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Laser

About: Laser is a research topic. Over the lifetime, 353128 publications have been published within this topic receiving 4379972 citations. The topic is also known as: light amplification by stimulated emission of radiation.


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Patent
A-Jung Kim1
25 Apr 2003
TL;DR: In this paper, an apparatus and method for enabling cost-effective duplex communication by diplexing one of down stream signals for frequency up-conversion in a hybrid fiber-radio system is presented.
Abstract: An apparatus and method for enabling cost-effective duplex communication by diplexing one of down stream signals for frequency up-conversion in a hybrid fiber-radio system includes diplexing an unmodulated mode signal among beating signals between a master laser and an injection-locked slave laser and using the diplexed signal for down-conversion in upstream transmission, thereby eliminating the need for expensive high-frequency local oscillators for frequency conversion. Higher radio frequency signals can be generated using beating between basic modes and satellite modes such as FWM conjugates of the master laser and slave laser. Cost-effective systems, stabilization of a light source and improved transmission performance may be achieved by using a diplexer instead of an expensive high-frequency local oscillator.

77 citations

Journal ArticleDOI
TL;DR: Laser-induced emission spectral analysis (LIESA) is a suitable method for the direct in-process measurement of elemental concentrations in various solid and liquid materials as discussed by the authors, which can yield information on the quality of the material and the fabrication process.
Abstract: Laser-induced emission spectral analysis (LIESA, a registered trademark of instruments developed by Krupp), better known in the literature as laser microanalysis or laser-induced breakdown spectroscopy, is a suitable method for the direct in-process measurement of elemental concentrations in various solid and liquid materials. This method has been developed recently by Krupp for in-process quality assurance and process control in different industrial branches such as steel production and plant making. As a result several LIESA instruments have already been developed or are under development for marketing. In all cases on-line and in-process elemental analysis of materials at various stages of production yield information on the quality of the material and the fabrication process. The beam of a pulsed high-power laser (irradiance: 1 × 108–5 × 109 W cm–2), focused onto the solid or liquid sample surface in an ambient gas atmosphere of normal pressure (focus area≈ablation area, 0.1–6 mm2), produces a hot bright plasma (early electron temperatures, 20000–30000 K). The emitted plasma light is observed end-on and passes by way of an optical fibre bundle to a spectrometer, where it is detected in the focal plane by means of an optical multichannel analyser with high time resolution (on the microsecond scale). A fast computer evaluates the measured spectra and calculates the element concentrations via calibration procedures. Relative detection limits of between 10 and 100 ppm can be achieved for most of the detectable elements in various matrices (steel, rubber, rock and glass). Procedures are available to convert relative measurements with relative standard deviations of between 1 and 2% into absolute concentration values with relative accuracies of about 3%.

77 citations

Patent
18 Jun 1996
TL;DR: In this article, a polygonal mirror is adapted to reflect the light beam so that a light beam reflected by the reflection mirror is used to read a source document placed at a position that is the conjugate of the position of the photosensitive drum surface with respect to the converging device.
Abstract: An optical scanning apparatus includes a semiconductor laser, a polygonal mirror as a deflector for scanning a light beam from the laser, a photosensitive drum for forming an electrostatic latent image, a converging lens for converging the light beam from the laser onto the photosensitive drum, and a reflection mirror located between the deflector and the photosensitive drum. The reflection mirror is adapted to reflect the light beam so that a light beam reflected by the reflection mirror is used to read a source document placed at a position that is the conjugate of the position of the photosensitive drum surface with respect to the converging device. Inside the casing of the semiconductor laser are a beam splitter for light path separation and a photosensor. The apparatus has an image reader section and a laser printer section, which share a common optical system, thus providing a compact design and cost reduction and also equalizes the accuracy of image reading and printing.

77 citations

Patent
18 Aug 2000
TL;DR: In this paper, an epitaxial structure is formed on the substrate with areas of different optical properties, and a laser and a photodetector are formed in the epitaxia structure.
Abstract: A wavelength converter assembly includes a substrate An epitaxial structure is formed on the substrate with areas of different optical properties A laser and a photodetector are formed in the epitaxial structure The photodetector generates a first electrical signal in response to an optical signal A conditioning circuit is coupled to the laser and the photodetector The conditioning circuit receives the first electrical signal and provides a second electrical signal to the laser to modulate its optical output

77 citations

Journal ArticleDOI
TL;DR: In this article, the use of vertical cavity surface emitting lasers (VCSELs) for optical trapping and active manipulation of live biological cells and microspheres was demonstrated using a 2-2 array of VCSEL arrays.
Abstract: We have demonstrated the use of vertical cavity surface emitting lasers (VCSELs) for optical trapping and active manipulation of live biological cells and microspheres. We have experimentally verified that the Laguerre‐Gaussian laser mode output from the VCSEL functions just as well as the traditional Gaussian fundamental laser mode for optically trapping biological cells and may be preferable since the highest intensity of the Laguerre‐Gaussian mode is located at the outer ring of the optical aperture, which allows for stronger optical confinement to be obtained for a lower total power. Another advantage that VCSELs have over conventional gas and diode lasers is their ability to be manufactured in an array form. Using a 2 � 2 array of VCSELs, the simultaneous and independent transport of four human red blood cells is demonstrated indicating that much larger two-dimensional VCSEL arrays can be used as individually addressable optical tweezers in biological chips and systems. This parallel transport capability will have a significant impact in currently developing biochip array and assay technologies through the facilitation of the selection, relocation, and precision placement of cells. # 2002 Elsevier Science B.V. All rights reserved.

77 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20238,153
202217,159
20217,219
202011,517
201913,976