JP2019028456A - Diffraction optical element, light irradiation device, light irradiation system and correction method of projection pattern - Google Patents

Abstract

To provide a diffraction optical element capable of easily correcting distortion caused by an imaging lens, a light irradiation device, a light irradiation system and a correction method of a projection pattern.SOLUTION: A diffraction optical element 10 is a diffraction optical element for shaping light and includes a diffraction grating that projects a first projection pattern 23 as a projection pattern projected by diffracting incident light to exit, and a position reference pattern 24 that is a projection pattern different from the first projection pattern 23, for specifying a position in the projection pattern.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a diffractive optical element, a light irradiation apparatus, a light irradiation system, and a projection pattern correction method.

  In recent years, applications of sensor systems have been expanded. There are various types of sensors, and various types of information are detected. As one of the means, there is a method in which light is emitted from a light source to an object and information is obtained from the reflected light. For example, a pattern authentication sensor, an infrared radar, etc. are examples.

  The light sources of these sensors are those having a wavelength distribution, brightness, spread, etc. according to the application. As the wavelength of light, a range from visible light to infrared light is often used. In particular, infrared rays are widely used because they are not easily affected by outside light, are invisible, and can slightly observe the inside of an object. As the type of light source, an LED light source, a laser light source, and the like are often used. For example, when detecting a distant place, a laser light source with a small light spread is preferably used, and when detecting a relatively close place, an LED light source is suitable for irradiating an area with a certain extent. Used for.

By the way, the size, shape, etc. of the target irradiation region do not necessarily match the spread (profile) of the light from the light source, and it is necessary to shape the light with a diffusion plate, a lens, a shielding plate, etc. is there. As means for shaping the light, a diffractive optical element (DOE) can be cited. This is an application of the diffraction phenomenon when light passes through a place where materials having different refractive indexes are arranged with periodicity. A DOE is basically designed for light of a single wavelength, but theoretically it is possible to shape the light into almost any shape. Also, with DOE, it is possible to control the uniformity of the light distribution in the irradiation area. Such a characteristic of the DOE is advantageous in terms of high efficiency by suppressing irradiation to an unnecessary area, miniaturization of the apparatus by reducing the number of light sources, and the like.
The DOE can be applied to both a parallel light source such as a laser and a diffuse light source such as an LED, and can be applied to a wide range of wavelengths from ultraviolet light to visible light and infrared light.
Japanese Patent Application Laid-Open No. H10-228561 discloses a technique of using a diffraction grating by irradiating an optical mark.

  In a sensor system that shapes and irradiates light using DOE, for example, a projected pattern may be photographed using a camera and used for various types of detection and analysis. In such a case, distortion inherent to the camera's photographic lens may occur in the photographic result. Since this distortion distorts the original projected image, it may need to be corrected. Conventionally, taking into account the amount of distortion caused by the aberration of the taking lens of the camera, the DOE is sometimes configured so as to project the projection image with distortion in the opposite direction in advance. However, in the conventional response method, if the photographic lens changes, it is necessary to recreate the DOE as an object corresponding to it, which is inefficient.

JP 2012-73822 A

  An object of the present invention is to provide a diffractive optical element, a light irradiation apparatus, a light irradiation system, and a projection pattern correction method that can easily correct distortion caused by a photographing lens.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.

  The first invention is a diffractive optical element (10) for shaping light, and as a projection pattern projected by diffracting and emitting incident light, the first projection pattern (23) and the first The diffractive optical element (10) includes a diffraction grating that projects a position reference pattern (24) that specifies a position in the projection pattern, which is a projection pattern different from the one projection pattern (23).

  According to a second invention, in the diffractive optical element (10) according to the first invention, the diffraction grating is configured such that the luminance of the position reference pattern (24) is lower than the luminance of the first projection pattern (23). The diffractive optical element (10) is characterized by comprising:

  According to a third invention, in the diffractive optical element (10) according to the second invention, the luminance of the position reference pattern (24) is 1/10 or more of the luminance of the first projection pattern (23). The diffractive optical element (10) is characterized in that the diffraction grating is configured to be 3 or less.

