JP2022165078A - Three-dimensional measuring device, system, and manufacturing method for article - Google Patents

Abstract

To achieve a three-dimensional measuring device capable of measuring a distance with high accuracy using a projector including a plurality of diffractive optical elements.SOLUTION: The three-dimensional measuring device includes a projection unit including a plurality of diffractive optical elements for projecting dot patterns that differ from each other on an object to be measured, a first imaging unit and a second imaging unit for capturing images of the object to be measured, and a calculation unit for generating three-dimensional data of the object to be measured by matching a plurality of images obtained by capturing images with the first imaging unit with a plurality of images obtained by capturing images with the second imaging unit for the object to be measured on which different dot patterns are sequentially projected by switching the diffractive optical elements that project the dot patterns onto the object to be measured. A pattern filling ratio, which is the ratio of an area of the dot pattern to an area of a rectangular region with the pitch of the dot pattern formed by each diffractive optical element as a side is 0.64 or less in the wavenumber space of the diffracted light from the diffractive optical elements. The number of diffractive optical elements is 4 or more.SELECTED DRAWING: Figure 6

Description

TECHNICAL FIELD The present invention relates to a three-dimensional measuring apparatus and the like equipped with a projector.

Conventionally, the correspondence between each area on two images taken by a stereo camera is calculated by a method such as block matching, and the obtained correspondence is used to measure the distance to the surface of the measurement object based on the principle of triangulation. There are known techniques for Generally, in block matching, matching is performed by approximating each part on an image to a plane block. Alternatively, a pattern is projected onto the surface of the object to be measured to give a two-dimensional feature to the surface, and block matching is performed using images of the object to be measured taken by a stereo camera. However, in the case of a shape with severe unevenness such as a thin shape or a small shape, it becomes difficult to approximate a flat block, and the accuracy of distance measurement may decrease.

On the other hand, in Patent Literature 1, patterns are switched temporally for projection, and matching is performed by adding information on temporal luminance changes of pixels on the image, thereby setting the spatial size of the block to be small. making it possible. Accordingly, techniques for measuring thin shapes and small shapes are disclosed. As a configuration for temporally switching projection patterns, it has been proposed to arrange and switch between a plurality of projectors composed of lasers and diffraction optical elements.

On the other hand, in Patent Document 2, in order to solve the problem that the projection pattern size changes according to the distance to the measurement object, by switching the diffractive optical element that projects the pattern, the projection pattern of the long distance is changed from the short distance. I am trying to increase the density. It is proposed to obtain an accurate distance value thereby.

Japanese Patent No. 6735615 JP 2014-9997 A

Generally, in the case of a projector (DOE projector) composed of a laser and a diffractive optical element (DOE), the pattern density that can be projected is a periodic and sparse pattern. As in Patent Document 1, even if the projection pattern is switched temporally and matching is performed by adding information on the temporal luminance change of pixels, if the projection pattern density is sparse, an appropriate pattern must be set to block the block. The effect of reducing the spatial size is limited. Moreover, as in Patent Document 2, there is a limit to improving the projection pattern density at a long distance with respect to the short distance.

An object of this patent is to obtain a three-dimensional measuring apparatus capable of highly accurate distance measurement by a projector including a plurality of diffractive optical elements.

In a three-dimensional measuring device,
a projection unit including a plurality of diffractive optical elements for projecting mutually different dot patterns onto a measurement object;
a first imaging unit and a second imaging unit for imaging the measurement target on which the dot pattern is projected;
By switching the diffractive optical element for projecting the dot pattern onto the measurement object, a plurality of images obtained by imaging the measurement object on which dot patterns different from each other are successively projected by the first imaging unit; a calculation unit that generates three-dimensional data of the measurement object by matching with a plurality of images obtained by imaging with a second imaging unit;
In the wavenumber space of the diffracted light from the diffractive optical element, the pattern filling factor, which is the ratio of the area of the dot pattern to the area of a rectangular area having a side equal to the pitch of the dot pattern formed by each of the diffractive optical elements, is 0. 0.64 or less, and the number of the diffractive optical elements is 4 or more.

According to the present invention, it is possible to realize a three-dimensional measurement apparatus capable of highly accurate distance measurement using a projector including a plurality of diffractive optical elements.

