JP2007179823A - Line illuminator and line illumination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonconventional new line illuminator. <P>SOLUTION: The illuminator for generating linear illumination light includes: a single light source 1; one or more coaxial lens(es) 2; and a cylindrical lens array 3 formed by arranging a plurality of cylindrical lenses 3-i; and is structured such that divergent luminous flux from the single light source 1 is focused on one or more line images LI by the one or more coaxial lens(es) 2 and the cylindrical lens array 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a line illumination device and a line illumination method.

Line-shaped illumination light is widely used for measuring dimensions of an object, inspecting an object surface for scratches, identifying the color of an object, inspecting an object for defects, or scanning light for a scanner.
In order to realize line-shaped illumination light, conventionally, there is known a method of “arranging a plurality of inexpensive light sources such as LEDs” on a line. ”Degrades the intensity distribution (shading) of the line-shaped illumination light, so it is necessary to select a micro light source with uniform light emission intensity, and the selection of the micro light source is troublesome.

  Moreover, as a method of realizing line-shaped illumination light using a single light source, the light from the light source is passed through the optical fiber bundle, the light emission end side of the optical fiber bundle is closely arranged in a line shape, Patent Document 1 discloses a method of forming light in a line shape using light emitted from an optical fiber bundle using a cylindrical lens or a sawtooth condenser lens.

JP-A-6-230227

  This invention makes it a subject to implement | achieve the novel line illumination apparatus and line illumination method which are not in the past.

  The line illumination device according to the present invention is a “device for generating line-shaped illumination light”, and includes a single light source, one or more coaxial lenses, and a cylindrical lens array.

A “single light source” emits a divergent light beam.
Each of the “one or more coaxial lenses” is an optical axis symmetric lens. When there are two or more coaxial lenses, these are arranged on the same optical axis.
The “cylindrical lens array” is formed by arraying a plurality of cylindrical lenses.

A light beam emitted from a single light source is “formed into one or more line images” by one or more coaxial lenses and a cylindrical lens array.
The “line image” is an image that becomes “line-shaped illumination light”.

The “individual cylindrical lens of the cylindrical lens array” of the line illumination device according to claim 1 preferably has a non-arc shape (profile shape in a cross section including an aspherical optical axis) in the power direction. 2).
The “power direction” is the maximum power direction of the cylindrical lens surface, that is, the direction having the maximum curvature, and is the direction orthogonal to the generatrix of the cylindrical lens surface and the optical axis.

  The line illumination device according to claim 1 or 2, wherein the one or more coaxial lenses preferably include one or more aspheric surfaces (claim 3).

  In the line illumination device according to any one of claims 1 to 3, it is preferable to arrange one or more coaxial lenses on the light source side and a cylindrical lens array on the image side (claim 4). However, the cylindrical lens array may be arranged on the light source side, and when there are a plurality of coaxial lenses, the cylindrical lens arrays may be positioned between the coaxial lenses.

  The line illuminating device according to any one of claims 1 to 4, wherein the cylindrical lens array has a "configuration in which the cylindrical lenses are arranged in a line in the power direction", and the light beam from the light source is single. A line image can be formed (claim 5).

  In the line illumination device according to any one of claims 1 to 4, the cylindrical lens array may have a plurality of array regions, and the arrangement direction of the cylindrical lenses may be different for each array region. Item 6). In this case, the light flux from the light source can be formed into a line image for each array region, and “a plurality of line images having different directions” can be obtained.

  Although there is no restriction | limiting in particular in the "single light source" in the line illuminating device of any one of the said Claims 1-6, it is cheap, it is easy to handle, and the change of emitted light intensity is also easy, and it is substantially An LD or LED, or an output end face of a single optical fiber (one optical fiber) (an end face from which light propagating through the optical fiber is emitted) is preferable. The light emitted from the output end face of the single optical fiber may be the light propagated from the LD or LED. In this case, the light synthesized from two or more LDs or two or more LEDs as a single light beam. But you can.

  The line illumination method according to the present invention is an illumination method using the line illumination device according to any one of claims 1 to 7 (claim 8).

  Some supplementary explanation. For the sake of concreteness of explanation, the case of claim 5, that is, the case where the cylindrical lens array is of “a configuration in which the cylindrical lenses are arranged in a line in the power direction” is taken as an example. When the number of cylindrical lenses constituting the cylindrical lens array is n, these n cylindrical lenses are arranged closely in the power direction perpendicular to the bus and the optical axis, with the buses in parallel.

