scholarly journals Lock-in vibration retrieval based on high-speed full-field coherent imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Erwan Meteyer ◽  
Silvio Montresor ◽  
Felix Foucart ◽  
Julien Le Meur ◽  
Kevin Heggarty ◽  
...  
Keyword(s):  
High Speed ◽  
Spatial Scales ◽  
Laser Doppler Vibrometer ◽  
Optical Path Difference ◽  
Frame Rate ◽  
Structural Vibration ◽  
High Speed Imaging ◽  
Coherent Imaging ◽  
Full Field ◽  
Measurement Capability

AbstractThe use of high-speed cameras permits to visualize, analyze or study physical phenomena at both their time and spatial scales. Mixing high-speed imaging with coherent imaging allows recording and retrieving the optical path difference and this opens the way for investigating a broad variety of scientific challenges in biology, medicine, material science, physics and mechanics. At high frame rate, simultaneously obtaining suitable performance and level of accuracy is not straightforward. In the field of mechanics, this prevents high-speed imaging to be applied to full-field vibrometry. In this paper, we demonstrate a coherent imaging approach that can yield full-field structural vibration measurements with state-of-the-art performances in case of high spatial and temporal density measurements points of holographic measurement. The method is based on high-speed on-line digital holography and recording a short time sequence. Validation of the proposed approach is carried out by comparison with a scanning laser Doppler vibrometer and by realistic simulations. Several error criteria demonstrate measurement capability of yielding amplitude and phase of structural deformations.

scholarly journals Lock-in Vibration Retrieval Based on High-speed Full-field Coherent Imaging

2020 ◽  
Author(s):  
Pascal PICART ◽  
Charles PEZERAT ◽  
Erwan METEYER ◽  
Felix FOUCART ◽  
Silvio MONTRESOR ◽  
...  
Keyword(s):  
High Speed ◽  
Spatial Scales ◽  
Laser Doppler Vibrometer ◽  
Optical Path Difference ◽  
Frame Rate ◽  
Structural Vibration ◽  
High Speed Imaging ◽  
Coherent Imaging ◽  
Full Field ◽  
Measurement Capability

Abstract The use of high-speed cameras permits to visualize, analyze or study physical phenomena at both their time and spatial scales. Mixing high-speed imaging with coherent imaging allows recording and retrieving the optical path difference and this opens the way for investigating a broad variety of scientific challenges in biology, medicine, material science, physics and mechanics. At high frame rate, simultaneously obtaining suitable performance and level of accuracy is not straightforward. In the field of mechanics, this prevents high-speed imaging to be applied to full-field vibrometry. In this paper, we demonstrate a coherent imaging approach that can yield full-field structural vibration measurements with state-of-the-art performances. The method is based on high-speed on-line digital holography and recording a short time sequence. Validation of the proposed approach is carried out by comparison with a scanning laser Doppler vibrometer and by realistic simulations. Several error criteria demonstrate measurement capability of yielding amplitude and phase of structural deformations.

scholarly journals Experimental study of the dynamic behaviour of High Performance Concrete (HPC) under tensile loading

2018 ◽  
Vol 183 ◽  
pp. 02043 ◽  
Author(s):  
Bratislav Lukić ◽  
Dominique Saletti ◽  
Pascal Forquin
Keyword(s):  
High Speed ◽  
High Performance ◽  
High Performance Concrete ◽  
Imaging System ◽  
Spall Strength ◽  
High Speed Imaging ◽  
Dynamic Tensile Strength ◽  
Full Field ◽  
Local Point ◽  
Measurement Results

This paper presents the measurement results of the dynamic tensile strength of a High Performance Concrete (HPC) obtained using full-field identification method. An ultra-high speed imaging system and the virtual fields method were used to obtain this information. Furthermore the measurement results were compared with the local point-wise measurement to validate the data pressing. The obtained spall strength was found to be consistently 20% lower than the one obtained when the Novikov formula is used.

scholarly journals A portable smartphone-based laryngoscope system for high-speed vocal cord imaging of patients with throat disorders (Preprint)

2020 ◽  
Author(s):  
Jun Ki Kim ◽  
Youngkyu Kim ◽  
Jungmin Oh ◽  
Seung-Ho Choi ◽  
Ahra Jung ◽  
...  
Keyword(s):  
Image Processing ◽  
Vocal Cord ◽  
High Speed ◽  
High Performance ◽  
Vocal Folds ◽  
Frame Rate ◽  
Endoscopic Imaging ◽  
High Speed Imaging ◽  
Underdeveloped Countries ◽  
Longitudinal Edge

