"Nonlinear optical biomedical imaging techniques have attracted a great amount of interest starting with the first demonstration of two-photon fluorescence (TPF) imaging by Webb's group in the 1990s. The various imaging formats and applications reported have revolutionized the field of biomedical imaging, offering great advantages including high resolution, internal three-dimensional sectioning ability, and functional imaging capability. This thesis focuses on exploring the development and novel application of nonlinear optical techniques and extending previous work in transmission mode nonlinear absorption imaging. The topical pharmacological introduction of molecules and drugs to the ocular surface is a common means of assessing and treating a variety of pathological ocular conditions. However, no reliable method exists to date for the quantification of actual delivered dosage with high enough resolution. We developed a two-photon fluorescence (TPF) system capable of quantifying, with micron-level axial resolution, the distribution and concentration of fluorescent or fluorescently-tagged chemicals and drugs in live feline corneas. With this high-resolution method, we were able to measure, for the first time, both the penetration depth and concentrations of molecules applied topically to the ocular surface, either with an intact or removed epithelial layer. As a proof of concept, we tested two classes of fluorescent molecules- Fluorescein and Riboflavin- which are commonly used in ophthalmologic practice. Finally, we used our TPF instrument to test the barrier function of the corneal epithelium and to measure the concentration of non-fluorescent molecules (in this case, dextrans) conjugated to fluorescent dyes as they diffused across the cornea. A pump-probe based technique has been applied in biomedical imaging by Prof. Warren Warren's group recently. They reported images with endogenous contrast agents (hemoglobin and melanin) in biological tissue in a transmission mode with two pulsed laser systems to generate two wavelengths for the pump and probe beam. We built two simplified systems with only one Ti:Sapphire laser. In both systems, the pump and probe beam were selected from a broadband source, which was generated by either broadening the spectrum with a holey fiber or a 27 fs KM laser, which has a broad spectrum itself. We explored the capability of imaging in tissue-like turbid media in the backscattering mode, and studied the achievable imaging depth for the first time. By simulating using Monte Carlo based methods, we further optimized the detection geometry and improved the photon collection efficiency. Also, we compared this nonlinear absorption technique with the more commonly used TPF method. We finally obtained pump probe signals and images using quantum dots as a nonlinear medium. This could be important in future studies of toxicity in skin-care products"--Leaves vi-vii

"Nonlinear optical biomedical imaging techniques have attracted a great amount of interest starting with the first demonstration of two-photon fluorescence (TPF) imaging by Webb's group in the 1990s. The various imaging formats and applications reported have revolutionized the field of biomedical imaging, offering great advantages including high resolution, internal three-dimensional sectioning ability, and functional imaging capability. This thesis focuses on exploring the development and novel application of nonlinear optical techniques and extending previous work in transmission mode nonlinear absorption imaging. The topical pharmacological introduction of molecules and drugs to the ocular surface is a common means of assessing and treating a variety of pathological ocular conditions. However, no reliable method exists to date for the quantification of actual delivered dosage with high enough resolution. We developed a two-photon fluorescence (TPF) system capable of quantifying, with micron-level axial resolution, the distribution and concentration of fluorescent or fluorescently-tagged chemicals and drugs in live feline corneas. With this high-resolution method, we were able to measure, for the first time, both the penetration depth and concentrations of molecules applied topically to the ocular surface, either with an intact or removed epithelial layer. As a proof of concept, we tested two classes of fluorescent molecules- Fluorescein and Riboflavin- which are commonly used in ophthalmologic practice. Finally, we used our TPF instrument to test the barrier function of the corneal epithelium and to measure the concentration of non-fluorescent molecules (in this case, dextrans) conjugated to fluorescent dyes as they diffused across the cornea. A pump-probe based technique has been applied in biomedical imaging by Prof. Warren Warren's group recently. They reported images with endogenous contrast agents (hemoglobin and melanin) in biological tissue in a transmission mode with two pulsed laser systems to generate two wavelengths for the pump and probe beam. We built two simplified systems with only one Ti:Sapphire laser. In both systems, the pump and probe beam were selected from a broadband source, which was generated by either broadening the spectrum with a holey fiber or a 27 fs KM laser, which has a broad spectrum itself. We explored the capability of imaging in tissue-like turbid media in the backscattering mode, and studied the achievable imaging depth for the first time. By simulating using Monte Carlo based methods, we further optimized the detection geometry and improved the photon collection efficiency. Also, we compared this nonlinear absorption technique with the more commonly used TPF method. We finally obtained pump probe signals and images using quantum dots as a nonlinear medium. This could be important in future studies of toxicity in skin-care products"--Leaves vi-vii.

