JPH06148029A - Measuring method for gradient angle of optical fiber and light connector - Google Patents

Abstract

PURPOSE:To highly accurately measure a gradient angle of an optical fiber with respect to a light connector end face by calculating a center position of an optical fiber end face obtained per distance of an image pickup system and a change in distance to the connector front end face of the image pickup system to perform arithmetic operation based on these values. CONSTITUTION:A focus of a CCD camera 23 is aligned with a core end face of an optical fiber 41 exposed at a front end face of a light connector 101, and while the camera 23 is gradually brought close to the connector 101 front end face with the focused position as a reference, an image of emitted light from the core end face is picked. A plurality of the core end face images which have been picked are stored in an image processor 61. The processor 61 uses the image pickup data to detect edges of the core end face images to obtain a center position coordinate. A change in distance DELTAz of the camera 23 to the connector 101 front end face and a change DELTAx in the center position of the core end face are calculated from the obtained center position coordinate, and tanthetaa=DELTAx/DELTAz is used to obtain a gradient angle thetaa of a core axis of the fiber 41 with respect to a normal line of the connector 101 front end face.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for measuring the tilt angle of an optical fiber with respect to an optical connector.

[0002]

2. Description of the Related Art Conventionally, as a technique for measuring the core eccentricity of an optical connector, "High-precision dimension measurement technique for multicore connector" of B-343 of the National Conference of the Institute of Electronics, Information and Communication Engineers in 1988 is known. . FIG. 11 is a perspective view schematically showing this. The optical connector 101 is set on a stage (a movable stage in the X and Y directions) (not shown), and is illuminated by the illumination light source 102 from the rear end face. Optical connector 1
An image pickup device 104 such as a CCD is arranged on the front end face side of 01 with the objective lens 103 interposed therebetween.
An image of the front end face of the image is formed on the image pickup device 104.

Here, the optical connector 101 is provided with two guide pin holes 105 on both sides, and a large number of fiber holes 106 are formed between them. Therefore, the illumination light from the illumination light source 102 is guided by the guide pin hole 105.
Then, it passes through the fiber hole 106 and becomes transmitted illumination light, which is incident on the imaging device 104. The image processing device 107 is provided with image data of transmitted illumination light from the front end face of the optical connector 101.

Therefore, since the image processing apparatus 107 can obtain the contours of the edges of the front end faces of the guide pin hole 105 and the fiber hole 106, the center positions of the guide pin hole 105 and the fiber hole 106 can be obtained from the results. Therefore, by comparing this measured center position with the designed center position, the so-called eccentricity amount and eccentric direction can be obtained,
Enables product evaluation. The CRT 108 visually displays the imaging data and the measurement result.

[0005]

However, due to the existence of the clearance between the fiber hole 106 and the optical fiber, the optical fiber inserted therein may be inclined. Therefore, in the above-mentioned prior art, the fiber hole 1
Although the eccentricity of 06 can be evaluated, when an optical fiber is inserted and actually used as an optical connector, there are cases where it is not possible to perform suitable optical coupling.

The present invention provides an optical fiber tilt angle measuring method capable of highly accurately measuring the tilt angle of the optical fiber with respect to the front end face of the optical connector in an actual use state in which the optical fiber is inserted into the optical connector, The object of the present invention is to accurately perform product evaluation of an optical connector in an actual use state and realize suitable optical coupling.

[0007]

According to the present invention, an image pickup system is focused on one end face of an optical fiber exposed at the front end face of an optical connector, and the image pickup system is moved from the front end face of the optical connector from this focused position. The light emitted from the above-mentioned one end face of the optical fiber is imaged while keeping away from it, and from the plurality of end face images of the optical fiber imaged by the image pickup system located at different distances from the front end face of the optical connector, Obtain the center position of the fiber end face, and from the change in the distance to the front end face of the optical connector of the imaging system and the change in the center position of the end face of the optical fiber, find the tilt angle of the emitted light with respect to the normal direction of the front end face of the optical connector. The tilt angle of the optical fiber core axis with respect to the normal direction of the front end face of the optical connector is calculated from the tilt angle of the incident light and each refractive index of the air and the optical fiber core, and the tilt of the optical fiber with respect to the optical connector is calculated. To measure.

Further, the image pickup system is focused on one end face of the optical fiber, and the light emitted from the one end face of the optical fiber is imaged while the image pickup system is brought close to the front end face of the optical connector from the focused position. Obtaining the center position of the optical fiber end face at each distance of the imaging system, from the change in the distance to the optical connector front end face of the imaging system and the change in the center position of the optical fiber end face,
The inclination angle of the core axis of the optical fiber with respect to the normal direction of the front end face of the optical connector is obtained, and the inclination angle of the optical fiber is measured.

Here, the focusing of the image pickup system is performed with respect to the one end face of the optical fiber exposed on the front end face of the optical connector, at an angle normal to the front end face of the optical connector or at an angle in this normal line direction. It is performed by projecting light from a direction and detecting the reflected light.

Further, focusing of the image pickup system is carried out by imaging the light emitted from the one end face of the optical fiber while bringing the image pickup system close to the one end face of the optical fiber exposed on the front end face of the optical connector. After sufficiently approaching the front end face of the connector, while moving the imaging system away from the front end face of the optical connector, the light emitted from the one end face of the optical fiber is imaged, and the imaging system is located at a different distance from the front end face of the optical connector. The center position of the optical fiber end face at each distance of the imaging system is determined from the multiple imaged end faces of the optical fiber, and the change in the distance of the imaging system from the optical connector front end face when the imaging system is brought close to the optical connector front end face And the change in the center position of the end face of the optical fiber, the tilt angle of the core axis of the optical fiber with respect to the normal direction of the front end face of the optical connector is obtained, and the imaging system is moved away from the front end face of the optical connector. From the change in the distance to the front end face of the optical connector of the imaging system and the change in the center position of the end face of the optical fiber, the inclination angle of the emitted light with respect to the normal direction of the front end face of the optical connector is obtained, Determine the refraction point of the light from the angle of inclination of the light emitted from the end face of the optical fiber,
The steps of focusing on this point of refraction are also performed.

Further, while keeping the image pickup system sufficiently away from one end face of the optical fiber, the emitted light is imaged, the center position of the end face of the optical fiber at each distance of the image pickup system is obtained, and the change of the distance from the front end face of the optical connector of the image pickup system. And the change in the center position of the end face of the optical fiber, the tilt angle of the light emitted from one end face of the optical fiber is obtained, and from the tilt angle of the emitted light and the respective refractive indices of the air and the optical fiber core, the core of the optical fiber is calculated. The tilt angle of the axis is determined and the tilt angle of the optical fiber is measured.

