Change search
ReferencesLink to record
Permanent link

Direct link
A pulsed TV holography system for the study of transients in experimental mechanics
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
2000 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

An all-electronic system for pulsed holographic interferometry called pulsed TV holography is developed. This is a whole-field non-contacting optical measurement method suitable for studies of transient events like wave propagation in solids and fluids. Chemical wet processing of holographic film and optical reconstruction of holograms are no longer needed. The technique was first developed using a double pulsed ruby laser as light source. The holograms are recorded directly on a CCD-detector. Quantitative data of changes in optical path length, caused either by a deformation of a solid object or a change in refractive index in a fluid, are calculated directly in a computer. The system for pulsed TV holography has recently been further developed by the purchase of a new pulsed laser (twin cavity, injection seeded pulsed Nd:YAG) and a CCD camera (PCO Sensicam) with higher spatial resolution and dynamic range. In the survey of this thesis the increased versatility compared to a ruby laser based system is discussed. During the development of the pulsed TV holography system a number of experiments in mechanics and acoustics have been accomplished. Bending waves in impacted plates propagating at a speed of about 2000 m/s are easily “frozen” due to the short duration laser pulses (<30 ns). These waves act as supersonic travelling acoustic sources and generate sound waves in the surrounding air. For the first time, transient sound fields from impacted plates have been visualised and measured using pulsed holographic interferometry. In another experiment, we have demonstrated that the pulsed TV holography system is feasible in combination with tomography. By recording a three-dimensional acoustic pressure field from a number of viewing directions followed by a tomographic reconstruction, the pressure in any point can be calculated. Finally, a method to restore fringes lost by large bulk motions is proposed. This technique may become very attractive in the study of vibrations (preferable transient) on moving or rotating objects. In conclusion, pulsed TV holography is proved to be a fast and reliable method to quantitatively study transients in mechanics and acoustics. The technique has a great potential in experimental mechanics in the future.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2000. , 36 p.
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544 ; 2000:33
Research subject
Experimental Mechanics
URN: urn:nbn:se:ltu:diva-18714Local ID: 9fa8ccf0-7651-11db-962b-000ea68e967bOAI: diva2:991725
Godkänd; 2000; 20061116 (haneit)Available from: 2016-09-29 Created: 2016-09-29Bibliographically approved

Open Access in DiVA

fulltext(54954 kB)7 downloads
File information
File name FULLTEXT01.pdfFile size 54954 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Gren, Per
By organisation
Fluid and Experimental Mechanics

Search outside of DiVA

GoogleGoogle Scholar
Total: 7 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 9 hits
ReferencesLink to record
Permanent link

Direct link