JP7342354B2 - light irradiation device - Google Patents

Description

The present invention relates to a light irradiation device, a method for manufacturing a light irradiation device, a diffractive optical element multifaceted body, a method for manufacturing a diffractive optical element multifaceted body, a diffractive optical element, and a method for manufacturing a diffractive optical element.

Conventionally, technologies such as WLO (Wafer Level Optics) and WLP (Wafer Level Package) have been developed in the field of camera modules and the like. These technologies such as WLO and WLP are based on refractive lenses as optical elements, and unless the optical axis is aligned with the light source and sensor part, the performance will not be fully demonstrated and will not function properly. A common method is to create multiple images for each image.

In the above-mentioned conventional technology, since multi-sided mounting is performed for each module chip size, positioning of the light source, sensor member, and optical element is important. In particular, when bonding a light source or a sensor member to an optical element, if there is a pitch shift from one end of the multifaceted assembly to the other, the optical axes may not match in some parts, which may lead to a decrease in yield.

Furthermore, if there is a positional misalignment between the lens area formed in the optical element and the light source, the light from the light source may be transmitted to an area where the lens has no deflection effect or an area where the deflection effect is different from the original deflection effect of the lens. In some cases, the desired light distribution characteristics cannot be obtained for the light that has passed through the optical element.

Therefore, the positioning process is complicated, and it is necessary to improve the dimensional accuracy of each member. These are factors that increase costs, and improvements have been desired.

Further, in WLO, WLP, etc., cutting is performed to separate into chip size pieces. The dust generated during cutting deteriorates the performance of the optical element, and it has been desired to suppress the generation of dust. In particular, in the case of a diffractive optical element (DOE), which is an optical element equipped with a diffraction grating, the diffraction grating is made up of fine irregularities, so if dust is generated during cutting and adheres to the irregularities, Since it is difficult to remove and has a large effect on optical properties, there has been a desire for a method that can suppress the generation of dust during cutting and facilitate manufacturing.
In addition, in recent years, PLP (Panel Level Package) technology has been developed as an alternative technology to WLO, WLP, etc., but like WLO, WLP, etc., cutting is required to separate into chip size pieces. Therefore, it is also necessary to suppress dust generation.

Japanese Patent Application Publication No. 2003-302526

The problems of the present invention are to provide a light irradiation device that is easy to manufacture and can improve optical characteristics, a method for manufacturing the light irradiation device, a diffractive optical element multifaceted body, a method for manufacturing a diffractive optical element multifaceted body, and a diffractive optical element multifaceted body. An object of the present invention is to provide a method for manufacturing an optical element and a diffractive optical element.

The present invention solves the above problems by the following solving means. Note that, in order to facilitate understanding, the description will be given with reference numerals corresponding to the embodiments of the present invention, but the present invention is not limited thereto.

A first invention provides a light source (20, 21) that is arranged at a position where light from the light source (20, 21) is irradiated, and a plurality of diffraction gratings are formed to obtain a specific light distribution characteristic. a diffractive optical element (10) having a rectangular unit cell (17) configured as shown in FIG. This is a light irradiation device (1, 1B) in which a diffraction grating is formed up to the end of the diffraction optical element (10).

A second invention is characterized in that in the light irradiation device (1, 1B) according to the first invention, the pattern of the diffraction grating is continuous at a boundary portion where the unit cells (17) are adjacent to each other. This is a light irradiation device (1, 1B).

A third invention is the light irradiation device (1, 1B) according to the first invention or the second invention, wherein the diffractive optical element (10) has a mark (16) that is distinguishable from the diffraction grating. A light irradiation device (1, 1B) characterized by comprising:

A fourth invention is characterized in that in the light irradiation device (1, 1B) according to the third invention, the mark (16) is arranged to overlap an area in which a diffraction grating is arranged. This is a light irradiation device (1, 1B).

A fifth invention is a light irradiation device (1, 1B) according to any one of the first invention to the fourth invention, in which the unit cell (17) is irradiated with light from the light source (20, 21). The light irradiation device (1, 1B) is characterized in that it has a size that allows a plurality of devices to be arranged within the irradiation range of the light.

A sixth invention is the light irradiation device (1, 1B) according to any one of the first invention to the fifth invention, in which the unit cell (17) is arranged such that the unit cell (17) is aligned with the normal of the surface on which the uneven shape is formed. A light irradiation device (1, 1B).

A seventh invention is the light irradiation device (1, 1B) according to any one of the first to sixth inventions, wherein the diffractive optical element (10) is formed with at least the diffraction grating. This light irradiation device (1, 1B) is characterized by having a chamfered portion (18) at the end portion on the surface side.

An eighth invention is the light irradiation device (1, 1B) according to the seventh invention, in which the diffractive optical element (10) includes a base material (12) made of glass, and the chamfered portion (18) ) is a light irradiation device (1, 1B) characterized in that the light irradiation device (1, 1B) is formed at least up to a position reaching the base material (12).

A ninth invention is the light irradiation device (1, 1B) according to the seventh invention or the eighth invention, wherein the chamfered portion (18) is provided on each of both surfaces of the diffractive optical element (10). This is a light irradiation device (1, 1B) characterized by the following.

A tenth invention provides a light source multifaceted body (200) in which a plurality of light sources (20, 21) are arranged side by side, and a rectangular shape in which a plurality of diffraction gratings are formed to obtain specific light distribution characteristics. A plurality of shaped unit cells (17) are arranged side by side, and a plurality of the unit cells (17) are periodically arranged, and the unit cells (17) are intended to be cut into pieces. a bonding step of bonding the diffractive optical element multifaceted bodies (100) that are continuously arranged regardless of the area; and the light source multifaceted body (200) and the diffractive optical element multifaceted bodies joined in the bonding step. This is a method for manufacturing a light irradiation device (1, 1B), including a cutting step of cutting a body (100).

An eleventh invention is the method for manufacturing a light irradiation device (1, 1B) according to the tenth invention, wherein the pattern of the diffraction grating is continuous in a boundary portion where the unit cells (17) are adjacent to each other. This is a method of manufacturing a light irradiation device (1, 1B) characterized by the following.

A twelfth invention is the method for manufacturing a light irradiation device (1, 1B) according to the tenth invention or the eleventh invention, in which the diffractive optical element multifaceted body (100) is recognized separately from the diffraction grating. This is a method for manufacturing a light irradiation device (1, 1B), characterized in that the light irradiation device (1, 1B) is provided with a possible mark (16).

A thirteenth invention is a method for manufacturing a light irradiation device (1, 1B) according to the twelfth invention, wherein the mark (16) is arranged to overlap a region in which a diffraction grating is arranged. This is a method for manufacturing a light irradiation device (1, 1B).

A fourteenth invention is the method for manufacturing a light irradiation device (1, 1B) according to the thirteenth invention, characterized in that in the cutting step, a cutting position is determined using the mark (16). This is a method of manufacturing a light irradiation device (1, 1B).

A fifteenth invention is a method for manufacturing a light irradiation device (1, 1B) according to any one of the tenth to fourteenth inventions, in which the unit cell (17) is connected to the light source (20, 21). This is a method for manufacturing a light irradiation device (1, 1B), characterized in that the light irradiation device (1, 1B) has a size that allows a plurality of light irradiation devices to be arranged within an irradiation range of light irradiated from the light irradiation device.

A sixteenth invention is a method for manufacturing a light irradiation device (1, 1B) according to any one of the tenth invention to the fifteenth invention, wherein the unit cell (17) has a surface on which an uneven shape is formed. A light irradiation device characterized in that a diffraction grating is formed in which a boundary between a convex portion and a concave portion has a pattern including at least one of a curved line and a polygonal line connecting a plurality of line segments when viewed from the normal direction of the light irradiation device. This is a manufacturing method of (1, 1B).

A seventeenth invention is a method for manufacturing a light irradiation device (1, 1B) according to any one of the tenth to sixteenth inventions, wherein the cutting step includes at least a surface on which the diffraction grating is formed. This is a method of manufacturing a light irradiation device (1, 1B) characterized by including a chamfer forming step of forming a chamfer (18) on the side.