  In this case, an optical system including one or more coaxial lenses and a cylindrical lens array constitutes a separate imaging optical system for each “combination of one or more coaxial lenses and individual cylindrical lenses”. That is, n sets of separate image-forming optical systems are configured by a combination of one or more coaxial lenses and individual cylindrical lenses.

  Since the cylindrical lens has no power in the generatrix direction, the light beam emitted from a single light source is condensed by only one or more coaxial lenses in the “cylindrical lens generatrix direction” in the cylindrical lens array. .

  On the other hand, in the power direction orthogonal to the generatrix and the optical axis of the cylindrical lens, an individual imaging action by the combination of one or more coaxial lenses and individual cylindrical lenses acts. This “one or more coaxial lenses” And “individual image forming action between the individual cylindrical lenses” are set so that the light beam from the light source “extends in the power direction of the cylindrical lens long”. Then, due to the individual imaging action of the one or more coaxial lenses and the individual cylindrical lenses, the light flux from the light source is imaged as “a linear image long in the power direction of the cylindrical lens” according to the individual cylindrical lenses. Will do.

  In this way, the “line images” are formed according to the individual cylindrical lenses, so that “n line images” are formed. These n “line images” are in the length direction. In FIG. 4, the image forming action is set so that “n line-shaped images” overlap each other in the length direction. In this way, “n line-shaped images” are superimposed on each other in the length direction to form a “line image”.

  A light beam emitted from a single light source is divergent, and its intensity varies depending on the “angle from the light beam optical axis”. It is the light beam portion whose angle from the light beam optical axis is “within a certain range” that is involved in the image formation of each cylindrical lens, and the light intensity of this portion differs for each light beam portion, and one light beam Different in the part.

  Accordingly, the “line-shaped image” in which one cylindrical lens is involved in image formation not only differs in intensity but also generally changes in light intensity in the line length direction. However, when these n “line-shaped images” are superimposed on each other in the longitudinal direction, the “non-uniformity of light intensity in each line-shaped image” is averaged as a whole. A “line image” obtained by superposition becomes a linear image having a uniform intensity in the longitudinal direction. This point will be described with reference to a specific embodiment.

  According to the present invention, a novel line illumination device and line illumination method can be realized. Since the line illumination device of the present invention uses a single light source, unlike the method of arranging a plurality of LEDs and the like, there is no trouble of “selecting a micro light source with uniform emission intensity”.

  In addition, since it can be configured with a single light source, one or more coaxial lenses, and a cylindrical lens array, the configuration is simple and easy to assemble, and the number of components is relatively small, so it can be realized at low cost and includes moving parts. There is no reliability in the environment.

Hereinafter, embodiments will be described.
FIG. 1 is a diagram for explaining one embodiment of a line illumination device.
In the figure, reference numeral 1 denotes a light source, reference numeral 2 denotes a coaxial lens, and reference numeral 3 denotes a cylindrical lens array. As shown in the figure, the Z direction is defined parallel to the optical axis direction of the coaxial lens 2, and the three orthogonal directions are defined with the vertical direction in FIG. 1A as the X direction and the vertical direction in FIG. 1B as the Y direction. To do.
The light source 1 is a single optical fiber, that is, an output end face of one optical fiber.

  In FIG. 1A, the X direction, which is the vertical direction, indicates the arrangement direction of the cylindrical lenses 3-1, 3-2,... 3-i,. 1 (b) shows a state in the Y direction parallel to the generatrix direction of the cylindrical lens.

  Since each cylindrical lens 3-i (i = 1, 2,...) Constituting the cylindrical lens 3 does not have power in the direction of the generatrix, as shown in FIG. In the Y direction, the luminous flux is imaged at the imaging position P by “imaging action of only the coaxial lens 2”.

  On the other hand, in the X direction, which is the arrangement direction of the cylindrical lenses 3-i, the light beam from the light source 1 is converted into a condensed light beam by the coaxial lens 2 and is incident on the cylindrical lens array 3, but is incident on the cylindrical lens 3-i. The incident light beam part is subjected to the optical action of the coaxial lens 2 and the optical action of the cylindrical lens 3-i, and the “light beam cross section” is extended in the X direction of FIG. Then, an image is formed as a line image LI long in the X direction at the image forming position P in the Y direction. The line image LI is obtained by superimposing the above-described “line-shaped image” by the imaging action of the coaxial lens 2 and the individual cylindrical lenses 3-i.

