JP2003185420A - Method and apparatus for measuring three-dimensional shape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for measuring a three- dimensional shape wherein the three-dimensional shape can be measured with satisfactory accuracy. <P>SOLUTION: A light source 2 such as a white light source which can generate low-coherence light in a coherence length of 1 mm or less is installed. A pattern formation means 3 which is arranged on the optical axis of the light source 2 and which is used to form slit light on the basis of the light from the light source 2 is installed. A projection lens 4 by which the slit light is condensed with reference to a measuring object 5 is installed. An imaging optical system 6 is installed by which the three-dimensional shape of the measuring object 5 is measured on the basis of reflected light from the measuring object 5 due to the slit light. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional shape measuring method and a three-dimensional shape measuring apparatus for measuring the three-dimensional shape of electronic parts, solder bumps, and conductive paste by a light cutting method.

[0002]

2. Description of the Related Art There is a demand for non-contact measurement of a three-dimensional shape of an object to be measured, such as electronic parts, in order to inspect all of the object without damage and to speed up the inspection. The light-section method is known as one of such measurement methods.

According to the above-mentioned optical cutting method, slit light is projected onto an object to be measured on a measuring table, a light section image reflected from the object to be measured is captured by a camera as image data, and the object to be measured is based on the principle of triangulation. This is a method for obtaining a three-dimensional shape (position of irregularities) on the surface of an object, and is used for apparel and medical inspection devices.

Further, in the above-mentioned light cutting method, a method (pattern light projection method) of simultaneously projecting a plurality of slit light beams (hereinafter, multi-slit light beams) onto an object to be measured rather than one slit light beam is used. It is valid. This is because it is possible to measure a plurality of points at the same time and significantly reduce the measurement time.

Conventionally, in the three-dimensional shape measurement using the optical cutting method, a laser light source is often used as a light source from the viewpoint of high brightness and light condensing characteristics. As shown in FIG. 8, the spot light emitted from the laser light source 14 is converted into a single slit light by a slit forming means 15 such as a cylindrical lens, and a multi-slit light 17 is formed by a scanning mechanism 16 such as a polygon mirror. Was used.

[0006]

The height resolution required in fields such as apparel and medical treatment is often about several mm to several hundreds of μm. With the above-mentioned height resolution, a measurement method using a laser light source as a light source is used. It is possible to measure with high accuracy.

However, since the height resolution of several μm to several tens of μm is required for measuring the three-dimensional shape of electronic parts, solder bumps, conductive paste, etc., the image pickup optical system has a high magnification, and the laser is used as a light source. When the light source is used, the light section image captured by the high coherence of the laser light and the unevenness of the measurement target contains speckles.

Therefore, since the luminance line profile contains noise due to the speckle, the reliability of the measurement result deteriorates, and accurate measurement may not be possible.

As an example, when a laser light source is used as a light source and a V-groove work having a height of about 50 μm is used as an object to be measured, a light section image is shown in FIG. 9, and a luminance line profile is shown in FIG.
FIG. 11 shows the shape measurement result. Further, in the configuration using the laser light source as the light source and using the multi-slit light, since the scanning mechanism is required to form the multi-slit light, the control and the configuration become complicated, and the cost also increases. .

[0010]

The three-dimensional shape measuring method of the present invention is, in order to solve the above-mentioned problems, a three-dimensional shape measuring method using an optical cutting method, in which a low coherent light source is used as compared with a laser beam. The slit light is projected onto the measurement target, and the three-dimensional shape of the measurement target is measured based on the reflected light from the measurement target due to the slit light.

According to the above method, since a light source having a lower coherence than that of the laser beam is used, speckles are reduced in the imaged light section image as compared with the conventional method, and the luminance line profile of the light section image is reduced. Noise is suppressed compared to the conventional case, and the shape becomes closer to a Gaussian distribution.

As a result, in the above method, the height resolution is 50 μm or less, which is a high-definition measurement object of several μm.
It is possible to perform highly accurate measurement even in three-dimensional shape measurement of electronic components, solder bumps, conductive paste, etc., which requires a resolution in the height direction of 10 to several tens of μm.

