bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser Physics
Authors: Zayhowski John J. , Kelley Paul L. 
Published: August 2007

AbstractThis article concerns the physics of lasers, including population inversion, pumping processes, stimulated emission, and resonators. Important laser characteristics such as narrow spectral linewidth, high spatial collimation, and ultrashort pulses are discussed. A review is given of several types of laser media, laser dynamics, and modes of laser operation. Methods for control of laser output and practical considerations in laser design are considered. Finally, there is a discussion of nonlinear optical techniques for frequency conversion of laser radiation.
Lasers, Dye
Authors: Duarte Francisco J. , Foster David R. 
Published: August 2007

Abstract
Dye lasers are inherently tunable, and powerful, sources of narrow‐linewidth radiation. This means that dye lasers can change the emission color continuously while emitting radiation of extremely high spectral purity. In addition, these tunable lasers can be configured to yield extremely short pulses in the femtosecond regime. As such, dye lasers have found a wide variety of applications in fundamental physics, spectroscopy, medicine, and the military. In this article, basic aspects of dye‐laser operation are examined and explained. These include a discussion of the excitation process, via classical rate equations, the origin of tunability, and the theory of dispersion that explains the achievement of very narrow laser linewidths. Although most of the article deals with traditional liquid dye lasers, a section is devoted to newly developed solid‐state dye lasers. Important applications, such as laser isotope separation and laser cooling are also discussed.
Lasers, Free‐electron
Authors: Pellegrini Claudio , Reiche Sven 
Published: August 2007

AbstractFree‐electron lasers are radiation sources, based on the coherent emission of synchrotron radiation of relativistic electrons within an undulator or wiggler. The resonant radiation wavelength depends on the electron beam energy and can be tuned over the entire spectrum from micrometer to X‐ray radiation. The emission level of free‐electron lasers is several orders of magnitude larger than the emission level of spontaneous synchrotron radiation, because the interaction between the electron beam and the radiation field modulates the beam current with the periodicity of the resonant radiation wavelength. The high brightness and the spectral range of this kind of radiation source allows studying physical and chemical processes on a femtosecond scale with angstrom resolution.
Lasers, Gas
Authors: Eden J. Gary , Eichler Jürgen 
Published: August 2007

AbstractThis article reviews the characteristics of gas lasers that are chiefly responsible for their effectiveness as both scientific and industrial tool. The basic principles common to operation of all gas lasers and a few of their general properties are discussed. The lasers are categorized according to the pumping mechanisms: electron‐impact excitation (copper and gold laser, Ar‐ and Kr‐ion lasers), excitation transfer (He–Ne laser, He–Cd laser, CO2laser), reactive collision lasers (excimer laser (ArF, KrF, XeCl, XeF, F2), chemical lasers (HF, COIL)), and other lasers in the far infrared, ultraviolet, and soft X‐ray region. Selected applications of pulsed and continuous gas lasers are presented in material processing, marking and laser evaporation, microlithography, photochemical processing, stereolithography, and medicine.
Lidar (Laser Radar)
Authors: Argall P. S. , Sica R. J. 
Published: August 2007

Abstract
Lidar is an active remote sensing technique similar in principle to radar, except that it utilizes light rather than radio waves. Lidar finds applications in many areas, including atmospheric and oceanic research, digital mapping, chemical and biological agent detection, speed measurement, and targeting. This chapter describes the principles of lidar and provides examples of the application of lidar in measuring the properties of the Earth's atmosphere.
Luminescence
Authors: Hofmann Detlev M. , Böhm Manfred 
Published: August 2007

Abstract
The article gives an introduction to the widespread phenomenon of light emission from matter under the aspect of the most common stimulation sources, that is, the use of photons for photoluminescence, or electron beams for cathodoluminescence, electric fields in the case of electroluminescence, chemical energy for chemiluminescence, sound waves for sonoluminescence, or thermal energy for the stimulation of the thermoluminescence phenomena. It focuses mostly on the respective principles of the luminescence excitation, rather than an overview of the uncountable applications of the methods in all areas of science, technology, and engineering.
Microscopy
Authors: Hellmuth Thomas 
Published: August 2007