1 is a diagram showing a three-dimensional measuring device of Example 1. FIG. FIG. 10 is a diagram showing the concept of pattern matching using intensity information in the time direction between multiple images; 1A and 1B are schematic diagrams of the configuration of a DOE projector and image diagrams of projection patterns; FIG. FIG. 4 is a relational diagram between the structural period of the diffractive optical element within the beam diameter and the projection pattern. 4 is a schematic diagram of a projected dot pattern projected from one DOE projector of Example 1; FIG. 4A and 4B are schematic diagrams of projection patterns from each DOE projector of Example 1; FIG. 10 is a diagram showing simulation conditions in Example 2; FIG. 10 is a diagram showing the results of simulation in Example 2; FIG. 11 is a schematic diagram of projection patterns from each DOE projector of Example 3; It is a figure which shows the structural example of 2nd Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below using examples with reference to the accompanying drawings. In each drawing, the same members or elements are denoted by the same reference numerals, and overlapping descriptions are omitted or simplified.
<First embodiment>

A configuration example of a three-dimensional measurement apparatus 100 according to Example 1 of the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing a three-dimensional measuring device of Example 1. FIG.
The three-dimensional measurement apparatus 100 in FIG. 1 is a system for acquiring three-dimensional data of a measurement object 200, and includes a projection unit 110, two imaging units 121 (right camera, first imaging unit), and an imaging unit 122 ( left camera, second imaging unit), measurement control unit 130 and calculation unit 140 . The projection unit 110 and imaging units 121 and 122 are arranged facing the measurement object 200 .

The projection unit 110 is composed of four DOE projectors (111, 112, 113, 114), each of which includes a single-mode semiconductor laser as a light source, a collimator lens, and a diffractive optical element (DOE). there is That is, the projection unit includes a plurality of diffractive optical elements for projecting different dot patterns onto the measurement object. The image capturing units 121 and 122 are each composed of an image forming optical system and an image sensor (not shown). The measurement control unit 130 has a projection control unit 131 and an image acquisition unit 132 . Incidentally, in this embodiment, the number of DOE projectors is not limited to four, and may be four or more.

The projection control unit 131 sequentially switches and changes the four DOE projectors 111 to 114 under the condition that the relative positional relationship between the object to be measured and the imaging unit is substantially constant, and projects a plurality of different dots on the object to be measured 200. Project a pattern. A dot pattern to be projected will be described later. Furthermore, the projection control unit 131 sends an image pickup instruction signal to the image acquisition unit in synchronization with the start of lighting of each DOE projector. The measurement control unit 130 incorporates a CPU as a computer, and the CPU functions as control means for controlling the operation of each unit of the overall three-dimensional measurement apparatus 100 by executing a computer program stored in a memory. is doing.

The image acquisition unit 132 captures (acquires) a plurality of images (stereo images) of the measurement object 200 on which the dot pattern is projected by the imaging units 121 and 122 based on the imaging instruction signal from the projection control unit 131 . In this embodiment, an image is captured each time the four DOE projectors 111 to 114 are switched, and a total of eight images, four images each with the left camera and the right camera, are acquired. A total of eight stereo images captured by the image acquisition unit 132 are sent to the calculation unit 140 .

The calculation unit 140 calculates a distance map as three-dimensional data by matching from a group of images captured by a plurality of imaging devices and acquired by the image acquisition unit 132 . In the case of this embodiment, from four images of the left camera and four images of the right camera, intensity information of pixels at the same position of the left camera and the right camera are arranged in the direction of the time axis. Matching is performed using the axis change information. That is, by switching the diffractive optical element that projects the dot patterns onto the measurement object, the first imaging unit and the second imaging unit acquire images of the measurement object onto which mutually different dot patterns are sequentially projected. Then, the calculation unit 140 performs matching between a plurality of images obtained by imaging by the first imaging unit and a plurality of images obtained by imaging by the second imaging unit, thereby obtaining three-dimensional data of the object to be measured. Generate.

FIG. 2 is a diagram showing the concept of pattern matching using intensity information in the direction of the time axis between multiple images. As shown in FIG. 2, four images 1211 to 1214 from the right camera 121 and four images 1221 to 1224 from the left camera 122 are arranged along the time axis. Then, the calculation unit 140 extracts, by pattern matching, a region where the pixel-by-pixel data in the time axis direction (time series) is the same between the right camera and the left camera.

From the matching result, the difference between the positions of the pixels with matching time series patterns from each pixel of the left camera and the right camera is calculated as the parallax for each pixel, and the parallax map for each pixel is calculated. Furthermore, three-dimensional data of the object to be measured is generated by calculating a distance map from the parallax map.
The above operations are executed by the CPU as a computer in the measurement control section 130 controlling each section based on the computer program stored in the memory.

