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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Hodnocení optických prvků pro LED / Evaluation of optical components for LED

Dobiáš, Jiří January 2014 (has links)
This thesis deals with an evaluation of optical components for LED, which is based on laboratory measurements of available LED samples and optical elements. The evaluation is done according to established standards and is focused on efficiency and adjustment of luminous flux (beam angle, luminous curve). Furthermore was made a study engaged in an optical element influence on LED color properties (color temperature, spectral characteristics). In conclusion there is an optical elements usage overview and recommended procedure for selecting appropriate combination of LED and optical element.
32

Construction and analysis of numerical methods for solution of laser physics and nonlinear optics problems / Lazerių fizikos ir netiesinės optikos ir uždavinių sprendimo metodų sudarymas ir analizė

Laukaitytė, Inga 18 June 2010 (has links)
Mathematical models describing the Q-switched laser generation, which is a widely used laser technique for producing short intense pulses of light, belong to the class of semi-nonlinear models where only source terms nonlinearly depend on the solution. Numerical methods for solution of systems of semi-nonlinear partial differential equations have been extensively studied in many papers. Schrödinger-type equations, parabolic-type equations or general diffusion-reaction models arise in nonlinear optics. Such differential problems are solved mainly by finite-difference and Galerkin methods. The convergence analysis is based on the stability analysis of the linearized problems. The construction and theoretical analysis of discrete schemes for one-dimensional problem give a basis for a numerical solution of more general two-dimensional and three-dimensional problems where a diffraction process is taken into account. The two-dimensional problem simulates the dynamics of high-power semiconductor lasers. To solve the problems simulating propagation of photon fluxes in the nonlinear disperse medium, the finite-difference time-domain method is used. However, the major drawback of this method is that the computational domain must be sufficiently large. In order to restrict the computational domain and to solve the problem only in the region of interest, special artificial boundary conditions are investigated. The three-dimensional problem simulates an interaction of counter propagating... [to full text] / Disertacijoje nagrinėjami kai kurių lazerių fizikos ir netiesinės optikos uždavinių skaitinės analizės metodai. Tiriami trys pagrindiniai atvejai: bėgančias plokščias bangas aprašantis vienmatis, bėgančias difraguojančias bangas nagrinėjantis dvimatis ir lazerio pluoštų sąveiką netiesinėje Kero terpėje modeliuojantis trimatis modeliai. Šiuos uždavinius sieja pernešimo diferencialinės lygtys dalinėmis išvestinėmis, aprašančios į priešingas puses sklindančias lazerio bangas. Dvimačiame ir trimačiame uždaviniuose sprendžiamos dalinių išvestinių Šrėdingerio (ang. Schrödinger) tipo diferencialinės lygtys. Šiems matematiniams modeliams sudarytos baigtinių skirtumų schemos, atlikta jų analizė ir pagrindimas. Skaitinių eksperimentų realizacijai sukurti lygiagretieji algoritmai, jie yra būtini atliekant didelių resursų reikalaujančius skaičiavimus. Disertaciją sudaro įvadas, keturi skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sarašai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra. Pirmasis skyrius skirtas mokslinės literatūros apžvalgai ir supažindinimui su netiesinės optikos sąvokomis bei... [toliau žr. visą tekstą]
33

Lazerių fizikos ir netiesinės optikos ir uždavinių sprendimo metodų sudarymas ir analizė / Construction and analysis of numerical methods for solution of laser physics and nonlinear optics problems

Laukaitytė, Inga 18 June 2010 (has links)
Disertacijoje nagrinėjami kai kurių lazerių fizikos ir netiesinės optikos uždavinių skaitinės analizės metodai. Tiriami trys pagrindiniai atvejai: bėgančias plokščias bangas aprašantis vienmatis, bėgančias difraguojančias bangas nagrinėjantis dvimatis ir lazerio pluoštų sąveiką netiesinėje Kero terpėje modeliuojantis trimatis modeliai. Šiuos uždavinius sieja pernešimo diferencialinės lygtys dalinėmis išvestinėmis, aprašančios į priešingas puses sklindančias lazerio bangas. Dvimačiame ir trimačiame uždaviniuose sprendžiamos dalinių išvestinių Šrėdingerio (ang. Schrödinger) tipo diferencialinės lygtys. Šiems matematiniams modeliams sudarytos baigtinių skirtumų schemos, atlikta jų analizė ir pagrindimas. Skaitinių eksperimentų realizacijai sukurti lygiagretieji algoritmai, jie yra būtini atliekant didelių resursų reikalaujančius skaičiavimus. Disertaciją sudaro įvadas, keturi skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sarašai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra. Pirmasis skyrius skirtas mokslinės literatūros apžvalgai ir supažindinimui su netiesinės optikos sąvokomis bei... [toliau žr. visą tekstą] / Mathematical models describing the Q-switched laser generation, which is a widely used laser technique for producing short intense pulses of light, belong to the class of semi-nonlinear models where only source terms nonlinearly depend on the solution. Numerical methods for solution of systems of semi-nonlinear partial differential equations have been extensively studied in many papers. Schrödinger-type equations, parabolic-type equations or general diffusion-reaction models arise in nonlinear optics. Such differential problems are solved mainly by finite-difference and Galerkin methods. The convergence analysis is based on the stability analysis of the linearized problems. The construction and theoretical analysis of discrete schemes for one-dimensional problem give a basis for a numerical solution of more general two-dimensional and three-dimensional problems where a diffraction process is taken into account. The two-dimensional problem simulates the dynamics of high-power semiconductor lasers. To solve the problems simulating propagation of photon fluxes in the nonlinear disperse medium, the finite-difference time-domain method is used. However, the major drawback of this method is that the computational domain must be sufficiently large. In order to restrict the computational domain and to solve the problem only in the region of interest, special artificial boundary conditions are investigated. The three-dimensional problem simulates an interaction of counter propagating... [to full text]
34

