定义：提供干净光纤端面的仪器。

光纤光学中，通常需要用到具有干净整齐端面的光纤。通常采用切割得到，即控制性损坏。用于这一目的的仪器称为光纤切割刀。 

简单的切割刀片 
最简单的切割方法是只采用一个钻石刀片，放入笔形刻刀中，用其在光纤上沿着与光纤轴垂直的方向上刻一个非常小的刻痕。（注意不能用太大力刻光纤，否则不能得到很好的结果。）然后拿住光纤的一段，用手指将另一端去除，于是就完成了切割过程。也可以将光纤拉断。这种技术需要一些练习，得到的结果重复性也比较差。 
简单便宜的机械切割刀可以作为光纤端接套件的一部分。它们得到的结果比高质量精准切割刀重复性稍差。至少，它需要多次练习，通常情况下这种装置只能切割标准二氧化硅光纤。 

精准光纤切割刀 
采用更多控制条件的切割技术能够得到更高重复性的结果。因此，存在特殊的设备，称为机械式高精度光纤切割刀，工作原理如下： 

• 光纤放入切割刀中（剥离涂层后）固定，通常是一个V型槽和两个夹子。 
• 转动手柄提供一个拉力，其大小是可以调节的（例如，采用螺丝刀）。该应力不足以折断光纤。 
• 再转动第二个手柄，将钻石刀片缓慢接近光纤，产生刻痕。可以施加电磁力或者压力使刀片摆动。 
• 最后，提高拉力使光纤折断。 

采用这种切割刀，使用刀片时的拉力足够大使光纤折断。 
还有一些机械式半自动光纤切割刀，可以得到角度切割（见图1），即光纤端面与光纤轴之间有一定的非90°夹角。为了得到这一结果，光纤在切割之前是扭转的。扭转越强，得到的切割角度越大，它们之间的关系还与拉力有关，且得到的切割角度可能重复性较差。 

图1：当光从角度切割后的光纤中出来后可能会发生转向。图中也给出了反射光的方向，它不会再返回到光纤纤芯中。 
一些高精度光纤切割刀是熔接机的一部分，因为高精度切割是熔接的前提。

Definition: instruments for preparing fiber ends with clean optical surfaces

In fiber optics, it is often necessary to prepare clean surfaces for optical fibers. This is often done by cleaving, i.e., by controlled breaking. Instruments used for that purpose are called fiber cleavers.

For general aspects of cleaving, such as basic principles, problematic cases and the inspection of cleaving results, see the article on fiber cleavers.

Simple Cleaving Blades

The simplest cleaving method uses only a diamond blade, incorporated into a pen-shaped scribe, with which one manually makes a tiny scratch on the fiber, in a direction perpendicular to the fiber axis. (Note that too strong scratching can spoil the results.) One then holds the fiber on one end and gives the other part a kick with a finger, so that the cleave occurs. Alternatively, one may pull the fiber. Such techniques require some practicing, and the results are somewhat variable.

Simple and inexpensive mechanical cleavers can be part of fiber termination kits. They produce less consistent results than high-quality precision cleavers, as described below. At least, their use requires more practicing, and normally such devices are applicable only to standard silica fibers.

Precision Fiber Cleavers

Cleaving techniques with more controlled conditions allow for more consistent results. For that purpose, there are special apparatuses, called mechanical precision fiber cleavers, which work as follows:

• The fiber is inserted into the cleaver (after stripping its coating) and fixed, typically with a V groove and two clamps.
• By turning a handle, one then applies a tension, the magnitude of which can often be adjusted (e.g. with a screwdriver). That tension alone is not sufficient to break the fiber.
• With a second handle, one now carefully lets a diamond blade approach the fiber, causing the required scratch. The blade may be made vibrating with a small electromagnet or piezo.
• Finally, the tension is increased so that the fiber breaks.

With some cleavers, the tension during application of the blade is already high enough for the fiber to break.

There are versions of mechanical semi-automatic fiber cleavers which also allow for angle cleaving (see Figure 1), i.e., for preparing fiber ends with some angle against the fiber axis. For that purpose, the fiber is somewhat twisted before it is cleaved. Tentatively, stronger twisting leads to larger cleave angles, but that relation also depends on the tension, and there can be a substantial variation of cleave angles from try to try.

Figure 1: When light comes out of a fiber with angled cleave, it will be somewhat deflected. The direction for reflected light is also shown; it will not go back to the fiber core.

Some precision fiber cleavers are part of fusion splicing apparatuses, as precision cleaving is a prerequisite for successful splicing.