High speed electronic speckle pattern interferometry as a method for studying the strike on a steelpan.

2011 ◽  
Vol 129 (4) ◽  
pp. 2615-2615
Author(s):  
Andrew C. Morrison ◽  
Thomas R. Moore ◽  
Daniel Zietlow
Keyword(s):  
High Speed ◽  
Speckle Pattern ◽  
Electronic Speckle Pattern Interferometry

Phase Algorithm Integrating Direct-Correlation and Four-Step Phase-Shifting for Electronic Speckle Pattern Interferometry

2013 ◽  
Vol 448-453 ◽  
pp. 3696-3701
Author(s):  
Yan Bin He ◽  
Xin Zhong Li ◽  
Min Zhou
Keyword(s):  
High Speed ◽  
Speckle Pattern ◽  
Phase Shifting ◽  
Electronic Speckle Pattern Interferometry ◽  
High Speed Camera ◽  
Dynamic Measurements ◽  
High Quality ◽  
Correlation Algorithm ◽  
Phase Map

A phase-shifting algorithm, called a (4,4) algorithm, which takes four phase-shifting interferograms before a specimen is deformed and four interferograms after a specimen is deformed, is presented first. This method is most widely used for phase extraction. Its drawback limited it to be used in dynamic measurements. Also shown is an algorithm called a (4,1) algorithm that takes four phase-shifting interferograms before a specimen is deformed and one interferogram after a specimen is deformed. Because a high-speed camera can be used to record the dynamic interferogram of the specimen, this algorithm has the potential to retain the phase-shifting capability for ESPI in dynamic measurements. The quality of the phase map obtained using (4,1) algorithm is quite lower compared to using (4,4) algorithm. In order to obtain high-quality phase map in dynamic measurements, a direct-correlation algorithm was integrated with the (4,1) algorithm to form DC-(4,1) algorithm which is shown to improve significantly the quality of the phase maps. The theoretical and experimental aspects of this newly developed technique, which can extend ESPI to areas such as high-speed dynamic measurements, are examined in detail.

A study of brake disc modal behaviour during squeal generation using high-speed electronic speckle pattern interferometry and near-field sound pressure measurements

2000 ◽  
Vol 214 (3) ◽  
pp. 285-296 ◽  
Author(s):  
M Reeves ◽  
N Taylor ◽  
C Edwards ◽  
D Williams ◽  
C. H. Buckberry
Keyword(s):  
High Speed ◽  
Sound Pressure ◽  
Surface Deformation ◽  
Speckle Pattern ◽  
Near Field ◽  
Electronic Speckle Pattern Interferometry ◽  
Brake Disc ◽  
Pressure Measurements ◽  
Near Field Sound ◽  
Field Sound

The out-of-plane surface vibration of a brake disc during naturally excited squeal has been investigated using a combination of high-speed electronic speckle pattern interferometry (ESPI) and near-field sound pressure measurements. Both techniques provide visualization and quantification of the time-resolved surface velocity. A mathematical description of disc brake squeal modal behaviour is proposed that predicts accurately all of the experimentally observed interferometry and sound field measurements. The complex mode description proposed here is in agreement with that proposed by others for drum brake squeal. This assumes that two identical diametral modes are excited simultaneously, identical except for a spatial and temporal phase shift. The use of a near-field microphone array provided a convenient multipoint, non-contacting vibration probe which may find use in the study of other vibrations characterized by high surface amplitudes and efficient sound radiation. The high-speed ESPI provided a real-time visualization of surface deformation analogous to double- pulsed holographic interferometry, with the benefit of giving a true time series of the surface deformation during a single vibration cycle.

Full-Field Laser Vibrometer for Instantaneous Vibration Measurement and Non-Destructive Inspection

2010 ◽  
Vol 437 ◽  
pp. 407-411 ◽  
Author(s):  
James M. Kilpatrick ◽  
Vladimir B. Markov
Keyword(s):  
High Speed ◽  
Fiber Optic ◽  
Speckle Pattern ◽  
Vibration Measurement ◽  
Electronic Speckle Pattern Interferometry ◽  
Laser Vibrometer ◽  
Full Field ◽  
The Matrix ◽  
Interferometric Sensor ◽  
Non Destructive

We describe a system for real-time, full-field vibrometry, incorporating features of high-speed electronic speckle pattern interferometry (ESPI) and laser Doppler velocimetry (LDV). Based on a 2D interferometric sensor array, comprising 16×16 parallel illumination and detection channels, the matrix laser vibrometer (MLV), captures full-field data instantaneously, without beam scanning. The instrument design draws on the advantages of scale offered by modern telecommunications fiber optic and digital electronics. The resulting architecture, comprising a compact measurement probe linked by fiber optic umbilical to a remote electronics unit, facilitates practical application to the full-field study of transient vibrations and rapid non-destructive inspection of composite materials.

Dynamic Holographic-Electronic Speckle-Pattern Interferometry

1993 ◽  
Vol 60 (4) ◽  
pp. 866-874 ◽  
Author(s):  
M. A. Ahmadshahi ◽  
Sridhar Krishnaswamy ◽  
S. Nemat-Nasser
Keyword(s):  
High Speed ◽  
Speckle Pattern ◽  
Processing System ◽  
Ccd Camera ◽  
Electronic Speckle Pattern Interferometry ◽  
Relative Deformation ◽  
Full Field ◽  
Speckle Patterns ◽  
Fringe Patterns ◽  
Laser Light Source

The development of a nondestructive, full-field, quantitative optical technique, and its feasibility to study dynamic deformations of opaque and diffusively reflecting solids under transient loads, are discussed. The technique involves recording a sequence of dynamically changing two-beam speckle interference patterns (also called holographic speckle patterns) of a rapidly deforming body which is doubly illuminated by a laser light source. The time sequence of speckle patterns is recorded by means of a high-speed camera on an ultra-sensitive 35-mm film. The developed negatives are then digitized by a CCD camera into an image processing system. An initial speckle pattern corresponding to the undeformed state of the object is taken as the reference, and subsequent speckle patterns are digitally subtracted (reconstructed) from it to produce time- varying fringe patterns corresponding to the relative deformation of the test object. In order to gain confidence that the technique can be used to record truly transient deformation, it is tested here on a vibrating plate at resonance, thereby obtaining the evolution of the fringe pattern during 1/2 cycle of deformation corresponding to 160 μs.

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