AbstractPrinciples, methods, and applications of light microscopy, electron microscopy, and scanning probe microscopy are described and complemented by related techniques such as ultrasound microscopy, field‐emission microscopy and X‐ray microscopy. Advanced methods such as Raman microscopy, low‐energy electron microscopy, and scanning near‐field microscopy representing new trends in the field of microscopy are discussed.
Modulators and Demodulators, Optical
Authors: LiKamWa Patrick , Yao Shi‐Kay , Young Eddie H. 
Published: August 2007

AbstractModulation is a means of adding a signal information to an energy carrier used for transmission. Demodulation is the process of extracting the signal information from the carrier. Electromagnetic waves have been used extensively as the carrier for radio and television broadcasting as well as wireless and satellite telephony and data communications. Optical waves are electromagnetic waves that are at the much higher end of the frequency spectrum compared to radio frequencies. Therefore, information can be sent at much higher rates using optical carrier waves than using radio waves. In this chapter, the application and the technology of various optical modulators are described. The various forms of modulation formats and demodulation techniques are also discussed.
Optical Aberrations
Authors: Turner Mary G. 
Published: August 2007

Abstract
A spherical wave front propagating through the optical system, by the time it exits the system, is often no longer perfectly spherical. The departure of any wave front that is exiting the optical system from the ideal spherical reference can be described by an aberration function. The aberration function can be expressed in the form of different polynomials. The optical system that introduces aberrations does not form a stigmatic or ideal image. The distribution of energy at the image surface for different wave front aberrations can be described by ray aberration functions. Wave and ray aberrations are closely related. This article presents the basics optical aberrations, commonly expressed in these two forms.
Optical Computing
Authors: Tanida Jun , Ichioka Yoshiki 
Published: August 2007

Abstract
Optical computing is an area of technology for information processing that utilizes excellent features of light. Beginning with some historical background of this technological field, the concept of optical computing is described with respect to definition, motivation, advantages, targets, and classifications. Then two major categories, analog optical computing and digital optical computing, are used to explain concrete instances of this technology. Analog optical computing includes Fourier image processing, acoustooptical signal processing, optical neural computing, and spatiotemporal information processing. Digital optical computing covers logic gates and circuit constructions, computing paradigms, optical computer architectures, and VLSI photonics. Finally, some comments on potential applications of optical computing are added to suggest effective areas for this technological field.
Optical Materials
Authors: Jellison Gerald E. 
Published: August 2007

Abstract
Transparent optical materials are used in a variety of applications ranging from the very common, such as corrective lenses, to the very sophisticated, such as fiber‐optic communications. As common as these applications are, optical materials possess many interesting and complicating properties, which are often ignored. For example, all optical materials absorb light in some spectral regions, and all materials experience dispersion, where the refractive index is a function of the wavelength of light. In this chapter, the basic physics of light interaction with optical materials is presented, primarily to explain many of these commonly observed phenomena. The emphasis of the chapter is on materials that are transparent in the region from the ultraviolet (down to ∼120 nm) to the mid‐infrared (up to ∼40 microns). Perturbations of the basic optical properties of materials, such as those due to external strain and electric fields, will also be discussed. The properties of several specific optical materials will be discussed with the intent of demonstrating the basic physics and not to present a comprehensive listing of optical data. Thin films (that is, films with thicknesses on the order of the wavelength of light) are also discussed with the intent of understanding the physics of these materials and how they interact with light to produce the desired affects, such as reducing or enhancing the amount of light transmitted through or reflected from an optical device.
Optical Tomography
Authors: Hillman Elizabeth M. C. 
Published: August 2007

