Šviesos sūkurių formavimas ir jų tiesinės bei netiesinės transformacijos

The topic of this dissertation is one of the more popular themes in optics – the optical vortices, which have several practical applications such as the STED microscopy, optical tweezers and optical vortex coronagraphs in astronomy. In this work various ways to generate the optical vortices are investigated as well as their transformations during the propagation in linear and nonlinear optical media. The performed research is presented in five chapters of the dissertation: 1) A possibility to generate half-charged vortices using a radial polarization converter is investigated theoretically and demonstrated experimentally. 2) A new method is proposed and investigated, which allows generation of a doubly-charged vortex with a single radial polarization converter. 3) A computerized way to control optical vortex positions by means of a collinear interference with a Gaussian beam is presented and demonstrated experimentally. 4) The topological charge conservation in second harmonic generation pumped by a half-charged optical vortex is confirmed poth theoretically and experimentally. The second harmonic beam carries a unit-charged vortex. 5) A new method to generate radially and azimuthally polarized beams is proposed and investigated theoretically as well es demonstrated experimentally. The method uses the optical parametric amplification of an optical vortex

Generation of optical vortices and their linear and nonlinear transformations

The topic of this dissertation is one of the more popular themes in optics – the optical vortices, which have several practical applications such as the STED microscopy, optical tweezers and optical vortex coronagraphs in astronomy. In this work various ways to generate the optical vortices are investigated as well as their transformations during the propagation in linear and nonlinear optical media. The performed research is presented in five chapters of the dissertation: 1) A possibility to generate half-charged vortices using a radial polarization converter is investigated theoretically and demonstrated experimentally. 2) A new method is proposed and investigated, which allows generation of a doubly-charged vortex with a single radial polarization converter. 3) A computerized way to control optical vortex positions by means of a collinear interference with a Gaussian beam is presented and demonstrated experimentally. 4) The topological charge conservation in second harmonic generation pumped by a half-charged optical vortex is confirmed poth theoretically and experimentally. The second harmonic beam carries a unit-charged vortex. 5) A new method to generate radially and azimuthally polarized beams is proposed and investigated theoretically as well es demonstrated experimentally. The method uses the optical parametric amplification of an optical vortex

The influence of different type of warm-up on basketball vertical jump and 20-meter sprint results and their change during the match

Krepšinyje per rungtynes labai svarbu gebėti nuolat su pertraukomis atlikti didelio intensyvumo veiksmus ir mažo intensyvumo veiksmų ir / arba atsigavimo derinius. Didelio intensyvumo judesiai, tokie kaip šuolis į viršų (kovoti dėl atšokusio kamuolio, blokuoti varžovų metimus ir atlikti metimus), krypties keitimas, kamuolio varymas, pagreitėjimas, užtvaros, bei mažo intensyvumo veikla, tokia kaip vaikščiojimas, stabdymas, neintensyvus aerobinis darbas, reikalingi norint pasiekti gerų rezultatų krepšinio rungtynėse. Krepšinyje, kaip ir bet kuriame kitame sporte, tiek prieš rungtynes, tiek prieš treniruotes yra būtina paruošti organizmą būsimai veiklai. Tai atliekama pramankštos metu, kuri yra reikalinga, kad būtų pasiektas optimalus pasirodymas ir pasirengimas rungtynių ar treniruočių krūviams. Mūsų tyrimo tikslas – nustatyti skirtingų tipų pramankštos poveikį krepšininkų galingumo rodikliams ir jų kaitai rungtynių metu. Tyrimo metu buvo atliekama dviejų tipų pramankšta: anaerobinio alaktatinio ir anaerobinio alaktatinio / laktatinio. Tyrime dalyvavo didelio meistriškumo krepšininkai (n = 20). Prieš pramankštą, po jos ir tarp krepšinio rungtynių kėlinių buvo atliekami vertikalaus šuolio bei 20 m bėgimo iš starto testai. Išanalizavus tyrimo rezultatus nustatyta, kad tiek anaerobinio alaktatinio, tiek anaerobinio alaktatinio / laktatinio tipo pramankšta reikšmingai pagerino vertikalaus šuolio rezultatus, tačiau anaerobinio alaktatinio tipo pramankšta, kurioje buvo taikomas raumenų potenciaciją sukeliantis fizinis krūvis, labiau pagerino vertikalaus šuolio rezultatus nei anaerobinio alaktatinio / laktatinio tipo pramankšta (p < 0,05). Įvertinus galingumą atspindinčių testų rezultatų kaitą rungtynių metu nustatyta, kad po visų kėlinių tiek vertikalaus šuolio, tiek 20 m bėgimo rezultatai geresni buvo tos grupės tiriamųjų, kurie prieš rungtynes atliko anaerobinio alaktatinio tipo pramankštą. Tyrimas atskleidė, kad didelio meistriškumo krepšininkams efektyviausia taikyti anaerobinio alaktatinio tipo pramankštą, į kurią būtų įtraukti raumenų potenciaciją sukeliantys pratimai. Tokio tipo pramankšta labiausiai pagerina galingumą atspindinčių testų rezultatus ir jų kaitą rungtynių metu.In basketball, during the game player must be able to continuously perform intermittent activities ranging from low- to high-intensity activity and/or recovery. High-intensity intermittent activities such as jumps (rebounds, blocks, shots), change of direction, dribbling, sprints, screens and low-intensity activities such as walking, deceleration are necessary in order to succeed during basketball games. In order to do a training session or play a basketball games the preparation of the body is necessary. We achieve this goal during the warm-up which is the main factor for achieving the optimal performance and to be ready for training or game related loads. The main aim of our study was to investigate the effect of different warm-ups on basketball player’s power indicators during simulated basketball games. Two different types of warm-up were analysed: anaerobic alactic and anaerobic alactic/lactic. Twenty high level basketball players were recruited for this study. Countermovement jump (CMJ) and 20-meter sprint were measured before the warm-up, after the warm-up and after each quarter of the simulated basketball games. It was found, that both anaerobic alactic and anaerobic alactic/ lactic warm-ups significantly increased CMJ, however the anaerobic alactic warm-up group which had muscle potentiation loads during the warm-up routine showed better results in CMJ compered to anaerobic alaktic/ lactic warm-up group (p < 0.05). Evaluation of the power reflecting tests results during the simulated basketball game showed that both CMJ and 20-meter sprint results were better in anaerobic alactic warm-up group. These findings suggests that anaerobic alactic warm-up with potentiating exercises is the most effective for basketball players. This type of warm-up increases the power reflecting tests results during the simulated games the most