Optická odezva magnetických materiálů / Optical response of magnetic materials

Wagenknecht, David January 2014 (has links)
David Wagenknecht: Abstract of a diploma thesis Optical response of magnetic materials, 2014 Magnetooptical properties of anisotropic semiconductors are studied to describe asymmetry of Ga1−xMnxAs, because theoretical calculations predict extraordinary behaviour of reflectivity. Analytical formulae to describe materials with non-diagonal permittivity are derived and they are used for the numerical calculations to describe the optical response of the samples available for the measurement. The transversal Kerr effect is calculated and it exhibits asymmetry in both rotation of the plane of polarization and ellipticity of circularly polarized light due to asymmetry in reflectivity. Moreover, longitudinal and polar magnetization are studied because of the influence on the observability of the phenomena. Results are not only used to discuss conditions, which must be satisfied to prove the asymmetry, but also the actual experimental setup is designed to prepare the measurement. 1
35

Inovovaná souprava pro demonstrační pokusy z optiky / Innovated set for demonstrative experiments from optics

VOCHOZKA, Vladimír January 2011 (has links)
This diploma work deals the possibilities of use of demonstration set in teaching of optics in the physics. It is focused on general use of technical didactical means in teaching and various approachs to experiments in the school physics. Comparison of actually available sets for demonstration experiments is incorporated in this work. It contains also set of selected experiments and worksheets which were used for verification of tasks. Results of the worksheets are analysed and form the part of the work. The aim is to verify the benefit of use of demonstration sets in the physics teaching.
36

Soubor výukových programů / The set of tutorial programs

Vaculík, Jakub Unknown Date (has links)
With increasing demands for transit capacity of data networks as well as communication network optical networks seem to be the suitable solution. Light beam is attractive to use for data transmission . Transmitted data can be expressed by means of light impuls.. For execution of the project we need the whole optical telecommunical system which consists of transmitter, transmission link and receiver. The target of transmission link is to transfer optical beam from its resourse to detector with minimal losses. The optical fibre or optical freespace optical link FSO are used for this purpose. This thesis discusses basic effects that accompany these roads. The program that is created in this study clearly shows and describes the dependence of these phenomena on the individual input parameters. It is designed for students so that they can better imagine how these phenomena take place.
37

Vysokovýkonný zdroj pikosekundových optických pulzů ve střední infračervené oblasti / High-average power picosecond mid-IR source

Vyvlečka, Michal January 2017 (has links)
1 Title: High-average power picosecond mid-IR source Author: Michal Vyvlečka Department: Department of Chemical Physics and Optics Supervisor: Ing. Ondřej Novák, Ph.D., Hilase centre, Institute of Physics of CAS Abstract: High average power wavelength tunable picosecond mid-IR source based on optical parametric generation (OPG) and optical parametric amplification (OPA) is being developed. The conversion system is pumped by an Yb:YAG thin-disk laser delivering 100 W of average power at 100 kHz repetition rate, 1030 nm wavelength, and 2-3 ps pulse width. Part of this fundamental beam pumps an OPG process in a PPLN crystal. The generated wavelength is determined by PPLN's poling period and temperature. Tunability of the signal wavelength between 1.46 µm and 1.95 µm was achieved, the signal beam of 20 mW was generated at 2 W of pump power, when double pass of the beams through PPLN crystal was used. The corresponding idler wavelengths were in range 2.18-3.50 μm. The signal beam was further amplified by OPA process in two KTP crystals, which was pumped by the fundamental beam. The signal beam was amplified up to 2 W at pumping of 38 W. Tuning of the output wavelength was realized by change of the phase-matching angle in KTP crystals. Tunability between 1.70-1.95 µm for signal and 2.18-2.62 µm for idler was...
38

Návrh kamerového systému na platformě VC5 a Vision Designer / VC5 and Vision Designer platform visual system

Popovský, Pavel January 2018 (has links)
For the purpose of an future machine vision system development in Tyco Electronics Czech s.r.o. I have developed Cognex Designer template. Template will serve as a flexible basis for further development of camera applications on the Cognex VC5 industrial computer. The functionality of the program template has been successfully verified by modifying it to a particular application of the laboratory manual station used to measure the parameters of the manufactured connectors. A camera with lens and lightning was chosen and installed on the station. DIO communication was put into operation between VC5 and PLC system. The application has been calibrated and verified as a measurement system using MSA Type I and Capability study standard methods.
39

Systém pro měření lokálních IR spekter / Local IR spectra measurement system

Pospíchal, David January 2021 (has links)
The diploma thesis deals with the design of a system for measuring infrared spectra from local areas of samples. The theoretical part describes the electromagnetic waves and related phenomena. Furthermore, the semiconductor junction and solar cells are discussed. The following is a basic description of line spectrometers. In the practical part, a suitable arrangement of the whole system, collimator design, and especially the core of the whole work, ie control software and signal processing, are proposed.
40

Design elektronového mikroskopu / Design of electron microscope

Havlíček, Petr January 2011 (has links)
The aim of my Master's thesis is the design of a scanning electron microscope. The designed concept presents an innovative approach to the problems and respects all technical, ergonomic and aesthetical demands made on it. The main creative part of design process starting from the concept development and ending up with the final solution is preceded by a background research study including a historical, technical and design analysis of the electron microscope. The conclusion of my Master's thesis analyses the final design, its character and its contribution in broader context.

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