JP2002296018A - Three-dimensional shape measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the shape of a three-dimensionally shaped area by a simple structure and by using the principle of common focus. SOLUTION: Bundle fiber 2 receives output light from a light source 1, transmits it, and emits it as outgoing light. An objective lens 6 condenses the outgoing light as incident light from a predetermined direction (the height direction) into the three-dimensional area. On this occasion, the focal position of the incident light is varied by varying the position of the objective lens in the height direction. Reflected light reflected from the three-dimensional area is transmitted by the bundle fiber, reflected by a beam splitter 5, and inputted into a CCD array 3. The CCD array outputs an output signal corresponding to the intensity of the reflected light. The shape of the three-dimensional area is determined according to the output signal.

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 apparatus using a confocal effect by a combination of a laser and an optical fiber. Precision, high speed, regardless of the material of
The present invention relates to a three-dimensional shape measurement device capable of performing shape measurement without contact.

[0002]

2. Description of the Related Art Conventionally, as a method of measuring a three-dimensional shape of a minute object, a method using light interference phenomenon (hereinafter referred to as a first method), a method of scanning an object surface with a spot light of a laser beam and reflecting the same. For measuring the position of light (hereinafter referred to as the second
Which uses the relationship between the focal position and the blur of an image obtained by changing the focal position of the optical system (hereinafter, referred to as
(Referred to as a third technique).

[0003]

By the way, in the first method, the measurement of the surface of the object can be performed with an accuracy equal to or less than the wavelength of the reference light to be used, but the measurement is performed using the phase difference of the light. In relation, if the object shape has a step having a size equal to or more than の of the wavelength, the phase will be discontinuous. Therefore, when the first method is used, there is a problem that the measurement range is narrowed. Furthermore, the first technique requires a plurality of interference images, and image processing is also indispensable, so that there is a problem that it takes time for measurement.

In the second technique, spot light scanning of a laser beam is basically performed by repeatedly performing triangulation of one point in a plane, and it is necessary to scan the laser beam with a galvanometer mirror or the like. Becomes complicated. In addition, the resolution in the plane depends on the spot light of the laser beam, and there is a problem that the measurement range becomes extremely narrow if the accuracy is increased.

In the third method, three-dimensional measurement can be performed at a relatively high speed. However, it is generally difficult to detect blur in an image, and the accuracy is limited.
Further, in the third method, if image processing is used to increase the accuracy, there is a problem that the measurement time increases.

[0006] Among these methods, there is a method of setting a pinhole at a focal position of an optical system. This method uses the confocal principle that the intensity of the reflected light from the object to be measured is extremely high at the position in the optical axis direction due to the pinhole. In this method, by changing the position of the object to be measured in the height direction and measuring the intensity of the light passing through the pinhole,
A three-dimensional shape can be obtained.

However, the method of installing a pinhole is basically measurement of a point by a spot, and it is necessary to perform two-dimensional scanning with a galvanometer mirror or the like.

It is an object of the present invention to provide a small three-dimensional shape measuring apparatus which can collectively scan a plane by using the principle of confocal and can reduce a measuring time.

Another object of the present invention is to provide a minute three-dimensional shape measuring apparatus having a simple configuration.

[0010]

According to a first aspect of the present invention, there is provided a shape measuring apparatus for measuring the shape of a three-dimensional area by a confocal action, and a transmitting means for receiving and transmitting output light from a light source. Light collecting means for collecting light emitted from the transmitting means as incident light on the three-dimensional area;
Focus position changing means for changing the focus position of the incident light by moving the light condensing means; and receiving reflected light reflected from the three-dimensional area via the transmission means and receiving light in accordance with the intensity of the reflected light. There is provided a shape measuring device comprising: a measuring unit for measuring a shape of a measurement object.

