JPH0720341A - Optical fiber terminal unit - Google Patents

Abstract

PURPOSE:To obtain an optical fiber terminal unit having excellent directivity, steep in the light shielding characteristic of an object to be detected, and high in position detecting accuracy. CONSTITUTION:This unit is attached to the end of an optical fiber so that illuminating light of outgone from a light-transmitting optical fiber 1 and transmitted light is entered into a light-receiving optical fiber 2. The unit having such condition is provided with respective reflection surfaces 4 opposed to the end faces of the optical fibers 1 and 2 and a light-receiving window 5 and a light-transmitting window 6, and holder parts 3 holding the end of each optical fiber and each reflection surface inside and having a U-shaped cross section. A pin hole 7 is formed on each of the windows 5 and 6, and acts as a diaphragm for adjusting the cross section of the entering light and the outgoing light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end structure of an optical fiber, and more particularly, to an optical fiber terminal unit in which a reflecting surface is attached to an end of the optical fiber to allow light to enter and / or exit the optical fiber. .

[0002]

2. Description of the Related Art Conventionally, for example, an optical fiber end structure such as an optical fiber sensor head is one in which a cap is attached to the end of the optical fiber from which the cable covering material is removed and the end surface of the optical fiber is subjected to a predetermined treatment. In the transmission type optical fiber sensor head using such an optical fiber terminal, the light emitted from the light source and propagating in the optical fiber for light transmission is emitted from the end face of the optical fiber, and the transmitted light from the object is The light enters from the end face of the optical fiber, and the light receiving optical fiber propagates and detects this light.

[0003]

However, if the light is directly emitted from the end face of the optical fiber, or if the light is directly incident on the end face of the optical fiber, the emitted light spreads.
Further, ambient light having an off angle may be received. On the other hand, it has been proposed to dispose an optical element, for example, a cylindrical lens at the tip facing the end face of the optical fiber, but it does not necessarily have good directivity. Therefore, when the detection target passes through the inspection area, the light shielding property of the target is gentle and the position detection accuracy is not necessarily high.

The present invention has been made on the basis of the above background, and an object thereof is an optical fiber terminal having a good directivity, a light-shielding characteristic of an object to be detected being steep, and a position detecting accuracy being high. Is to provide a unit.

[0005]

The above problems can be solved by the present invention. That is, an optical fiber terminal unit according to the present invention is an optical fiber terminal unit that is attached to an end portion of an optical fiber, emits illumination light from a light transmitting optical fiber, and makes transmitted light enter a light receiving optical fiber. A reflecting surface facing the end face and the window of the optical fiber for light and receiving light,
A diaphragm having a holder for internally holding each optical fiber end and a reflecting surface, and providing a pinhole in a window for light reception and light transmission, and the pinhole adjusting a cross section of incident light and emitted light. It is characterized by acting as.

[0006]

The present invention having the above construction operates and operates as follows. In the optical fiber terminal unit of the present invention, the end portion of the optical fiber is held by the holder portion, and the light emitted from the light source and propagating in the optical fiber is emitted from the end face of the optical fiber terminal of the holder portion. Then, change the optical path of the light laterally on the reflecting surface facing the end face of the optical fiber, and adjust the cross section of this outgoing light with the pinhole formed in the window for light transmission,
It is emitted as illumination light.

This illuminating light illuminates the detection area and blocks light when the object to be detected is present, and transmits light when it does not exist. The pinhole formed in the light receiving window adjusts the cross section of the transmitted light from the object to remove unnecessary disturbance light.
As a result, light having more directivity changes in the direction of the end face of the optical fiber at the reflecting surface facing the pinhole, enters from the end face of the light receiving optical fiber, and propagates in the optical fiber.

[0008]

The present invention will be specifically described with reference to the following examples. FIG. 1 is a sectional view of an optical fiber terminal unit (transmission type optical fiber sensor head) according to an embodiment of the present invention. The optical fiber terminal unit of this aspect is mounted on the end portion of the optical fiber, emits illumination light from the light transmitting optical fiber 1, and makes transmitted light enter the light receiving optical fiber 2. In the optical fiber terminal unit of this aspect, the reflecting surfaces 4 facing the end faces of the transmitting and receiving optical fibers 1 and 2 and the windows 5 and 6, and the end portions and reflecting surfaces of the optical fibers are internally provided. A holder part 3 having a U-shaped cross section for holding is provided, and each of the light receiving window 5 and the light transmitting window 6 has a pinhole 7, and the pinhole acts as a diaphragm for adjusting the cross section of the incident light and the emitted light. . In this aspect, the cross-sectional shape and size of the diaphragm can be appropriately changed depending on the application.

The optical fiber terminal unit of this aspect operates as follows. In this optical fiber terminal unit, the light emitted from the light source and propagating in the optical fiber 1 for light transmission holds the end portion of the optical fiber 1 for light transmission by the holder part 3,
The light is emitted from the end face of the holder portion 3 at the end of the optical fiber 1 for light transmission. Next, the optical path of the light is changed laterally by the reflecting surface 4 facing the end face of the light transmitting optical fiber 1, and the cross section of the emitted light is adjusted by the pinhole 7 formed in the light transmitting window 5 for illumination. It is emitted as light.

This illuminating light illuminates the detection area and blocks light when the object to be detected is present, and transmits light when the object is not present. The pinhole 7 formed in the light receiving window 6 adjusts the cross section of the transmitted light from the target object to remove unnecessary disturbance light. As a result, more directional light is generated in the pinhole 7
Is changed to the direction of the end surface of the optical fiber 2 for light reception, the light is incident from the end surface of the optical fiber 2 for light reception, and propagates in the optical fiber 2.

Using the transmission type optical fiber sensor head according to this example and the transmission type optical fiber sensor head of the comparative example in which no pinhole was formed in the window, the respective light shielding characteristics were evaluated. The results are shown in FIG. As can be understood from this figure, in the sensor head of the example, the light-shielding characteristics are steep, the light amount rate changes abruptly due to the movement of the object to be detected, and the position detection accuracy is high. On the other hand, in the sensor head of the comparative example, The light-shielding property is slow and the position detection accuracy is poor.

[0012]

According to the optical fiber terminal unit of the present invention, the directivity is excellent, the light-shielding characteristic of the object to be detected is steep, and the position detection accuracy is high.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical fiber terminal unit according to an embodiment of the present invention.

FIG. 2 is a diagram showing light blocking characteristics of an example according to the invention and a comparative example.

[Explanation of symbols]

 1 Optical fiber for light transmission 2 Optical fiber for light reception 3 Holder part 4 Reflective surface 5 Window for light transmission 6 Window for light reception 7 Pinhole

Claims (1)

[Claims] 1. An optical fiber terminal unit which is attached to an end portion of an optical fiber and which emits illumination light from an optical fiber for light transmission and makes transmitted light enter an optical fiber for light reception, wherein the light for light transmission and the light for light reception are provided. It is equipped with a reflecting surface facing the end face and window of the fiber and a holder part for holding the end portion and reflecting surface of each optical fiber inside, and a pin hole is provided in the light receiving and transmitting window. Acts as a diaphragm for adjusting the cross sections of incident light and emitted light.