  The fourth invention is a light source unit (20) and a diffractive optical element that is arranged at a position irradiated with light from the light source unit (20), and shapes and emits light from the light source unit (20). 10), and the projection pattern projected from the diffractive optical element (10) is a projection pattern different from the first projection pattern (23) and the first projection pattern (23). The light irradiation device (1) includes a position reference pattern (24) for specifying a position in the projection pattern.

  5th invention is the light irradiation apparatus (1) as described in 4th invention, The said position reference pattern (24) specifies the position of at least 3 places, The light irradiation apparatus (1) characterized by the above-mentioned. It is.

  A sixth invention is the light irradiation apparatus (1) according to the fourth invention or the fifth invention, wherein the position reference pattern (24) is around the projection range of the first projection pattern (23). It is arrange | positioning, It is a light irradiation apparatus (1) characterized by the above-mentioned.

  According to a seventh aspect, in the light irradiation device (1) according to the sixth aspect, the position reference pattern (24) is arranged along the outer shape of the projection range of the first projection pattern (23). It is the light irradiation apparatus (1) characterized by these.

  According to an eighth aspect of the present invention, in the light irradiation apparatus (1) according to any one of the fourth to seventh aspects, the luminance of the position reference pattern (24) is the same as that of the first projection pattern (23). The light irradiation device (1) is characterized by being lower than luminance.

  According to a ninth aspect, in the light irradiation apparatus (1) according to the eighth aspect, the luminance of the position reference pattern (24) is 1/10 or more of the luminance of the first projection pattern (23). It is a light irradiation apparatus (1) characterized by being 3 or less.

  A tenth aspect of the invention is a diffractive optical element (20) and a diffractive optical element (20) disposed at a position where light from the light source unit (20) is irradiated, and shaping and emitting light from the light source unit (20). 10) and a camera (30) for acquiring an image of a projection pattern projected and projected from the diffractive optical element (10), and a projection pattern projected and projected from the diffractive optical element (10) Includes a first projection pattern (23) and a position reference pattern (24) that is a projection pattern different from the first projection pattern (23) and specifies a position in the projection pattern, and A correction processing unit (40) for analyzing an image of the projection pattern acquired by the camera (30) and correcting distortion of the projection pattern caused by the camera (30) based on the position of the position reference pattern (24); The Is obtain an optical illumination system (2).

  An eleventh invention is characterized in that, in the light irradiation system (2) according to the tenth invention, the luminance of the position reference pattern (24) is lower than the luminance of the first projection pattern (23). This is a light irradiation system (2).

  According to a twelfth aspect, in the light irradiation system (2) according to the eleventh aspect, the luminance of the position reference pattern (24) is 1/10 or more of the luminance of the first projection pattern (23). It is a light irradiation system (2) characterized by being 3 or less.

  The thirteenth aspect of the invention corrects distortion of the projection pattern when the projection pattern projected by the diffractive optical element (10) that shapes and emits the light from the light source unit (20) is further photographed by the camera (30). A method for correcting a projection pattern, wherein the diffractive optical element (10) is a projection pattern different from the first projection pattern (23) and the first projection pattern (23). A projection pattern including a position reference pattern (24) for specifying a position is projected, the camera (30) images the projection pattern, and a correction processing unit (40) images the camera (30). Projection pattern correction method for correcting distortion of a projection pattern image generated by the camera (30) based on the position of the position reference pattern (24) included in the projection pattern image A.

  According to a fourteenth aspect of the present invention, in the projection pattern correction method according to the thirteenth aspect of the present invention, the luminance of the position reference pattern (24) is lower than the luminance of the first projection pattern (23). This is a projection pattern correction method.

  A fifteenth aspect of the invention is the projection pattern correction method according to the fourteenth aspect of the invention, wherein the luminance of the position reference pattern (24) is 1/10 or more of the luminance of the first projection pattern (23). The projection pattern correction method is characterized by the following.

