JPH109813A - Optical position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of an optical position detector by providing a condensing means and an imaging means constituted of a planar waveguide on a same substrate. SOLUTION: A luminous flux introduced from an input optical fiber 104 to a planar waveguide (condensing means) 103 propagates while being confined in the Y-axis direction and being dispersed in the Z-axis direction depending on the numerical aperture of the fiber. It is reflected on the curved end face 106 of the planar waveguide and delivered from the outgoing end face 107 before being focused at a desired measuring point on a plane 110 to be detected. A luminous flux reflected on the plane 110 to be detected is introduced from an incoming end face 112 to a planar waveguide (focus means) 111. The luminous flux confined in the Y-axis direction is totally reflected inward on the curved end face 113 of the planar waveguide and the image of a spot on the plane 110 to be detected is separated to respective branch waveguides 114a, 114b depending on the focus position and then the separated states are combined through output optical fibers 115a, 115b and taken out externally. Since the light can be condensed and focused without employing any lens, dimensions of the detector can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical position detecting device for detecting a position using a triangulation method.

[0002]

2. Description of the Related Art Conventionally, a method called a triangulation method has been widely used as a position detector, and since it is inexpensive and simple, it is frequently used as an autofocus sensor for a camera. Fig. 4 shows, for example, the publication “Need for optical measurement and seeds”.
FIG. 136 is an explanatory diagram for describing a position detection method by a triangulation method described in P. 167 (edited by the Metrology Association of Japan). As shown in the figure, a light source 1, such as a laser, an imaging lens 2, a position detection element ｛PSD (Pos
The imaging system is configured to be tilted obliquely with respect to the displacement direction of the detection target surface 4 or to tilt the light incident direction using｝ 3 or the like. When the surface 4 to be detected is displaced from the reference position, the spot on the surface 4 to be detected changes, and the position of the surface 4 to be detected is calculated using the fact that the image forming position on the position detection element 3 changes accordingly. Is what you do.

[0003]

In the above conventional example, a parallel beam of laser is used and no lens is used on the light projecting side. However, when a compact semiconductor laser is used as a light source, a collimator lens is indispensable. In the case where a gas laser is used, a lens system is unnecessary, but the laser size is essentially large. That is, in the position detector using the conventional triangulation method, since a lens having a general three-dimensional curvature distribution is used for condensing light and forming an image, there is a limit in reducing the size of the detection device. .

[0004] The present invention has been made to solve such a problem, and an object of the present invention is to provide an optical position detecting device which can be downsized.

[0005]

A first optical position detecting device according to the present invention is a light condensing means for deflecting light introduced from a light source and condensing the light at a reference position, and detecting the light by the light converging means. Imaging means for imaging reflected light of a spot formed on a surface, and detection for detecting displacement of a detected surface from a reference position from a change in an imaging position of a spot image formed by the imaging means An optical position detecting device, wherein the optical axis of the focusing means and the imaging means are non-coaxial, wherein the focusing means and the imaging means are provided on the same substrate, and The means is constituted by a flat waveguide.

According to a second optical position detecting device of the present invention, in the first optical position detecting device, the light condensing means has an optical means having a uniaxial focusing action on the light exit side of the flat waveguide. Wherein the imaging means comprises optical means having a uniaxial focusing action on the light incident side of the flat waveguide.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an optical position detecting device according to an embodiment of the present invention.
03 and a second flat plate waveguide 111 serving as an imaging means are provided on the same substrate 101, and the optical axes of the condensing means and the imaging means are non-coaxial, so that position detection is possible with a small device. Become.

Next, the operation of the light collecting means will be described.
The first flat waveguide 1 from the input optical fiber 104 from the light source
03, and are confined in the Y-axis direction (perpendicular to the paper surface) as shown by three solid lines indicated by A in the figure, and propagate while diffusing in the Z-axis direction according to the numerical aperture of the fiber. , And enters the first planar waveguide end face 106 having a curved shape. The light reflected on the flat waveguide end face 106 exits from the emission end face 107 of the light from the first flat waveguide 103 and reaches the detection surface 110. Here, the curvature of the flat waveguide end face 106 and the inclination of the curved face are such that the divergent light from the input optical fiber 104 causes total internal reflection and is deflected by a predetermined angle with respect to the Z axis in the XZ plane. Is Z
It is determined to have a focal point at a general center position (reference position) of a desired measurement range of the detection surface 110 while being inclined at a predetermined angle with respect to the axis.

