JP2573473Y2 - Multi-core optical fiber test equipment - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-core optical fiber test apparatus for measuring the transmission loss of each optical fiber of a multi-core optical fiber cable.

[0002]

2. Description of the Related Art For example, as shown in FIG. 4, there is a flat multi-core optical fiber cable 20 in which a plurality of optical fibers 1 are molded with a flexible resin material 2 and arranged in parallel. It is necessary to test whether or not each of the optical fibers 1 is molded in a state in which light is normally transmitted at the time of manufacturing or before putting the multi-core optical fiber cable 20 to practical use.

FIG. 5 shows an outline of a conventional multi-core optical fiber cable test apparatus. 10A to 10D indicate light sources. This example shows a case where the optical fiber cable under test 20 is a four-core optical fiber cable. Light sources 10A to 10D
The coupling optical fiber 11 is led out of the multi-core optical fiber cable 20 for testing the coupling optical fiber 11.
To each of the optical fibers 1 to give light for testing.

Each of the light sources 10A to 10D supplies intermittent light at a frequency of, for example, about 270 Hz to the optical fiber under test and direct current light to the other optical fibers under test. In this way, the light sources 10A to 10D are always maintained in the lighting state, and converge to the stable light emitting state in a short time regardless of which light source is switched to the measuring state. Optical fiber cable 2
The optical sensor 30 is coupled to the other end of the zero. Optical sensor 3
0 is optically coupled in common to all of the four-core optical fibers, receives intermittent light including DC light, supplies the electric signal to the optical power measuring device 40, measures the optical energy of only the intermittent light, The transmission loss of each optical fiber 1 is measured.

FIG. 6 shows the internal structure of the optical power measuring device 40. Reference numeral 30 denotes an optical sensor. The light sensor 30 is provided with intermittent light including DC light, and outputs a current I proportional to the light energy. The current I output from the optical sensor 30 is a current-
The voltage signal is converted into a voltage signal by the voltage converter 41, and the DC signal is removed by the capacitor 42, and the intermittent signal from which the DC component is removed is input to the band-pass filter 43. To obtain a sine wave signal. This sine wave signal is double-wave rectified by an AC / DC conversion circuit 44, the double-wave rectified pulsating current is smoothed by a low-pass filter 45, and the smoothed output is input to, for example, an AD converter 46, and AD-converted. It is given to a numerical display or the like to display the optical power value of the intermittent light.

[0006]

In the conventional multi-core optical fiber test apparatus shown in FIGS. 5 and 6, the light source of the channel in the non-test state is lit by DC as described above.
During the test from the DC lighting state, the DC current I _DC is turned on and off as shown in FIG. Therefore, immediately after switching from the non-test state to the test state, the average current I
₀ becomes 1/2. For this reason, in each of the light sources 10A to 10D, the thermal balance is lost and the light power fluctuates.
Optical power stabilizes to a value corresponding to the intermittent current I _ON-OFF
It takes about several minutes to reach the thermal equilibrium state .
If a test is performed while the optical power is fluctuating, stable data cannot be obtained. Conventionally, each time a test channel is switched, a wait time of several minutes is required, and the test cannot be completed in a short time. There are drawbacks.

As one method of solving this drawback, all the light sources are always intermittently lit at different frequencies, the signal of each frequency is selected by a filter on the optical power measuring device side, and the level of the selected and extracted signal is measured. There has been proposed a method of measuring the optical power by using the method. However, in the case of such a configuration, there is a limitation in the allocation of the frequency for intermittent lighting.
Multi-channel is difficult. In other words, the LED that is the light source
This is because there is an upper limit on the frequency that can respond to intermittent lighting, and the number of channels that can be allocated within a limited band is also limited.

In the optical power measuring device, a filter must be prepared for each channel. Therefore, when the number of channels is increased, there is a disadvantage that the configuration becomes complicated. An object of the present invention is to propose a multi-core optical fiber test apparatus which does not require a waiting time when switching test channels and can easily achieve multi-channel (tens of channels).

[0009]

According to the present invention, all the channels in the non-test state are intermittently lit at one frequency different from the frequency of the channel under test. By this intermittent lighting, an average current equivalent to that of the intermittent lighting during the test can be given to the light source of the channel in the non-test state.

[0010] Therefore, according to the present invention, the optical power measuring device always needs to measure only the signal of the intermittent lighting frequency for the test, so that only one filter may be provided. Therefore, even if the number of channels is increased, the configuration can be simplified. In addition, all the light sources of the channels in the non-test state need only be intermittently lit at the same non-test frequency that is different from the test intermittent frequency. The number of channels can be easily set.

[0011]

1 and 2 show an embodiment of the present invention.
In this invention, switching means 12A to 12D for switching the intermittent lighting frequency are added to each of the light sources 10A to 10D. As a form of the switching means 12A to 12D, the light sources 10A to
There are two possible configurations, one in which an oscillator for generating an intermittent lighting frequency is built in all of the 10Ds, and the other in which the oscillator is shared externally.

When oscillators are incorporated in all of the light sources 10A to 10D, oscillation frequency switching means is added to each of the oscillators, and the oscillation frequency switching means is controlled to control the oscillators provided in the light sources 10A to 10D of each channel. The switching frequency of the oscillation frequency can be controlled. When the oscillator is provided externally, an oscillator for oscillating the intermittent lighting frequency for test and an oscillator for oscillating the intermittent lighting frequency for non-test are provided. In addition, each of the light sources 10A to 10D can be configured such that only a signal of a required frequency is taken in by a gate circuit or the like, and the light sources 10A to 10D are turned on and off by the signal. Therefore, when the oscillator is provided outside, the gate circuit constitutes the frequency switching means.