  According to the present invention, it is possible to provide a diffractive optical element, a light irradiation apparatus, a light irradiation system, and a projection pattern correction method that can easily correct distortion caused by a photographing lens.

It is a top view which shows embodiment of the diffractive optical element by this invention. It is a perspective view which shows an example of the partial periodic structure in the example of the diffractive optical element of FIG. It is sectional drawing which showed the diffractive optical element typically. It is a figure explaining a diffractive optical element. It is a figure explaining the outline | summary of the light irradiation system 2 provided with the light irradiation apparatus 1. FIG. FIG. 4 is an enlarged view showing an example of projection of a first projection pattern 23 and a position reference pattern 24 onto a screen 500. It is the figure which expanded the position reference pattern 24 shown in FIG. FIG. 4 is an enlarged view showing an example of a captured image including distortion as a result of capturing the first projection pattern 23 and the position reference pattern 24 projected onto the screen 500 by the camera 30; It is an arrangement example of the position reference pattern 24 when the first projection pattern 23 is rectangular. It is an arrangement example of the position reference pattern 24 when the shape of the first projection pattern 23 before being photographed by the camera 30 is a pincushion type. It is an arrangement example of the position reference pattern 24 when the shape of the first projection pattern 23 before being photographed by the camera 30 is a trapezoidal shape. It is an example of arrangement | positioning of the position reference pattern 24 in case the shape of the 1st projection pattern 23 before image | photographing with the camera 30 is circular shape. It is a figure which shows the example of the shape of the position reference pattern 24 based on a triangle. It is a figure which shows the example of the shape of the position reference pattern 24 based on the circle. It is a figure which shows the example of the shape of the position reference pattern 24 based on the square which rounded the corner. It is a figure which shows the example of a shape of the position reference pattern 24 based on a rectangle. It is a figure which shows the example of a shape of the position reference pattern 24 based on a cross. It is a figure which expands and shows the example of a projection to the screen 500 of the 1st projection pattern 23 and the position reference pattern 24 by the diffractive optical element of 2nd Embodiment.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a plan view showing a first embodiment of a diffractive optical element according to the present invention.
FIG. 2 is a perspective view showing an example of a partial periodic structure in the example of the diffractive optical element of FIG.
FIG. 3 is a cross-sectional view schematically showing the diffractive optical element.
FIG. 4 is a diagram illustrating a diffractive optical element.
In addition, each figure shown below including FIG. 1 is the figure shown typically, and the magnitude | size and shape of each part are exaggerated suitably for easy understanding.
In the following description, specific numerical values, shapes, materials, and the like are shown and described, but these can be changed as appropriate.

  As used in the present invention, the shape and geometric conditions, and terms specifying the degree thereof, for example, terms such as “parallel”, “orthogonal”, “same”, length and angle values, etc. Without being limited to a strict meaning, it should be interpreted to include a range where a similar function can be expected.

In the present invention, “shaping the light” means controlling the light traveling direction so that the shape of the light projected on the target object or target region (irradiation region) becomes an arbitrary shape. Say. For example, as shown in the example of FIG. 4, a light source unit 20 is prepared that emits light 21 (FIG. 4B) in which the irradiation region 22 has a circular shape when directly projected onto a planar screen 500. By transmitting this light 21 through the diffractive optical element 10 of the present invention, the projection pattern (first projection pattern) 23 can be formed into a square (FIG. 4A), a rectangle, a circle (not shown), or the like. Making the shape of or irradiating the illuminance distribution so as to be the target distribution is called “shaping light”.
Note that light that can be irradiated in a molded state by combining the light source unit 20 and the diffractive optical element 10 of the present embodiment, which is disposed at a position where at least one light emitted from the light source unit 20 passes. It can be set as an irradiation apparatus.
In the present invention, the term “transparent” refers to a material that transmits at least light having a wavelength to be used. For example, even if it does not transmit visible light, as long as it transmits infrared light, it is handled as transparent when used for infrared applications.

