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Design of stabilized optical source
Novák, Michal ; Chmelař, Milan (referee) ; Filka, Miloslav (advisor)
The aim was to design a stabilized optical light source operating at a wavelength of 1 625nm, suitable for measuring the attenuation of optical fiber transmission method. Source should be stabilized by optical feedback and output should be washed 0dB, 5 db and 10 db. There have been described in various peripheral components such as LEDs and laser diodes, the method of dividing the optical signal and its measurement of a PIN photodiode and avalanche photodiode. Furthermore, optical attenuator, which in this design has played an important role. With it's optical power is stabilized. They were also briefly described three basic methods of measuring attenuation of optical lines. Proposal for construction has been described switched power supply that provides voltage and current surge into the laser diode and the voltage stabilizer is used to power optical attenuator. The work also solved the optical attenuator control voltage output current from the photodiode.
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Photoreceivers with modern integrated circuits
Matyáš, Petr ; Murina, Milan (referee) ; Drexler, Petr (advisor)
The main goal of the bachelors project is to find the proper device to design a receiver of the anologue modulated optical signal. The only condition is to use the device, which is able to output the signal of 100 MHz bandwidth. The theoretical part concerned on description of main types of a photodiode and its basic features, its advantages and disadvantages. Different circuit applications of photodiode are presented. The main advantages of using operational amplifiers in those circuits are shown. In the next part of the project a few types of circuit connections of photodiode are presented. The circuit with transimpedance amplifier is chosen as the most suitable for the required application. The next step is to select the proper electronic device. According to technical catalogues classical operational amplifier TEXAS INSTRUMENT OPA657 was proposed. Nevertheless program simulation of the designed cicuit shows that required bandwidth cannot be reached with this device. At last transimpedance amplifier ANALOG DEVICES AD8015 comes into account as suitable solution. Final analysis and calculation determine the designed circuit with this device for range up to 240MHz of output signal.
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Program for the free space optical link power budged calculation
Vaculík, Jakub ; Hudcová, Lucie (referee) ; Křivák, Petr (advisor)
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. Connection to internet by optical fibre is out of reach for most households and plants, it is very expensive and so far it isn´t in the offer of network operators and service providers. (at lest in our condition). But there is still the posibility to obviate optical fibre networks and reach high permeability and safety of communication by means of freespace optical links. It is much easier to implement, but only for short distance. FSO enables quick and even ecological communication which is in the world of more famous radio frequency networks very pleasant message.
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Optical detection of electrograms
Hanák, Pavel ; Kozumplík, Jiří (referee) ; Chmelař, Milan (advisor)
The aim of the study was focused on problem of electrograms recording with using voltage sensitive dyes. Study of electrograms recording was extended with thema of optical detectors suitable for measurement and noise analysis. Elimination of noise and disturption was made in program Matlab; lowpass filtration and wavelet transformation was used. Application for electrograms analysis was developed in latter part of this work.
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Low-range high-speed optical transceiver
Pučálka, Jan ; Tošovský, Petr (referee) ; Kubíček, Michal (advisor)
The diploma thesis deals with description and design of a low-cost free-space optical (FSO) link. First, general FSO theory is discussed including their common parameters, properties and topologies. Further, optical signal sources and detectors are proposed. Finally, the selected implementation is described including its design and realization. The proposed FSO consists of two identical segments (modules) to form a full-duplex link. The FSO utilizes LED as a light source, maximum speed data rate is 100 Mb/s with 100Base-TX interface.
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Converter card for precise control of a laser diode
Čožík, Ondřej ; Kadlec, Jaroslav (referee) ; Fiedler, Petr (advisor)
The diploma thesis deals with design of the converter card for the precise control of a laser diode. At first, there are described the principles of the laser diode, photodiode and basic functions of optical fiber sensors. Following chapter deals with description of developed converter card. In the diploma thesis are discussed all function blocks of the converter card and they are explained in detail. In the thesis are subsequently tested all problem parts of the converter card for the precise control of the laser diode, such as fast switching of the current flowing through the laser diode and design of the connection for evaluating of current pulse from the sensing photodiode. An integral part of thesis is a description of created printed circuit board and there are described all used layers and devices’ layout on the PCB. Final part of the diploma thesis deals with firmware for the microcontroller, which was made for testing of all function blocks of the converter card for the precise control of a laser diode. At the same time was developed software for PC, which communicates with the converter card via universal serial bus (USB).
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Short path optical wireless link design
Kovář, Ondřej ; Látal, Jan (referee) ; Diblík, Jan (advisor)
This diploma thesis is focused on design and prototyping of wireless optical link for an indoor usage. In the beginning of the thesis frequency spectrums of infrared, visible and ultraviolet light are described by its typical qualities such as values of attenuation or reflection capability. On the basis of this analysis, a proper wavelength has been chosen for usage at the engineered communication system. Next part is devoted to selection of suitable communication components on basis of its declared qualities. In the following chapter this qualities are in carefully measured and after that they are compared with values provided by its manufacturer. The following section is devoted to design schemes of transceiver modules. After completion of the design the manufacturing of PCB, mounting components and the analysis of their distribution was described. The last part of this thesis deals with testing of created prototype in terms of maximum transmission distances and operating frequencies. At the very end of this project, in one small section ways to improve system characteristics was discussed.
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Design of measurement unit for analysis of surface materials properties
Kratochvíl, Robert ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
The thesis deals with the application of laser beams for examination of material properties. The properties being examined are quality of surface finish and transmissivity of materials in the optical portion of the electromagnetic spectrum. A measuring device containing laser diodes as a source of laser beam and photodiodes for evaluation of examined phenomena serves for examination of both properties. Conversion of the signal to digital quantity and its further processing take place in a microcontroller. The data is then sent via a serial bus and a converter to a computer, where it may be saved in a user program and where the user can work with them later. The thesis contains results of reflectivity measurement of a set of metal samples with different surface finish. Transmissivity measurement was applied on a set of optical filters.
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Optical connection
Horák, Jaroslav ; Mišurec, Jiří (referee) ; Káňa, Ladislav (advisor)
Master's thesis treat of optical connection. The aim of this work was also the practical implementation and successful testing. Communications signal is low frequency in the range of 20 to 15 kHz and intended length of the coupling is approximately 200 m. The first is the work carried out theoretical analysis issues. Then is described the design and implementation of its own facility. In conclusion, the measurement is done and evaluate the parameters. I have dealt the optical connection with using a laser beam that is modulated frequency modulation. This optical signal is converted in the receiver using a PIN photodiode (type PIN) back to the electrical signal. Then there is the demodulation and amplification. The frequency modulator and demodulator is phase lock loop. It realizes the type of circuit CMOS 4046. The work is designed properly functioning equipment. It serves for the transmission of speech and audio signal line. It has good properties that match the criteria. The connection can be used outdoors due to the use of cover. The scope of communication may be even greater than 200 meters
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