An 18th invention is the method for manufacturing a light irradiation device (1, 1B) according to the 17th invention, wherein the diffractive optical element multifaceted body (100) includes a base material (12) made of glass. , a method for manufacturing a light irradiation device (1, 1B), characterized in that in the chamfer forming step, the chamfer (18) is formed at least up to a position reaching the base material (12).

A nineteenth invention is the method for manufacturing a light irradiation device (1, 1B) according to the seventeenth invention or the eighteenth invention, in which the chamfered portion forming step includes the joined light source multifaceted body (200) and A light irradiation device characterized in that processing is performed from both sides of the diffractive optical element multifaceted body (100) so as to form the chamfered portions (18) on each of both sides of the diffractive optical element multifaceted body (100). This is a manufacturing method of (1, 1B).

A 20th invention is a method for manufacturing a light irradiation device (1, 1B) according to any one of the 17th invention to the 19th invention, in which, in the chamfered portion forming step, the light source multifaceted body (200) and the diffractive optical element multifaceted body (100) are in a connected state without being separated into pieces, and after the chamfered portion forming step, the light source multifaceted body (200) and the diffractive optical element multifaceted body ( 100) into individual pieces.

The twenty-first invention is characterized in that a plurality of rectangular unit cells (17) each having a plurality of diffraction gratings and configured to obtain a specific light distribution characteristic are arranged side by side, and the unit cells (17) are arranged side by side. A diffractive optical element polyhedral body (100) is configured by periodically arranging a plurality of unit cells (17), and the unit cells (17) are continuously arranged regardless of the area to be cut into pieces. It is.

A twenty-second invention is characterized in that in the diffractive optical element multifaceted body (100) according to the twenty-first invention, the pattern of the diffraction grating is continuous at a boundary portion where the unit cells (17) are adjacent to each other. This is a diffractive optical element multifaceted body (100).

A twenty-third invention is a diffractive optical element multifaceted body (100) according to the twenty-first invention or the twenty-second invention, comprising a mark (16) that is distinguishable from the diffraction grating, and wherein the mark (16) This is a diffractive optical element multifaceted body (100) characterized in that it is disposed overlapping a region in which a diffraction grating is disposed.

A twenty-fourth invention is characterized in that in the diffractive optical element multifaceted body (100) according to the twenty-third invention, the mark (16) is arranged for each straight line to be cut. This is a diffractive optical element multifaceted body (100).

A twenty-fifth invention is the diffractive optical element multifaceted body (100) according to the twenty-third invention or the twenty-fourth invention, wherein the marks (16) are arranged for each region to be cut into pieces. This is a diffractive optical element multifaceted body (100) characterized by the following.

A twenty-sixth invention is the diffractive optical element multifaceted body (100) according to any one of the twenty-first to twenty-fifth inventions, wherein the unit cell (17) is formed by a surface having an uneven shape. A multifaceted diffractive optical element characterized by forming a diffraction grating having a pattern in which the boundary between a convex portion and a concave portion includes at least one of a curved line and a polygonal line connecting a plurality of line segments when viewed from the line direction. body (100).

The twenty-seventh invention is characterized in that a plurality of rectangular unit cells (17) each having a plurality of diffraction gratings and configured to obtain a specific light distribution characteristic are arranged side by side, and the unit cells (17) are arranged side by side. A method for manufacturing a diffractive optical element multifaceted body (100) for producing a diffractive optical element multifaceted body (100) configured by periodically arranging a plurality of diffractive optical elements, the method comprising dividing a region in which a diffraction grating is formed into a plurality of regions. a mold preparation step of preparing molds (300, 401, 402, 403) corresponding to the divided regions; and a molding step of molding a diffraction grating using the molds (300, 401, 402, 403). A method for manufacturing a diffractive optical element multifaceted body (100) comprising the steps of:

A twenty-eighth invention is a method for manufacturing a diffractive optical element multifaceted body (100) according to the twenty-seventh invention, wherein the molding step uses the same mold (300, 401, 402, 403). This is a method for manufacturing a diffractive optical element multifaceted body (100), including the step of sequentially shaping different regions using a method.

A twenty-ninth invention is the method for manufacturing a diffractive optical element multifaceted body (100) according to the twenty-seventh invention or the twenty-eighth invention, wherein the unit cell (17) A diffractive optical element multifaceted body characterized in that a diffraction grating is formed in which the boundary between a convex portion and a concave portion has a pattern including at least one of a curved line and a polygonal line connecting a plurality of line segments when viewed from the direction. (100).

The 30th invention has a rectangular unit cell (17) configured to have a plurality of diffraction gratings and obtain a specific light distribution characteristic, and the diffraction grating is formed up to the end. , a diffractive optical element (10) having a chamfered portion (18) at least at an end portion on the side of the surface on which the diffraction grating is formed.

A 31st invention is the diffractive optical element (10) according to the 30th invention, in which the unit cell (17) is located at the boundary between the convex portion and the concave portion when viewed from the normal direction of the surface on which the concavo-convex shape is formed. This is a diffractive optical element (10) characterized in that a diffraction grating is formed having a pattern including at least one of a curved line and a polygonal line connecting a plurality of line segments.

A 32nd invention is the diffractive optical element (10) according to the 30th invention or the 31st invention, which includes a base material (12) made of glass, and the chamfered portion (18) is arranged at least in the base material. The diffractive optical element (10) is characterized in that it is formed to a position that reaches the material (12).

A 33rd invention is the diffractive optical element (10) according to any one of the 30th invention to the 32nd invention, wherein the chamfered portion (18) is provided on each of both surfaces of the diffractive optical element (10). This is a diffractive optical element (10) characterized by:

A thirty-fourth invention is a method for manufacturing a diffractive optical element (10) according to any one of the thirty-third inventions, wherein a plurality of diffraction gratings are formed to obtain specific light distribution characteristics. A plurality of rectangular unit cells (17) configured to a cutting step of cutting the diffractive optical element multifaceted body (100) that is continuously arranged regardless of the area where the diffractive optical element is to be separated into pieces; This is a method for manufacturing a diffractive optical element (10) including a chamfer forming step of forming a chamfer (18) at the end of the surface.

According to the present invention, a light irradiation device that is easy to manufacture and can improve optical characteristics, a method for manufacturing the light irradiation device, a diffractive optical element multifaceted body, and a method for manufacturing a diffractive optical element multifaceted body are provided. can do.

It is an exploded perspective view of light irradiation device 1 of a 1st embodiment. 1 is a perspective view of a light irradiation device 1. FIG. 1 is a sectional view of a light irradiation device 1. FIG. 4 is a plan view of the diffractive optical element 10 seen from above in FIG. 3. FIG. 5 is a diagram in which the pattern of the diffraction grating is omitted from FIG. 4; FIG. 5 is a diagram showing only the pattern of the diffraction grating from FIG. 4. FIG. 7 is a perspective view showing an example of a partial periodic structure in the example of the unit cell 17 in FIG. 6. FIG. FIG. 2 is a cross-sectional view schematically showing a diffractive optical element. 1 is a diagram showing a diffractive optical element wafer 100 and a light source wafer 200 used for manufacturing the light irradiation device 1. FIG. FIG. 2 is a cross-sectional view showing a state in which a diffractive optical element wafer 100 and a light source wafer 200 are bonded together. It is a figure explaining an example of imprint molding. It is a figure explaining other examples of imprint molding. It is a sectional view of light irradiation device 1B of a 2nd embodiment. FIG. 6 is a diagram showing a cutting process in which a diffractive optical element wafer 100 and a light source wafer 200 are cut in a state where they are bonded together. FIG. 6 is a diagram showing a cutting process in which a diffractive optical element wafer 100 and a light source wafer 200 are cut in a state where they are bonded together. FIG. 3 is a cross-sectional view of a diffractive optical element 10 according to a third embodiment. 5 is a diagram showing a cutting process of cutting the diffractive optical element wafer 100. FIG. FIG. 7 is a diagram illustrating an example in which the chamfered portion 18 is formed and cut into pieces using only a rotary blade with a V-shaped tip. It is a figure showing the test situation of a 4-point bending test. 20 is a cross-sectional view of three types of test pieces taken along arrow AA in FIG. 19. FIG. FIG. 2 is a diagram summarizing experimental conditions and experimental results. It is a graph showing the relationship between the angle of the chamfer and the maximum bending stress obtained from experimental results. FIG. 2 is a diagram illustrating an enlarged photograph of an end face of an actually cut diffractive optical element. FIG. 3 is a diagram illustrating dimensions of a chamfered portion 18.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings and the like.

