JPH05288525A - Three-dimensional shape measuring device - Google Patents

Abstract

PURPOSE:To precisely measure the three-dimensional shape of a measured object on a real-time basis. CONSTITUTION:A three-dimensional shape measuring device is provided with a semiconductor laser 1 generating a laser beam, a polygon mirror 3 performing the one-dimensional scanning on the laser beam from the semiconductor laser 1, relay lenses 6, 7 focusing the outgoing light of the polygon mirror 3 at the preset positions, a rotary plane mirror 8 arranged at the focal points of the relay lenses 6, 7 to perform the two-dimensional scanning, relay lenses 11, 12 and a light projecting lens 13 radiating the outgoing light of the mirror 8 to the surface of an object 15, a condensing lens 18 guiding the reflected light from the surface of the object 15 to the mirror face of the rotary plane mirror 8, field lenses 19, 20, and a position detecting element 21 arranged at the focal position of the field lens 20 on the reflection optical path of the rotary plane mirror 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for three-dimensionally measuring the shape of an object, and more particularly to a technique effective for non-contactly measuring the three-dimensional shape of a three-dimensional object. ..

[0002]

2. Description of the Related Art A stereo method is one of the methods for three-dimensionally measuring the shape of an object without contact. In this method, corresponding points are obtained from two images corresponding to both eyes by, for example, a correlation operation, the distance from the coordinates (parallax) to the object is calculated, and the scene initially expressed as brightness information is distance information. 3D information is obtained by converting the image into a distance image with pixel values representing the degree of perspective and using this as powerful information for separating and structuring the object.

[0003]

According to the study by the present inventor, the three-dimensional shape measuring technique of an object by the stereo method takes a long time for measurement, the measurement accuracy is poor, and the measurement point is not clear. There's a problem.

Therefore, an object of the present invention is to provide a technique capable of measuring a three-dimensional shape with high accuracy and in real time.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0006]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, a laser light source for generating a laser beam, a first rotary mirror for performing one-dimensional scanning with respect to the laser beam from the laser light source, and a first rotary mirror for focusing light emitted from the rotary mirror at a predetermined position. No. 1 optical system, a second rotating mirror arranged at the focal point of the first optical system for two-dimensional scanning, and a second rotating mirror for irradiating the surface of the object to be measured with light emitted from the rotating mirror. Optical system, a third optical system that guides the reflected light from the surface of the object to be measured to the mirror surface of the second rotating mirror, and the focus position of the third optical system and the second rotating mirror. And a position detecting element disposed on the reflected optical path of the.

[0008]

According to the above-mentioned means, the beam from the laser light source is scanned in the horizontal direction when reflected by the first rotating mirror, and then is scanned in the vertical direction by the second rotating mirror. The surface of the object to be measured is irradiated through the optical system, and the reflected light from the object surface is incident on the mirror surface of the second rotating mirror through the third optical system that focuses on the position detection element, and the reflection thereof is performed. Light is incident on the position detection element. Therefore, it becomes possible to measure the three-dimensional shape with high accuracy and in real time.

[0009]

1 is a perspective view showing an embodiment of a three-dimensional shape measuring apparatus according to the present invention. 2 is a front view of the embodiment shown in FIG. 1, and FIG. 3 is a side view.

A collimator lens 2 is arranged on the emission optical path of the semiconductor laser 1, and a polygon mirror 3 for lateral scanning is arranged on the emission optical path of the collimator lens 2. The polygon mirror 3 rotates using a motor 4 as a drive source. In order to detect this rotation speed, a rotary encoder 5 is attached to the motor 4, and its detection signal is sent to a control unit (not shown).

On the reflection optical path of the polygon mirror 3, the first
The relay lens 6 (L ₁ ) and the relay lens 7 (L ₂ ) as an optical system are sequentially arranged (the relay lens 7 has the same shape as the relay lens 6 and is located at a focal length position twice that of the relay lens 6). A rotary plane mirror 8 for vertical scanning is arranged on the output optical path of the relay lens 7. An optical system is formed so that the light emitted from the rotary plane mirror 8 and the light incident on the polygon mirror 3 are orthogonal to each other. A motor 9 serving as a drive source is connected to the rotary shaft of the rotary flat mirror 8, and a rotary encoder 10 is attached to the motor 9, and a detection signal thereof is sent to a control unit (not shown).