While the imaging system is sufficiently close to one end face of the optical fiber, the light emitted from this one end face is imaged, the center position of the end face of the optical fiber at each distance of the imaging system is determined, and the front end of the optical connector of the imaging system is obtained. The tilt angle of the core axis of the optical fiber is obtained from the change in the distance to the surface and the change in the center position of the end surface of the optical fiber, and the tilt angle of the optical fiber is measured.

Further, the focusing position of the image pickup system is geometrically estimated from the optical system constituting the image pickup system, and the image pickup system is moved from this front end face from a position closer to the front end face of the optical connector than the estimated focus position. Image the light emitted from one end face of the optical fiber while moving away from it, and change the distance to the optical connector front end face of the imaging system and the center position of the optical fiber end face on the side closer to the optical connector front end face than the estimated focusing position. Of the optical fiber core axis from the estimated change in the optical fiber core axis, and the change in the distance from the optical connector front end face to the side farther from the optical connector front end face than the estimated focus position and the center position of the optical fiber end face. From the change of, the tilt angle of the light emitted from the one end face of the optical fiber is determined, and the refraction point of the light is determined from the tilt angle of the obtained core axis of the optical fiber and the tilt angle of the light emitted from the end face of the optical fiber.
The position of the end face of the optical fiber is obtained from this refraction point, and the tilt angle of the optical fiber is measured.

Further, the focus position of the image pickup system is geometrically estimated from the optical system constituting the image pickup system, and the image pickup system is brought closer to the front end face from a position farther from the front end face of the optical connector than the estimated focusing position. Meanwhile, the light emitted from one end face of the optical fiber is imaged, and the change in the distance from the front end face of the optical connector to the optical connector front end face and the center position of the optical fiber end face on the side farther from the front end face of the optical connector than the estimated focusing position. Of the optical fiber from one end face of the optical fiber, the distance from the front end face of the imaging system closer to the front end face of the optical connector than the estimated focusing position The tilt angle of the core axis of the optical fiber is determined from the change in the center position of the fiber end face, and the refraction point of the light is determined from the tilt angle of the core axis of the optical fiber and the tilt angle of the light emitted from the end face of the optical fiber. Light from the point Determine the position of an optic end faces, to measure the tilt angle of the optical fiber.

Further, the light emitted from this one end face is imaged while the image pickup system is brought close to or away from the one end face of the optical fiber, and the image is taken after the image pickup system is sufficiently close to or far from the front end face of the optical connector. The emitted light is imaged while the system is sufficiently distant from or close to the front end face of the optical connector, and a plurality of end face images of the optical fiber are picked up by the image pickup system located at different distances from the front end face of the optical connector. Obtain the center position of the optical fiber end face at each distance, and from the change in the distance to the optical connector front end face of the imaging system and the change in the center position of the optical fiber end face when the imaging system is brought close to the optical connector front end face, When the tilt angle of the core axis is calculated and the imaging system is moved away from the front end face of the optical connector, the change in the distance from the front end face of the optical connector to the center of the optical fiber end face Position, the tilt angle of the output light is determined, and the refraction point of the light is determined from the tilt angle of the core axis of the optical fiber and the tilt angle of the output light from the end face of the optical fiber. And the tilt angle of the optical fiber is measured.

[0016]

When light propagates from the medium a having the refractive index n _{a to} the medium _b having the refractive index n _b , there is a gap between the light incident angle θ _a and the light emitting angle θ _b with respect to the normal direction of the boundary surface of each medium. The following relationship holds.

N _a tan θ _a = n _b tan θ _{b If the} medium a is an optical fiber core and the medium b is air, then each medium boundary surface corresponds to the front end face of the optical connector, and the normal end face of the optical connector is The tilt angle of the optical fiber core axis with respect to the line direction corresponds to θ _a , and the tilt angle of the light emitted from the end face of the optical fiber corresponds to θ _b .

Here, z is set in the direction normal to the front end face of the optical connector.
If the x axis is taken as the axis, the direction orthogonal to this normal direction, the change in the distance from the front end face of the optical connector of the imaging system from the plurality of images of the optical fiber end face when the imaging system is moved away from the front end face of the optical connector. z and a change Δx in the center position of the end face of the optical fiber corresponding to this distance change Δz are obtained. The inclination angle θ _{b of the} light emitted from the end face of the optical fiber is tan θ _b =
It is calculated from the relationship of Δx / Δz. Further, from the tilt angle θ _{b of the} emitted light, the refractive index n _{a of the} optical fiber, and the refractive index n _{b of the} air, the tilt angle θ _a of the core axis of the optical fiber is
It is calculated by the above-described relational expression between the light incident angle θ _a and the light emitting angle θ _b . This also applies to the Y direction.

Also, by bringing the image pickup system closer to the front end face of the optical connector, the change Δz in the distance from the front end face of the optical connector of the image pickup system and the change Δx in the center position of the end face of the optical fiber.
And the tilt angle θ _a of the optical fiber core axis is tan θ
It is calculated immediately from the relationship of _a = Δx / Δz.

Further, from a plurality of images of the optical fiber end face when the imaging system is moved away from the optical connector front end face, the inclination angle θ _{b of the} light emitted from the optical fiber end face is tan θ _b = Δ
The tilt angle θ _a of the core axis of the optical fiber is tan θ _a = Δ calculated from the plurality of images of the end face of the optical fiber when the imaging system is brought close to the front end face of the optical connector.
It is calculated from the relationship of x / Δz. Therefore, the refraction point of light, that is, the position of the end face of the optical fiber is determined from the obtained tilt angle θ _a of the core axis of the optical fiber and the tilt angle θ _b of the light emitted from the end face of the optical fiber.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a perspective view showing the overall configuration of a core eccentricity measuring device to which the method of this embodiment is applied, and FIG. 3 is a block diagram showing its functional configuration.

As shown in FIG. 2, the optical connector 101 is set on a rotary stage 11 rotatable on a horizontal plane,
This rotary stage 11 is mounted on a Y-axis stage 12 that is linearly driven in the horizontal Y-direction,
2 is mounted on the X-axis stage 13 which is linearly driven in the X direction orthogonal to the Y direction. Optical connector 101
A microscope 22 having an objective lens 21 attached thereto is set above, and a CCD camera 23 is mounted on the microscope 22. Further, a reflective AF (autofocus) device 24 is attached to the side of the microscope 22, and these are attached to a Z-axis stage 14 movable in the vertical direction (Z direction).