BACKGROUND Recently, high-speed digital imaging (HSDI), especially HSD endoscopic imaging is being routinely used for the diagnosis of vocal fold disorders. However, high-speed digital endoscopic imaging devices are usually large and costly, which limits access by patients in underdeveloped countries and in regions with inadequate medical infrastructure. Modern smartphones have sufficient functionality to process the complex calculations that are required for processing high-resolution images and videos with a high frame rate. Recently, several attempts have been made to integrate medical endoscopes with smartphones to make them more accessible to underdeveloped countries. OBJECTIVE To develop a smartphone adaptor for endoscopes to reduce the cost of devices, and to demonstrate the possibility of high-speed vocal cord imaging using the high-speed imaging functions of a high-performance smartphone camera. METHODS A customized smartphone adaptor was designed for clinical endoscopy using selective laser melting (SLM)-based 3D printing. Existing laryngoscope was attached to the smartphone adaptor to acquire high-speed vocal cord endoscopic images. Only existing basic functions of the smartphone camera were used for HSDI of the vocal folds. For image processing, segmented glottal areas were calculated from whole HSDI frames, and characteristics such as volume, shape and longitudinal edge length were analyzed. RESULTS High-speed digital smartphone imaging with the smartphone-endoscope adaptor could achieve 940 frames per second, and was used to image the vocal folds of five volunteers. The image processing and analytics demonstrated successful calculation of relevant diagnostic variables from the acquired images. CONCLUSIONS A smartphone-based HSDI endoscope system can function as a point-of-care clinical diagnostic device. Furthermore, this system is suitable for use as an accessible diagnostic method in underdeveloped areas with inadequate medical service infrastructure.

Nucleate Boiling From Micro-Machined Surfaces

2003 ◽  
Author(s):  
Adrian M. Holland ◽  
Colin P. Garner
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Imaging System ◽  
Laser System ◽  
Ccd Camera ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Frame Rate ◽  
High Speed Imaging ◽  
Machined Surfaces

This paper discusses the production and use of laser-machined surfaces that provide enhanced nucleate boiling and heat transfer characteristics. The surface features of heated plates are known to have a significant effect on nucleate boiling heat transfer and bubble growth dynamics. Nucleate boiling starts from discrete bubbles that form on surface imperfections, such as cavities or scratches. The gas or vapours trapped in these imperfections serve as nuclei for the bubbles. After inception, the bubbles grow to a certain size and depart from the surface. In this work, special heated surfaces were manufactured by laser machining cavities into polished aluminium plates. This was accomplished with a Nd:YAG laser system, which allowed drilling of cavities of a known diameter. The size range of cavities was 20 to 250 micrometers. The resulting nucleate pool boiling was analysed using a novel high-speed imaging system comprising an infrared laser and high resolution CCD camera. This system was operated up to a 2 kHz frame rate and digital image processing allowed bubbles to be analysed statistically in terms of departure diameter, departure frequency, growth rate, shape and velocity. Data was obtained for heat fluxes up to 60 kW.m−2. Bubble measurements were obtained working with water at atmospheric pressure. The surface cavity diameters were selected to control the temperature at which vapour bubbles started to grow on the surface. The selected size and spacing of the cavities was also explored to provide optimal heat transfer.

Investigation of Auto-Ignition of a Pulsed Methane Jet in Vitiated Air Using High-Speed Imaging Techniques

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
W. Meier ◽  
I. Boxx ◽  
C. Arndt ◽  
M. Gamba ◽  
N. Clemens
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Imaging Techniques ◽  
Frame Rate ◽  
Experimental Arrangement ◽  
Single Shot ◽  
Exhaust Gas ◽  
High Speed Imaging ◽  
Auto Ignition ◽  
Flow Field Characteristics

An experimental arrangement for the investigation of auto-ignition of a pulsed CH4 jet in a coflow of hot exhaust gas from a laminar lean premixed H2/air flame at atmospheric pressure is presented. The ignition events were captured by high-speed imaging of the OH∗ chemiluminescence associated with the igniting flame kernels at a frame rate of 5 kHz. The flow-field characteristics were determined by high-speed particle image velocimetry and Schlieren images. Furthermore, high-speed imaging of laser-induced fluorescence of OH was applied to visualize the exhaust gas flow and the ignition events. Auto-ignition was observed to occur at the periphery of the CH4 jet with high reproducibility in different runs concerning time and location. In each measurement run, several hundred consecutive single shot images were recorded from which sample images are presented. The main goals of the study are the presentation of the experimental arrangement and the high-speed measuring systems and a characterization of the auto-ignition events occurring in this system.

