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The diversity of the chapters presented in this volume illustrates not only the many applications of lasers, but also the fact that, in many cases, these are not new uses of lasers, but rather improvements of laser techniques already widely accepted in both research and clinical situations. Biological reactions to some special aspects of laser exposure continue to show new effects, which have implications for the ever-present topic of laser safety. Such biological reactions are included in fields of research which depend on properties of electromagnetic radiation exposure only possible with lasers, for example, the short pulses necessary for the temperature-jump experiments reviewed by Reiss: Speciality lasers, such as the transverse excitation atmospheric (TEA) or excimer lasers, add new wavelengths and pulse domains to those already available for biological application. A description of these new types of lasers by Osgood is included to indicate new possibilities for future use and to avoid limiting our coverage to well-developed present-day applications. Hillenkamp and Kaufmann describe a microprobe mass spectrograph for analysis of the minute amounts of material evaporated by a laser pulse. The analytical possibilities of this instrument are far-reaching, and some of the various results are described to illustrate the power of their method, as well as to show the types of problems that are suitable for it. The initial steps in photosynthesis have become the subject of intensive investigation.

Laser Applications in Medicine and Biology: Volume 4

1 The Laser as a Tool in the Study of Photosynthesis.- 1. Introduction.- 2. Technical Aspects of the Laser Research Methods Used in Photosynthetic Research.- 2.1. The Sources of Short and Ultrashort Pulses.- 2.1.1. Q-Switched Lasers.- 2.1.2. Mode-Locked Lasers.- 2.1.3. Frequency Tuning.- 2.2. Picosecond Spectrometers for the Absorbance Change Measurements.- 2.2.1. Echelon Method.- 2.2.2. Optical Delay Line Method.- 2.3. Picosecond Fluorometry.- 2.3.1. Optical Kerr Gate Method.- 2.3.2. Streak Camera Techniques.- 2.3.3. Photon Counting Fluorometry.- 2.3.4. Frequency Mixing in Nonlinear Crystals.- 2.4. Raman Spectroscopy.- 2.5. Laser Monitoring Techniques.- 3. Laser Studies of Photosynthesis.- 3.1. The Primary Events.- 3.1.1. Energy Migration.- 3.1.2. Charge Separation and Stabilization.- 3.2. Photosynthesizing Bacteria.- 3.3. Higher Plants.- 3.4. Molecular Organization of the Photosynthetic Apparatus.- 3.4.1. Action of Ruby Laser Radiation.- 3.4.2. Raman Scattering Spectroscopy.- 4. Conclusion.- References.- 2 Requirements and Technical Concepts of Biomedical Microprobe Analysis.- 1. Prologue.- 1.1. Introduction.- 2. Actual Microprobe Instruments.- 2.1. Electron Probe X-Ray Microanalysis (EPXM).- 2.2. Ion Microprobe.- 2.3. Raman Scattering Microprobes.- 2.4. Laser Microprobe Emission Spectroscopy.- 2.5. Laser Microprobe Mass Analysis (LAMMA).- 3. The LAMMA Instrument and Its Performance.- 3.1. General Concept.- 3.2. Laser and Laser Optics.- 3.3. The TOF Spectrometer and Signal Detection.- 3.4. Sensitivity.- 3.5. Quantitative Analysis.- 4. LAMMA Applications in Biomedical Microprobe Analysis.- 4.1. Specimen Preparation for LAMMA Analysis.- 4.2. Distribution of Physiological Cations and Trace Elements in Soft Biological Tissues.- 4.3. K/Na Ratio in Transport Active Epithelia of the Inner Ear (Stria Vascularis).- 4.4. K/Na/Ca Ratio in Single Isolated Skeletal Muscle Fibers.- 4.5. Fe/Mg Ratio in Single Human Red Blood Cells.- 4.6. Detection and Localization of Trace Elements in Biological Tissues.- 5. LAMMA Applications in Particle Analysis.- 5.1. Microanalysis of Small Particles: Some General Considerations.- 5.2. Performance and Limitations of the LAMMA Technique as Applied to Particle Research.- 5.3. LAMMA Analysis of Reference Particles.- 5.4. LAMMA Analysis of True Aerosols.- 5.5. LAMMA Analysis of Asbestos and Man-Made Mineral Fibers.- 6. LAMMA Applications in Organic Mass Spectrometry.- 6.1. Mass Spectroscopy of Nonvolatile or Thermally Labile Compounds.- 6.2. Laser Desorption Mass Spectrometry.- 6.3. Laser Pyrolysis.- 6.4. Laser Desorption Spectra of Amino Acids and Peptides.- 6.5. LAMMA Investigation of Human Skin.- 6.6. Mass Spectrometric Fingerprinting of Mycobacteria.- 7. Conclusions and Outlook.- References.- 3 Ultrashort Laser Pulses in Biomedical Research.- 1. Introduction.- 1.1. Study of Fast Biological Events May Require Particular Laser Technologies.- 1.2. How Lasers Deliver Short Pulses.- 1.3. Physics of Giant Light Pulses.- 1.4. Nonlinear Technologies.- 1.5. Detection of Picosecond Light Events.- 2. Use of Laser Pulses to Induce Biochemical Reactions.- 2.1. Photobiological Reactions.- 2.2. Chemical Relaxation.- 2.3. T Jumps.- 3. Use of Lasers for Monitoring Fast Biochemical Reactions.- 3.1. Multichannel Spectral Analyses.- 4. New Technologies in Multichannel Spectral Analysis.- References.- 4 The Excimer Laser: A New Ultraviolet Source for Medical, Biological, and Chemical Applications.- 1. Introduction.- 2. Physics of Excimers, and Limitations on Their Use as Laser Medium.- 3. Technology and Capabilities of Excimer Lasers.- 3.1. Excitation Techniques.- 3.2. Gas Mixtures.- 3.3. Optical Cavities.- 3.4. Wavelength Tuning.- 4. Applications.- 4.1. Photoassociation.- 4.2. Dermatology Response to Excimer Radiation.- 5. Future Improvements.- References.- 5 The Photopathology and Nature of the Blue Light and Near-UV Retinal Lesions Produced by Lasers and Other Optical Sources.- 1. Background and Current Status.- 2. Light Toxicity as Function of Wavelength.- 3. Aging and Degenerative Effects of Chronic Exposure to Light.- 4. Repetitive Exposures to Blue Light.- 5. Continuous Exposure of Rhesus Monkey to Fluorescent Light.- 6. Potential Eye Hazard from Ophthalmic Instrumentation.- 7. Photopathology of Blue Light.- 8. Photopathology of Near Ultraviolet Lesion.- 9. Validity of Animal Data as Related to Man.- 10. Protective Filtration.- 11. Possible Mechanisms Leading to Light Damage in the Primate Retina.- 12. Protective Mechanisms against Light Damage.- 13. The Effect of Oxygen on Light Toxicity.- 14. Summary.- References.- 6 Ocular Thermal Injury from Intense Light.- 1. History.- 2. Retinal Thermal Injury.- 2.1. Threshold Retinal Irradiance.- 2.2. Threshold Temperature.- 2.3. Temperature and the Damage Integral.- 2.4. Temperature Measurements.- 2.5. Blood Flow.- 2.6. Asymptotic Retinal Thermal Injury.- 3. Corneal Thermal Injury.- 4. Beyond Thermal Injury.- 5. Conclusion.- References.- Author Index.