The use of light for probing and imaging biomedical media is promising for the development of safe, noninvasive, and inexpensive clinical imaging modalities with diagnostic ability. The advent of ultrafast lasers has enabled applications of nonlinear optical processes, which allow deeper imaging in biological tissues with higher spatial resolution. This book provides an overview of emerging novel optical imaging techniques, Gaussian beam optics, light scattering, nonlinear optics, and nonlinear optical tomography of tissues and cells. It consists of pioneering works that employ different linear and nonlinear optical imaging techniques for deep tissue imaging, including the new applications of single- and multiphoton excitation fluorescence, Raman scattering, resonance Raman spectroscopy, second harmonic generation, stimulated Raman scattering gain and loss, coherent anti-Stokes Raman spectroscopy, and near-infrared and mid-infrared supercontinuum spectroscopy. The book is a comprehensive reference of emerging deep tissue imaging techniques for researchers and students working in various disciplines.

In this thesis we demonstrate novel methods to overcome optical scattering in order to resolve information about hidden scenes, in particular for biomedical applications. Imaging through scattering media has long been a challenge, as scattering corrupts scenes in a non-invertible way. The use of near-visible optical spectrum for biomedical purposes has many advantages, such as optical contrast, optical resolution and nonionizing radiation. Particularly, it has important applications in biomedical imaging, such as sub-dermal imaging for diagnostics, screening and monitoring conditions. We demonstrate methods to overcome and use scattering in order to recover scene parameters. In particular we demonstrate a method for locating and classifying fluorescent markers hidden behind turbid layers using ultrafast time-resolved measurements with a sparse-based optimization framework. This novel method has applications in remote sensing and in-vivo fluorescence lifetime imaging. Another method is demonstrated to resolve blood flow speed within skin tissue. This method is based on a computational photography technique and coherent illumination. This method can be applied in diagnosis and monitoring of burns, wounds, prostheses and cosmetics. A particularly important application of this technology is analysis of diabetic ulcers, which is the main cause for non-traumatic amputations in India. The suggested prototype is suitable for assisting clinicians in assessing the wound healing process. The methods developed in this thesis using ultrafast time-resolved measurements, sparsity-based optimization and computational photography can spur research and applications in biomedical imaging, skin conditions diagnosis and more general modalities of imaging through scattering media.

This handbook provides a comprehensive review of the entire field of laser micro and nano processing, including not only a detailed introduction to individual laser processing techniques but also the fundamentals of laser-matter interaction and lasers, optics, equipment, diagnostics, as well as monitoring and measurement techniques for laser processing. Consisting of 11 sections, each composed of 4 to 6 chapters written by leading experts in the relevant field. Each main part of the handbook is supervised by its own part editor(s) so that high-quality content as well as completeness are assured. The book provides essential scientific and technical information to researchers and engineers already working in the field as well as students and young scientists planning to work in the area in the future. Lasers found application in materials processing practically since their invention in 1960, and are currently used widely in manufacturing. The main driving force behind this fact is that the lasers can provide unique solutions in material processing with high quality, high efficiency, high flexibility, high resolution, versatility and low environmental load. Macro-processing based on thermal process using infrared lasers such as CO2 lasers has been the mainstream in the early stages, while research and development of micro- and nano-processing are becoming increasingly more active as short wavelength and/or short pulse width lasers have been developed. In particular, recent advances in ultrafast lasers have opened up a new avenue to laser material processing due to the capabilities of ultrahigh precision micro- and nanofabrication of diverse materials. This handbook is the first book covering the basics, the state-of-the-art and important applications of the dynamic and rapidly expanding discipline of laser micro- and nanoengineering. This comprehensive source makes readers familiar with a broad spectrum of approaches to solve all relevant problems in science and technology. This handbook is the ultimate desk reference for all people working in the field.

The objective of the research program was to investigate nonlinear optical phenomena and optical amplification and lasing in highly scattering active and non-active random media. The aim of research was to develop a deeper fundamental understanding of light propagation in active random media for future generation of optical display, imaging techniques and laser devices. Two photon excited fluorescence and second harmonic generation tomographic imaging of biomedical tissues were demonstrated. Lasing and optical amplification from dyed active turbid media and biological tissues were explored. A feedback mechanism from scattering walls was proposed to describe lasing characteristics in random media. We have published 12 papers and submitted two patent applications.

One of the first books devoted entirely to the subject of Raman microscopy, Raman Microscopy addresses issues of great interest to engineers working in Raman-microscope development and researchers concerned with areas ofapplication for this science. The book is written by several world recognized experts, who summarize the Raman effect before discussing the hardware and software involved in todays instruments. This format provides an excellent introduction to this up-and-coming discipline. All important applications, including those in materials science and earth science are covered in depth. - Includes extensive description of the instrumentation, the Raman microspectrograph, the treatment of data, and micro-Raman imaging - Examines the use of Raman microscopy in diverse applications, including some of the hyphenated methods - Summarizes the Raman effect - Discusses new uses for this technology