JP2013257162A - Distance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance measuring device which allows a distance region measurable with a stereo camera to be included in a region illuminated with diffraction pattern light even when the distance to a distance measurement object is changed, achieving an accurate distance measurement using diffraction pattern light over the entire distance measurable area regardless of the distance to the distance measurement object.SOLUTION: The distance measuring device includes: a light source 2 which emits illumination light; a diffraction optical element 4 which emits pattern light 5 generated by diffraction of the illumination light to a subject; a plurality of imaging lenses 12 which image the diffraction pattern light 5 reflected by the subject; imaging means 15 which images a plurality of pictures of the subject on the basis of the diffraction pattern light 5 imaged by the imaging lenses 12; and distance measurement means 40 which calculates the distance from the subject on the basis of the parallax information among the pictures. The diffraction optical elements 4 are arranged among the optical axes of the imaging lenses 12, such that the emission angle of the diffraction pattern light becomes equal to the field angle of the imaging lenses 12.

Description

  The present invention relates to a distance measuring device including a pattern illumination device that projects diffraction pattern light onto a measurement target.

2. Description of the Related Art Conventionally, a technique called “stereo distance measurement” is known in which a measurement (distance measurement) object is photographed by two cameras and distance information to the measurement object is obtained using the two obtained images.
Such a distance measuring apparatus to which “stereo distance measurement” is applied can be suitably used for a self-propelled robot or a movable robot arm.
In “stereo ranging”, the depth distance is calculated based on the principle of triangulation using the parallax generated between two images. To obtain the parallax in stereo ranging, window matching is performed on each image. It is necessary to find points corresponding to each other (corresponding points).

14 and 15 are diagrams for explaining the principle of a distance measuring method using the principle of triangulation used in “stereo distance measurement”.
In the distance measurement method using “stereo distance measurement”, a pair of two-dimensional sensors and a pair of lenses are combined to form two cameras to detect a deviation (parallax) of a measurement object. The distance is measured by the principle of triangulation.
Consider the case where the stereo camera device 106 shown in FIG. 14 shoots light from the measurement object 101 by arranging two cameras 102a and 102b made of the same optical system.
The measurement object image 104a obtained through the lens 103a of the camera 102a and the measurement object image 104b obtained through the lens 103b of the camera 102b are different from each other in that the same point on the subject (measurement object 101) is shifted by the parallax Δ. Each of the dimension sensors 105a and 105b (FIG. 15) is received by a plurality of light receiving elements (pixels) and converted into an electrical signal.

Here, the distance between the optical axes of the lenses 103a and 103b is called a base line length, which is D, where A is the distance between the lens and the subject, and f is the focal length of the lens. Equation 1 holds.
[Formula 1]
A = Df / Δ
Since the baseline length D and the focal length f of the lens are known, the distance A to the subject can be calculated by detecting the parallax Δ using [Equation 1].
In addition, said method is a method of searching the corresponding point for the measurement object 101 reflected in the two two-dimensional sensors based on the distribution characteristics of the luminance values of the pixels.
Therefore, when the measurement object 101 is an object having a single-color surface, the luminance distribution of the surface is uniform, and it is difficult for the luminance value to change in the captured image, it is difficult to perform the association (that is, Because the corresponding point 104c shown in FIG. 15 cannot be detected), the distance cannot be calculated.

In order to deal with this problem, Patent Document 1 and Patent Document 2 disclose a technique for solving the above problem by projecting a predetermined light projection pattern toward the surface of the measurement target and applying a pattern to the surface of the measurement target. Is disclosed.
Patent Document 1 discloses a configuration in which a means for illuminating a projection pattern is provided in a distance measuring device using a stereo camera. In the technique disclosed in this document, an appropriate method is used based on a pattern or a captured image. By adopting a configuration in which a simple light projection pattern is projected, a highly accurate distance image can be obtained even for an object whose luminance value hardly changes in a captured image.