(First embodiment)
FIG. 1 is an exploded perspective view of a light irradiation device 1 according to the first embodiment.
FIG. 2 is a perspective view of the light irradiation device 1.
FIG. 3 is a sectional view of the light irradiation device 1.
Note that each figure shown below, including FIGS. 1 to 3, is a schematic view, and the size and shape of each part are appropriately exaggerated for easy understanding.
Further, in the following description, specific numerical values, shapes, materials, etc. are shown, but these can be changed as appropriate.

In this specification, terms that specify shapes or geometrical conditions, such as terms such as parallel and orthogonal, do not have strict meanings, but also mean that they have similar optical functions and can be considered parallel or orthogonal. This also includes states with errors.
In this specification, words such as plate, sheet, film, etc. are used, but these are generally used in the order of thickness, such as plate, sheet, film, etc. This is also used in the book. However, since there is no technical meaning in these different uses, these words can be replaced as appropriate.
Furthermore, in the present invention, transparent refers to something that transmits at least light of the wavelength to be used. For example, even if a material does not transmit visible light, if it transmits infrared rays, it will be treated as transparent when used for infrared purposes.

As shown in FIG. 1, the light irradiation device 1 includes a diffractive optical element 10 and a light source section 20.
The light irradiation device 1 of this embodiment may be used by emitting, for example, an irradiation pattern representing a barcode, or may emit an irradiation pattern representing various information from a vehicle or the like onto a road surface. Further, the light irradiation device 1 may be used for irradiation of detection light in distance measurement, human body detection, three-dimensional object recognition, etc. Further, the light irradiation device 1 may be integrated with a device that captures reflected light from an object using a camera or the like, and in that case, distance measurement, 3D recognition, human body measurement, object recognition, and bar recognition are possible.

The diffractive optical element (optical element) 10 is an element called a DOE that shapes the light by controlling the traveling direction of the light by a diffraction phenomenon, and is formed in a plate shape.
In the present invention, "shaping the light" means controlling the traveling direction of the light so that the shape (irradiation pattern) of the light projected onto the target object or target area becomes an arbitrary shape, This refers to flattening the intensity distribution within the irradiation pattern or making it entirely or partially have an arbitrary intensity distribution. For example, when a light source projects directly onto a planar diffractive optical element, the irradiation spot is circular. The process of making the irradiation pattern into a desired shape, such as a combination of squares, a rectangle, or a circle, by transmitting this light through a diffractive optical element is called "shaping the light."

The diffractive optical element 10 includes a high refractive index section 11, a base material 12, and an adhesive layer 13, and is arranged at a position where light from a light source section 20 is irradiated.
The high refractive index section 11 is formed by using an original plate on which a concavo-convex shape corresponding to a diffraction grating is formed, for example, by shaping an ultraviolet curable resin coated on a base material to transfer the concavo-convex shape, and then irradiating it with ultraviolet rays. It can be formed by hardening.

As the ultraviolet curing resin, for example, urethane acrylate type, polyester acrylate type, epoxy acrylate type, polyether acrylate type, polythiol type, butadiene acrylate, etc. can be used. Note that the material for forming the high refractive index portion 11 is not limited to ultraviolet curing resin. The high refractive index portion 11 may be formed of, for example, an electron beam cured resin. Further, the high refractive index section 11 may be configured using thermosetting or ultraviolet curing SOG (Spin on Glass). Further, the uneven shape corresponding to the diffraction grating is not limited to the example of transferring from the original plate by molding, but may be formed using a resin intermediate plate made from the original plate having the above-mentioned uneven shape.

The base material 12 is a member that becomes a base when forming the high refractive index section 11. As the base material 12, for example, glass can be used. In addition, the base material 12 is not limited to glass, but may also include polycarbonate (PC) resin, polyethylene terephthalate (PET) resin, methyl methacrylate-butadiene-styrene (MBS) resin, methyl methacrylate-styrene (MS) resin, acrylic resin, etc. Transparent resins such as styrene (AS) resin and acrylonitrile butadiene styrene (ABS) resin can be used. In this embodiment, the base material 12 is made of glass, so it is formed in a plate shape, but it may also be a resin sheet or a resin film.
The adhesion layer 13 is a primer layer coated on the base material 12 to improve adhesion with ultraviolet curing resin and the like. Note that the adhesive layer 13 may be omitted.
Details regarding the diffractive optical element 10 will be described later.

The light source section 20 includes a light emitting element (light source) 21, a substrate 22, and a holder 24.
The light emitting element (light source) 21 emits infrared light, blue light, etc., and projects the light onto the diffractive optical element 10. As the light emitting element 21, for example, a laser light source such as a vertical cavity surface emitting laser (VCSEL) may be used, or an LED (light emitting diode) may be used. The light emitting element 21 is mounted on a substrate 22. Note that depending on the form of the light emitting element 21, the wiring 23 may be used to connect it to the substrate. In this embodiment, the light emitting element 21 is a vertical cavity surface emitting laser that emits light with a wavelength of 850 nm.

The holder 24 is formed into a frame shape on which the diffractive optical element 10 is mounted. The holder 24 is made of engineering plastic such as polyamide or polycarbonate, for example. In order to make the holder 24 difficult to deform, polycarbonate or the like may contain glass fiber.
The holder 24 has a penetrating opening at its center. The holder 24 includes a top portion 24a on which a peripheral portion of the diffractive optical element 10 is placed. The diffractive optical element 10 is placed and fixed on top of this top portion 24a via an adhesive 60. In addition, although the top part 24a of the holder 24 of this embodiment is comprised by a plane, you may further provide a groove|channel.
The holder 24 is attached to the substrate 22 on its back side (lower side in FIG. 3) using an adhesive (not shown) or the like.

FIG. 4 is a plan view of the diffractive optical element 10 seen from above in FIG.
FIG. 5 is a diagram in which the diffraction grating pattern is omitted from FIG. 4.
Marks 16 are arranged at multiple locations on the surface of the diffractive optical element 10. In this embodiment, the mark 16 is placed overlapping the area where the diffraction grating pattern is placed.

The mark 16 is used, for example, as various marks, standards, etc. for detection using an optical detection device.
The mark 16 is formed by a collection of patterns having a plurality of concave and convex shapes, and can be easily recognized optically by reflection of light by the edges of the concave and convex shapes. As the uneven shape, for example, a line and space pattern, a hole pattern, a dot pattern, etc. can be used. One type of uneven shape may be used to form a pattern aggregate, or a plurality of types may be used to form a pattern aggregate. The uneven shapes of these patterns can have a certain periodicity.