The line image LI obtained in this way has a “light intensity distribution in the image length direction (X direction)” that is nearly uniform. The effect of this uniform light intensity will be described with reference to FIG.
2A and 2B show two typical examples of the light intensity distribution when the light passes through the coaxial lens 2 and enters the cylindrical lens array 3. FIG. 2A shows a simple mountain distribution, and this type of distribution is hereinafter referred to as a “convex type”. FIG. 2B shows a two-peak distribution, and this type of distribution is hereinafter referred to as a “concave type”.

As shown in FIG. 2 (a), when a light beam having a convex distribution is incident on the cylindrical lens array, the cylindrical lens 3-i is individually affected by the cylindrical lens 3-i (i = 1, 2,... ·) Extends the incident light beam portion in the X direction (left and right direction in the figure) to form line-shaped images L11, ··· L1i, ···. Although only two line images L11 and L1i are shown in FIG. 2A, a “line image” is formed for each cylindrical lens 3-i.
In the middle part of FIG. 2A, what is indicated by a symbol L1i (i = 1, 2,...) Is a light intensity distribution of the line-shaped image L1i, and the vertical direction corresponds to the light intensity.

  These line-shaped images L1i (i = 1, 2,...) Overlap each other to form the line image LI shown in FIG. At this time, the light intensity of each line-shaped image L1i (i = 1, 2,...) Is not uniform in the image longitudinal direction (X direction), but the convex distribution is “a distribution that is symmetric in the X direction”. Therefore, there is an image in which the light intensity distribution in the longitudinal direction is reversed with respect to the line-shaped image L1i. Therefore, the line image formed by superimposing all the line-shaped images L1i. The light intensity distribution of LI is made uniform in the longitudinal direction (X direction) as shown in the lowermost part of FIG.

As shown in FIG. 2 (b), when a light beam having a concave distribution is incident on the cylindrical lens array, the cylindrical lens 3-i is individually affected by the cylindrical lens 3-i (i = 1, 2,...). ) Stretches the incident light beam portion in the X direction (left-right direction in the figure) to form line-shaped images L21,... L2i,. Although only two line images L11 and L1i are illustrated in FIG. 2A, a line image is formed for each cylindrical lens 3-i.
In the middle part of FIG. 2, a symbol L2i (i = 1, 2,...) Indicates a light intensity distribution of the line-shaped image L2i, and the vertical direction corresponds to the light intensity.

  These line-shaped images L2i (i = 1, 2,...) Are superimposed on each other to form a line image LI shown in FIG. At this time, the light intensity of each line-shaped image L2i (i = 1, 2,...) Is not uniform in the longitudinal direction of the image (X direction), but the concave distribution is “a distribution that is symmetric in the X direction”. Therefore, there exists an image having a light intensity distribution in the longitudinal direction opposite to the image L2i having a line shape. Therefore, the line image LI formed by superimposing all the line-shaped images L2i. The light intensity distribution is made uniform in the longitudinal direction as shown in the lowermost part of FIG.

  The above explanation is for the case where the light intensity distribution in the X direction of the light beam incident on the cylindrical lens array has a symmetric shape in the X direction, but the light intensity distribution is not an arbitrary one having such symmetry. In the case of distribution, the number of cylindrical lenses constituting the cylindrical lens array is increased so that the light intensity in the X direction of the light beam incident on each cylindrical lens is substantially constant in each cylindrical lens.

  In this case, the “line-shaped images by the respective cylindrical lenses” have different light intensities, but the light intensity is substantially constant in the X direction inside each image. Therefore, by superimposing these, a “line image LI having a uniform light intensity in the longitudinal direction” can be realized regardless of the distribution of the incident light beam to the cylindrical lens array in the X direction.

Hereinafter, specific simulation results are shown as examples.
In the embodiment shown in FIG. 1, a case where a “single optical fiber output end face” is used as the light source 1 and a line image having a length of 800 mm and a width of 3.5 mm is formed at a position 1 m away from the light source 1. Assumed.

