Abstract: A device for displaying the core (C) of an optical fiber (F) in two directions that are transverse to the fiber (F) includes two light sources illuminating the fiber. Each source emits a beam of light. The beams have different directions D.sub.1 and D.sub.2. The directions lie in a plane that is orthogonal to the longitudinal axis (X) of the fiber (F). An objective lens (L.sub.3, L.sub.4), reception and display components (2, 3) are employed and receive and display images of the fiber (F) produced by the beams. The objective lens is focused in a plane (P) that intercepts the beams from the fiber (F) inside the fiber (F). The angle (.alpha..sub.1, .alpha..sub.2) between either of the directions (D.sub.1, D.sub.2) and the focal axis (Y) of the objective lens (L.sub.3, L.sub.4) is such that the objective lens (L.sub.3, L.sub.4) directly receives the two beams from the fiber (F) with sufficient light intensity to enable the display component to operate.

Abstract: A device for use in on-site conditions to obtain a section plane which reproducibly makes an angle of 5.degree., for example, relative to the axis of an optical fiber. The device includes a clamp for holding the fiber at a first point, a rotary clamp for holding the fiber at a second point and for twisting it about the axis of the fiber. The device further includes two jaws for holding the fiber at a third point after it has been twisted by means of the rotary clamp. A convex anvil subjects the fiber to tension after it has been twisted. A diamond cutter is employed for cleaving the fiber. The invention is applicable to providing an optical fiber cutting tool suitable for cutting the fiber obliquely on the worksite.