If the pitch is the combined width of a pair of adjacent concave and convex portions of the concave and convex shapes forming the mark 16, the pitch of the concave and convex shapes forming the mark 16 is particularly limited as long as it is easy to detect with an optical detection device. Not allowed. For example, by making the pitch of the uneven shapes wider than the pitch of the diffraction grating pattern described later, manufacturing of the diffractive optical element 10 is not hindered. Further, the finer the pitch, the easier it is to detect due to the reflection of light at the edge portion of the uneven shape. For example, the pitch may be set to about 500 nm to 10 μm, more preferably 1 μm to 5 μm. Furthermore, multiple types of pitches may be included.
The duty ratio, which is the ratio of the respective widths of a set of concave portions and convex portions, may be 1:1, which is easy to detect with an optical detection device, but the duty ratio may be varied within a range that can be manufactured.
In this embodiment, the marks 16 are formed as line-and-space patterns all oriented in the same direction in accordance with the direction of molding. The pitches of the concave portions and convex portions are all constant, and the duty ratio is 1:1.
Further, the maximum depth of the recessed portion of the mark 16 is preferably equal to or deeper than the maximum depth of the diffraction grating. As the recessed portion of the mark 16 becomes deeper, identification becomes easier.
Note that if the detection accuracy of the mark 16 is degraded due to the specifications of the apparatus for forming the diffractive optical element 10, the mark 16 may be made of another reflective or light-shielding material instead of the uneven structure. In that case, the mark is formed by printing. Although general methods such as photolithography and the like can be used, photolithography is preferably used when metal or the like is used. In the diffractive optical element 10, it is formed on the front or back surface of the base material 12.

Next, the pattern of the diffraction grating provided in the diffractive optical element 10 will be explained in more detail.
FIG. 6 is a diagram showing only the pattern of the diffraction grating from FIG. 4.
In the diffractive optical element 10, a plurality of unit cells 17 are periodically arranged side by side. This unit cell 17 is configured to have a plurality of diffraction gratings formed therein so as to have a specific light distribution characteristic, that is, to shape light into a desired pattern. For this purpose, a diffraction grating having an uneven shape is designed and arranged on the high refractive index section 11 so that the desired light distribution characteristics can be obtained with only the unit cell 17. The plurality of unit cells 17 all have the same diffraction grating configuration, and a plurality of unit cells 17 having the same uneven shape (diffraction grating) are arranged side by side.
Further, the unit cells 17 are arranged without any interval between them, and the pattern of the diffraction grating is set to be continuous at the boundary portion where the unit cells are adjacent to each other.
Furthermore, the diffraction grating is formed up to the end of the diffractive optical element 10 without providing any blank space or the like.
In this embodiment, one diffractive optical element 10 is formed in a square of 3 mm x 3 mm, and the unit cell 17 is set as a square of 0.6 mm x 0.6 mm. Therefore, 25 unit cells 17 are arranged on the surface of the diffractive optical element 10.

The light emitting element 21 irradiates light onto the diffractive optical element 10, and the irradiation area may be the entire surface of the diffractive optical element 10, but is usually approximately 50% of the element area of the diffractive optical element 10, for example. ~80%. A plurality of unit cells 17 are arranged within this light irradiation area. For example, even if the light irradiation area is 50% of the element area of the diffractive optical element 10, in the example of this embodiment, 12.5 unit cells 17 are arranged. Furthermore, in the diffractive optical element 10 of this embodiment, diffraction gratings are arranged over the entire surface. Therefore, the light irradiation device 1 of this embodiment can always emit appropriately shaped light even if there is a relative positional shift between the diffractive optical element 10 and the light emitting element 21.

Note that in FIG. 6, the unit cells 17 are shown in a large size for easy understanding, and an example is shown in which nine unit cells 17 are arranged in one diffractive optical element 10. In addition, the boundaries of the unit cells 17 are intentionally expressed in an easy-to-understand manner so that the individual unit cells 17 can be easily understood, but in reality, the boundaries of the unit cells 17 are made up of continuous diffraction grating patterns. It is difficult to distinguish because of the presence of

The unit cell 17 of this embodiment has different depths at different positions in the different hatched areas shown in FIG. That is, the unit cell 17 has a multi-stage shape with four different heights. The unit cell 17 usually has a plurality of regions (partial periodic structures) having different periodic structures.

FIG. 7 is a perspective view showing an example of a partially periodic structure in the example of the unit cell 17 of FIG.
FIG. 8 is a cross-sectional view schematically showing a diffractive optical element.
The pattern of the diffraction grating configured in the unit cell 17 is configured of curved lines, but depending on the target output pattern of the diffractive optical element, it may be a straight line or a polygonal line connecting line segments consisting of curved lines. It may also include patterns. Therefore, in the pattern of the diffraction grating of this embodiment, the boundary between the convex part and the concave part has a curved line and a plurality of line segments when viewed from the normal direction of the surface on which the concavo-convex shape of the high refractive index section 11 (described later) is formed. Includes at least one of the connected polygonal lines.
The diffractive optical element 10 has a complicated shape as shown in FIG. 7, but to simplify and schematically show it, as shown in FIG. 8, a plurality of convex portions 11a are arranged side by side in the cross-sectional shape. A high refractive index section 11 is provided.

The high refractive index portion 11 may be made by processing quartz (SiO ₂ , synthetic quartz) into a shape by etching, for example. Further, the high refractive index portion 11 is made by cutting a mold from a processed quartz or silicon wafer, and using this mold to harden the ionizing radiation curable resin composition. Good too. Various methods are known for manufacturing objects with such a periodic structure using an ionizing radiation-curable resin composition, and the high refractive index portion 11 of the unit cell 17 (diffractive optical element 10) can be manufactured using any of these known methods. It can be produced as appropriate using the method described above.

In addition, air exists in the upper part of FIG. 8 including the recesses 14a formed between the convex parts 11a and the space 14b near the top of the convex parts 11a, and the refractive index is higher than that of the high refractive index part 11. This is a low refractive index portion 14 with a low refractive index. A periodic structure in which the high refractive index portions 11 and the low refractive index portions 14 are arranged alternately constitutes a diffraction layer 15 having the function of shaping light.

The convex portion 11a of this embodiment has a multi-step shape with four step portions having different heights on one side (the left side in FIG. 8) of the side surface shape. Specifically, the convex portion 11a includes a level 1 stepped portion 11a-1 that is the most protruding, a level 2 stepped portion 11a-2 that is one step lower than the level 1 stepped portion 11a-1, and a level 2 stepped portion 11a-2 that is lower than the level 2 stepped portion 11a-2. It also has a level 3 step section 11a-3 which is one step lower than the level 3 step section 11a-3, and a level 4 step section 11a-4 which is one step lower than the level 3 step section 11a-3 on one side. Further, the other side (the right side in FIG. 8) of the side surface shape of the convex portion 11a is a side wall portion 11b that extends linearly from the level 1 step portion 11a-1 to the level 4 step portion 11a-4.
In the light irradiation device of this embodiment, since the light emitting element 21 is a laser light source with a wavelength of 850 nm, the diffraction grating of the unit cell 17 is optimal for diffracting light with a wavelength of 850 nm. It is structured to a certain depth.

The partial periodic structure formed by the multi-stage shape as described above is formed so that each partial periodic structure is different mainly in the arrangement pitch and the arrangement direction. Each partial periodic structure diffracts the light, deflects it in a predetermined direction, and emits the light, so that one partial periodic structure irradiates the light as a very small dot. A large number of these partial periodic structures each configured to deflect light in a desired direction are arranged in the unit cell 17, and as a whole, it is possible to project an irradiation pattern in which light is shaped into a desired shape. ing.

Next, a method for manufacturing the light irradiation device 1 of this embodiment will be explained.
In this embodiment, instead of joining the light source section 20 and the diffractive optical element 10 for each individual light irradiation device 1, a method called WLO (Wafer Level Optics) or WLP (Wafer Level Package) is further improved. used.
FIG. 9 is a diagram showing a diffractive optical element wafer 100 and a light source wafer 200 used for manufacturing the light irradiation device 1.
FIG. 10 is a cross-sectional view showing a state in which the diffractive optical element wafer 100 and the light source wafer 200 are bonded together.
In this embodiment, a diffractive optical element wafer 100 and a light source wafer 200 as shown in FIG. 9 are manufactured.
Here, the diffractive optical element wafer 100 is a multifaceted diffraction grating body in which a plurality of unit cells are arranged side by side, and the light source wafer 200 is a light source multifaceted body in which a plurality of light sources are arranged side by side. In the following explanation, a wafer-shaped (circular) diffractive optical element wafer 100 and a light source wafer 200, which are generally used in WLO, WLP, etc., are taken as examples. The shape of the body is not limited to a wafer shape (circular shape), but may be a rectangular panel shape used in PLP (Panel Level Package) or the like.

