To do all this, though, you need a device called a transducer.

但完该过程，你不能缺少一台叫做‘压电式换能器'的设备。

Then, the transducer uses the reflected waves to create an image.

然后， 换能器使用反射波创建图像。

To make a transducer by painstakingly micro-machining a brittle block of ceramic material can take many hours of work, though.

压电式换能器需要用到陶瓷材料，而精密地加工一块精细的陶瓷材料就要耗费几个小时的工作时间。

Transducers are made from arrays of tiny piezoelectric structures that convert electrical signals into ultrasound waves by vibrating at an appropriate frequency.

压电式换能器是由具有‘压电'效应的一系列敏感元件机构组。敏感元件机构通过‘定频'震荡将电信号转换波。

The GE process for making a transducer begins by spreading onto the print table a thin layer of ceramic slurry containing a light-sensitive polymer.

GE对加工换能器的方法是首先在印刷台上撒上薄薄的一层陶瓷粘土，其中混入一种光敏聚合体。

However GE, a large American conglomerate, is now proposing to make ultrasound transducers by " additive" manufacturing—or three-dimensional printing, as it is also known.

而GE作为美国的一个庞大的企业集团正考虑采用‘对比添加式'的加工流程（或者又称大家所熟悉的‘3D印刷'）来加工波压电式换能器。

Doctors can use an ultrasound transducer to make ultrasound waves that travel through your body, and reflect off different squishy bits, like organs, or a fetus.

医生可以使用波换能器产生穿过您身体的波，并反射不同的软质部分， 如器官或胎儿。

The waves are then reflected back from areas where there is a change in density and on their return the transducer works in reverse, producing a signal which the scanner can process into a digital image.

波会从密度发生变化的介质反射回来，这时压电式换能器会反向操作产生信号，再经过扫描器的处理，最后进行数字像。

So for example, we can make them all come together to a point, and they can we can make transducers from the bottom and from the top come to two different points that are half a wavelength apart.

举个例子，我们可以将它们汇聚到一个点上，我们可以让换能器分别从底部和顶部到达两个相距半个波长的点。