Next, the projection pattern conditions of the DOE projector in this embodiment will be described in detail.
FIG. 3 is a schematic diagram of the structure of a DOE projector and an image diagram of a projection pattern. A DOE projector 111 (or 112 to 114) is composed of a semiconductor laser 300 as a laser light source, a collimator lens 301, and a DOE 302, respectively. Divergent light emitted from a semiconductor laser 300 is collimated by a collimator lens 301 and then made incident on a DOE 302 to generate diffraction patterns such as zero-order diffracted light 310, first-order diffracted light 311, second-order diffracted light 312, and the like.

A single mode semiconductor laser is used as the semiconductor laser. A beam emitted from a semiconductor laser is a Gaussian beam having a Gaussian intensity distribution in a plane perpendicular to the traveling direction of light. Here, the width of a Gaussian beam having an intensity of 13.5% or more of the maximum intensity is assumed to be the dot diameter Dk.

Next, the filling factor of the projected pattern in the wavenumber space 313 when the light from the semiconductor laser 300 as the light source is diffracted by the DOE 302 will be described. For the sake of simplicity, the projected pattern will be described as a dot pattern that is grid-arranged in the horizontal and vertical directions. Consider a rectangle in the wavenumber space 313, with the dot pitch in the vertical direction of the projected dot pattern being k0h and the dot pitch in the horizontal direction being k0w. The ratio of the area of the dot diameter Dk of each projected dot pattern to the area of the rectangle (k0h _* k0w ₎ is defined as the filling rate of the projected pattern.

That is, the pattern filling factor is the ratio of the area of the dot pattern to the area of the rectangular area having the pitch of the dot pattern formed by each diffractive optical element as one side in the wavenumber space of the diffracted light from the diffractive optical element. Conceptually, it is a quantity representing the ratio of the total area of the projected dot patterns within the measurement area to the area of the measurement area.

In FIG. 3, the projected pattern is shown as a pattern on a normalized pattern projection plane (wavenumber space 313). Here, if the beam diameter Dx incident on the DOE in real space is Dx=2√2a (variable a), the beam dot diameter Dk (projection pattern dot size) in the wavenumber space 313 is expressed by Equation (1).

又、波数空間３１３におけるドットピッチをｋ０とすると、回折光学素子の構造周期の１周期の長さＤｄｏｅは数２となる。

Further, when the dot pitch in the wave number space 313 is k0, the length Ddoe of one structural period of the diffractive optical element is given by Equation (2).

ここで、波数空間３１３におけるドット径Ｄｋに対するドットピッチ（ｋ０）の比を数３のようにｎとする。

Here, let the ratio of the dot pitch (k0) to the dot diameter Dk in the wave number space 313 be n as shown in Equation (3).

以上の関係式から、ＤＯＥの周期Ｄｄｏｅと実空間におけるＤＯＥに入射するビーム径Ｄｘは次の数４のような関係になる。

From the above relational expression, the relationship between the period Ddoe of the DOE and the beam diameter Dx incident on the DOE in the real space is given by the following equation (4).

ここで、ビーム径Ｄｘ内の回折光学素子の構造周期の数をＬとすると、ＬＤｄｏｅ＝Ｄｘとなる。
従って波数空間３１３におけるドット径Ｄｋに対するパターンピッチ（ｋ０）の比ｎは数５の条件を満たす必要がある。

Here, if the number of structural periods of the diffractive optical element within the beam diameter Dx is L, then LDdoe=Dx.
Therefore, the ratio n of the pattern pitch (k0) to the dot diameter Dk in the wave number space 313 must satisfy the condition of Equation (5).

4A, 4B, and 4C are diagrams showing the relationship between the structural period of the diffractive optical element within the beam diameter and the projection pattern, and FIGS. 2 shows projection patterns when the number of is different. In this embodiment, the incident beam to the DOE has a wavelength of 850 nm and a diameter of 300 μm, and the projection plane is a straight plane 100 mm ahead of the DOE. FIGS. 4A and 4B show cases where the number of structural periods of the diffractive optical element contained within the incident beam diameter is 3, 2, and 1.5, respectively.

