JPH05248821A - Optical fiber sensor head and optical fiber sensor using the head - Google Patents

Abstract

PURPOSE:To obtain a side-view-type optical fiber sensor head, wherein the number of parts is small, the constitution is simple and the assembling and the adjustment are easy, and an optical fiber sensor using this optical fiber sensor head. CONSTITUTION:Detecting light 1, which is propagated in an optical fiber 13, is reflected from a reflecting surface 15 at a specified angle and emitted from a detecting window 16. A notch 18, which has a specified angle relation with the reflecting surface, is provided in a holder 14. A sensor head 10 can be readily provided and adjusted without adjusting the optical axis of the detecting light 1. The sensor head 10 can be used not only for light projection but also for light reception.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side-view type sensor head using an optical fiber and an optical fiber sensor to which the sensor head is applied.

[0002]

2. Description of the Related Art Hitherto, as a photoelectric sensor head using an optical fiber, there has been proposed a side-view type head as disclosed in, for example, Japanese Patent Application Laid-Open Nos. 1-26707 and 1-26708. A conventional example of the side-view type optical fiber sensor head will be described with reference to FIGS. 10 and 11 show the configuration of the sensor head 100, (a) is a lateral side view seen from the tip of the sensor head 100 in the longitudinal direction, (b).
FIG. 4 is a vertical sectional view. In the first conventional example shown in FIG. 10, the optical fiber 103 has the holding sleeve 1 at its end.
Further, inside the holding sleeve 104, a reflector 107 having a reflecting surface 105 is disposed at a position facing the emission port 103a of the optical fiber 103. A detection window 106 is formed in the holding sleeve 104 so that the reflection surface 105 faces the outside.

On the other hand, the second conventional example shown in FIG. 11 has a tip cap 108 having a reflecting surface 105 and a detection window 106.
Is connected to the tip of the holding sleeve 104, and the first
The sensor head 100 has the same function as that of the conventional example.

With the configurations of the first and second conventional examples described above, the detection light 1 propagated in the optical fiber 103 is irradiated from the emission port 103a of the optical fiber 103 to the reflection surface 105 in the sensor head 100, and its reflection. The surface 105 changes the direction of the optical axis so as to be perpendicular to the light guide path, and then the light is emitted from the emission window 106 to the outside of the sensor head 100. Thereby, even when the detection target is in a narrow space, the holding sleeve 104 and the tip cap 1
The detection work can be performed as long as there is a space in which 08 can be inserted.

[0005]

However, in the above-mentioned conventional example, since the reflector 107 having the reflecting surface 105 or the tip cap 108 is constituted by a member different from the holding sleeve 104, the number of parts is increased. ,Also,
Since the holding sleeve 104 and the tip cap 108 are cylindrical, it is difficult and complicated to assemble the reflecting surface 105 for adjusting the optical axis of the detection light 1 in a predetermined direction. In addition, the adjustment is required every time the sensor head is mounted in the field where the sensor head is used, so that the time loss in the detection work is large.

The present invention has been made to solve the above problems, and is composed of fewer parts,
Moreover, it is an object of the present invention to provide a side-view type optical fiber sensor head which is easy to assemble and install at a place of use and a sensor to which the sensor head is applied.

[0007]

In order to achieve the above-mentioned object, the invention according to claim 1 has an optical fiber for propagating incoming and outgoing light, and a cylindrical cavity into which an end of the optical fiber is inserted. The holding member is integrally formed on the inner wall of the holding member, and is formed on the outer wall of the holding member and the reflecting surface facing the end face of the optical fiber and inclined with respect to the cylindrical axis direction. An optical fiber sensor head having a positioning notch having a predetermined angular relationship with the reflecting surface.

The invention according to claim 2 is the optical fiber sensor head according to claim 1, characterized in that a collimating optical system is arranged between the end of the optical fiber and the reflecting surface.

Further, the invention according to claim 3 is the same as claim 1.
Alternatively, an optical fiber sensor including the optical fiber sensor head according to claim 2 is provided.

[0010]

According to the structure of claim 1, when the light is projected from the optical fiber sensor head, the outgoing light propagated in the optical fiber is applied to the reflection surface in the sensor head from the end of the optical fiber. The reflecting surface changes the direction of the optical axis with respect to the light guide path at a predetermined angle, and then the light is emitted to the outside of the sensor head. On the other hand, when light is received by the same optical fiber sensor head, the detection light incident inside the sensor head is irradiated on the reflection surface, and the direction of the optical axis is directed to the light guide path by the reflection surface as in the case of projection. After being changed by a predetermined angle, the light enters the optical fiber from the end of the optical fiber and propagates.