Next, the operation of the imaging means will be described.
The light beam reflected by the surface to be detected 110 is introduced into the second planar waveguide 111 from an incident end surface 112 of the light to the second planar waveguide 111. The luminous flux introduced and confined in the Y-axis direction is converted into a second planar waveguide end face 11 having a curved shape.
3, an image is formed by total internal reflection similarly to the end surface 106 of the first planar waveguide.

Next, the operation of the detecting means will be described.
When the plane to be detected 113 is located at the approximate center position (reference position) of the measurement, the image of the spot on the surface to be detected 110 is converted into the second plane waveguide 111 by the inclination and the curvature of the plane waveguide end face 113. Waveguides 114a and 1
It is set so that an image is formed at the branch point 14b. The luminous flux in the second flat waveguide 111 is separated into each branch waveguide at the branch point according to the image forming position,
The separated state is detected, and the separated state is coupled to the output optical fibers 115a and 115b and taken out.

FIG. 1 shows a case where the optical axis of the light collecting means is inclined with respect to the direction of displacement of the surface to be detected. However, the present invention is not limited to this. The system may be such that the optical axis of the imaging means is inclined with respect to the Z axis so as to coincide with the Z axis, and the optical axes of the focusing means and the imaging means may be non-coaxial.

FIG. 2 is a block diagram of an optical position detecting apparatus according to an embodiment of the present invention. In the optical position detecting apparatus shown in FIG. 1, a rod-shaped lens 108 is used as an optical means having a uniaxial focusing function. is there. A cylindrical lens is also used in the same manner as the rod lens. By providing the rod-shaped lens 108 on the light emission side of the first flat waveguide 103, the amount of spots focused on the detection surface 110 is increased, the SN ratio is improved, and the light of the second flat waveguide 111 is reduced. By providing the light on the incident side, light from the surface to be detected can be efficiently formed on the waveguide, so that the amount of light for image formation is increased and the SN ratio is improved. As a result, the SN ratio for position detection is improved.

[0013]

【Example】

Embodiment 1 FIG. FIG. 1 is a configuration diagram of an optical position detecting device according to a first embodiment of the present invention. In the figure, 101 is a substrate, 1
02 is a buffer layer, 103 is a first planar waveguide, 104
Is an input optical fiber, and 105 is an optical fiber holder.
Reference numeral 106 denotes an end surface of the first flat waveguide having a curved surface shape. The curvature and the inclination of the curved surface are such that the formed convergent light beam has a focus at the general center position (reference position) of the desired measurement range of the detection surface. Has been determined. Reference numeral 107 denotes an emission end face of light from the first flat waveguide, 110 denotes a detection surface, 111 denotes a second flat waveguide, and 112 denotes an incident end face of light to the second flat waveguide. Reference numerals 114a and 114b denote wedge-shaped branch waveguides that continue from the second planar waveguide 111, and 115a and 115b denote output optical fibers. Reference numeral 113 denotes an end face of the second flat waveguide having a curved surface shape, and its inclination and curvature are such that when the detection target surface 110 is located at the center position of the measurement, the spot image on the detection target surface 110 is It is set so that an image is formed at the branch point between the branch waveguides 114a and 114b.

The buffer layer 102 is formed on the substrate 101 by adding optical fibers 104, 115a and 1
It is formed so as to approximately match the cladding thickness of 15b,
The optical fiber holder 105 is provided with the optical fiber 1.
Each position and size are determined so as to guide 04, 115a and 115b to a predetermined position on the substrate.

