optical scattering from internal tissue microstructures in a way that is analogous to ultrasonic pulse-echo imaging (Huang et al., 1991). Both low-coherence light and ultrashort laser pulses can be used to map internal structures of biological systems. An optical signal that is transmitted through or reflected from a biological tissue will contain time-of-flight information, which in turn yields spatial information about tissue microstructure (Huang et al., 1991).

Given the many facets of recent advances in biology and optics, and the pace and overdrive of the innovation, it is a formidable or even an impossible task to map the current state of these technologies in a single snapshot. Many articles have comprehensively covered the trends and techniques in static optical fields interacting with biological media (Peraiah, 2002; Pomraning, 2005; Welch & van Gemert, 1995). Therefore, our primary aim is to cover the transient characteristics of optical fields propagating through biological media at sufficiently low power levels, which do not induce physical or chemical changes in the material. We specifically look at short, low-intensity pulses interacting with biological media and discard any light-induced permanent changes (e.g., tissue damage and ablation) or secondary emission processes (e.g., fluorescence and phosphorescence). This review is organized as follows: In the Section 2, we review the basic features of light scattering from biological media. We point out some specific features and provide pointers to literature for specific details. In Section 3, we look at the quantitative aspects of light propagation through tissue by discussing the general structure of the transient photon transport equation and related quantities. One major component of the photon transport equations is the scattering phase function, which takes care of the details of specific features of the scattering objects. We provide a catalog of many known phase functions and highlight their features, so reader can make an informed decision when selecting a phase function for analysis of biological media. We specifically point out the fact that further research needs to be done in coming up with better phase functions for biological media. Section 4 shows various ways of...

Produkt-Details

• Erscheint lt. Verlag: 15.12.2010
• Mitarbeit: Herausgeber (Serie): Emil Wolf
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Physik / Astronomie ► Optik
• Themenwelt: Technik
• ISBN-10: 0-444-53706-6 / 0444537066
• ISBN-13: 978-0-444-53706-5 / 9780444537065