这个原理与某些高档照相机能够自动对人脸进行聚焦非常相似。

The concept is similar to the way consumer cameras now can automatically make sure faces are in focus.

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红外照相机聚焦的是一根手指(或者相似大小的物体)破坏水平面、散射光线的点。

An infrared camera watches for spots where a finger (or similarly sized object) breaks the plane and scatters the light.

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试想像，我们的眼球犹如一部照相机，内有两个结构，用以聚焦光线，即角膜和晶体。

Think of the eye as a camera: it has two structures responsible for focusing light, the cornea and the lens.

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