According to the second aspect of the invention, the collimate optical system arranged between the end of the optical fiber and the reflecting surface in the sensor head shapes the incident and outgoing light into parallel beams. ..

According to the third aspect of the invention, the sensor head can be arranged in a small space.

[0013]

The first to seventh embodiments of the present invention will be described below with reference to the drawings. 1 to 8 show the configuration of the optical fiber sensor head, and (a)
FIG. 3A is a lateral side view of the sensor head as seen in the longitudinal direction from the tip, and FIG. In each drawing,
Components having the same function are designated by the same reference numerals.

First, an embodiment corresponding to the invention described in claim 1 will be described with reference to FIG. In the figure, the optical fiber 13 is inserted into the cylindrical portion 14b of the holder 14 including the cylindrical portion 14a and the cylindrical portion 14b.
The optical fiber 13 has a core 11 and a clad 12 for propagating the detection light 1. Holder cylinder part 14a
Is formed with a reflecting surface 15 that faces the light exit port 13a of the optical fiber 13 and is inclined at a predetermined angle with respect to the cylindrical axis direction of the cylindrical portion 14b. Further, the reflecting surface 15 faces the outside. A detection window 16 is formed on the outer wall of 14. Further, a D-cut portion 18 having a predetermined angular relationship with the reflecting surface 15 is provided at the tip of the holder cylindrical portion 14a as a notch for installing the sensor head 10 at a predetermined location.

The reflecting surface 15 and the detecting window 16 are formed by abutting the cutting tool 2 from a predetermined direction on the central portion of the holder 14, as shown in the drawing. If the cutting tool 2 is a cemented carbide material, the cut surface can be used as it is as a mirror surface. If not, the mirror surface is obtained by polishing after cutting and is used as the reflection surface 15. Also, the D cut portion 1
8 is similarly formed using the cutting tool 2.

As described above, since the reflecting surface 15, the detection window 16 and the D-cut portion 18 are integrally formed on the holder 14, they are the same as those of the first and second conventional examples shown in FIGS. Moreover, the work of adjusting the arrangement of the reflection surface 15 and the detection window 16 is not necessary. Moreover, by cutting using the same tool 2, the respective forming positions are unlikely to shift, and the optical axis of the detection light 1 can be easily set in a predetermined direction.

On the other hand, when the sensor head 10 is mounted, a mounting hole corresponding to the cross-sectional shape of the holder 14 provided with the D cut portion 18 is formed at the mounting position, and the holder 14 is inserted into the mounting hole. By doing so, the sensor head 10 is installed.

With the above structure, the detection light 1 propagating in the optical fiber 13 is emitted from the emission port 13a of the optical fiber 13 to the reflecting surface 15, and the reflecting surface 15 causes the optical axis direction of the optical fiber 13. After being changed to a predetermined angle with respect to the inner light guide path, the light is emitted from the detection window 16 to the outside of the sensor head 10 and projected onto the detection target.

Next, a second embodiment corresponding to the invention described in claim 1 will be described with reference to FIG. In this embodiment, the outer shape of the optical fiber sensor head 10 is the same as that of the first embodiment, but the holder 14 is made of a plastic or metal molded product. When the holder 14 is made of plastic, it is necessary to form a mirror surface on the reflection surface 15 by plating or vapor deposition. When the holder 14 is made of metal, a mirror surface can be obtained by lightly polishing the reflecting surface 15.

In the first and second embodiments, the D-cut portion 18 is provided as a notch in order to facilitate the installation of the sensor head 10. However, this notch has a D-cut on one side of the holder 14. Not only partially cut into a letter shape,
Partially cut both sides as shown in Figure 3,
As shown in FIG. 4, both sides of the holder 14 may be formed by cutting the entire surface in the longitudinal direction.

Next, a third embodiment of the invention described in claim 1 will be described with reference to FIG. The present embodiment is an example in which the sensor head 10 is constituted by the prismatic holder 14. The holder 14 includes a prism portion 14a and a prism tube portion 14b.
And a cylindrical cavity is formed in the rectangular tube portion 14b, and the optical fiber 13 is inserted into the cavity.
The prismatic holder 14 can be formed by either the cutting process shown in the first embodiment or the forming process shown in the second embodiment. Depending on the intended use of the sensor head 10, such a prismatic configuration may be easier to install at the place of use.