To manufacture the diffractive optical element wafer 100 of this embodiment, first, an adhesive layer 13 is coated on a circular glass base material 12 having a diameter of 8 inches. Then, on the adhesive layer 13, an uncured ultraviolet curable resin that will become the high refractive index portion 11 is applied, and an original plate (molding mold) to be described later is pressed onto this to form an uneven shape, and then ultraviolet rays are irradiated. The diffractive optical element wafer 100 is completed by curing the wafer.
Here, the diffraction grating formed on the diffractive optical element wafer 100 is composed of a plurality of unit cells 17 arranged periodically. Further, the unit cells 17 on the diffractive optical element wafer 100 are continuously arranged regardless of the area where they are planned to be cut into pieces. That is, on the diffractive optical element wafer 100, there is no distinction between regions in which the diffraction grating to be formed into the high refractive index portion 11 is to be cut into pieces. However, the mark 16 is provided for each area scheduled to be cut into pieces.
In this embodiment, the concavo-convex shape of the diffraction grating was formed only in necessary regions, such as the hatched region A on the diffractive optical element wafer 100 in FIG. However, the uneven shape of the diffraction grating may be formed on the entire surface of the diffractive optical element wafer 100.

To manufacture the diffractive optical element wafer 100, as described above, an original plate having an uneven shape of a diffraction grating is prepared in advance, imprint molding is performed using this original plate, and the uneven shape is transferred (imprinted) onto an ultraviolet curable resin. ). Preparing this original plate requires a lot of effort and the manufacturing cost is high, so it is inefficient and impractical to prepare an 8-inch size original as described above. Therefore, in this embodiment, a large diffractive optical element wafer 100 is efficiently manufactured by dividing the 8-inch size diffractive optical element wafer 100 into a plurality of regions and using an original smaller than the entire size.

FIG. 11 is a diagram illustrating an example of imprint molding. Note that the hatched area in FIG. 11 indicates the area where the uneven shape of the diffraction grating is arranged and the original plate corresponding thereto.
In the example shown in FIG. 11, the surface of the diffractive optical element wafer 100 is divided into four regions, and an original plate (molding mold) 300 corresponding to one of the regions is prepared (molding mold preparation step). Then, using this original plate 300, a molding step of molding a diffraction grating is performed. This original plate 300 can be used in all four areas by rotating and changing its orientation. Therefore, in this example, it is possible to manufacture a diffractive optical element wafer 100 larger than the original plate 300 by preparing one original plate 300 and performing a step of sequentially forming different regions using the same original plate 300. Note that four original plates 300 may be prepared and the entire forming process may be completed in one forming process.
In addition, in FIG. 11, a slight gap is provided between the four divided areas, but this gap may be eliminated.

FIG. 12 is a diagram illustrating another example of imprint molding. Note that the hatched area in FIG. 12 indicates the area where the uneven shape of the diffraction grating is arranged and the original plate corresponding thereto.
In the example shown in FIG. 12, the surface of the diffractive optical element wafer 100 is divided into three types of 12 areas, and original plates (molding molds) 401, 402, 403 corresponding to each type of area are prepared (molding mold preparation). process). Then, using these original plates 401, 402, and 403, a molding step is performed to shape a diffraction grating. Since there are four areas corresponding to each of the original plates 401, 402, and 403, you may perform the imprinting on each area sequentially, or prepare four each of the original plates 401, 402, and 403 and perform imprinting in one time. It may also be a mold process.
In addition, in FIG. 12, the 12 divided regions are arranged in close contact with each other, but a slight gap may be provided between each region.

Returning to FIGS. 9 and 10, the light source wafer 200 has a configuration in which the components that become the light source sections 20 are closely arranged side by side. Regarding the boundaries of the parts that will become individual light source parts 20 by being cut into individual pieces, in the state of the light source wafer 200, they are connected and have no clear boundaries, and the parts that become the walls of the holder 24 are formed. ing.

After the above-described diffractive optical element wafer 100 and light source wafer 200 are fabricated and prepared, a bonding process for bonding them is performed. Specifically, an adhesive 60 is applied onto the top portion 24a to bond the diffractive optical element wafer 100 and the light source wafer 200 together.
Next, a cutting process is performed to cut the diffractive optical element wafer 100 and the light source wafer 200 that have been bonded in the above bonding process, and the light irradiation device 1 is completed by cutting them into pieces.

Here, in the cutting process, cutting is performed at the positions indicated by arrows in FIG. 10, but it is very advantageous that the diffraction gratings formed on the diffractive optical element wafer 100 are arranged without distinguishing regions. work. That is, even if there is a slight positional shift in the cutting position of the diffractive optical element wafer 100, it will not affect the light shaping characteristics, that is, the light distribution characteristics of the light emitted by the light irradiation device 1. . This has a light shaping effect that allows the necessary light distribution characteristics to be obtained with only the unit cell 17, and the unit cell 17 is sufficiently smaller than the irradiation area of the light from the light emitting element 21, and the irradiation area is This is because a large number of unit cells 17 are arranged within the structure.

Such a configuration is difficult to realize with a refractive lens, and when a conventional refractive lens is used, it is required to accurately align the optical axis of the lens with the light emitting element 21. Furthermore, even if a diffractive optical element is used, with the conventional configuration in which a diffraction grating is provided only in the irradiation area, if the alignment is not accurate, light may leak in unnecessary directions and the efficiency of light use may decrease. A phenomenon was occurring. Therefore, conventionally, it was necessary to accurately align the relative positions of the light emitting element side and the optical element (lens) side. For this purpose, it was necessary to control the dimensions of both the diffractive optical element wafer 100 and the light source wafer 200 very strictly, and to manufacture both as highly precise components.

These problems are solved in the light irradiation device 1 of this embodiment. Basically, with regard to the relative positional deviation in the in-plane direction between the diffractive optical element wafer 100 and the light source wafer 200, it is sufficient to perform rough alignment. Since there is a mark 16 on the diffractive optical element wafer 100, it is only necessary to ensure that the mark does not shift significantly. At the time of cutting, only the cutting position with respect to the light source wafer 200 needs to be adjusted, and the effort required for dimensional control during manufacturing is greatly reduced. Even though the configuration is easy to manufacture, the optical characteristics are less likely to deteriorate due to positional deviation, and as a result, the optical characteristics obtained can be improved.

Note that for in-plane angle deviations, unlike positional deviations in the in-plane direction, alignment must be done taking into account the required specifications, but it is usually sufficient to match marks at at least two distant locations. Accuracy can be ensured. In addition, physical alignment using a guide or the like is also possible, and the management effort is small.
In addition, when using in combination with another collimating lens element between the diffractive optical element and the light source, precise alignment of the lens and the light source (or the light source wafer) is required. For elements for which the lens and light source have already been precisely aligned, it is possible to perform rough alignment of the diffractive optical element, and if the diffractive optical element and lens are aligned and combined first, it is possible to align the diffractive optical element and the lens first. Since it is sufficient to use the alignment marks made for alignment with the light source, it is possible to roughly align the diffractive optical element and the lens. In the latter case, the diffractive optical element and the lens can also be formed on both sides of the substrate.
In addition, when a pattern layer having a function other than diffraction is formed on either the front or back of the base material of the diffractive optical element 10 and used, the pattern layer is designed to be aligned with the light source or the collimating lens element by looking at the pattern layer. This allows rough alignment in forming the diffractive optical element. Examples of pattern layers include a light shielding layer, an identification layer, and a wiring layer.

