|
|
Structures in optical fiber
Polreich, Štěpán ; Čučka, Milan (referee) ; Urban, František (advisor)
This thesis describes the basic concepts, principles and basic characteristics od optical fibers. There are some particular types of structures of optical fibers and their use in practice. The work is also presented technology of these structures. For each of the structures is also described in which field are used, if is area of sensor technology or telecommunication technology. Considerable part is dedicated to special structures that are used especially in sensor technology thanks to its high sensitivity. The thesis describes the design of structures which have been machined by using a femtosecond laser and then states in which area thus treated fibers are used.
|
|
|
The system of Fabry-Perot and Michelson interferometer for length measurement with a femtosecond laser
Vémola, Tomáš ; Liška, Miroslav (referee) ; Číp, Ondřej (advisor)
The thesis deals with a design of a comparing interferometer. It concerns a setup of two interferometers, one of them is a Michelson and another a Fabry-Pérot type. This set-up is made to compare results of length measurements simultaneously performed by each of them. In the Theory, basic principles of Michelson and Fabry-Pérot interferometers are described. A special attention is paid to an innovative method of length measurement with tunable lasers and optical frequency comb. In the Practical Part, so-called Pilot Experimental Setup is described. It is a prototype that has been used to perform basic experiments on comparing of the two above mentioned methods. Based on experimental results and practical experience with the Pilot Experimental Setup, a Final Setup is designed. It comes in a form of a stand-alone instrument.
|
|
|
Femtosecond lasers and their applications
Oškera, Jakub ; Urban, František (referee) ; Münster, Petr (advisor)
Bachelor thesis deals with the definition of a laser, its properties and its use in practise. Work describes the basic principle of laser beam with associated individual laser types and comparison to conventional light radiation source. Next, work focuses on modes of transmission: continuous, pulse, and main differences among them. Next part describes femtosecond lasers and their generating pulses. The work contains theoretical design of measurements used for this particular laser. The theoretical concept is designed for the field of spectroscopy. The thesis mentions the basic methods of spectroscopy: ultravioletvisible, Raman and IR. Part of this work is also focused on WattJoule application software that has been programmed for the use in experimental measurement. This experimental measurement is described in the last part of this bachelor thesis. The purpose of the measurement is an attempt of connection of the laser beam into optical fiber. The conclusion discusses the description and outcome of this experimental measurement.
|
|
|
Two-photon photopolymerization with multiple laser beams
Skalický, Jiří ; Pilát,, Zdeněk (referee) ; Jákl,, Petr (advisor)
Photopolymerization is a technique used to create surface structures or microobjects from a photoresist. This process is started by illuminating the sample with a light of proper wavelength absorbed by the resist. After exposure, the sample is processed according to the type of the photoresist – be it heating, treating with developer or just washing the unaffected monomer with some reagent. Focused femtosecond laser beam with double wavelength can be used in the process. Short pulse length with high photon density starts two-photon absorption localized in the vicinity of focal point. The method resolution is thus increased and details with 1/10 micrometer size can be created. Moreover, very short laser pulse decreases the heat affected zone and the risk of thermal initiation is minimized. Manufacturing of larger structures composed of tiny details with two-photon photopolymerization is time-demanding process. Therefore, we have complemented the optical setup with spatial light modulator (SLM), which splits the incoming laser beam into several beams with holograms dynamically generated by a computer. Polymerization can be thus performed by multiple foci simultaneously which can be used to create separated microparticles or periodical surface structures. Additional speed improvement of the process can be substitution of static configuration, requiring sample replacement after each exposition, with continuous setup using microfluidic channel steadily supplied with photoresist transported to the active region of the sample.
|
|
|
The combined structures in optical fiber
Klvaňa, Jakub ; Čučka, Milan (referee) ; Urban, František (advisor)
The aim of this master’s thesis is familiar with the problems of optical fibers and possi- bilities creating functional optical structures in optical fibers. first section focuses on the optical fibers and their properties. Another chapter deals with the functional structures of optical fiber and their production. Next section is devoted to the analysis of combinations of these functional structures and their potential applications in sensors. Subsequently, a combined structure is proposed, which is later produced, measured and evaluated for possible use in the sensors
|
|
|
Longitudinal index structures in optical fibers
Polreich, Štěpán ; Čučka, Milan (referee) ; Urban, František (advisor)
This thesis describes basic concepts, principles and properties of optical fibers. Considerable part is devoted to fiber gratings that are created by a change in the refractive index in the optical fiber core. In this work is described description, principle, method od production and distribution of gratings on Bragg gratings, gratings with long period and chirped gratings. In this thesis are also presented different types of lasers and their advantages over other lasers. A large part deals with the description of the femtosecond laser, with which the structures will be later made into the material. In addition, the laser modes are differentiated, this is a mode of micro-machining and modification or a change in refractive index of the material. The last part deals with change the refractive index in planar technology, the creation of a groove for fastening the fiber and attempts to write the gratings into the optical fiber. Created fiber sensor are tested for temperature and tensile changes. Finally, the practical use of sensors made by femtosecond laser and the advantages over UV laser and phase mask techniques are presented.
