This volume contains key papers that document the initial probing of the limits of subnanosecond pulses and the resulting discoveries of nonlinear effects. The papers tell the story of effects previously thought to be impossible to produce in tissue. If you read all the references carefully, you will see the studies evolve from speculation to experimentation to theory, and culminate in policy recommendations.
Applications of ultrashort pulse laser systems have increased dramatically in the past several years. Retinal exposure to these laser pulses can produce visible lesions with pulse energies of less than 1 microjoule (microJ) per pulse. Our research has found a reduction in the energy required for retinal damage as pulse duration is decreased from the nanosecond (ns) to femtosecond (fs) regime. With this data, new laser safety standards are being proposed to reduce the dangers and uncertainties when working around these lasers.
A collection of papers dealing with the colour-center laser. The first section deals with fundamental research that preceded the colour-center laser, the second covers the discovery and development of several types of laser and the final section contains examples of applications of the laser.
Keratoplasty is the transplantation of all or part of the cornea to repair scarred or damaged tissue. A femtosecond laser is a laser which emits ultrashort pulses, used for minimally invasive corneal surgery. This book is a concise guide to the technique of femtosecond laser-assisted keratoplasty. Beginning with an introduction to the technology, the following chapters discuss its use for different disorders. This practical text is based on the surgical experience of its internationally recognised authors from Spain, Germany, France and the USA. It includes more than 230 full colour clinical photographs and illustrations to enhance learning. Key points Concise guide to the corneal transplantation procedure of femtosecond laser-assisted keratoplasty Covers key technologies and uses for different disorders Internationally recognised author and editor team Includes more than 230 clinical photographs and illustrations
Ten years ago, Stanley L. Shapiro edited the book entitled Ultrashort Light Pulses (Topics Appl. Phys., Vol. 18), which was written by eight experts in the field. Six years later, Charles V. Shank added a bibliography (1980-1983) in the second edition with approximately one thousand new references. During the past decade the field has grown so rapidly that a completely new book had to be written. In particular, the reduction of the time scale of light pulses into the femtosecond range has opened up new experimental possibilities never even foreseen in the preceding literature. The vast literature with countless ideas and applications makes it impossible for a single person to write a comprehensive review. Nine scientists, actively working in the field since its beginning, have decided to join forces to prepare a new book describing the present state of the art. Emphasis is placed on the generation and numerous applications of ultrashort laser pulses. This book covers a wide area of science: physics, engineering, chemistry, and biology. The various chapters and sections are prepared in each case such that the reader is given a brief introduction to the specific subject. Ample references for a more detailed study are given at the end of each chapter.
Keratoplasty techniques have evolved in the last 15 years into a variety of forms, which have diversified the previous monographic presence of the penetrating keratoplasty technique. The development of anterior lamellar graft (DALK), and posterior lamellar graft (DSAEK), makes an important change in the approach to lamellar surgery. Later on, the appearance of DMEK and superficial lamellar keratectomy broadened the spectrum. Today, intralamellar surgery has evolved with a number of techniques that involve stromal enhancement with biologically active or acellular corneal laminas from donors, customized lenticles from SMILE surgeries or customized by corneal topography, and more recently, corneal regeneration of the stroma by advanced techniques using mesenchymal stem cells. This book offers a comprehensive overview of modern keratoplasty techniques, the technology, surgical skills, and outcomes. It highlights the practical uses of keratoplasty for all cornea surgeons and anterior segment surgeons. The book is divided into sections, each covering a specific type of keratoplasty, including chapters on innovations within each surgery type. The goal of this book is to unify all recent knowledge about the different keratoplasty techniques and outcomes, creating a one-stop resource for ophthalmaolgy surgeons. Modern Keratoplasty is a must-have resource for corneal specialists and surgeons, anterior segment surgeons, refractive surgeons, cataract surgeons, residents, fellows, and corneal researchers.
The original goal of this project was to determine the role of non-linear interactions underlying the bioeffects induced by ultrashort pulse laser pulses. As initially conceived, this line of investigation was to be principally directed at understanding the contribution of multiphoton absorption. This indeed was a major focus of the research project, but for various reasons the scope of the work was expanded to include identification of the intracellular mechanisms that determine the cellular response to the absorption of optical radiation, and to develop and implement a non-invasive means for measuring the thermal gradients induced by the absorption of laser radiation in tissue. Both of these ancillary projects were successful in that (1) the transcription factor NF-B was found to be activated by visible laser exposure in a way that appeared to be dependent on the absorption of laser energy in the melanin granules of the retinal pigment epithelial cell, and (2) by exploiting the temperature-dependent nature of the proton resonance frequency (PRF), magnetic resonance thermography was successfully used to measure temperature gradients induced in tissue phantoms during laser exposure, and these gradients closely followed the spatial distributions predicted by classical heat diffusion theory.
The use of laser light for targeting devices and weapons has sharply increased the likelihood that aircrew and support personnel will be exposed to laser light during operations. The increased potential for exposure of humans highlights the fact that there is a need for scientifically based safety standards for laser exposure at the ultrashort pulse lengths. Current safety standards are largely extrapolations of exposure limits at longer pulse lengths using a minimal visible lesion endpoint in the Rhesus monkey retinal model. A non-animal model for assessing laser-light damage to tissue, particularly human, is quite desirous for obvious scientific, political, and fiduciary reasons. I assessed the sublethal insult to human cells using a tissue culture system for specific genes that have been shown to be important in several biological processes that could lead to cancer or cell death. Using the CAT-Tox (L) (xenometrix, Inc.) assay, it appears that 532 nm nanosecond pulse of laser light are sensed and induces several stress response genes including FOS in a roughly dose dependent fashion. This approach provides insight into a more global methodology for characterizing environmental stressors via genetic profiling.
This authoritative book is written by ten experts in the field. It provides an up-to-date review of the state of the art in different generation processes for ultrashort laser pulses. Extensive applications in a wide range of fields - in physics, engineering, chemistry, and biology - are also discussed. Eight chapters deal with the following topics: - the generation of picosecond and femtosecond laser pulses - nonlinear wave interactions - new investigations in solid-state physics - recent progress in optoelectronics - advances in coherent material excitations - ultrafast vibrational lifetimes and energy redistribution in liquids - new observations of chemical reactions in the liquid state - the primary processes of important biological systems The book is essential reading for scientists and engineers who want to know what is going on in this rapidly advancing field. It should also interest graduate students and others who seek an introduction to laser pulses.