Example 1
The coaxial lens 2 was a plano-convex lens, and the convex surface was directed to the light source side.
The convex surface of the coaxial lens 2 was a spherical surface having a curvature radius of 64.18677 mm. The lens thickness is 10 mm. The lens diameter is 60 mm.
The cylindrical lens array 3 has a configuration in which six “plano-convex cylindrical lenses” are arranged in the X direction, and the convex surface faces the light source side.

The convex surface of each cylindrical lens has a curvature radius in the X direction of 13.0 mm and a lens thickness of 13 mm. The width per cylindrical lens is 10 mm and the length is 60 mm, and the size of the cylindrical lens array 3 is 60 mm × 60 mm.
The materials of both the coaxial lens 2 and the cylindrical lens array 3 are “ZEONEX 330r (trade name)” of ZEON Corporation.

  The coaxial lens 2 and the cylindrical lens array 3 are arranged such that the distance between the light source (the output end face of the optical fiber) of the light source 1 and the line image LI is 1 mm, the length of the line image LI is 800 mm, and the width is 3. The positional relationship between the coaxial lens 2 and the cylindrical lens array 3 was optimized so as to be 5 mm.

  As the angular distribution of the emission intensity in the X direction at the “output end face of the single optical fiber” that is the light source 1, “concave distribution” shown in FIG. 3A and “convex distribution” shown in FIG. "It was set.

  In Example 1, for the concave distribution, the light intensity distribution of the line image LI was examined by simulation. FIG. 4 shows the result. The light intensity distribution of the formed line image LI is as shown in FIG. 4A in the longitudinal direction (X direction) and as shown in FIG. 4B in the width direction (Y direction). The light intensity on the vertical axis is a value obtained by standardizing the maximum intensity to 1.

  From the result of FIG. 4, a “line image having a light intensity of approximately constant (0.8 to 1.0) over a length of 800 mm and a light intensity of 0.3 or more within a width of 3.5 mm” is obtained. It can be seen that an image is formed.

Example 2
In Example 1, the convex surface of the coaxial lens 2 was aspherical, and each cylindrical lens surface of the cylindrical lens array was a non-arc shape.
The shape of the aspherical surface or noncircular arc was a known aspherical shape (noncircular arc shape) using a conic constant: k and a “fourth-order aspheric coefficient”: A.

  The coaxial lens 2 has a paraxial radius of curvature: 64.18677 mm, a conic constant: k = −0.67457, and an aspheric coefficient: A = −0.67425. The lens thickness is 10 mm. The lens surface of the cylindrical lens 3-i has a paraxial radius of curvature of 13.0 mm and a conic constant of k = -1. The lens thickness is 10 mm.

  At this time, the light intensity distribution of the line image LI with respect to the [concave distribution] shown in FIG. 3A is shown in FIG. 5A for the longitudinal direction (X direction) and FIG. 5B for the width direction (Y direction). As shown in Further, the light intensity distribution of the line image LI with respect to the “convex distribution” as shown in FIG. 3B is shown in FIG. 6A for the longitudinal direction (X direction) and FIG. 6B for the width direction (Y direction). ).

  5 and 6, it can be seen that in Example 2, a “good line image” having extremely high uniformity over the longitudinal direction of 800 mm and sufficiently condensed in the width direction can be obtained. Comparing the results of FIGS. 5 and 6 with the results of FIG. 4, the effect of adopting an aspherical surface for the lens surface of the coaxial lens and an aspherical shape for the cylindrical lens is clearly understood.

  In Example 1, when only the convex surface of the coaxial lens 2 is aspherical as in Example 2, the light intensity distribution of the line image LI is the distribution of incident light flux in the longitudinal direction (X direction). 4 is a concave shape, the light intensity distribution in the width direction (Y direction) is as shown in FIG. 5B. That is, the “distribution in the X direction” of the light intensity of the line image LI is influenced by the lens surface shape of the cylindrical lens, and the “distribution in the Y direction” is affected by the lens surface shape of the coaxial lens 2. Independent of each other.

  5 and FIG. 6, there is a difference between the “angle distribution of the light intensity in the light source” between the concave and convex types. The light intensity distribution is the same in both directions.

  That is, when the lens surface of the coaxial lens is aspherical and the lens surface of the cylindrical lens is aspherical, a good line image can be obtained regardless of the angular distribution of the light intensity at the light source.

