DE3405711A1 - Method and device for producing an end face on an optical glass fibre - Google Patents

Abstract

The invention relates to a method and a device for scribing and breaking glass fibre optical waveguides. An optical arrangement integrated into the device permits rapid observation of the fibre end face and a rapid, high-precision measurement of the angle of cut between the end face and fibre axis. The cause of a deterioration in end face quality and frequent deviations from the tolerable angle of cut is generally damage to the blade of the scribing tool. In the device according to the invention, for this reason the blade of the scribing tool is arranged displaceably, so that after a displacement of the blade perfect cuts are once again obtained.

Description

description

Method and apparatus for producing an end face on a optical glass fiber The invention relates to a method and a device for Production of an end face on an optical glass fiber according to the generic terms of Claims 1 and 4.

Optical systems with glass fiber optical waveguides are i> den in the next few years will be used to a rapidly increasing extent, both in the optical Communication as well as optical sensors, e.g. fiber optic gyros. In deratigen Systems is always a larger number of coupling points between the glass fibers available. For example, the light from a transmitter, e.g. a semiconductor laser, coupled into the fiber optics and from the Optical fiber on a photodetector be decoupled; different pieces of glass fiber have to be connected to each other e.g. by fusing (splicing). With such coupling points there is one very good quality of the end face of the glass fiber is an essential requirement for low optical coupling losses. In addition to the evenness of the end face, it is important also that the angle oc between the normal to the fiber end face and the fiber axis is as small as possible. For example, splice connections are made from single-wave glass fibers (Monomedic fibers can only be produced with loss of loss for angles α <1 °, i.e. the optical coupling losses are less than 0.1 dB.

The brittle consistency of the glass windows now allows the production of good end surfaces by scoring and breaking.

Because of its low cost and speed of execution, this is it Process especially for the mass production of transmitting and receiving components with fiber connector and very well suited for splicing in the field.

However, the method has a fundamental disadvantage: the fracture surface is not clearly specified by the scratch, the quality of the end face, e.g. Breakouts at the edge, and the size of the angle α is subject to fluctuations.

The cutting edge used for scoring, e.g. a knife edge, is also subject to this Made of Dianlallt or hard metal, a closure that leads to unusable end surfaces leads.

It is therefore advisable to check the end face produced.

From the publication by K.S. Gordon, E.G. Rawson and A.B. Nafarrate: "Fiber-break testing by interierfometry: a comparison of two breaking methods", Applied Optics, Vol.

16, No. 4, April 1977, pages 818-819, is a device tion known in which an optical fiber to be tested is secured in a holder in this way is that the end surface to be tested touches a glass plate, which is used as a reference surface in the case of an interferometer. So it is necessary to select the fiber to be tested to be tested in a separate test device. Such a process is uneconomical, especially in mass production. Furthermore, the aforementioned test device Disadvantage that the end surface to be checked must touch the reference surface, because as a result, undesired contamination of the end face is possible and / or even possible damage to the end face and / or the reference face.

The invention is therefore based on the object of providing a generic Method are to specify a generic device that is a cost-effective enable and reliable production of very good end faces on glass fibers, especially in industrial mass production.

This object is achieved according to the invention by the drawings in the kes Parts of claims 1 and 4 specified features. 7, wake-up arrangements can be found in the subclaims.

A first advantage of the invention is that it is in an industrial Mass production is possible after the scratching and breaking of the fiberglass the resulting Check the end face immediately. It is possible to check each end face for its usefulness to consider. Uneconomical rejects can be avoided.

A second advantage is that production is fully automated and testing of the end faces is possible.

This results in a considerable reduction in the cost of fiber-optic components accessible.

The invention is explained in more detail below with the aid of exemplary embodiments explained with reference to a schematic drawing. They show: FIG. 1 and FIG. 2 a first embodiment FIG. 3 shows a second embodiment.

According to FIG. 1 is first an optical glass fiber 10, also optical waveguide called, clamped in a holder shown hatched, which is a holder part 21 posses6, which is both movable in the longitudinal direction of the glass fiber 10 as well perpendicular to it. This is for example with the help of a ball-bearing cross table possible. An axial mechanical tensile stress is now first applied in the glass fiber 10 generated, e.g. by a motor (not shown) that acts on the movable mounting part 21 works. Then the glass fiber 10 is garitzt by a cutting edge 20, the consists of diamond or hard metal.

