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Design and verification of a feedback control for thermostatized chamber
Fridrich, Martin ; Králík, Jan (referee) ; Řeřucha,, Šimon (advisor)
Temperature variations have a great influence on the accurate length measurement by laser interferometry. An environment with controlled temperature is important to characterize and compensate for these effects. This thesis is concerned with the implementation of feedback control for a test chamber to create this controlled environment. The first part is devoted to a survey of control techniques, the basic principles of laser interferometry, the CANopen communication protocol, and the current design of the thermostatic chamber used at the Department of Coherent Optics of the Institute of Scientific Instruments of the CAS. The next part describes the design of the new chamber, the creation of the control software, the implementation of the control, and its optimization using several methods. Finally, the thesis contains a characterization of the conditions in the chamber. Comparison with the original condition shows more than a twofold improvement in temperature stability and an almost threefold reduction in the environmental influences on the temperature inside of the chamber.
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SMV-2023-63: Measuring interferometric systems
Mikel, Břetislav
The contract research was focused on the development of multi-axis measuring systems using the most accurate method of measurement based on the principle of laser radiation interference. The basic reference is a laser source with a wavelength of 633 nm. Measuring systems are intended for devices requiring measurement accuracy in the order of nanometers.
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SMV-2023-61: Measuring systems for lithographers
Mikel, Břetislav
The contract research was focused on the development of multi-axis measuring systems using the most accurate method of measurement based on the principle of laser radiation interference. The basic reference is a laser source with a wavelength of 633 nm. Measuring systems are intended for devices requiring measurement accuracy in the order of nanometers.
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Surface analysis using low-coherence interferometry
Pikálek, Tomáš ; Novák, Jiří (referee) ; Buchta, Zdeněk (advisor)
This thesis deals with low-coherence interferometry, laser interferometry and its combination intended to be used for contactless surface analysis. It outlines theoretical background of laser interferometry and low-coherence interferometry and describes in detail interference fringe center detection techniques used in low-coherence interferometry and their implementation into MATLAB environment. All these techniques theoretically described were analyzed to evaluate their measurement accuracy, resistance to optical dispersion and computational complexity in order to choose the most appropriate technique to be involved into the experiment. Furthermore, the thesis describes design of an experimental setup for optical surface analysis combining laser interferometry and low-coherence interferometry. There are presented experimental results and its comparison with the reference measurement. Overall measurement uncertainty is calculated and discussed too.
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Analysis and verification of air refractive index measurement method for laser interferometry
Pikálek, Tomáš ; Novák,, Jiří (referee) ; Buchta, Zdeněk (advisor)
This thesis deals with a theoretical analysis and experimental verification of a new method for the refractive index of air measurement. This method uses a combination of laser and low-coherence interferometry. The experimental setup is based on the Michelson interferometer equipped with a double-spaced glass cell. The optical path difference between the inner and outer part of the cell that is proportional to air refractivity is estimated using two low-coherence interference signals. These signals are analysed in the frequency domain which results in the dependence of the phase change caused the by air on vacuum wavelength. This dependency is fitted by a theoretical function based on Edlén's equations in order to calculate the phase difference for laser wavelength. This value is then made more accurate utilising two laser interference signals and used for the air refractive index calculation. The new method was experimentally verified and compared to two different techniques. Moreover, the measurement uncertainty was evaluated.
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Assessment of geometric accuracy of machining center using digital inclinometers
Únar, Jan ; Marek, Tomáš (referee) ; Holub, Michal (advisor)
This diploma thesis deals with assessment of geometric accuracy of machining center MCV 754 QUICK. BlueSYSTEM digital inclinometers from WYLER AG, XL-80 laser interferometer from RENISHAW, Ballbar QC20-W from RENISHAW and LaserTRACER self-guiding laser interferometer from ETALON AG were used to measure accuracy. Error of the X straightness in the direction of the Z axis was assessed. The first part of the paper describes the geometric accuracy of the machine, currently available instruments for measuring geometric accuracy and an explanation of straightness. The second part consists of the design of measurements, experiment, evaluation and comparison of results and recommendations for teaching.
