JPH01235808A - Optical fiber sensor for detecting position - Google Patents

Abstract

PURPOSE:To improve incident efficiency by diagonally cutting the end faces of optical fibers in such a manner that the incident light parallels the wall surfaces of the optical fibers when the light of an imaging spot enters the end faces of the optical fiber at the angle defined by Scheimpflug condition. CONSTITUTION:The end faces of the optical fibers 3a are diagonally cut at the prescribed angle in such a manner that the incident light parallels with the wall surface 5 of the optical fibers 3a when the light of the imaging spot S enters the end faces of the optical fibers 3a at the angle defined by the Scheimpflug condition, by which an imaging plane 4 is formed. Photodetectors 3b constituting an array sensor are provided on the other end faces of the optical fibers 3a. A detection processing part 3c is so constituted that the position detecting data are computed and outputted in accordance with the outputs of the respective photodetectors 3b. The optical fiber sensor 3 constituted in such a manner constitutes a flat surface where the end faces of the optical fibers 3a have the angle epsilon. Since the polishing of the end faces is easy, the incident efficiency to the optical fibers 3a is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an optical fiber sensor used in a triangulation type position detector.

[Conventional i-technique 1] In general, a triangulation type position detector irradiates a detection target X with a light beam P emitted from a laser 1 and sends the reflected lights Ra and Rb to a lens 2, as shown in Figure tjS3. The light is focused and imaged on one end surface of the optical fiber of the optical fiber sensor 3 for position detection, and changes in the amount of light are detected by an array sensor consisting of 7 photodetectors arranged on the other end surface of the 7 optical fibers. Based on this, the position of the imaging spot is detected and phase separation information up to the detection target X is obtained.

Conventionally, the optical fiber section of the optical fiber sensor 3 for position detection used in the above-mentioned position detector has a large number of optical fibers 3a arranged in a line in the moving direction of the imaging lens (S), as shown in FIG. It was formed as follows. By the way, in order to form an image in a focused state on the imaging plane (the end face of the optical fibers arranged in a row) of the optical fiber sensor 3, the fifth
It was necessary to form the imaging plane 4 so as to satisfy the Scheimpflug condition as shown in the figure. In the figure, L is the separation between the light emitting system and the light receiving system, P is the light beam, Ra, Rb is Q,
a, (reflected light from the detection target , '.In the conventional example, as shown in FIG. The Scheimpflug condition is commonly used in the field of photogrammetry (for example, in the photogrammetry method (Kyoritsu Shuppan, 1977, P1).
24)) has been done.

[Problem to be solved by the invention 1 However, in the above-mentioned conventional example, the optical fiber 3
Since the image forming surface 4 was formed by arranging the end surfaces of the fibers in stages, it was difficult to measure the end surfaces of the fibers, resulting in poor incidence efficiency into the optical fiber 3a. There is a problem that the positional accuracy deteriorates and the image forming area S becomes blurred, and there is also a problem that a shadow of the adjacent light beam 7T 3a occurs, increasing light loss due to the unevenness of the image forming surface 4. Ta.

The present invention has been made in view of the above points, and its purpose is to improve the efficiency of incidence into an optical fiber.
It is an object of the present invention to provide an optical fiber sensor for position detection in which an imaging spot is not blurred and light loss caused by unevenness of an imaging surface is small.

[Means for Solving the Problems] The optical fiber sensor for position detection of the present invention forms an image based on changes in the amount of light detected by an array sensor in which a plurality of optical fibers are arranged in a line in the moving direction of an imaging spot. This is an optical fiber sensor used in a triangulation type position detector that detects the position of a spot, and when the light of the imaging spot is incident on the end face of the optical fiber at an angle according to the Scheimpflug condition, the incident light is The end face of the optical fiber is cut obliquely at a predetermined angle so that the optical fiber is refracted and incident parallel to the wall surface of the optical fiber.

[Function] The present invention is configured as described above, and when the light of the imaging spot is incident on the end face of the optical fiber at an angle according to the Scheimpflug condition, the incident light is The fiber is cut diagonally at a predetermined angle so that it is refracted and incident parallel to the wall surface of the fiber.
The 7-eye fiber end face of the optical 7-eye light is a flat surface, which makes it easy to polish the end face, resulting in good incidence efficiency into the fiber.Moreover, the fiber end face is a flat face that satisfies the Scheimprug condition. Therefore, the image forming spot power does not become blurred, and furthermore, unlike the conventional example, it is possible to reduce optical loss caused by unevenness of the image forming surface.

[Embodiment] Fig. 1 and Fig. 2 show an embodiment of the present invention, in which light from an imaging sub-box) S is illuminated by a light beam sensor 31 similar to the conventional example described above. angle a according to the
When light 7 is incident on the end face of 3a, the incident light becomes light 7
The light 7 eyeper end face 3a is obliquely cuffed at a predetermined angle ε (the angle with respect to the plane orthogonal to the optical axis of the light 7 eye t<3a) so that the light 7 is refracted and incident parallel to the wall surface 5 of the eyeglass 3a. The image forming surface 4 is formed by

Further, the other end surface of the optical 7-eye detector 3a is provided with 7 Oto-detectors 3b constituting an array sensor, and the detection processing section 3b calculates and outputs position detection data based on the output of each of the 7 Oto-detectors 3b. It has become.

