1,721,161 research outputs found
Saturation and tuning behaviour of stimulated electronic Raman scattering
No full textThe saturation behavior of stimulated electronic Raman scattering (SERS) in atomic vapors is studied theoretically and experimentally. Limits to the SERS output energy are imposed by both pump depletion and saturation of the Raman transition. The effects of these on the performance of tunable infrared lasers based on SERS are examined
Effects of spin-orbit coupling on resonant enhancement of stimulated electronic Raman scattering
No full textThe resonant enhancement and polarization properties of stimulated electronic Raman scattering by alkali metal atoms are investigated. Spin-orbit splitting of nearly-resonant intermediate levels results in a 90° rotation of the plane of polarization of the stimulated Stokes radiation. The relationship to two-photon absorption is also described
Stimulated electronic Raman scattering in Cs vapour: A simple tunable laser system for the 2.7 - 3.5µm region
No full textStimulated electronic Raman scattering (SERS) in atomic vapours provides a simple method of extending the tuning ranges of pulsed dye lasers well into the infrared region. The special advantages of this technique in comparison with other types of tunable infrared lasers are discussed, and are illustrated by describing a SERS system which uses a modest nitrogen laser-pumped dye laser (~20 kW). This produces infrared radiation tunable from 2.67 to 3.47µm by SERS in caesium vapour, which is contained in a heat pipe oven. Photon conversion efficiencies of up to 50% are obtained. The design of the heat pipe oven, operation of the system and optimization of experimental parameters are described in detail
Tunable infra-red lasers based on stimulated electronic Raman scattering in alkali vapours
No full textA high power widely tunable infra-red source based on stimulated electronic Raman scattering in Caesium vapour
No full textDye lasers pumped by the second harmonic of a ruby laser have been used to produce tunable stimulated electronic Raman scattering in caesium vapour. Using three different Raman transitions, the infrared tuning ranges were 2.5 -4.75µm. 5.67-8.65µm and 11.7-15µm with powers of up to 25kW, 7kW and 2kW respectively
Infra-red stimulated Raman generation effects of gain focusing on threshold and tuning behaviour
No full textIt is shown that for generation of infrared radiation by stimulated Raman scattering, the diffraction spread of the Stokes wave can have a significant effect on the threshold. Compared with an analysis in which gain focussing is neglected, the threshold powers may be much higher with a corresponding reduction in tuning range. The design of a Raman oscillator is considerably influenced by these diffraction effects, and also it is found that the Stokes wave is subject to frequency-pulling which is dependent on the pump power
Generation of tunable infrared radiation by stimulated Raman scattering in alkali vapours
Full text linkStimulated electronic Raman scattering in metal vapours provides a simple way of converting the tunable visible output of a pulsed dye laser into a tunable infrared output. Recent experimental results and their comparison with theoretical calculations will be presented
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