The diffractive optical element 10 of this embodiment is a diffractive optical element (DOE) that shapes light. The diffractive optical element 10 is designed so as to spread light into a cross shape, a rectangular shape, or the like with respect to light from the light source unit 20 that emits light having a wavelength of 850 nm.
The diffractive optical element 10 of the present embodiment has different depths at positions A, B, C, and D shown in FIG. That is, the diffractive optical element 10 has a multi-stage shape with four levels of height. The diffractive optical element 10 usually has a plurality of regions having different periodic structures (partial periodic structures: for example, E and F regions in FIG. 1). In FIG. 3, a part of the partial periodic structure is extracted and shown.
The diffractive optical element 10 has a complicated shape as shown in FIG. 2, but when schematically illustrated schematically, a plurality of convex portions 11a are arranged side by side in a cross-sectional shape as shown in FIG. The high refractive index portion 11 is provided.

The high refractive index portion 11 can be manufactured by processing the shape of quartz (SiO ₂ , synthetic quartz) by an etching process, for example. Alternatively, the high refractive index portion 11 may be produced by taking a mold from a material obtained by processing quartz and forming a forming die and curing the ionizing radiation curable resin composition using the forming die. Various methods for producing such a periodic structure using an ionizing radiation curable resin composition are known, and the high refractive index portion 11 of the diffractive optical element 10 uses these known methods. And can be appropriately manufactured.

  In addition, air is present in the upper portion of FIG. 3 including the recess 12 formed between the protrusions 11 a and the space 13 near the top of the protrusion 11 a, and the refractive index is higher than that of the high refractive index portion 11. The low refractive index portion 14 is low. A diffraction layer 15 having a function of shaping light is constituted by a periodic structure in which the high refractive index portions 11 and the low refractive index portions 14 are alternately arranged.

  The convex portion 11a has a multi-stage shape including four step portions having different heights on one side (left side in FIG. 3) of the side surface shape. Specifically, the convex portion 11a includes the most protruding level 1 step portion 11a-1, the level 2 step portion 11a-2 that is one step lower than the level 1 step portion 11a-1, and the level 2 step portion 11a-2. Furthermore, it has a level 3 step portion 11a-3 that is one step lower and a level 4 step portion 11a-4 that is one step lower than the level 3 step portion 11a-3 on one side surface side. Moreover, the other side (right side in FIG. 3) of the side surface shape of the convex portion 11a is a side wall portion 11b that is connected in a straight line from the level 1 step portion 11a-1 to the level 4 step portion 11a-4.

FIG. 5 is a diagram illustrating an outline of the light irradiation system 2 including the light irradiation device 1.
The light irradiation system 2 of this embodiment includes a light irradiation device 1, a camera 30, and a correction processing unit 40.
The light irradiation device 1 includes a diffractive optical element 10 and a light source unit 20.

The basic configuration of the diffractive optical element 10 is as described above. However, in the diffractive optical element 10 of the present embodiment, the diffraction grating of the diffraction layer 15 is designed and formed so as to project the position reference pattern 24 in addition to the first projection pattern 23.
FIG. 6 is an enlarged view showing an example of projection of the first projection pattern 23 and the position reference pattern 24 onto the screen 500.
In the example shown in FIG. 6, the first projection pattern 23 is a pattern in which a large number of fine random dots are projected onto a square area indicated by hatching, although the specific shape is not shown. Each position of this random dot is known. Therefore, how the first projection pattern 23 is projected, that is, how the position is changed, is captured and analyzed by the camera 30 described later, and solid detection and distance measurement are performed. It is possible.