AbstractOptical tomography (OT) is an imaging technique that uses near‐infrared (NIR) and visible light to resolve the internal structure of scattering objects. OT has recently been the focus of much development as a method for imaging living tissue such as the breast and brain. By using NIR light, it is possible to investigate the hemoglobin in bloodin vivo, since hemoglobin is a strong NIR absorber compared to other tissue constituents. Using spectroscopic techniques to extract the oxygenation state of the hemoglobin in tissue can provide information about the functional state of the tissue, allowing detection of tumors, hemorrhages, and other abnormalities. This article introduces the basic concepts of medical OT, giving two detailed examples of instrumental approaches. The physics of light propagation in scattering tissue and the various techniques for tomographic image reconstruction are then detailed, followed by a review of some of the latest novel approaches to OT.
Photoemission and Photoelectron Spectra
Authors: Himpsel Franz J. , Lindau Ingolf 
Published: August 2007

AbstractApplications of photoelectron spectroscopy and related techniques are reviewed. They include photoelectric yield spectroscopy, absorption spectroscopy from core levels, photoelectron spectroscopy of core‐level shifts (XPS or ESCA), angle‐resolved photoemission and inverse photoemission, EXAFS, and photoelectron diffraction. These techniques provide information about structure, bonding, and electronic states of atoms, molecules, solids, surfaces, and nanostructures. Advances in detectors and light sources, such as high‐resolution multidetection and synchrotron radiation from undulators, are breaking ground for new applications. Among those are element‐resolved microscopy and high‐resolution spectroscopy of the electronic states relevant to magnetism, superconductivity, and transport properties.
Photographic Recording
Authors: Szajewski Richard P. 
Published: August 2007

AbstractPhotographic recording of images encompasses the capture and storage steps of the imaging chain. Currently, both traditional silver halide films and silicon devices allow high‐quality images to be obtained. Factors influencing the sensitivity and quality performance of the imaging materials for recording images are reviewed with examples of applications to specific imaging tasks. The physical mechanisms applicable to imaging materials and design issues for films and sensor arrays involve compromises between high sensitivity and the ability to record sufficient information density for a high‐quality image. Appropriate imaging materials for holographic recording, the infrared region, and X ray are mentioned.
Speckle and Speckle Metrology
Authors: Joenathan Charles , Tiziani Hans J. 
Published: August 2007

Abstract
Speckles are a three‐dimensional self interference pattern formed by a large number of random coherent waves. This results in a granular structure in free space or can be observed to be superposed on the image of the object and sets a fundamental limitation in high‐resolution hologram microscopy and coherent imagery. Essentially, speckles are a randomly coded pattern that carries information about the object surface, and also has the rare distinction of being a nuisance and simultaneously a useful tool for measurement. Emergence of better measurement capabilities, newer recording media, faster computers and interfaces, and software has revitalized speckle metrology and has resulted in many fascinating new developments. Scores of books and review articles cover the myriads of applications and developments, and this chapter is intended to provide a concise and precise account of speckles starting from its infancy to the latest developments such as temporal speckle pattern interferometry or digital holography. Attractiveness of speckle methods lies in their ability to measure: large deformations, displacements with variable sensitivity to in‐plane and out‐of‐plane, displacement derivatives, shape of a three‐dimensional object, surface roughness, and dynamic displacement. Speckle techniques can nowadays be used to measure a wide range of displacement, sensitivities ranging from 0.25 µm to 150 µm for in‐plane and 0.05 to 150 µm for out‐of‐plane displacements and with shearing techniques to over a 1000 µm.
Spectrometers, Ultraviolet and Visible Light
Authors: Hardwick John L. 
Published: August 2007

AbstractA wide variety of instruments exist for recording the intensity of light as a function of wavelength. In the visible and ultraviolet regions of the spectrum, these include dispersive spectrometers (based on gratings and prisms) and nondispersive spectrometers (usually interferometric in nature). A discussion of the main kinds of visible and ultraviolet spectrometers is given along with their advantages and drawbacks in terms of resolution, accuracy, efficiency, and ease of use. Considerations for choosing the design of an optical spectrometer are outlined, and the main aberrations associated with common optical designs are discussed.
Spectrometers,X‐ray
Authors: Markert Thomas H. , Förster Eckhart 
Published: August 2007