With such a characteristic configuration of this embodiment, in the cutting process, cutting is basically performed at equal pitches using the light source wafer 200 as a positioning reference. Note that cutting may be performed using marks provided on the diffractive optical element wafer 100 or the light source wafer 200 as a reference. In that case, a cutting mark may be further provided on the diffractive optical element wafer 100. In this case, the mark may be placed for each area that is scheduled to be cut into pieces, or may be placed for each scheduled cutting straight line that is scheduled to be cut. Further, this mark may be provided overlapping the diffraction grating like the mark 16 shown above, or may be provided in a blank area where the diffraction grating is not formed.
Even when a mark is provided on the diffractive optical element wafer 100 and the cutting process is performed using the mark as a reference, the advantageous effects of the present embodiment described above are fully exhibited. This is because the mark provided on the diffractive optical element wafer 100 can be used to indicate the position of the light source wafer 200, which becomes difficult to see when the diffractive optical element wafer 100 is bonded. In that case, it is advisable to know how far the mark provided on the diffractive optical element wafer 100 deviates from the reference position of the light source wafer 200 during bonding or before cutting.

As explained above, the diffractive optical element 10 of the light irradiation device 1 of the present embodiment is configured with a plurality of unit cells 17 arranged periodically, and a diffraction grating is formed up to the end of the diffractive optical element 10. ing. Further, the unit cells 17 on the diffractive optical element wafer 100 are continuously arranged regardless of the area where they are planned to be cut into pieces. Therefore, high precision is not required for the relative positioning of the diffractive optical element wafer 100 and the light source wafer 200 in the in-plane direction. Furthermore, it becomes possible to perform rough positioning in the cutting process. Therefore, manufacturing can be performed easily and optical characteristics can be improved.

(Second embodiment)
FIG. 13 is a cross-sectional view of a light irradiation device 1B according to the second embodiment.
The light irradiation device 1B of the second embodiment differs from the light irradiation device 1 of the first embodiment in that the base material 12 is made of glass and that it is provided with a chamfered portion 18. It has a similar form to the light irradiation device 1 of the first embodiment. Therefore, parts that perform the same functions as those in the first embodiment described above are given the same reference numerals, and redundant explanations will be omitted as appropriate.

The base material 12 of the light irradiation device 1B of the second embodiment is made of glass. By using glass as the base material, even if the thickness of the diffractive optical element 10 is reduced, it is difficult to bend and it is possible to provide a highly accurate diffractive optical element. On the other hand, since glass is generally more brittle than resin materials, there is a high possibility that fine chips or the like will occur at the cut location during the cutting process. If a chipped portion occurs in the base material 12, the strength of the diffractive optical element 10 may deteriorate.
Furthermore, as illustrated above, the diffraction grating (high refractive index portion 11) of the diffractive optical element 10 has a very complicated shape, and this shape is very fine. When this complex and fine diffraction grating is cut with a rotating blade, the high refractive index portion is peeled off due to frictional force with the rotating blade and becomes fine dust, which adheres to the diffractive optical element 10 in large quantities. There is a risk. In particular, when the base material 12 is made of glass, there is a high possibility that the diffraction grating will be further peeled off when the glass is chipped.

Therefore, in the light irradiation device 1B of the second embodiment, in the cutting process, a chamfered part forming process is performed to form the chamfered part 18 to suppress chipping of the glass base material 12, and also to suppress chipping of the glass base material 12. This suppresses the generation of dust caused by part 11).

The chamfered portion 18 is located on the side where the diffraction grating is formed, that is, the side where the high refractive index portion 11 is provided, and in FIG. It has a chamfered shape. Therefore, the chamfered portion 18 is formed into a slope. This chamfered portion 18 is formed all around the surface on which the high refractive index portion 11 is provided. Furthermore, the chamfered portion 18 is formed to a position that reaches the base material 12.
In this embodiment, the chamfered portion 18 is a slope inclined at 45 degrees with respect to the sheet surface of the diffractive optical element 10. Therefore, the bevel angle θ (half the angle of the entire blade edge, see FIG. 13) of the rotary blade B1, which will be described later, was set to 45 degrees.
Note that the chamfered portion 18 is not limited to a C-chamfer, but may be configured as an R-chamfer. In that case, a corresponding R-shaped rotary blade B1 may also be used.

14 and 15 are diagrams showing a cutting process in which the diffractive optical element wafer 100 and the light source wafer 200 are cut in a state where they are bonded together.
In the cutting process of the second embodiment, first, as shown in FIG. 14, using a rotary blade B1 with a V-shaped tip, a V cut (bevel cut) is performed from the side where the high refractive index section 11 is provided. , forming the chamfered portion 18 (chamfered portion forming step). In this chamfer forming step, V-cutting is performed until the rotary blade B1 reaches the base material 12. At this stage, the light source wafers 200 are not separated into individual pieces, and the light source wafers 200 are in a connected state.

Next, as shown in FIG. 15, a main cutting step is performed in which the light source wafer 200 and the diffractive optical element wafer 100 are cut into pieces using a rotating blade B2 whose width is narrower than the V-cut width. As a result, the light irradiation device 1B in which the chamfered portion 18 shown in FIG. 13 is formed on the diffractive optical element 10 is manufactured.

As mentioned above, by first carrying out the chamfer forming process to form the chamfered part 18 and then carrying out the main cutting process, compared to the conventional case where the main cutting process is performed at once, the following results can be achieved. You can get the following effect.

First, by forming the chamfered portion 18, the generation of dust during cutting can be significantly suppressed. In particular, it is possible to suppress the generation of dust caused by part of the high refractive index portion 11 forming the diffraction grating peeling off and falling off. By using the rotary blade B1 with a V-shaped tip, the force of scraping from a deep part does not act on the high refractive index part 11, and the force of pressing the high refractive index part 11 from the cutting side does not act. It is presumed that this effect is obtained by doing so.

Further, by forming the chamfered portion 18, chipping of the base material 12 can be suppressed. This effect is particularly great when the base material 12 is made of glass. This is because the chamfered portion 18 is formed until it reaches the base material 12, so even if a scraping force is generated on the end surface of the base material 12 from a deep part when cutting the base material 12, the end surface will not be slanted. It is presumed that it is hard to chip because of the fact that it is

Furthermore, by forming the chamfered portion 18, the bending strength can be improved when a force is applied to the base material 12 to bend the side on which the chamfered portion 18 is formed outward. This is an effect due to the fact that stress concentration does not occur due to the reduction in the number of chips in the base material 12 described above.

(Third embodiment)
FIG. 16 is a cross-sectional view of the diffractive optical element 10 of the third embodiment.
The diffractive optical element 10 of the third embodiment includes a chamfered portion 18, and has the same configuration as the diffractive optical element 10 laminated in the light irradiation device 1B of the second embodiment described above.
The second embodiment has been described using an example in which the chamfered portion 18 is formed in the light irradiation device 1B. The effect obtained by forming the chamfered portion 18 described in the second embodiment is not only obtained when cutting the bonded diffractive optical element wafer 100 and light source wafer 200. For example, even when manufacturing the diffractive optical element 10 by cutting only the diffractive optical element wafer 100, the same effect as in the second embodiment can be obtained by providing the chamfered portion 18 described above. .
The diffractive optical element 10 of the third embodiment is manufactured by performing the chamfer forming step in the cutting process of cutting the diffractive optical element wafer 100, similarly to the second embodiment, and then performing the main cutting process. It is possible. Since the diffractive optical element 10 of the third embodiment includes the chamfered portion 18, the generation of dust during cutting can be significantly suppressed, chipping of the base material 12 can be suppressed, and bending Can improve strength.

(Fourth embodiment)
FIG. 17 is a diagram showing a cutting process of cutting the diffractive optical element wafer 100.
In the fourth embodiment, a diffractive optical element 10 having chamfered portions 18 on both sides and a cutting process for manufacturing the same will be described.
In the fourth embodiment, the layer configurations of the diffractive optical element 10 and the diffractive optical element wafer 100 are different from those in the first to third embodiments. In the diffractive optical element 10 and the diffractive optical element wafer 100 of the fourth embodiment, the adhesive layer 13 provided in the first to third embodiments is omitted. Furthermore, in the diffractive optical element 10 and the diffractive optical element wafer 100 of the fourth embodiment, the guarantee function layer 19 is provided on the surface of the base material 12 on the side where the diffraction grating is not provided. The guarantee function layer 19 is a general term for various layers that can provide additional functions. The guarantee function layer 19 may be, for example, a protective film such as SiO _x or SION, an antireflection film, or an ITO film, and any function may be added thereto. Further, the guarantee function layer 19 is not limited to a single layer, and may be formed of multiple layers.