However, in the device described in Patent Document 1, the shooting area (range measurement possible area) by the stereo camera and the pattern illumination area by the pattern illumination device overlap at a specific distance, but do not overlap at other distances. There is a problem of end. For example, it can be applied when measuring a fixed distance with a fixed camera as in a factory inspection line, but it can be mounted on a self-propelled robot or a movable robot arm, and it can be applied from a short distance (1 m or less) to a medium distance. It is not suitable for applications that measure a wide distance up to (about 5m). That is, unless the object to be measured is at a certain distance, the distance cannot be measured with high accuracy.
The present invention has been made in view of the above-described problems, and can perform distance measurement with high accuracy using diffraction pattern light in the entire distance measurement area regardless of the distance to the distance measurement object. An object is to provide an apparatus.

  In order to solve the above-described problem, the invention according to claim 1 irradiates the subject with a light source that emits illumination light for irradiating the subject and diffraction pattern light generated by diffracting the illumination light. A diffractive optical element, a plurality of imaging lenses that image the diffraction pattern light reflected from the subject, and a plurality of images related to the subject based on the diffraction pattern light imaged by the imaging lenses A plurality of imaging means and a distance measuring means for calculating a distance from the subject from parallax information between the plurality of images, and the diffractive optical element is disposed between optical axes of the plurality of imaging lenses. And the diffraction pattern light can be emitted at an angle including an area where the parallax information can be acquired via the plurality of imaging lenses.

  With the configuration as described above, according to the present invention, a distance measuring device capable of performing accurate distance measurement using diffraction pattern light in the entire distance measuring area regardless of the distance to the object to be measured is realized. I can do it.

The figure which shows the structural example of the pattern illumination apparatus applicable to the ranging apparatus of this invention. The figure which showed the relationship between the cross-sectional shape of a diffractive optical element, and diffraction efficiency. The figure which shows the structure of the stereo camera applicable to the ranging apparatus of this invention. FIG. 4 is a diagram for explaining a distance measuring measure according to the present invention in which the pattern illumination device of FIG. 1 is applied to the stereo camera of FIG. 3. The figure which showed the relationship between the angle of view of a ranging lens and the emission angle of the diffraction pattern light of a pattern illumination apparatus in the ranging apparatus shown in FIG. The figure which shows the position of the 0th-order diffracted light spot in diffraction pattern light. The figure which shows the position of the 0th-order diffracted light spot image on an imaging region in a normal state. The figure which shows the position of the 0th-order diffracted light spot image when the radiation | emission direction of diffraction pattern light has shifted | deviated. The figure which shows the position of the 0th-order diffracted light spot image when the radiation | emission direction of diffraction pattern light has shifted | deviated. The figure explaining the pattern illumination apparatus which concerns on 2nd Embodiment. The figure explaining the distance measuring device concerning 3rd Embodiment. The figure explaining the distance measuring device concerning 3rd Embodiment. The figure explaining the aspect which attaches a diffractive optical element to the distance measuring device of this invention. The figure explaining the principle of the ranging method using the principle of triangulation. The figure explaining the principle of the ranging method using the principle of triangulation.

Embodiments according to the present invention will be described below in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a diagram showing a configuration example of a pattern illumination device applicable to the compound eye camera device of the present invention.
FIG. 1A illustrates each element constituting the pattern illumination device, and the display of the configuration of the compound eye camera to which the pattern illumination device can be applied is omitted. FIG. 1B is a diagram showing the gradation of the multi-gradation luminance distribution.
As shown in FIG. 1, the pattern illumination device 1 according to the present embodiment includes a semiconductor laser light source 2 as a light source, a coupling lens 3 disposed on the optical path of laser light emitted from the semiconductor laser light source 2, and diffraction. And an optical element 4.
The laser light emitted from the semiconductor laser light source 2 is converted into parallel light by the coupling lens 3 disposed on the optical path on the subject side to be measured.
The parallel light that has passed (transmitted) through the coupling lens 3 is then incident on the diffractive optical element 4 and diffracted, and is projected onto the measurement object as diffraction pattern light 5 having a luminance distribution of two or more gradations.
In order to keep the output of the semiconductor laser light source 2 constant, a temperature adjustment function unit 6a and an APC (Auto Power Control) function unit 6b for keeping the temperature constant may be provided.