Next, a fourth aspect corresponding to the invention of claim 2
An example will be described with reference to FIG. In this embodiment, a collimating optical system is applied on the light guide path of the detection light 1. In the holder 14, a collimator lens unit 61 is arranged between the light emitting port 13 a of the optical fiber 13 and the reflecting surface 15. The lens unit 61 is composed of a gradient index lens 62 for converting the detection light 1 into a beam, and a slit member 63 provided on the surface of the lens 62 facing the light exit port 13a. The slit member 63 has a minute hole 64 for allowing the detection light 1 to pass therethrough.

With the above structure, the detection light 1 propagates in the optical fiber 13, is emitted from the light emission port 13a, and then is collimated by passing through the slit member 63 and the gradient index lens 62 to be thin. The light is shaped into a beam and is applied to the reflecting surface 15. After that, the first
As in the third to third embodiments, the direction of the optical axis of the detection light 1 is changed by the reflecting surface 15, and the detection light is projected from the detection window 16 onto the detection target.

By collimating the detection light 1 as in this embodiment, optical noise can be reduced and the directivity of the detection light 1 can be improved, so that a sensor having a high resolution can be constructed. It will be possible. In addition,
As the collimator lens, a general lens can be used in addition to the gradient index lens as described above.

Next, a fifth embodiment will be described with reference to FIG. This embodiment is the same as the second embodiment except that the detection window 16 is filled with a transparent resin 71. When the sensor head 10 is used in an environment with a large amount of dust and dirt, the dust and dirt and the like can be detected from the detection window 16 through the sensor head 10.
May invade inside and adhere to the reflective surface 15 and the like.
On the reflecting surface 15 to which dust or dirt adheres, the reflectance decreases or the detection light 1 is diffusely reflected, so that the detection function of the sensor deteriorates, but in the present embodiment, such a problem can be prevented.

Although the above-mentioned first to fifth embodiments show the light-projecting type sensor head, the invention according to claim 1 or 2 is not limited to the light-projecting type, and for example, is shown in FIG. It is also possible to apply to a reflective sensor head as in the sixth embodiment. In the sensor head 10 according to the sixth embodiment, the optical fiber 83 for receiving light is provided in the holder 14 along with the optical fiber 13 for projecting light. The light receiving optical fiber 83, like the light projecting optical fiber 13, is composed of a core 81 and a clad 82, and the detection light 1 is attached to the end thereof.
Has an entrance 83a for receiving the light.

Regarding light projection, the detection light 1 emitted from a light projecting device (not shown) is the optical fiber 1 for light projection.
3 is radiated to the outside of the sensor head 10 through the detection window 16 after being propagated through the inside of the optical fiber 13 and irradiated to the reflecting surface 15 from the emitting port 13a of the optical fiber 13 and the direction of the optical axis is changed by the reflecting surface 15. Then, the light is projected onto the detection target.

On the other hand, regarding the light reception, the detection light 1 reflected by the detection target passes through the detection window 16 and the sensor head 10.
Of the optical fiber 83 after being reflected on the reflection surface 15 and guided to the light entrance optical fiber 83 through the light entrance 83a. Light receiving device (not shown)
Is propagated to.

Further, the above-mentioned first to fifth embodiments can be used for receiving light by the same structure as for projecting light. That is, by configuring the optical fiber 13 in the first to fifth embodiments as a light receiving optical fiber, the detection light 1 reflected by the detection target is incident on the optical fiber 13 via the detection window 16 and the reflection surface 15. Then, the optical fiber 13 propagates the light to a light receiving device (not shown).

The embodiments according to the inventions of claims 1 and 2 have been described above. By using these sensor heads, even when the detection target is in a narrow space, the detection work can be performed as long as the holder 14 can be inserted.

Next, a seventh embodiment corresponding to the invention described in claim 3 will be described with reference to FIG. In the present embodiment, the optical fiber sensor 70 including the sensor head 10 according to the first embodiment is used for measuring the water level in the pipe 91. In the figure, an optical fiber sensor head 10 is attached to the tip of an optical fiber 13 arranged in a pipe 91.
1 is installed at a predetermined position.

An installation hole 92 corresponding to the shape of the sensor head 10 is provided at the installation location, and the tip portion of the sensor head 10, that is, the D-cut portion, is fitted into the installation hole 92, so that the sensor head is installed. It can be easily adjusted so that 10 can project the detection light 1 in a predetermined direction.