In the example shown in FIG. 17, first, a V cut (bevel cut) is performed from the surface side where the high refractive index section 11 is provided using the rotary blade B1-1 with a V-shaped tip, and the chamfered portion on the upper surface side is cut. 18 (FIG. 17(a): chamfered portion forming step).
Next, using a rotary blade B1-2 with a V-shaped tip, perform a V cut (bevel cut) from the surface side where the guarantee function layer 19 is provided to form a chamfered portion 18 on the lower surface side (FIG. 17 (b): Chamfered portion forming step).
Next, a main cutting step (FIG. 17(c)) is performed in which the diffractive optical element wafer 100 is cut into pieces using a rotary blade B2 having a width narrower than the width of the V-cut. A diffractive optical element 10 in which is formed is produced (FIG. 17(d)).
Note that after performing a V cut (bevel cut) from the side where the guarantee function layer 19 is provided, a V cut is performed from the side where the high refractive index portion 11 is provided, and then the main cutting step is performed. It's okay.

Further, the singulation may be performed using only a rotary blade having a V-shaped tip without using the rotary blade B2.
FIG. 18 is a diagram showing an example in which the chamfered portion 18 is formed and separated into pieces using only a rotary blade with a V-shaped tip.
In the example shown in FIG. 18, rotary blades B1-3 and B1-4 having a narrower bevel angle (angle of the cutting edge) than the rotary blades B1-1 and B1-2 shown in FIG. 17 are used.
First, using a rotary blade B1-3 with a V-shaped tip, perform a V cut (bevel cut) from the surface side where the high refractive index portion 11 is provided to form a chamfered portion 18 on the upper surface side (FIG. 18 (a): Chamfered portion forming step).
Next, using a rotary blade B1-4 with a V-shaped tip, perform a V cut (bevel cut) from the side where the guarantee function layer 19 is provided to form a chamfered portion to form the chamfered portion 18 on the lower surface side. This process and a main cutting process in which the diffractive optical element wafer 100 is cut into pieces are performed simultaneously (FIG. 18(b)), and the diffractive optical element 10 with chamfered portions 18 formed on both sides is manufactured (FIG. 18(b)). 18(c)).
Note that after performing a V cut (bevel cut) from the side where the guarantee function layer 19 is provided, a V cut may be performed from the side where the high refractive index portion 11 is provided.

According to the fourth embodiment described above, the chamfered portions 18 can be formed on both sides. Therefore, not only can the generation of dust and chipping of the base material 12 during cutting be suppressed, but also the bending strength in both directions can be improved. Although not shown, in the case of a diffractive optical element that includes diffraction gratings on both sides of a base material, it is particularly desirable to provide chamfered portions 18 on both sides as in this embodiment.

(Checking bending strength)
As described above, in the second to fourth embodiments, it has been explained that by providing the chamfered portion 18, the bending strength can be improved when the product is bent with the side on which the chamfered portion 18 is provided as the outside. . We conducted an experiment to prove this, and the experimental method and results are shown below.
In this experiment, the bending strength was evaluated by a four-point bending test.
FIG. 19 is a diagram showing the test situation of a four-point bending test.
As shown in FIG. 19, the test piece length Ls was 60 mm, the distance between fulcrums L was 45 mm, and the distance between load points Li was 15 mm.

FIG. 20 is a cross-sectional view of three types of test pieces taken along arrow AA in FIG. 19.
The test pieces were a test piece without a chamfer as shown in Figure 20(a), a test piece with a chamfer on the upper side as shown in Figure 20(b), and a test piece as shown in Figure 20(c) on the lower side. A test piece with chamfered parts on both sides shown in Figure 20(d), a test piece with chamfered parts on both sides that was cut after chamfering on both sides shown in Figure 20(e), and a test piece with chamfered parts on both sides shown in Figure 20(e). Five types of test pieces were prepared, each of which had chamfered portions on both sides and was separated into pieces using only shaped rotating teeth. In addition, since the high refractive index portion 11 and the like have almost no effect on the bending strength, the test piece used was only the glass base material 12. These test pieces were all produced by cutting in the same cutting process as exemplified in the above embodiment.
A load test was performed on the above test piece using an electromechanical universal material testing machine 5900 series manufactured by Instron.

FIG. 21 is a diagram summarizing experimental conditions and experimental results.
FIG. 22 is a graph showing the relationship between the angle of the chamfer and the maximum bending stress obtained from experimental results.
In the test piece without a chamfered portion, the maximum load Fmax-ave was 15.87 N, and the maximum bending stress determined from the maximum load Fmax-ave was 176.33 MPa.
For the test piece with a chamfered portion on the top side, the maximum load Fmax-ave is 13.12 N when the bevel angle θ = 30°, 14.87 N when θ = 45°, and 14.82 N when θ = 50°. , 15.94 N when θ=60°, and the maximum bending stress calculated from the maximum load Fmax-ave is 145.91 MPa when θ=30°, 165.32 MPa when θ=45°, and 165.32 MPa when θ=50°. 164.75 MPa when θ = 60°, and 177.18 MPa when θ = 60°, and there is no clear difference from the test piece without a chamfered part, or there is a slight tendency to decrease.
On the other hand, for the test piece with a chamfered portion on the lower surface side, the maximum load Fmax-ave is 16.13 N when θ = 30°, 19.27 N when θ = 45°, and 19.27 N when θ = 50°. 18.09N, 17.30N when θ=60°, and the maximum bending stress is calculated from the maximum load Fmax-ave: 179.38MPa when θ=30°, 214.24MPa when θ=45°, θ = 50°: 201.11 MPa, θ = 60°: 192.30 MPa, and the bending strength was improved compared to the test specimen without a chamfered part and the specimen with a chamfered part on the upper surface side. It could be confirmed.
In addition, for a test piece with chamfered portions on both sides, 16.27 N when θ = 30° (two-step machining using only V-shaped rotating blades) and 19 N when θ = 30° (main cutting after chamfering on both sides). .43N, 19.65N when θ=45°, 19.87N when θ=50°, 16.96N when θ=60°, and when the maximum bending stress is calculated from the maximum load Fmax-ave, θ= 181.18 MPa for 30° (2-step machining using V-shaped rotary blade only), 216.12 MPa for θ = 30° (main cutting after double-sided chamfering), 218.51 MPa for θ = 45°, θ = 50 The bending strength is 220.93 MPa for θ = 60° and 188.57 MPa for θ = 60°, which is higher than that of the specimen without a chamfer and the specimen with a chamfer on the top or bottom side. An improvement in the quality was confirmed.
This result is due to the fact that the chamfered portion suppresses chipping that occurs in the glass during cutting, making it difficult for stress concentration to occur.
As described above, when the surface side on which the chamfered portion 18 is provided is bent outward, the bending strength can be improved by providing the chamfered portion 18.

(Observation confirmation of the cut end)
FIG. 23 is a diagram showing an enlarged photograph of the end face of the actually cut diffractive optical element. FIG. 23(a) shows a photograph of a cut portion cut without a chamfered portion taken from a direction perpendicular to the diffraction grating surface of the diffractive optical element, and FIG. 23(b) shows a photograph of a cut portion cut with a chamfered portion. A photograph of the cut portion taken from a direction perpendicular to the diffraction grating surface of the diffractive optical element is shown. A reference sectional view is also shown on the right side of FIG. 23 so that the cutting position can be easily understood. In addition, in this diffractive optical element, the thickness of the glass base material 12 is 300 μm (0.3 mm), while the thickness of the high refractive index portion 11 is 5 μm or less, so the photo shows a high The details of the refractive index layer 11 cannot be confirmed.
In FIG. 23(a), it can be confirmed that the edges are rough because many glass chips occur at the edges. On the other hand, in FIG. 23(b), the chipping of the glass is slightly suppressed, the rough edges are hardly visible, and the cutting line is clean.
Further, in FIG. 23(a), the presence of dust that is considered to be fragments of the high refractive index portion 11 can also be confirmed.