By the way, in order to generate a brightness of two or more gradations in the diffraction pattern light 5 irradiated to the measurement target, the cross-sectional shape of the diffractive optical element 4 is a multi-step staircase shape having different groove depths.
As shown in FIG. 1B, the diffraction pattern light has a multi-tone luminance distribution, and the size of one pixel, which is the minimum unit, is about 1 mm square. The diffraction pattern light 5 in which the minimum unit pixels having the multi-tone luminance distribution are randomly arranged is projected onto the object to be measured (ranging).

FIG. 2 is a diagram showing the relationship between the cross-sectional shape of the diffractive optical element and the diffraction efficiency.
As shown in FIG. 2, the diffraction efficiency can be changed by changing the number of grooves (steps) in the cross-sectional shape of the diffractive optical element 4 and the depth of the steps.
Since the luminance is high (bright) in the portion where the diffraction efficiency is high and the luminance is low (dark) in the portion where the diffraction efficiency is low, the multi-tone luminance distribution can be obtained by appropriately combining the groove shape patterns in the diffractive optical element 4. Can be formed.
Note that the intensity of 0th-order light, which will be described later, can also be controlled by the shape of this groove.
As described above, a technique relating to the conversion of the light intensity (luminance) distribution using the diffractive optical element 4 is also disclosed in Japanese Patent Laid-Open No. 2003-270585 and Japanese Patent No. 4333760.

The semiconductor laser light source 2 shown in FIG. 1 can select and emit visible light having a wavelength λ of 400 to 700 nm and near infrared light having a wavelength λ of about 700 to 1000 nm.
If visible light is used, it is possible to irradiate diffraction pattern light with high sensitivity and high resolution to the imaging device of the stereo camera. On the other hand, when using near-infrared light, the sensitivity to the image sensor is low, but the laser light is not visible to the eye (invisible light), so that the user does not feel unnaturalness.
The outgoing angle θ1 from the diffractive optical element 4 is determined by the wavelength λ of the outgoing light from the semiconductor laser light source 2 and the periodic structure of the diffractive optical element 4.
In order to increase the emission angle θ1, the wavelength λ of the semiconductor laser light source 2 must be increased or the periodic structure of the diffractive optical element 4 must be miniaturized.

However, the wavelength of the emitted light from the semiconductor laser light source 2 is limited to the above-mentioned wavelength of 400 to 1000 nm, and the periodic structure of the diffractive optical element 4 is limited to the fine processing capability of the processing apparatus.
Therefore, the actual situation is that the emission angle cannot be increased beyond a certain angle.
For example, when the wavelength λ = 0.65 μm and the periodic structure is 1.0 μm, the emission angle is about 40 °.

3A and 3B are diagrams showing a configuration of a compound eye camera device applicable to the distance measuring apparatus according to the present invention, wherein FIG. 3A is a cross-sectional view of the compound eye camera device, and FIG. 3B is an image sensor included in the compound eye camera device. FIG.
Note that the present invention can be suitably applied to a stereo camera device including two cameras (an imaging lens and an imaging region) as a compound eye camera, and the stereo camera device will be described as an example.
In FIG. 3, the stereo camera device 20 receives a lens array 11 having a plurality of (for example, two) lenses arranged on the same plane, and reflected light from a subject transmitted through the lens array 11 (the subject image is And an image sensor 14 that acquires image information.
In the lens array 11, imaging lenses 12a and 12b, which are distance measuring lenses, are integrally formed.