With the above structure, a light projecting device (not shown)
The detection light 1 emitted from the optical fiber 13 is propagated to the sensor head 10 by the optical fiber 13, is projected from the detection window 16 of the sensor head 10 to the water surface 93 which is a detection target below, and its reflected light is a light receiver (not shown). The received light is analyzed by the receiver to analyze the amount of received light.
The height of can be detected.

Needless to say, the invention according to claim 3 is applicable not only to the water level measuring sensor as in the seventh embodiment but also to various sensors. Also, depending on the usage environment and application of those sensors, as described above, the holder shape, the light projection type, the reflection type, and the like should be used properly, and furthermore, the detection window should be filled with resin to prevent contamination. Thus, it is possible to configure a sensor that is more suitable for the purpose.

[0035]

As described above, according to the first aspect of the present invention, there is provided an optical fiber sensor head applicable to any of a light projecting type, a reflective type, and a light receiving type, which guides detection light. A reflecting surface for changing the optical path is formed integrally with a holder for holding an optical fiber, and a notch having a predetermined angular relationship with the reflecting surface is provided on the outer wall of the holder for positioning. Therefore, the sensor head can be easily configured and installed without shifting the optical axis, and the assembling work is reduced.

According to the second aspect of the invention, in the sensor head, the collimate optical system disposed between the end of the optical fiber and the reflecting surface shapes the detection light into a parallel beam. Therefore, it is possible to improve the directivity of the detection light and improve the detection accuracy of the sensor head.

Further, according to the invention of claim 3, since the sensor head which can be easily arranged in a small space is used, it is possible to provide a highly accurate sensor applicable to various purposes. ..

[Brief description of drawings]

FIG. 1 shows a configuration of an optical fiber sensor head according to a first embodiment of the present invention, (a) is a lateral side view, and (b) is a longitudinal sectional view.

FIG. 2 shows a configuration of an optical fiber sensor head according to a second embodiment of the present invention, (a) is a lateral side view, and (b) is a longitudinal sectional view.

3A and 3B show a configuration of an optical fiber sensor head in which the shape of the notch is changed in the first and second embodiments, FIG. 3A is a lateral side view, and FIG. 3B is a longitudinal sectional view.

4A and 4B show a configuration of an optical fiber sensor head in which the shape of the cutout is changed in the first and second embodiments, FIG. 4A is a lateral side view, and FIG. 4B is a vertical sectional view.

5A and 5B show a structure of an optical fiber sensor head according to a third embodiment of the present invention, wherein FIG. 5A is a lateral side view and FIG. 5B is a longitudinal sectional view.

6A and 6B show a structure of an optical fiber sensor head according to a fourth embodiment of the present invention, wherein FIG. 6A is a lateral side view and FIG. 6B is a vertical sectional view.

FIG. 7 shows a configuration of an optical fiber sensor head according to a fifth embodiment of the present invention, (a) is a lateral side view and (b) is a longitudinal sectional view.

8A and 8B show a configuration of an optical fiber sensor head according to a sixth embodiment of the present invention, FIG. 8A is a lateral side view, and FIG. 8B is a longitudinal sectional view.

FIG. 9 is a schematic diagram showing the configuration and usage of an optical fiber sensor according to a seventh embodiment of the present invention.

FIG. 10 shows a configuration of an optical fiber sensor head of a first conventional example, (a) is a lateral side view, and (b) is a longitudinal sectional view.

FIG. 11 shows a configuration of an optical fiber sensor head of a second conventional example, (a) is a lateral side view, and (b) is a longitudinal sectional view.

[Explanation of symbols]

 1 Detecting Light 10 Optical Fiber Sensor Head 13 Optical Fiber 15 Reflecting Surface 16 Detecting Window 18 D Cut Part (Notch) 61 Collimating Lens Unit (Collimating Optical System) 70 Optical Fiber Sensor

Claims (3)

[Claims] 1. An optical fiber for propagating incoming / outgoing light, and a holding member having a cylindrical cavity into which an end of the optical fiber is inserted, the holding member being integrally formed on an inner wall thereof. A reflecting surface facing the end face of the optical fiber and inclined with respect to the cylindrical axis direction; and a positioning notch formed on the outer wall of the holding member and having a predetermined angular relationship with the reflecting surface. An optical fiber sensor head. 2. The optical fiber sensor head according to claim 1, further comprising a collimating optical system disposed between the end of the optical fiber and the reflecting surface. 3. An optical fiber sensor comprising the optical fiber sensor head according to claim 1 or 2.