the linear array probes have more than one crystal, in this explanation we refer to figure5, in
which the probe has seven crystals. The way an ultrasonic line is generated by an electronic
probe is not the same way it is done by mechanic ones, in electronic way an ultrasonic line
is generated by more than one crystal as seen in the figure 6, let us focus first in ultrasonic
line 3, crystal 3 generates an ultrasonic line the same way the mechanic probes do, the
crystals 2 and 4 generate one ultrasonic line each, these ends at the same point (Focus), at
this point also end the ultrasonic lines generated by crystals 1 and 5.According to the Huygens's principles, the net acoustic signal is the net sum of the signals that have arrived from
each source (in this paper each source is each crystal). At this point the contribution of every element is added in phase to produce a peak in the acoustic signal. At the focus, all the
ultrasonic lines generated by the crystals are added to generate a new ultrasonic line that is
the ultrasonic line which will go deep inside the human body as happened with the mechanic
probes. Taking the crystals as reference, let`s consider that the line generated by the crystal
3has00angle (y-axis), the line generated by crystal
Fig.4
Fig. 5
2 is at some angle degree–x0(at the left) and the line generated by crystal 4 is at the same
angle degree but with opposite sign+x0(at the right), and also it happen with line 1 –x0(at the
left), and line 5 +x0(at the right), of course the angle degree of lines 1 and 5 are bigger than
the angle degree of lines 2 and 4.The x components of the lines 1, 2, 4 and 5 are