Here, the number L of the structural periods of the diffractive optical element within the beam diameter is set to 2 or more, and the left and right cameras project the patterns in which the adjacent patterns are sufficiently separated as shown in FIGS. Distance measurement was performed by performing stereo matching based on the intensity time variation information for each pixel. As a result, it was confirmed that highly accurate stereo matching is possible. Furthermore, when adjacent projection patterns are close together,

It was confirmed by simulation that even with the pattern shown in FIG. 4C, stereo matching for distance measurement is possible based on the intensity temporal variation information for each pixel of the left and right cameras. On the other hand, when the number of structural periods of the diffractive optical element within the beam diameter was less than 1.5, the accuracy of stereo matching for distance measurement decreased based on the intensity temporal variation information for each pixel of the left and right cameras.

In the case of FIG. 4C, the number of structural periods of the diffractive optical element within the beam diameter is 1.5, and the projection pattern pitch k _0h =k _0w =1.1Dk. The filling factor of the projected pattern, which is the ratio of the area πDk ² /4 of the projected dot pattern to the area 1.21Dk ² of the rectangular region formed by the pitches k _0h and k _0w , is π/4.84≈0.64. Become. Therefore, if the pattern filling rate is 0.64 or less, it can be said that stereo matching for distance measurement is possible based on the intensity temporal variation information for each pixel of the left and right cameras.

In FIGS. 3 and 4, for the sake of simplification, the diffraction projection pattern in one-dimensional direction has been described, but the same can be said for the two-dimensional diffraction projection pattern.
Next, specific projection patterns will be described in detail.
The projection pattern in Example 1 will be described in detail.
FIG. 5 is a schematic diagram of a projected dot pattern projected from one DOE projector. FIG. 5 is a diagram showing nine dot patterns extracted from the entire projection pattern, and the pattern other than the nine dots is a repeated pattern of the same pattern.

The lattice shape 211 in FIG. 5 is not an actual projected pattern, but rather shows the wavenumber space divided into rectangular regions with a width of 0.7w and a height of 0.7w for ease of explanation. . The intensity distribution of each diffraction pattern (dot pattern) has a Gaussian distribution, and the diameter w of each dot 210 is the diameter at an intensity of 13.5% of the peak intensity of the Gaussian distribution. The dot pattern pitch is projected at 1.4w, and the projection pattern filling factor is 0.4.

FIG. 6 is a schematic diagram of projection patterns from each DOE projector of Example 1. FIG.
FIG. 6 shows projected dot patterns of four grid arrays projected from the respective DOE projectors (111 to 114).
Also, the projected dot patterns of the respective DOE projectors are shifted in the measurement space by half a pitch horizontally or vertically as shown in FIGS. .

As a result, the projected patterns shown in FIGS. 6A to 6D almost occupy the projected space, and the projected dot pattern almost fills the measurement object 200 in the real space.

As a result, luminance time change information can be obtained from many pixels of the captured image of the measurement object 200 on which the dot pattern is projected, and the amount of information when performing stereo matching calculation from the images of the left and right cameras increases. Accurate distance measurement can be realized.

In this embodiment, the description has been given on the assumption that four DOE projectors are installed, but the number is not necessarily limited to four. For example, as a modification, eight DOE projectors having a projection pattern filling factor of, for example, 0.10 may be installed and arranged so as to reduce mutual overlapping of projected dot patterns. At this time, the eight DOE projectors are sequentially switched eight times to project the dot pattern onto the measurement object 200 . Alternatively, the dot pattern may be projected onto the measurement object 200 by sequentially switching four times while two DOE projectors are turned on at the same time.

In the first embodiment, the description has been given on the premise that the dot pattern projected from the DOE projector is ideally arranged as shown in FIG. In the second embodiment, the case where the projected dot pattern position of each DOE projector has an error with respect to the ideal state due to an installation error or the like will be described.
FIG. 7 is a diagram showing simulation conditions in Example 2. In this example, distance measurement simulation was performed under the conditions shown in FIG.

FIG. 8 is a diagram showing the results of the simulation in Example 2, in which the number of DOE projectors is used as a variable and the distance effective image ratio is used as an evaluation amount. Here, in the stereo images of the left camera and the right camera, the ratio of the number of pixels for which stereo matching is successful and the distance value is output to the number of pixels in the overlapping field of view is defined as the distance effective image ratio. In this simulation, each DOE projector has a dot pattern pitch of 2w with respect to the dot diameter w, which is the projected dot size. is projected.