In the above measuring method, the slit light is
There may be a plurality. According to the above method, the measurement can be made efficient by using a plurality of slit lights.

In the above measuring method, the slit pattern corresponding to the shape of the slit light may be formed by the photoetching method. According to the above method, by forming the slit pattern by the photoetching method, it is possible to improve the accuracy of the slit pattern and improve the measurement accuracy.

In the above measuring method, the light source is preferably a white light source. According to the above method, since the white light source is used as the light source, an electronic component that requires a resolution in the height direction of several μm to several tens of μm, which is a high-definition measurement target whose height resolution is 50 μm or less, In the three-dimensional shape measurement of the solder bump, the conductive paste, etc., the measurement can be performed with higher accuracy.

Moreover, unlike the prior art, in order to form multi-slit light by using laser light, a scanning mechanism and its control are required, whereas the method of the present invention is different from laser light. In order to form multi-slit light using a low-coherent light source, it suffices to project through a slit pattern, so that the measurement device can be simple in structure and inexpensive.

In order to solve the above-mentioned problems, the three-dimensional shape measuring apparatus of the present invention is arranged with a light source and an optical axis of the light source,
Pattern forming means for forming slit light by the light from the light source, a light projecting lens for condensing the slit light to the measurement object, based on the reflected light from the measurement object by the slit light It has a detection part for measuring the three-dimensional shape of the measurement object, and the light source is characterized by generating low coherent light having a coherence length of 1 mm or less.

According to the above construction, the light source emits low-coherent light having a coherence length of 1 mm or less. Therefore, as described above, the high resolution measurement object having a height resolution of 50 μm or less. It is also possible to perform highly accurate measurement in three-dimensional shape measurement of electronic components, solder bumps, conductive paste, etc., which requires a resolution in the height direction of several μm to several tens of μm.

In the above-mentioned three-dimensional shape measuring apparatus, a reflection that bends the optical axis of the optical path on the optical path between the optical axis and the measurement object or between the measurement object and the detection unit. It is preferable that an optical system is provided.

According to the above construction, by providing the reflection optical system and bending the optical axis of the optical path while securing the optical path length for measurement, the entire optical path system, that is, the entire apparatus can be miniaturized.

In the above-mentioned three-dimensional shape measuring apparatus, it is desirable that a plurality of the detecting units be provided.

According to the above construction, even if at least a part of the measuring object becomes invisible (becomes a blind spot) due to an obstacle such as a wall near the measuring object, a plurality of detecting portions are provided. As a result, the influence of the blind spot can be reduced, and the three-dimensional shape can be measured more accurately and stably.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a three-dimensional shape measuring method and a three-dimensional shape measuring apparatus according to the present invention will be described below.

(First Embodiment) FIG. 1 is a configuration diagram of a three-dimensional shape measuring method and a three-dimensional shape measuring apparatus according to a first embodiment of the present invention. In the above three-dimensional shape measuring apparatus, as shown in FIG. 1, a light projecting optical system 1 is provided. The light projecting optical system 1 includes a light source 2, a pattern forming unit 3 which is an optical slit, and a light projecting lens 4 which is a condenser lens having a focal length f = 48 mm, for example.

The light source 2 may be a light source (coherence length of 1 mm or less) that is lower in coherence than laser light (coherence length of several mm or more).
A white light source such as a halogen light source or a metal halide light source (coherence length of about several μm of 10 μm or less) is preferable. Instead of the white light source, the coherence distance is 10 μm.
A light emitting diode, which is a single wavelength light source having a wavelength of m to 20 μm, may be used as the light source 2. The laser light is a single-wavelength light source, and the coherence length is about several mm for the laser diode and about 20 cm to 30 cm for the He-Ne laser.

The optical slit of the pattern forming means 3 is a slit formed by vapor-depositing a dielectric layer such as chrome, which reflects light, on a surface different from the slit portion on the surface of a substrate made of a material having excellent light transmittance such as optical glass. Is formed. An air slit may be used instead of the optical slit. The air slits are formed by forming holes in a slit shape by a laser or the like on a substrate made of a hard and opaque (light blocking) material such as stainless steel.