Relay lenses 11 (L ₃ ) and 12 (L ₄ : relay lens 12 are provided on the reflection optical path of the rotating plane mirror 8.
Has the same specifications as the relay lens 11 and is placed at a focal position twice as large as that of the relay lens 11), and the projection lens 13 (projects a laser beam on the exit optical path of the relay lens 12). L ₅ ) is disposed on the focal position of the relay lens 12 (the above relay lenses 11 and 12).
And the light projecting lens 13 forms a second optical system). Laser beam 1 projected by the projection lens 13
4 is irradiated onto an object 15 having an uneven surface shape and becomes a laser beam spot 16. The laser beam spot 16 becomes reflected light 17, which is condensed by the condenser lens 18 (L ₆ ). A field lens 19 (L ₇ : the same as the relay lenses 11 and 12) is arranged at the focal position of the condenser lens 18, and a field lens 20 (L ₈ ) is arranged on the outgoing optical path of the field lens 19. Installed (above condenser lens 18, field lens 19, 2
The third optical system is formed by 0), and the rotary plane mirror 8 is positioned so as to be on this outgoing optical path.

A position detecting element (SPD) 21 is arranged at the focal position of the field lens 20.

Next, the operation of the embodiment having the above configuration will be described.

As shown in FIG. 3, the laser beam generated by the semiconductor laser 1 is incident on a point A on one surface of the polygon mirror 3 and reflected in the direction of the solid line shown in the figure. By scanning in the horizontal direction by this polygon mirror 3,
One-dimensional scanning is performed centering on the focus of the relay lens 7. Here, the relay lens 6 is arranged so that the focal position of the collimator lens 2 becomes the reflection point A on the polygon mirror 3.
Is placed, the laser beam is relay lens 6
After passing through, it travels parallel to the central axis of the relay lens 6.

When the polygon mirror 3 is rotated from the solid line position to the dotted line position, the laser beam travels from the reflection point A through the right edge of the relay lens 6 shown in the figure in parallel with the axis, and the relay lens 7 To the focal position D. Since the focus position D is on the rotation axis and the rotary plane mirror 8 is arranged so that the rotation axis is perpendicular to the rotation axis of the polygon mirror 3, the laser beam is focused on the focus position D.
It is scanned two-dimensionally around the center. Further, as shown in FIG. 2, the relay lens 11 is arranged so that the point D becomes the focal position, and the relay lens 12 is
Are arranged so as to be at the confocal position, and the center of the light projecting lens 13 is located at the focus position of the relay lens 12, so that the laser beam is aimed at the object 15 from the center of the light projecting lens 13. It is scanned two-dimensionally.

The laser beam spot 16 irradiated on the object 15 is condensed by the condenser lens 18 and imaged on the main surface D ₇ of the field lens 19. The image is incident on the rotary plane mirror 8 via the field lens 19 and the field lens 20, is reflected again by the rotary plane mirror 8, and is further imaged on the position detecting element 21.

In FIG. 2, the laser beam that is scanned / projected always coincides with the optical axis of the reflected light that is condensed. Therefore, the measurement point P is determined by the distance d between the projection lens 13 and the point P on the object surface obtained by the two-dimensional geometric calculation and the vector A in the three-dimensional direction of the laser beam detected by the rotary encoder 5. Desired.

That is, the distance d is obtained by the following equation.

D = 1 / a · {(Δxb / m) + l} (1) Here, the respective constants have the relationship shown in FIG. 4, and the respective meanings are as follows.

A: Laser beam irradiation port (center of projection lens) B: Center of condenser lens C: Image point on position detecting element 21 P: Measurement point γ: Two-dimensional unit vector of laser beam l: Distance between laser beam irradiation port and center of condensing lens 18 m: Distance between center of condensing lens 18 and light receiving surface of position detecting element 21 Δx: Displacement of image point on position detecting element 21 d: Distance between laser beam irradiation port and measurement point Then, the three-dimensional unit vector of the laser beam is α (A
x, Ay, Az), the position P ′ of the measurement point P becomes P ′ = dα (2)

As described above, the reflection point on the object 15 can always be imaged on the position detecting element 21, and the displacement of the image becomes three-dimensional information of the object 15.

