CN110869666A

CN110869666A - Lighting device

Info

Publication number: CN110869666A
Application number: CN201880046183.7A
Authority: CN
Inventors: 仓重牧夫; 西尾俊平
Original assignee: Dai Nippon Printing Co Ltd
Current assignee: Dai Nippon Printing Co Ltd
Priority date: 2017-07-25
Filing date: 2018-07-24
Publication date: 2020-03-06
Anticipated expiration: 2038-07-24
Also published as: JP6508580B1; JP7092086B2; WO2019022078A1; CN110869666B; JP2019133950A; JPWO2019022078A1

Abstract

The lighting device (10) comprises: a light source (15) that emits light; a diffractive optical element (40) that diffracts light emitted from the light source (15); and a projection optical system (50) that reflects or refracts the light diffracted by the diffractive optical element (40) toward the projection surface (S), wherein the projection optical system (50) directs one part of the 1 st-order diffracted light diffracted by the diffractive optical element (40) in a different direction from the other part of the 1 st-order diffracted light.

Description

Lighting device

Technical Field

The present disclosure relates to lighting devices.

Background

For example, as disclosed in patent document 1, an illumination device including a light source and a hologram element is known. In the vehicle lighting device disclosed in patent document 1, the hologram element diffracts light from the light source to project the light in a specific direction, thereby illuminating a projection surface such as a road surface.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2012 and 146621

Disclosure of Invention

Problems to be solved by the invention

However, when illumination is performed using an illumination device, it is sometimes desirable to project light in a plurality of directions and perform a plurality of illuminations simultaneously. If light can be projected in a plurality of directions, the projection surface can be divided into a plurality of regions by illuminating the projection surface with a plurality of line patterns extending in a plurality of directions, for example.

In view of the above, an object of the present disclosure is to provide an illumination device capable of projecting light in a plurality of directions.

Means for solving the problems

The lighting device of the embodiment of the present disclosure includes:

a light source that emits light;

a diffractive optical element that diffracts the light emitted from the light source; and

a projection optical system that reflects or refracts the light diffracted by the diffractive optical element toward a projection surface,

the projection optical system directs one part of the 1 st order diffracted light diffracted by the diffractive optical element and the other part thereof in different directions.

In the lighting device of the embodiment of the present disclosure, it is also possible,

the diffractive optical element has a 1 st element diffractive optical element that diffracts a part of the light emitted from the light source and a 2 nd element diffractive optical element that diffracts another part of the light emitted from the light source,

the projection optical system directs 1 st diffracted light, which is 1 st order diffracted light diffracted by the 1 st element diffractive optical element, and 2 nd diffracted light, which is 1 st order diffracted light diffracted by the 2 nd element diffractive optical element, in different directions.

In the lighting device according to the embodiment of the present disclosure, the projection optical system may be a reflection element or a prism.

In the illumination device according to the embodiment of the present disclosure, the projection optical system may include: a half mirror that reflects a part of the 1 st order diffracted light diffracted by the diffractive optical element and transmits the other part; and a reflection element that reflects the other part of the 1 st order diffracted light that has passed through the half mirror.

In the illumination device according to the embodiment of the present disclosure, the projection optical system may be a projection diffractive optical element that diffracts light diffracted by the diffractive optical element.

In the illumination device according to the embodiment of the present disclosure, the diffractive optical element may include: a 1 st element diffractive optical element that diffracts a part of the light emitted from the light source; and a 2 nd element diffractive optical element that diffracts another part of the light emitted from the light source,

the diffractive optical element for projection includes: a 1 st projection element diffractive optical element that diffracts 1 st diffracted light, which is the 1 st order diffracted light diffracted by the 1 st element diffractive optical element, so that the 1 st diffracted light is directed in a 1 st direction; and a 2 nd projection element diffraction optical element which diffracts a 2 nd diffraction light, the 2 nd diffraction light being a 1 st order diffraction light diffracted by the 2 nd element diffraction optical element, so that the 2 nd diffraction light is directed in a 2 nd direction different from the 1 st direction.

In addition, the illumination device of the embodiment of the present disclosure may further include a collimator lens disposed between the light source and the diffractive optical element along an optical path from the light source to the diffractive optical element.

In the illumination device according to the embodiment of the present disclosure, the projection optical system may change the traveling direction of a part of the 1 st order diffracted light diffracted by the diffractive optical element by an angle exceeding 90 °, and change the traveling direction of another part of the 1 st order diffracted light diffracted by the diffractive optical element by an angle exceeding 90 °.

In addition, the lighting device according to the embodiment of the present disclosure may be housed in a cylindrical housing.

In this case, the housing may be configured to be rotatable.

In addition, the lighting device according to the embodiment of the present disclosure may be rotatably supported.

In the illumination device according to the embodiment of the present disclosure, the projection optical system may be rotatably supported.

In the illumination device according to the embodiment of the present disclosure, the diffractive optical element may be rotatably supported.

In addition, the lighting device according to the embodiment of the present disclosure may further include:

a 1 st lens disposed between the diffractive optical element and the projection optical system along an optical path from the diffractive optical element to the projection optical system, and disposed apart from the diffractive optical element by a focal length of the 1 st lens;

a 2 nd lens which is disposed between the 1 st lens and the projection optical system along an optical path from the 1 st lens to the projection optical system, and which is disposed apart from the 1 st lens by a sum of a focal length of the 1 st lens and a focal length of the 2 nd lens; and

and a 0-order photomask disposed between the 1 st lens and the 2 nd lens along an optical path from the 1 st lens to the 2 nd lens, and configured to block 0-order light in the diffractive optical element.

and a higher order diffraction light mask which is disposed between the 1 st lens and the 2 nd lens along an optical path from the 1 st lens to the 2 nd lens and blocks higher order diffraction light in the diffractive optical element.

In addition, in the lighting device of the embodiment of the present disclosure, it is also possible,

the projection optical system reflects or refracts a part and another part of the 1 st order diffracted light diffracted by the diffractive optical element to respectively direct the 1 st illuminated region and the 2 nd illuminated region on the projection surface,

the 1 st illuminated region and the 2 nd illuminated region extend along a straight line as a whole. In this case, the 1 st illuminated region and the 2 nd illuminated region may extend on a straight line.

Effects of the invention

According to the present disclosure, a lighting device capable of projecting light to a plurality of directions may be provided.

Drawings

Fig. 1 is a view for explaining embodiment 1 of the present disclosure, and is a perspective view showing a lighting device.

Fig. 2 is a schematic diagram showing an example of the configuration of the lighting device of fig. 1.

Fig. 3 is a diagram for explaining a modification of the illumination device shown in fig. 2, and is a diagram showing the length of an area illuminated by the illumination device shown in fig. 2 and the length of an area illuminated by the illumination device that projects light in a single direction.

Fig. 4 is a view showing another modification of the lighting device shown in fig. 2.

Fig. 5 is a view showing still another modification of the lighting device shown in fig. 2.

Fig. 6 is a view showing still another modification of the lighting device shown in fig. 2.

Fig. 7 is a diagram showing still another modification of the lighting device shown in fig. 2.

Fig. 8 corresponds to fig. 2, and is a view showing still another modification of the lighting device shown in fig. 2.