The light emitted from the light source 2 becomes slit light by the pattern forming means 3 on the optical axis, and the light projecting lens 4
Is collected by the light source, and the projection angle α (in the present embodiment, 0 °, that is, the measurement target 5
Is projected at an angle (normal direction) orthogonal to the surface direction of the.

The line width of the slit light projected at this time is
Determined by the projection angle α and the magnification of the projection optical system 1, if the magnification is m = (b / a) and the slit width of the pattern forming means 3 is w0, the slit beam width w = m × (w0 / cos
α). In the present embodiment, m = 1 times, (a = b =
96 mm) and a slit ray width w = 25 μm was used.

The slit light projected on the measuring object 5 is
Of the reflected components of the specularly reflected light 9, the scattered light 10, and the diffused light 11 shown in FIG. 2, the light is reflected from the surface of the measurement target 5 at a ratio according to the reflection characteristics of the measurement target 5. Of the reflected light, the light reflected at the imaging angle β (which is set to 60 degrees with respect to the normal in the present embodiment) is reflected by the imaging lens 7 as a light-section image according to the surface shape of the CCD element. Imaged at 8. An image pickup optical system (detection unit) 6 is formed by the image pickup lens 7 and the CCD element 8. The image pickup lens 7 is, for example, a CCTV having a focal length f = 50 mm.
It is a lens (video lens).

When a V-groove work having a height of about 50 μm is used as the measuring object 5, the imaged light-section image does not include speckle as compared with the conventional one, and its luminance line profile is As shown in FIG. 4, the noise is smaller than in the conventional case and has a shape close to a Gaussian distribution. Further, the result of the cross-sectional shape at this time has small variations and high reliability as shown in FIG.

The V-groove work is formed so that the V-shaped groove having a height of about 50 μm and having a V-shaped cross section is linearly bent and meandered by shaping the surface of the iron substrate. Is.

Next, the operation and effect of the first embodiment will be described. By using a white light source with low coherence (low coherence, that is, the coherence length is as short as 1 mm or less) as the light source 2, the captured light section image does not include speckle as compared with the conventional light source, and its luminance line profile Has a shape closer to a Gaussian distribution with noise suppressed compared to the conventional case.

As a result, in the first embodiment, it is possible to stably measure a three-dimensional shape with high accuracy even for a high-definition measuring object 5 having a height of about 50 μm.

Further, in the first embodiment, when the light quantity is insufficient due to the reflection characteristic of the object to be measured 5, the slit width of the pattern forming means 3 is increased to increase the light quantity to be transmitted, and instead the light is projected. The magnification of the optical system 1 can be reduced to obtain a desired slit ray width. That is, by changing the magnification of the light projecting optical system 1, it is possible to project slit light having a light amount and a line width according to the reflection characteristic of the measuring object 5.

As a result, in the first embodiment, several μm
It is possible to perform highly accurate measurement in three-dimensional shape measurement of electronic components, solder bumps, conductive paste, etc., which requires a resolution in the height direction of several tens of μm.

(Second Embodiment) A three-dimensional shape measuring method and a three-dimensional shape measuring apparatus according to a second embodiment of the present invention will be described below. FIG. 6 is a schematic configuration diagram of a three-dimensional shape measuring apparatus according to the second embodiment of the present invention. In the above three-dimensional shape measuring apparatus, as shown in FIG. 6, the light projecting optical system 1 is provided with a light source 2, a plurality of slit-shaped pattern forming means 3a, and a light projecting lens 4.
In each of the following embodiments, the same member number is given to each member having the same function as in the first embodiment, and the description thereof is omitted.

The pattern forming means 3a in the form of a plurality of slits shown in FIG. 7 is composed of a light shielding part 12 and a transmissive part 13, and only the transmissive part 13 can pass light. The light emitted from the light source 2 has a plurality of slit-shaped pattern forming means 3a on its optical axis.
Corresponding to the multi-slit light, and is projected by the light projecting lens 4 onto the measuring object 5 at the projection angle α.