Next, the implementation results will be described. First,
The measurement time T is calculated. Here, each value was set as follows.

Number of faces of polygon mirror 3: n Number of rotations of polygon mirror 3: m ₁ (rpm) Number of rotations of rotating plane mirror 8: m ₂ Number of pixels: 500 × 500 (value equivalent to that of television) The measurement time T = 500 ÷ (n × m ₁ ÷ 60). For example, if n = 12 and m ₁ = 10000, then T = 0.25 seconds.

Next, the resolution will be determined. Here, assuming that the measurement depth range is s (m), the one-dimensional position detecting element 2
Since the resolution of 1 is 40,000, it is represented by the resolution S = s / 40000. For example, if s = 1 m, the resolution S is 2
It becomes 5 μm.

The invention made by the present inventor has been specifically described above based on the embodiments, but the present invention is not limited to the embodiments and can be variously modified without departing from the scope of the invention. Needless to say.

In the above description, the case where the invention mainly made by the present inventor is applied to the three-dimensional shape measurement, which is the field of use of the invention, has been described, but the invention is not limited to this. It can be applied to a sensing unit that becomes visual. The application fields (application fields) thereof include image processing, visual inspection, shape recognition, and the like.

[0028]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

That is, a laser light source for generating a laser beam, a first rotating mirror for performing one-dimensional scanning with respect to the laser beam from the laser light source, and a light beam emitted from the rotating mirror for focusing on a predetermined position. No. 1 optical system, a second rotating mirror arranged at the focal point of the first optical system for two-dimensional scanning, and a second rotating mirror for irradiating the surface of the object to be measured with light emitted from the rotating mirror. Optical system, a third optical system that guides the reflected light from the surface of the object to be measured to the mirror surface of the second rotating mirror, and the focus position of the third optical system and the second rotating mirror. Since the position detecting element disposed on the reflection optical path of is provided,
It becomes possible to measure the three-dimensional shape with high accuracy and in real time.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a three-dimensional shape measuring apparatus according to the present invention.

FIG. 2 is a front view of the embodiment shown in FIG.

FIG. 3 is a side view of the embodiment shown in FIG.

FIG. 4 is an explanatory diagram showing a method of calculating a position vector of a measurement point.

[Explanation of symbols]

 1 Semiconductor Laser 2 Collimating Lens 3 Polygon Mirror 4,9 Motor 5,10 Rotary Encoder 6,7,11,12 Relay Lens 8 Rotating Flat Mirror 13 Projecting Lens 14 Laser Beam 15 Object 16 Laser Beam Spot 17 Reflected Light 18 Condensed Lens 19, 20 Field lens 21 Position detector

Claims (3)

[Claims] 1. A laser light source for generating a laser beam,
A first rotating mirror that performs one-dimensional scanning with respect to a laser beam from the laser light source, a first optical system that focuses light emitted from the rotating mirror to a predetermined position, and a focus of the first optical system. A second rotating mirror arranged at a position for two-dimensional scanning, a second optical system for irradiating the surface of the object to be measured with light emitted from the rotating mirror, and reflection from the surface of the object to be measured. A third optical system that guides light to the mirror surface of the second rotating mirror, and a position detecting element that is disposed at the focal position of the third optical system and on the reflected light path of the second rotating mirror. A three-dimensional shape measuring device characterized by being provided. 2. The three-dimensional shape measuring apparatus according to claim 1, wherein the first rotating mirror is a polygon mirror, and the second rotating mirror is a rotating plane mirror. 3. A rotary encoder is provided in each of the first and second rotary mirrors, and the position vector of the measurement point is calculated based on the three-dimensional direction vector of the laser beam detected by the rotary encoder. Item 3. The three-dimensional shape measuring apparatus according to item 1.