Fig. 9 is a diagram showing a change in the illuminated region illuminated by the illumination device shown in fig. 8, and is a diagram of the illumination device and the projection surface shown in fig. 8 as viewed from above.

Fig. 10 corresponds to fig. 2, and is a view showing still another modification of the lighting device shown in fig. 2.

Fig. 11 corresponds to fig. 2, and is a view showing still another modification of the lighting device shown in fig. 2.

Fig. 12 corresponds to fig. 2, and is a schematic diagram illustrating an example of the configuration of the lighting device according to embodiment 2 of the present disclosure.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings attached to the present specification, the scale, the aspect ratio, and the like are appropriately changed and exaggerated from the viewpoint of physical objects for convenience of illustration and understanding.

The terms, lengths and angles used in the present specification, such as "parallel", "perpendicular" and "the same", as well as terms specifying the shapes, geometrical conditions and degrees thereof, are not limited to strict meanings and are interpreted to include ranges of degrees that can expect the same functions.

< embodiment 1>

First, embodiment 1 will be described with reference to fig. 1 and 2.

Fig. 1 is a perspective view showing an example of an illumination device 10 according to embodiment 1. Fig. 2 is a schematic diagram showing an example of the configuration of the illumination device 10 shown in fig. 1.

As shown in fig. 1, the illumination device 10 is installed on the floor or the bottom surface, and illuminates two different illumination target areas Z1 and Z2 with the installation surface as a projection surface S. More specifically, the lighting device 10 projects light in two different directions, and illuminates the 1 st illuminated region Z1 and the 2 nd illuminated region Z2 in a linear pattern. Such an illumination device 10 can be used, for example, when dividing the projection surface S. That is, the lighting device 10 can represent the boundary lines of the divided regions by the linear illuminated regions Z1 and Z2. The illumination device 10 may illuminate the illuminated areas Z1 and Z2 in any pattern other than a linear pattern, for example, in a pattern of a figure or a character. The illumination device 10 may illuminate the illumination target areas Z1 and Z2 in different patterns.

As shown in fig. 2, in embodiment 1, the lighting device 10 includes: a light source 15 that emits light; a diffractive optical element 40 that diffracts light emitted from the light source 15; and a projection optical system 50 that reflects or refracts the light diffracted by the diffractive optical element 40 toward the projection surface S. In the example shown in fig. 2, the illumination device 10 further includes a shaping optical system 30, and the shaping optical system 30 includes a collimator lens 32 between the light source 15 and the diffractive optical element 40.

As can be seen from fig. 1 and 2, the illumination device 10 is housed in a cylindrical housing 60 and can stand on the projection surface S. In the illustrated example, the light source 15, the diffractive optical element 40, and the projection optical system 50 are arranged in a substantially vertical direction with respect to the projection surface S in the housing 60. The housing 60 is provided with an opening 61 through which light reflected or refracted by the projection optical system 50 passes. Hereinafter, each constituent element of the illumination device 10 will be described in order.

The light source 15 may use various types of light sources. As an example, a light source that emits coherent light, for example, a laser light source may be used as the light source 15. The coherent light emitted from the light source 15 has excellent straightness, and is suitable as light for illuminating the illuminated regions Z1 and Z2 with high accuracy. In the example shown in fig. 2, the lighting device 10 has a single light source 15, but may have a plurality of light sources 15.

Next, the entire optical system 30 will be explained. The shaping optical system 30 is disposed between the light source 15 and the diffractive optical element 40 along an optical path from the light source 15 to the diffractive optical element 40. The shaping optical system 30 shapes the light emitted from the light source 15. In other words, the shaping optical system 30 shapes the shape of the light emitted from the light source 15 in a cross section perpendicular to the optical axis x and the three-dimensional shape of the light flux of the light. In the illustrated example, the shaping optical system 30 shapes the light emitted from the light source 15 into a widened parallel light beam. As shown in fig. 2, the shaping optical system 30 has a lens 31 and a collimator lens 32 in this order along the optical path of the light emitted from the light source 15. The lens 31 shapes the light emitted from the light source 15 into a divergent light beam. The collimator lens 32 reshapes the diverging light beam generated by the lens 31 into a parallel light beam. In addition, when the illumination device 10 includes a plurality of light sources, a plurality of shaping optical systems may be provided corresponding to the plurality of light sources, respectively.

Next, the diffractive optical element 40 will be explained. The diffractive optical element 40 is an element that generates a diffractive effect on the light emitted from the light source 15. The illustrated diffractive optical element 40 diffracts light from the light source 15 and directs the light toward the projection optical system 50.

In the illustrated example, the diffractive optical element 40 includes a 1 st element diffractive optical element 41 and a 2 nd element diffractive optical element 42. The 1 st element diffractive optical element 41 diffracts a part of the light from the collimator lens 32 to direct the light toward the projection optical system 50. The 2 nd element diffractive optical element 42 diffracts another part of the light from the collimator lens 32 and directs the diffracted light to the projection optical system 50.

As an example, each of the elemental diffraction optical elements 41 and 42 is configured as a hologram recording medium on which an interference fringe pattern is recorded. By performing various adjustments to the interference fringe pattern, the traveling direction of the light diffracted by the element diffractive optical elements 41 and 42, in other words, the traveling direction of the light diffused by the element diffractive optical elements 41 and 42, can be controlled.

Each of the element diffractive optical elements 41 and 42 can be produced by using, for example, scattered light from a scattering plate as an actual object as object light. More specifically, when the hologram photosensitive material as the base of the element diffraction optical elements 41 and 42 is irradiated with the reference light and the object light, which are coherent light beams having interference with each other, interference fringes due to interference of these light beams are formed on the hologram photosensitive material, and the element diffraction optical elements 41 and 42 are manufactured. As the reference light, laser light which is coherent light is used, and as the object light, for example, scattered light from an isotropic scattering plate which can be obtained at low cost is used.

By irradiating the element diffractive optical elements 41 and 42 with laser light so that the optical path of the reference light used when the element diffractive optical elements 41 and 42 are manufactured travels in the reverse direction, a reproduced image of the scattering plate is generated at the position where the scattering plate is disposed, which is the basis of the object light used when the element diffractive optical elements 41 and 42 are manufactured. If the scattering plate, which is the base of the object light used in the production of the element diffractive optical elements 41 and 42, performs uniform surface scattering, the reproduced image of the scattering plate obtained by the element diffractive optical elements 41 and 42 also becomes uniform surface illumination.

The complex interference fringe patterns formed on the elemental diffraction optical elements 41 and 42 are not formed using actual object light and reference light, but may be designed using a predetermined wavelength and incidence direction of reproduction illumination light, and using a computer based on the shape, position, and the like of an image to be reproduced. The element diffraction optical elements 41 and 42 thus obtained are also called Computer Generated Holograms (CGH).

Further, fourier transform holograms having the same diffusion angle characteristics at each point on the elemental diffraction optical elements 41 and 42 may be formed by computer synthesis.

The element diffractive optical elements 41 and 42 may be, in specific embodiments, volume hologram recording media using a photopolymer, volume hologram recording media of a type that performs recording using a photosensitive medium containing a silver salt material, or hologram recording media of an embossed type (embossed type). The element diffraction optical elements 41 and 42 may be transmissive or reflective.

In addition, when the illumination device 10 includes a plurality of light sources, a plurality of diffractive optical elements may be provided corresponding to the plurality of light sources.

The projection optical system 50 reflects or refracts the light diffracted by the diffractive optical element 40 toward a projection surface S (an installation surface in the illustrated example). More specifically, the projection optical system 50 directs the 1 st order diffracted light (hereinafter also referred to as "1 st diffracted light") L11 diffracted by the 1 st element diffractive optical element 41 and the 1 st order diffracted light (hereinafter also referred to as "2 nd diffracted light") L12 diffracted by the 2 nd element diffractive optical element 42 in different directions. In the element diffractive optical elements 41 and 42 such as hologram elements, higher-order diffracted light of 2 orders or more (hereinafter also referred to as "higher-order diffracted light") is generated as diffracted light in addition to the 1-order diffracted light L11 and L12. The projection optical system 50 directs at least 1 st-order diffracted lights L11, L12 among diffracted lights entering the projection optical system 50 in different directions from each other.

In the illustrated example, the projection optical system 50 is a reflection element having a reflection surface that reflects light. At least the reflection surface of the projection optical system 50 is made of a material having a high reflectance, such as metal. In particular, in the illustrated example, at least the reflection surface of the projection optical system 50 is made of silver and has a specular reflection function.

As described above, the projection optical system 50 directs the 1 st diffracted light L11 diffracted by the 1 st element diffractive optical element 41 and the 2 nd diffracted light L12 diffracted by the 2 nd element diffractive optical element 42 in different directions. In the example shown in fig. 2, the projection optical system 50 is configured as a so-called polygon mirror having a plurality of reflection surfaces. More specifically, the projection optical system 50 has a triangular prism shape as a whole, and two side surfaces of three side surfaces thereof form reflection surfaces. One of the two reflection surfaces is the 1 st reflection surface 51 on which the 1 st diffracted light L11 enters, and directs the 1 st diffracted light L11 in the 1 st direction. The other reflecting surface is the 2 nd reflecting surface 52 on which the 2 nd diffracted light L12 enters, and directs the 2 nd diffracted light L12 in the 2 nd direction different from the 1 st direction. As the projection optical system 50 capable of directing the 1 st diffracted light L11 and the 2 nd diffracted light L12 in different directions, various mirrors such as a concave mirror, a convex mirror, a plane mirror, and a prism may be used in addition to the polygon mirror.

In the example shown in fig. 2, the orientation of the 1 st reflecting surface 51 is set so that the traveling direction of the 1 st diffracted light L11 changes at an angle exceeding 90 ° and the 1 st diffracted light L11 is directed to the 1 st illuminated area Z1 on the projection surface S. The orientation of the 2 nd reflecting surface 52 is set so that the traveling direction of the 2 nd diffracted light L12 changes at an angle exceeding 90 ° and the 2 nd diffracted light L12 is directed to the 2 nd illuminated area Z2 on the projection surface S.

Next, the operation of the illumination device 10 configured as described above will be described.

The light emitted from the light source 15 is first incident on the shaping optical system 30. In the shaping optical system 30, the light emitted from the light source 15 is amplified. That is, the shaping optical system 30 shapes the light from the light source 15 so as to expand the area occupied by the light in a cross section perpendicular to the optical axis x. In the illustrated example, the shaping optical system 30 has a lens 31 and a collimator lens 32. As shown in fig. 2, the lens 31 of the shaping optical system 30 disperses the light emitted from the light source 15 and converts the light into a divergent light beam. Then, the collimator lens 32 of the shaping optical system 30 collimates the divergent light beam into a parallel light beam.

The light shaped by the shaping optical system 30 is then directed toward the diffractive optical element 40. The element diffractive optical elements 41 and 42 of the diffractive optical element 40 record interference fringes corresponding to the center wavelength of the light emitted from the light source 15, and can efficiently diffract light incident from a certain direction in a desired direction. In the illustrated example, the 1 st element diffractive optical element 41 diffracts a part of the light emitted from the light source 15 and diffuses the diffracted light toward the projection optical system 50. The 2 nd element diffractive optical element 42 diffracts another part of the light emitted from the light source 15 and diffuses the diffracted light toward the projection optical system 50.

The light incident on the reflection surfaces 51 and 52 of the projection optical system 50 is reflected, and the traveling direction thereof is changed. In particular, the 1 st diffracted light L11 incident on the 1 st reflecting surface 51 is reflected, and its traveling direction is changed at an angle exceeding 90 °. Then, the 1 st diffracted light L11 reflected by the 1 st reflecting surface 51 passes through the opening 61 provided in the cylindrical case 60 and enters the 1 st illuminated area Z1 on the projection surface S. The 2 nd diffracted light L12 incident on the 2 nd reflecting surface 52 is reflected, and its traveling direction is changed at an angle exceeding 90 °. The 2 nd diffracted light L12 reflected by the 2 nd reflecting surface 52 is directed in a direction different from the 1 st diffracted light L11 reflected by the 1 st reflecting surface 51. Then, the 2 nd diffracted light L12 passes through the opening 61 provided in the cylindrical case 60, and enters the 2 nd illuminated area Z2 on the projection surface S, which is different from the 1 st illuminated area Z1. In the illustrated example, the 1 st illuminated region Z1 and the 2 nd illuminated region Z2 are illuminated in a linear pattern extending in different directions from the lighting device 10.

According to embodiment 1 as described above, the lighting device 10 includes: a light source 15 that emits light; a diffractive optical element 40 that diffracts light emitted from the light source 15; and a projection optical system 50 that reflects or refracts the light diffracted by the diffractive optical element 40 toward the projection surface S. Then, the projection optical system 50 directs a part L11 of the 1 st order diffracted light diffracted by the diffractive optical element 40 and another part L12 in different directions.

Such a lighting device 10 can illuminate a plurality of illuminated areas Z1, Z2 by projecting light in a plurality of directions.

In embodiment 1, the diffractive optical element 40 includes: a 1 st element diffractive optical element 41 that diffracts a part of the light emitted from the light source 15; and a 2 nd element diffractive optical element 42 that diffracts another part of the light emitted from the light source 15. Then, the projection optical system 50 directs the 1 st diffracted light, which is the 1 st order diffracted light diffracted by the 1 st element diffractive optical element 41, and the 2 nd diffracted light L12, which is the 1 st order diffracted light diffracted by the 2 nd element diffractive optical element 42, in different directions. According to the lighting device 10, each of the plurality of illuminated regions Z1, Z2 can be illuminated easily with a desired pattern and with high accuracy.

In embodiment 1, the projection optical system 50 is a reflection element or a prism. In this case, the projection optical system 50 that reflects or refracts the 1 st diffracted light L11 and the 2 nd diffracted light L12 to direct them in different directions can be easily realized.

In addition, in embodiment 1, a collimator lens 32 is further provided, and the collimator lens 32 is disposed between the light source 15 and the diffractive optical element 40 along the optical path from the light source 15 to the diffractive optical element 40. Thus, since the collimated light is incident on the diffractive optical element 40, the 1 st diffracted light L11 and the 2 nd diffracted light L12 can be easily diffracted in a desired direction with high accuracy by the diffractive optical element 40.

