JPH04168309A - Form measuring apparatus by optical cutting method - Google Patents

Abstract

PURPOSE:To secure a required measuring resolution and to obtain an image of a light cutting line magnified in the lateral or longitudinal direction of the viewfield of a camera by using a lens device which forms an image with unequal magnifications in the lateral and longitudinal directions and the projecting side of a curved face of which is directed to an object to be measured. CONSTITUTION:A lens device 5 forms an image with unequal magnifications between the longitudinal and lateral directions. In a frame body of the device 5 detachable to a camera lens 2a, there are fitted sequentially from a lens 2, a group of lenses 5a at the side of the camera lens and a group of lenses 5b at the side of an object to be measured. The principal planes of the two groups of lenses is spaced a distance (d). The group 5a is constituted of a cylindrical double-face convex lens, while the group 5b is comprised of two cylindrical plano-concave lenses. The surface of the same distance from the front and rear surfaces of the cylindrical plano-concave lens is a curved face. The projecting side of the curved face of each plano-concave lens is directed to an object A to be measured while the lens is held in the posture assuming the lens effect in the lateral direction of the viewfield of the camera 2. Accordingly, the required measuring resolution is secured in the longitudinal direction of the viewfield of the camera, and an image of an optical cutting line all over the measuring area can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a shape measuring device that measures the shape of an object using a light cutting method.

[Conventional technology]

As shown in FIG. 4 of the configuration explanatory diagram, a conventional shape measuring device using the optical cutting method includes a slit light source 51 that projects a slit light (striated photon surface) onto the measurement object A, and a slit light source 51 A television camera 52 is disposed at a predetermined position off the optical axis of the camera and captures an image of a light section line (bright line) S generated at a portion where the slit light intersects the measurement target, and a light section line image from the television camera 52. A device is known that includes a signal processing device 53 that processes signals according to a well-known procedure and outputs the result of shape measurement of the object A to be measured. Note that 54 is a monitor television connected to the signal processing device 53 and into which the optical cut line image signal from the television camera 52 is input.

Hereinafter, the measurement of uneven steps on a measurement object as shown in FIG. 4 using the shape measuring device having such a configuration will be described in more detail. The slit light source 51 has a radiation W of 100
The slit light source 51 is disposed directly above the 0 mm measuring object A, and the slit light from this slit light source 51 is projected perpendicularly to the measuring object. In addition, a standard camera with a focal length f = 50 mm is placed at a position where the optical axis forms an angle of θ = 60° with respect to the photon surface by the slit light and the shape of the light cutting line S is viewed from the side diagonally above. A television camera 52 equipped with a lens 52a is arranged in such a manner that the longitudinal and lateral direction of the camera's field of view is the longitudinal direction of a light cutting line S generated on the measurement target A.

In this case, the effective dimensions of a general solid-state image sensor located on the imaging plane of the television camera 52 are 6.6 mm in length and 8.8 m in width.
m, so when the resolution ε of the solid-state image sensor is ε=10 μm and the imaging distance is L, the measurement resolution N is N=(
It is given by ε・L)/(fo・SiB6). Therefore,
If a measurement resolution N of at least 0.5 mm is required, the imaging distance should be (N-fo SiB6)/
Since ε is expressed as L<2.17m, this can be expressed as 2
It is set to m.

When the imaging distance is set to 2 m, the imaging magnification expressed by f, /L becomes 0.025, and the radiation W = 1000 m.
The dimension length on the imaging plane in the width direction of the measurement target A of m is calculated to be 25 mm. However, as described above, the effective dimension in the lateral direction of the solid-state image sensor of the television camera 52 is 8.8 mm. As a result, as shown in FIG. 3, the optical section line image is 1/2 of the entire measurement area.
Only a portion of 8 (=8.8/25) was obtained.