The line width and slit interval of the multi-slit light projected at this time are determined by the projection angle α and the magnification of the projection optical system 1, and the magnification is m = (b / a), and a pattern of a plurality of slits. Assuming that the slit width of the forming means 3a is w0 and the slit interval is t0, the slit beam width w = m × (w0
/ Cos α), slit light interval t = m × (t 0 / cos
α). The above optical conditions are the same as those in the first embodiment except for the slit light interval (t).

The slit light projected on the measuring object 5 is
Of the reflection components of the specularly reflected light 9, the scattered light 10, and the diffused light 11 shown in FIG. 2, the light is reflected from the surface of the measuring object 5 at a ratio according to the reflection characteristic of the measuring object 5. Of the reflected light, the light reflected at the image pickup angle β is picked up by the CCD 8 as a light section image according to the surface shape by the image pickup lens 7.

Next, the operation and effect of the second embodiment will be described. In addition to the actions and effects of the first embodiment, the scanning mechanism is not necessary, so that the projection optical system 1 capable of projecting multi-slit light can be configured with a simple configuration.

By the way, when the reflection component of the object to be measured includes scattered light and diffused light other than specularly reflected light, the light section image becomes larger than the projected slit ray width, and the ratio of scattered light and diffused light is large. In this case, the adjacent light section images may not be discriminated.

Even in the case of such an object to be measured, in the three-dimensional shape measuring method of the second embodiment, the magnification of the projection optical system 1 is changed to discriminate adjacent light section images. It is possible to project the multi-slit light having the slit light interval. That is, by changing the magnification of the light projecting optical system 1, it is possible to project multi-slit light having a line width and an interval according to the reflection characteristics of the measurement object 5.

By forming the plural slit-shaped pattern forming means 3a by photo etching, multi-slit light having a complicated pattern with a small dimensional error can be obtained.
You can project more accurately.

(Third Embodiment) A three-dimensional shape measuring apparatus according to a third embodiment of the present invention will be described below with reference to FIGS. 12 and 13.

In the three-dimensional shape measuring apparatus, as shown in FIG. 12, the reflected light from the measuring object 5 is further provided on the optical path between the measuring object 5 and the imaging optical system (detection section) 6. The reflecting mirror (reflection optical system) 26 has an optical axis of the slit light projected on the measurement target 5 and an optical axis of the reflected light further reflected from the measurement target 5 incident on the imaging optical system 6. Are provided so as to be substantially parallel to each other.

By providing this mirror 26, the entire measuring apparatus (in FIG. 12, the vertical direction, that is, the direction orthogonal to the optical axis of the light reaching the object 5 to be measured from the projection optical system 1).
The size can be set small.

FIG. 1 shows a modification of the three-dimensional shape measuring apparatus.
It will be described based on 3. In the third embodiment described above, the example in which the mirror 26 is provided on the optical path between the measurement target 5 and the imaging optical system (detection unit) 6 has been described, but the present invention is not limited to the above, and for example, FIG. As shown in FIG. 6, instead of the mirror 26, a mirror (reflection optical system) that reflects the irradiation light from the projection optical system 1 on the optical path of the light from the projection optical system 1 to the measurement target 5 27 may be provided so that the optical axis of the irradiation light and the optical axis of the reflected light that is reflected from the measurement target 5 and reaches the imaging optical system 6 are substantially parallel to each other.

Further, the mirror 27 converts the irradiation light into
The measurement object 5 is incident at an incident angle α with respect to the virtual normal direction on the measurement object 5, and the reflection angle from the measurement object 5 is in the normal direction. On the other hand, it is desirable that β be set.

By providing the mirror 27, the entire measuring apparatus (in FIG. 13, the vertical direction and the horizontal direction, that is, the direction orthogonal to the optical axis of the light from the projection optical system 1 to the measurement object 5 and It is possible to set the size in the optical axis direction) small.

