SU591239A1 - Ultrasonic collimator - Google Patents

Description

one

: The invention relates to ultrasound technology and can be used in devices that require the production of flat fields in the near field.

Ultrasonic collimators (lenses, reflectors) are known, the shape of the surfaces of which is determined from the conditions for obtaining a flat field, and the contour of the collimators is limited by the circumference l.

The closest in technical essence to the proposed is a collimator device containing an ultrasonic lens. 2

The purpose of the invention is to eliminate distortions of a flat floor edge. This is achieved by the fact that the device is equipped with a screen attached to the lens with an edge cut along its perimeter.

FIG. 1 shows a schematic collimator device; FIG. 2 - plane HOU of a rectangular coordinate system combined with the aperture plane.

The device contains an ultrasonic pczvzu 1 and screen 2.

The field in the near field of the in-phase excited aperture is described by the equation

F,

(one)

where Fr is the value of the function at the point of observation p-;

& o- plane, closely adjacent to the aperture;

3 - the surface bounding a certain region Y, where the scalar function H is given;

h = external normal to the surface Sj

..R is the distance from the element S. to the observation point P;

21G

- wave number.

Compatible with the plane of the aperture, the XPy plane of the rectangular coordinate system, directing the JI axis to the inside of the area. The origin of coordinates is compatible with the projection.

observation points p on the aperture plane (Fig. 2). Considering that

C S /. (R, .Z.). ()

Where

k1vrzhvte, defined chtsy amplitude unequality sex. the expression takes the form Since R "Z g, then; Зр" КН and dSгRclRdcA..Toj cr..) | S (IdTiadc Cr) consideration of the expression (4) it follows that the field (FFS) at any point above the aperture consists of ε. two components:, flat floor FPA. and the exciting field J in K - | gfs) 1 of the going aperture – rajev. The component flat pop does not depend on the position of the observation point if its projection lies within the aperture. The main field reaches a maximum when all its components coming from the edge of the apertures arrive in phase. This will be observed for a circular aperture if the projection of the observation point lies in the center of the circle.

)

F

B.rhox The total field is determined by the expression Fs1Go) FST),) e-5k “,))

50 With the edge cut up on lens perimeter.

Claims (2)

Sources of information taken into account in the examination: 4 lilitOt -Zo) (vZo) limits the phase unevenness of the field,. The extreme values of the amplifiers of the double knife are determined by the values. the phase cannot exceed ± 71/2., and by decreasing the distance Z the unevenness of the field must decrease. Thus, a circular aperture is most unsuitable for obtaining a uniform field. A screen with edges randomly cut by the size of a circular aperture, punctured in the path of waves coming from the edges of the aperture, phases the field of edge waves, which will lead to averaging of the disturbing field within the aperture. The use of a collimator device with a screen whose edges are cut by random law will increase the amount of space in which a quasi-flat field with small discontinuities is formed. Ultrasonic collimator device containing an ultrasonic lens, characterized in that, in order to eliminate distortions of a flat floor edge, it is equipped with a screen 551 attached to the lens. B. Kinber. E. Solving the inverse problem of geometric optics issue 3, 1955, p. 221-225, 2. Rosenberg, LD, The Use of Ultra-Sound, Academy of Sciences of the USSR, M, 1957, p. 67-71. g / / /