AbstractX‐ray spectrometers are used in many fields of pure and applied science as well as in industry. They are employed to investigate cosmic and laboratory high‐temperature plasmas where a high spectral resolution in the emission spectra is required. Commercial X‐ray spectrometers register X‐ray fluorescence of a sample under X‐ray irradiation or electron bombardment. In this case, registration of a wide spectral range with moderate resolution is performed to obtain the elemental composition of a sample.The main experimental parameters of a spectrometer are its resolving power, sensitivity, and breadth of spectral coverage. Dispersive spectrometers that use X‐ray crystal diffraction to widen the incident spectrum have great advantages in spectral resolution. To raise their sensitivity, different X‐ray optics such as grazing incident mirrors, polycapillaries, bent gratings, or bent crystals are implemented. Nondispersive spectrometers that convert the energy of an incident X ray into a number of “particles” (electron–hole pairs, electron–ion pairs, phonons, etc.) have a moderate spectral resolution, good sensitivity, and wide breadth of spectral coverage. Recently developed microcalorimeters need a complex cryogenic system for the detector but have a competitive spectral resolution as dispersive spectrometers.
Optical Networks
Authors: Alferness Rod C. , Kogelnik Herwig , Wood Thomas H. 
Published: August 2007

AbstractWith the explosion of capacity demands driven by the Internet, optical networking systems are experiencing tremendous growth and are providing increasingly high transmission capacities. As importantly, with the advent of the optical amplifier and wavelength‐division multiplexing (WDM), optics is playing a larger role in networking and is extending further to the edge of the network. Once limited to long‐haul point‐to‐point systems, the industry is now commercializing multipoint metro WDM ring systems that include software‐controlled optical wavelength add/drop multiplexers and will soon be capable of offering large optical cross connects. These optical network elements, together with network‐management software, will enable rapid provisioning of wavelength services, as well as rapid network restoration. In addition, as the cost of optics is driven down and the demand for bandwidth to businesses and residential customers continues to grow, optical systems are extending out from the network core and metro to access applications. The confluence of a proliferation of broadband service applications and rapidly maturing optical technology are literally driving optical systems into all segments. Increasingly, optics is literally everywhere.
Dendrimer‐Functionalized Iron Oxide Nanoparticles for Specific Targeting and Imaging of Cancer Cells
Authors: Wang S. H. , Shi X. , Van Antwerp M. , Cao Z. , Swanson S. D. , Bi X. , Baker J. R. 
Published: August 2007

AbstractWe demonstrated a unique approach that combines a layer‐by‐layer (LbL) self‐assembly method with dendrimer chemistry to functionalize Fe3O4 nanoparticles (NPs) for specific targeting and imaging of cancer cells. In this approach, positively charged Fe3O4 NPs (8.4 nm in diameter) synthesized by controlled co‐precipitation of FeII and FeIII ions were modified with a bilayer composed of polystyrene sulfonate sodium salt and folic acid (FA)‐ and fluorescein isothiocyanate (FI)‐functionalized poly(amidoamine) dendrimers of generation 5 (G5.NH2‐FI‐FA) through electrostatic LbL assembly, followed by an acetylation reaction to neutralize the remaining surface amine groups of G5 dendrimers. Combined flow cytometry, confocal microscopy, transmission electron microscopy, and magnetic resonance imaging studies show that Fe3O4/PSS/G5.NHAc‐FI‐FA NPs can specifically target cancer cells overexpressing FA receptors. The present approach to functionalizing Fe3O4 NPs opens a new avenue to fabricating various NPs for numerous biological sensing and therapeutic applications.
Photophysical Properties of a Series of Poly(ladder‐type phenylene)s
Authors: Laquai F. , Mishra A. K. , Ribas M. R. , Petrozza A. , Jacob J. , Akcelrud L. , Müllen K. , Friend R. H. , Wegner G. 
Published: August 2007

