cancelled but the y components, that is why the new ultrasonic line is on the y axis.
Fig. 6
Figure 7 shows five lines(+xA0line 5 and -xA0 line 1), (+xB0line 4and –x B0line 2),and (00
Line 3), xA and xB have some angle deviation, taking as example lines 1 and 5, the
line1have two components at the focus, L1F(y)and L1F(-x), one positive and another negative, the line L5 at the same point also have two components, L5F(y)and L5F(x),both positive,L1F(-x) and L5F(x) cancel each other because they have the same magnitude and opposite direction, this happens because both angles are equals but one positive and the other is negative, but L1F(y) and L5F(y) add each other in the y direction because both have
the same magnitude and direction, so their direction are the direction of the ultrasonic line
resulting from L1 and L5, then the same way linesL2 andL4 are added, line L3is added too
but this only has 00axiscomponent, this way by adding this five lines, it has been generated
a new line with the direction of the line 3, with the strength of the four (y) components L2F
(y),L4F(y), L1F(y), L5F(y)plus the total strength of L3 as shown in figure 7.
We have seen the way the ultrasound line is generated, but not how the lines arrive to
the focus with the appropriated direction and angle. Figure 8 shows that the path from crystal 1 and 5to the focus is larger than the path from crystal 2 and crystal 4 to the same focus,
and the shorter path is from the crystal 3, all the ultrasonic lines have equal speed of propagation, and all the ultrasonic lines generated by the crystals must arrived at the focus at the
same time, no matter how different the paths distances are among them, that is why the
crystals 1 and 5 must generate their ultrasonic lines first than the others (Pulse t1), later at
the right time, crystals 2 and 4 generate their ultrasonic lines (Pulse t2), and later also just
in time crystal 3 generates the center line (Pulse t3), and this way the first ultrasonic line of
the image area has been generated, the mechanic probes has a motor to move the crystals
from one place to another in order to generate the lines one by one at the right place, but
the electronic probes generate the lines one by one at the right place without moving any
crystal, the first ultrasonic line generated by adding L(1+2+3+4+5) is shown in figure 8, the
second line [ L(2+3+4+5+6) ] is generated by eliminating crystal