The position reference pattern 24 is a projection pattern different from the first projection pattern, and is a pattern for specifying a position in the projection pattern. The specification of this position will be described later.
In the example shown in FIG. 6, the position reference pattern 24 is arranged around the first projection pattern 23 with a certain interval. More specifically, the position reference pattern 24 is arranged at a position corresponding to each of the four corners of the first projection pattern 23 and a position corresponding to the center position of each of the four sides of the first projection pattern 23. Yes. That is, the position reference patterns 24 are arranged in a total of eight locations.
By disposing the position reference pattern 24 around the first projection pattern 23, an accurate correction process can be performed without affecting the originally required first projection pattern 23. In particular, when the position reference pattern 24 is arranged along the outer shape of the projection range of the first projection pattern 23, more accurate correction processing can be performed. In addition, it is advantageous in terms of correction processing to provide a large number of position reference patterns 24. However, when a large number are provided, it is assumed that only the first projection pattern 23 is necessary for the original purpose. Therefore, when the position reference pattern 24 is in the way, the number of the position reference patterns 24 can be appropriately reduced. However, the position reference pattern 24 is preferably arranged so that at least three positions can be specified.

FIG. 7 is an enlarged view of the position reference pattern 24 shown in FIG.
In this example, the position reference pattern 24 includes two orthogonal straight lines 24 a and triangles 24 b provided at both ends of the straight line 24. When the two straight lines 24a are arranged in this way, the position can be easily identified at the intersection. Further, by providing the triangle 24b, if the captured image of the straight line 24 is unclear, a partial straight line connecting the vertices of the triangle can be generated by arithmetic processing, and the position can be specified.

  The design of the diffraction layer 15 capable of projecting the first projection pattern 23 and the position reference pattern 24 is, for example, GradingMOD (manufactured by Rsoft) using an exact coupling wave analysis (RCWA) algorithm, an iterative Fourier transform algorithm. It can be performed using various simulation tools such as Virtuallab (made by LightTrans) using (IFTA).

  Returning to FIG. 5, the light source unit 20 includes a light emitting element that irradiates light to the diffractive optical element 10. As the light source unit 20, for example, an LED or a laser light emitting element such as a VCSEL may be used. Further, the light emitted from the light source unit 20 may be infrared light, visible light, or any light that can be photographed by the camera 30.

  The camera 30 captures the projection pattern (the first projection pattern 23 and the position reference pattern 24) projected by the light irradiation device 1. The camera 30 is configured to be able to photograph light emitted from the light source unit 20. For example, when the light source unit 20 emits infrared light, the camera 30 is configured to capture infrared light.

The correction processing unit 40 analyzes the projection pattern image acquired by the camera 30 and corrects the distortion of the projection pattern generated by the camera 30 based on the position of the position reference pattern 24.
The camera 30 shoots a projection pattern using a shooting lens (not shown), but the captured image is distorted by the distortion of the lens. This distortion varies depending on the optical system of the lens.For example, the rectangle becomes barrel-shaped due to distortion that the center part swells, or conversely, the rectangle becomes pincushion type due to distortion that the center part shrinks. To do. There is also an aberration that combines a barrel type and a pincushion type. Basically, the distortion is small enough that the individual difference can be ignored if the optical system of the lens is the same. However, if the lens optical system is different, that is, if the lens has a different design, the degree of expression of distortion is greatly different. Therefore, when different types of cameras 30 are used, the image distortion caused by distortion changes.

  Conventionally, the diffractive optical element 10 has been designed and manufactured so that a projection pattern is photographed in an appropriate shape according to each optical system. For example, in the case of an optical system that is distorted into a pincushion type, the diffractive optical element 10 that can project a barrel-shaped projection pattern by an amount that is estimated in advance is produced. However, the production was performed by repeating a plurality of actual measurements and trial productions, which was very inefficient. Also, it has been difficult to obtain a captured image of a projection pattern that is completely free of distortion. Furthermore, even if the diffractive optical element 10 is manufactured with such difficulty, if the camera 30 is different, it is necessary to recreate the diffractive optical element 10 again in accordance with the distortion of the optical system. It was.

  Therefore, in the present embodiment, the position reference pattern 24 is used to accurately acquire the amount of distortion, and the correction processing unit 40 calculates the correction amount for the captured image based on the acquired amount of distortion. Then, the photographed image is corrected to generate a corrected image of the projection pattern without distortion.

