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Figurę 3. Scheme of incoherent optical system for forming of implant shadow images with CCD camera: 1 - light source, 2 - collimator, 3 - focused screen, 4 - cylinder or cone (frustum) crosscut, 5 - stop, 6 - lens, 7 - CCD camera.

The procedurę of construction of the displacement fields by means of digital speckle-correlation (DSC) is well-known and is described in a number of publications [4-6]. At the same time, the ODSC method we propose [2,7] differs from other similar ones by its ability to augment the ratio of intensity of the correlation peak to the level of surrounding noise, as well as to narrow the width of the peak by using non-linear spatial filters with the median and adaptive median thresholds. In order to increase the effectiveness of the method we also proposed a new way of non-linear tran sfor mation of the common energy spectrum with the use of the circular local median threshold which takes account of the circular structure of the spectral density of the power of the speckle-image [2, 7]. The results of Computer modeling and experimental studies demonstrated that the use of the circular median threshold allows to increase the ratio ‘correlation peak/noise' by a degree as compared with traditional DSC methods [2,7]. The scheme of optical system of formation of speckle-image on the implant" s surface is given on Figurę 4.

3. Experimental studies

The speckle-images, formed with the aid of built systems, were processed with the aim to construct the displacement fields and deformations, as well as the shadow images of the implant" s surface. During the studies we used a pointed mechanical loading on the implant leading to its bending. We registered a series of shadow images and speckle-images by which we determined the implant s displacement and its bending angle. Figurę 5a shows the implant's image, figurę 5b - its speckle-image, figurę 5c -image of the displacement field from the interim position of its bending, which corresponds to the displacement if the uppermost part of the implant"s tip by 4.9 mm and the bending angle of the implant relative to the vertical axis, equal to 36,5°, to the next interim position which correspond to displacement of the same part of the tip by 5.1 mm and the implant's bending angle relative to the vertical axis equal to 37,6°. Arrow “1 " designates the area of maximal local bulge of the implant's segment. In this area we see a sharp change of direction of displacement fields, when the lower and upper parts of the implant have predominant directions of displacement vectors of speckle-images fragments, which differ among each other sharply. There is a zonę between them where predominant displacements in a particular direction are missing. Besides, in this zonę they are considerably smaller than displacements in the lower and upper parts of the implant. Therefore, the place of transition from on direction to

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