Performances and Limitations of Three Ultra High-Speed Imaging Cameras for Full-Field Deformation Measurements

2011 ◽  
Vol 70 ◽  
pp. 81-86 ◽  
Author(s):  
Fabrice Pierron ◽  
Rachid Cheriguene ◽  
Pascal Forquin ◽  
Raphael Moulart ◽  
Marco Rossi ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Grid Method ◽  
Image Correlation ◽  
High Speed Imaging ◽  
Full Field ◽  
Ultra High Speed ◽  
Ultra High Speed Imaging ◽  
Deformation Measurements

This paper compares the technology and the performances of three ultra high speed cameras for full-field deformation measurements with Digital image correlation or the grid method. The three cameras are based on multiple CCD sensors (Cordin 550-62, with rotating mirror or DRS IMACON 200 with gated intensified CCDs) or dedicated chip (Shimadzu HPV). The advantages and limitations of these cameras are critically reviewed.

Nanomanipulator Based on a High-Speed Atomic Force Microscopy

2012 ◽  
Vol 516 ◽  
pp. 396-401
Author(s):  
Itsuhachi Ishisaki ◽  
Yuya Ohashi ◽  
Tatsuo Ushiki ◽  
Futoshi Iwata
Keyword(s):  
Atomic Force Microscopy ◽  
Real Time ◽  
High Speed ◽  
Imaging Technique ◽  
Frame Rate ◽  
High Speed Imaging ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Short Time

We developed a real-time nanomanipulation system based on high-speed atomic force microscopy (HS-AFM). During manipulation, the operation of the manipulation is momentarily interrupted for a very short time for high-speed imaging; thus, the topographical image of the fabricated surface is periodically updated during the manipulation. By using a high-speed imaging technique, the interrupting time could be much reduced during the manipulation; as a result, the operator almost does not notice the blink time of the interruption for imaging during the manipulation. As for the high-speed imaging technique, we employed a contact-mode HS-AFM to obtain topographic information through the instantaneous deflection of the cantilever during high-speed scanning. By using a share motion PZT scanner, the surface could be imaged with a frame rate of several fps. Furthermore, the high-speed AFM was coupled with a haptic device for human interfacing. By using the system, the operator can move the AFM probe into any position on the surface and feel the response from the surface during manipulation. As a demonstration of the system, nanofabrication under real-time monitoring was performed. This system would be very useful for real-time nanomanipulation and fabrication of sample surfaces.

High Speed Imaging of the Fragmentation of the Jules Verne Automated Transfer Vehicle

2009 ◽  
Author(s):  
C. G. Giannopapa ◽  
J. Hatton ◽  
E. Franken ◽  
B. van der Linden ◽  
P. Jenniskens
Keyword(s):  
Time Use ◽  
High Speed ◽  
Space Station ◽  
Frame Rate ◽  
Wide Field ◽  
High Speed Imaging ◽  
High Frame Rate ◽  
Jules Verne ◽  
Rendezvous And Docking ◽  
Field View

The Automated Transfer Vehicle (ATV) “Jules Verne” is the first completely automated rendezvous and docking spaceship to service to the International Space Station (ISS). As a cargo ship, it is designed for one-time use. After completing its mission, it is subjected to hypersonic flow during the re-entry into earth’s atmosphere, with high associated heat flux leading to structural heating and fragmentation of the vehicle. During its first voyage on September 29, 2008, the ATV reentry was observed using various instruments including a wide field view camera and high frame rate cameras. Using the wide field view camera the trajectory path can be reconstructed. The high frame rate camera gives information about the sequence of the events of the explosions and fragmentations of various parts of the spacecraft. The aim of this paper is to present the detailed events that occurred during the ATV re-entry.

Static and Dynamic Deformation Measurements of Micro Beams by the Technique of Digital Image Correlation

2006 ◽  
Vol 326-328 ◽  
pp. 211-214 ◽  
Author(s):  
Xiao Yuan He ◽  
Wei Sun ◽  
Xiang Zheng ◽  
Meng Nie
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Dynamic Deformation ◽  
Full Range ◽  
Frame Rate ◽  
Image Correlation ◽  
Static Tests ◽  
Full Field ◽  
Fringe Patterns ◽  
Vibration Parameters

It is critical to measure the static and dynamic deformation of the micro beam over their full range of voltage and frequency inputs, which are key parameters for predicting device behavior. In this study, full-field technique by correlation of projected fringe patterns is selected to determine static deformation, while dynamic parameters can be obtained by DIC with high-speed CMOS camera, whose maximal frame rate is 32k f/s. The static tests of micro beams are carried out by applying electric field forces under different dc voltage, while the dynamic tests are excited by harmonic excitations. Using the DIC method, the whole field in-plane or out-of-plane displacements of the micro beams are obtained, and hence the dynamic characteristics by post-processing of vibration analysis. Experimental results including the bending deformation and vibration parameters are reported and compared with finite element method. This study verifies the feasibility of this technique to measure both static and dynamic characteristics of MEMS components.

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