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Michelson's interferometer
Rýc, Jan ; Klusáček, Stanislav (referee) ; Havránek, Zdeněk (advisor)
The diploma work deals with techniques of optical contactless distance and velocity measurement. A basic summary of the methods are involved. The problematic of interferometric methods for vibration measurements is analysed in detail. It contains division of interferometers, description of their function principles and also chapters dealing with elements used in interferometers such as lasers, photodetectors and elements in the ray optical way - polarizers, retarders, optical isolators. The vibration and length measurement methods are described, as well as the conception of homodyne and heterodyne detection. Part of this work focuses on the quadrature signal processing and on the proposal of algorithm for demodulation of velocity/displacement and undergoing simple motioning object deviation. This algorithm is implemented in Labview and the whole software instrument served also for visualisation of measured data of the interferometer model constructed in the laboratory. The way how to build up a model, its setting and two possible configurations suitable for homodyne detection are described. Model of interferometer is built-up on the optical breadboard. Particular components are fixed by the help of mounts. The model and software enable to measure the velocity and the vibration deviation with the light wavelength exactness. Functionality and the exactness of the laboratory model are verified by vibrometer. Effects on the measurement uncertainty are discussed here and ways how to restrain them are proposed.
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Optical fiber sensor based on Michelson interferometer
Kopáč, Ondřej ; Grenar, David (referee) ; Čučka, Milan (advisor)
This bachelor thesis deals with description and simulation of Michelson unbalance interferometer and description of fiber optic sensors. The simulation is realized by MatLab. The thesis also described basic optical phenomena, types of optical fibers and two types of interferometric detection. The thesis also deals with description of measurements and their results.
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Atmospheric correction unit for the laser interferometer
Kučera, Stanislav ; Drexler, Petr (referee) ; Szabó, Zoltán (advisor)
This work deals with design, realization and testing the device for suppression the effect of the fluctuation of the atmospheric conditions on the laser interferometer measurement. Parasitic and randomly changes of atmospheric conditions – temperature, pressure, relative humidity and chemical composition of the air changes his refractive index, then wavelength of the laser light in this environment. Physical properties of air are measured by ultraprecision sensors. The actual wavelength is periodically calculated from Edlén formula. The device is processing the quadrature output signals from receiver of the homodyne interferometer include the atmospheric correction in real time. The device is equipped with interface to data acquisition into the personal computer.
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Optical fiber sensor based on Michelson interferometer
Kopáč, Ondřej ; Grenar, David (referee) ; Čučka, Milan (advisor)
This bachelor thesis deals with description and simulation of Michelson unbalance interferometer and description of fiber optic sensors. The simulation is realized by MatLab. The thesis also described basic optical phenomena, types of optical fibers and two types of interferometric detection. The thesis also deals with description of measurements and their results.
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Atmospheric correction unit for the laser interferometer
Kučera, Stanislav ; Drexler, Petr (referee) ; Szabó, Zoltán (advisor)
This work deals with design, realization and testing the device for suppression the effect of the fluctuation of the atmospheric conditions on the laser interferometer measurement. Parasitic and randomly changes of atmospheric conditions – temperature, pressure, relative humidity and chemical composition of the air changes his refractive index, then wavelength of the laser light in this environment. Physical properties of air are measured by ultraprecision sensors. The actual wavelength is periodically calculated from Edlén formula. The device is processing the quadrature output signals from receiver of the homodyne interferometer include the atmospheric correction in real time. The device is equipped with interface to data acquisition into the personal computer.
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Michelson's interferometer
Rýc, Jan ; Klusáček, Stanislav (referee) ; Havránek, Zdeněk (advisor)
The diploma work deals with techniques of optical contactless distance and velocity measurement. A basic summary of the methods are involved. The problematic of interferometric methods for vibration measurements is analysed in detail. It contains division of interferometers, description of their function principles and also chapters dealing with elements used in interferometers such as lasers, photodetectors and elements in the ray optical way - polarizers, retarders, optical isolators. The vibration and length measurement methods are described, as well as the conception of homodyne and heterodyne detection. Part of this work focuses on the quadrature signal processing and on the proposal of algorithm for demodulation of velocity/displacement and undergoing simple motioning object deviation. This algorithm is implemented in Labview and the whole software instrument served also for visualisation of measured data of the interferometer model constructed in the laboratory. The way how to build up a model, its setting and two possible configurations suitable for homodyne detection are described. Model of interferometer is built-up on the optical breadboard. Particular components are fixed by the help of mounts. The model and software enable to measure the velocity and the vibration deviation with the light wavelength exactness. Functionality and the exactness of the laboratory model are verified by vibrometer. Effects on the measurement uncertainty are discussed here and ways how to restrain them are proposed.
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Interferometric measurement system for cost effective e-beam writer
Řeřucha, Šimon ; Šarbort, Martin ; Lazar, Josef ; Číp, Ondřej
The reliability of nanometer track writing in the large scale chip manufacturing process depends mainly on a precise positioning of the e-beam writer moving stage. The laser interferometers are usually employed to control this positioning, but their complicated optical scheme leads to an expensive instrument which increases the e-beam writer’s manufacturing costs. We present a new design of an interferometric system useful in a currently developed cost effective e-beam writers. Our approach simplifies the optical scheme of known industrial interferometers and shifts the interference phase detection complexity from optical domain to the digital signal processing part. Besides the effective cost, the low number of optical components minimizes the total uncertainty of this measuring instrument. The scheme consists of a single wavelength DFB laser working at 1550 nm, one beam splitter, measuring and reference reflectors and one photo-detector at the interferometer output. The DFB laser is frequency modulated by slight changes of injection current while the interference intensity signal is processed synchronously. Our algorithm quantifies the phase as two sinusoidal waveforms with a phase offset equal to the quarter of the DFB laser wavelength. Besides the computation of these quadrature signals, the scale linearization techniques are used for an additional suppression of optical setup imperfections, noise and the residual amplitude modulation caused by the laser modulation. The stage position is calculated on basis of the DFB laser wavelength and the processed interference phase. To validate the precision and accuracy we have carried out a pilot experimental comparison with a reference interferometer over the 100 mm measurement range. The first tests promise only 2 nm deviation between simplified and the reference interferometer.
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Interferometric Displacement Measurement with Frequency Modulated Beam
Řeřucha, Šimon
In this paper, we describe a new detection method, based on the traditional homodyne detection. The focus of the new method consists in using a frequency-modulated laser source for extracting phase information with similar accuracy. Unlike the original techniques the new method does not require to use polarizing optics in the interferometer itself, and only one photodetector is sufficient for the evaluation.
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