Fundamental Principles of Lasers

The fundamental principles of lasers are covered only very briefly because many excellent textbooks on lasers already exist. 

American Academy of Ophthalmology. Clinical Optics. San Francisco American Academy of Ophthalmology, 2006. This volume of the American Academy of Ophthalmology basic science course covers the fundamental concepts of optics as it relates to lenses, refraction, and reflection. It also covers the basic optics of the human eye and the fundamental principles of lasers. 

Silfvast, W. T. (1996) Laser Fundamentals, Cambridge University Press, Cambridge. Svelto, O. (1998) Principles of Lasers, 2nd edn, Kluwer, Dordrecht. 

S. A. Rice My answer to Prof. Manz is that, as I indicated in my presentation, both the Brumer-Shapiro and the Tannor-Rice control schemes have been verified experimentally. To date, control of the branching ratio in a chemical reaction, or of any other process, by use of temporally and spectrally shaped laser fields has not been experimentally demonstrated. However, since all of the control schemes are based on the fundamental principles of quantum mechanics, it would be very strange (and disturbing) if they were not to be verified. This statement is not intended either to demean the experimental difficulties that must be overcome before any verification can be achieved or to imply that verification is unnecessary. Even though the principles of the several proposed control schemes are not in question, the implementation of the analysis of any particular case involves approximations, for example, the neglect of the influence of some states of the molecule on the reaction. Moreover, for lack of sufficient information, our understanding of the robustness of the proposed control schemes to the inevitable uncertainties introduced by, for example, fluctuations in the laser field, is very limited. Certainly, experimental verification of the various control schemes in a variety of cases will be very valuable. 

Figure 3.95. Fundamental principles of the LSCM (a) and the TPEM (b). In the LSCM, OP excitation laser light is condensed in a focal plane (endothelial layer) by an objective lens the light also excites upper (smooth muscle layer) and lower planes of the focal plane. However, fluorescence emission exclusively from the focal plane is detected through the pinhole. (From Ref. [105] with permission of The Japanese Pharmacological Society.)...

Although Raman spectroscopy does not employ absorption of infrared radiation as its fundamental principle of operation, it is combined with other infrared spectroscopies into a joint section. Results obtained with various Raman spectroscopies as described below cover vibrational properties of molecules at interfaces complementing infrared spectroscopy in many cases. A general overview of applications of laser Raman spectroscopy (LRS) as applied to electrochemical interfaces has been provided [342]. Spatially offset Raman spectroscopy (SORS) enables spatially resolved Raman spectroscopic investigations of multilayered systems based on the collection of scattered light from spatial regions of the samples offset from the point of illumination [343]. So far this technique has only been applied in various fields outside electrochemistry [344]. Fourth-order coherent Raman spectroscopy has been developed and applied to solid/liquid interfaces [345] applications in electrochemical systems have not been reported so far. 

In this paper a number of isotope separating processes will be examined, particularly those utilized on a large Industrial scale, and the bases for the above conclusions will be presented. Finally, the fundamental principles of a photochemical method of Isotope separation based upon excitation by laser light, which has excited a great deal of current Interest, will be outlined. 

For nonspecialists, however, or for people who are just starting in this field, it is often difficult to find from the many articles scattered over many journals a coherent representation of the basic principles of laser spectroscopy. This textbook intends to close this gap between the advanced research papers and the representation of fundamental principles and experimental techniques. It is addressed to physicists and chemists who want to study laser spectroscopy in more detail. Students who have some knowledge of atomic and molecular physics, electrodynamics, and optics should be able to follow the presentation. 

For studies in molecular physics, several characteristics of ultrafast laser pulses are of crucial importance. A fundamental consequence of the short duration of femtosecond laser pulses is that they are not truly monochromatic. This is usually considered one of the defining characteristics of laser radiation, but it is only true for laser radiation with pulse durations of a nanosecond (0.000 000 001s, or a million femtoseconds) or longer. Because the duration of a femtosecond pulse is so precisely known, the time-energy uncertainty principle of quantum mechanics imposes an inherent imprecision in its frequency, or colour. Femtosecond pulses must also be coherent, that is the peaks of the waves at different frequencies must come into periodic alignment to construct the overall pulse shape and intensity. The result is that femtosecond laser pulses are built from a range of frequencies the shorter the pulse, the greater the number of frequencies that it supports, and vice versa. 

The book starts with a short introduction to the fundamentals of optical spectroscopy, (Chapter 1) describing the basic standard equipment needed to measure optical spectra and the main optical magnitudes (the absorption coefficient, transmittance, reflectance, and luminescence efficiency) that can be measured with this equipment. The next two chapters (Chapters 2 and 3) are devoted to the main characteristics and the basic working principles of the general instrumentation used in optical spectroscopy. These include the light sources (lamp and lasers) used to excite the crystals, as well as the instrumentation used to detect and analyze the reflected, transmitted, scattered, or emitted light. 

The resolution of photoion laser microscopy is limited by two fundamental factors [7] the Heisenberg principle of uncertainty and the presence of the nonzero tangential component of the velocity of the ejected photoion (photoelectron). The same factors restrict the spatial resolution of the field-ion microscopy. It must be emphasized again that the key difference lies in the fact that for photoion microscopy there is no need for a strong (ionizing) electric field that distorts and desorbs the molecules. And also, the femtosecond laser radiation allows the photoion to be photoselectively extracted from certain parts of a molecule. 

Progress in the Raman spectroscopic study of carbohydrates became possible during the past few years owing to the introduction of laser sources. Before discussing the results of laser-Raman spectroscopy applied to carbohydrates, we shall give a brief recapitulation of the physical principles of the Raman effect. Experimental techniques of infrared spectroscopy have been described in previous reviews,116,17 but no such description has been given for the Raman method. That is why the Description Section, which follows, will include the physical fundamentals of the method, as well as the sampling techniques. 

Fig. 11.1. Principle of the nonlinear Thomson scattering X-ray source. The nonlinear motion of the free plasma electrons oscillating in the strong electromagnetic laser held (ao) produces high harmonics of the fundamental laser light that can reach the X-ray spectral range. As ao is increased, the radiation becomes more collimated...

With the advent of vector processors over the last ten years, the vector computer has become the most efficient and in some instances the only affordable way to solve certain computational problems. One such computer, the Texas Instruments Advanced Scientific Computer (ASC), has been used extensively at the Naval Research Laboratory to model atmospheric and combustion processes, dynamics of laser implosions, and other plasma physics problems. Furthermore, vectorization is achieved in these programs using standard Fortran. This paper will describe some of the hardware and software differences which distinguish the ASC from the more conventional scalar computer and review some of the fundamental principles behind vector program design. 

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