[Problem to be solved by the invention]

In this way, conventional shape measuring devices are equipped with a television camera with a normal camera lens, so depending on the object to be measured, if you try to secure the required measurement resolution, it may be difficult to move in one direction (the example in Figure 4). However, there is a problem in that the camera field of view is insufficient in the lateral direction. For this reason, it is necessary to line up multiple television cameras to obtain the necessary field of view, which poses problems in that measurement takes time and the equipment becomes larger and more complex.

This invention was made in view of the above points, and
A television camera with a camera lens that images the light cutting line,
By installing an imaging lens device with unequal vertical and horizontal magnification that changes the imaging magnification in the vertical and horizontal directions of the camera's field of view, the camera can be adjusted to suit the object to be measured while ensuring the required measurement resolution. The object of the present invention is to provide a shape measuring device using a light section method, which is capable of obtaining a light section line image in a state where the field of view is enlarged in the horizontal or vertical direction.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a slit light source that projects a slit light onto an object to be measured, and a slit light source that is disposed at a predetermined position off the optical axis of the slit light source and intersects the object to be measured by the slit light. A shape measuring device using an optical section method that measures the shape of an object to be measured based on the optical section line image signal from the television camera, which is equipped with a television camera that captures an image of an optical section line formed in a part where the optical section line is formed. Two lens groups arranged with a predetermined distance between principal surfaces, each group consisting of two lenses, both of which are arranged in the lateral direction of the camera field of view of the television camera. It is composed of cylindrical lenses that have a lens effect in the vertical direction or in the vertical direction, and when the focal length of each lens is fls r2, there is a relationship of fl・f2<0, and among both lens groups, the measurement The cylindrical lens constituting the lens group on the object side has a curved surface equidistant from both the front and back surfaces, and the convex side of this curved surface faces the measurement object side. A technical measure is taken to attach a magnification imaging lens device to the television camera.

[For production]

The shape measuring device using the light cutting method according to the present invention is configured as described above, so that, for example, a television camera can be set so that the horizontal direction of the camera field of view is the length direction of the light cutting line generated on the object to be measured. The cylindrical lenses constituting the two lens groups of the unequal magnification imaging lens device attached to this television camera are arranged so that they have a lens effect (refraction effect) in the horizontal direction of the camera field of view. In this case, in the vertical direction of the camera field of view, the light beam from the light cutting line is formed into an image due to the lens effect (refraction) of the camera lens of the television camera, whereas in the horizontal direction of the camera field of view, Due to the lens effect of the two lens groups using cylindrical lenses, the imaging magnification is smaller than that in the vertical direction, and the camera field of view in the horizontal direction is expanded. As a result, compared to the case of a TV camera alone, the length of each light section line on the imaging plane of the TV camera is reduced, and the camera field of view is expanded in the length direction (lateral direction) of the light section line. An image of the optical cutting line in the state in which the image is displayed is formed.

Thereby, it is possible to obtain an image in which a light section line spanning the entire measurement area is captured while ensuring the required measurement resolution in the vertical direction of the camera field of view. In this case, the cylindrical lens constituting the lens group on the measurement object side of the lens device for vertical and horizontal unequal magnification, or its surfaces equidistant from both the front and back surfaces, is assumed to form a curved (curved) surface. By arranging it toward the convex side of the surface or toward the object to be measured, aberrations at the periphery of the field of view are removed, and a blur-free light section image can be obtained.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 is an explanatory diagram of the configuration of a shape measuring device using an optical cutting method, showing an embodiment of the present invention. FIG. FIG. 3 is a diagram for explaining a light section line image captured by a camera.

In Fig. 1, there is an uneven step in the direction of the radius W, and the radius W is 1.
A slit light source I is placed directly above the measurement target A of 000 mm, and the slit light from this slit light source 1 emits a radiation W perpendicular to the measurement target as shown in the figure.
The slit light is projected along the direction, and a light cutting line (bright line) S is generated at a portion where the slit light intersects with the object A to be measured. At a position where the optical axis of the slit light forms an angle θ = 60° with respect to the photon surface and the shape of the light cutting line S is viewed from the side diagonally above, a focal length f = 5 is set.
A television camera 2 equipped with a standard camera lens 2a having a diameter of 0 mm is arranged in such a manner that the horizontal direction of the camera's field of view is in the longitudinal direction of a light section line S generated on a measurement target A. In this implementation, the imaging distance by the television camera 2 is at least 0.5 to measure the unevenness of the object A.
Since a measurement resolution N of mm is required, it is set to 2 m as described in the explanation regarding FIG. Reference numeral 5 denotes a lens device for forming an image with unequal magnification in the vertical and horizontal directions, which is mounted in front of the camera lens 2a of the television camera 2.

