Illumination device

Abstract

To provide an illumination device capable of combining light beams with a simple configuration without using an additional member for beam combining, thereby creating a brighter image.SOLUTION: An illumination device 10 includes: a diffractive optical element 50 configured to receive laser light having a wavelength in a visible region and convert the laser light into a group of light rays corresponding to a group of dot patterns projected onto a projection surface S; and optical systems LD1 and LD2 configured to cause a first laser light Ray1LD1, which is parallel light having a wavelength in the visible region and converted into a first group of light rays Ray2LD1 corresponding to a first group of dot patterns, and a second laser light Ray1LD2, which is parallel light having a wavelength in the visible region and converted into a second group of light rays Ray2LD2 corresponding to a second group of dot patterns, to enter the diffractive optical element.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a lighting device. [Background technology]

[0002] There is known an illumination device (e.g., a projector) that uses multiple light sources that emit light of different wavelengths, such as RGB light sources, combines the light emitted by each light source using a dichroic mirror, then diffuses it using a homogenizer, and forms an image using a light modulation element such as LCOS (Liquid Crystal On Silicon) (see, for example, Non-Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Non-Patent Document 1] Optical Technology Information Magazine "Light Edge" No. 37 (Special Feature: Ushio's New Initiatives Part 2) [Retrieved February 19, 2024], Internet<URL:https: / / www.ushio.co.jp / jp / technology / lightedge / 201206 / 100438.html> Summary of the Invention [Problem to be solved by the invention]

[0004] However, the illumination device described in Non-Patent Document 1 requires an additional component (dichroic mirror) for combining the beams, which increases the number of components and increases costs.

[0005] The present disclosure has been made to solve such problems, and aims to provide an illumination device that can combine light beams with a simple configuration to create a brighter image without using any additional components for combining light beams. [Means for solving the problem]

[0006] The lighting device according to the present disclosure includes a diffractive optical element that receives laser light of a wavelength in the visible range and converts the laser light into a group of rays corresponding to a group of dot patterns to be projected onto a projection surface, and an optical system that causes first laser light of a wavelength in the visible range, which is parallel light that is converted into a first group of rays corresponding to a first group of dot patterns, and second laser light of a wavelength in the visible range, which is parallel light that is converted into a second group of rays corresponding to a second group of dot patterns, to be incident on the diffractive optical element.

[0007] With this configuration, it is possible to combine the beams with a simple configuration and create a brighter image without using any additional components for combining the beams.

[0008] In addition, in the above-mentioned lighting device, the first dot pattern group and the second dot pattern group may be formed on the projection surface shifted from each other by a predetermined distance in a predetermined direction by making the second laser light incident on the diffractive optical element at an incident angle different from the incident angle of the first laser light on the diffractive optical element.

[0009] In the above lighting device, the first dot pattern group may be a pattern in which dots are projected at a first dot pitch, and the predetermined distance may be 1 / 2 of the first dot pitch.

[0010] In the above illumination device, an incident angle of the second laser light with respect to the diffractive optical element may be half the diffraction angle of the first laser light.

[0011] In addition, in the above lighting device, the first dot pattern group and the second dot pattern group may be formed in an overlapping state by making the second laser light incident on the diffractive optical element at the same incident angle as the incident angle of the first laser light on the diffractive optical element.

[0012] In the lighting device, the first laser light and the second laser light may have the same wavelength.

[0013] In the above lighting device, the first laser light and the second laser light may have different wavelengths.

[0014] The above-described illumination device may further include a diffractive optical element onto which n (n is an integer of 2 or greater) laser beams are incident, the diffractive optical element converting the incident laser beams into a dot pattern group, the diffraction angles of the dot pattern groups being the same for each laser beam, and the angles of incidence of the n laser beams on the diffractive optical element being different from one another by 1 / n times the diffraction angles. [Effects of the Invention]