FIG. 8 is an enlarged view showing an example of a photographed image including distortion as a result of photographing the first projection pattern 23 and the position reference pattern 24 projected onto the screen 500 by the camera 30.
In the example of the photographed image shown in FIG. 8, the image is distorted into a pincushion mold. The correction processing unit 40 acquires a captured image including this distortion, and calculates how much the position of the position reference pattern 24 is shifted from the original position, that is, how much the captured image is distorted. Then, based on the calculated distortion amount, a correction amount for correcting the captured image to image data correctly representing the positions of the first projection pattern 23 and the position reference pattern 24 projected on the screen 500, or correction Generate and get an expression. If the captured image is corrected according to the correction amount or the correction formula, the distortion generated by the camera 30 can be corrected correctly.

In addition, since it is assumed that the correction amount by the correction processing unit or the process of acquiring the correction formula does not change greatly due to individual differences of the cameras 30, the correction amount or The correction formula may be commonly used in the light irradiation device 1 having the same configuration.
Further, when the light irradiation device 1 of the present embodiment is diverted to a light irradiation system including another camera of a different model from the camera 30, a correction amount or a correction formula is once used with a new camera. After that, similarly to the above, the correction amount or the correction formula can be shared by the light irradiation apparatuses having the same configuration.

(Modification regarding arrangement of position reference pattern 24)
The arrangement of the position reference pattern 24 is not limited to the above-described example, and can be appropriately changed according to the outer shape of the first projection pattern 23.
FIG. 9 is an arrangement example of the position reference pattern 24 when the first projection pattern 23 has a rectangular shape.
FIG. 9B is the same arrangement as the above-described example, but, for example, as shown in FIG.

FIG. 10 is an arrangement example of the position reference pattern 24 when the shape of the first projection pattern 23 before being photographed by the camera 30 is a pincushion type.
FIG. 11 is an arrangement example of the position reference pattern 24 when the shape of the first projection pattern 23 before being photographed by the camera 30 is a trapezoidal shape.
FIG. 12 is an arrangement example of the position reference pattern 24 when the shape of the first projection pattern 23 before being photographed by the camera 30 is a circular shape.
As shown in FIG. 10A, FIG. 11A, and FIG. 12A, the position reference pattern 24 is arranged so as to have a rectangular shape regardless of the shape of the first projection pattern 23. Also good. Further, as shown in FIG. 10B, FIG. 11B, and FIG. 12B, the position reference pattern 24 may be arranged along the outer shape of the first projection pattern 23.

(Modification regarding the shape of the position reference pattern 24)
Further, regarding the shape of the position reference pattern 24, the above-described shape is considered to be the best form, but it may be a form as illustrated in the following drawings.
FIG. 13 is a diagram illustrating a shape example of the position reference pattern 24 based on a triangle.
FIG. 14 is a diagram showing a shape example of the position reference pattern 24 based on a circle.
FIG. 15 is a diagram showing a shape example of the position reference pattern 24 based on a quadrangle with rounded corners.
FIG. 16 is a diagram illustrating a shape example of the position reference pattern 24 based on a quadrangle.
As shown in FIGS. 13A, 14A, 15A, and 16A, the position reference pattern 24 may have a hollow shape.
As shown in FIGS. 13B, 14B, 15B, and 16B, the shape of the position reference pattern 24 may be a shape in which each shape is filled.
As shown in FIG. 13C, FIG. 14C, FIG. 15C, and FIG. It is good also as a shape provided with.

FIG. 17 is a diagram showing an example of the shape of the position reference pattern 24 based on cross characters.
As for the shape of the position reference pattern 24 based on the crossed characters, straight lines may be arranged at an angle of 45 ° as shown in FIG. 17A, or straight lines are arranged horizontally and vertically as shown in FIG. 17B. May be. Moreover, as shown in FIG.17 (c), it is good also as a shape where the center was outlined.

As described above, according to the present embodiment, the correction processing unit 40 changes the position of the position reference pattern 24 with respect to an image obtained by projecting the position reference pattern 24 together with the first projection pattern 23 and capturing the image with the camera 30. Based on the above, a correction amount or a correction formula is generated and acquired. Therefore, if the acquired correction amount or correction formula is used, then the correct image can be always corrected by the correction amount or correction formula, and the distortion aberration of the camera 30 can be removed.
In addition, since the amount of distortion can be accurately grasped by the position reference pattern 24, correction with high correction can be performed.

(Second Embodiment)
FIG. 18 is an enlarged view showing an example of projection of the first projection pattern 23 and the position reference pattern 24 onto the screen 500 by the diffractive optical element according to the second embodiment.
The second embodiment is a form in which the luminance of the first projection pattern 23 and the position reference pattern 24 is changed, and other parts are the same as those of the first embodiment. Therefore, the same reference numerals are given to the portions that perform the same functions as those in the first embodiment described above, and repeated descriptions are omitted as appropriate.

  In the first embodiment described above, as an easy-to-understand example, an example in which the first projection pattern 23 is a rectangular area formed in a relatively large area and is clearly different in shape from the position reference pattern 24 will be described. did. However, the first projection pattern 23 can take various forms depending on the application. For example, the first projection pattern 23 may be an aggregate of a large number of irradiation spots as shown in FIG. In such a case, it may be difficult to distinguish between the first projection pattern 23 and the position reference pattern 24. In particular, when the shape of the position reference pattern 24 is close to the shape of the first projection pattern 23 as shown in FIG.

Therefore, in the second embodiment, the luminance of the position reference pattern 24 is lower than the luminance of the first projection pattern 23, and the luminance difference in addition to the pattern shape is also different from that of the first reference pattern 24. This is used as a criterion for distinguishing and recognizing the projection pattern 23. Thereby, the precision which distinguishes and recognizes the position reference pattern 24 and the 1st projection pattern 23 can be raised, and misrecognition can be prevented.
Here, if the luminance of the position reference pattern 24 is lower than 1/10 of the luminance of the first projection pattern 23, it is difficult to detect and recognize the position reference pattern 24. If the luminance of the position reference pattern 24 exceeds 2/3 of the luminance of the first projection pattern 23, the difference between the luminance of the position reference pattern 24 and the luminance of the first projection pattern 23 becomes too small. It becomes difficult to distinguish by luminance difference. Therefore, it is desirable that the luminance of the position reference pattern 24 is 1/10 or more and 2/3 or less of the luminance of the first projection pattern 23.

  As described above, according to the second embodiment, the brightness of the position reference pattern 24 is lower than the brightness of the first projection pattern 23, and the brightness difference in addition to the shape of the pattern is also determined. The pattern 24 and the first projection pattern 23 are used as judgment criteria for distinguishing and recognizing. Therefore, the position reference pattern 24 and the first projection pattern 23 can be distinguished and recognized with high accuracy, and erroneous detection and recognition can be prevented.

(Deformation)
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the scope of the present invention.

(1) In the embodiment, the arrangement and shape of the position reference pattern 24 have been described with a plurality of specific examples. However, the arrangement and shape of the position reference pattern 24 can be changed as appropriate.

(2) In the embodiment, the position reference pattern 24 has been described with an example in which the position reference pattern 24 is arranged at a position away from the first projection pattern 23. For example, the position reference pattern 24 may be partially overlapped with the first projection pattern 23 or may be entirely overlapped.

  Each embodiment and modification may be used in appropriate combination, but detailed description is omitted. Further, the present invention is not limited by the embodiments described above.