AbstractThe photophysical properties, i.e., the fluorescence and phosphorescence of a series of blue light‐emitting poly(ladder‐type phenylene)s have been investigated employing continuous‐wave (cw) and time‐resolved photoluminescence (PL) spectroscopy in solid state and dilute solution. The chemically well‐defined polymers vary from two to five bridged phenyl‐rings per monomer unit bearing aryl‐ or alkyl‐substitution at the bridge‐head carbon atoms. It has been found that the fluorescence energy of the polymers and of the corresponding monomers deviates from a simple 1/N dependence, if the number N of bridged‐phenylene rings is increased beyond a certain limit. Time‐resolved fluorescence spectroscopy on thin films showed that apart from the blue fluorescence of the polymers an additional lower energy emission feature exists, which cannot be assigned to keto‐defects and which seems to be an inherent solid state property of this class of materials. Delayed time‐resolved photoluminescence spectroscopy allowed the detection of phosphorescence energies and lifetimes for all investigated polymers. Photoinduced absorption spectroscopy on thin films showed that the triplet‐triplet absorption red‐shifts with increasing monomer length but reaches a constant value for polymers with N ≥ 4. Amplification of light via amplified spontaneous emission (ASE) from thin film slab waveguide structures could be demonstrated for all ladder‐type polymers but the onset threshold value for ASE varies significantly with the polymer structure.
The Electrochemical Behavior and Direct Determination of Tyrosine at a Glassy Carbon Electrode Modified with Poly (9‐Aminoacridine)
Authors: Fang Bin , Liu Hongying , Wang Guangfeng , Zhou Yunyou , Li Maoguo , Yu Yan , Zhang Wei 
Published: September 2007

Abstract9‐aminoacridine was firstly immobilized on the surface of a glassy carbon electrode to form a poly (9‐aminoacridine) film modified electrode. The results demonstrated that the modified electrode exhibited a high degree of catalytic activity towards the oxidation of tyrosine and can resolve the interference of tryptophan in the determination of tyrosine. Compared with the bare electrode, the peak current had obviously increased, and the peak potential had shifted in a negative direction. Under the optimum conditions, a linear response to tyrosine was observed in the concentration of 1.0×10‐6‐2.8×10‐3 M, with a correlation coefficient of 0.9987, and a detection limit (S/N=3) of 1.0×10‐7 M. The modified electrode has been successfully applied to determine the concentration of tyrosine in composite amino acid injections; and it displays excellent repeatability and high sensitivity. The proposed sensor has promising features such as ease of fabrication, good reproducibility, high stability and low cost. And most of all, it has good selectivity.
Measurements of lower Carbonyls and Hydrocarbons at Ny‐Alesund, Svalbard
Authors: Mabilia Rosanna , Di Palo Vincenzo , Cassardo Claudio , Ciuchini Carla , Pasini Antonello , Possanzini Massimiliano 
Published: September 2007

AbstractMeasurements of gaseous organic compounds were carried out near Ny‐Alesund, in the Norwegian Arctic, during September 2004. Twenty alkanes, alkenes and aromatic hydrocarbons from ethane to toluene and six aldehydes and ketones from formaldehyde to butanal, were identified and quantified in air samples. Hydrocarbons showed a quite uniform distribution, with ethane being by far the most abundant component (>1 ppb), followed by propane (>0.4 ppb) and butanes (>0.3 ppb), while for unsaturated homologues, except ethene, concentrations never exceeding 0.05 ppb were observed. This distribution confirmed that hydrocarbon depletion during the transport time from Europe into the Arctic was depending upon their atmospheric lifetimes, calculated relatively to the OH reactivity scale. The presence of short lived hydrocarbons could be associated to local sources of anthropogenic and/or biogenic origin. Although the local air photochemistry played a primary role in the production of lower aldehydes in late summer, the observed mixing ratios of formaldehyde (in the 0.25 – 0.50 ppb range) could not be fully explained by known gas‐phase chemistry. In this case additional sources, such as fluxes of formaldehyde from snow pack to the atmosphere and/or local anthropogenic activities, were to be taken into consideration. The possible influences of these sources on HCHO mixing ratios were analysed by means of a backward‐trajectory circulation model.