In embodiment 1, the projection optical system 50 changes the traveling direction of a part L11 of the 1 st order diffracted light diffracted by the diffractive optical element 40 at an angle exceeding 90 °, and changes the traveling direction of another part L12 of the 1 st order diffracted light diffracted by the diffractive optical element 40 at an angle exceeding 90 °. In this case, for example, as shown in fig. 1 and 2, the illumination device 10 can illuminate the installation surface as the projection surface S.

In embodiment 1, the lighting device 10 is housed in a cylindrical case 60. In this case, the illumination device 10 can be easily erected on the projection surface S. Further, as shown in fig. 4 described later, it is easy to install a part of the device under the ground, the floor, or the water.

In addition, various modifications can be made to embodiment 1. Hereinafter, several modifications will be described with reference to the drawings. In the following description and the drawings used in the following description, the same reference numerals as those used for corresponding portions in embodiment 1 are used for portions that can be configured in the same manner as in embodiment 1, and redundant description is omitted.

< modification 1>

In the above-described embodiment 1, for example, a case where the 1 st illuminated region Z1 and the 2 nd illuminated region Z2 extending on a straight line are illuminated by the illumination device 10 is considered. In this case, considering that the closer to the illumination device 10 the areas Z1 and Z2 are, the brighter the pattern illumination becomes, the better the visibility is, and the farther from the illumination device 10 the projected pattern is blurred and darkly illuminated, and the poorer the visibility is, the areas illuminated with the light L11 illuminating the illuminated area Z1 and the light L12 illuminating the illuminated area Z2 with the clear and bright pattern visibility (hence, falling) are the areas from the point E11 to the point E12 and from the point E21 to the point E22 shown in fig. 3. Therefore, the lighting device 10 can be used to illuminate a region having a length L10 from the point E12 on one side of the lighting device 10 to the point E22 on the other side thereof with a clear and bright pattern with good visibility.

In contrast, when the illumination target area Z500 is illuminated by the illumination device 500 that projects light in only one direction using a light source that emits a radiation beam of light of the same degree as the light source 15 of the illumination device 10, if it is considered that the closer to the illumination device 500 in the illumination target area Z500, the brighter pattern illumination is better in visibility, the farther from the illumination device 500, the more blurred and darker the projected pattern is, and the poorer in visibility, the area illuminated by the light L500 illuminating the illumination target area Z500 with a bright and clear pattern is the area having the length L500 from the point E51 to the point E52 shown in fig. 3.

In this way, the lighting device 10 can be used to illuminate the region having the length L10 from the point E12 on one side to the point E22 on the other side of the lighting device 10 with a clear and bright pattern with good visibility, whereas the region that can be illuminated with the clear and bright pattern by the lighting device 500 is only the region having the length L500 from the point E51 on one side to the point E52 of the lighting device 500. Generally, the length L10 is significantly longer than the length L500. That is, the illumination device 10 can be used to illuminate a longer area with a clear and bright pattern with good visibility than the illumination device 500. In other words, when an area having a length L10 longer than the length L500 is illuminated, if the illumination device 10 is disposed at an intermediate point of the area and light is projected from the intermediate point, the points E12 and E22 farthest from the illumination device 10 can be illuminated with a clear and bright pattern with good visibility in the area.

In the description of modification 1, the case where the illumination device 10 illuminates the 1 st illumination target area Z1 and the 2 nd illumination target area Z2 extending on a straight line has been described, but the invention is not limited thereto. That is, the 1 st illuminated region Z1 and the 2 nd illuminated region Z2 may not extend on a strictly straight line. The 1 st illuminated region Z1 and the 2 nd illuminated region Z2 may extend in directions intersecting each other, as in a region Z1b and a region Z2a shown in fig. 9, for example. Even in this case, if the 1 st illuminated region Z1 and the 2 nd illuminated region Z2 as a whole extend along a straight line, the same effect as in the case where the 1 st illuminated region Z1 and the 2 nd illuminated region Z2 extend on a straight line can be obtained.

According to the modification 1 described above, the projection optical system 50 reflects or refracts the part L11 and the other part L12 of the 1 st order diffracted light diffracted by the diffractive optical element 40 to direct the 1 st illuminated region Z1 and the 2 nd illuminated region Z2, respectively, on the projection surface S. Further, the 1 st illuminated region Z1 and the 2 nd illuminated region Z2 extend along a straight line as a whole. In particular, in the illustrated example, the 1 st illuminated region Z1 and the 2 nd illuminated region Z2 extend on a straight line. In this case, the lighting device 10 can illuminate a region having a length L10 from the point E12 on one side to the point E22 on the other side of the lighting device 10 with a clear and bright pattern with good visibility (and thus beautiful appearance), and the length L10 is significantly longer than the length L500 of a region that can illuminate only one direction with a clear and bright pattern with good visibility by using a light source that emits a radiation beam of the same degree as that of the light source 15 of the lighting device 10.

< modification 2>

In the above-described embodiment 1, the case where the diffractive optical element 40 has the two element diffractive optical elements 41 and 42 and the illumination device 10 illuminates the two illumination target areas Z1 and Z2 has been described, but the present invention is not limited thereto. For example, as shown in fig. 4, the diffractive optical element may have three or more element diffractive optical elements. In this case, the illumination device may project light in three or more directions to illuminate three or more illuminated areas.

The illumination device 100 shown in fig. 4 projects light in three directions to illuminate three illuminated areas Z1, Z2, and Z3. In the illumination device 100 shown in fig. 4, the diffractive optical element 140 includes three element diffractive optical elements 41, 42, and 43, and the projection optical system 150 includes three

reflection surfaces

51, 52, and 53. The other structure is substantially the same as the lighting device 10 shown in fig. 2. In fig. 3, the illustration of the case 60 is omitted for easy understanding.

The diffractive optical element 140 includes a 3 rd element diffractive optical element 43 in addition to the 1 st element diffractive optical element 41 and the 2 nd element diffractive optical element 42. The 3 rd element diffractive optical element 43 is configured as a hologram recording medium on which an interference fringe pattern is recorded, for example, like the other element diffractive optical elements 41 and 42. In the diffractive optical element 140 shown in fig. 4, the 1 st element diffractive optical element 41 diffracts a part of the light from the collimator lens 32 toward the projection optical system 150. The 2 nd element diffractive optical element 42 diffracts another part of the light to direct the light toward the projection optical system 150. The 3 rd element diffractive optical element 43 diffracts another part of the light to direct the light toward the projection optical system 150.

The projection optical system 150 has a 3 rd reflection surface 53 in addition to the 1 st reflection surface 51 and the 2 nd reflection surface 52. In the example shown in fig. 4, the projection optical system 150 has a triangular pyramid shape. Three surfaces other than the bottom surface have a reflection function, and reflection surfaces 51, 52, and 53 are formed, respectively. The 3 rd reflection surface 53 directs the 1 st order diffracted light (hereinafter also referred to as "3 rd diffracted light") L13 diffracted by the 3 rd element diffractive optical element 43 to the 3 rd direction different from both the 1 st diffracted light L11 and the 2 nd diffracted light L12. The 3 rd reflection surface 53 changes the traveling direction of the 3 rd diffracted light L13 at an angle exceeding 90 °, and directs the 3 rd diffracted light L13 to the 3 rd illuminated area Z3 on the projection surface S. The shape of the projection optical system 150 may be a pyramid shape, a cone shape, or other various shapes.

< modification 3 >

In embodiment 1 described above, the case where the illumination device 10 is provided on the projection surface S is explained. However, for example, when the lighting device 10 is intended to be small, a part of the lighting device 10 may be disposed below the projection surface S, that is, under the ground or below, as shown in fig. 5. When the water surface is the projection surface S, a part of the lighting device 10 may be disposed in the water.

< modification 4>

In embodiment 1, the case where the lighting device 10 is installed on the floor surface or the bottom surface is described, but the present invention is not limited thereto. The illumination device 10 can be used in various fields, for example, as an illumination device for a mobile body such as a vehicle or a ship.

In the example shown in fig. 6, the illumination device 10 is provided in the vehicle C, and projects light in both the right front lower direction of the vehicle C and the left front lower direction of the vehicle C. Then, the lighting device 10 illuminates the 1 st illuminated region Z1 located in the right front of the vehicle C and the 2 nd illuminated region Z2 located in the left front.

In the example shown in fig. 7, the illumination device 10 is provided on the vehicle C, and projects light in two directions which are forward and downward of the vehicle C but which form different angles with respect to the floor surface or the bottom surface as the projection surface S. The lighting device 10 illuminates an illuminated area in the near field and an illuminated area in the far field of the vehicle C.

The illumination device 10 shown in fig. 6 and 7 includes a light source 15, a shaping optical system 30, a diffractive optical element 40 including a plurality of element diffractive optical elements, and a projection optical system 50, as in the above-described illumination device. The projection optical system 50 is formed by a prism. The prism has a 1 st prism surface 51a for changing the optical path of the 1 st diffracted light L11 by refraction; and a 2 nd prism surface 52a inclined with respect to the 1 st prism surface 51a, for deflecting the optical path of the 2 nd diffracted light L12 in a direction different from the optical path of the 1 st diffracted light L11.

< modification 5>

In the above-described embodiment 1 and the above-described modification, the case where the projection optical system is a reflection element or a prism has been described, but the present invention is not limited thereto. The projection optical system may be a projection diffractive optical element that diffracts the 1 st order diffracted light diffracted by the diffractive optical element 40.

Modification 5 will be described below with reference to fig. 8. The illumination device 200 shown in fig. 8 differs from the illumination device 10 shown in fig. 2 in that the projection optical system is a projection diffractive optical element 250.

As an example, the diffractive optical element 250 for projection is configured as a hologram recording medium on which an interference fringe pattern is recorded. By performing various adjustments to the interference fringe pattern, the traveling direction of the light diffracted by the projection diffractive optical element 250, in other words, the traveling direction of the light diffused by the projection diffractive optical element 250 can be controlled. The projection diffractive optical element 250 can be manufactured in the same manner as the element diffractive optical elements 41 and 42 of the diffractive optical element 40.

In the example shown in fig. 8, the diffractive optical element 250 for projection includes: a 1 st projection diffraction region 251 into which a 1 st diffracted light beam L11 is incident, the 1 st diffracted light beam L11 being a 1 st order diffracted light beam diffracted by the 1 st element diffractive optical element 41; and a 2 nd projection diffraction region 252 into which a 2 nd diffracted light L12 is incident, the 2 nd diffracted light L12 being 1 st order diffracted light diffracted by the 2 nd element diffractive optical element 42. The projection diffractive optical element 250 directs the 1 st diffracted light L11 from the 1 st element diffractive optical element 41 in a direction corresponding to the diffraction characteristics in the 1 st projection diffractive region 251. The projection diffractive optical element 250 directs the 2 nd diffracted light L12 from the 2 nd element diffractive optical element 42 in a direction corresponding to the diffraction characteristic in the 2 nd projection diffractive region 252.

In the illustrated example, the 1 st projection diffraction region 251 diffracts the 1 st diffracted light L11 from the 1 st element diffractive optical element 41 toward the 1 st illuminated region Z1. The 2 nd projection diffraction region 252 diffracts the 2 nd diffracted light L12 from the 2 nd element diffractive optical element 42 toward the 2 nd illuminated region Z2.

When such a diffractive optical element for projection 250 is used as the projection optical system, the illuminated regions Z1 and Z2 illuminated by the illumination device 200 are regions corresponding to the diffraction characteristics of the diffractive optical element for projection 250. Therefore, by replacing the projection diffractive optical element 250 with another projection diffractive optical element having a different diffraction characteristic from the projection diffractive optical element 250, the illuminated regions Z1 and Z2 illuminated by the illumination device 200 can be changed from the illuminated regions Z1a and Z2a shown in fig. 9 to the illuminated regions Z1b and Z2b, for example.

As described above, according to modification 5, the projection optical system 250 is a diffractive optical element for projection that diffracts the light beams L11 and L12 diffracted by the diffractive optical element 40. Thus, by replacing the projection diffractive optical element 250 with another projection diffractive optical element having a different diffraction characteristic from the projection diffractive optical element 250, the illuminated regions Z1, Z2 illuminated by the illumination device 200 can be changed.

< modification 6>

In the modification 5, the case where the 1 st projection diffraction region 251 and the 2 nd projection diffraction region 252 of the projection diffractive optical element 250 are integrally formed was described, but the present invention is not limited thereto.

In the example shown in fig. 10, the 1 st projection diffraction region 251 and the 2 nd projection diffraction region 252 of the projection diffractive optical element 250 are formed as separate bodies. More specifically, the diffractive optical element 250 for projection includes: a 1 st-order-of-projection-use element diffractive optical element 253 that allows the 1 st-order diffracted light diffracted by the 1 st-order-of-element diffractive optical element 41 to enter; and a 2 nd projecting element diffractive optical element 254 for allowing the 1 st order diffracted light diffracted by the 2 nd element diffractive optical element 42 to enter. The 1 st projecting element diffractive optical element 253 diffracts the 1 st diffracted light L11 toward the 1 st direction, more specifically, the 1 st illuminated area Z1, and the 1 st diffracted light L11 is the 1 st order diffracted light from the 1 st element diffractive optical element 41. The 2 nd projecting element diffractive optical element 254 diffracts the 2 nd diffracted light L12 toward the 2 nd direction different from the 1 st direction, more specifically, the 2 nd illuminated region Z2, and the 2 nd diffracted light L12 is the 1 st order diffracted light from the 2 nd element diffractive optical element 42.

When such a projection diffractive optical element 250 is used as the projection optical system, by replacing one of the 1 st and 2 nd projection element diffractive optical elements 253 and 254 with another projection element diffractive optical element having a diffraction characteristic different from that of the projection element diffractive optical elements 253 and 254, only one of the 1 st and 2 nd illuminated regions Z1 and Z2 can be changed from the illuminated region Z1a to the illuminated region Z1b shown in fig. 9, or from the illuminated region Z2a to the illuminated region Z2b, for example.

As described above, according to modification 6, the diffractive optical element 40 includes: a 1 st element diffractive optical element 41 that diffracts a part of the light emitted from the light source 15; and a 2 nd element diffractive optical element 41 that diffracts another part of the light emitted from the light source 15. The diffractive optical element 250 for projection includes: a 1 st-projection element diffractive optical element 253 that diffracts the 1 st diffracted light L11 to direct the 1 st direction, the 1 st-order diffracted light L11 being diffracted by the 1 st-element diffractive optical element 41; and a 2 nd projecting element diffractive optical element 254 that diffracts a 2 nd diffracted light L12 to direct the 2 nd direction different from the 1 st direction, the 2 nd diffracted light L12 being a 1 st order diffracted light diffracted by the 2 nd element diffractive optical element 42. Thus, by replacing one of the 1 st and 2 nd projection element diffractive optical elements 253 and 254 with another projection element diffractive optical element having a different diffraction characteristic from the projection element diffractive optical elements 253 and 254, only one of the 1 st and 2 nd illuminated regions Z1 and Z2 can be changed.

< modification 7>

In embodiment 1 and modifications 1 to 6, the case where the diffractive optical element 40 includes a plurality of elemental diffractive optical elements has been described, but the present invention is not limited thereto. The diffractive optical element 40 may be constituted by a single element diffractive optical element.

Modification 7 will be described below with reference to fig. 11. The lighting device 300 shown in fig. 11 is different from the lighting device shown in fig. 2 in that the diffractive optical element 40 is formed of a single element diffractive optical element. Further, the projection optical system 350 differs in that it includes a half mirror 351 and a reflection element 352.

In the example shown in fig. 11, the diffractive optical element 40 diffracts all of the light emitted from the light source 15.

The half mirror 351 and the reflection element 352 of the projection optical system 350 are disposed on the optical path of the 1 st order diffracted light L1 diffracted by the diffractive optical element 40. The half mirror 351 is disposed between the diffractive optical element 40 and the reflection element 352 along an optical path from the diffractive optical element 40 to the reflection element 352.

The half mirror 351 reflects a part L11 of the 1 st order diffracted light L1 diffracted by the diffractive optical element 340 and transmits the other part L12 in the 1 st direction. The reflection element 352 reflects the other part L12 of the 1 st order diffracted light L1 transmitted through the half mirror 351 in the 2 nd direction. In the illustrated example, the light L11 reflected by the half mirror 351 is directed to the 1 st illuminated region Z1, and the light L12 reflected by the reflecting element 352 is directed to the 2 nd illuminated region Z2.

With such an illumination device 300, it is also possible to illuminate the plurality of illuminated areas Z1 and Z2 by directing the light emitted from the light source 15 in a plurality of directions. In the illustrated example, the diffractive optical element 40 is formed of a single element diffractive optical element, but is not limited thereto. Similarly to the example shown in fig. 2, the diffractive optical element 40 may include a plurality of element diffractive optical elements 41 and 42.

As described above, according to modification 7, the projection optical system 350 includes: a half mirror 351 that reflects a part L11 of the 1 st order diffracted light L1 diffracted by the diffractive optical element 40 and transmits the other part L12; and a reflection element 352 that reflects the other part L12 of the 1 st order diffracted light L1 transmitted through the half mirror 351. In the illumination device 300, the projection optical system 350 directs a part L11 and another part L12 of the 1 st order diffracted light L1 diffracted by the diffractive optical element 40 in different directions. Therefore, the illumination device 300 can illuminate the plurality of illuminated areas Z1 and Z2 by projecting light in a plurality of directions.

< modification 8>

In the above-described modifications 5 and 6, the case where the illumination target areas Z1 and Z2 are moved by replacing a part or all of the projection diffractive optical element 250 has been described, but the present invention is not limited to this. For example, the housing 60 housing the

lighting devices

10, 100, 200, and 300 may be placed on a rotatable base or the like and may be rotatably disposed, and the illuminated areas Z1, Z2, and Z3 may be moved by rotating the housing 60 together with the

lighting devices

10, 100, 200, and 300. Alternatively, the

illumination devices

10, 100, 200, and 300 in the housing 60 may be rotatably supported, and the illumination target areas Z1, Z2, and Z3 may be moved by rotating the

illumination devices

10, 100, 200, and 300. Alternatively, the diffractive

optical elements

40 and 140 may be rotatably supported, and the illumination areas Z1, Z2, and Z3 may be moved by rotating the diffractive

optical elements

40 and 140. Alternatively, the projection

optical systems

50, 150, 250, and 350 may be rotatably supported, and the illumination areas Z1, Z2, and Z3 may be moved by rotating the projection

optical systems

50, 150, 250, and 350. Alternatively, the diffractive

optical elements

40 and 140 and the projection

optical systems

50, 150, 250, and 350 together with the diffractive

optical elements

40 and 140.

< embodiment 2>

Next, embodiment 2 will be described with reference to fig. 12. In the following description and the drawings used in the following description, the same reference numerals as those used for corresponding portions in embodiment 1 are used for portions that can be configured in the same manner as in embodiment 1, and redundant description is omitted.

First, in the illumination device shown in fig. 1 and 2, a part of light from the light source is transmitted through the diffractive optical element without being diffracted by the diffractive optical element, and becomes so-called 0-order light. When such 0-order light is reflected or refracted by the projection optical system, there is a possibility that a safety problem such as entering the eyes of the observer may arise. When 0-level light enters the illuminated region, abnormal regions such as a dot region, a linear region, and a planar region, which have a brightness (luminance) that increases sharply compared with the surroundings, are generated in the illuminated region.

As described above, in an element diffraction optical element such as a hologram element, high-order diffracted light of 2 orders or more is generated as diffracted light in addition to 1-order diffracted light. When the higher order diffracted light is reflected or refracted by the projection optical system, there is a possibility that a problem in safety such as entering the eyes of the observer may arise. Further, when the high-order diffracted light is projected onto the projection plane, there is a problem that the region other than the illuminated region is also illuminated, and it is difficult to recognize the illuminated region.

In order to solve such a problem, in embodiment 2, a contrivance is made to prevent the 0 th order light and the high order diffracted light from entering the projection optical system. The lighting device 400 according to embodiment 2 will be described in more detail below with reference to fig. 12.

The illumination device 400 shown in fig. 12 is different from the illumination device 10 shown in fig. 1 only in that the 1 st lens 71, the 2 nd lens 72, the 0 th order photomask 81, and the high order diffraction photomask 82 are disposed between the diffractive optical element 40 and the projection optical system 50, and the other configuration is substantially the same as that of the illumination device 10 shown in fig. 1 and 2.

The 1 st lens 71 and the 2 nd lens 72 are disposed between the diffractive optical element 40 and the projection optical system 50 along an optical path from the diffractive optical element 40 to the projection optical system 50. More specifically, the diffractive optical element 40, the projection optical system 50, the 1 st lens 71, and the 2 nd lens 72 are arranged as follows.