The imaging lenses 12a and 12b have the same optical characteristics, have the same shape and the same focal length, and the optical axes 13a and 13b are parallel to each other. The interval between the optical axis 13a and the optical axis 13b is the baseline length D.
As shown in FIG. 3, the direction of the optical axes 13a and 13b is the Z axis, the direction orthogonal to the Z axis and from the optical axis 13b to the optical axis 13a is the Y axis, and both the Z axis and the Y axis are An orthogonal direction is taken as an X axis.
When the lens array 11 is arranged so that the centers of both lenses are on the Y axis, the imaging lenses 12a and 12b exist on the XY plane.
In this case, the direction in which the parallax Δ is generated is the Y-axis direction.
The imaging device 14 is an imaging device such as a complementary metal oxide semiconductor (CMOS) or a charge coupled device (CCD), and has a large number of pixels (imaging regions) formed on a wafer 14a by a semiconductor process.

As shown in detail in FIG. 3B, on the image sensor 14, an imaging region (imaging means) 15a on which a subject image is formed via the imaging lens 12a, and a subject image is formed via the imaging lens 12b. The imaging region 15b is spaced apart.
The imaging area 15a and the imaging area 15b are rectangular areas having the same size, and the diagonal centers of the imaging area 15a and the imaging area 15b are substantially coincident with the optical axes 13a and 13b of the imaging lenses 12a and 12b. Is arranged.

The stereo camera device 20 having the above configuration can measure the distance from the subject based on the principle of triangulation described above with reference to FIGS.
Further, if the pattern is illuminated by the pattern illumination device shown in FIG. 1, even if the measurement target is an object having a single color surface, stereo correspondence can be performed, so that the object can be measured with high accuracy.

4 is a diagram illustrating a stereo camera device according to the present invention in which the pattern illumination device of FIG. 1 is applied (integrated) to the stereo camera device of FIG.
4A is a cross-sectional view in the longitudinal direction (length direction of the lens array) of the stereo camera device, and FIG. 4B is a cross-sectional view in the short side direction (width direction of the lens array).
FIG. 5 is a diagram showing the relationship between the angle of view of the distance measuring lens and the emission angle of the diffraction pattern light of the pattern illumination device in the stereo camera shown in FIG.
In FIG. 4 and subsequent figures, the same components as those in FIGS. 1 and 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

The distance measuring device 30 shown in FIG. 4 is configured by combining the stereo camera device 20 described in FIG. 3 with the configuration of the pattern illumination device shown in FIG.
That is, the pattern illumination device as shown in FIG. 1 is arranged between the two cameras (the imaging lens 12a and the imaging region 15a, the imaging lens 12b and the imaging region 15b) constituting the stereo camera device 20 described in FIG. ing.
In addition, a parallax calculation unit (ranging unit) 40 that performs distance measurement based on parallax of images captured by the two cameras is provided.
As shown in FIG. 4B, the semiconductor laser light source 2 of the pattern illumination device included in the distance measuring device 30 is attached to the side surface of the housing 30 a of the distance measuring device 30. 31 is installed. The light emitted from the semiconductor laser light source 2 is reflected by the mirror 31 toward the subject to be measured, and converted into parallel light by the coupling lens 3 (see FIG. 1).
The parallel light is diffracted by the diffractive optical element 4 (see FIG. 1), is emitted as diffraction pattern light 5 having a predetermined emission angle, and is irradiated onto the object.

In the distance measuring device 30 shown in FIG. 5, the range A that can be measured is an area where the angles of view of the two imaging lenses 12 a and 12 b overlap, but the emission angle θ 1 of the diffraction pattern light 5 emitted from the diffractive optical element 4 is Since the angle is equal to the angle of view θ2 of the lenses 12a and 12b of the stereo camera device 20, even if the distance between the object and the stereo camera device 20 changes, the pattern is irradiated to the entire distance measuring area A.
Therefore, as shown in FIG. 5, distance measurement using the diffraction pattern light can be performed in the entire distance measuring area A regardless of the distance to the object to be measured.
In this way, the diffractive optical element 4 is disposed between the optical axes of the two imaging lenses 12a and 12b of the stereo camera so that the angle of view of the stereo camera and the angle of view (expansion angle) of the diffractive optical element 4 are matched. Thus, the area that can be measured by the stereo camera and the area that illuminates the diffraction pattern light can always be matched.

Thereby, even if the distance to the object changes, the area A that can be measured by the stereo camera and the area that illuminates the diffraction pattern light can always be matched. Further, it is possible to irradiate the distance measuring area A with the diffraction pattern light 5 emitted from the semiconductor laser light source 2 without waste.
Of course, the angle of view of the diffractive optical element 4 may be made larger than the angle of view of the imaging lenses 12a and 12b. However, in order to increase the angle of view of the diffractive optical element as described above, the diffractive optical element 4 Therefore, there is a problem that the periodic structure must be miniaturized and the processing capability of the processing apparatus is limited.
Moreover, the diffraction pattern light irradiated to the area | region which does not overlap with the range-measurable area | region A by a stereo camera is useless in fact.

  By the way, when the distance measuring device 30 shown in FIG. 4 is applied to a self-propelled robot, a movable robot arm, or the like, the pattern in the distance measuring device 30 may be used under severe conditions or over time. The positional relationship between the illumination device (laser light source 2, coupling lens 3, diffractive optical element 4) and imaging lenses 12a and 12b of the stereo camera is shifted, or the mounting position of the semiconductor laser light source 2 is shifted and the light emission angle Is shifted from the initial angle, the angle of view θ2 of the lens is not equal to the emission angle θ1 of the diffraction pattern light, and the region that can be measured by the stereo camera illuminates the diffraction pattern light Thus, it becomes impossible to accurately measure the entire distance range of the stereo camera.

Hereinafter, a method of detecting a positional deviation between the stereo camera (imaging lenses 12a and 12b) and the pattern illumination device (laser light source 2, coupling lens 3, and diffractive optical element 4) will be described with reference to FIGS. .
The diffraction pattern light 5 diffracted by the diffractive optical element 4 often includes zero-order diffracted light 7.
Here, the 0th-order diffracted light is light that has passed through (transmitted) without being diffracted out of the light beam incident on the diffractive optical element 4.
Originally, the diffractive optical element is designed and processed so that the 0th-order diffracted light is not generated. However, in the present invention, the 0th-order diffracted light 7 is generated intentionally and is used to generate the stereo camera device 20 (imaging lenses 12a and 12b). And pattern illuminating device 1 (laser light source 2, coupling lens 3, diffractive optical element 4) are used to detect positional deviation.

FIG. 6 is a diagram showing the position of the 0th-order diffracted light spot in the diffraction pattern light.
As shown in FIG. 6, the spot of the 0th-order diffracted light 7 usually occurs at the center of the region of the diffraction pattern light 5.
The 0th-order diffracted light 7 is light emitted from the semiconductor laser light source 2 and is emitted from an intermediate position between the optical axes 13a and 13b of the imaging lenses 12a and 12b of the stereo camera.
For this reason, in the normal state, the spot of the 0th-order diffracted light 7 appears in the imaging regions 15a and 15b of the two imaging elements of the stereo camera as shown in FIG.

FIG. 7 is a diagram illustrating the position of the 0th-order diffracted light spot image on the imaging region in the normal state.
As shown in FIG. 7, in the left imaging region 15a, a 0th-order diffracted light spot appears at a position shifted from the center of the region by a parallax L0 (0th-order diffracted light spot image 7L), and in the right imaging region 15b, the center of the region is shown. A spot of the 0th-order diffracted light 7 is reflected at a position deviated by the parallax R0 (0th-order diffracted light spot image 7R).
At this time, since the semiconductor laser light source 2 is at an intermediate position between the optical axes 13a and 13b of the lenses 12a and 12b of the stereo camera, parallax L0 = parallax R0. That is, detection is performed at a position shifted by an equal number of pixels from the centers of the screens of the two cameras.

8 and 9 are diagrams showing the positions of the 0th-order diffracted light spot images on the imaging region when the emission direction of the diffraction pattern light is deviated.
As shown in FIG. 8, when the position of the semiconductor laser light source 2 is shifted to the left side in the figure and the direction of the diffraction pattern light 5 is shifted to the + side of the Y direction (right side in the figure) (diffraction pattern light 5A), 0 next time. The spot of the folding light 7 is also shifted to the + side in the Y direction (the right side of the figure) (0th order diffracted light spot 7A).
Regarding the position of the spot image of the 0th-order diffracted light 7, the 0th-order diffracted light spot image 7L in the imaging region 15a appears at a position shifted from the center of the imaging region 15a by the parallax L1 (L1> L0), and the 0th-order diffracted light in the imaging region 15b. The spot image 7R is reflected at a position shifted by the parallax R1 (R1 <R0) from the center of the imaging region 15b. At this time, parallax L1> parallax R1.
By detecting this difference by the parallax calculation unit 40, the amount of deviation and the direction of deviation can be known as to how much the direction of the diffraction pattern light 5 and the direction of the stereo camera are deviated.

On the contrary, as shown in FIG. 9, when the position of the semiconductor laser light source 2 is shifted to the right side in the drawing and the direction of the diffraction pattern light 5 is shifted to the negative side (left side in the drawing) of the Y direction (diffraction pattern light 5B), The spot of the next-order diffracted light 7 is also shifted to the-side (left side in the figure) in the Y direction (0th-order diffracted light spot 7B).
Regarding the position of the spot of the 0th-order diffracted light 7, the 0th-order diffracted light spot image 7L in the imaging region 15a is reflected at a position shifted from the center of the imaging region 15a by the parallax L2 (L2 <L0), and the 0th-order diffracted light spot in the imaging region 15b. The image 7R appears in a position shifted from the center of the imaging region 15b by the parallax R2 (R2> R0). At this time, parallax L2 <parallax R2.
As in the case of FIG. 8, by detecting this difference by the parallax calculation unit 40, it is possible to know the amount of deviation and the direction of deviation as to how much the direction of the diffraction pattern light 5 is deviated from the direction of the stereo camera.

As described above, a shift between the direction of the diffraction pattern light and the direction of the stereo camera can be detected by detecting the position of the 0th-order diffracted light using the stereo camera.
As a result, if a deviation of more than a predetermined level occurs even under operating conditions where there is a lot of vibration, such as a self-propelled robot or a movable robot arm, the operation is immediately stopped and corrections are made. It is possible to keep the distance.
In addition, it is desirable to provide notifying means for notifying the outside by voice or light emission when a deviation occurs in the distance measuring device 30 or other devices incorporating the distance measuring device 30.

[Second Embodiment]
FIG. 10 is a diagram for explaining a pattern illumination device according to the second embodiment of the present invention.
In order to detect the direction shift between the diffraction pattern light and the stereo camera (imaging lens) using the 0th-order diffracted light 7, it is desirable to make the 0th-order diffracted light 7 easy to detect. For this purpose, the 0th-order diffracted light 7 may be made to stand out from the other spots 5a of the pattern illumination.
Therefore, the zero-order diffracted light 7 may be made larger in spot size or light intensity than the other spots 5a of the diffraction pattern light 5.
The spot size of the 0th-order diffracted light 7 is determined by the beam diameter φ of parallel light emitted from the coupling lens 3. Therefore, if the beam diameter of the parallel light emitted from the coupling lens 3 is made larger than the other spot diameters of the pattern illumination, the difference can be easily understood.
Furthermore, if the light intensity of the 0th-order diffracted light 7 is higher than that of other spots in the pattern illumination, the 0th-order diffracted light 7 will fly out in the captured image.
A distance measurement error occurs in a distance image at a spot that is skipped in a captured image. Therefore, a spot where a white spot or an error occurs can be regarded as the position of the 0th-order diffracted light.

Further, the light intensity of the 0th-order diffracted light 7 is determined by the diffraction efficiency. If the diffraction efficiency is lowered, the light intensity of the 0th-order diffracted light 7, which is the light that passes through (transmits) without being diffracted, is increased.
As shown in FIG. 2, the diffraction efficiency can be set optimally by changing the groove depth and shape of the diffractive optical element 4.
If the spot size of the 0th-order diffracted light 7 is made larger than the other spots of pattern illumination or the light intensity is increased in this way, it becomes easier to detect the misalignment between the diffraction pattern light and the stereo camera.

[Third Embodiment]
Next, a modification of the distance measuring device of the present invention will be described.
FIG. 11 is a diagram for explaining a distance measuring apparatus according to the third embodiment.
In the present embodiment, as shown in FIG. 11, the coupling lens 3 of the pattern illumination device and the pair of lenses 12 a and 12 b of the stereo camera constituting the distance measuring device are integrally formed as a lens array 8.
In this way, in addition to simplifying the assembly process, there are the following merits.
When the position of the semiconductor laser light source 2 is shifted to the + side in the Y direction with respect to the lens array 8 integrated in FIG. 11 (the original position is the position of the dotted line), the diffraction pattern light 5 and the 0th-order diffracted light 7 are 12 shifts to the negative side in the Y direction (diffraction pattern light 5C and zeroth-order diffracted light 7C).

If the diffraction pattern light 5 is shifted to the negative side in the Y direction, the shift can be detected by the stereo camera as described above.
In that case, if the position of the semiconductor laser light source 2 is corrected by moving in the -Y direction, the deviation is eliminated.
Thus, the pattern illumination coupling lens 3 and the pair of lenses of the stereo camera are integrally formed, so that the direction of the diffraction pattern light and the direction of the stereo camera are detected, and the position of the semiconductor laser light source 2 is detected. The shift can be corrected by moving.
If they are not integrated, even if a deviation is detected, it is not known whether the semiconductor laser light source 2 is deviated, the coupling lens 3 is deviated, or both are deviated, making adjustment difficult.

By integrally forming the coupling lens and the pair of lenses of the stereo camera, the lens can be used as a reference, so that even if there is a deviation, it can be easily corrected.
That is, the coupling lens 3 that takes in light from the laser light source 2 and the pair of lenses 12 of the stereo camera are integrally formed, and the direction in which the stereo camera (imaging lenses 12a and 12b) is photographing and the pattern illumination device. The direction in which the (coupling lens 3) is illuminating is detected, and even when there is a deviation, the deviation can be easily corrected.
Since the diffractive optical element 4 is formed integrally with the coupling lens 3 or the two imaging lenses 12a and 12b of the stereo camera, the stereo camera takes a picture because the positional deviation is less likely to occur with respect to vibration and changes with time. The direction and the direction illuminated by the lighting device are less likely to be shifted, and stable ranging can be performed.
By integrally forming the coupling lens and the stereo camera lens, the direction in which the stereo camera is photographing and the direction in which the illumination device is illuminating can be easily matched.
Since the diffractive optical element is formed integrally with the coupling lens or the lens of the stereo camera, it is difficult for positional deviation to occur with respect to vibration and changes over time. Direction is stable.

[Fourth Embodiment]
FIG. 13 is a diagram for explaining a mode in which a diffractive optical element is attached to the distance measuring apparatus of the present invention.
Since the shape of the diffractive optical element 4 has a fine periodic structure, it is generally processed on a glass substrate by photolithography or etching.
Therefore, the diffractive optical element 4 processed into the glass substrate is integrated (FIG. 13A) via the integrated lens 8 and the holder 9 as shown in FIG. 11, or is attached to another glass substrate 10a. In addition, it can be integrated with the integrated lens 8 (FIG. 13B), or can be integrated with the integrated lens 8 together with the glass substrate 10b used for etching (FIG. 13C).
As described above, since the imaging lens 12, the coupling lens 3, and the diffractive optical element 4 are integrated, the positional relationship between the diffractive optical element 4, the coupling lens 3, and the pair of imaging lenses 12 of the stereo camera can be fixed. The pattern illumination does not cause a positional shift or a rotational shift due to vibration or a change with time. Thereby, ranging with high reliability can be realized.
As described above, since the pattern illumination device shown in FIG. 1 and the stereo camera shown in FIG. 3 are integrated, miniaturization can be realized, and at the same time, members constituting the pattern illumination device and the stereo camera are configured. Therefore, it is easy to detect misalignment between members and to easily correct the misalignment, and thus a highly reliable distance measuring device can be realized, and stable distance measurement can be performed against changes with time and vibration.

DESCRIPTION OF SYMBOLS 1 Pattern illumination apparatus, 2 Semiconductor laser light source, 3 Coupling lens, 4 Diffractive optical element, 5 Diffraction pattern light, 5A Diffraction pattern light, 5B Diffraction pattern light, 6a Temperature control function part, 6b APC function part, 70th order diffracted light , 7L imaging region, 7L 0th order diffracted light spot image, 7R 0th order diffracted light spot image, 8 lens array, 8 integral lens, 11 lens array, 12a imaging lens, 12b imaging lens, 13a optical axis, 13b optical axis, 14 imaging Element, 14a Wafer, 15a Imaging region, 15b Imaging region, 20 Stereo camera device, 30 Distance measuring device 30a Case, 31 Mirror, 40 Parallax calculation unit, 101 Measurement object, 102a Camera, 102b Camera, 103a Lens, 103b Lens 104a Measurement object image, 104b Measurement pair Object-image, 104c corresponding points, 105a two-dimensional sensor, 106 stereo camera device

JP 2001-147110 A

Claims (5)

A light source that emits illumination light for irradiating the subject;
A diffractive optical element that irradiates the subject with diffraction pattern light generated by diffracting the illumination light; and
A plurality of imaging lenses that image the diffraction pattern light reflected by the subject;
A plurality of imaging means for imaging a plurality of images related to the subject based on the diffraction pattern light imaged by the imaging lenses;
Ranging means for calculating a distance from the subject from parallax information between the plurality of images;
With
The diffractive optical element is
The diffraction pattern light is arranged at an angle that is disposed between the optical axes of the plurality of imaging lenses, and an irradiation area of the diffraction pattern light includes an area where the parallax information can be acquired via the plurality of imaging lenses. A distance measuring device capable of emitting light. The distance measuring device according to claim 1,
The diffractive optical element is disposed at the center position of the optical axis of the plurality of imaging lenses,
A detecting unit configured to detect a deviation in an emission angle of the diffraction pattern light based on a parallax position of a spot image of the 0th-order diffracted light included in the diffraction pattern light in the images acquired by the plurality of imaging units; A distance measuring device characterized by that. The distance measuring device according to claim 2,
The diffractive optical element diffracts the irradiation light so that the spot of the 0th-order diffracted light is larger in size or light intensity than other diffracted light spots. . The distance measuring device according to claim 1 or 2,
An optical means disposed on the near side of the diffractive optical element in the optical path of the illumination light emitted from the light source, and converting the illumination light into parallel light;
The distance measuring apparatus, wherein the optical means is formed integrally with the plurality of imaging lenses. The distance measuring device according to claim 1 or 2,
An optical means disposed on the near side of the diffractive optical element in the optical path of the illumination light emitted from the light source, and converting the illumination light into parallel light;
The diffractive optical element is formed integrally with the optical means or the plurality of imaging lenses.

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