In FIG. 8, the distance effective pixel ratio increases as the number of DOE projectors increases. Regardless of the distance measurement distance, if the number of DOE projectors is 4 or more, the distance measurement value can be successfully calculated for almost all pixels. I understand.

From this result, in each DOE projector with a projected pattern filling rate of 0.2, even if the projected dot patterns are not ideally arranged as in Example 1, the number of DOE projectors can satisfy four or more. I know it's fine. That is, if the number of DOE projectors is 4 or more, luminance time change information can be obtained from many pixels of the captured image of the measurement object 200, and the amount of information when stereo matching calculation is performed from the images of the left and right cameras. It was confirmed that high-precision distance measurement can be realized because of the increase in

In other words, it is desirable to project a high-density pattern in order to obtain time-varying luminance information from many pixels in order to perform highly accurate distance measurement, but there is a limit to how high-density a dot pattern can be projected with a DOE projector. There is Also, if the overlap of projection patterns from each DOE projector is large, luminance time change information cannot be obtained from many pixels. Under these constraints, it was confirmed by simulation that highly accurate distance measurement can be realized by satisfying the conditions that the projection pattern filling factor is 0.64 or less and the number of DOE projectors is 4 or more.

FIG. 9 is a schematic diagram of projection patterns from each DOE projector of Example 3. FIG. In Example 1, the projected dot patterns of the respective projectors (111 to 114) are spatially shifted horizontally and/or vertically. In contrast, the third embodiment is characterized in that the projected dot patterns of the respective projectors are in a mutually shifted and/or rotated relationship.

The projected dot pattern of FIG. 9(A) is the same as the projected pattern of FIG. 6(A), and FIG. 9(B) is a pattern obtained by rotating the projected dot pattern of FIG. 6(B) by −10°. 9(C) is the same pattern as FIG. 6(C), and FIG. 9(D) is a pattern obtained by rotating the projected dot pattern of FIG. 6(D) by +10°.

Such a projected dot pattern can be realized only by changing the mounting angle of the DOE that constitutes the DOE projector. Here, the horizontal direction of the planes of FIGS. 6 and 9 is defined as the baseline length direction of the stereo camera composed of the left camera and the right camera. In Example 1, since the dot patterns projected from the respective DOE projectors are in a mutually shifted relationship, the projected dot pattern pitch in the base line length direction is all the same, ie, 1.4w.

When searching for matching pixels from the images of the left camera and the right camera in the stereo matching performed when measuring the distance of the measurement object 200, the matching result is the same for each projection pattern pitch. As a result, distance measurement becomes unstable at a period determined by the projected dot pattern pitch of 1.4w. Normally, in the matching search of the left and right camera images, a parallax range in which the pitch of the projected dot pattern can be measured is determined in order to avoid indefinite distance measurement values caused by limiting the search parallax range.

In this embodiment, the dot pattern projected by each DOE projector is the same pattern in the wave number space, but is rotated by a predetermined angle or shifted by a predetermined pitch. is changing In other words, the dot patterns projected by the respective DOE projectors are set to have different pattern periods in the baseline length direction. Specifically, the projected dot pattern pitch in the baseline length direction is 1.4w in FIGS. 9A and 9C, and 1.4wcos (10°) in FIGS. 9B and 9D. Using four DOE projectors, dot patterns with two pitches are projected.

As a result, in the search for matching between the left and right camera images, the period in which the distance measurement becomes unstable is the period of the synthetic frequency determined by two pitches of 1.4w pitch and 1.4wcos (10°) pitch with respect to the baseline length direction. Expanding. Since the period of indefinite distance measurement is extended compared to the first embodiment, it is possible to expand the range of parallax search during the matching processing of the left and right cameras, and the distance measurement range can be expanded. At the same time, as in the first embodiment, the projected dot patterns from the four DOE projectors are also shifted relative to each other, and the same effect as in the first embodiment can be obtained.

In this embodiment, for the sake of simplicity of explanation, the projected dot pattern pitches of the two projectors out of the four DOE projectors are set to be the same, but this is not restrictive. For example, all DOE projectors may have different projected dot pattern pitches. In this case, it is possible to further expand the distance measurement range.
<Second embodiment>

FIG. 10 is a diagram showing a configuration example of a manufacturing system according to the second embodiment. The three-dimensional measuring device 100 is used by being attached to the tip of a robot arm 150 (grasping device) as a robot. The three-dimensional measurement apparatus 100 functions as part of a system that manufactures articles by assembling parts. The projection unit 110 of the three-dimensional measurement apparatus 100 sequentially projects dot patterns from the four DOE projectors onto the measurement object 200 placed on the support base 220, and captures the images with the imaging units 121 and 121 to acquire images.

Then, the three-dimensional measurement apparatus 100 performs time-series (in the direction of the time axis) pattern matching as shown in FIG.
The control unit 160 obtains the position, shape, and orientation of the measurement object 200 based on the three-dimensional data of the measurement object obtained from the three-dimensional measurement device 100 . Then, based on the obtained position, shape, and posture, a drive command is sent to the robot arm 150 to control the arm of the robot arm 150 and the robot hand at the tip in multiple axes.

The robot arm 150 holds (grips) the measurement object 200 with a robot hand or the like (gripping portion) at its tip, and performs movement control processing such as translation and rotation and attitude control processing. Furthermore, by performing an assembly process (assembly process) for assembling the measurement object 200 to other parts by the robot arm 150, it is possible to manufacture an article composed of a plurality of parts, such as an electronic circuit board or a machine. can. Also, by processing the moved measurement object 200, an article can be manufactured.

The control unit 160 has an arithmetic device such as a CPU as a computer and a storage device such as a memory storing a computer program for controlling the position and orientation of the measurement object 200 . Note that the control unit 160 for controlling the robot arm 150 may be provided outside the assembly manufacturing system of FIG. In addition, the measurement data measured by the three-dimensional measurement device 100 and the obtained image may be displayed on the display unit 170 .

The present invention has been described in detail above based on its preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications are possible based on the gist of the present invention. They are not excluded from the scope of the invention.
For example, in this embodiment, a semiconductor laser is used as a light source, but an edge emitting laser or a vertical cavity surface emitting laser (VCSEL) may be used.

Alternatively, a VCSEL array light source may be used. In this embodiment, the projection pattern has the same size in the vertical direction and the horizontal direction. However, if a general edge-emitting laser is used as the light source, the projection pattern has different sizes in the vertical direction and the horizontal direction. Even in such a case, the same effect can be obtained by satisfying the constitutional conditions of this patent.

It should be noted that a computer program that implements the functions of the above-described embodiments may be supplied to a three-dimensional measurement apparatus or the like via a network or various storage media for part or all of the control in this embodiment. Then, the computer (or CPU, MPU, etc.) in the three-dimensional measuring device or the like may read and execute the program. In that case, the program and the storage medium storing the program constitute the present invention.

100 Three-dimensional measurement device 110 Projection units 111 to 114 DOE projectors 121 and 122 Imaging unit 130 Measurement control unit 131 Projection control unit 132 Image acquisition unit 140 Calculation unit

Claims (6)

a projection unit including a plurality of diffractive optical elements for projecting mutually different dot patterns onto a measurement object;
a first imaging unit and a second imaging unit for imaging the measurement target on which the dot pattern is projected;
By switching the diffractive optical element for projecting the dot pattern onto the measurement object, a plurality of images obtained by imaging the measurement object on which dot patterns different from each other are successively projected by the first imaging unit; a calculation unit that generates three-dimensional data of the measurement object by matching with a plurality of images obtained by imaging with a second imaging unit;
In the wavenumber space of the diffracted light from the diffractive optical element, the pattern filling factor, which is the ratio of the area of the dot pattern to the area of a rectangular area having a side equal to the pitch of the dot pattern formed by each of the diffractive optical elements, is 0. .64 or less, and the number of said diffractive optical elements is 4 or more. The projection unit has four or more projectors each having a light source and the diffractive optical element,
2. The three-dimensional measurement apparatus according to claim 1, wherein different dot patterns are sequentially projected onto the measurement object by switching the projector that projects the dot patterns onto the measurement object. 2. The three-dimensional measuring apparatus according to claim 1, wherein said dot pattern is a grid arrangement. 2. The three-dimensional measuring apparatus according to claim 1, wherein the dot patterns different from each other have different periods in the base line length direction. A three-dimensional measurement device according to any one of claims 1 to 4;
and a robot that holds the object to be measured and performs movement control or attitude control based on the three-dimensional data of the object to be measured obtained by the three-dimensional measurement device. generating the three-dimensional data of the measurement object using the three-dimensional measurement device according to any one of claims 1 to 4;
and a step of manufacturing an article by processing the object to be measured based on the three-dimensional data.

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