According to a second aspect of the present invention, there is provided a shape measuring apparatus for measuring the shape of a three-dimensional area by a confocal action, receiving and transmitting output light from a light source and emitting a plurality of output lights. Transmitting means for converging the plurality of outgoing lights onto the three-dimensional area as a plurality of incident lights; a focus position changing means for changing a focus position of the incident light; And a measuring means for receiving the reflected light reflected from the three-dimensional area via the transmission means and measuring the shape of the object to be measured in accordance with the intensity of the reflected light.

According to a third aspect of the present invention, there is provided a shape measuring apparatus for measuring the shape of a three-dimensional area by a confocal action, receiving and transmitting output light from a light source and emitting a plurality of output lights. Transmitting means for collecting the plurality of outgoing lights as a plurality of incident lights on the three-dimensional region,
Focus position changing means for changing the focus position of the incident light by moving the light condensing means; and receiving reflected light reflected from the three-dimensional area via the transmission means and receiving light in accordance with the intensity of the reflected light. There is provided a shape measuring device comprising: a measuring unit for measuring a shape of a measurement object.

In the first to third embodiments, a halogen light source or a semiconductor laser is used as the light source.

In the first embodiment, the transmission means can be realized by an optical fiber. In this case, it is preferable that both ends of the optical fiber are formed in a lens shape.

In the first and second embodiments, the transmission means can be realized by a bundle fiber in which a plurality of optical fibers are bundled, and also in this case, each of the optical fibers has both ends formed into a lens shape. Is preferred.

In the first to third embodiments, the condensing means can be realized by an objective lens using a telecentric optical system, and the focus position changing means can be realized by a voice coil motor.

In the second and third embodiments, the measuring means may include a beam splitter that reflects only the reflected light polarized in the three-dimensional area in a predetermined direction, and an intensity of the reflected light reflected by the beam splitter. And a CCD array for outputting a corresponding output signal. In this case, the CCD array has a plurality of CCD elements, and the CCD elements correspond one-to-one to the plurality of optical fibers.

In the first to third embodiments, a collimator lens for shaping output light of the light source into parallel light may be provided at a subsequent stage of the light source.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described with reference to FIG. In FIG. 1, a micro three-dimensional shape measuring apparatus according to the present embodiment includes a semiconductor laser or halogen light source (hereinafter, simply referred to as a light source) 1, a bundle fiber 2, a CCD array 3, a collimator lens 4, a beam splitter 5, an objective lens 6, An optical lens 7 and a work stage 8 are provided, and an object to be measured (work) is arranged on the work stage 8.

In the measuring apparatus shown in the figure, the output light from the light source 1 is shaped into parallel light by a condenser lens 4 using a collimator lens in order to achieve uniformity, and is incident on the bundle fiber 2.

The bundle fiber 2 is a two-dimensional bundle of polarization preserving fibers for preserving the polarization of light at equal intervals. The CCD array 3 is a two-dimensional array of CCD elements. Corresponds to the number of each bundle fiber 2 on a one-to-one basis.

The objective lens 6 uses a telecentric optical system, and can converge parallel incident light as parallel light. The objective lens 6 is driven up and down by a voice coil motor or the like, whereby the focal position on the work stage 8 can be changed.

As the beam splitter 5, for example, a polarizing filter is used, and only the reflected light reflected by the object to be measured and polarized 90 degrees from the incident light is used as the beam splitter 5.
And the reflected light is made incident on the condenser lens 7.

The reflected light emitted from the bundle fiber 2 is condensed on the CCD array 3 by the condenser lens 7. The output of each element of the CCD array 3 changes depending on the intensity of the incident light. Then, the output of each element of the CCD array 3 is processed by a personal computer (PC) or the like as a determination means to determine the shape.

The principle of confocal will be described with reference to FIG. In the illustrated example, the light emitted from the light source 21 passes through the pinhole 22 and passes through an optical system (such as the beam splitter 23 and the lenses 24 and 25) to reach the measurement target.
The reflected light returns to the optical system again, and the beam splitter 23
Through the pinhole 26 to the photodetector 27. The pinhole 23 is provided at a focal point on the light source side of the optical system. When the measurement object is at the position of the focal point of the optical system, the return light passing through the pinhole 26 is maximized.