The three-dimensional shape measuring method according to the third embodiment is the same as the three-dimensional shape measuring method using the optical cutting method.
A white light source is used as a light source, and slit light (single slit light, multiple slit light) formed by a pattern forming unit and a post lens arranged on the optical axis is projected onto a measurement object, and the projected slit This is a method of measuring the three-dimensional shape of a measurement target by imaging light through a reflection optical system.

Another three-dimensional shape measuring method according to the third embodiment of the present invention is a three-dimensional shape measuring method using a light section method, in which a white light source is used as a light source and a pattern arranged on the optical axis thereof. The slit light (single slit light, multiple slit light) formed by the forming unit and the post lens is projected onto the measurement object through the reflection optical system, the projected slit light is imaged, and the tertiary measurement of the measurement object is performed. This is a method of measuring the original shape.

According to each of the above methods, by using the reflective optical system, the entire measuring device can be downsized.

(Fourth Embodiment) A fourth embodiment of the present invention will be described below with reference to FIGS. 14 and 15. In the fourth embodiment, a plurality of, for example, two image pickup optical systems (detection units) 6 are provided as shown in FIG. 14 in the first embodiment described above.

As a result, in the fourth embodiment, the projection optical system 1 is arranged such that the optical axis of light from the projection optical system 1 to the measurement target 5 is the measurement target 5 with respect to the measurement target 5. It is set along the virtual normal line on the object 5.

Further, each image pickup optical system (detection section) 6 is set so that the image pickup angles, which are the optical axes of the reflected light from the measurement object 5, are β and β ′, respectively. Further, the plurality of imaging optical systems 6 may be set at equal intervals (that is, equal angles) with respect to the virtual normal line on the measurement target 5.

By the way, in the three-dimensional shape measuring method using the light-section method, since the projection optical system 1 and the imaging optical system are installed at different angles from each other, an obstacle such as a wall is placed near the object to be measured. In some cases, a part of the measuring object 5 may be hidden (becomes a blind spot) due to the shadow and the measurement of the three-dimensional shape may be inaccurate.

However, by providing a plurality of imaging optical systems 6 as in the fourth embodiment, it is possible to eliminate the blind spots due to obstacles and measure the entire range of the measuring object 5. , The measurement accuracy can be improved.

In the fourth embodiment of the present invention, as shown in FIG. 15, each mirror 26 may be provided as in the third embodiment of the present invention described above. This makes it possible to improve the measurement accuracy and reduce the size at the same time.

As described above, in the three-dimensional shape measuring method according to the fourth embodiment, the white light source is used as the light source in the three-dimensional shape measuring method using the optical cutting method, and the light source is arranged on the optical axis. Slit light (single slit light, multiple slit light) formed by the pattern forming means and the post lens is projected onto a measurement object, and the projected slit light is imaged by two or more sets of imaging optical systems from different directions. Then, the three-dimensional shape of the measuring object is measured.

Another three-dimensional shape measuring method according to the fourth embodiment is a three-dimensional shape measuring method using a light section method, in which a white light source is used as a light source and a pattern arranged on the optical axis thereof. Slit light (single slit light, multiple slit light) formed by the forming means and the post lens is projected onto a measurement object through a reflection optical system, and the projected slit light is projected from two or more sets from different directions. By taking an image through the reflection optical system by the imaging optical system,
This is a method for measuring the three-dimensional shape of the measurement object.

According to each of the above methods, the accuracy of shape measurement can be improved by using two or more sets of imaging optical systems,
Further, by using the reflective optical system, the entire measuring device can be downsized.

[0062]

As described above, the three-dimensional shape measuring method of the present invention projects slit light from a light source having a coherence lower than that of laser light onto a measuring object, and the measuring object using the slit light is measured. It is a method of measuring the three-dimensional shape of the measurement object based on the reflected light from the optical cutting method.

Therefore, the above method uses a light source having a coherence lower than that of laser light, so that a three-dimensional shape can be formed with high accuracy even on an object to be measured whose required height resolution is several tens of μm or less. It has the effect of being able to measure.

