scholarly journals Thermal lensing: outside of the lasing medium

2022 ◽  
Vol 128 (2) ◽  
Author(s):  
Krzysztof Dobek

AbstractThe thermal lens formed in a thermo-optical material as a result of its inhomogeneous heating, is a well-known phenomenon that has found widespread interest in the last decades, especially in the field of laser engineering and photo-thermal spectroscopy. In recent years, growing interest in the application of thermal lensing in different fields of optics and material studies has been observed. This review summarizes the latest efforts made by the scientific community to develop ways of using the phenomenon of thermal lensing. Its applications in spectroscopy, in laser beam formation and in imaging are described. The advantages and disadvantages of the thermal lensing in regard to these areas along with the potential future applications of the phenomenon are discussed.

Author(s):  
Hong Duc Doan ◽  
Yoshihiko Akamine ◽  
Kazuyoshi Fushinobu

Laser measurement and laser processing techniques have been gaining strong attention from various applications [1,2]. This research aims at the development of a fluidic laser beam shaper, and in order to fulfill the objective, characteristics of the thermal lens effect are studied. This phenomenon has the optical property of a concave lens since the refractive index distribution on the optical axis is formed when the liquid is irradiated. One reason for the refractive index distribution in the liquid is the temperature distribution in the liquid when it is irradiated. In this research, effects of the pump power and propagation distance of the probe beam to probe beam profile are investigated experimentally and theoretically, in order to develop fluidic laser beam shaper. It is indicated that, by controlling some parameters in thermal lens system as pump power (in the regime of linear optics) and absorption coefficient, input Gaussian beam can be converted into flat-top beam profile. The relationship among the distance to obtain a flat-top beam, pump power and absorption coefficient is investigated to show the flexibility of fluidic laser beam shaper in many fields of laser application.


2002 ◽  
Vol 41 (27) ◽  
pp. 5814 ◽  
Author(s):  
Victor I. Grishko ◽  
Chieu D. Tran ◽  
Walter W. Duley

2001 ◽  
Vol 40 (3) ◽  
pp. 366 ◽  
Author(s):  
Justin D. Mansell ◽  
Joseph Hennawi ◽  
Eric K. Gustafson ◽  
Martin M. Fejer ◽  
Robert L. Byer ◽  
...  

2020 ◽  
Vol 13 (2) ◽  
pp. 153-176
Author(s):  
A. F. Yakovleva ◽  
I. T. Mavrodieva ◽  
V. A. Boldin

The article analyzes the experience of development of electronic scientific journals in Russia and Bulgaria in the context of general trends of digitalization and transformation of the sphere of science management in recent decades and also the implementation of a strategy to increase the competitiveness of science in the global scientific community, which is reflected in the activities of scientific journals. The main problem that draws attention of the authors is how universal digitalization changes the usual view of science, affecting the development of periodicals, and how, on the contrary, the network form of social institutions of science affects its development, what place such journals occupy in the general view of science. The article examines the potential of journals in Russia and Bulgaria to promote the achievements of scientists, increase the credibility of representatives of individual scientific and educational institutions, meet the requirements of scientometrics, reflect the trends of transformation of the global scientific landscape, and fight against “fake” science. The object of the research is a number of journals in the fields of political science, philosophy, history, cultural studies, sociology, psychology, communications and information technologies published in Russia and Bulgaria, which originated as a network or use the network form as one of the main ones in their activities. The main method used in the study is an expert survey. The guide of the expert interview includes 18 questions in Russian and Bulgarian. A total of 12 interviews are conducted with editors-in-chief and members of editorial boards of 9 Russian journals, and 8 interviews with editors-in-chief of Bulgarian journals. The comparative analysis reveals similarities and differences in the goal setting of creating electronic journals, their advantages and disadvantages, the role of scientometrics, the choice of access forms and technological solutions for communication, and development prospects. The role of electronic journals in the digital socialization of scientists – authors, editors, and reviewers, and in the transformation of the usual forms of research activities of modern researchers is shown. The question of the key role of electronic journals in the fundamental change in the global scientific landscape at the same time identifies the problem of the crisis of confidence in e-magazines related to as with tradition, accepted by the scientific community, and with inadequate understanding of goal setting of electronic periodicals and their differences from print publications.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Stefan Reich ◽  
Sebastian Schäffer ◽  
Martin Lueck ◽  
Matthias Wickert ◽  
Jens Osterholz

AbstractWhen laser beams propagate through media with non-vanishing absorption, the media is heated resulting in a change of the refractive index, which can lead to thermal lensing and thermal blooming. However, experimental details about both phenomena for propagations in water are lacking, especially for high-power lasers in the kilowatt range. We show that significant thermal lensing occurs only for high input powers before the onset of convective flow, while for low input powers, no strong thermal lens arises. After the onset of water flow, thermal blooming occurs at low input powers comparable to that known for propagations over kilometres in the air. However, for high input powers a thermal blooming on a qualitatively higher level is shown. By wavefront sensing, the change of refractive index distribution in water is investigated. This clearly shows the fast development of a strong thermal lens for high input powers and the onset of convection. Furthermore, a qualitatively good agreement of the accompanying simulations is observed. It is found that the absorption coefficient is linear with a value of $$\mu ={13.7}\,{\mathrm{m}^{-1}}$$ μ = 13.7 m - 1 at least up to 7.5 kW, i.e. 8 $$\mathrm{kW/cm}^2$$ kW / cm 2 . However, the directed transmission into an aperture is only constant before any thermal lensing of blooming occurs.


Author(s):  
Aleksy Moldowan

The author states, that the theory of economic security of the state as a scientific discipline today is at the beginning of its new stage of development. A marked surge of interest in this topic is expected in the nearest future, that will intensify research activity in this scientific field. To meet these expectations scientific community needs a strong methodological platform, which should be based on universal and coherent categorical apparatus. However, a set of essential methodological problems may deteriorate a rise of the economic security of the state. One of the key problems is a significant number of scientific schools within the discipline. Most of them has developed their own categorical-conceptual apparatus. The author draws attention, that terminological chaos in the theory of economic security of the state as one of a serious problem for its institutionalization and development as an independent scientific discipline. It makes impossible to create a common methodological framework for discipline and undermines constructive scientific discussion between representatives of different scientific schools in this field. The huge differences between scientific schools are observed already at the stage of defining the basic definition of this scientific discipline - “economic security of the state”. A plenty of various approaches can be identified withing this scientific community. The differences between defining concept of “economic security of the state” are very deep indeed. This is a significant obstacle to create a common platform for numerous groups of scientists, who are working on various aspects of this topic. To resolve this problem and find common solution the author has analysed a majority of approaches of various scientific schools and individual scientists regarding the definition of the concept of “economic security of the state”. Their advantages and disadvantages have been identified. Based on knowledge obtained the author has proposed his own definition. According to it, “economic security of the state” should be treated as a state of the economy, that is intentionally and purposefully adjusted by public authorities in order to ensures the state's resilience to external and internal systemic threats and aggressive actions undertaken by other states. The author has justified the practicability of using this definition in the scientific research as well as policy-making.


1998 ◽  
Author(s):  
Tatyana Y. Cherezova ◽  
Sergei S. Chesnokov ◽  
Leonid N. Kaptsov ◽  
Alexis V. Kudryashov

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