JPH0682214A - Optical fiber centering position detector - Google Patents

Abstract

PURPOSE:To always detect a positional deviation of an optical fiber by checking the reflected light returning from both end faces of the optical fiber with a beam splitter to measure the intensity of the reflected light. CONSTITUTION:A laser light 2 to be outputted from a laser oscillator 1 passes through a beam splitter 3 and is condensed onto an incident end face of an optical fiber 5 with a condenser lens 4. The laser light 2 condensed with a lens 4 can be admitted into the fiber 5 with the minimum loss when it coincides with the inner diameter of a core of the fiber 5 Thereafter, the laser light 2 transmitted through the optical fiber also causes an end face reflection by about 4% at an output end to be emitted from the fiber 5. In this manner, the laser light equivalent to about 4% as reflected at an incident end of the fiber 5 and the laser light equivalent to about 4% as given when the laser light 2 transmitted reflects at an emission end both make a return light 8 to be admitted into a photodetector 6, is reflected with the beam splitter 3 and the intensity of the laser light is shown on a display device 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam machine for guiding a laser beam through an optical fiber to cut a metal plate or the like, and to centering of an optical fiber such as a medical laser knife using the optical fiber.

[0002]

2. Description of the Related Art Conventionally, the adjustment of the centering position of an optical fiber in a laser processing apparatus in which a laser oscillator and an optical fiber are combined is performed by measuring the laser light output on the laser oscillator 1 side as shown in FIG. The beam splitter 3 splits the laser light 2 and includes a detector 6 and a display 7 for measuring the laser power, and a detector 31 and a display 32 for measuring the emitted laser power at the output end of the optical fiber. The position of the incident end of the optical fiber 5 is adjusted by moving it in the X, Y and optical axis directions so that the output power at the output end of the fiber is maximized and the transmittance of the optical fiber is maximized.

[0003]

In this conventional optical fiber adjusting method, both ends of the optical fiber must be located at positions close to each other, and it is difficult to adjust the optical fiber after it has been laid in advance. In addition, there is a problem that the measurement cannot be performed during the processing work performed by attaching a processing condenser lens to the exit end of the optical fiber.

[0004]

An optical fiber centering position detecting device of the present invention comprises a beam splitter for detecting reflected light returning from both end faces of an optical fiber and an optical power meter for measuring the intensity of the reflected light. I have it.

[0005]

The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the present invention. The laser beam 2 output from the laser oscillator 1 passes through the beam splitter 3 and is condensed by the condenser lens 4 on the incident end face of the optical fiber 5. In the structure of the optical fiber, as shown in FIG. 2, the central core 21 has a larger refractive index than the peripheral cladding layer 22, and the reflectance at the end face is about 4% at the core portion. Is. Due to the nature of the optical fiber 5, the light incident on other than the core portion of the central portion is not completely led out and is scattered around the optical fiber to cause a loss. Therefore, when the laser light 2 condensed by the condenser lens 4 matches within the core diameter of the optical fiber, it can be incident on the optical fiber with a minimum loss. After that, the laser light transmitted through the optical fiber also undergoes end face reflection of about 4% at the output end and is emitted from the optical fiber.

As described above, both about 4% of the laser light reflected at the incident end of the optical fiber and about 4% of the laser light incident on the optical fiber and transmitted at the emitting end are reflected in FIG. Return light 8 of, which is reflected by the beam splitter 3,
It is incident on the photodetector 6. This laser light intensity is displayed on the display 7.

[0007]

As described above, according to the present invention, the reflected light at both the entrance and exit ends of the optical fiber is measured. Particularly, the reflected light intensity at the exit end is the laser light intensity passing through the optical fiber. When is the maximum, since the maximum point is used,
It becomes possible to constantly detect the positional deviation of the optical fiber.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a sectional view of an optical fiber.

FIG. 3 is a configuration diagram showing a conventional measuring method.

[Explanation of symbols]

 1 Laser Oscillator 2 Laser Light 3 Beam Splitter 4 Condensing Lens 5 Optical Fiber 6 Photodetector 7 Display 8 Return Light 21 Core 22 Cladding Layer 31 Photodetector 32 Display

Claims (1)

[Claims] 1. A laser oscillator, a condenser lens arranged in front of the laser oscillator for condensing laser light to an incident end of an optical fiber to be measured, and a photodetector for converting laser light intensity into an electric signal. A beam splitter which is disposed between the laser oscillator and the optical fiber under test and which displays the output of the photodetector, and which reflects the reflected light from the end face of the optical fiber under test to the photodetector. An optical fiber centering position measuring device comprising: