JPS60253837A - Optical fiber analyzer - Google Patents

Abstract

PURPOSE:To clear each step, by a method wherein the start points of the steps due to connection loss in the waveform displayed on CRT are set as indication points and a places coming near to a terminal side by a length more than the pulse width or more of measuring light from the indication points are set as fixed points while the spaces between the fixed points and the next indication points are displayed in a linearized state. CONSTITUTION:In an optical fiber analyzer wherein a measuring light is incident on an optical fiber 3 from a light source 1 through a directional coupler 2 and the reflected wave thereof is detected by a detector 4 to be displayed on CRT5, start points C21, C22 of the steps caused by the pulse width of measuring light on the displayed wave form C2 of the reflected wave are set as indication points and points C22, C24 coming near to the terminal side by a length two times or more the pulse width from the indication points are set as fixed points. For example, the fixed point C22 and the next indication point C23 are connected by a straight line and the intersecting point of the extended line of said straight line and the perpendicular line from the indication point C21 is set as a point C25 and the attenuation quantity of the step is known from the length between the point C21 and the point C25.

Description

Detailed Description of the Invention (?L) Technical Field of the Invention The present invention provides an optical fiber analyzer for measuring the attenuation characteristics of an optical fiber or fibers including a plurality of connection points. By clearly displaying the resulting step difference, it is possible to simultaneously calculate the unit length loss of the optical fiber, the splice loss of the entire section, etc.

(b) Conventional technology and problems First, a configuration diagram of a conventional device is shown in FIG.

In FIG. 1, 1 is a light source, 2 is a directional coupler, 3 is an optical fiber to be measured, 4 is a detector, and 5 is a CRT.

A light source 1 shown in FIG. 1 inputs measurement light into an optical fiber 3 via a directional coupler 2. The reflected wave of the measurement light from the optical fiber 3 enters the detector 4 via the directional coupler 2 6
The reflected wave converted into an electric signal by the ei output device 4 is sent to the CRT 5.
will be displayed.

Next, FIG. 2 shows an example of the reflected waveform displayed on the CRT 5 of FIG. 1.

The left side of the waveform CI in FIG. 2 shows the state of an example of the input end 31 of the optical fiber 3, and as it moves to the right side, the light beam decreases.

The waveform CI slopes downward to the right, indicating that the reflected waveform attenuates as it goes to the right.

There is a step at point C and point CI2 of waveform CI, but
These steps are caused by connection loss of the optical fiber 3. It can be seen from the waveform in FIG. 2 that the optical fiber 3 is a combination of three optical fibers.

The level difference occurring at point C11% and point CI2 is not a vertical waveform vertically, but a waveform shifted to the right.

This is because the analyzer has a limited bandwidth.
Usually, the lateral length of the step is less than twice the pulse width of the measurement light incident on the optical fiber 3.

In an ideal state, the width is shifted by one pulse of the measurement light.

In the waveform shown in FIG. 2, the splice loss due to each level difference is unclear, and it is difficult to measure the loss of each unit length of an optical fiber including a plurality of splice points, the splice loss of the entire section, etc.

(c) Purpose of the Invention This invention uses the beginning of a step that appears on a waveform as a designated point, and also defines a point that is a certain length from each designated point toward the end of the optical fiber as a fixed point, and By making straight lines between specified points, each level difference in an optical fiber having a plurality of connection points can be clarified and the optical fiber characteristics can be measured.

(d) Embodiments of the Invention First, the method of determining designated points and fixed points according to the present invention will be explained with reference to FIG.

Waveform C2 in Figure 3 is similar to waveform C+ in Figure 2,
This is a waveform when measurement light is incident on the optical fiber 3 in FIG. 7S1 from the input end 31 side.

FIG. 3 shows an example of a waveform when three optical fibers are connected, and points C21 and C23 are the beginning of a step. In this invention, the start of this step +6 (')
Point C2+ 1 Point C23 is designated as the designated point.

Point C21% The portion following point C23 is shifted in the horizontal direction. This is because, as explained in the case of FIG. 2, the analyzer has a limited bandwidth.

In an ideal state, the specified point 021 is as long as the pulse width of the n1 constant light, usually more than twice the pulse width of the measurement light.
A point C2° closer to the terminal side of the optical fiber 3 from point C23,
At point C24, the waveform is not affected by the level difference.

Note that a pulse with a pulse width of about 0.1 to 2 μs is often used as the measurement light.

In this invention, point C22 and point C24 are fixed points.

For example, if a straight line connects fixed point C22 and the next designated point C2G, and the intersection of the extension of this straight line and the perpendicular from designated point C21 is shifted from point C16, then the length of point C2+ and point C25 or point C2+ It shows the amount of attenuation depending on the step number of the part.

In this way, in this invention, in the waveform displayed on the CRT δ, the beginning of each step is set as a designated point, and the distance from each designated point to the end of the destination fiber is determined by a distance equal to or longer than the pulse width of the measurement light. However, by setting each point as a fixed point and creating a straight line between each fixed point and the next designated point, the amount of attenuation at each level difference is clarified.

(o) According to this invention, when reflected light from an optical fiber including multiple connection points is displayed on a CRT, the amount of attenuation due to connection loss at each connection point becomes clear. It is possible to simultaneously calculate the unit length loss of an optical fiber, the splice loss of the entire length, etc.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional device, FIG. 2 is an example of a reflected waveform displayed on the CRT 5 shown in FIG. 1, and FIG. 3 is an explanatory diagram of how to determine designated points and fixed points according to the present invention. 1. Light source, 2... Directional coupler, 3...
...Optical fiber, 4...Detector, 5...-
CRT, 31...Incidence end, 32...Terminal. Patent applicant: Tohoku Electric Power Co., Ltd. Ando Electric Co., Ltd. Agent: Kinji Omata, patent attorney

Claims (1)

[Claims] 1. Injecting measurement light into an optical fiber including a plurality of connection points, detecting the warpage (waves) of the measurement light by the optical fiber with a detector, and displaying the output of the detector on a CRT. In the optical fiber analyzer, among the waveforms displayed on the CRT, the beginning of the step caused by connection loss at the plurality of connection points is designated as a designated point, and from each designated point the length is equal to or longer than the pulse width of the measurement light. An optical fiber analyzer characterized in that the points near the terminal side of the optical fiber are set as fixed points, and the points between the fixed point and the next specified point are each displayed in a straight line.