DESCRIPTION OF SYMBOLS 1 Light irradiation apparatus 2 Light irradiation system 10 Diffractive optical element 11 High refractive index part 11a Convex part 11a Convex part 11a-1 Level 1 step part 11a-2 Level 2 step part 11a-3 Level 3 step part 11a-4 Level 4 step Part 11b Side wall part 12 Recess 13 Space 14 Low refractive index part 15 Diffraction layer 20 Light source part 21 Light 22 Irradiation area 23 First projection pattern 24 Position reference pattern 24a Straight line 24b Triangle 30 Camera 40 Correction processing part 115 Diffraction layer 500 Screen

Claims (15)

A diffractive optical element for shaping light,
As a projection pattern projected by diffracting and emitting incident light,
A first projection pattern;
A position reference pattern for specifying a position in the projection pattern, which is a projection pattern different from the first projection pattern;
A diffractive optical element comprising a diffraction grating for projecting. The diffractive optical element according to claim 1,
The diffraction grating is configured such that the luminance of the position reference pattern is lower than the luminance of the first projection pattern;
A diffractive optical element characterized by the above. The diffractive optical element according to claim 2,
The diffraction grating is configured so that the brightness of the position reference pattern is 1/10 or more and 2/3 or less of the brightness of the first projection pattern;
A diffractive optical element characterized by the above. A light source unit;
A diffractive optical element that is disposed at a position to which light from the light source unit is irradiated, and shapes and emits light from the light source unit;
With
The projection pattern projected from the diffractive optical element is:
A first projection pattern;
A position reference pattern for specifying a position in the projection pattern, which is a projection pattern different from the first projection pattern;
A light irradiation apparatus including: In the light irradiation apparatus of Claim 4,
The position reference pattern specifies at least three positions;
The light irradiation apparatus characterized by this. In the light irradiation apparatus of Claim 4 or Claim 5,
The position reference pattern is arranged around a projection range of the first projection pattern;
The light irradiation apparatus characterized by this. In the light irradiation apparatus of Claim 6,
The position reference pattern is disposed along an outer shape of a projection range of the first projection pattern;
The light irradiation apparatus characterized by this. In the light irradiation apparatus in any one of Claim 4 to Claim 7,
The luminance of the position reference pattern is lower than the luminance of the first projection pattern;
The light irradiation apparatus characterized by this. In the light irradiation apparatus of Claim 8,
The brightness of the position reference pattern is 1/10 or more and 2/3 or less of the brightness of the first projection pattern;
The light irradiation apparatus characterized by this. A light source unit;
A diffractive optical element that is disposed at a position to which light from the light source unit is irradiated, and shapes and emits light from the light source unit;
A camera for obtaining an image of a projection pattern projected from the diffractive optical element; and
With
The projection pattern projected from the diffractive optical element is:
A first projection pattern;
A position reference pattern for specifying a position in the projection pattern, which is a projection pattern different from the first projection pattern;
Including
further,
A correction processing unit that analyzes an image of the projection pattern acquired by the camera and corrects distortion of the projection pattern caused by the camera based on a position of the position reference pattern;
A light irradiation system comprising: The light irradiation system according to claim 10, wherein
The brightness of the position reference pattern is lower than the brightness of the first projection pattern;
Light irradiation system characterized by. The light irradiation system according to claim 11,
The brightness of the position reference pattern is 1/10 or more and 2/3 or less of the brightness of the first projection pattern;
Light irradiation system characterized by. A projection pattern correction method for correcting distortion of a projection pattern when a projection pattern projected by a diffractive optical element that shapes and emits light from a light source is further captured by a camera,
The diffractive optical element is
A first projection pattern;
A position reference pattern for specifying a position in the projection pattern, which is a projection pattern different from the first projection pattern;
Project a projection pattern containing
The camera captures the projection pattern;
The correction processing unit corrects the distortion of the image of the projection pattern generated by the camera based on the position of the position reference pattern included in the image of the projection pattern captured by the camera;
Projection pattern correction method. The method of correcting a projection pattern according to claim 13,
The luminance of the position reference pattern is lower than the luminance of the first projection pattern;
A projection pattern correction method characterized by the above. The method of correcting a projection pattern according to claim 14,
The brightness of the position reference pattern is 1/10 or more and 2/3 or less of the brightness of the first projection pattern;
A projection pattern correction method characterized by the above.

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