[0015] The present disclosure makes it possible to provide an illumination device that can combine light beams with a simple configuration to create a brighter image without using any additional components for combining light beams. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram illustrating the configuration of a lighting device 10. FIG. [Figure 2] 2 is a diagram (simplified diagram) of laser light sources LD (LD1 to LD4) as seen from the direction of arrow AR1 in FIG. [Figure 3] 3(a) is an enlarged view of the diffractive optical element 50 in FIG. 1 as seen from the direction of arrow AR1, and FIG. 3(b) is a cross-sectional view taken along line AA in FIG. 3(a). [Figure 4] 1 is an example of a group of dot patterns DP projected onto a projection surface S. [Figure 5] (a) Optical path diagram of laser light Ray1LD1 and Ray1LD2 at the CC cross section of Figure 2, (b) Optical path diagram of laser light Ray1LD3 and Ray1LD4 at the DD cross section of Figure 2, (c) Optical path diagram of laser light Ray1LD1 and Ray1LD3 at the EE cross section of Figure 2, (d) Optical path diagram of laser light Ray1LD2 and Ray1LD4 at the FF cross section of Figure 2. [Figure 6] 10(a) to 10(c) are examples of dot patterns DP projected onto a projection surface S. [Figure 7]2 is an enlarged view of an aperture 60 as seen in the direction of arrow AR1 in FIG. 1. [Figure 8] 1 is an example of an image formed by dot patterns DP (DPLD1 to DPLD4) formed on a projection surface S. FIG. [Figure 9] FIG. 1 is a schematic diagram illustrating the configuration of a lighting device 10 (modification). DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an illumination device 10 (image forming device) according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. Corresponding components in each drawing are designated by the same reference numerals, and redundant description will be omitted.

[0018] Fig. 1 is a schematic diagram of the configuration of the lighting device 10. Fig. 2 is a diagram (simplified diagram) of the laser light sources LD (LD1 to LD4) as seen from the direction of the arrow AR1 in Fig. 1.

[0019] As shown in FIGS. 1 and 2, the lighting device 10 includes a plurality of laser light sources LD (LD1 to LD4). The plurality of laser light sources LD are, for example, a plurality of laser light sources that emit laser light having the same wavelength in the visible range. The laser light Ray1 (Ray1) emitted by each of the plurality of laser light sources LD is LD1 ~Ray1 LD4 The laser light emitted by the laser light source LD1 is converted into parallel light by passing through a plurality of lenses 30 provided corresponding to the plurality of laser light sources LD, and then enters a diffractive optical element (DOE) 50. Hereinafter, the laser light emitted by the laser light source LD1 is referred to as laser light Ray1. LD1 Similarly, the laser light emitted from the laser light sources LD2 to LD4 is written as laser light Ray1. LD2 ~Ray1 LD4 Hereinafter, an example using four laser light sources LD1 to LD4 will be described, but the present invention is not limited to this. Two or more laser light sources, that is, a plurality of laser light sources, may be used.

[0020] Fig. 3(a) is an enlarged view of the diffractive optical element 50 in Fig. 1 as seen from the direction of arrow AR1, and Fig. 3(b) is a cross-sectional view taken along line AA in Fig. 3(a). The cross-sectional view taken along line BB in Fig. 3(a) is the same as the cross-sectional view taken along line AA.

[0021] The diffractive optical element 50 includes a microlens array, receives laser light Ray1 emitted from each laser light source LD and converted into parallel light by the lens 30, and converts (diffracts) the laser light Ray1 into a group of rays Ray2 corresponding to the dot pattern group to be projected onto the projection surface S. That is, the diffractive optical element 50 diffracts and splits the incident laser light Ray1 in the up, down, left, and right directions. The group of rays Ray2 becomes a bundle of parallel light beams with multiple directions. For example, the diffractive optical element 50 may be an "ardisia" product of SciVax. Alternatively, for example, the diffractive optical element 50 may be one described in Japanese Patent No. 7061823. However, the diffractive optical element 50 may have any configuration as long as it receives laser light (parallel light) and converts (diffracts) the laser light into a group of rays corresponding to the dot pattern group to be projected onto the projection surface S. For example, it may be a general diffraction grating with a groove structure. Hereinafter, the laser light Ray1 LD1 The transformed ray group corresponding to this is the ray group Ray2 LD1 Laser light Ray1 LD2 ~Ray1 LD4 Similarly, for the transformed ray group corresponding to LD2 ~Ray2 LD4 It is written as follows.

[0022] As shown in Figures 3(a) and 3(b), the microlens array of the diffractive optical element 50 includes a plurality of lenses 51 arranged two-dimensionally in the X and Y directions. Figures 3(a) and 3(b) show an example in which the lenses 51 are provided on the incident side of the diffractive optical element 50 (the incident side of the laser light Ray1), but this is not limiting. The lenses 51 may be provided on at least one of the incident side and the exit side of the diffractive optical element 50 (the incident side of the laser light Ray1 and the exit side of the laser light Ray1).

[0023] FIG. 4 shows an example of a dot pattern DP projected onto a projection surface S. Hereinafter, laser light Ray1 LD1 (Ray group Ray2 LD1 ) is the dot pattern DP LD1 Laser light Ray1 LD2 ~Ray1 LD4 (Ray group Ray2 LD2 ~Ray2 LD4 ) and the dot pattern DP LD2 ~DP LD4 It is written as follows.

[0024] The dot pattern is, for example, circular (see FIG. 4), but is not limited to this and may be rectangular or another shape.

[0025] If the pitch P of the lenses 51 (see FIG. 3(b)) becomes too small compared to the wavelength λ of the laser light emitted by the laser light source LD, diffraction will be difficult to occur. Therefore, as long as there are enough lenses 51 included within the distribution angle of the laser light to cause diffraction, the pitch P should be sufficiently larger than the wavelength λ of the laser light, for example, 5 times or more, and preferably 10 times or more.

[0026] The material of the diffractive optical element 50 is, for example, PDMS with a refractive index of 1.53.

[0027] Below, laser light Ray1 LD1 ~Ray1 LD4 (Ray group Ray2 1D2 ~Ray2 LD4 Hereinafter, it is assumed that the wavelength of the laser light emitted from each of the laser light sources LD1 to LD4 is 510 nm, the beam diameter of the laser light Ray1 (parallel light) incident on the diffractive optical element 50 is 5 mm, and the pitch P of the lenses 51 is 25.5 μm.

[0028] Figure 5(a) shows the laser beam Ray1 at the CC cross section in Figure 2. LD1 , Ray1 LD2The optical path diagram of the laser beam Ray1 in the DD cross section of Figure 2 is shown in Figure 5(b). LD3 , Ray1 LD4 The optical path diagram of the laser beam Ray1 in the EE cross section of Figure 2 is shown in Figure 5(c). LD1 , Ray1 LD3 Fig. 5(d) shows the optical path of the laser beam Ray1 at the FF cross section in Fig. 2. LD2 , Ray1 LD4 6(a) to 6(c) are examples of a dot pattern DP group projected onto a projection surface S. FIG.

[0029] Diffractive optical element 50 with laser light Ray 1 LD1 When the diffractive optical element 50 converts the incident light into a group of rays Ray2. LD1 As a result, the dot pattern DP shown in Figure 4 is projected onto the projection surface S. LD1 A group is formed (projected). The intervals L1 and L2 between the dots are, for example, approximately 20 mm at a position 1 m away from the diffractive optical element 50. Note that FIG. 4 (also FIGS. 6(a) to 6(c)) is an example (part) of a dot pattern, and in reality, a larger number of dot patterns than this are formed.

[0030] Laser light Ray 1 on diffractive optical element 50 LD1 The angle of incidence of the ray group Ray2 is 0 degrees on both the CC and EE cross sections (see Figures 5(a) and 5(c)). In this case, the diffraction angle θ1 is 1.1458 degrees. LD1 The 0th order light Ray2 that constitutes LD1_0 and 1st order light Ray2 LD1_1 The angle between the two.

[0031] Similarly, laser light Ray1 is incident on the diffractive optical element 50. LD2 is incident, the ray group Ray2 converted by the diffractive optical element 50 is LD2 As a result, the dot pattern DP shown in Figure 4 is projected onto the projection surface S. LD1 Dot pattern DP similar to the group LD2 A group is formed (projected).

[0032] However, as shown in FIG. 6(a), the dot pattern DPLD2 The group is a dot pattern DP LD1 A dot pattern DP LD1 The distance between the two points is 1 / 2 of the distance L2.

[0033] This is because the laser beam Ray1 is incident on the diffractive optical element 50. LD2 The incident angle and incident position of the laser beam Ray1 on the diffractive optical element 50 are LD1 This is because the incident angle and incident position are different from those of the light source.

[0034] That is, the laser beam Ray1 to the diffractive optical element 50 LD2 The incident angle of the laser beam Ray1 on the diffractive optical element 50 is angle θ2 on the CC cross section (see FIG. 5(a)), and is 0 degrees on the FF cross section (see FIG. 5(d)). The angle θ2 is half the diffraction angle θ1. When the diffraction angle θ1 is 1.1458 degrees, the angle θ2 is approximately 0.573 degrees. The laser light source LD2 emits laser beam Ray1 on the diffractive optical element 50. LD2 The incident angle of the light is θ2. LD2 is the reference axis (optical axis AX of laser light source LD1) LD1 ) is tilted at an angle θ2.

[0035] In addition, the laser beam Ray1 is incident on the diffractive optical element 50. LD2 The incident position of the laser beam Ray1 on the diffractive optical element 50 in the CC cross section is LD1 The incident position is shifted by a distance H1 from the incident position (see FIG. 5(a)). H1 is, for example, 40 mm.

[0036] As described above, the laser beam Ray1 impinges on the diffractive optical element 50. LD2 The incident angle and incident position of the laser beam Ray1 on the diffractive optical element 50 are LD1 As a result of the different incident angle and incident position, the dot pattern DP LD2 The group is a dot pattern DP LD1 A dot pattern DP LD1The angle θ2 and the distance H1 may be adjusted as needed.

[0037] Similarly, laser light Ray1 is incident on the diffractive optical element 50. LD3 is incident, the ray group Ray2 converted by the diffractive optical element 50 is LD3 As a result, the dot pattern DP shown in Figure 4 is projected onto the projection surface S. LD1 Dot pattern DP similar to the group LD3 A group is formed (projected).

[0038] However, as shown in FIG. 6(b), the dot pattern DP LD3 The group is a dot pattern DP LD1 A dot pattern DP in FIG. 6(b) is placed in a predetermined direction (to the right in FIG. 6(b)) at a predetermined distance from the group. LD1 The distance between the two points is 1 / 2 of the distance L1.

[0039] This is because the laser beam Ray1 is incident on the diffractive optical element 50. LD3 The incident angle and incident position of the laser beam Ray1 on the diffractive optical element 50 are LD1 This is because the incident angle and incident position are different from those of the light source.

[0040] That is, the laser beam Ray1 to the diffractive optical element 50 LD3 The incident angle of the ray group Ray2 is 0 degrees on the DD cross section (see Figure 5(b)) and is angle θ6 on the EE cross section (see Figure 5(c)). The angle θ6 is half the diffraction angle θ5. The diffraction angle θ5 is the angle of the ray group Ray2. LD1 The 0th order light Ray2 that constitutes LD1_0 and 1st order light Ray2 LD1_1 When the diffraction angle θ5 is 1.1458 degrees, the angle θ6 is approximately 0.573 degrees. The laser light source LD3 irradiates the laser beam Ray1 onto the diffractive optical element 50. LD3 The incident angle of the light is θ6. LD3 is the reference axis (optical axis AX of laser light source LD1) LD1 ) is tilted at an angle θ6.

[0041] In addition, the laser beam Ray1 is incident on the diffractive optical element 50. LD3 The incident position of the laser beam Ray1 on the diffractive optical element 50 in the EE cross section is LD1 The incident position is shifted by a distance H3 from the incident position (see FIG. 5(c)). H3 is, for example, 40 mm.

[0042] As described above, the laser beam Ray1 impinges on the diffractive optical element 50. LD3 The incident angle and incident position of the laser beam Ray1 on the diffractive optical element 50 are LD1 As a result of the different incident angle and incident position, the dot pattern DP LD3 The group is a dot pattern DP LD1 A dot pattern DP in FIG. 6(b) is placed in a predetermined direction (to the right in FIG. 6(b)) at a predetermined distance from the group. LD1 The angle θ6 and the distance H3 may be adjusted as needed.

[0043] Similarly, laser light Ray1 is incident on the diffractive optical element 50. LD4 is incident, the ray group Ray2 converted by the diffractive optical element 50 is LD4 As a result, the dot pattern DP shown in Figure 4 is projected onto the projection surface S. LD1 Dot pattern DP similar to the group LD4 A group is formed (projected).

[0044] However, as shown in FIG. 6(c), the dot pattern DP LD4 The group is a dot pattern DP LD1 A dot pattern DP in FIG. 6(c) is placed in a predetermined direction (rightward and downward in FIG. 6(c)) at a predetermined distance from the group. LD1 The distance between the two points is L1 and L2 (1 / 2).

[0045] This is because the laser beam Ray1 is incident on the diffractive optical element 50. LD4 The incident angle and incident position of the laser beam Ray1 on the diffractive optical element 50 are LD1 This is because the incident angle and incident position are different from those of the light source.

[0046] That is, the laser beam Ray1 to the diffractive optical element 50 LD4 The angle of incidence of the ray group Ray2 is angle θ4 on the DD cross section (see Figure 5(b)) and angle θ8 on the FF cross section (see Figure 5(d)). The angle θ4 is half the diffraction angle θ3. The diffraction angle θ3 is the angle of incidence of the ray group Ray2. LD3 The 0th order light Ray2 that constitutes LD3_0 and 1st order light Ray2 LD3_1 (See Figure 5(b)). When the diffraction angle θ3 is 1.1458 degrees, the angle θ4 is approximately 0.573 degrees. On the other hand, the angle θ8 is half the diffraction angle θ7. The diffraction angle θ7 is the angle between the group of rays Ray2 and Ray3. LD2 The 0th order light Ray2 that constitutes LD2_0 and 1st order light Ray2 LD2_1 When the diffraction angle θ7 is 1.1458 degrees, the angle θ8 is approximately 0.573 degrees. The laser light source LD4 emits laser light Ray1 to the diffractive optical element 50. LD4 The incident angles of the beams are θ4 and θ8. LD4 is the reference axis (optical axis AX of laser light source LD1) LD1 ) are arranged at angles θ4 and θ8.

[0047] In addition, the laser beam Ray1 is incident on the diffractive optical element 50. LD4 The incident position of the laser beam Ray1 on the diffractive optical element 50 in the DD cross section is LD1 The laser beam Ray1 is shifted by a distance H2 from the incident position of the diffractive optical element 50 (see FIG. 5(b)). H2 is, for example, 40 mm. LD4 The incident position of the laser beam Ray1 on the diffractive optical element 50 in the FF cross section is LD1 The incident position is shifted by a distance H4 from the incident position (see FIG. 5(d)). H4 is, for example, 40 mm.

[0048] As described above, the laser beam Ray1 impinges on the diffractive optical element 50. LD4 The incident angle and incident position of the laser beam Ray1 on the diffractive optical element 50 are LD1As a result of the different incident angle and incident position, the dot pattern DP LD4 The group is a dot pattern DP LD1 A dot pattern DP in FIG. 6(c) is placed in a predetermined direction (rightward and downward in FIG. 6(c)) at a predetermined distance from the group. LD1 The angles θ4 and θ8 and the distances H2 and H4 may be adjusted as appropriate.

[0049] As described above, the laser beam Ray1 (Ray1 LD1 ~Ray1 LD4 ) can be incident on the laser light sources LD1 to LD4, thereby forming a high density, high brightness dot pattern group with half the pitch (here, approximately 10 mm) (see FIG. 6(c)). That is, by simply arranging the laser light sources LD1 to LD4 as described above, it is possible to obtain four times the luminous flux (four times the brightness) without using any additional members. Furthermore, by arranging additional laser light sources between the laser light sources, it is possible to obtain eight times the luminous flux (eight times the brightness). In this embodiment, the laser light sources LD (LD1 to LD4) arranged as described above are an example of the optical system of the present disclosure.

[0050] The group of rays Ray2 (Ray2 LD1 ~Ray2 LD4 ) enters the aperture 60. Instead of the aperture 60, a transmissive liquid crystal element may be used.

[0051] The aperture 60 is an optical filter that is disposed on the optical path of the group of rays Ray2 converted by the diffractive optical element 50 and includes an opaque region that does not transmit the group of rays Ray2 and a transmissive region that transmits visible light. The aperture 60 (opaque region) may be, for example, a dichroic filter.

[0052] Figure 7 is an enlarged view of aperture 60 as seen from the direction of arrow AR1 in Figure 1. In Figure 7, the arrowed area A1 in aperture 60 represents an opaque area through which a group of rays Ray2 of a specific color (here, blue-green with a wavelength of 510 nm) does not pass. This opaque area is a filter area that reflects or absorbs the group of rays Ray2 of the specific color. Meanwhile, the hatched area HT1 in aperture 60 represents a transmissive area through which all visible light passes.

[0053] In the lighting device 10 configured as described above, when the laser light sources LD (LD1 to LD4) are turned on, an image formed on the projection surface S will be described.

[0054] When the laser light source LD (LD1 to LD4) is turned on, the laser light Ray1 (Ray1) emitted by the laser light source LD (LD1 to LD4) LD1 ~Ray1 LD4 The laser beam Ray1 (Ray1) is converted into parallel light by passing through the lens 30, and then enters the diffractive optical element 50 (see FIGS. 5(a) to 5(d)). The diffractive optical element 50 converts the laser beam Ray1 (Ray1) converted into parallel light by passing through the lens 30 into the diffractive optical element 50 (see FIGS. 5(a) to 5(d)). LD1 ~Ray1 LD4 ) and the laser light Ray1 (Ray1 LD1 ~Ray1 LD4 ) is projected onto the projection surface S, the corresponding dot pattern group Ray2 (Ray2 LD1 ~Ray2 LD4 )

[0055] The group of rays Ray2 (Ray2 LD1 ~Ray2 LD4 ) does not pass through the arrow area A1 (opaque area) of the aperture 60. On the other hand, the group of rays Ray2 (Ray2 LD1 ~Ray2 LD4 ) passes through the hatched area HT1 (transparent area) of the aperture 60. As a result, a plurality of dot patterns DP (DP LD1 ~DP LD4) is formed (projected) in a specific color (here, green with a wavelength of 510 nm). LD1 ~DP LD4 ) is an example of an image formed by the aperture 60. Note that a similar image is formed when a transmission type liquid crystal element is used instead of the aperture 60.

[0056] As described above, according to this embodiment, it is possible to create a brighter image by combining beams with a simple configuration without using any additional component for combining beams.

[0057] In addition, in the above embodiment, four laser light sources are used to project a dot pattern with four times the brightness, but the number of light sources can be increased or decreased depending on the desired projection brightness and dot density.

[0058] For example, in the above embodiment, the laser light sources are arranged in two rows and two columns in the X and Y directions, but this can be changed to a total of nine laser light sources arranged in three rows and three columns.

[0059] In the case of a 2-row, 2-column arrangement, the angle of incidence on the diffractive optical element was shifted by 1 / 2 of the diffraction angle, but in the case of a 3-row, 3-column arrangement, the angle of incidence is shifted by 1 / 3 of the diffraction angle, so that the dot pattern groups corresponding to each laser light are projected with a shift of 1 / 3 of the distance between the dot patterns.

[0060] Next, a modified example will be described.

[0061] FIG. 9 is a schematic diagram of the illumination device 10 (modification).

[0062] As shown in FIG. 9, a reflecting surface 70 may be disposed between the laser light sources LD (LD1 to LD4) and the diffractive optical element 50, which are arranged to face each other. A plurality of reflecting surfaces 70 are disposed corresponding to the plurality of laser light sources. In this modification, the laser light sources LD (LD1 to LD4) and the reflecting surfaces 70 arranged as described above are an example of the optical system of the present disclosure. Note that, as long as the laser light Ray1 can be incident on the diffractive optical element 50 as described above, any optical system may be used, not limited to the optical system of the above embodiment or the optical system of this modification.

[0063] This modification also provides the same effects as the above embodiment.

[0064] In the above embodiment, an example has been described in which a plurality of laser light sources LD (LD1 to LD4) that emit laser light of the same wavelength in the visible range are used as the plurality of laser light sources, but this is not limiting. For example, a plurality of laser light sources that emit laser light of different wavelengths in the visible range may be used as the plurality of laser light sources. In this way, when a plurality of laser light sources that emit laser light of different wavelengths in the visible range are used, an expensive multiplexing prism such as a dichroic mirror is not required.