  The line illuminating device described in the embodiment and the example 1 thereof are devices that generate line-shaped illumination light, and include a single light source 1 that emits a divergent light beam, a coaxial lens 2, and the like. A cylindrical lens array 3 in which a plurality of cylindrical lenses 3-i (i = 1, 2,...) Are arrayed, and a single lens is formed by one or more coaxial lenses 2 and the cylindrical lens array 3. A line illumination device that forms a divergent light beam from a light source 1 on a line image LI (Claim 1).

  In the second embodiment, each cylindrical lens 3-i (i = 1, 2,...) Of the cylindrical lens array 3 has a non-arc shape in the power direction (X direction) that is the lens arrangement direction (claimed). Item 2), the lens surface on the light source side of the coaxial lens 2 has an aspherical shape (Claim 3). In each of Examples 1 and 2, the coaxial lens 2 is disposed on the light source 1 side, and the cylindrical lens array 3 is disposed on the image LI side.

  Further, the cylindrical lens array 3 is configured by arranging the cylindrical lenses 3-i (i = 1, 2,...) In a line in the power direction (X direction), and the light beam from the light source 1 is a single line image. An image is formed on the LI (Claim 5). The single light source 1 is an “output end face of a single optical fiber”.

  Therefore, the line illumination method (claim 8) with a good line image can be implemented by using the line illumination device of the above embodiment and Examples 1 and 2.

  The case where the cylindrical lens in the cylindrical lens array is a “convex cylindrical surface having power in the X direction” has been described above, but various forms of cylindrical lens surfaces are allowed. To give some examples, as shown in FIG. 7A, a cylindrical lens array 71 using a concave cylindrical lens, a cylindrical lens array 72 combining a convex cylindrical lens and a concave cylindrical lens, and the like are possible.

  In addition, as shown in FIG. 7C, the cylindrical lens array is provided with two array regions, and “two types of cylindrical lenses 71A and 71B whose buses face in directions perpendicular to each other” are arranged in each array region. (Claim 6). In this case, line images orthogonal to each other can be formed. In this way, by arranging a plurality of types of cylindrical lens surfaces having different generatrix directions, a line image such as “L”, “L”, “*” can be generated as illumination light.

It is a figure for demonstrating one Embodiment of a line illuminating device. It is a figure for demonstrating the principle by which the light intensity distribution of a line image is equalized in a longitudinal direction. It is a figure which shows two examples of angle distribution of light intensity of the light source in connection with an Example. 6 is a diagram illustrating a light intensity distribution of a line image in Example 1. FIG. FIG. 10 is a diagram showing a light intensity distribution of a line image in Example 2. FIG. 10 is a diagram showing a light intensity distribution of a line image in Example 2. It is a figure which shows the modification of a cylindrical lens array.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Coaxial lens 3 Cylindrical lens array LI Line image P Image formation position

Claims (8)

An apparatus for generating line-shaped illumination light,
A single light source that emits a divergent light beam;
One or more coaxial lenses;
A cylindrical lens array formed by arraying a plurality of cylindrical lenses;
A line illumination device, wherein the divergent light beam from the single light source is formed into one or more line images by the one or more coaxial lenses and a cylindrical lens array. The line lighting device according to claim 1, wherein
A line illumination device characterized in that each cylindrical lens of the cylindrical lens array has a non-arc shape in the power direction. The line illumination device according to claim 1 or 2,
A line illumination device, wherein one or more lens surfaces of one or more coaxial lenses are aspherical. In the line lighting device according to any one of claims 1 to 3,
One or more coaxial lenses are arranged on the light source side, and a cylindrical lens array is arranged on the image side. In the line lighting device according to any one of claims 1 to 4,
A line illumination device, wherein the cylindrical lens array includes cylindrical lenses arranged in a line in a power direction, and forms a light beam from a light source into a single line image. In the line lighting device according to any one of claims 1 to 4,
A line illumination device, wherein the cylindrical lens array has a plurality of array regions, and the array direction of the cylindrical lenses is different for each array region. In the line lighting device according to any one of claims 1 to 6,
A line illumination device, wherein the single light source is an output end face of an LD or LED or a single optical fiber.   A line illumination method using the line illumination device according to any one of claims 1 to 7.

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