Hereinafter, the design of the optical fiber sensor 3 of the example will be explained. Now, reflected light R enters as shown in Figure 2,
The angle ε at which the incident light R′ into the optical fiber 3a is incident parallel to the wall surface 5 is determined by the Scheimpflug condition tan(r = M tan β (1) where M satisfies the coupling magnification. However, when the diameter of the optical fiber is φ, the diameter of the end face of the optical fiber 3a is Z, and the refractive index of the optical fiber 3a is n, the following equation must be satisfied.

e09ε=φ/Z・・・・・・・・・・・・(2) si
n(1/3!nε=n......(3) Also, from Figure 2, 5in(r/2-a)=cosa=Yl/Z--(4)
Also, from Figure 5, Y+=MxY, ・・・・・・・・・・・・・・・・・・
...(5) Y, =Acosβ...
・・・・・・・・・・・・(6) However, A is the required displacement resolution of one optical fiber. Next, determine β, φ, and A, and solve equations (1) to (6) α
= arctan(M X tanβ)ε=BHin(
sinα/n) However, a= (n2-1)A 2sin2βb-n2
A 2cos"β c=n"φ is obtained.

As described above, the design data M1 of the optical fiber sensor 3 is
α and C are determined, and an optical fiber sensor 3 as shown in FIG. 1 is obtained. Note that the resolution of one optical fiber 3a can be compressed from φ in the conventional example to Y (=MA sin β).

In the optical fiber sensor 3 formed in this way, the fiber end face is a flat face with a predetermined angle ε, and the end face can be easily fixed, so that the efficiency of incidence on the optical fiber 3a can be improved. Moreover, since the fiber end face constituting the imaging surface 4 is a flat surface that satisfies the Scheimpflug condition, the imaging spot S will not become blurred, and furthermore, unlike the conventional example, the imaging spot S will not be blurred due to unevenness of the imaging surface 4. This makes it possible to reduce optical loss.

〔Effect of the invention〕

The present invention is configured as described above, and when the light of the imaging spot is incident on the end surface of the optical fiber at an angle according to the Scheimpflug condition, the incident light becomes parallel to the wall surface of the optical fiber. The optical fiber is cut diagonally at a predetermined angle so that it is refracted and incident, and the end face of the optical fiber is a flat surface, making it easy to square the end face, improving the efficiency of incidence into the fiber. Moreover, since the fiber end face is a flat surface that satisfies the Scheimpflug condition, the imaging spot does not become blurred, and unlike conventional examples, optical loss due to unevenness of the imaging surface is reduced. It has the effect of being able to

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an embodiment of the present invention, Fig. tjS2 is an explanatory diagram of the same operation as above, and Fig. 3 is an explanation of the operation of a triangulation type distance measuring device in which the optical fiber sensor for position Jl according to the present invention is used. 4 is a side view of the main part of the conventional example, FIG. 5 is an explanatory diagram of the same operation as above, and FIG. 6 is a side view of the main part of another conventional example. 3 is an optical fiber sensor, 3a is a light beam sensor, and 4 is an imaging plane. Agent Patent Attorney Ishi 1) Ai Voluntarily writing amendments to Figure 7 2 procedures) 1. Display of the case 1986 Patent Application No. 61515 2 Name of the invention Optical fiber sensor for position detection 3, person making the correction Relationship to the case Patent applicant address 1048 Kadoma, Kadoma City, Osaka Prefecture Name (58
3) Matsushita Electric Works Co., Ltd. Representative Toshio Miyoshi 4, agent postal code 530 5, date of amendment order [1] Replace “up to
I will correct it to "between". [21 Change “C=n2φ” in the 7th line from the bottom of the 7th ditto to “
I will correct it to "C=n2φ2". [3] 1-MAs on page 7, lines 1 and 2 from the bottom of the same page
1nβ” will be corrected to l”MAcosβ”. [41 Figures 2, 3, and 5 of the attached figures of this application are corrected as shown in the attached sheet. Agent Patent Attorney Ishi 1) Ai Shichimo 2 Figure 3 Figure B' Sha 5 Figure

Claims (1)

[Claims] (1) Light used in a triangulation-type position detector that detects the position of an imaging spot based on changes in light intensity detected by an array sensor with multiple optical fibers arranged in the direction of movement of the imaging spot. The optical fiber sensor is a fiber sensor in which, when the light of the imaged spot is incident on the end face of the optical fiber at an angle according to the Scheimpflug condition, the incident light is refracted so as to be parallel to the wall surface of the optical fiber and then enters the optical fiber. An optical fiber sensor for position detection, whose end face is cut diagonally at a predetermined angle.