1,721,007 research outputs found
Q-switched Cryogenic Ho:YAG Laser
No full textOSA Technical Digest (online) (Optical Society of America, 2018), paper SM4N.3.
From the session Laser Materials (SM4N)We describe the first power scalable, Q-switched, cryogenically cooled, resonantly pumped, Ho:YAG laser oscillator. The output energy was extracted from a confocal resonator with a single-pass pump geometry. Pulsed operation at higher average powers will be reported.Miftar Ganija, Alexander Hemming, Nikita Simakov, Neil Carmody, Peter Veitch, John Haub and Jesper Munc
High power cryogenic Ho:YAG laser
Full text linkWe have improved significantly the brightness of cryogenic Ho:YAG, reporting up to 65 W output power with a beam quality of M² <1.3 and a slope efficiency of 71%. The laser emission was ~2 nm wide and centered at 2097.5 nm. This result demonstrates the scalability of both the narrow-line thulium fibre pump laser and the cryogenic laser head.Miftar Ganija, Alexander Hemming, Nikita Simakov, Keiron Boyd, John Haub, Peter Veitch and Jesper Munc
A linearly polarised, pulsed Ho-doped fiber laser
No full textAbstract not availableSophie Hollitt, Nikita Simakov, Alexander Hemming, John Haub and Adrian Carte
Efficient, low threshold, cryogenic Ho:YAG laser
Full text linkPublished 18 May 2016Abstract not availableMiftar Ganija, Nikita Simakov, Alexander Hemming, John Haub, Peter Veitch, and Jesper Munc
A new guide star laser using optimized injection mode-locking
No full textAlso cited as: Proceedings of the SPIE; vol. 7015Abstract not availableJesper Munch, Thomas P. Rutten, Nikita Simakov, Murray Hamilton, Céline d'Orgeville, Peter J. Veitc
A bright, pulsed, guide star laser for very large telescopes
No full textWe demonstrate for the first time the practical feasibility of a new sodium guide star laser with a pulsed burst output of sufficient energy at 589nm to be useful for current applications and readily scalable to meet future requirements. We describe complete experimental design verification results of the pulse burst laser concept, optimized to eliminate guide-star elongation issues and to meet all requirements for Multi Conjugate Adaptive Optics (MCAO) for future extremely large ground-based telescopes (ELTs). It makes use of sum frequency generation (SFG) of two, Q-switched, injection mode-locked, wavelength stabilized Nd:YAG lasers, producing a macro-micro, pulse-burst output which is optimized in power and bandwidth to maximize the fluorescence from the high altitude sodium layer. © 2010 SPIE.Jesper Munch, Murray Hamilton, David Hosken, Nikita Simakov and Peter Veitc
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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