The output optical fibers 115a and 115
In order to efficiently couple the light beam to the b, it is better that the shape of the end of the branch waveguide and the shape of the core of the output optical fiber are closer, and the thickness of the second planar waveguide is set so as to roughly match this. And controlling the width at the end of the branch waveguide,
Further, the optical fiber holder 105 is arranged so that the core position of each output optical fiber coincides with the terminal position of the branch waveguide.

Next, a method of manufacturing the optical position detecting device according to the embodiment of the present invention will be described. Hereinafter, an optical position detecting device according to an embodiment of the present invention will be described based on a case where the optical position detecting device is manufactured by a technique using lithography used for manufacturing a semiconductor, but the present invention is not limited to this.

The constituent material of the optical position detecting device of the present invention may be any material as long as it is transparent at least at the wavelength of the light wave used by the waveguide. When such materials are used, various kinds of materials such as SiO ₂ , optical glass and optical polymer are used, and other materials are more various, but one example will be specifically described below. That is, for example, using glass as the substrate, applying a photoresist with a spinner or the like, patterning the buffer layer and the two-dimensional shape of the optical fiber holder by photolithography, and sputtering the glass to the same thickness as the clad thickness of the optical fiber by sputtering or the like. After lamination, the buffer layer and the optical fiber holder are formed by lift-off, etching, or the like. At this time, the glass may not be related to the glass of the substrate, and it is also possible to form the substrate glass by etching. Next, a waveguide is formed by a similar lithography process. It is desirable that the waveguide thickness is equal to the core diameter of the optical fiber from the viewpoint of light utilization efficiency,
Further, in order to confine light in the waveguide, the refractive index of the waveguide material must be sufficiently higher than the refractive index of the buffer layer. Thereafter, the optical fiber is fitted into the holder, and if necessary, bonded. By using the semiconductor technology as described above, the optical position detecting device according to the embodiment of the present invention can be manufactured with high productivity.

Next, an example of a method for detecting the displacement of the detected surface from the reference position from the change of the image forming position of the spot image by the detecting means will be described in detail. When the surface to be detected 110 is at the center position of the measurement, the second planar waveguide end surface 11
In the configuration 3, the spot image is formed at the branch position of the branch waveguides 114a and 114b, and an equal amount of light is extracted to each output optical fiber. When the detected surface approaches the position detection device, the spot position moves in the −X direction because the light beam emitted from the first flat plate waveguide 103 is inclined in the XZ plane with respect to the Z axis. The detected surface 11 at this time
The reflected light from 0 forms an image at the branch position as a light ray such as a one-dot chain line in FIG. 1, and the image forming point is displaced in the −Z direction. For this reason, the amount of light incident on the branch waveguide is small in the + Z side branch waveguide 114a and is large in the -Z side branch waveguide 114b. As a result, the amount of light emitted from the output fiber also changes. Become.
On the other hand, when the surface to be detected has moved away from the position detecting device, the image forming point is +
As a result, the amount of light extracted from the output optical fiber 115a increases, and the amount of light extracted from the output optical fiber 115b decreases.

The output optical fibers 115a and 115
FIG. 3 shows the correlation between the amount of light output from b and the position of the detected surface. In the figure, 201 is the output optical fiber 115
The output 202a is the output of the output optical fiber 115b, the vertical axis is the output, and the horizontal axis is the position. In the figure, P is a reference position, and a region where the detected surface is closer to the position detecting device than the reference position. Is shown as near, and the far area is shown as far. As is apparent from FIG. 3, when the detected surface 110 is at the reference position P, an equal amount of light is extracted by each output optical fiber, and the output of each output optical fiber causes the detected surface to be displaced from the reference position P. Can be detected.

Embodiment 2 FIG. FIG. 2 is a configuration diagram of an optical position detecting device according to a second embodiment of the present invention. In the figure, 10
Reference numeral 8 denotes a rod-shaped lens which is used as optical means having a uniaxial convergence action. Reference numeral 109 denotes the rod-shaped lens holder,
The position and size are determined so as to guide the rod-shaped lens 108 to a predetermined position on the substrate. That is, except that the rod-shaped lens 8 is provided as shown in FIG. 2, the configuration is the same as that of the optical position detecting device of the first embodiment shown in FIG. 1, and it can be manufactured in the same manner as the first embodiment.

