JP2610656B2 - Optical fiber observation device - Google Patents

Description

The present invention relates to an optical fiber observation device, and more particularly, to an optical fiber observation device.
The present invention relates to an optical fiber observation device that irradiates parallel light to the core axis of an optical fiber and observes the transmitted light to observe the state of the core axis of the optical fiber.

(Prior art)

Conventionally, as a device for observing the core axis of an optical fiber,
Utilizing the difference in the refractive index between the cladding and the core of the optical fiber, irradiating the optical fiber with light and observing the outer diameter of the core and the cladding from the transmitted light, Devices for searching for defects are known.

[Problems to be solved by the invention]

However, in the conventional optical fiber observation device, the amount of light applied to the optical fiber has not been automatically adjusted. Therefore, such adjustment of the irradiation light amount is left to the discretion of the operator using the optical fiber observation apparatus, and is performed manually. Therefore, the appropriate value of the irradiation light amount differs depending on each worker, and objective observation cannot be performed.

Further, in accordance with a change in the surrounding environment, for example, a change in temperature, etc., the irradiation light amount of the light source changes, or the imaging characteristics of the imaging device change, thereby changing the image data of the optical fiber and maintaining a uniform state. Was difficult to observe.
For example, if a light emitting diode (LED) is used as the irradiation light source, even when a constant current is applied,
It becomes bright and dark at high temperatures. for that reason,
Even if the irradiation light amount of the irradiation light source is adjusted to the optimum state at the beginning of the observation, if the ambient temperature fluctuates during the observation, the irradiation light amount of the light source deviates from an appropriate state, and accurate observation cannot be performed. In some cases, the core position and the like of the optical fiber cannot be correctly recognized.

An object of the present invention is to solve the above-mentioned problems and to provide an optical fiber observation device capable of always observing an optical fiber in an appropriate state.

[Means for solving the problem]

The present invention is directed to an optical fiber observation apparatus for observing an optical fiber having a core portion and a clad portion, wherein irradiation means for irradiating the optical fiber to be observed with parallel light, irradiation light directly irradiated from the irradiation means, and Imaging means for receiving the transmitted light transmitted through the optical fiber among the light from the irradiating means, and forming an observation image of the optical fiber and a background image formed by directly irradiating the irradiating light; and a background obtained from the imaging means. Control means for controlling the amount of irradiation of the irradiation means based on the brightness of the image, wherein the structure of the optical fiber is analyzed based on the images of the core and the clad included in the observation image.

[Action]

In the optical fiber observation apparatus of the present invention, the irradiating means irradiates the parallel light, and by irradiating the optical fiber with the parallel light, an observation image of the optical fiber is obtained in a shadow area of the optical fiber, and the irradiation is performed. A background image of the optical fiber is obtained in an area directly irradiated with light.

Here, the analysis of the structure of the optical fiber (for example, recognition of the core position, etc.) is performed based on the images of the core portion and the clad portion included in the observation image. In order to accurately and reliably perform the analysis. The present inventor has found that it is preferable to control the amount of irradiation of the irradiating means based on the brightness of the background image, particularly under the condition of parallel light irradiation.

Therefore, according to the invention of the present application, since the control unit for irradiating the optical fiber with the parallel light and controlling the irradiation light amount of the irradiation unit based on the brightness of the background image obtained by the imaging unit is provided, the core unit is provided. And the clad part are clearly identified,
It is possible to accurately and reliably recognize the core position and the like.

〔Example〕

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

Elements denoted by the same reference numerals have the same functions, and duplicate descriptions will be omitted.

FIG. 1 is a schematic block diagram of an optical fiber observation device according to the present invention.

As shown in this figure, the optical fiber observation device is provided with a light source 2 for generating light for irradiating the optical fiber 1, for example, a light emitting diode or the like. A lens 3 for converting the emitted light into a parallel light beam is provided on the front surface of the light emitting section of the light source 2. The microscope 4 that receives the irradiation light of the light source 2 (the direct irradiation light from the light source 2 and the light transmitted through the optical fiber) forms an observation image of the enlarged optical fiber of the optical fiber 1 and its background image. Two light emitting units are provided to face each other. Further, an imaging device 5 such as a CCD or a vidicon for converting the formed enlarged image into an electric signal is connected to the microscope 4. Further, the imaging device 5 processes an electric signal related to an observation image of the optical fiber replaced by the imaging device 5 to analyze the structure of the optical fiber,
A control circuit 6 is connected to control the current applied to the device and set the irradiation light amount to a desired value.

The control circuit 6 is provided with an operational amplifier 61 (hereinafter, referred to as an operational amplifier 61) that amplifies an analog signal related to an image of the optical fiber obtained from the imaging device 5. The operational amplifier 61 has an 8-bit analog / digital converter (hereinafter referred to as an A / D converter) 62 for converting the analog signal thus amplified into a digital signal of 256 gradations.
Is connected. The 8-bit output of the A / D converter 62 is connected to a central processing unit 66 (hereinafter, referred to as a CPU 66). Further, an 8-bit data buffer 64 is connected to the CPU 66. The 8-bit data buffer 64 stores the light source 2 transmitted from the CPU 66.
Is temporarily stored. Furthermore,
The output of the data buffer 64 is connected to an 8-bit digital / analog converter 68 (hereinafter referred to as a D / A converter 68). The D / A converter 68 is connected to the terminal of the light source 2. Furthermore, the control circuit 6 is provided with a data buffer 64 and a data decoder 63 for controlling the A / D converter 62. The data recorder 63 is connected to the CPU 66, and the data buffer 6 is transmitted to the CPU 66 in accordance with an instruction.
4 and the A / D converter 62 are controlled.

Next, an operation state when the optical fiber is observed by the optical fiber observation device will be described.

FIG. 2 shows an observation state with the microscope 4 in a state where the end faces of the two optical fibers are butted against each other and placed on an observation sample stand (not shown) of the optical fiber observation apparatus. In this figure, an observation image of the optical fiber 1 is scanned along a portion indicated by an XX line (hereinafter referred to as an image acquisition line) to acquire image information. In the observation image shown in FIG. 2, part A shows the core of the optical fiber, part B shows the outer diameter of the optical fiber,
Part C corresponds to the background part. Then, the imaging device 5 such as a CCD converts the light amount (brightness) of the image information at each scanning point into an analog electric signal, and transfers the analog electric signal to the operational amplifier 61 at a predetermined timing. The operational amplifier 61 amplifies the transferred analog signal and transfers it to the A / D converter 62, where the A / D
In the converter 62, the imaging device associates the maximum output value with 256, divides it into 256 (8-bit) gradations, and A / D converts the transferred analog electric signal. The timing of the A / D conversion and the output timing of the A / D converted image data are controlled by a data decoder 63 connected to the A / D converter 62. In this manner, the A / D converted image information is transferred to the CPU 66 as image data, processed according to a predetermined program, and recognition of the optical fiber core position and the like is performed.

Then, when this image data is recorded, it becomes as shown in FIG. In FIG. 3, A indicates a core portion, B indicates an outer diameter portion, and C indicates a background portion. As can be seen from FIG. 3 (a), it is difficult to recognize the contour of the core if the amount of light applied to the optical fiber 1 is not appropriate.
Even the core part recognition program built in U66 may not be able to recognize the core part.

Therefore, in the optical fiber observation apparatus of the present invention, based on the image data acquired and A / D converted, the optical fiber 1
Is automatically adjusted so that the core position and the like can be recognized by a core position recognition program.
As the method, first, a predetermined current value is set in advance, a current having the current value is applied to the light source 2, and a core position recognition program is executed by the above method to recognize the core position and the like. When the CPU 66 cannot recognize the core position or the like, the CPU 66 calculates an optimum irradiation light amount based on the acquired image information, and applies a current applied to the light source 2 so as to obtain the calculated optimum irradiation light amount. Control. Then, the image information of the optical fiber is taken in again, and the core position recognition program is executed to recognize the core position and the like. In this way, the current applied to the light source 2 is controlled so that the amount of light emitted from the light source 2 is optimal for recognition of the core position and the like. Then, with the irradiation light amount of the light source 2 being optimized,
Recognize the core position, etc. At this time, the operation of the control circuit 6 is such that data D1 corresponding to a predetermined current value
The data is transferred from the CPU 66 to the data buffer 64 and accumulated.
The data stored in the data buffer 64 is transferred to the D / A converter 68 in accordance with an instruction from the address decoder 63, converted into an analog value, and applied to the light source 2 as a current. In this state, the image information of the optical fiber described above is taken in, and the core position and the like are recognized according to the taken-in image information. Here, when the core position or the like cannot be recognized in an appropriate state, the CPU 66 determines that, calculates the optimum irradiation light amount based on the acquired image information, and obtains data corresponding to the optimum irradiation light amount. D2 is transferred to the data buffer 64, the data in the data buffer 64 is rewritten, the current value applied to the light source 2 is changed, the irradiation light amount is changed, the image information of the optical fiber is again taken in, the core position, etc. Recognize Here, when calculating the optimal irradiation light amount, the calculation is performed using the image data taken in and A / D converted.
A calculation method based on the ratio (contrast) between the light amount of the background portion C and the light amounts of the portions (A and B) corresponding to the optical fiber 1 shown in FIG. Further, when this contrast is obtained, the entire light amount of the background portion C is obtained by an integration process, and further, the entire light amount of the portions (A and B) transmitted through the optical fiber 1 is obtained by an integration process. Alternatively, the ratio of the integrated values may be obtained.

On the other hand, in recognition of the core position of the optical fiber 1 as described above, a light source 2 for irradiating light to the optical fiber 1 by manual operation is used.
When the brightness of the background portion C in the image information of the optical fiber 1 and the state of the core position recognition were examined while adjusting the current applied to the optical fiber 1, the following was found.

Recognition of the core position can be performed in the optimum state because the background brightness at the time of the maximum irradiation intensity of the light source 2 corresponds to 256,
That is when the irradiation intensity is divided into 256 gradations and the background brightness level is about 130. Also, it was found that the core position can be sufficiently recognized if the light intensity gradation level of the image information is 256. It is also known that when the brightness level of the background portion C is increased, the S / N ratio of the contour of the core portion is relatively improved, and the core boundary becomes clear.

Here, the initial value of the current applied to the light source was set to 5 mA, and the image information of the optical fiber was taken in along the image taking line (XX) shown in FIG. 2 to record the brightness level. However, the result shown in FIG. 3 (a) was obtained.
This current value corresponds to a brightness level of the background portion C of about 70. As can be seen from this figure, the core portion is not clearly recognized. Therefore, when the control circuit was operated to automatically adjust the irradiation light intensity of the light source 2, the current value applied to the light source 2 was set to 9 mA. In this state, the image information of the optical fiber was taken along the image taking line, and the brightness level was recorded.
The result shown in FIG. At this current value, the brightness level of the background portion C was about 130. Here, comparing FIG. 3 (a) and FIG. 3 (b), the contour of the core portion (the contour portion is shown as "A1" in FIG. 3 (b)) is shown in FIG. 3 (b).
It is clear that the state shown in FIG. 7 is several steps clearer, and the recognition accuracy is dramatically improved.

Further, in the above optical fiber observation apparatus, even when the amount of light emitted from the light source 2 and the imaging characteristics of the imaging device 5 change due to a change in the surrounding environment, the intensity of the emitted light from the light source 2 is always automatically adjusted to the optimum state during the optical fiber observation. Therefore, the optical fiber observation can always be performed in an optimal state.

The present invention is not limited to the above embodiment, and various modifications can be considered.

Specifically, in the above embodiment, an LED is used as an example of the irradiation light source.
However, the present invention is not limited to this, and any light source that can change the amount of irradiation by an applied current may be used.

Furthermore, in the above embodiment, when adjusting the irradiation light amount of the light source, the correction is performed based on the contrast ratio between the background portion and the optical fiber portion of the image information of the optical fiber observation, but is not limited thereto. For example, the adjustment may be made based solely on the brightness of the background portion.

〔effect〕

In the optical fiber observation device of the present invention, as described above, the irradiation light amount of the light source for irradiating the optical fiber is always adjusted to be optimal, so that uniform and objective observation can be performed. Thereby, by combining this optical fiber observation device and the fusion splicing device, fusion splicing of an optical fiber having stable quality becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an optical fiber observation device according to the present invention, FIG. 2 is a diagram showing an observation image of an optical fiber observed by the optical fiber observation device shown in FIG. 1, and FIG. FIG. 3 is a diagram in which a brightness level at an image collection line of the optical fiber observation image shown in FIG. 2 is recorded. 1 ... optical fiber, 2 ... light source, 3 ... lens, 4 ...
Microscope, 5: Imaging device, 6: Control circuit, 61: Operational amplifier, 62: 8-bit A / D converter, 63: Data decoder, 64: 8-bit data buffer, 66: CPU, 68
... 8-bit D / A converter, A ... core part, B ... outer diameter part, C ... background part, A1 ... outline part of core part.

Claims (2)

(57) [Claims] An optical fiber observation apparatus for observing an optical fiber having a core portion and a clad portion, comprising: an irradiating means for irradiating an optical fiber to be observed with parallel light; Imaging means for receiving transmitted light transmitted through the optical fiber among light and parallel light from the irradiating means, and forming a background image by directly irradiating an observation image of the optical fiber and the irradiating light, Control means for controlling the amount of light emitted from the irradiating means based on the brightness of the background image obtained by the imaging means; and the light based on the images of the core and the clad included in the observation image. An optical fiber observation device for analyzing the structure of a fiber. 2. The control means controls the irradiating means based on a ratio of a brightness of an observation image of the optical fiber obtained by the imaging means to a brightness of a background image of the optical fiber. 2. The optical fiber observation device according to 1.