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Measurement of real-time gigacycle fatigue through real-time interferometry
Lazar, Josef ; Holá, Miroslava ; Hrabina, Jan ; Číp, Ondřej
We present an interferometric method for measurement of strain induced deformation of metal samples in experiments inducing high-cycle fatigue. The motivation is to get real-time information about the deformation of a metal sample under test, its elongation imposed by fast vibrating actuator. Fatigue of materials is a process of degradation of a material due to repeated application of forces which includes nucleation and propagation of cracks and leads to the failure of the component. It may appear in all parts of machines or structures which rotate, vibrate, are repeatedly loaded, are subjected to temperature gradients etc., so statistically, fatigue is implied in about 80% of all industrial failures.
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Optical diagnostic methods for energetics
Hrabina, Jan
This work is oriented to non-contacting laser spectroscopy diagnostic methods for monitoring of combustion processes in coal power plant facilities. These methods can be used for optimalization of combustion process in the chamber, which is neccessary step toward reduction of toxic gases releasing in to the atmosphere, increasing of efficiency of the combustion and reduction of overall costs needed for electricity production.
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Coordinate interferometric system for measuring the position of a sample of the electron lithograph
Holá, Miroslava ; Lazar, Josef ; Čížek, Martin ; Řeřucha, Šimon ; Číp, Ondřej
This project is called "Platform of advanced microscopic and spectroscopic techniques for nano and microtechnology." The coordinator of this project is the Brno University of Technology / Faculty of Mechanical Engineering and the co-investigators are ON Semiconductor Czech Republic, Ltd., Optaglio Ltd., Tescan Brno, Ltd. And the Institute of Scientific Instruments of the CAS, v. v. i.. In this project we are working on a design of an interferometric measuring system, laser source and detection techniques for a coordinate measuring system of the table of the electron beam lithography.
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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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Station for LIDT tests of optical components under cryogenic conditions
Oulehla, Jindřich
In this contribution we present a technology for deposition and testing of interference coatings for optical components designed to operate as in power pulsed lasers. We designed and are building a testing apparatus which will serve as an addition to our existing optical coating production facility. This allows us to prepare a coating which is then tested and the results might be used to optimize it. The test samples are placed in a vacuum chamber, cooled down to approximately 120K and Illuminated by a pulsed laser to determine laser damage threshold of the coatings under conditions similar to real life operation. Optical microscopy and spectrophotometer measurements are used for coating investigation after the conducted experiments.
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Laser standards for interferometry and stable frequencies distribution
Hrabina, Jan
Optical frequency references - absorption cells - represent an unique tool for frequency stabilization of the laser sources. Their spectral properies define overall quality of the stabilized laser, so these properties must be precisely controlled and verified. One of the most used absorption media in the visible spectral range is molecular iodine. It offers wide and reach spectra of very narrow and strong transitions so many types of laser standards can be realized on base of this media. Testing of final properties of iodine absorption cells is traditionaly based on two methods - laser induced fluorescence method (LIF) and evaluation of absolute frequency shifts of the iodine stabilized laser (beatnote measurement). Unfortunately both of these methods have few limitations and disadvantages - in case of high-quality cells the LIF method reaches its resolution limits, the beatnote method needs quite complicated optical setup. We present a novel approach for the iodine cells quality evaluation based on measurement of hyperfine transition linewidths - the impurities in absorption media cause line broadening of the transitions. Pilot measurement shows that presented method achieves a very good sensitivity to the iodine purity and together with a need of relatively simple setup can be considered as a novel method for absorption cells quality verification.
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Study of behavior of the refractive index fluctuations to the lenght noise in displacement interferometry
Holá, Miroslava
Nanoscale measurement became one of the key challenges in the field of metrology in last ten years. The international project launched called “Nanotrace” where renowned EU laboratories including the proposer of this project were trying to break the limits of resolution in interferometry. Techniques investigated here have proven that there are chances to achieve significant improvements in resolution of laser interferometry. Measurement of position within a limited range is typical for coordinate measuring system such as nanometrology standards combining scanning probe microscopy (SPM) with precise positioning. In this contribution we evaluate the level of uncertainty associated with spatial shift of two measuring beams and spatial shift of one measuring beam (change of length the measuring beam). Consequently the nature of the fluctuations of the refractive index of air in laser interferometry is investigated anddiscussed with the focus on potential applications in coordinate measuring systems and long-range metrological scanning pro microscopy systems.
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Advanced Laser Measuring Systems in Nanometrology
Lazar, Josef ; Hrabina, Jan ; Holá, Miroslava ; Vychodil, M.
We present a development of a nanometrology system combining local probe microscopy and precise positioning and measuring in the nanoscale. The positioning operates in short range with a focus on precision; displacement measurement controls the sample stage in six degrees of freedom with high-resolution interferometry. The system is designed to operate as a national standard for nanometrology. The contribution presents collaborative work with Meopta company.
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