(Preferred form of chamfered portion 18)
FIG. 24 is a diagram illustrating the dimensions of the chamfered portion 18.
Here, preferred dimensions for the chamfered portion 18 will be described with reference to FIG. 24.
The thickness t of the base material 12 is preferably 0.2 mm or more and 1.0 mm or less. In the glass base material 12 having the thickness t, it is preferable that the dimensions of each part of the chamfered portion 18 be within the following ranges from the viewpoint of suppressing the generation of dust and suppressing the occurrence of chipping of the base material 12. .
It is desirable that the bevel angle θ is in the range of 20 degrees or more and 70 degrees or less.
It is desirable that the bevel width W is in the range of t×5% or more and t×35% or less.
This should be wide enough to avoid chipping and dirt caused by the straight blade, and narrow enough not to affect the chip size and various functional layers on the chip (DOE pattern, ITO wiring, various marks, etc.). This is because it is desirable.
It is desirable that the groove depth D is in the range of t×5% or more and t×35% or less.
Further, it is desirable that the thickness of the high refractive index portion 11 and the thickness of the guarantee function layer 19 are both 5% or less of the thickness t of the base material 12.
Note that, although the above-mentioned range is a preferable range, the value is not limited to this range.

(Deformed form)
Various modifications and changes are possible without being limited to the embodiments described above, and these are also within the scope of the present invention.

(1) In each embodiment, the diffraction grating provided in the diffractive optical element 10 has been described using an example in which the diffraction grating has a four-level multi-stage shape. However, the diffraction grating provided in the diffractive optical element 10 may have a multi-stage shape with 8 levels or 16 levels, a 2-level uneven shape, a slanted shape in which the 2-level uneven shape is inclined, or The multi-step shaped portion may have a blazed shape that is a continuous slope. Further, the slopes of the slanted shape and the blazed shape are not limited to flat surfaces, but may be curved shapes including free-form surfaces.

(2) In each embodiment, the diffractive optical element is configured to include a base material, but it may have a simple form consisting only of a high refractive index section, or the low refractive index section 14 may be configured of resin. Alternatively, a coating layer may be provided to cover the diffraction layer.

(3) In each embodiment, the diffractive optical element has been described using an example designed to diffract light having a wavelength of 850 nm. The present invention is not limited to this, and the present invention may be applied to a diffractive optical element that diffracts not only infrared light but also visible light or any other wavelength of light.

(4) In each embodiment, the light irradiation device has been described using an example designed to irradiate light with a wavelength of 850 nm. The light source is not limited to this, for example, the light source may emit light with a wavelength of 500 nm, and the light source may emit light of any wavelength, including not only infrared light but also visible light. It's okay.

(5) In each embodiment, the light irradiation device has been described using an example including one diffractive optical element 10. The structure is not limited to this, and a structure in which a plurality of diffractive optical elements are stacked may be used. In that case, a plurality of diffractive optical element wafers may be stacked on the light source wafer and then cut, or the diffractive optical element may be cut into individual pieces while forming a chamfer, and then combined with the light source. It's okay. When a plurality of such diffractive optical elements are stacked, the effects of the present application are even more effective.

(6) In each embodiment, the light source section 20 has been described by showing an example of a specific configuration including a light emitting element (light source) 21, a substrate 22, and a holder 24. The configuration of the light source section is not limited to this, and various known configurations can be applied as appropriate. For example, in the embodiment, the light emitting element (light source) 21 is mounted on the substrate 22, and there is a space between the light emitting element 21 and the holder 24, but this space is filled with resin or the like. The structure may be filled, or the function of the holder 24 may also be performed by filled resin (sealing material). Alternatively, the function of the substrate 22 may be included in the light emitting element wafer to provide a simpler configuration.
Furthermore, in the case of forming a chamfered portion on the diffractive optical element and dividing the diffractive optical element into individual pieces in advance, the form of the holder 24 is not limited to the structure of a simple wall portion as exemplified in the embodiment. Alternatively, the part that accommodates the diffractive optical element may be configured as a stepped part that is lowered one step. Further, the chamfered portion may be arranged facing the light source side. As for the position of the chamfered portion, an optimal arrangement can be selected as appropriate, assuming a direction in which the chamfered portion may be bent due to stress.
Furthermore, the explanation has been given using an example in which the uneven shape of the diffraction grating provided on the diffractive optical element is arranged on the output side (the side far from the light source), but the invention is not limited to this. It may be arranged toward the side (closer to the light source).
Alternatively, a structure in which a plurality of diffractive optical elements are stacked may be used.
Moreover, the specific structure and manufacturing method of the light source section are not limited to the configurations exemplified above, and may be appropriately replaced with known forms.

Note that the embodiments and modifications can be used in combination as appropriate, but detailed description will be omitted. Furthermore, the present invention is not limited to the embodiments described above.

1, 1B Light irradiation device 10 Diffractive optical element 11 High refractive index portion 11a-1 Level 1 stepped portion 11a-2 Level 2 stepped portion 11a-3 Level 3 stepped portion 11a-4 Level 4 stepped portion 11b Side wall portion 12 Base material 13 Adhesion layer 14 Low refractive index portion 14a Concave portion 14b Space 15 Diffraction layer 16 Mark 17 Unit cell 18 Chamfered portion 19 Guarantee function layer 20 Light source portion 21 Light emitting element 22 Substrate 23 Wiring 24 Holder 24a Top portion 60 Adhesive material 100 Diffractive optical element wafer 200 Light source Wafer 300, 401, 402, 403 original plate

Claims (7)

a light source and
a diffractive optical element having a rectangular unit cell arranged at a position to be irradiated with light from the light source and configured to form a plurality of diffraction gratings to obtain specific light distribution characteristics;
Equipped with
The diffractive optical element is configured by a plurality of unit cells arranged periodically, and the diffraction grating is formed up to an end of the diffractive optical element,
The plurality of unit cells all have the same configuration of the diffraction grating and have the same uneven shape,
In a boundary portion where the unit cells are adjacent to each other, the pattern of the diffraction grating is continuous,
The diffractive optical element includes a mark that is distinguishable from the diffraction grating, and
The pitch of the uneven shape of the mark is wider than the pitch of the pattern of the diffraction grating, where the width of a set of adjacent concave and convex portions of the uneven shape forming the mark is defined as a pitch. The light irradiation device according to claim 1 ,
the mark is placed overlapping a region where the diffraction grating is placed;
A light irradiation device characterized by: The light irradiation device according to claim 1 or 2 ,
The unit cell has a size that allows a plurality of unit cells to be arranged within an irradiation range of light emitted from the light source;
A light irradiation device characterized by: The light irradiation device according to any one of claims 1 to 3 ,
The diffraction grating has a pattern in which a boundary between a convex portion and a concave portion includes at least one of a curved line and a polygonal line connecting a plurality of line segments when viewed from the normal direction of the surface of the diffraction grating on which the uneven shape is formed. to have,
A light irradiation device characterized by: The light irradiation device according to any one of claims 1 to 4 ,
The diffractive optical element has a chamfered portion at least at an end on the side where the diffraction grating is formed;
A light irradiation device characterized by: The light irradiation device according to claim 5 ,
The diffractive optical element is
Equipped with a base material made of glass,
the chamfered portion is formed at least to a position reaching the base material;
A light irradiation device characterized by: The light irradiation device according to claim 5 or 6 ,
the chamfered portions are provided on each of both surfaces of the diffractive optical element;
A light irradiation device characterized by:

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