For this it is necessary that-the bracket has a counter bearing, on which the glass fiber 10 rests during the scratching. The existing tensile stress causes the glass fiber 10 to break at the point shown by dashed lines. It creates an end surface 12 (FIG. 2), which can be defective. For example @ annoying edge breakouts occur, which on a blunt and / or broken Cutting edge 20 are retractable. Farther can use the surface normal dor Elldilaclle 12 at a disturbing angle <x from the direction of the longitudinal axis the fiber 10 differ. To check the end face 12, the separated fiberglass part 11 removed, e.g. with the aid of the movable holder part 21 shifted perpendicular to the plane of the drawing. According to FIG. 2 is now in front of the end face 12 pivoted an interferometer, as a plane-parallel plate 30 contains with a partially reflective surface 31, which faces the end surface 12. the End face 12 is now also viewed through plane-parallel plate 30 With the aid of an overlay microscope operated with essentially monochrome light 33 will. The observer 34 sees an interference pattern from which the errors mentioned the end face can be derived. With this interference arrangement is at the plate 30 the surface 32, which runs parallel to the partially reflective surface 31, designed as a reference surface. It is not necessary to cover the surface 31 with a mirror layer the existing glass-air reflection is sufficient. The plate 30 is adjusted in the beam path that the surfaces 31, 32 are perpendicular to the Longitudinal axis of the glass fiber 10 that the end face 12 through the plate 30 is sharp is imaged and that at the same time the (reference) surface 32 after the reflection is also imaged in focus on the partially reflective surface 31. It that is, the light reflected at the end face 12 and the (reference) face 32 becomes brought to interference. A single-colored light creates an observable striped pattern, which represents a contour line image of the end face 12. If the distance between of the end face 12 and the face 31 um (# = light white length) so arises in the interference silver a Stripes. This allows the surface shape of the end face 12 the interference pattern will be revealed. The resolution limit αmin for the Angle 0: is given by the formula αmin = tan-1 ((# / 2) / d), where d denotes Means diameter of the glass fiber 10. For example, # = 0.5 µm and d = 125 µm the limit of resolution to #min = 0.10.

The embodiment according to FIG. 3 differs from the previous one only described by the fact that the observation of the resulting interference pattern takes place essentially perpendicular to the longitudinal axis of the glass fiber 10.

This is possible with a plate 30, the partially reflective Surface 31 is designed as a splitter mirror. It is possible to use the (reference) surface 32 11 mirror ulltl / or to protect against possible contamination The ii The interference image produced by the microscope is, for example, either visible to the eye evaluated and / or by a television camera with an attached electronic value unit. In the latter case, automatic image evaluation is possible. By the constant visual control of the end faces 12 produced will deteriorate their quality immediately determined. This troublesome deterioration is essentially caused due to wear and / or minimal chipping of the cutting edge 20 of the scoring tool. If the aforementioned deterioration is found, it is possible to remove the cutting edge 20 to move perpendicular to the longitudinal axis of the glass fiber 10 so that a sharp Area of the cutting edge is used. Alternatively, it is also possible to use the Cutting edge after a predeterminable number of scoring, e.g.

ten scratches by a specifiable amount, e.g. 1 µm to 5 µm move so that there is always a perfect cutting edge.

At the removed fiberglass part 11 (FIG. 1) is also created End face that is usable. This end face can also be checked optically, for example by aligning the described interference arrangement with this end face will.

The invention is not limited to the exemplary embodiments described limited, but also applicable to others. For example, it is possible in the case of the holder, make both holder parts movable.

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Claims (6)

Claims 1. A method for producing an end face on a optical glass fiber, in which the glass fiber is initially cracked and broken separated and the resulting end face is then checked, identified by the combination tolgen (lèr features: a) the glass fiber (10) is first in a Bracket tensioned and there using an axial tensile stress and through Scoring with a cutting edge (20) separated, b) after removing the separated The glass fiber part (11) is used in the case of the glass fiber (10) remaining in the holder resulting end surface (12) optically non-contact checked by the optical arrangement, which contains an optical interferometer, c) when a Wear of the cutting edge (20) becomes essentially perpendicular to the longitudinal axis of the Glass fiber (10) moved. 2. A method for producing an end face according to claim 1, characterized in characterized in that at the end face (12) at least their edge breakouts and / or whose direction of the surface normal is checked with respect to a specifiable direction. 3. A method of making an end face according to claim 1 or claim 2, characterized in that in addition to the separated fiberglass part (11) the resulting end face is checked optically without contact. 4. Apparatus for producing an end face on an optical glass fiber, in which the glass fiber is first separated by cracking and breaking and the resulting End face is then checked, characterized in that the holder is a movable Contains holding part (21), which at least in the direction of the longitudinal axis of the glass fiber is movable. 5. Apparatus according to claim 4, characterized in that for contactless optical inspection of the end face an intererometer is available, which is a plane-parallel Includes plate (30) which has a partially reflective surface (31). 6. Apparatus according to claim 4 or claim 5, characterized in that that an opto-electrical evaluation device is available for evaluating the from interference pattern generated by the interferometer.