Design of a model of a sensor based on the Shape from focus method is presented. The model uses polychromatic point spread functions of a generalized aperture function of lens and their convolution with an ideal image. The model approaches the reality and allows one to employ parameters of real components of the corresponding sensor, e.g. a spectrum of a light source, a dispersion function of a real imaging optical system and spectral sensitivity of a real light sensitive sensor. The model enables to study accuracy and reliability of the determination of the object’s surface topography by means of the Shape from focus method.
In this contribution the fractal speckle effect is simulated by means of a modification of the proposed numerical model of propagation of ordinary speckle effect. The modification is based on an illumination of a rough object surface by a diffractal – a wave diffracted on an amplitude fractal transparent. The correlation properties of simulated fractal speckle propagated in free space at various angles of observation are investigated with regard to a fractal dimension of the amplitude transparent.
There is presented a simulation of the speckle propagation by means of a computer in this paper. The model is designed
for in-plane translation of an object generating speckle field. There is used the Fresnel-Kirchhof diffraction theory for
description of the speckle field propagation. The presented numerical model involves detection of speckle pattern at any
observation angles. The model is verified through a method of correlation of speckle fields which results are compared to
ones provided by theoretical relations.
This paper describes the use of a speckle correlation method for measurement of object velocity. A basic concept of the measurement method is presented briefly. Relations valid for propagation of speckle fields in the image field between the speckle motion and the object displacement are mentioned. An experimental arrangement for the measurement of in plane object velocity including its possible measurement resolution and accuracy is analyzed. Obtained experimental results are shown, too.
The paper demonstrates possibility of application of the method called speckle pattern correlation for topography of the object surface under investigation. Scanning speckle pattern originating from different points of the object surface illuminated with laser beam enables to get information on height profile of the object surface in these points. This is presented on the measurement of the slope of the object surface. The principle of the presented method is shortly described including necessary equations. A possible optical set-up for the measurement of the slope of the object under investigation is designed and acquired results are presented in comparison with theoretic values.
In this paper we present an optical method based on speckle pattern correlation for measurement of the topography of a surface of an object under investigation. When this object is illuminated with coherent laser beam the arising speckle pattern bears information about the height profile of the object. The resolution of this method is influenced by geometrical parameters of optical measurement set-up. The designed experimental set-up for the measurement of the slope of the object with rough surface is described. Achieved results are presented in comparison with theoretic values.
This paper analyzes the usage of the Yamaguchi's method, so-called the speckle pattern decorrelation, for determination of small static and dynamic object translations. At first the philosophy of the method is presented briefly. Then relationships between the cross correlation function and the small deformation tensor for the case of optically free space and image field are mentioned. Next, different experimental arrangements for the measurement of in-plane and normal
object translations are analyzed. Possible measurement ranges and sensitivities for each arrangement are discussed, too. Finally, some results of our experiments are shown.
The relatively new optical method for the noncontact measurement of the small deformation tensor components of an elementary area of the object surface by means of the theory of the so-called speckle pattern decorrelation is presented. Firstly, the basic principle of the method is briefly described. Then the possibilities of the method utilization for measurements of the object rotation, translation and vibrations are mentioned.
This paper extends the utilization possibilities of the joint transform correlator. The principle of the correlator can be used for determination of relative translation of two mutually displaced speckle patterns. An optical processor based on this architecture is designed. Such processor could be a part of an optical system for a noncontact measurement of object translations, rotations or deformations using the speckle decorrelation method. The paper presents computer simulation of the optical processor. In addition to basic theory of the processor the description of preparation of input data for the simulation analysis is mentioned. Both short description of the computing algorithm and some obtained results of the simulation are presented, too.
The paper analyzes measurement of stress by means of the method so-called speckle pattern decorrelation. This relatively new and easy realizable method for the non-contact measurement of the small deformation tensor components of an elementary area of the object surface using the statistical properties of speckle field was firstly studied by I. Yamaguchi and later by the authors of this paper, too. At first, the general description of the presented method is briefly referred and the fundamental equations are derived both for the case of optically free space and image field. Then some possible experimental arrangements for the measurement of the deformation component (specific elongation) on an investigated object rough surface are designed and analyzed from the point of view sensitivity and range of measurement. Finally, some achieved experimental results are also noticed.
This paper proposes another application for the joint transform correlator. The principle of the correlator could be used for determination of a relative translation of two speckle patterns. An optical processor based on this architecture is designed. Such processor could be a part of an optical system for a noncontact measurement of object translations, rotations or normal vibrations. This paper is devoted to operation simulation of the optical processor. Firstly, the theoretical description of the processor is made. Then follows a depiction of the preparation of input data for the simulation analysis. The detailed results of the simulation can be found in the last part ofthe paper
The paper deals with the theory of measurement of an object in-plane velocity (object as a rigid body) by means of the method availing the statistical properties of the speckle field (speckle pattern). At first, the general theory of determination of the small deformation tensor of an elementary area of an object surface using the electronic speckle correlation in the optically free space and in the image field is briefly mentioned. Furthermore, the philosophy of measurement and interpretation of measurement is presented and the analysis of sensitivity and accuracy is also shortly done.
This paper builds on the general theory of determination of the small deformation tensor by means of the method availing the statistical properties of speckle pattern propagating through free-space and image-field. It concentrates on vibrations determination in the direction of the normal to the object surface plane. In the first part of this paper the basic theoretical equations are mentioned, next some experimental configurations are designed for the measurement of the normal vibrations of an investigated object with a rough surface, finally the analysis of sensitivity and accuracy is done and some experimental results are also presented.