The 1 st lens 71 is disposed between the diffractive optical element 40 and the projection optical system 50 along the optical path from the diffractive optical element 40 to the projection optical system 50, at a distance f1 from the diffractive optical element 40 by the focal length f1 of the 1 st lens 71. In addition, the 2 nd lens 72 is disposed between the 1 st lens 71 and the projection optical system 50 along the optical path from the 1 st lens 71 to the projection optical system 50. The 2 nd lens 72 and the 1 st lens 71 are disposed apart from each other by the sum of the focal length f1 of the 1 st lens 71 and the focal length f2 of the 2 nd lens 72. In addition, the distance between the 2 nd lens 72 and the projection optical system 50 is not particularly limited. In the example shown in fig. 12, the 2 nd lens 72 is disposed at a distance f2 of the 2 nd lens 72 from the incident positions of the 1 st diffracted light L11 and the 2 nd diffracted light L12 in the projection optical system 50, but the distance between the 2 nd lens 72 and the projection optical system 50 may be larger than the focal length f2 or smaller than the focal length f 2. In the example shown in fig. 12, the 1 st lens 71, the 2 nd lens 72, and the diffractive optical element 40 form a 4f optical system.

The 1 st lens 71 directs the 0 th order light L01 transmitted through the 1 st element diffractive optical element 41 and the 0 th order light L02 transmitted through the 2 nd element diffractive optical element 42 to the point a on the focal plane P of the 1 st lens 71. Further, the 1 st lens 71 changes the traveling direction of the 1 st order diffracted light (1 st diffracted light) L11 and the higher order diffracted light L21 in the 1 st element diffractive optical element 41 to a direction parallel to the traveling direction of the 0 th order light L01 passing through the 1 st lens 71. Further, the 1 st lens 71 changes the traveling direction of the 1 st order diffracted light (2 nd diffracted light) L12 and the higher order diffracted light L22 in the 2 nd element diffractive optical element 42 to a direction parallel to the traveling direction of the 0 th order light L02 passing through the 1 st lens 71. As a result, as shown in fig. 12, the incident positions of the 0 th order light L01, L02, 1 st order diffracted light L11, L12, and higher order diffracted light L21, L22 on the focal plane P are respectively focused on the areas around the point a and the point a, and the areas outside the area.

The 2 nd lens 72 converges light passing through a region between a 0 th order photomask 81 and a higher order diffraction photomask 82, which will be described later, that is, the 1 st diffracted light L11 and the 2 nd diffracted light L12 toward the projection optical system 50, respectively.

The 0-order photomask 81 is disposed between the 1 st lens 71 and the 2 nd lens 72 along the optical path from the 1 st lens 71 to the 2 nd lens 72. The 0-order photomask 81 is disposed on the focal plane P of the 1 st lens 71 so as to be spaced apart from the 1 st lens 71 by the focal length f1 of the 1 st lens 71. The 0-order photomask 81 is disposed at a position that overlaps the position a of the focal plane P where the 0-order light L01, L02 enters but does not overlap the position where the 1-order diffracted light L11, L12 and the higher-order diffracted light L21, L22 enter. As a result, the 0-order photomask 81 can block only the 0-order light L01 and L02 among the diffracted lights in the diffractive optical element 40.

The high-order diffraction light mask 82 is also arranged on the same surface as the 0-order photomask 81. That is, the higher order diffraction light mask 82 is disposed between the 1 st lens 71 and the 2 nd lens 72 along the optical path from the 1 st lens 71 to the 2 nd lens 72. The high-order diffraction light mask 82 is disposed on the focal plane P of the 1 st lens 71 so as to be spaced apart from the 1 st lens 71 by the focal length f1 of the 1 st lens 71. The high-order diffraction light mask 82 is disposed at a position overlapping the positions of the focal plane P where the high-order diffracted lights L21 and L22 are incident, but not overlapping the positions of the 0-order diffracted lights L01 and L02 and the 1-order diffracted lights L11 and L12. As a result, the high-order diffraction light mask 82 can block only the high-order diffracted lights L21 and L22 among the diffracted lights in the diffractive optical element 40.

In the illustrated example, the 0 th order photomask 81 and the higher order diffraction photomask 82 are plate-shaped members that absorb the 0 th order light L01 and L02 and the higher order diffraction light L21 and L22, respectively, but are not limited thereto. For example, the 0 th order photomask 81 and the higher order diffraction photomask 82 may direct the 0 th order light L01 and L02 and the higher order diffraction light L21 and L22, respectively, to the outside of the projection optical system 50.

Next, an operation of the illumination device 400 configured as described above will be described.

The light emitted from the light source 15 is first incident on the shaping optical system 30. In the shaping optical system 30, the light emitted from the light source 15 is amplified.

The light shaped by the shaping optical system 30 is then directed toward the diffractive optical element 40. In the 1 st element diffractive optical element 41, a part of the light emitted from the light source 15 is diffracted. The 2 nd element diffractive optical element 42 diffracts another part of the light emitted from the light source 15.

The light diffracted by the diffractive optical element 40 then travels toward the 1 st lens 71. The 0-order light beams L01 and L02 transmitted through the element diffractive optical elements 41 and 42 also travel toward the 1 st lens 71. In the 1 st lens 71, the 0 th order light L01, L02 is directed to a point a on the focal plane P of the 1 st lens 71. In addition, in the 1 st lens 71, the 1 st order diffracted light L11 and the higher order diffracted light L21 in the 1 st element diffractive optical element 41 are directed in parallel to the traveling direction of the 0 th order light L01. In addition, in the 1 st lens 71, the 1 st order diffracted light L12 and the higher order diffracted light L22 in the 2 nd element diffractive optical element 42 are directed in a direction parallel to the traveling direction of the 0 th order light L02.

Of the light passing through the 1 st lens 71, the 0-order light L01 and L02 enters the 0-order photomask 81. Further, the high-order diffracted lights L21 and L22 enter the high-order diffraction light mask 82. On the other hand, the 1 st order diffracted lights (1 st order diffracted light and 2 nd order diffracted light) L11 and L12 pass through the region between the 0 th order photomask 81 and the higher order diffracted light mask 82, and enter the 2 nd lens 72 while maintaining the traveling direction thereof.

The 1 st diffracted light L11 and the 2 nd diffracted light L12 incident on the 2 nd lens 72 converge toward a point on the 1 st reflecting surface 51 and a point on the 2 nd reflecting surface 52 of the projection optical system 50, respectively.

The 1 st diffracted light L11 incident on the 1 st reflecting surface 51 is reflected, and its traveling direction is changed at an angle exceeding 90 °. Then, the 1 st diffracted light L11 reflected by the 1 st reflecting surface 51 passes through the opening 61 provided in the cylindrical case 60 and enters the 1 st illuminated area Z1 on the projection surface S. The 2 nd diffracted light L12 incident on the 2 nd reflecting surface 52 is reflected, and its traveling direction is changed at an angle exceeding 90 °. At this time, the 2 nd diffracted light L12 reflected by the 2 nd reflecting surface 52 is directed in a direction different from the 1 st diffracted light L11 reflected by the 1 st reflecting surface 51. Then, the 2 nd diffracted light L12 reflected by the 2 nd reflecting surface 52 passes through the opening 61 provided in the cylindrical case 60 and enters the 2 nd illuminated area Z2 on the projection surface S, which is different from the 1 st illuminated area Z1.

According to embodiment 2 as described above, the lighting device 400 further includes: a 1 st lens 71 which is disposed between the diffractive optical element 40 and the projection optical system 50 along an optical path from the diffractive optical element 40 to the projection optical system 50, and which is disposed so as to be spaced apart from the diffractive optical element 40 by a focal length f1 of the 1 st lens 71; a 2 nd lens 72 disposed between the 1 st lens 71 and the projection optical system 50 along an optical path from the 1 st lens 71 to the projection optical system 50, and spaced apart from the 1 st lens 71 by a sum of a focal length f1 of the 1 st lens 71 and a focal length f2 of the 2 nd lens 72; and a 0-order photomask 81 disposed between the 1 st lens 71 and the 2 nd lens 72 along the optical path from the 1 st lens 71 to the 2 nd lens 72, and configured to intercept 0-order light L01, L02 in the diffractive optical element 40.

According to the illumination device 400, the 0 th-order light L01 and L02 transmitted through the diffractive optical element 40 can be prevented from being reflected or refracted by the projection optical system 50. This prevents the 0-order lights L01 and L02 from entering the eyes of the observer and causing a problem in safety, and prevents the 0-order light from entering the illuminated area and causing an abnormal area in which the brightness (luminance) rises sharply in comparison with the surrounding area in the illuminated area. Further, since the 1 st lens 71 is disposed at the distance from the diffractive optical element 40, the traveling paths of the 0 th order light L01, L02, 1 st order diffracted lights L11, L12, and higher order diffracted lights L21, L22 in the diffractive optical element 40 can be easily adjusted, and the 0 th order photomask 81 is disposed so as to block only the 0 th order lights L01, L02. Further, since the 2 nd lens 72 is disposed at the distance from the 1 st lens 71, the characteristics of the 1 st diffracted light L11 and the 2 nd diffracted light L12 passing through the 1 st lens 71 and the 2 nd lens 72 can be made to correspond to the characteristics of the 1 st diffracted light L11 and the 2 nd diffracted light L12 in the diffractive optical element 40. As a result, the illuminated regions Z1, Z2 can be illuminated in a desired pattern corresponding to the diffraction characteristics of the diffractive optical element 40 (e.g., interference fringe patterns recorded in the elemental diffractive optical elements 41, 42).

Further, according to embodiment 2 as described above, the lighting device 400 further includes: a 1 st lens 71 which is disposed between the diffractive optical element 40 and the projection optical system 50 along an optical path from the diffractive optical element 40 to the projection optical system 50, and which is disposed so as to be spaced apart from the diffractive optical element 40 by a focal length f1 of the 1 st lens 71; a 2 nd lens 72 disposed between the 1 st lens 71 and the projection optical system 50 along an optical path from the 1 st lens 71 to the projection optical system 50, and spaced apart from the 1 st lens 71 by a sum of a focal length f1 of the 1 st lens 71 and a focal length f2 of the 2 nd lens 72; and a higher-order diffraction light mask 82 disposed between the 1 st lens 71 and the 2 nd lens 72 along the optical path from the 1 st lens 71 to the 2 nd lens 72, for blocking higher-order diffraction light L21, L22 in the diffractive optical element 40.

According to the illumination device 400, the high-order diffracted lights L21, L22 in the diffractive optical element 40 can be prevented from being reflected or refracted by the projection optical system 50. This prevents the high-order diffracted lights L21 and L22 from entering the eyes of the observer and causing a problem in safety, and prevents the high-order diffracted lights L21 and L22 from being projected onto the projection plane S and illuminating the areas other than the illuminated areas Z1 and Z2, thereby making it difficult to recognize the illuminated areas Z1 and Z2. Further, since the 1 st lens 71 is disposed at the distance from the diffractive optical element 40, the traveling paths of the 0 th order light L01, L02, 1 st order diffracted lights L11, L12, and higher order diffracted lights L21, L22 in the diffractive optical element 40 can be easily adjusted, and the higher order diffraction light mask 82 is disposed so as to block only the higher order diffracted lights L21, L22. Further, since the 2 nd lens 72 is disposed at the distance from the 1 st lens 71, the characteristics of the 1 st diffracted light L11 and the 2 nd diffracted light L12 passing through the 1 st lens 71 and the 2 nd lens 72 can be made to correspond to the characteristics of the 1 st diffracted light L11 and the 2 nd diffracted light L12 in the diffractive optical element 40. As a result, the illuminated regions Z1, Z2 can be illuminated in a desired pattern corresponding to the diffraction characteristics of the diffractive optical element 40, for example, the interference fringe pattern recorded in the elemental diffractive optical element 4142).

While the embodiments and the modifications thereof have been described above, it is needless to say that a plurality of configurations described as different embodiments or different modifications may be appropriately combined.

Description of the reference symbols

Z1: 1 st illuminated area; z2: the 2 nd illuminated area; 10: an illumination device; 15: a light source; 32: a collimating lens; 40: a diffractive optical element; 41: a 1 st element diffractive optical element; 42: a 2 nd element diffractive optical element; 50: a projection optical system; 51: a 1 st reflecting surface; 52: a 2 nd reflecting surface; 71: a 1 st lens; 72: a 2 nd lens; 81: level 0 photomask 82: an advanced diffractive light mask.

Claims

1. An illumination device, having:

a light source that emits light;

the projection optical system directs one part of the 1 st order diffracted light diffracted by the diffractive optical element to a different direction from the other part of the 1 st order diffracted light.

2. The lighting device of claim 1,

the projection optical system directs 1 st-order diffracted light diffracted by the 1 st-element diffractive optical element and 2 nd-order diffracted light diffracted by the 2 nd-element diffractive optical element in different directions.

3. The lighting device according to claim 1 or 2,

the projection optical system is a reflecting element or a prism.

4. The lighting device according to claim 1 or 2,

the projection optical system includes: a half mirror that reflects a part of the 1 st order diffracted light diffracted by the diffractive optical element and transmits the other part; and a reflection element that reflects the other part of the 1 st order diffracted light transmitted through the half mirror.

5. The lighting device according to claim 1 or 2,

the projection optical system is a diffractive optical element for projection that diffracts the light diffracted by the diffractive optical element.

6. The lighting device of claim 5,

the diffractive optical element has: a 1 st element diffractive optical element that diffracts a part of the light emitted from the light source; and a 2 nd element diffractive optical element that diffracts another part of the light emitted from the light source,

7. The lighting device according to any one of claims 1 to 6,

the illumination device also has a collimating lens disposed between the light source and the diffractive optical element along an optical path from the light source to the diffractive optical element.

8. The lighting device according to any one of claims 1 to 7,

the projection optical system changes the traveling direction of a part of the 1 st order diffracted light diffracted by the diffractive optical element at an angle exceeding 90 DEG, and changes the traveling direction of another part of the 1 st order diffracted light diffracted by the diffractive optical element at an angle exceeding 90 deg.

9. The lighting device according to any one of claims 1 to 8,

the lighting device is housed in a cylindrical housing.

10. The lighting device of claim 9,

the housing is configured to be rotatable.

11. The lighting device according to any one of claims 1 to 10,

the lighting device is supported to be rotatable.

12. The lighting device according to any one of claims 1 to 11,

the projection optical system is supported to be rotatable.

13. The lighting device according to any one of claims 1 to 12,

the diffractive optical element is supported to be rotatable.

14. The lighting device according to any one of claims 1 to 13,

the lighting device further has:

15. The lighting device according to any one of claims 1 to 14,

the lighting device further has:

16. The lighting device of any one of claims 1 to 15,

the 1 st illuminated region and the 2 nd illuminated region extend along a straight line as a whole.