The lens device 5 for imaging with unequal vertical and horizontal magnification includes a camera lens 2a.
Two lens groups, a camera lens side lens group 5a and a measurement object side lens group 5b, are fitted in order from the camera lens 2a side into a frame (not shown) that can be attached and detached from the frame body with a distance d between principal surfaces. It is what it is. Among these, the camera lens side lens group 5a is a double cylindrical lens having a focal length f = 90 mm, which is arranged in a posture that has a lens effect (refraction effect) in the lateral direction of the camera field of view of the television camera 2. It consists of a convex lens. Measurement object side lens group 5
b is composed of two cylindrical plano-concave lenses that have a negative focal length of -60 mm and have equidistant surfaces or curved surfaces from both the front and back surfaces, and the combined focal length f2 is ft=- It has a length of 30 mm. These two cylindrical plano-concave lenses are both arranged so as to have a lens effect (refraction) in the lateral direction of the camera field of view of the television camera 2, with their curved surfaces facing either the convex side or the measurement target A side. There is. Both lens groups 5a and 5b composed of such cylindrical lenses have a distance d between their principal surfaces of d=L+fz=6.
They are arranged so as to satisfy the relationship of 0 mm. Therefore, by this lens device 5 for imaging with unequal magnification in vertical and horizontal directions, the vertical and horizontal magnification ratio M=(imaging magnification in the vertical direction of the camera field of view)/(camera A light cutting line S with different imaging magnifications in the vertical and horizontal directions, where the value of M, expressed as the imaging magnification in the horizontal direction of the field of view, is 3.
images will be formed. Note that the vertical and horizontal magnification ratio M is given by M=lfl,/f2l.

Reference numeral 3 denotes a signal processing device which processes the light section line image signal from the television camera 2 equipped with the lens device 5 for imaging with unequal vertical and horizontal magnification according to a well-known procedure, and measures the irregularities and steps of the measurement object A. This is a device that outputs the results. Signal processing device 3
is an A/D converter that performs A/D conversion of the light section line image signal from the television camera 2, a CPU, a ROM in which a control program is stored, and the A/D converted light section line image signal is stored. This is a known device equipped with a RAM and an output interface for outputting measurement results to a printer or the like. A monitor television 4 is connected to the signal processing device 3 and displays the optical cut line image signal from the television camera 2.

In a shape measuring device having such a configuration, as shown in FIG. When capturing an image, the lens device 5 for forming an image with unequal magnification in vertical and horizontal directions
Due to the lens effects of the two lens groups 5a and 5b, compared to the case where the television camera 2 is used alone as shown in FIG.
As shown in FIG. 2, an image of the light section line S is obtained in a state where the field of view is expanded three times in the length direction of the light section line S (lateral direction of the camera field of view). In this case, TV camera 2
Compared to the case of a single camera, the imaging magnification in the horizontal direction of the camera field of view is 1/3 of that in the vertical direction, and the length dimension of each light cutting line S is reduced to 1/3. There is.

As a result, the required measurement resolution N is secured in the vertical direction of the camera field of view, and the optical cutting line S covering the entire measurement area can be imaged. In addition, the measurement object side lens group 5b of the lens device 5 for unequal magnification in the vertical and horizontal directions is constituted by a cylindrical plano-concave lens whose surfaces equidistant from both the front and back sides form a curved surface, and the convex side of this curved surface is measured. Since it is arranged to face the object A side, aberrations at the periphery of the visual field are removed, and a light section line image without blur can be obtained.

