JPS63168529A - Inspection of optical fiber connector - Google Patents

Abstract

PURPOSE:To measure an optical fiber angle and an angle of inclination of an end face separately, by projecting a reflected light of an irradiation light with a specified direction from an emitting end face and the irradiation light from an incident end face on a screen provided at the right angle to a ferrule at a specified distance from the emitting end face to perform a required computation. CONSTITUTION:Light incident parallel with the shaft of a ferrule 2 through a light source 7, a lens 9 and a half mirror 10 is reflected on an emitting end face of the ferrule 2 and forms an image at a position corresponding to an angle of inclination of the emitting end face on a screen 6 set at the right angle to the shaft of the ferrule 6 at a specified distance therefrom 2. On the other hand, light from a light source 12 incident into an incident end face of an optical fiber of the ferrule through an optical fiber 1 is varied in the direction of refraction according to the angle of the optical fiber on the side of the emitting end face to form an image on the screen 6. This enables computation and calculation of the angle of optical fibers and the angle of inclination of the ferrule end face separately and independently from the positions of these images on the screen 6 and the distance between the ferrule 2 and the screen 6.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method of inspecting connectors coupled to the ends of optical fibers for imperfections.

[Conventional technology]

Since optical fibers are connected to other optical fibers and equipment through connectors, the integrity of the connectors is important. Therefore, a method of inspecting the imperfection of a ferrule of an optical fiber connector has been proposed, for example, in Japanese Patent Laid-Open No. 58-31858. In this conventional inspection method, the ferrule is accurately held by a groove block, and the light that has propagated through the optical fiber is emitted from the end face of the ferrule and projected onto a screen, while the ferrule is rotated to draw a circular trajectory. By determining , the angle α of the optical fiber with respect to the mechanical center axis of the ferrule is measured. That is,
As shown in FIG. 3, when the optical fiber 1 is inserted into the center hole of the cylindrical ferrule 2 and fixed with adhesive 3, the center axis of the optical fiber 1 is relative to the mechanical center axis of the ferrule 2. Assuming that the ferrule 2 is tilted by an angle α, if the ferrule 2 is rotated about its central axis, the projected image of the light emitted from the optical fiber 1 onto the screen will draw a circular locus. The radius of this circular locus corresponds to the angle α. Therefore, by measuring the radius of this circular locus, this angle α can be determined.

[Problems to be solved by the invention]

However, the above-mentioned conventional inspection method has a problem that it remains insufficient because the radius of rotation of the projected image does not necessarily depend only on the angle α. For example, suppose that the end face of the ferrule 2 is inclined at an angle β together with the end face of the optical fiber 1 as shown in FIG. At this time, even if the angle α of the optical fiber 1 with respect to the central axis of the ferrule 2 is O, the incident angle with respect to the end face is β, which is not a right angle, so it will be refracted according to Snell's law, so the emitted light will change at an angle direction of ε (nsinβ・sinε
, n is the refractive index in the optical fiber 1). An object of the present invention is to provide an optical fiber connector inspection method that can separately measure the angle of the optical fiber and the angle of inclination of the end face.

[Means to solve the problem]

In the optical fiber connector inspection method of the present invention, a ferrule and a screen are arranged so that the mechanical center axis of the ferrule is perpendicular to the screen, and the end surface of the optical fiber is irradiated with light parallel to the ferrule center axis. Project the reflected light onto the screen and measure its projection position, emit the light that has propagated through the optical fiber from the end face, project the emitted light onto the screen, and measure its projection position. Then, by using the known distance from the end face to the screen, the known position of the ferrule mechanical center axis on the screen, and the two measured projection positions,
The present invention is characterized in that the direction and angle of the central axis of the optical fiber with respect to the mechanical central axis of the ferrule and the inclination direction and angle of the end face are calculated using the following law.

[For production]

The mechanical center axis of the ferrule can be determined by various methods. Therefore, the ferrule is placed so that the distance from the screen to the end face of the ferrule is a predetermined distance, and the center axis of the ferrule is perpendicular to the screen.
Light parallel to the central axis is irradiated onto the end face of the optical fiber, and the reflected light is projected onto a screen. By measuring this projection position, since the distance from the end face to the screen is known, the inclination direction and angle of the end face can be calculated. Furthermore, when the light that has propagated through the optical fiber is emitted from the end face of the optical fiber located at the end face of the ferrule, the direction of the light emitted depends on the inclination of the optical fiber itself and is refracted according to Snell's law. Therefore, it also depends on the inclination of the end face. Therefore, by measuring the projection position of this emitted light onto the screen, the inclination direction and angle of the end face have already been calculated as described above, and using this, the angle of the optical fiber itself can be calculated based on Snell's law. can do.