Next, the operation will be described. The light reflected on the first flat waveguide end face 106 exits from the light output end face 107 of the light from the flat waveguide, and reaches the detection surface 110 via the rod-shaped lens 108. Here, the curvatures of the first planar waveguide end face 106 and the rod-shaped lens 108 are such that the convergent light flux formed by each has a focus at the general center position (reference position) of the desired measurement range of the detection surface 110. Is determined. The light beam reflected by the detection surface 110 is reflected by the rod-shaped lens 1
08 again, the light is incident on the second flat waveguide 111 from the incident end face 112 of the light to the second flat waveguide 111,
An image is formed at the branch point of the branch waveguides 114a and 114b as in the first embodiment. Here, the second planar waveguide end face 1
The positions of the rod 13 and the rod lens 108 are determined such that the second flat waveguide end face 113 is located at the focal position of the reflected light from the detection surface 110 converged in the Y-axis direction by the rod lens 108.

As shown in FIG.
The amount of spots focused on the surface to be detected is increased by providing the light exit side of the plate waveguide 107 of
Since the light from the surface to be detected can be efficiently formed on the waveguide by providing the light on the light incident side of the second flat waveguide 111, the light quantity of the image is increased and the S / N ratio is improved. Is improved.

In this embodiment, the case where the rod-shaped lens 108 is provided on the same substrate 101 as the first flat waveguide 103 and the second flat waveguide 111 is shown, but the present invention is not limited to this. That is, light emitted from the first flat waveguide 103 enters the rod-shaped lens 108 and reaches the detection surface 110, and light reflected by the detection surface 110 re-enters the rod-shaped lens 108, and What is necessary is just to inject into the wave path 111.

[0024]

According to the first optical position detecting device of the present invention, the light condensing means for deflecting the light introduced from the light source and condensing the light at the reference position, and the light converging means on the surface to be detected by this light condensing means Image forming means for forming an image of reflected light of the formed spot, and detecting means for detecting a displacement of the detected surface from a reference position from a change in the image forming position of the spot image formed by the image forming means. An optical position detecting device in which the optical axis of the light focusing means and the image forming means is non-coaxial, wherein the light focusing means and the image forming means are provided on the same substrate, and the light focusing means and the image forming means are flat It is composed of a waveguide and has an effect that downsizing is possible.

According to the second optical position detecting device of the present invention, in the first optical position detecting device, the light condensing means has an optical axis converging function on the light exit side of the flat waveguide. The imaging means is provided with an optical means having a uniaxial convergence function on the light incident side of the flat waveguide, and has an effect that the SN ratio of detection is large.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical position detection device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical position detection device according to a second embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a correlation between an output of the optical position detecting device according to the embodiment of the present invention and a position of a detected surface.

FIG. 4 is an explanatory diagram for explaining a position detection method using a conventional triangulation method.

[Explanation of symbols]

101 substrate, 103 first planar waveguide, 106 first planar waveguide end face, 108 rod-shaped lens, 110 detected surface, 111 second planar waveguide.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Kazuo Takashima 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (2)

[Claims] 1. A light collecting means for deflecting light introduced from a light source and condensing the light at a reference position, an image forming means for forming an image of reflected light of a spot formed on a surface to be detected by the light condensing means, And a detecting means for detecting a displacement of the detected surface from a reference position from a change in the image forming position of the spot image formed by the image forming means, wherein the optical axis of the light collecting means and the optical axis of the image forming means are non-coaxial. An optical position detecting device, wherein the light-collecting means and the image-forming means are provided on the same substrate, and the light-collecting means and the image-forming means are constituted by a flat waveguide. Detection device. 2. A light collecting means comprising an optical means having a uniaxial focusing function on a light emitting side of a flat waveguide, and an imaging means having an optical focusing means on a light incident side of the flat waveguide. The optical position detecting device according to claim 1, further comprising: