JP2003050112A - Three-dimensional shape input device and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional shape input device realizing a phase shift method, using a relatively simple constitution. SOLUTION: To a projector 10, a plurality of light sources 31 to 34 placed with a specific interval in the direction (Z-direction) parallel to one main axis are provided. Also, a mask plate 41, for converting the light from each of the light sources 31 to 34 into a striped pattern with different intensity distribution periodically along the main axis, is provided apart from the light sources at specified distances. By letting each of the light sources 31 to 34 emit light in turn, the phases of the striped pattern projected to the object are constituted so as to be shifted for specific values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring a three-dimensional shape of an object by a pattern projection method.

[0002]

2. Description of the Related Art Conventionally, a projection device projects a striped pattern on an object, a shooting device photographs the striped pattern projected on the object, and the distortion of the striped pattern is analyzed to analyze the object. A device for measuring a three-dimensional shape is known. A method of analyzing a three-dimensional shape of an object by analyzing such a striped pattern is generally called a stripe analysis method.

In the fringe analysis method, it is required to accurately detect the position of each line forming the projected fringe pattern in order to specify a highly accurate three-dimensional shape. On the other hand, when there is a pattern on the surface of the object and the light reflectance is uneven, the stripe pattern projected from the projection device has uneven illuminance, or non-uniform ambient light is present on the object surface. When there is an influence of disturbance such as when the object is illuminated, it becomes difficult to accurately detect the position of each line of the striped pattern from the image taken by the imaging device, and the three-dimensional shape of the object Cannot be obtained with high accuracy.

Therefore, a phase shift method has been proposed in the past, in which the photographic device projects three or four images while phase-shifting the striped pattern projected on the object by ⅓ to ¼ wavelength. By taking a picture of the image and detecting the relative change in the brightness of each pixel between those images, the effect of disturbance such as the unevenness of the reflectance described above is eliminated,
It is possible to obtain the position of each line with relatively high accuracy.

FIG. 8 is a diagram showing a three-dimensional shape input device 100 to which a conventional phase shift method is applied. As shown in FIG. 8, the conventional three-dimensional shape input device 100 includes a projection device 110.
The projection device 110 is provided with a light source 111, a mask plate 112, and a drive unit 113. A mask having a striped pattern in which the light transmittance changes periodically is formed on the mask plate 112.
The light from 11 is guided to the object 9 through the mask plate 112. Therefore, the striped pattern 101 formed on the mask plate 112 is projected on the surface of the object 9, and the imaging device 1
The striped pattern is photographed by 20.

In the projection apparatus 110, the driving unit 113 drives the mask plate 112 along the shift direction 119 to make the phase of the striped pattern projected on the object 9 1/3 to 1/4. It is configured to shift by wavelength. Further, the image capturing device 120 is configured to capture an image of an object in each shift state and obtain the position of each line forming the striped pattern 101.

[0007]

By the way, in the case of the conventional three-dimensional shape input device 100, it is required to increase the positioning accuracy and reproducibility when driving the mask plate 112, but a simple method and configuration. It is difficult to improve the positioning accuracy and reproducibility. Therefore, in order to realize a driving mechanism that positions the mask plate 112 with high accuracy, there is a problem that a costly structure must be adopted.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a three-dimensional shape input device capable of realizing the phase shift method with a relatively simple structure. .

[0009]

In order to achieve the above object, the invention described in claim 1 is a projection device for projecting a periodic striped pattern on an object, and a projection device for projecting on the object. A three-dimensional shape input device comprising: a photographing device for photographing an image of the striped pattern, wherein the projection device comprises:
A plurality of light sources installed at a predetermined interval with respect to a direction parallel to one main axis, and installed at a predetermined distance from the plurality of light sources, and the light from each of the light sources is periodically along the main axis. Striped pattern generation means for converting into a striped pattern having a different light intensity distribution.

According to a second aspect of the present invention, in the three-dimensional shape input device according to the first aspect, the striped pattern generating means has a striped pattern in which light transmittance changes periodically along the main axis. It is characterized by being a mask plate having a pattern.

The invention according to claim 3 is the invention according to claim 1 or 2.
The three-dimensional shape input device according to claim 1, further comprising light source control means for shifting the phase of the striped pattern projected onto the object by a predetermined value by sequentially causing the plurality of light sources to emit light. Is characterized by.

According to a fourth aspect of the present invention, in the three-dimensional shape input device according to the third aspect, the photographing device projects on the object in each light emission state when the plurality of light sources are sequentially emitted. Is configured to capture an image of the striped pattern, and detects a relative change in luminance between the captured images obtained in each light emission state, and distorts the striped pattern according to the relative change. It further comprises a calculating means for obtaining the position and the amount of.

The invention according to a fifth aspect is the first to the fourth aspects.
In the three-dimensional shape input device according to any one of items 1 to 3, the predetermined distance d in which the plurality of light sources are installed is n, where the number of the plurality of light sources is n, and the periodic light generated in the striped pattern generation means is generated. The period along the main axis is λ, the distance between the plurality of light sources and the striped pattern generating means is S0,
Further, when an average distance from the striped pattern generating means to the object is S1, d = {λ · (S0 + S
1)} / (n · S1) is set as the interval.

According to a sixth aspect of the present invention, there is provided a projection device for measuring a three-dimensional shape of an object, comprising a plurality of light sources installed at predetermined intervals in a direction parallel to one main axis, and the plurality of light sources. And a striped pattern generating means for converting the light from each of the light sources into a striped pattern having different intensity distributions of light periodically along the main axis. ing.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a three-dimensional shape input device 1 according to an embodiment of the present invention. As shown in Figure 1,
The three-dimensional shape input device 1 includes a projection device 10 and a photographing device 20. In FIG. 1, X, Y, and
The three axes of Z are shown.

First, the projection device 10 will be described. The projection device 10 is a device that projects a periodic striped pattern on an object, and includes a plurality of (four in this embodiment) light sources 31, 32, 33, 34 that generate projection light, and each light source 31. The light source control unit 15 and the striped pattern generation unit 4 that converts the light from the light sources 34 to 34 into striped patterns. The projection device 10 projects a striped pattern that periodically changes in the Z direction onto an object arranged facing the projection device 10, and each line that forms the striped pattern is The line is parallel to the X direction.

Each of the light sources 31 to 34 is composed of, for example, a white light source or the like, and the light emitted from each of the light sources 31 to 34 passes through the striped pattern generating section 4 and is applied to the object. Each of the light sources 31 to 34 is fixed so as to have a predetermined interval in a direction parallel to the main axis (that is, the Z direction) when an axis parallel to the Z axis is the main axis. Moreover, the optical axes of the projection lights emitted from the respective light sources 31 to 34 are installed so as to be substantially parallel to each other.

The striped pattern generation unit 4 includes a plurality of light sources 31.
From 34 to 34 along the optical axis direction (Y direction), the light from each of the light sources 31 to 34 is converted into a striped pattern in which the light intensity distribution is periodically different along the main axis. To do. In this embodiment, the striped pattern generation unit 4
Is constituted by a mask plate 41 having a striped pattern whose light transmittance changes periodically along the main axis, and the mask plate 41 is fixed to the projection device 10. The mask plate 4
It is preferable that the first plate surface is installed so as to be substantially perpendicular to the optical axis of the projection light from each of the light sources 31 to 34.

Of the light arriving at the mask plate 41 from each of the light sources 31 to 34, the light incident on the high transmittance portion of the striped pattern formed on the mask plate 41 easily passes through the mask plate 41 and the transmittance is high. The light incident on the lower part of the mask plate 4
It is difficult to pass 1. Further, the light incident on the portion having the intermediate transmittance passes through the mask plate 41 according to the transmittance.

As a result, the light emitted from each of the light sources 31 to 34 is converted into light having a striped pattern by the mask plate 41, and the striped pattern is projected on the object.

The light source controller 15 sequentially selects one of the plurality of light sources 31 to 34 to emit light, and causes each of the light sources 31 to 34 to sequentially emit light. When the light source control unit 15 controls the light emitting state of each of the light sources 31 to 34, the light source control unit 15 supplies electric power for light emission to one light source to be emitted, and also to the photographing device 20. It is configured to instruct the shooting timing. As a result, the photographing device 20 can perform the photographing operation according to the light emission of each of the light sources 31 to 34.

The projection apparatus 10 is constructed as described above, and the plurality of light sources 31 to 34 individually emit light, so that the phase of the striped pattern projected on the object in each light emission state is 1/4 wavelength. It is configured to shift by one.

FIG. 2 is a diagram showing an example of a striped pattern projected by the projection device 10. As shown in FIG.
Of the projection light from the light source 31, the light ray L1 passing through the point A0 having a high transmittance in the central portion of the mask plate 41 is projected onto the point B1 on the surface of the object 9. As a result, the light source 31
When is emitted, a striped pattern P1 in which a bright portion and a dark portion are periodically repeated is formed on the surface of the object 9.

Of the projection light from the light source 32, the light ray L2 passing through the point A0 on the mask plate 41 is projected on the point B2 on the surface of the object 9. Therefore, when the light source 32 emits light, the striped pattern P2 is formed on the surface of the target object 9. The striped pattern P2 is in a state in which the phase is shifted by a quarter wavelength as compared with the striped pattern P1 when the light source 31 emits light.

Of the projection light from the light source 33, the light ray L3 passing through the point A0 on the mask plate 41 is projected on the point B3 on the surface of the object 9. Therefore, when the light source 33 emits light, the striped pattern P3 is formed on the surface of the target object 9. This striped pattern P3 is in a state in which the phase is shifted by a quarter wavelength as compared with the striped pattern P2 when the light source 32 emits light.

Further, of the projection light from the light source 34, the light ray L4 passing through the point A0 of the mask plate 41 is projected onto the point B4 on the surface of the object 9. Therefore, when the light source 34 emits light, the striped pattern P4 is formed on the surface of the target object 9. This striped pattern P4 is in a state in which the phase is shifted by a quarter wavelength as compared with the striped pattern P3 when the light source 33 emits light.

Therefore, by causing the projection device 10 to sequentially cause the plurality of light sources 31 to 34 to emit light, and for the striped patterns P1 to P4 projected on the object 9 in each light emitting state to be sequentially captured by the image capturing device 20, It is possible to capture four images that are phase-shifted by 1/4 wavelength and eliminate the influence of disturbance such as unevenness of reflectance on the surface of the object, and compare the position of each line forming the striped pattern. It becomes possible to obtain with high accuracy.

Furthermore, since it becomes possible to obtain the position of each line forming the striped pattern with relatively high accuracy, the striped pattern can be formed as compared with the case of the usual striped analysis method without phase shift. Each of the constituent lines can be made thin, which makes it possible to increase the density of the striped pattern.

Next, the photographing device 20 will be described. The image capturing device 20 is a device that captures an image of a striped pattern projected on an object, and projects the image about the main axis so that distortion of the striped pattern projected on the object can be captured well. It is installed at a predetermined distance from the device 10.

The photographing device 20 includes photographing lenses 21 and C for guiding an image of a striped pattern projected on an object to an image pickup element 22.
The image pickup device 22 configured by a CD area sensor or the like, the memory 23 that stores the image data of each image obtained from the image pickup device 22, and the predetermined calculation based on the image data stored in the memory 23 The calculation unit 24 for obtaining the position and amount of the distortion of the circular pattern, and the image sensor 22 in synchronization with the light emission of each of the light sources 31 to 34 in the projection device 10.
It is configured by including a photographing control unit 25 for controlling the.

The photographing apparatus 20 is configured to photograph the image of the striped pattern projected on the object in each light emitting state when the projection apparatus 10 sequentially emits the plurality of light sources 31 to 34. The image data acquired in each light emission state is stored in the memory 23. And each light source 3
When all the images of the light emitting states of 1 to 34 are photographed, the calculation unit 24 reads all the image data stored in the memory 23, and the calculation based on the phase shift method for removing the influence of disturbance, That is, the position and amount of distortion of the striped pattern are obtained with high accuracy by performing a calculation to detect a relative change in luminance between corresponding pixels among the four images.

The position and amount of distortion of the striped pattern projected on the object, which is obtained by the arithmetic unit 24, is
External device (computer, etc.) connected to the photographing device 20
It is possible to derive the three-dimensional shape of the object by analyzing the position and amount of the distortion of the striped pattern on the basis of the principle of triangulation in an external device.

Next, the plurality of light sources 3 in the projection device 10
The arrangement of 1 to 34 will be described. FIG. 3 and FIG. 4 are views showing the arrangement state of the light sources 31 to 34 with respect to the mask plate 41. FIG. 3 shows the case where the size of each light source 31 to 34 is relatively small, and FIG. Indicates a relatively large value.

As described above, in the plurality of light sources 31 to 34 in the projection apparatus 10, the main axis direction (direction in which the maximum transmittance portion 41a and the minimum transmittance portion 41b of the mask plate 41 are periodically repeated ( That is, they are fixed so as to have a predetermined interval in the Z direction). At this time, the light source 3
1 and the light source 32 are arranged at an interval d1, the light source 32 and the light source 33 are arranged at an interval d2, and the light source 33 and the light source 34 are arranged at an interval d3. The intervals d1, d2, d
3 is set to an interval in which the phase of the striped pattern on the surface of the object 9 changes by ¼ wavelength when the light sources 31 to 34 are individually and sequentially turned on.

Here, when the size of each of the light sources 31 to 34 is relatively small with respect to the installation intervals d1, d2 and d3, as shown in FIG. 3, a plurality of light sources 31 to 34 are arranged in a line along the main axis. Can be placed at.

On the other hand, when the size of each of the light sources 31 to 34 is relatively large with respect to the installation intervals d1, d2 and d3, the plurality of light sources 31 to 34 may be arranged in a line along the main axis. Have difficulty. Therefore, as shown in FIG.
It is also possible to set a plurality of arranging positions of the plurality of light sources 31 to 34 along the X direction and to arrange the arranging positions of the adjacent light sources along the X direction at different positions. Even in this case, if the installation intervals in the direction along the main axis are the predetermined intervals d1, d2, d3 as in the case of FIG. 3,
It is possible to shift the phase of the striped pattern projected on the object 9 by ¼ wavelength when each of the light sources 31 to 34 sequentially emits light.

In the three-dimensional shape input device 1 of this embodiment, four light sources 31 to 34 are provided, and the respective light sources 31 to 34 are sequentially turned on to shift the phase by 1/4 wavelength. Although it is configured to measure the three-dimensional shape by applying the shift method, in order to apply the phase shift method, for example, the phase may be shifted by ⅓ wavelength. The number may be three. Then, when the three light sources are sequentially emitted, the object 9
The three light sources may be installed at predetermined intervals so that the periodic phase of the striped pattern projected on is shifted by ⅓ wavelength.

Further, in order to obtain the position and amount of distortion of the striped pattern with higher accuracy by applying the phase shift method, the number of divisions of the striped pattern for one wavelength may be increased. For example, the more the number of light sources is increased to 5, 6, ..., The more detailed the phase shift can be realized, whereby the position of each line can be specified with higher accuracy. It becomes possible to do it.

That is, the number of light sources is not limited to the above-mentioned four, but may be any number of three or more.

Next, the installation interval of each light source when n light sources are provided (where n is an integer of 3 or more) will be examined.

FIG. 5 shows the four light sources 3 in the projector 10.
It is a figure which shows the example in which 1-34 were arrange | positioned. As shown in FIG. 5, the period (wavelength) of the periodic change in the transmittance of the striped pattern formed on the mask plate 41 is λ, the distance from the light sources 31 to 34 to the mask plate 41 is S0, and the mask plate 41 is The distance from to the surface of the object 9 is S1. However, since the surface of the target object 9 actually has three-dimensional unevenness, the distance S1 from the mask plate 41 to the surface of the target object 9 is a surface representing the target object 9 from the mask plate 41, for example, unevenness. Is determined with reference to the forefront surface or the rearmost surface in the depth range of, the surface located in the middle of the unevenness, or the average surface of the unevenness. further,
In FIG. 5, the distance between the light sources 31 to 34 in the main axis direction is d (= d1 = d2 = d3).

In the case where the phase shift is performed by ¼ wavelength and four images are photographed, FIG.
Consider a case where the fifth virtual light source 30 is installed at a distance d in the main axis direction with respect to the light source 31, as shown in FIG. In this case, the striped pattern projected by the fifth virtual light source 30 returns to the same phase as the striped pattern projected by the light source 34. That is, the light ray L0 incident from the virtual light source 30 to the point A1 on the mask plate 41 adjacent to the point A0 having the maximum transmittance is the same as the light ray L4 passing from the light source 34 to the point A0 on the surface of the object 9. It is projected on the point B4.

When the virtual light source 30 is included, each light source 3
There are four intervals d between 0 and 34, and the interval between the light source 34 and the virtual light source 30 is (4 · d). This
In general, when there are n light sources, the distance d between each light source is n, and the distance between all light sources including the virtual light source is (n · d).

Therefore, referring to FIG. 5, geometrically, S1: λ = (S0 + S1) :( n · d) (Equation 1) is established. When the distance d between the light sources is calculated from the above formula 1, d = {λ · (S0 + S1)} / (n · S1) (Formula 2) is obtained.

Therefore, when n light sources are installed in the projection device 10 as a plurality of light sources, the distances along the main axis of the respective light sources are calculated by the distance d calculated by the above-mentioned formula 2.
If set to, it is possible to project a striped pattern, which is phase-shifted by 1 / n wavelength when each light source is sequentially emitted, onto the target object 9.

As described above, the projection device 10 of the three-dimensional shape input device 1 described in this embodiment has the mask plate 41.
It is configured to realize the phase shift method by arranging a plurality of light sources at a predetermined interval and sequentially emitting light from each light source, instead of moving the light source to realize the phase shift method. Therefore, it is not necessary to arrange a complicated drive mechanism for the projection device 10, and it is possible to project a striped pattern having high reproducibility even when the striped pattern is repeatedly projected on the object 9. is there. That is, according to the three-dimensional shape input device 1, the phase shift method is realized with a relatively simple configuration, and the three-dimensional shape of the object 9 can be measured with high accuracy.

If a silver salt film or the like is used as the mask plate 41, it is possible to form a precise projection pattern on the mask plate 41. In that case, a fine and smooth striped pattern is formed on the surface of the object. It is possible to project.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above description.

First, in the above description, an example in which the striped pattern generating section 4 is constituted by the mask plate 41 having a striped pattern whose light transmittance changes periodically along the main axis has been described. It is not limited.

FIG. 6 is a diagram showing an example in which the lens array 42 is used as the striped pattern generation section 4. As shown in FIG. 6, a lens array 42 such as a lenticular lens may be installed from a plurality of light sources 31 to 34 at predetermined intervals along the optical axis. Even with such a configuration, the striped pattern is projected onto the object 9 by the action of each lens unit that configures the lens array 42, and each light source 31 to 34.
It is possible to shift the phase of the striped pattern projected on the object 9 by sequentially emitting light.

FIG. 7 is a diagram showing an example in which the prism 43 is used as the striped pattern generation section 4. As shown in FIG. 7, a prismatic prism 43 having a single flat surface on the incident side and a plurality of flat surfaces on the emitting side that are not parallel to each other is provided from a plurality of light sources 31 to 34 along the optical axis. You may make it install at intervals. Even with this structure, the stripe pattern is projected on the object 9 by the action of the prism 43, and the stripe patterns of the stripe pattern projected on the object 9 are sequentially emitted by the light sources 31 to 34. It is possible to shift the phase.

Next, the projection device 10 and the photographing device 20 may be configured to be separable. For example, the photographing device 20
It is also possible to realize the projection device 10 as an external attachment device by configuring the above with a digital camera or the like.

[0054]

As described above, according to the invention described in claims 1 and 6, a plurality of light sources are arranged at a predetermined interval in the direction parallel to one main axis, and further, the plurality of light sources. Since the striped pattern generating means installed at a predetermined distance from is configured to convert the light from each light source into a striped pattern in which the light intensity distribution is periodically different along the main axis, It is possible to project a striped pattern that realizes the phase shift method with an extremely simple configuration.

According to the second aspect of the present invention, since the striped pattern generating means is a mask plate having a striped pattern in which the light transmittance changes periodically along the main axis, As a result, it is possible to excellently project a striped pattern in which the light intensity distribution changes periodically.

According to the third aspect of the invention, the phase of the striped pattern projected onto the object is shifted by a predetermined value by sequentially causing the plurality of light sources to emit light. Therefore, it is possible to realize a phase shift method with high reproducibility.

According to the fourth aspect of the present invention, the relative change in the luminance between the picked-up images obtained in each light emission state when a plurality of light sources are sequentially emitted is detected, and the relative change is detected. Since the position and the amount of distortion of the striped pattern are obtained accordingly, the position and the amount of distortion of the striped pattern can be obtained with high accuracy.

According to the fifth aspect of the present invention, it is possible to project a striped pattern that realizes the phase shift method with a relatively simple structure, regardless of the number of light sources.

[Brief description of drawings]

FIG. 1 is a diagram showing a three-dimensional shape input device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a striped pattern projected by a projection device.

FIG. 3 is a diagram showing an example of an arrangement state of light sources with respect to a mask plate.

FIG. 4 is a diagram showing another example of arrangement of light sources on a mask plate.

FIG. 5 is a diagram for explaining an arrangement interval of a plurality of light sources.

FIG. 6 is a diagram showing an example in which a lens array is used as a striped pattern generation unit.

FIG. 7 is a diagram showing an example in which a prism is used as a striped pattern generation unit.

FIG. 8 is a diagram showing a three-dimensional shape input device to which a conventional phase shift method is applied.

[Explanation of symbols]

1 3D shape input device 4 Striped pattern generation unit (striped pattern generation means) 10 Projector 15 Light source control unit (light source control means) 20 Imaging device 22 Image sensor 23 memory 24 Calculation unit (calculation means) 25 Shooting control section 31-34 light source 41 mask plate 42 lens array 43 prism d, d1 to d3 light source arrangement interval Z spindle direction

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tetsuya Katagiri             2-3-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Osaka International Building Minolta Co., Ltd. F term (reference) 2F065 AA04 AA53 DD02 FF07 FF09                       GG02 GG13 GG24 HH05 HH13                       JJ03 JJ08 JJ26 LL28 NN00                       QQ24 QQ31

Claims (6)

[Claims] 1. A three-dimensional shape input device comprising: a projection device for projecting a periodic striped pattern on an object; and a photographing device for photographing an image of the striped pattern projected on the object. Wherein the projection device is installed with a plurality of light sources installed at a predetermined interval in a direction parallel to one main axis, and installed with a predetermined distance from the plurality of light sources, and light from each of the light sources. A three-dimensional shape input device, comprising: a striped pattern generation unit that converts the light into a striped pattern having different light intensity distributions periodically along the main axis. 2. The three-dimensional shape input device according to claim 1, wherein the striped pattern generation means is a mask plate having a striped pattern whose light transmittance changes periodically along the main axis. A three-dimensional shape input device characterized in that 3. The three-dimensional shape input device according to claim 1, wherein the phase of the striped pattern projected onto the object is set to a predetermined value by sequentially causing the plurality of light sources to emit light. A three-dimensional shape input device, further comprising a light source control means for shifting each by one. 4. The three-dimensional shape input device according to claim 3, wherein in each of the light emitting states when the plurality of light sources are sequentially emitted, the image capturing device is configured to project the striped pattern on the object. An arithmetic operation configured to capture an image, detecting a relative change in luminance between the captured images obtained in each light emission state, and obtaining the position and amount of distortion of the striped pattern according to the relative change. A three-dimensional shape input device further comprising means. 5. The three-dimensional shape input device according to claim 1, wherein the predetermined distance d in which the plurality of light sources are installed is the number of the plurality of light sources n, and the striped pattern. The period of the periodic light generated by the generating means along the main axis is λ, and the distance between the plurality of light sources and the striped pattern generating means is S.
0 and an average distance from the striped pattern generating means to the object is S1, the distance is set to be represented by d = {λ · (S0 + S1)} / (n · S1). A three-dimensional shape input device characterized in that 6. A projection device for measuring a three-dimensional shape of an object, comprising: a plurality of light sources installed at predetermined intervals in a direction parallel to one main axis; and a plurality of light sources separated from the plurality of light sources by a predetermined distance. And a striped pattern generation unit that converts the light from each of the light sources into a striped pattern having different intensity distributions of light periodically along the main axis.