【Example】

In one embodiment of the invention, as shown in FIG. 1, the ferrule 2 to which the optical fiber 1 is fixed is held by the V-groove block 4 for measurement. Adjustments are made to keep the angle accurately perpendicular to the screen 6. Therefore, a reference gauge with an accurate end face perpendicularity and approximately the same diameter as the ferrule 2 is placed in this groove. Then, light is emitted from the light source 7, the shutter 8 is opened, the light is focused by the lens 9, and is reflected by the half mirror 10 to illuminate the end face of the reference gauge. Then, the light reflected by the end face of the reference gauge passes through the half mirror 10 and is projected onto the screen 6. In this state, the reference gauge is rotated within the V-groove, and the stage 5 is adjusted so that the image projected onto the screen 6 does not rotate. This stage 5 holds the V-groove block 4, and is movable in each direction of X, Y, and Z.
It is equipped with a tilting mechanism so that it can be tilted in any direction. With this stage 5 adjustment,
When the projected image stops rotating, the grooves can be kept perpendicular to the screen 6. The position of the projected image at this time is defined as the origin on the X-Y coordinates. In addition, half mirror 1
It is assumed that the light reflected at 0 is adjusted in advance so that it goes perpendicular to the screen 6. Next, while irradiating the light reflected by half mirror 10,
The ferrule 2 to be inspected is placed in the groove 2, and light is incident on the fiber 1 from the end face of the ferrule 2. Then, the light propagated through the optical fiber 1 is guided to the power meter 13 by the switch 11, and while observing the power meter 13, the position of the stage 5 is adjusted in X, Y, etc. so that the reading becomes maximum.
Move in the Z direction. Thereby, the beam spot of the light irradiated through the half mirror 10 comes to hit the core of the optical fiber 1. At this time, the position (Xl, Yt) of the image formed by the light reflected by the end face of the optical fiber 1 projected onto the screen 6 is measured. After that, the shutter 8 is closed, and the switch 11 is closed.
is switched so that the light from the light source 12 enters the optical fiber 1 and is propagated. The light propagated through the optical fiber 1 is emitted from the end face of the ferrule 2, and is emitted from the half mirror 10.
and is projected onto the screen 6. Therefore, the position (X2, Y 2 ) of this projected image is measured. Next, the following calculations are performed using these measured values X1, Yl, X2, and Y2. Here, it is assumed that the distance from the end face of the ferrule 2 to the screen 6 has been measured in advance. As shown in Figure 2, the direction cosine of the mechanical center axis of ferrule 2 is (ar, C2, C3).
, if the direction cosine of the end face normal is (br, bz, b3) and the direction cosine of the emitted light is (CI, C2, C3), then al=a2=Q, C3=1, b 1=X 1/L + X 1+ Y 1b2
It can be expressed as =Yt/r stone Ttsu Regarding the inclination β of the end face with respect to the central axis of the ferrule 2, the relationship β=cos−1(alb1+a2b2+a3b3) holds, so that the inclination β of the end face can be determined from this. Next, the angle α between the central axis of the ferrule 2 and the central axis of the optical fiber 1 is calculated. First, if the angle between the end face normal and the emitted light is δ, then δ=cos-' (b 1c 1+ b 2C2+ b
3C3). If the direction cosine of the central axis of the optical fiber 1 is (dl, C2, dx), then Sne
According to ll's law, 7 = sin'' ((sin δ)/n), where γ is the angle of incidence of light on the end surface, and ci = n (di-bi cos7) + bi 1-n
1-cos 71=1.2.3, the direction cosine di(C
4, 2, 3). In this way, the center a of the optical fiber 1
=cos-' (a1dl+a2d2+a3d3). All of the above operations can be performed by controlling the switch 11 and shutter 8 by computer, automatically adjusting the stage 5 based on the output of the power meter 13, and reading the position of the projected image on the screen 6 using a position measuring device. It is also possible to do this automatically and then perform the above calculations automatically. In addition, the focal length of the lens 9 is selected to set the spot diameter to the core diameter or beam field diameter of the optical fiber 1, and the light source 7
By reflecting the light from the half mirror 10 and entering the optical fiber 1, monitoring the intensity of the propagated light with the power meter 13, and measuring the change in the measured value by rotating the ferrule 2 to be inspected, It is also possible to measure the amount of eccentricity of the core (the spot diameter is, in the case of an aberration-free lens,
where f is the focal length, D is the beam diameter, and ^ is the wavelength, 0.6
1X (f/D)^).

【Effect of the invention】

According to the optical fiber connector inspection method of the present invention, the inclination of the optical fiber itself and the inclination of the end face can be inspected separately. Moreover, it can be easily inspected and can be automatically measured. Furthermore, by observing whether there are irregularities such as diffraction fringes or dark lines in the projected image, it is possible to easily check for breaks in the optical fiber. Furthermore, by adding some mechanisms, it is also possible to measure the eccentricity of optical fibers.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of one embodiment of the present invention, FIG. 2 is a schematic diagram for explaining the direction of light at the end face, and FIG.
The figure is a sectional view for explaining a conventional example, and FIG. 4 is a schematic diagram for explaining the path of light when the end face is inclined. DESCRIPTION OF SYMBOLS 1... Optical fiber, 2... Ferrule, 3... Adhesive, 4... V groove block, 5... Stage, 6...
...Screen, 7.12...Light source, 8...Shutter, 9...Lens, 10...Half mirror-111
...Switch, 13...Power meter.

Claims (1)

[Claims] (1) Arrange the ferrule and screen so that the mechanical center axis of the ferrule is perpendicular to the screen, irradiate the optical fiber end face with light parallel to the ferrule center axis, and reflect the light from the end face onto the screen. The light propagated through the optical fiber is emitted from the end face, the emitted light is projected onto the screen, the projected position is measured, and the light propagated through the optical fiber is projected onto the screen from the known end face. Using Snell's law, the direction of the optical fiber's central axis relative to the ferrule's mechanical central axis and the known position of the ferrule's mechanical central axis on the screen and the two measured projection positions are determined. An optical fiber connector inspection method characterized by calculating an angle, an inclination direction and an angle of an end face.