[0065] In the above embodiment, the plurality of dot patterns DP (DP LD1 ~DP LD4 ) groups are formed on the projection surface S in a state where they are shifted from each other by a predetermined distance in a predetermined direction (see FIGS. 6(a) to 6(c)), but this is not limiting. For example, a plurality of dot patterns DP (DP LD1 ~DP LD4 ) may be formed in a state where they overlap each other on the projection surface S. This can be realized, for example, by adjusting the angles of incidence θ2, θ4, θ6, θ8 (the angles of the optical axes of the laser light sources LD1 to LD4 with respect to the reference axis) with respect to the diffractive optical element 50 and the distances H1, H2, H3, H4 between the laser beams. For example, the angles of incidence θ2, θ4, θ6, θ8 of the laser beam Ray1 with respect to the diffractive optical element 50 may be adjusted by adjusting the angles of incidence θ2, θ4, θ6, θ8 of the laser beam Ray1 with respect to the diffractive optical element 50. LD1 This can be achieved by making the incident angle the same as that of the incident light (for example, 0 degrees).

[0066] All numerical values ​​shown in the above embodiments are merely examples, and it goes without saying that other appropriate numerical values ​​can be used. The above embodiments are merely examples in all respects. The present disclosure should not be interpreted as being limited by the description of the above embodiments. The present disclosure can be implemented in various other forms without departing from its spirit or main features. [Explanation of symbols]

[0067] 10...Lighting equipment 30...lens 50...Diffractive optical element 51...Lens 60...Aperture 70…Reflective surface A1...Arrow area AX LD1 -AX LD4 …optical axis DP(DP LD1 -DP LD4 )…Dot pattern HT1...Hatched area LD (LD1-LD4)...Laser light source Ray1(Ray1 LD1 -Ray1 LD4 )...Laser light Ray2(Ray2 LD1 -Ray2 LD4 )...ray group Ray2LD1_0, Ray2LD2_0, Ray2LD3_0…0th order light Ray2LD1_1, Ray2LD2_1, Ray2LD3_1…1st light S…Projection surface θ1, θ3, θ5, θ7...diffraction angles θ2, θ4, θ6, θ8…Incidence angle

Claims

1. a diffractive optical element that receives laser light having a wavelength in the visible range and converts the laser light into a group of light rays corresponding to a group of dot patterns to be projected onto a projection surface; an optical system that causes a first laser beam having a wavelength in the visible range, which is parallel light that is converted into a first group of rays corresponding to a first dot pattern group, and a second laser beam having a wavelength in the visible range, which is parallel light that is converted into a second group of rays corresponding to a second dot pattern group, to be incident on the diffractive optical element.

2. 2. The lighting device of claim 1, wherein the first dot pattern group and the second dot pattern group are formed on the projection surface offset from each other by a predetermined distance in a predetermined direction by making the second laser light incident on the diffractive optical element at an incident angle different from the incident angle of the first laser light on the diffractive optical element.

3. the first dot pattern group is a pattern in which dots are projected at a first dot pitch, The lighting device according to claim 2 , wherein the predetermined distance is half the first dot pitch.

4. 4. The illumination device according to claim 3, wherein an incident angle of the second laser light with respect to the diffractive optical element is half the diffraction angle of the first laser light.

5. 2. The lighting device according to claim 1, wherein the first dot pattern group and the second dot pattern group are formed in an overlapping state by making the second laser light incident on the diffractive optical element at the same incident angle as the incident angle of the first laser light on the diffractive optical element.

6. The illumination device according to claim 1 , wherein the first laser light and the second laser light have the same wavelength.

7. The lighting device according to claim 1 , wherein the first laser light and the second laser light have different wavelengths.

8. an illumination device comprising: a diffractive optical element onto which n (n is an integer of 2 or greater) laser beams are incident; the diffractive optical element converts the incident laser beams into a dot pattern group, the diffraction angles of the dot pattern groups are the same for each laser beam; and the angles of incidence of the n laser beams with respect to the diffractive optical element differ from one another by 1 / n times the diffraction angles.

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