|
|
|
Longitudinal index structures in optical fibers
Polreich, Štěpán ; Čučka, Milan (referee) ; Urban, František (advisor)
This thesis describes basic concepts, principles and properties of optical fibers. Considerable part is devoted to fiber gratings that are created by a change in the refractive index in the optical fiber core. In this work is described description, principle, method od production and distribution of gratings on Bragg gratings, gratings with long period and chirped gratings. In this thesis are also presented different types of lasers and their advantages over other lasers. A large part deals with the description of the femtosecond laser, with which the structures will be later made into the material. In addition, the laser modes are differentiated, this is a mode of micro-machining and modification or a change in refractive index of the material. The last part deals with change the refractive index in planar technology, the creation of a groove for fastening the fiber and attempts to write the gratings into the optical fiber. Created fiber sensor are tested for temperature and tensile changes. Finally, the practical use of sensors made by femtosecond laser and the advantages over UV laser and phase mask techniques are presented.
|
|
|
The combined structures in optical fiber
Klvaňa, Jakub ; Čučka, Milan (referee) ; Urban, František (advisor)
The aim of this master’s thesis is familiar with the problems of optical fibers and possi- bilities creating functional optical structures in optical fibers. first section focuses on the optical fibers and their properties. Another chapter deals with the functional structures of optical fiber and their production. Next section is devoted to the analysis of combinations of these functional structures and their potential applications in sensors. Subsequently, a combined structure is proposed, which is later produced, measured and evaluated for possible use in the sensors
|
|
|
Two-photon photopolymerization with multiple laser beams
Skalický, Jiří ; Pilát,, Zdeněk (referee) ; Jákl,, Petr (advisor)
Photopolymerization is a technique used to create surface structures or microobjects from a photoresist. This process is started by illuminating the sample with a light of proper wavelength absorbed by the resist. After exposure, the sample is processed according to the type of the photoresist – be it heating, treating with developer or just washing the unaffected monomer with some reagent. Focused femtosecond laser beam with double wavelength can be used in the process. Short pulse length with high photon density starts two-photon absorption localized in the vicinity of focal point. The method resolution is thus increased and details with 1/10 micrometer size can be created. Moreover, very short laser pulse decreases the heat affected zone and the risk of thermal initiation is minimized. Manufacturing of larger structures composed of tiny details with two-photon photopolymerization is time-demanding process. Therefore, we have complemented the optical setup with spatial light modulator (SLM), which splits the incoming laser beam into several beams with holograms dynamically generated by a computer. Polymerization can be thus performed by multiple foci simultaneously which can be used to create separated microparticles or periodical surface structures. Additional speed improvement of the process can be substitution of static configuration, requiring sample replacement after each exposition, with continuous setup using microfluidic channel steadily supplied with photoresist transported to the active region of the sample.
|
|
|
Femtosecond lasers and their applications
Oškera, Jakub ; Urban, František (referee) ; Münster, Petr (advisor)
Bachelor thesis deals with the definition of a laser, its properties and its use in practise. Work describes the basic principle of laser beam with associated individual laser types and comparison to conventional light radiation source. Next, work focuses on modes of transmission: continuous, pulse, and main differences among them. Next part describes femtosecond lasers and their generating pulses. The work contains theoretical design of measurements used for this particular laser. The theoretical concept is designed for the field of spectroscopy. The thesis mentions the basic methods of spectroscopy: ultravioletvisible, Raman and IR. Part of this work is also focused on WattJoule application software that has been programmed for the use in experimental measurement. This experimental measurement is described in the last part of this bachelor thesis. The purpose of the measurement is an attempt of connection of the laser beam into optical fiber. The conclusion discusses the description and outcome of this experimental measurement.
|
guest ::
