A5073741121- Optical measurement and interference techniques
- Digital Holography and Microscopy
- Fluid Dynamics and Turbulent Flows
- Advanced Optical Imaging Technologies
- Flow Measurement and Analysis
- Advanced Measurement and Metrology Techniques
- Image Processing Techniques and Applications
- Surface Roughness and Optical Measurements
- Aerodynamics and Acoustics in Jet Flows
- Acoustic Wave Phenomena Research
- Speech and Audio Processing
- Photorefractive and Nonlinear Optics
- Advanced X-ray Imaging Techniques
- Combustion and flame dynamics
- Aeroelasticity and Vibration Control
- Force Microscopy Techniques and Applications
- Plasma and Flow Control in Aerodynamics
- Structural Health Monitoring Techniques
- Thermography and Photoacoustic Techniques
- Microfluidic and Bio-sensing Technologies
- Particle Dynamics in Fluid Flows
- Advanced Fiber Optic Sensors
- Scientific Measurement and Uncertainty Evaluation
- Lattice Boltzmann Simulation Studies
- Ear Surgery and Otitis Media
Technical University of Liberec
2015-2025
Czech Academy of Sciences, Institute of Plasma Physics
2014-2023
Czech Academy of Sciences
2019-2021
Worcester Polytechnic Institute
2019
This paper presents a digital holographic method for measurement of periodic asymmetric temperature fields. The is based on modified Twyman-Green setup having double sensitivity. For only one precisely synchronized and triggered camera used. periodicity self-similarity each cycle the measured phenomenon combined with capture allow to obtain data later used three-dimensional (3D) measurement. reconstruction 3D field tomographic approach.
High-precision measurements of mechanical parts' surface topography represent an essential task in many industry sectors. Examples such tasks are, e.g., precise alignments opto-mechanical systems, large object deformation measurements, evaluation shape, and others. Today, the standard method used for is based on use coordinate measuring machines (CMMs). Unfortunately, CMMs have severe shortcomings: low measurement point density, long time, risk damage, etc. Indeed, time rapidly increases...
The "sonic region" of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity sufficient understand fine scale phenomena that govern quiescent solar corona, as well lead coronal mass ejections (CMEs), which influence space weather. Improvement on this front requires eclipse-like conditions over long observation times. space-borne coronagraphs flown so far provided a continuous coverage external parts but their over-occulting system did not permit analyse...
A high-speed interferometric system was developed to analyze nanostructured porous silicon (PS) membranes by measuring reflectance variations during capillary filling from both sides. camera employed capture the evolution of entire sample area with necessary temporal resolution, providing quantitative information on dynamics. By integrating these data a simple fluid dynamic model, it is possible examine internal structure and determine effective pore radii profiles along their thickness. The...
A method for the measurements of out-ofplane displacement on surface vibrating object is presented herein. This based frequency-shifted timeaveraged digital holographic interferometry, employing principle phase shifting. approach allows significant noise reduction, which results in high sensitivity measurements. makes it possible to measure vibrations with amplitudes nanometer range over whole measured surface. was applied visualization out-of-plane vibration modes piezoelectric...
To improve the understanding of middle-ear hearing mechanism and assist in diagnosis diseases, we are developing a high-speed digital holographic (HDH) system to measure shape acoustically-induced transient displacements tympanic membrane (TM). In this paper, performed measurements on cadaveric human ears with simulated common pathologies. The frequency response function (FRF) normalized displacement by stimulus (sound pressure) at each measured pixel point entire TM surface was calculated...
A novel radius of the curvature measurement method for optical spherical surfaces using absolute interferometry is proposed. setup designed and built around a common-path Fizeau interferometer. The cavity length (volume air between reference tested surfaces) can be measured by wavelength tuning interferometry. An interconnection data from three different tunable laser diodes (central wavelengths 780, 785 852 nm) allows us to measure with uncertainty tens hundreds nanometres. Once...