[0013] The two oscillators 13 and 14 to the outside of the light source 10A~10D in the embodiment of FIG. 1 is provided, the signal S of the signal S ₁ and the non-test for intermittent frequency of the test intermittent frequency between the two oscillators 13 14 ₂ and the two signals S
Gives ₁ and S ₂ in each of the light sources 10A to 10D, the light sources 10A
In ~10D shows a case where the one of the two signals S ₁ and S ₂ as capture selected by the frequency switching means 12A-12D.

The frequency switching means 12 A to 12 D are controlled by the controller 15, and one of the channels is output from the oscillator 13 at the test intermittent frequency signal S _1.
Select the other channel selecting signal S ₂ Intermittent frequency for non-test. Each frequency switching means signals S ₁ and S ₂ that are selected by 12A~12D intermittent circuit 16A~1
6D, and causes the light emitting elements 17A to 17D such as LEDs to emit light intermittently at the frequency of this signal. Light emitting element 17
A to 17D are optically coupled to the coupling optical fiber 11, and the coupling optical fiber 11 is connected to each optical fiber of the multi-core optical fiber cable 20 to be tested. Is provided with intermittent light.

At the other end of the multi-core optical fiber cable 20, an optical sensor 30 optically coupled to each optical fiber 1 (see FIG. 4) is provided, and is proportional to the power of light received by the optical sensor 30. Is converted to a current. The current signal output from the optical sensor 30 is input to the optical power measuring device 40.
The optical power measuring device 40 can be configured as shown in FIG. The current signal output from the optical sensor 30 is converted into a voltage signal by the current-voltage converter 41. The DC signal is removed from this voltage signal by the capacitor 42 and the bandpass filter 4
Obtaining a full-wave rectified pulsating current in the filters only test intermittent signals S ₁ at 3 AC / DC converter 44. This pulsating current is filtered by the low-pass filter 45 and converted into a stable DC signal.
The DC signal filtered by the low-pass filter 45 is input to an AD converter 46 as necessary, and is AD-converted and input to a numerical display or the like.

The frequency f _O of the test intermittent light is, for example, f _O =
The frequency f _{M of the} intermittent light for non-test can be selected to be 270 Hz, duty 50%, and the frequency f _M = 1000 Hz and duty 50%. Therefore, the bandpass filter 43 has 27
A bandpass characteristic for passing 0 Hz is provided. Signal S ₂ with interrupt frequency f _M for non-test by the band-pass characteristics of the band-pass filter 43 is removed.

When the transmission loss of one optical fiber is tested, the channel for selecting the signal S ₁ is shifted, and the transmission loss of each optical fiber 1 of the multi-core optical fiber cable 20 is sequentially tested one by one.

[0018]

As described above, according to the present invention, the light emitting element of the channel under test is also intermittently emitted with a signal of 50% duty different from the intermittent frequency for test, as shown in FIG. Even when switching from the non-test state to the test state, the average current I _O does not change if the duty of the signals S ₁ and S ₂ are both set to the same value, for example, 50%.
Therefore, even when the test channel is switched, the light emitting elements 17A to 17A to 1
The average value of the drive current supplied to 7D does not fluctuate.
Since the thermal equilibrium of the elements 17A to 17D is maintained , the power of the emitted light is maintained at a constant value.

As a result, the test can be performed immediately after the test channel is switched, so that it is not necessary to provide a waiting time, the test can be performed continuously, and the multi-core optical fiber cable can be tested in a short time. it can. The frequency used regardless of the number of channels from all the channels gave signals S ₂ of the same frequency in a non-test state, according to this invention need only two. Therefore, the number of channels is not limited, and multi-channeling can be easily achieved.

[0020] Because was configured to dispense the test frequency f _O in one, to the optical power meter 40 need only provide a single bandpass filter 43 regardless of the number of channels. Therefore, even if the number of channels is increased, the optical power measuring device 40
There is no inconvenience such as an increase in the configuration and scale of the device. In the above embodiment, the case where the frequency f _O of the signal S ₁ is set to 270 Hz and the frequency f _M of the signal S ₂ is set to 1000 Hz is not necessarily limited to this frequency. Further, if the relation of harmonics is avoided, f _M can be selected to be lower than f _O.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing an example of an optical power measuring device used in the multi-core optical fiber testing device of the present invention.

FIG. 3 is a waveform chart for explaining the operation of the present invention.

FIG. 4 is a cross-sectional view illustrating an example of a multi-core optical fiber cable.

FIG. 5 is a block diagram for explaining a conventional technique.

FIG. 6 is a block diagram similar to FIG. 5;

FIG. 7 is a waveform chart for explaining inconvenience of the conventional technique.

[Explanation of symbols]

 Reference Signs List 1 optical fiber 2 mold 10A to 10D light source 11 coupling optical fiber 12A to 12D frequency switching means 13, 14 oscillator 15 controller 16A to 16D intermittent circuit 17A to 17D light emitting element 20 multi-core optical fiber cable 30 optical sensor 40 optical power measuring instrument

Claims (1)

(57) [Scope of request for utility model registration] A light is incident on each optical fiber of a multi-core optical fiber cable, light transmitted through each optical fiber is received by a light receiver, and energy of the light transmitted through each optical fiber is measured by an optical power measuring device. In a multi-core optical fiber test apparatus that measures and measures the optical transmission loss in each optical fiber, a state in which a light source that gives light to each optical fiber is intermittently lit at a test frequency, and a non- A switching means for switching between intermittent lighting at a test frequency is provided so that only one optical fiber of a multi-core optical fiber cable is provided with light intermittently lighting at a test frequency, and the other optical fibers have a non-test frequency. A multi-core optical fiber test apparatus configured to provide light that is intermittently lit at a time and to equalize the average value of the drive current supplied to the light source in both the state during the test and the state during the non-test.