Moreover, in the prior art, a scanning mechanism and its control are required to form multi-slit light using laser light, whereas in the present invention, a light source that is lower in coherence than laser light is used. In order to form multi-slit light by using, it suffices that projection is performed via a slit pattern, so that there is also an effect that a measurement device having a simple configuration and inexpensive can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment according to a three-dimensional shape measuring method and a three-dimensional shape measuring apparatus of the present invention.

FIG. 2 is an explanatory diagram regarding various reflected lights in the three-dimensional shape measuring method.

FIG. 3 is an explanatory diagram showing an example of imaging a bent and meandering V-shaped groove in the three-dimensional shape measuring method.

FIG. 4 is a graph showing a luminance line profile of an image pickup example of the V-shaped groove in the three-dimensional shape measuring method.

FIG. 5 is a graph showing the shape measurement result of the V-shaped groove in the three-dimensional shape measuring method.

FIG. 6 is a schematic configuration diagram of a second embodiment according to a three-dimensional shape measuring method and a three-dimensional shape measuring apparatus of the present invention.

FIG. 7 is a front view of a pattern forming unit having a plurality of slits in the three-dimensional shape measuring method and the three-dimensional shape measuring apparatus.

FIG. 8 is a schematic configuration diagram showing a slit light forming method in a conventional three-dimensional shape measuring method.

FIG. 9 is an explanatory diagram showing an example of imaging the V-shaped groove in the conventional three-dimensional shape measuring method.

FIG. 10 shows the above V in a conventional three-dimensional shape measuring method.
It is explanatory drawing which shows the brightness | luminance line profile of the example of imaging of a mold groove.

FIG. 11 shows the above V in a conventional three-dimensional shape measuring method.
It is explanatory drawing which shows the shape measurement result of a die groove.

FIG. 12 is a schematic configuration diagram of a three-dimensional shape measuring apparatus according to a third embodiment of the present invention.

FIG. 13 is a schematic configuration diagram of a modified example of the three-dimensional shape measuring apparatus.

FIG. 14 is a schematic configuration diagram of a three-dimensional shape measuring apparatus according to a fourth embodiment of the present invention.

FIG. 15 is a schematic configuration diagram of a modified example of the three-dimensional shape measuring apparatus.

[Explanation of symbols]

2 light sources 3 pattern forming means 4 Projection lens 5 Object to be measured 6 Imaging optical system (detection unit)

Continued front page    F term (reference) 2F065 AA04 AA53 CC25 CC26 DD02                       DD04 FF04 GG04 GG07 GG24                       HH05 HH07 HH12 JJ05 JJ08                       JJ26 LL11 LL28 QQ24

Claims (7)

[Claims] 1. A three-dimensional shape measuring method using a light section method, wherein slit light from a light source having a coherence lower than that of laser light is projected onto an object to be measured, and reflected light from the object to be measured by the slit light is projected. A three-dimensional shape measuring method characterized by measuring the three-dimensional shape of the measurement object based on the above. 2. The three-dimensional shape measuring method according to claim 1, wherein the slit light is plural. 3. The three-dimensional shape measuring method according to claim 1, wherein a slit pattern corresponding to the shape of the slit light is formed by a photoetching method. 4. The three-dimensional shape measuring method according to claim 1, wherein the light source is a white light source. 5. A light source, a pattern forming means arranged on the optical axis of the light source, for forming slit light by the light from the light source, and a projector for converging the slit light on an object to be measured. An optical lens and a detection unit for measuring the three-dimensional shape of the measurement target based on the reflected light from the measurement target due to the slit light, and the light source has low coherence with a coherence length of 1 mm or less. A three-dimensional shape measuring device characterized in that it emits various light. 6. A reflective optical system for bending the optical axis of the optical path is provided on the optical path between the optical axis and the measurement object or between the measurement object and the detection unit. The three-dimensional shape measuring apparatus according to claim 5, wherein 7. The three-dimensional shape measuring apparatus according to claim 5, wherein a plurality of the detecting units are provided.