On the other hand, the rotary stage 11 and the Y-axis stage 1
2, the side surfaces of the X-axis stage 13 and the Z-axis stage 14 that move in parallel are equipped with a length measuring device typified by a linear scale, and the movement is detected by the sensors 31 to 34 to generate a pulse corresponding to the movement amount. It is designed to output. Also,
A light source 40 is separately provided, and illumination light from the light source 40 is sent to the optical connector 101 via an optical fiber 41 or an optical lens (not shown).
This illumination light is transmitted through the guide pin hole 105 of the optical connector 101.
Or the optical fiber 41 inserted into the fiber hole 106 of the optical connector 101.

As shown in FIG. 3, the rotary stage 11 is driven by the rotary drive mechanism 51, the Y-axis stage 12 is driven by the Y-axis drive mechanism 52, the X-axis stage 13 is driven by the X-axis drive mechanism 53, and the Z-axis stage 14 is driven by Z. It is movable by an axis drive mechanism 54, and these drive mechanisms 51 to 54 are composed of stepping motors, etc.
Controlled by 5. In addition, the sensors 31 to 34
Output pulses are counted by the counter 35 and the movement amount is monitored. The rotary stage 11 is usually used in a fixed state in this embodiment. However, when the optical connector 101 is largely tilted with respect to the X and Y axes, it can be driven and used if necessary.

The output (image data) of the CCD camera 23 is sent to the image processing device 61 for contour detection and center position calculation, and is also sent to the image AF device 62 for focusing. The image processing device 61 and the image AF
The output of the device 62 is sent to the CPU 63 and appropriately displayed on the CRT 64. The CPU 63 is a reflection type AF device 24.
The light source 40A for illuminating the optical fiber 41 and the light source 40 for illuminating the guide pin hole 105 are controlled via the light source driver 42 while controlling the stage driver 55.
You are controlling B.

FIG. 4 shows the state of the optical connector 101 in the embodiment. Two guide pin holes 105 parallel to each other are formed on both sides, and a large number of fiber holes 106 are formed between them. The optical fiber 41 is inserted into the fiber hole 106, and the end face of the optical fiber 41 is exposed from the opening of the fiber hole 106 at the front end face of the optical connector 101. FIG. 1 shows the optical connector 10 shown in FIG.
1 is a partially enlarged sectional view of FIG. Since there is a clearance between the fiber hole 106 and the optical fiber 41, the core axis direction of the optical fiber 41 is inclined by the inclination angle θ _{a with} respect to the normal direction of the front end face of the connector as shown in the figure. Light source 40A
From the rear end of the optical fiber 41 through a lens (not shown), and is emitted from the one end face of the optical fiber 41 exposed at the front end face of the connector at an inclination angle θ _b . The inclination angle θ _a of the core axis of the optical fiber 41 is actually about 0.3 ° at maximum. Therefore, the boundary surface between the exposed end surface of the optical fiber 41 and the air can be approximated to the front end surface of the optical connector. If the optical refractive index of the core of the optical fiber 41 is n _a and the optical refractive index of air is n _b ,
The following relational expression holds.

N _a tan θ _a = n _b tan θ _b Therefore, based on the above premise, the inclination angle θ _a of the optical fiber 41 with respect to the optical connector 101 is measured by the method of this embodiment as follows. To be done.

First, the CCD camera 23 is focused on the core end face of the optical fiber 41 exposed on the front end face of the optical connector 101 as follows.

FIG. 5 shows the detailed structure of the reflective AF device 24. This is a focus detection device by the critical angle method, and light is incident from the normal direction of the surface to be measured (front end surface of the optical connector 101). The measurement light from the light source 241 is collimated by the collimator lens 242, is incident on the polarization beam splitter 243, and is reflected in the orthogonal direction. The plane of polarization of the reflected light is rotated by 45 ° by passing through the quarter-wave plate 244, and is focused by the condenser (or objective) lens 245.

Here, when the surface to be measured is at the focal position of the condenser lens 245 (state of the solid line), the reflected light passes through the same optical path and is collimated again by the condenser lens 245, and 1 /
The plane of polarization is further rotated through 45 ° through the four-wave plate 244. Thereby, the reflected light is reflected by the polarization beam splitter 243.
Since the planes of polarization are orthogonal to each other, the light passes through the polarization beam splitter 243 as it is and the critical angle prism 2
It is incident on 46. Here, since the critical angle prism 246 has an angle θ in the drawing as the critical angle, the incident light is totally reflected, and the reflected light is incident on the two-divided sensor 247. Therefore, it can be seen that light is equally incident on both light-receiving surfaces of the two-divided sensor 247, and the measured surface is at the in-focus position.

On the other hand, when the surface to be measured is separated from the reflective AF device 24 as shown by the dotted line in the figure, the reflected light after passing through the condenser lens 245 becomes focused light, and in this state, the critical angle prism. It is incident on 246. Then, the incident angle of the incident light on the reflecting surface of the critical angle prism 246 is equal to or greater than the critical angle θ on one side and equal to or less than θ on the opposite side.
Only the light having the critical angle θ or less is reflected and the two-division sensor 247
Detected by. Therefore, by comparing the detection levels on both the light receiving surfaces of the two-divided sensor 247, it is found that the measured surface is separated. On the contrary, when the surface to be measured is closer than the focus position, the output ratio of the two-divided sensor 247 is reversed, so it can be seen that the surface is approached. This enables focus detection.

In this critical angle method, as shown by the solid line in FIG. 6, the measuring light for focusing operation is supplied from the optical connector 101 from a direction substantially coaxial with the incidence of light from the light source 40 on the optical fiber 41.
The light is applied to the end face of the optical fiber 41 on the front end face of the optical fiber 41. In order to adopt this configuration, a wavelength-selective beam splitter 240 is provided on the optical path. That is, the beam splitter 240 is configured to transmit white light (solid line) from the light source 40 and reflect infrared light (e.g., wavelength 830 nm) from the light source 241 of the reflective AF device 24. As a result, the image pickup by the CCD camera 23 and the focusing operation by the reflective AF device 24 can be simultaneously executed.

Further, as shown by the alternate long and short dash line in FIG. 6, light from the light source 248 is incident on the oblique axis, that is, at a certain angle from the normal to the front end face of the optical connector 101, and the reflected light is imaged by the camera 249. Then, the focus may be detected. That is, in the present invention, not only the critical angle method as shown in FIG. 5 but also focus detection by another method, for example, the knife edge method or the astigmatism method can be used.