In this way, the optical cutting line S over the entire measurement area generated in the measurement object A is imaged, and the optical cutting line image signal is given from the television camera 2 to the signal processing device 3, and the signal processing device 3 performs a well-known procedure. Each uneven step on the object to be measured is measured. As a result, according to the apparatus of this embodiment, while securing the required measurement resolution, a light section line image covering the entire measurement area can be obtained using a single TV camera equipped with a lens device for imaging with unequal vertical and horizontal magnifications. This eliminates the need to line up multiple TV cameras to expand the field of view, and significantly reduces measurement time.

In addition, in the above embodiment, a cylindrical biconvex lens and a cylindrical plano-concave lens were used as the cylindrical lenses constituting the two lens groups of the lens device for unequal vertical and horizontal magnification, but the invention is not limited to these. , various optimally designed cylindrical lenses may be employed.

〔Effect of the invention〕

As described above, in the shape measuring device using the light sectioning method according to the present invention, a television camera with a camera lens for imaging a light section line is equipped with a lens with unequal magnification in the vertical and horizontal directions, which is equipped with two lens groups each composed of a cylindrical surface lens. Since the configuration is equipped with an imaging lens device, it is possible to secure the required measurement resolution and to obtain a light section image with the horizontal or vertical size of the camera field of view expanded to match the object to be measured. You can get it. In addition, the cylindrical lens constituting the lens group on the measurement object side of the lens device for unequal vertical and horizontal magnification is made to form an equidistant surface or a curved surface from both the front and back surfaces, and the convex side of this curved surface is Since the camera is placed facing the object to be measured, even when the camera field of view is expanded, 1. Aberrations at the periphery of the field of view are removed, and a blur-free light section image is obtained.

As a result, according to the shape measuring device according to the present invention, a single television camera equipped with a lens device for imaging with unequal magnification in vertical and horizontal directions can generate a light section line image over the entire measurement area while ensuring the required measurement resolution. This eliminates the need to line up multiple TV cameras to expand the field of view.
An excellent effect can be obtained in that the measurement time can be significantly shortened.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a shape measuring device using an optical cutting method, showing an embodiment of the present invention, and FIG. 2 is a television camera equipped with the lens device for imaging with unequal vertical and horizontal magnification shown in FIG. 1. 3 is a diagram for explaining a light section line image taken by a television camera of a conventional shape measuring device, and FIG. 4 is a diagram for explaining a light section line image taken by a television camera of a conventional shape measuring device. FIG. 2 is a configuration explanatory diagram of a conventional shape measuring device. ■・Slit light source, 2-TV camera, 2a-camera lens, 3-signal processing device, 4-monitor TV, 5-lens device for imaging with unequal vertical and horizontal magnification, 5a camera consisting of one cylindrical biconvex lens Lens side lens group, 5b-Measurement object side lens group composed of two cylindrical plano-concave lenses, A.-Measurement object, S-light cutting line. Patent applicant Kobe Steel, Ltd.

Claims (1)

[Claims] (1) A slit light source that projects slit light onto the measurement target, and a slit light source that is placed at a predetermined position off the optical axis of the slit light source to image the light cutting line created by the slit light at the part that intersects with the measurement target. In a shape measuring device using a light cutting method, which is equipped with a television camera and measures the shape of an object to be measured based on a light cutting line image signal from the television camera, one group is composed of one or more lenses. , comprising two lens groups arranged with a predetermined distance between principal surfaces, both lens groups having a lens effect in the horizontal direction or in the vertical direction of the camera field of view of the television camera. While composed of cylindrical lenses,
When the respective focal lengths are f_1 and f_2, f_1・
It has a relationship of f_2<0, and the cylindrical lens constituting the lens group on the measurement target side of both lens groups has a curved surface with equidistant surfaces from both the front and back sides, and this curved surface A shape measuring device using a light sectioning method, characterized in that a lens device for imaging with unequal vertical and horizontal magnification, which is arranged with the convex side facing the object to be measured, is attached to the television camera.