1492317386

(2)

r

i

L

L

f

Where do is the expected diameter of the object‘s section; L - distance from the matted glass to the sphere; f - focal distance of the lens; p - linear augmentation.

If the size of matted glass © will be smaller than optimal in accordance with expression (2), then a shadow will add up to the object s rims, that is the image's rim will be somewhat shifted from the centre; as a result the shadow image will be bigger than in reality. If © is bigger than the optimal then the shadow image will be somewhat smaller than in reality. Its size (diameter) d₂ will be connected with d₀ by the expression as follows [3]:

( ^2L )]

(3)

Considering the above mentioned reservation, the optical shadow implant images formation system was built whose scheme is provided on figurę 3. The registration of shadow images of implants was done with the aid of a CCD camera.

2.2. Optical speckle-images formation system

The building of fields of displacement of the implant s surface with the ODSC method employed a typical optical system of speckle images formation, as described in [4], An average size of speckle S, determined in accordance with the known formula

S = 1,22 — D

(4)

where A, is a wavelength of the source of radiation illuminating the study object, z -distance from the lens to the CCD camera which registers the speckle-image, is a major parameter to take into account when calculating the optical scheme for speckle formation.

In order to register a speckle-image by the CCD camera without distortions one must ensure the observance of the Nyąuist criterion by which the ratio between the step between pixels p_x and p_y of the CCD camera rectangular matrix sensor, and the average speckle size looks as follows [4]:

max | p _x, p _y | < 0.41 S

(5)

11