The wavelength of the incident light on the optical fiber 41, that is, the emission wavelength of the light source 40 is not particularly limited, but it is desirable that the wavelength is longer than the cutoff wavelength of the optical fiber 41. That is, as shown in FIG. 7, when the wavelength is longer than the cutoff wavelength, the single mode is set, and the intensity distribution of the light emitted from the optical fiber 41 becomes a Gaussian distribution ((a) in the same figure). Can be accurately determined. On the other hand, when the wavelength is shorter than the cutoff wavelength, the multimode type light intensity distribution shown in FIG. However, even in this case, by accurately focusing using the reflective AF device 24, it is possible to accurately measure the center of the core.

Next, from the focused position in this way, C
The light emitted from the core of the optical fiber 41 is imaged by the CCD camera 23 while the imaging system including the CD camera 23 is gradually or continuously separated from the front end face of the optical connector 101. The CCD camera 23 is located at a different distance from the front end face of the optical connector 101 by being moved away by the Z-axis drive mechanism 54, and the CCD is different at each distance.
An end face image of the optical fiber 41 is captured by the camera 23, and a plurality of end face images are obtained. The image processing device 61 stores the obtained end face image data in the memory and calculates the center position of the end face of the optical fiber at each distance of the imaging system as follows.

That is, in order to obtain the core center of the optical fiber 41, edge detection of the end face image is performed. In this edge detection, as shown in FIG. 8A, a change point, that is, an edge is obtained by checking the change in the brightness of the pattern on the end face in the X and Y directions.
A circle pattern may be detected from this combination of edges, but it may also be detected by a memory batch method as shown in FIGS. That is, the optical fiber 41
The light emitted from the CCD camera 2 is divided into a plurality of imaging ranges.
The image is captured in 3 and stored in the frame memory built in the image processing device 61. Then, a circle equation is calculated from the addresses corresponding to the edges by the least square method as shown in FIG. As a result, the coordinates of the center of the circle, that is, the center position of the core of the optical fiber 41 can be obtained. The calculation of the core center position is performed for each distance to the front end face of the optical connector of the image pickup system.

Here, as shown in FIG. 1, the optical connector 1
When the z-axis is taken in the normal direction of the front end face of 01 and the x-axis is taken in the direction orthogonal to this normal direction, the core center position of the optical fiber 41 at each distance of the imaging system obtained as described above is, for example, , As shown in FIG. That is, when the focus of the imaging system is on the front end face of the optical connector 101, the center position of the optical fiber core is shown in FIG. However, when the focus position of the image pickup system moves away from this in-focus position and is located at the position of the distance z ₁ from the front end face of the optical fiber, the center position of the core shifts from the actual center of the core indicated by the one-dot chain line, and is indicated by the dotted line. Appears to be in the position shown. This is because the optical fiber 41 is inclined as shown in FIG. 1 due to the clearance existing between the optical fiber 41 and the fiber hole 106. This shift is expressed as a distance x ₁ = z ₁ · tan θ _b using the inclination angle θ _{b of the} light emitted from the optical fiber 41 and the focal length z ₁ of the imaging system. When the imaging system is further away from the front end face of the optical connector and the focal point is at the position of the distance z ₂ , the core center of the optical fiber 41 is further displaced from the actual position shown by the alternate long and short dash line in FIG. ) Will be visible at the position indicated by the dotted line. Similarly, this deviation is the distance x ₂ =
It is expressed as z ₂ · tan θ _b .

Changes in distance from the center position coordinates of the optical fiber core to the front end face of the optical connector of the image pickup system.
z (for example, z ₂ −z ₁ ) and a change Δx (for example, the center position of the end face of the optical fiber corresponding to the change Δz in the distance).
x ₂ −x ₁ ) is obtained. Therefore, the inclination angle θ _{b of the} light emitted from the end face of the core of the optical fiber 41 is tan θ _b = Δx /
It is calculated from the relationship of Δz. Further, the tilt angle θ _a of the core axis of the optical fiber is calculated from the tilt angle θ _{b of the} emitted light, the core refractive index n _a of the optical fiber 41, and the refractive index n _{b of the} air by the above formula.

Therefore, according to the present embodiment, it is possible to measure the inclination angle of the optical fiber 41 with respect to the front end face of the optical connector with high accuracy in an actual use state in which the optical fiber 41 is inserted into the optical connector 101. Become. For this reason,
Product evaluation of the optical connector in the actual use state is accurately performed, and suitable optical coupling is realized.

In the above embodiment, the focusing of the image pickup system is performed by using the critical angle method, the knife edge method, the astigmatism method, or the like, but the method described below can also be used.

That is, the image pickup system includes the optical fiber 4 exposed on the front end face of the optical connector 101 by the Z-axis drive mechanism 54.
1 is brought close to one end face. Then, the image pickup system images the light emitted from the optical fiber core by the CCD camera 23 while approaching the front end face of the optical connector. After the imaging system is brought sufficiently close to the front end face of the optical connector, it is moved away from the front end face of the optical connector this time. Then, while the imaging system moves away from the front end face of the optical connector, the light emitted from the optical fiber core is CC
The D camera 23 takes an image. Therefore, the CCD camera 23 is located at a different distance from the front end face of the optical connector 101, and the optical fiber 4 exposed at the front end face of the optical connector 4 at each distance.
The core end surface of No. 1 is imaged. This core end face image is stored in the frame memory in the image processing device 61 from the CCD camera 23. As a result, a plurality of optical fiber core end face images are stored in the frame memory. The image processing device 61 detects the edge of the core end face from the imaged data as described above, and calculates the core center position coordinate of the optical fiber 41. The center position coordinates are the CCD camera 23.
It is calculated according to each distance from the front end face of the optical connector.

Next, the image processing device 61 changes the distance Δz of the image pickup system from the front end face of the optical connector and this distance change when the image pickup system is brought close to the front end face of the optical connector from the core center position coordinates. A change Δx in the center position of the end face of the optical fiber corresponding to Δz is calculated. That is, when the image pickup system is brought closer to the front end face of the optical connector from the in-focus position, the core center position moves in the negative direction of the x axis as shown in FIG. For example, when the focus position of the CCD camera 23 is −z ₁ , the core center position appears to be shifted to −x ₁ = −z ₁ · tan θ _a . When the CCD camera 23 is closer to the front end face of the connector and the focal position is at −z ₂ , the core center position appears to be further shifted to −x ₂ = −z ₂ · tan θ _a . Therefore, the distance change Δz can be obtained by calculating, for example, z ₂ −z ₁ , and the distance change Δx can be obtained by calculating, for example, x ₂ −x ₁ . The image processing device 61 obtains the inclination angle θ _a of the core axis of the optical fiber 41 with respect to the normal direction of the front end face of the optical connector from the relational expression tan θ _a = Δx / Δz.