On the other hand, when the object to be measured is out of the focus of the optical system, most of the return light returning to the pinhole 26 is blocked by the wall around the pinhole, and the amount of light decreases sharply as a whole. The light intensity can be expressed by the following equation 1 as a function of the height z. In equation 1, | V (z) | ²
Is the light intensity, k is the wave number, and sin θ is the numerical aperture of the objective lens.

[0027]

(Equation 1)

FIG. 3 shows an example of how the light intensity changes when the height z is changed. FIG. 3 shows that the sensitivity in the height direction is very high near the focal point of the optical system. Such characteristics are referred to as Optical Secti.
This is called the oning property. In the present invention, the measurement in the height direction of the measured object is performed using this principle.

In FIG. 1, both end faces of each fiber of the bundle fiber 2 are polished into a convex lens shape. Each fiber end surface functions as a pinhole. The focal point of the lens system formed by the objective lens 6, each end face of the bundle fiber 2, and the condenser lens 7 is CC
It is installed so as to connect to the position of the D array 3.

Instead of forming both ends of each fiber into a convex lens shape, a microlens array may be provided on both end faces of the bundle fiber. At this time, each lens of the microlens array and each fiber of the bundle fiber are made to correspond one to one.

By moving the objective lens 6 up and down, when the lens system corresponding to a certain fiber in the bundle fiber 2 is focused on the object to be measured, the objective lens 6 responds to the fiber by the confocal effect. CCD array 3
Strong reflected light is incident on the elements inside. Similarly, when the objective lens 6 is at another position, strong reflected light is incident on a certain element in the CCD array 3. By synchronizing the movement of the objective lens 6 and the reading of the CCD array 3,
A plurality of images observed by the CCD element corresponding to the position of the objective lens 6 are obtained.

For example, when the objective lens 6 is moved and focused on a projecting measuring object as shown in FIG. 4, the positions A, B and C of the objective lens 6 are set.
The annular images having different sizes as shown in FIG.

As shown in FIG. 5, if the elements of the CCD array 3 which are strongly reflected light are connected, contour lines of the object to be measured can be drawn. By combining images obtained by all the obtained CCD elements, a distribution in the height direction of the measured object is obtained. By associating each contour line of the obtained distribution map with the position of the objective lens, a three-dimensional shape of the measurement object can be obtained.

The resolution in the plane of the obtained three-dimensional image depends on the diameter of the fiber used for the bundle fiber 2, but can be adjusted by the magnification of the objective lens 6 and the condenser lens 7, and can be adjusted by a CCD array. Is not directly affected by the pitch between the elements.

In the measuring device shown in the drawing, the absolute value of the intensity of the reflected light is not important in principle, so that it is hardly affected by the reflectance of the surface of the object to be measured, so that the range of the object to be measured is wide.

Incidentally, a photodiode array can be used as a substitute for the CCD array. In this case, the linearity of the output of each photodiode becomes important.

As described above, although the conventional method using the confocal principle has high accuracy, it takes time to scan the entire surface, and the resolution in the plane is affected by the drive resolution of the work stage. In addition, when scanning a plane at a time, the optical system becomes complicated and the apparatus itself becomes expensive.

On the other hand, in the measurement apparatus according to the present invention, when measuring the shape of a minute area having a three-dimensional shape, not only can the surface be scanned in a lump, but also the objective lens having a light mass can be used. Since the movement is performed, the measurement time can be reduced. In addition, since an optical fiber is used, the degree of freedom in installing the device is increased.

As described above, the embodiment of the present invention has been described with respect to the case corresponding to claim 2 in which the bundle fiber 2 is used as the optical transmission means. However, the measuring apparatus according to the present invention is limited to the configuration shown in FIG. It is not something to be done. For example, the bundle fiber 2 may be replaced with another optical transmission means, for example, one optical fiber. Again, in this case,
It is preferable that both end faces of the optical fiber are formed into a convex lens shape. Further, the objective lens 6 as the light condensing means on the measurement object side does not necessarily need to be realized by one lens.

