ORIGINAL_ARTICLEThe mid-spatial frequency errors, surface defects arising from the production of optical aspherical surfaces may be a major problem, for example in high-performance systems. At the production of aspherical surfaces on the Optotech MCG100, vibration measurements were performed in various operating modes. The measurement was done with VibXpert II. This device uses piezoelectric sensors to record vibration acceleration. The measurement data were then processed in Matlab software. The aim was to identify frequencies, which may have a negative influence on optical element manufacturing, and also to outline possible causes of their origin. In the observed spectrum (30-800 Hz), significant frequencies from several basic sources were found. This is the tool spindle rotation, tool rotation, the axes control loop, and the movement of the axes themselves.https://acc-ern.tul.cz/archiv/PDF/ACC_2018_1_01.pdf2018-06-3071610.15240/tul/004/2018-1-001VibrationMiddleFrequencyOpticalAsphericSurfaceJiříBeneš1AUTHORMichalŠpína2AUTHORFrantišekProcháska3AUTHOR

ORIGINAL_ARTICLEMeasuring transmittance in the so-called vacuum ultraviolet (UV) region, namely between 160 and 190 nm, is of interest for a range of materials (UV optical glasses and coatings, diamond, thin polymer films, etc.). However, both the necessity to carry out the measurement in vacuum and the need for specific UV-designed optical elements lead to the fact that the vacuum UV spectrometers are rather rare. Here we present construction of a home-made transmission vacuum UV spectrometer. It is based on a Seya-Namioka monochromator and enables us to determine transmittance of flat optical samples in the spectral range of 160 nm- 600 nm with a spectral resolution below 2 nm. We also outline future upgrade of the setup, which will highly improve its parameters.https://acc-ern.tul.cz/archiv/PDF/ACC_2018_1_02.pdf2018-06-30172310.15240/tul/004/2018-1-002Ultraviolet spectrometerTransmission spectrometerSeya-Namioka monochromatorJiříHlubuček1AUTHORJiříBudasz2AUTHORJanVáclavík3AUTHORKarelŽídek4AUTHOR

ORIGINAL_ARTICLEWe provide a review of hyperspectral imaging in infrared region as well as simulation of measurements and reconstructions of test datacubes using the compressed sensing method CASSI (Coded Aperture Snapshot Spectral Imaging). We simulate the presence of the chemical compounds on parts of the image and then we reconstruct its absorption spectrum and localization back from a single snapshot. In other words, we prove that in principle it is possible to reconstruct a sparse 3D datactube from a single 2D dataset. Furthermore, we discuss the quality of the reconstructed data and limitations of the chosen simulation method.https://acc-ern.tul.cz/archiv/PDF/ACC_2018_1_03.pdf2018-06-30243210.15240/tul/004/2018-1-003Hyperspectral imagingInfrared spectrumSpectroscopyCompressed sensingJiříHlubuček1AUTHORKarelŽídek2AUTHOR

ORIGINAL_ARTICLEThis paper presents a novel method for amplitude distribution measurement of harmonically oscillating objects called time average scanning digital holography (TASDH). Reconstructed intensity image from time averaged digital hologram has the form of a set of fringes that follow a zero-order Bessel function of the first kind. When the phase of light beam in the interferometer is modulated, the bright zero-order fringe shifts with respect to the modulation depth. The method is based on continuous shift of the zero-order fringe over the object surface and the value of vibration amplitude is evaluated independently in every single pixel. An advantageous feature of the proposed technique with respect to other digital holographic vibrometry methods is the ability to measure amplitudes of vibration without the risk of interference fringe order, or 2π, errors. On that account, the method allows to measure high slopes amplitudes distribution or discontinuous/partially shaded objects. The correctness of the method was experimentally verified by measuring the bending piezo actuator.https://acc-ern.tul.cz/archiv/PDF/ACC_2018_1_04.pdf2018-06-30334210.15240/tul/004/2018-1-004Digital holographyTime-average holographyScanning holographyVibrationsPhase modulationPavelPsota1AUTHORVítLédl2AUTHORRomanDoleček3AUTHOROndřejMatoušek4AUTHORJanKredba5AUTHOR

ORIGINAL_ARTICLEThis article describes the measuring equipment which is used in the objective evaluation of pianos. This equipment in the form of a play-bench replays each key of the piano keyboard separately, making it possible to measure the acoustics such as sound pressure level and tone reverberation length. Objective evaluation of such a complicated instrument as the piano is a very complex task. An integral part of evaluation is the psychoacoustic dimension and the conversion of subjective perceptions into objective acoustical values.https://acc-ern.tul.cz/archiv/PDF/ACC_2018_1_05.pdf2018-06-30435110.15240/tul/004/2018-1-005PianoPlay-benchStriking pinsAcousticsPsychoacousticsUrbánkováJana1AUTHOR

ORIGINAL_ARTICLEThis article describes a total run-out measurement of a multistart worm which is pressed on a rotor shaft of an electric motor. The measurement is realized by a laser line triangulation sensor during the motor's running. The total run-out evaluation is executed for each spiral of the worm on its addendum circle along the whole length of the worm.https://acc-ern.tul.cz/archiv/PDF/ACC_2018_1_06.pdf2018-06-30536010.15240/tul/004/2018-1-006Total run-outLaser line triangulation sensorMultistart wormProšekAlexander1AUTHOR

ORIGINAL_ARTICLEMost temperate European meadows and pastures belong to semi-natural and temporarily sown intensive grasslands. Semi-natural, mostly rich grasslands species have been maintained by agriculture activities for centuries. However, intensive grasslands are a more modern but widespread phenomenon nowadays. Livestock grazing is the key management for pastures and regular cutting for meadows. A combination of grazing and cutting is typical for grazed meadows. The absence of grassland defoliation, extensification and too intensive management can lead to a decline in plant species diversity resulting in disappearance of endangered plant species. Decreasing of grassland diversity in natural habitats is one of key problems in present nature protection on both sides of Czech (CZ) / German (D) border. In the transboundary region comprising the Jizerské hory Mts (CZ), the Lužické hory Mts (CZ) and the Zittauer Gebirge Mts and foreland (D), twelve manipulative management experiments were established in DiverGrass project on different types of grasslands in order to find optimal measures for stopping declining or increasing of plant species diversity in grasslands habitats.https://acc-ern.tul.cz/archiv/PDF/ACC_2018_1_07.pdf2018-06-30618010.15240/tul/004/2018-1-007GrasslandManagementGrazingCuttingBiodiversityNature protectionJanTitěra1AUTHORHenningHaase2AUTHORTeowdroes KassahunTeka3AUTHORChukwudiNwaogu4AUTHORKláraPavlů5AUTHORMatthiasKändler6AUTHORLenkaPavlů7AUTHORJanGaisler8AUTHORFrantišekPaška9AUTHORHeikeHeidenreich10AUTHORGerlindeLiepelt11AUTHORIrenaJonášová12AUTHORVilemPavlů13AUTHOR