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Advanced Interferometric Methods of Coordinates Measurement
Holá, Miroslava ; Klapetek,, Petr (referee) ; Mrňa, Libor (referee) ; Lazar, Josef (advisor)
This thesis addresses particular topics in the field of the length metrology for nanometrology. Nanometrology deals with dimensional measurements of micro- and nanostructures with a high spatial resolution. It typically combines a microscope imaging with a precise coordinate measurement, usually capable of nanometre resolution using the state-of-art laser interferometry techniques. The development in this field is driven, among others, by emerging advanced nanotechnologies that demand to push further the capabilities and limits of the interferometric techniques to make the nanometre-level dimensional measurement of nanostructures possible. The principal limitations of current systems are the environmental conditions and especially the fluctuations in the refractive index of air. The theoretical part of this thesis aim at analysis of individual parts of laser interferometer. I oriented myself on the study of their advantages/disadvantages and further also the possibilities of their industrial applications. The second part of the thesis presents my work that focused on the influence of the refractive index of air (RIA) on the measurement uncertainty. I experimentally demonstrated an interferometric system with a self-cancellation RIA fluctuations: a transparent photodetector is used for the measurement of the standing wave along the axis of a passive resonator, where the resonator also serves as a reference for the laser wavelength stabilisation. Another optical arrangement, based on a setup of several Michelson interferometers, represents a combination of an interferometer and a refractometer into a single system. This setup was used to study the behaviour of the ambient airflow with respect to the optical path difference and physical separation of the interferometer’s and refractometer’s path. Based on the experimental results I proposed new arrangements for shape measuring interferometers, which combine length interferometry and a tracking refractometer for the direct compensation of RIA fluctuations with geometrically adjacent optical beams. The results indicate an improvement in RIA fluctuation induced uncertainty by a factor of 100. Third part describes the design and implementation of interferometric systems for specific applications. For the industrial environment I developed a compact interferometric displacement gauge which is designed to allow nanometre level measurement using a simplified interferometer construction. For coordinate measurement of the position of the sample up to six degrees of freedom, I realised a compact modular interferometric system, which represents a unique setup together with a stabilised laser source. To measure the position of the sample in an electron beam writer chamber, I designed and implemented a differential interferometer that works in the near infrared domain and uses a new detection method developed for this system. In the fourth part I describe the realisation of a high-speed interferometer with a differential arrangement, which allows evaluation of high-cycle fatigue in material engineering. This method of studying high-cycle fatigue should be beneficial for both the basic research and the engineering practice.
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Uncertainties in interferometric measurements
Kočí, Radek ; Šedivá, Soňa (referee) ; Havlíková, Marie (advisor)
This diploma thesis deals with uncertainties of interferometric measurements and methods for their evaluation. In the theoretical part of the thesis, are described interferometers and interferometric measurement techniques. Furthermore, there is presented process of determining the measurement uncertainty using methods GUM and Monte Carlo. In the practical part of the thesis, there are these two methods are used for qualification of measurement uncertainty calculated for the specific interferometer.
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Characterization and elimination of thermomechanical effects in interferometric length measurement
Řeřucha, Šimon ; Holá, Miroslava ; Lazar, Josef ; Mikel, Břetislav ; Číp, Ondřej
Continuous efforts to develop dimensional measurements at both the nano- and macro-scale continue to present challenges in extending high-precision measurement procedures from the well-controlled experimental environment of a typically single measurement cycle to a constant-load production environment. In the field of laser interferometry, which is both a cornerstone of length metrology in general and an essential part of nanometrology, we have focused on long-term measurement stability (so-called zero-drift) in measurement scenarios and applications based on (mostly laser) interferometry. A well-characterized and compensated measurement zero-drift in such applications becomes more important both with applications in less controlled environments and with increasing measurement timeframes, such as long scans in microscopic nanometrology, long exposures in electron lithography, or interferometric reference calibrations with a larger number of calibration points or repetitions. The goal of the current research effort is to comprehensively investigate error effects and contributions to measurement uncertainty related to zero-drift in laser interferometry-based applications, with a particular focus on temperature effects (as these typically appear to be the dominant contribution) and approaches to suppress them. This effort involves several complementary directions.
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