Further, the image processing device 61 determines the change Δz in the distance from the front end face of the optical connector of the image pickup system and the change Δx in the center position of the optical fiber end face when the image pickup system is moved away from the front end face of the optical connector. Ask. When the image pickup system moves away from the front end face of the optical connector, the core center position moves in the positive direction of the x-axis, and the distance changes Δz and Δx are obtained from the already obtained core center position coordinates in the same manner as described above. The inclination angle θ _b of the emitted light with respect to the normal direction of the front end face of the optical connector is expressed by the relational expression tan θ _b =
Calculated from Δx / Δz.

The inclination angle θ _a of the core axis of the optical fiber 41 and the inclination angle θ _{b of the} light emitted from the end surface of the optical fiber 41 thus obtained are shown in the graph of FIG. That is, the horizontal axis of the graph is z taken in the direction normal to the front end face of the optical connector.
This graph corresponds to the axis, and the vertical axis of the graph corresponds to the x axis orthogonal to this normal direction. In this graph, the inclination angle θ _a of the core axis is represented by _a straight line A, and the inclination angle θ _b of the emitted light is represented by a straight line B. The intersection of these straight lines A and B is the contact surface between the end face of the optical fiber core and the air, that is, the light. The position coordinates corresponding to the inflection point of are given.

Therefore, the focusing operation can be performed by focusing the image pickup system on the obtained intersection coordinates, and thereafter, by performing the steps according to the above-described embodiment, the front end face of the optical connector is performed in the same manner as in the above-mentioned embodiment. Optical fiber tilt angle θ
_a is obtained.

Further, in the above embodiment, the case where the tilt angle of the optical fiber 41 is measured by moving the imaging system away from the front end face of the optical connector with the focusing position as a reference has been described. The tilt angle of the optical fiber 41 can also be measured by bringing the reference end closer to the front end face of the optical connector.

That is, as described above, the focus of the image pickup system is adjusted to the one end face of the optical fiber 41 exposed on the front end face of the optical connector 101, and the image pickup system is gradually changed to the front end face of the optical connector based on this focusing position. Or while approaching continuously, CC
The D camera 23 images the light emitted from the core end surface of the optical fiber 41. Therefore, the CCD camera 23 is located at a different distance from the front end face of the optical connector 101, and the core end face of the optical fiber 41 is imaged at each of these distances. The plurality of captured core end face images are stored in the frame memory in the image processing device 61. The image processing device 61 uses the imaged data to detect the edge position of the end face image as described above to obtain the center position coordinate of the optical fiber core. Then, from the obtained center position coordinates, a change Δz in the distance of the imaging system from the front end face of the optical connector and a change Δx in the center position of the optical fiber end face when the imaging system is brought close to the front end face of the optical connector are calculated. . When the image pickup system is brought close to the front end face of the optical connector, the core center position moves in the negative direction of the x-axis as described above. The image processing device 61 changes each of these distances Δ
Based on z and Δx, using the relational expression tan θ _a = Δx / Δz, the optical fiber 4 with respect to the normal direction of the front end face of the optical connector
The tilt angle θ _a of the core axis of 1 is obtained.

As described above, even if the image pickup system is brought closer to the front end face of the optical connector with the in-focus position as a reference, the change Δz in the distance from the front end face of the optical connector of the image pickup system and the change Δx in the center position of the end face of the optical fiber. And the tilt angle θ _a of the core axis of the optical fiber 41 is immediately calculated.

Next, a method of measuring the inclination angle of the optical fiber according to the second embodiment of the present invention will be described. In the first embodiment described above, the end face of the core is imaged and the tilt angle of the optical fiber is measured by moving the image pickup system away from or near the front end face of the optical connector based on the in-focus position. However, in this embodiment, the tilt angle of the optical fiber is measured without obtaining the focal position.

That is, by making the image pickup system sufficiently away from the front end face of the optical connector 101, the focus position of the image pickup system consequently becomes a positive direction of the z-axis (in the plus direction of the z-axis from the in-focus position shown by z = 0 in FIG. 1). (Upward direction). Therefore, even if the in-focus position is not known, the change Δz in the moving distance of the imaging system and the change Δx in the core center position corresponding to the change Δz in the distance can be obtained as described above. If the distance changes Δz and Δx are known, the optical fiber 4
The inclination angle θ _b of the emitted light from 1 is the relational expression tan θ _b = Δx /
Calculated by Δz. Therefore, as for the inclination angle θ _a of the core axis of the optical fiber 41, the obtained inclination angle θ _{b of the} emitted light and the optical refractive index n _a of the core of the optical fiber 41 and the optical refractive index n _{b of} air are described above. It is calculated by substituting in the formula.

Therefore, also in the second embodiment, the same effect as that of the first embodiment can be obtained, the product evaluation of the optical connector in the actual use state can be accurately performed, and the suitable optical coupling can be realized.

Further, in the above description of the measuring method in the second embodiment, the case where the image pickup system is moved away from the front end face of the optical connector has been explained, but the inclination angle of the optical fiber 41 can also be set by moving the image pickup system closer to the front end face of the optical connector. It is possible to measure

That is, by bringing the image pickup system sufficiently close to the front end face of the optical connector 101, the focus position of the image pickup system consequently becomes a negative direction of the z axis from the in-focus position shown by z = 0 in FIG. In the direction toward the bottom of the figure).
Therefore, even if the in-focus position is not known, the change Δz in the moving distance of the imaging system and the change Δx in the core center position corresponding to the change Δz in the distance can be obtained as described above. If the distance changes Δz and Δx are known, the optical fiber 41
The inclination angle θ _a of the core axis of is immediately obtained by the relational expression tan θ _a = Δx / Δz. Therefore, the effect similar to that of the first embodiment can be obtained only by bringing the image pickup system close enough to the end surface of the core.

Next, a method of measuring the tilt angle of the optical fiber according to the third embodiment of the present invention will be described. In the first embodiment, the image pickup system is moved starting from the in-focus position, and in the second embodiment, the image pickup system is moved without obtaining the in-focus position. In the third embodiment, the image pickup system is moved from the optical system. The focus position is estimated, the imaging system is moved starting from a position deviated from this focus position, and the tilt angle of the optical fiber is measured.