A technique for measurement of the thickness optical elements using absolute wavelength scanning interferometry is presented in this paper. To achieve high-grade components and systems, both planar non-planar must be measured with an accuracy a few micrometers. The proposed based on Fizeau interferometer interconnects data from three different tunable laser diodes yielding long effective range thus low uncertainty. uncertainty central ranges hundreds nanometers to microns. method allows...
In this paper, we present a method of quantitatively measuring in real-time the dynamic temperature field change and visualization volumetric fields generated by 2D axial-symmetric heated fluid from pulsatile jet water tank through off-axis digital holographic interferometry. A Mach-Zehnder interferometer on portable platform was built for experimental investigation. The submerged fed with higher temperature. Tomographic approach used to reconstruct Abel Transform filtered back-projection....
This paper shows the possibility of measurement a temperature field generated by heated fluid from synthetic jet (SJ) actuator. Digital holographic interferometry (DHI) was main measuring method used for experiments. A single-projection DHI visualization as an average along optical axis. The results are compared with data obtained constant current anemometry (CCA) experiments validation method. Principle 3D distribution using tomographic approach is also described in this paper. single SJ...
In this article, we report on the observation of a ferroelectric domain pattern in whole volume barium titanate single crystal by means digital holographic microscopy (DHM). Our particular implementation DHM is based Mach–Zehnder interferometer and numerical processing data employs angular spectrum method. A modification technique, which allows fast accurate determination walls, i.e. narrow regions separating antiparallel domains, presented. Accuracy sensitivity method are discussed. Using...
The presented paper shows the possibility of digital holographic interferometry application in measurement unsteady 2D temperature field generated by pulsatile flow which is impinging heated surface. Special setup with double sensitivity was developed instead commonly used MachZehnder type interferometer order to attain parameters sufficient for studied case. This not light efficient like but has sensitivity. results from experiments are perfected velocity achieved methods hot-wire anemometry.
The shape of the tympanic membrane (TM) plays an important role in sound transmission through ear for hearing. Previously we developed a high-speed holographic system employing tunable wavelength laser rapid TM measurement. However, illumination was not sufficient to measure unpainted due semi-transparency and short exposure time camera. This paper presents new multiple angle technique that allows us use higher power single perform measurements on TM. Accuracy method is demonstrated by step...
In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, input output impedances were measured for low-power signals. Transformer efficiency transformation ratio as a function of frequency impedance load the secondary circuit....
This paper presents a non-nulling absolute interferometric method for fast and full-area measurement of aspheric surfaces without the necessity any mechanical movement. Several single frequency laser diodes with some degree tunability are used to achieve an measurement. The virtual interconnection three different wavelengths makes it possible accurately measure geometrical path difference between measured surface reference Fizeau independently each pixel camera sensor. It is thus even in...
The applicability of the digital holography to grinded surfaces shape measurements is experimentally examined with regard surface micro-roughness brittle materials (optical glass). Multi-wavelength phase shifted holographic interferometry (holographic contouring) used and its performance analyzed. Holographic contouring a great candidate for precise measurement technique, which can be applied iterative manufacture process optical elements. Optical artifacts different radii spherical (convex...
This paper presents a very effective interference technique for the sensing and researching of compressible fluid flow in wind tunnel facility. The developed is sensitive accurate, yet easy to use under conditions typical aerodynamic labs, will be used nonintrusive investigation flutter blade cascades. interferometer employs high-speed camera, fiber optics, available "of-the-shelf" optics optomechanics. construction together with ensures high compactness portability system. Moreover,...
The auditory system of mammals enables the perception sound from our surrounding world. Containing some smallest bones in body, ear transduces complex acoustic signals with high-temporal sensitivity to mechanical vibrations magnitudes as small tens picometers. Measurements shape and acoustically induced motions different components are essential if we expand understanding hearing mechanisms, also provide quantitative information for development numerical models that can be used improve...
An experimental method for three-dimensional (3D) imaging of ferroelectric domain patterns using digital holographic tomography is presented. The implementation this employs the curvilinear filtered back-projection. Our has been demonstrated on imagining structure in a periodically poled lithium niobate single crystal. developed allows fast and accurate 3D observations structures whole volume crystals millimeter scale.