[0040]

As described above, according to the present invention, when measuring the shape of a minute area having a three-dimensional shape, not only can a plane be scanned at once, but also an objective lens having a small mass can be used. Since the movement is performed, there is an effect that the measurement time can be reduced.

In addition, in the present invention, since an optical fiber is used, there is also an effect that the degree of freedom in installing the device is increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a three-dimensional shape measuring apparatus according to the present invention.

FIG. 2 is a diagram for describing an operation principle of the three-dimensional shape measuring device shown in FIG.

FIG. 3 is a diagram showing how the light intensity changes when the height (z) is changed in the example shown in FIG.

FIG. 4 is a diagram for explaining an operation when an objective lens is moved to focus on a measurement target in the measurement device shown in FIG. 1;

FIG. 5 is a diagram showing an example of an image of a CCD array obtained by moving the objective lens shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser or halogen light source (light source) 2 Bundle fiber 3 CCD array 4 Collimator lens 5 Beam splitter 6 Objective lens 7 Condensing lens 8 Work stage

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA06 AA53 BB05 DD02 DD06 FF01 FF10 GG02 GG06 HH04 HH13 JJ01 JJ03 JJ05 JJ09 JJ26 LL02 LL30 LL33 LL59 MM14 PP22 QQ25 QQ31 SS13 UU03 UU00 CB

Claims (10)

[Claims] 1. A shape measuring device for measuring the shape of a three-dimensional region by a confocal action, comprising: a transmission unit for receiving and transmitting output light from a light source; Focusing means for focusing light as incident light on the area; focus position changing means for changing the focal position of the incident light by moving the focusing means; and reflecting light reflected from the three-dimensional area. And a measuring means for measuring the shape of the object to be measured in accordance with the intensity of the reflected light received via the transmitting means. 2. A shape measuring device for measuring a shape of a three-dimensional region by a confocal action, comprising: a transmitting unit that receives and transmits output light from a light source and emits a plurality of emitted lights; One condensing means for condensing the emitted light on the three-dimensional area as a plurality of incident lights; a focus position changing means for changing a focal position of the incident light; and a reflecting light reflected from the three-dimensional area. And a measuring means for measuring the shape of the object to be measured in accordance with the intensity of the reflected light received via the transmitting means. 3. A shape measuring device for measuring a shape of a three-dimensional region by a confocal action, comprising: a transmitting unit that receives and transmits output light from a light source and emits a plurality of output lights; Focusing means for focusing the emitted light on the three-dimensional area as a plurality of incident lights; focus position changing means for changing the focusing position of the incident light by moving the focusing means; And a measuring means for receiving reflected light reflected from the device via the transmitting means and measuring the shape of the object to be measured in accordance with the intensity of the reflected light. 4. The shape measuring apparatus according to claim 1, wherein said transmission means is an optical fiber. 5. The transmission means according to claim 2, wherein said transmission means comprises a bundle fiber in which a plurality of optical fibers are bundled.
Or the shape measuring device according to 3. 6. The shape measuring device according to claim 4, wherein both ends of the optical fiber are formed into a lens shape. 7. The apparatus according to claim 1, wherein the condensing means is an objective lens using a telecentric optical system.
The shape measuring device according to any one of claims 1 to 3. 8. A beam splitter for reflecting only reflected light polarized in the three-dimensional area in a predetermined direction, and an output signal corresponding to the intensity of the reflected light reflected by the beam splitter. 4. The shape measuring apparatus according to claim 2, further comprising a CCD array. 9. The shape measuring apparatus according to claim 8, wherein said CCD array has a plurality of CCD elements, and said CCD elements correspond one-to-one to said plurality of optical fibers. 10. The shape measuring apparatus according to claim 1, wherein a collimator lens for shaping output light of the light source into parallel light is provided at a subsequent stage of the light source.