That is, the focus position of the image pickup system is geometrically estimated from the optical system forming the image pickup system, and the image pickup system is started from a position closer to one end face of the optical fiber 41 than the estimated focus position. Away from this end. Then, the light emitted from the end face of the core of the optical fiber 41 is imaged while keeping the distance. When the image pickup system is moved in this way, the focus position of the image pickup system moves from the minus side of the z axis shown in FIG. 1 to the plus side of the z axis via the focus position (z = 0). Therefore,
It is possible to obtain the change Δz in the moving distance of the imaging system on each of the negative side and the positive side of the z-axis and the change Δx in the core center position corresponding to the change Δz in the distance. The tilt angle θ _a of the core axis of the optical fiber 41 is calculated from the distance changes Δz and Δx obtained based on the movement of the focal position on the minus side of the z axis.
Is obtained by the relational expression tan θ _a = Δx / Δz. Also,
From the distance changes Δz and Δx obtained based on the movement of the focal position on the plus side of the z axis, the inclination angle θ _{b of the} light emitted from the optical fiber 41 is _expressed by the relational expression tan θ _b = Δx / Δz. I want it. Further, thus inflection point of the light to understand as described above from the inclined angle theta _b tilt angle theta _a and the outgoing of the core shaft thus determined positions of the light emitting end face of the optical fiber 41 is found.

The optical fiber tilt angle measuring method according to the third embodiment also accurately evaluates the product of the optical connector in the actual use state, and as a result, a suitable optical coupling is realized.

In the description of the third embodiment, the optical fiber 41 is used rather than the focus position geometrically estimated from the optical system.
I explained the case where the imaging system was moved away from the core end surface of the core as the starting point, but the core end surface was imaged while the imaging system was closer to this core end surface starting from the position farther from the core end surface than the estimated focusing position. It may be done. Also by imaging in this way, the distance changes Δz and Δx can be obtained on the positive and negative sides of the z axis, and the inclination angle θ _{a of} the core axis,
The inclination angle θ _b of the emitted light and the position of the light emitting end face are obtained.

Next, a fourth embodiment of the present invention will be described. In the above-described third embodiment, the focus position is estimated, and the image pickup system is moved in one direction starting from a position deviated from this focus position. However, in the fourth embodiment, the focus position is not estimated. , The inclination angle θ _a of the core axis of the optical fiber 41, each light emitting θ _b , and the position of the light emitting end face are obtained.

That is, the image pickup system is brought sufficiently close to the optical fiber core end face from an arbitrary position, and after sufficiently brought close thereto, this time, the image pickup system is sufficiently moved away from the core end face. Due to such movement of the image pickup system, the focus position of the image pickup system always passes through the in-focus position (z = 0) shown in FIG. 1 and moves on the positive and negative sides of the z axis. Therefore, as described above, from the distance changes Δz and Δx obtained by moving the focal point on the positive side of the z-axis, the light emission angle θ is obtained.
_b is obtained, and the core axis inclination angle θ _a is obtained from the distance changes Δz and Δx obtained by moving the focal position on the negative side of the z axis. Therefore, the light refraction point can be obtained from these inclination angles θ _a and θ _b, and the position of the light emitting end face can be found.

Further, the inclination angles θ _a and θ _{b and} the position of the light emitting end face can be found by moving the imaging system sufficiently away from the end face of the optical fiber core from an arbitrary position, and then sufficiently approaching the end face of the core.

Therefore, the inclination angle of the optical fiber can be measured by such a measuring method, the product of the optical connector can be evaluated, and the same effects as those of the above-mentioned respective embodiments can be obtained.

[0062]

As described above, according to the present invention, the change Δz in the distance from the front end face of the optical connector of the imaging system to the plurality of images of the end face of the optical fiber when the imaging system is moved away from the front end face of the optical connector. And the change Δx in the center position of the end face of the optical fiber corresponding to this distance change Δz can be obtained.
The inclination angle θ _{b of the} light emitted from the end face of the optical fiber is tan θ _b
= Δx / Δz. Further, from the tilt angle θ _{b of the} emitted light, the refractive index n _{a of the} optical fiber, and the refractive index n _{b of the} air, the tilt angle θ _a of the core axis of the optical fiber is the relational expression n _a tan θ _a = n _b tan Calculated by θ _b .

Further, by bringing the image pickup system closer to the front end face of the optical connector, the change Δz in the distance from the front end face of the optical connector of the image pickup system and the change Δx in the center position of the end face of the optical fiber.
And the tilt angle θ _a of the optical fiber core axis is tan θ
It is calculated immediately from the relationship of _a = Δx / Δz.

Further, from a plurality of images of the optical fiber end face when the imaging system is moved away from the optical connector front end face, the inclination angle θ _{b of the} light emitted from the optical fiber end face is tan θ _b = Δ
The tilt angle θ _a of the core axis of the optical fiber is tan θ _a = Δ calculated from the plurality of images of the end face of the optical fiber when the imaging system is brought close to the front end face of the optical connector.
It is calculated from the relationship of x / Δz. Therefore, the refraction point of light, that is, the position of the end face of the optical fiber is determined from the obtained tilt angle θ _a of the core axis of the optical fiber and the tilt angle θ _b of the light emitted from the end face of the optical fiber.

Therefore, there is provided an optical fiber tilt angle measuring method capable of highly accurately measuring the tilt angle of the optical fiber with respect to the front end face of the optical connector when the optical fiber is actually inserted into the optical connector. Therefore, the product evaluation of the optical connector in the actual use condition is performed accurately,
Suitable optical coupling will be realized.

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view of an optical connector to which an optical fiber tilt angle measuring method of an embodiment is applied.

FIG. 2 is a perspective view of an apparatus to which the optical fiber tilt angle measuring method of the embodiment is applied.

FIG. 3 is a block diagram of an apparatus to which the optical fiber tilt angle measuring method of the embodiment is applied.

FIG. 4 is a perspective view of an optical connector according to an example.

FIG. 5 is an explanatory diagram of focus detection by the critical angle method.

FIG. 6 is an explanatory diagram of focus detection by another method.

FIG. 7 is an intensity distribution chart of light emitted from an optical fiber.

FIG. 8 is an explanatory diagram of center position detection.

FIG. 9 is an explanatory diagram of the position movement of the center of the optical fiber core accompanying the movement of the imaging system.

FIG. 10 is a graph showing an optical fiber tilt angle θ _a and an outgoing light tilt angle θ _b with respect to the normal direction of the front end face of the optical connector.

FIG. 11 is a perspective view showing a conventional example.

[Explanation of symbols]

θ _a ... Optical fiber tilt angle, θ _b ... Emitted light tilt angle, 101
... optical connector, 105 ... guide pin hole, 106 ... fiber hole, 11 ... rotary stage, 12 ... Y-axis stage, 13
... X-axis stage, 14 ... Z-axis stage, 21 ... Objective lens, 22 ... Microscope, 23 ... CCD camera, 24 ... Reflective AF device, 40 ... Light source, 41 ... Optical fiber, 51 ... Rotation drive mechanism, 52 ... Y Axis drive mechanism, 53 ... X-axis drive mechanism,
54 ... Z-axis drive mechanism, 55 ... Stage driver, 61 ...
Image processing device, 62 ... Image AF device, 63 ... CPU, 6
4 ... CRT.

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[Procedure amendment]

[Submission date] September 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title: Optical fiber tilt angle measuring method and optical connector

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring an inclination angle of an optical fiber with respect to an optical connector and an optical connector measured by this method.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

The present invention provides an optical fiber tilt angle measuring method and a method for accurately measuring the tilt angle of the optical fiber with respect to the front end face of the optical connector when the optical fiber is actually inserted into the optical connector. An object of the present invention is to provide a measured optical connector, accurately evaluate the product of the optical connector in an actual use state, and realize suitable optical coupling.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Further, from a plurality of images of the optical fiber end face when the image pickup system is moved away from the optical connector front end face, the inclination angle θ _{b of the} light emitted from the optical fiber end face is tan θ _b = Δ
The tilt angle θ _a of the core axis of the optical fiber is tan θ _a = Δ, which is calculated from the relationship of x / Δz and is obtained from a plurality of images of the end face of the optical fiber when the imaging system is brought close to the front end face of the optical connector.
It is calculated from the relationship of x / Δz. Therefore, the refraction point of light, that is, the position of the end face of the optical fiber is determined from the obtained tilt angle θ _a of the core axis of the optical fiber and the tilt angle θ _b of the light emitted from the end face of the optical fiber. Further, an optical connector in which the optical fiber tilt angle in the actual use state is known can be obtained.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0065

[Correction method] Change

[Correction content]

Therefore, there is provided an optical fiber tilt angle measuring method capable of highly accurately measuring the tilt angle of the optical fiber with respect to the front end face of the optical connector when the optical fiber is actually inserted into the optical connector. Therefore, by using this measuring method, an optical connector in which the inclination angle of the optical fiber in the actual use state is known can be obtained. As a result, the product evaluation of the optical connector in the actual use state is accurately performed, and suitable optical coupling is realized.

Claims (12)

[Claims] 1. A first step of focusing an image pickup system on the one end face of an optical fiber held while one end face is exposed on a front end face of an optical connector, and the image pickup system is fixed from a position where the one end face is in focus. A second step of imaging the emitted light from the one end face of the optical fiber while keeping the optical fiber away from the front end face of the optical connector; and the optical fiber imaged by the imaging system located at a different distance from the front end face of the optical connector. A third step of obtaining a center position of the optical fiber end face at each distance of the imaging system from a plurality of end face images, a change in a distance of the imaging system with respect to the optical connector front end face, and a change in a center position of the optical fiber end face. And a fourth step of obtaining the inclination angle of the emitted light with respect to the normal direction of the front end face of the optical connector, and the inclination angle of the emitted light and the air and the optical fiber core. And a refractive index, the inclination angle measurement method of the optical fiber for an optical connector that includes a fifth step of obtaining an inclination angle of the core axis of the optical fiber with respect to the normal direction of the optical connector front face. 2. A first step of focusing an image pickup system on the one end face of an optical fiber held while one end face is exposed at a front end face of an optical connector; and the image pickup system from the position where the one end face is in focus. A second step of imaging light emitted from the one end face of the optical fiber while approaching the front end face of the optical connector; and a step of capturing the optical fiber imaged by the imaging system located at a different distance from the front end face of the optical connector. A third step of obtaining a center position of the optical fiber end face at each distance of the imaging system from a plurality of end face images, a change in a distance of the imaging system with respect to the optical connector front end face, and a change in a center position of the optical fiber end face. And a fourth step of obtaining the tilt angle of the core axis of the optical fiber with respect to the normal direction of the front end face of the optical connector. Measuring method. 3. In the first step, the focusing of the imaging system is in the normal direction of the front end face of the optical connector or in the normal direction to the one end face of the optical fiber exposed on the front end face of the optical connector. The method for measuring an inclination angle of an optical fiber according to claim 1 or 2, wherein the method is performed by projecting light from an oblique direction having an angle and detecting the reflected light. 4. In the first step, the focusing of the imaging system is performed by imaging the light emitted from the one end face of the optical fiber while bringing the imaging system close to the one end face of the optical fiber exposed at the front end face of the optical connector. Step, after the imaging system is sufficiently close to the front end surface of the optical connector, while distant the imaging system from the front end surface of the optical connector, imaging the light emitted from the one end surface of the optical fiber, Determining the center position of the end face of the optical fiber at each distance of the imaging system from a plurality of end face images of the optical fiber imaged by the imaging system located at different distances from the front end face of the optical connector; From the change in the distance of the imaging system with respect to the front end face of the optical connector and the change in the center position of the end face of the optical fiber when the optical fiber is brought close to the front end face of the optical connector. The inclination angle of the core axis of the optical fiber with respect to the normal direction of the optical connector front end face is obtained, and the change in the distance of the imaging system from the optical connector front end face when the imaging system is moved away from the optical connector front end face. From the change of the center position of the optical fiber end face, the step of obtaining the inclination angle of the emitted light with respect to the normal direction of the optical connector front end face, and the inclination angle of the obtained core axis of the optical fiber and the optical fiber end face from the 3. The method of measuring an inclination angle of an optical fiber according to claim 1, further comprising: determining a refraction point of the light from the inclination angle of the emitted light and focusing on the refraction point. 5. A first step of imaging light emitted from the one end face while sufficiently separating an imaging system from the one end face of the optical fiber held and exposed at the front end face of the optical connector. A second step of obtaining the center position of the end face of the optical fiber at each distance of the imaging system from a plurality of end face images of the optical fiber imaged by the imaging system located at different distances from the front end face of the optical connector; The inclination angle of the light emitted from the one end face of the optical fiber with respect to the normal direction of the optical connector front end face is obtained from the change in the distance of the imaging system with respect to the optical connector front end face and the change in the center position of the optical fiber end face. From the third step, the inclination angle of the emitted light and the respective refractive indices of the air and the optical fiber core, the core axis of the optical fiber with respect to the normal direction of the front end face of the optical connector. And a fourth step of obtaining the inclination angle of the optical fiber with respect to the optical connector. 6. A first step of imaging light emitted from the one end face while sufficiently bringing an imaging system close to the one end face of the optical fiber held while exposing the one end face to the front end face of the optical connector, A second step of obtaining the center position of the end face of the optical fiber at each distance of the imaging system from a plurality of end face images of the optical fiber imaged by the imaging system located at different distances from the front end face of the optical connector; A third step of obtaining an inclination angle of the core axis of the optical fiber with respect to a normal line direction of the front end face of the optical connector from a change of a distance of the imaging system with respect to the front end face of the optical connector and a change of a center position of the end face of the optical fiber; Method for measuring an inclination angle of an optical fiber with respect to an optical connector equipped with the. 7. A focus position of an image pickup system that matches the one end face of an optical fiber held while exposing one end face to the front end face of an optical connector is geometrically estimated from an optical system constituting the image pickup system, While keeping the imaging system away from the front end face from a position closer to the front end face of the optical connector than the estimated focusing position,
The first step of imaging the light emitted from the one end face, the change in the distance of the imaging system to the front end face of the optical connector and the optical fiber on the side closer to the front end face of the optical connector than the estimated focusing position. From the change in the center position of the end face,
A second step of obtaining an inclination angle of the core axis of the optical fiber with respect to the normal direction of the front end face of the optical connector; and the light of the imaging system on the side farther from the front end face of the optical connector than the estimated focusing position. A third step of obtaining an inclination angle of light emitted from the one end face of the optical fiber with respect to a normal direction of the optical connector front end face, based on a change in the distance to the connector front end face and a change in the center position of the optical fiber end face; A fourth step of determining a refraction point of light from the obtained inclination angle of the core axis of the optical fiber and the inclination angle of the light emitted from the end face of the optical fiber, and obtaining the position of the one end face of the optical fiber from the refraction point. A method for measuring an inclination angle of an optical fiber with respect to a provided optical connector. 8. A focus position of an image pickup system which fits the one end face of an optical fiber held while exposing one end face to the front end face of an optical connector is geometrically estimated from an optical system constituting the image pickup system, While bringing the imaging system closer to the front end face from a position farther from the optical connector front end face than the estimated focusing position,
A first step of imaging the light emitted from the one end face; a change in the distance of the imaging system to the front end face of the optical connector on the side farther from the front end face of the optical connector than the estimated focusing position; The second step of obtaining the inclination angle of the light emitted from the one end face of the optical fiber with respect to the normal direction of the front end face of the optical connector from the change of the center position of the end face, and the estimated optical position of the optical connector from the estimated focusing position. From the change in the distance to the optical connector front end face of the imaging system on the side close to the front end face and the change in the center position of the optical fiber end face,
From the third step of obtaining the inclination angle of the core axis of the optical fiber with respect to the normal direction of the front end face of the optical connector, and from the obtained inclination angle of the core axis of the optical fiber and the inclination angle of the light emitted from the end face of the optical fiber. A fourth step of determining a refraction point of light and determining a position of the one end face of the optical fiber from the refraction point. 9. A first step of imaging light emitted from the one end face of the optical fiber while bringing an imaging system close to the one end face of the optical fiber held while exposing the one end face to the front end face of the optical connector. A second step of imaging the light emitted from the one end surface of the optical fiber while sufficiently moving the imaging system farther from the front end surface of the optical connector after the imaging system is sufficiently close to the front end surface of the optical connector, A third step of obtaining the center position of the optical fiber end face at each distance of the imaging system from a plurality of end face images of the optical fiber imaged by the imaging system located at different distances from the front end face of the optical connector; From the change in the distance between the image pickup system and the front end face of the optical connector and the change in the center position of the end face of the optical fiber when the image pickup system is brought close to the front end face of the optical connector, The tilt angle of the core axis of the optical fiber with respect to the normal direction of the front end face of the optical connector is determined, and the change in the distance of the imaging system from the front end face of the optical connector when the imaging system is moved away from the front end face of the optical connector, and From the change of the center position of the end face of the optical fiber, a fourth step of obtaining the inclination angle of the emitted light with respect to the normal direction of the front end face of the optical connector, and from the obtained inclination angle of the core axis of the optical fiber and the end face of the optical fiber. And a fifth step of determining a refraction point of the light from the inclination angle of the emitted light and determining the position of the one end face of the optical fiber from the refraction point. 10. A first step of imaging the light emitted from the one end face of the optical fiber while keeping the imaging system away from the one end face of the optical fiber held and exposed at the front end face of the optical connector. A second step of imaging the light emitted from the one end face of the optical fiber while bringing the imaging system sufficiently close to the front end face of the optical connector after the imaging system is sufficiently far from the front end face of the optical connector, A third step of obtaining the center position of the optical fiber end face at each distance of the imaging system from a plurality of end face images of the optical fiber imaged by the imaging system located at different distances from the front end face of the optical connector; From the change in the distance of the image pickup system from the front end face of the optical connector and the change in the center position of the optical fiber end face when the image pickup system is brought close to the front end face of the optical connector. A change in the distance of the imaging system from the optical connector front end surface when the tilt angle of the core axis of the optical fiber with respect to the normal direction of the optical connector front end surface is obtained and the imaging system is moved away from the optical connector front end surface. And a change in the center position of the end face of the optical fiber, the fourth step of obtaining the inclination angle of the emitted light with respect to the normal direction of the front end face of the optical connector, and the inclination angle of the core axis of the obtained optical fiber and the optical fiber. A fifth step of determining a refraction point of light from the inclination angle of the light emitted from the end face and obtaining the position of the one end face of the optical fiber from the refraction point. 11. The optical fiber according to claim 1, wherein the wavelength of light incident on the optical fiber is longer than the cutoff wavelength of the optical fiber. Tilt angle measurement method. 12. The center position of the end surface of the optical fiber is obtained by collectively storing the imaged data of the light emitted from the optical fiber in a memory and detecting the boundary between the dark and light of the imaged screen after the image data is stored. Claim 1 to claim 1
The optical fiber tilt angle measuring method according to any one of 0.