Projection device

Abstract

To provide a projector capable of projecting a linear pattern that has a thin line width and has excellent quality.SOLUTION: A projector includes: a light source for emitting parallel light; a diffraction optical element disposed on a side in which the parallel light in the light source is emitted; and a lens that is disposed on a side opposite to the light source in the diffraction optical element and has curvature in a predetermined direction. The lens projects a linear pattern extending along a vertical direction to a projection surface by generating multiple bright spots lined up in the direction vertical to the predetermined direction, wherein lengths of the bright spots along the vertical direction are equal to or more than an interval along the vertical direction between the adjacent bright spots in the multiple bright spots, and lengths of the bright spots along the predetermined direction are shorter than the lengths of the bright spots along the vertical direction in all of the multiple bright spots.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a projection apparatus. [Background technology]

[0002] Diffractive optical elements are known that use the diffraction phenomenon of light to spatially branch light. Diffractive optical elements are small and lightweight, yet can achieve the same functions as refractive optical elements such as lenses and prisms, and are used in a variety of fields such as lighting and optical measurement.

[0003] In addition, a projection device has been disclosed that uses a diffractive optical element in which basic units are arranged periodically in two dimensions and diffracts incident light in two dimensions, thereby projecting a linear pattern onto a projection surface (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 158419 Summary of the Invention [Problem to be solved by the invention]

[0005] In the projection device described in Patent Document 1, the smaller the diameter of the light incident on the diffractive optical element, the thinner the line pattern that can be obtained. Here, the line width of the linear pattern refers to the width of the linear pattern in a direction perpendicular to the direction in which the linear pattern extends.

[0006] However, in the projection device described in Patent Document 1, the distance between multiple bright spots generated on the projection surface by the diffracted light from the diffractive optical element and the positional shift of the bright spots due to distortion become larger as the diameter of the light incident on the diffractive optical element becomes smaller. Therefore, if the diameter of the light incident on the diffractive optical element is reduced to narrow the line width of the linear pattern, the distance between the bright spots becomes larger, causing parts of the linear pattern to split, or the positional shift of the bright spots causes parts of the linear pattern to wave, which may degrade the quality of the linear pattern.

[0007] An object of one aspect of the present disclosure is to provide a projection device capable of projecting a linear pattern with a narrow line width and good quality. [Means for solving the problem]

[0008] A projection device according to one aspect of the present disclosure comprises a light source that emits parallel light, a diffractive optical element arranged on the side of the light source from which the parallel light is emitted, and a lens arranged on the opposite side of the diffractive optical element from the light source and having a curvature in a predetermined direction, wherein the lens generates a plurality of bright spots arranged in a direction perpendicular to the predetermined direction on the projection surface, thereby projecting a linear pattern extending along the perpendicular direction onto the projection surface, wherein the length of the bright spots along the perpendicular direction is greater than or equal to the distance along the perpendicular direction between adjacent bright spots among the plurality of bright spots, and wherein the length of the bright spots along the predetermined direction for all of the plurality of bright spots is shorter than the length of the bright spots along the perpendicular direction. Effect of the Invention

[0009] According to one aspect of the present disclosure, it is possible to provide a projection device capable of projecting a linear pattern with a narrow line width and good quality. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of an overall configuration of a projection device according to an embodiment. [Diagram 2] 2 is a plan view illustrating the configuration of a diffractive optical element included in the projection device of FIG. 1. [Diagram 3] 3 is a plan view of a concave-convex pattern of a basic unit in the diffractive optical element of FIG. 2. [Figure 4] 3 is a cross-sectional view taken along line AA in FIG. 2. [Diagram 5] 2A to 2C are schematic views illustrating linear patterns according to the embodiment; [Figure 6] FIG. 6 is an enlarged view of a region B in FIG. [Figure 7] 11 is a diagram illustrating an evaluation area of ​​a linear pattern on a projection surface. FIG. [Figure 8] FIG. 8 is an enlarged view of a region C in FIG. [Figure 9] 9A and 9B are diagrams illustrating the four corner areas in FIG. 8. [Figure 10] FIG. 1 is a table showing the specifications and evaluation results of Examples 1 to 5. [Figure 11] 11 is a diagram illustrating a simulation result of a linear pattern according to Example 1. FIG. [Figure 12] 13 is a diagram illustrating a simulation result of a linear pattern according to Example 2. FIG. [Figure 13] 13 is a diagram illustrating a simulation result of a linear pattern according to Example 3. FIG. [Figure 14] 13 is a diagram illustrating a simulation result of a linear pattern according to Example 4. FIG. [Figure 15] 13 is a diagram illustrating a simulation result of a linear pattern according to Example 5. FIG. [Figure 16] FIG. 13 is a table showing the specifications and evaluation results of Examples 6 to 8. [Figure 17] FIG. 13 is a table showing the specifications and evaluation results of Examples 9 to 11. [Figure 18] 13 is a diagram illustrating a simulation result of a linear pattern according to Example 6. FIG. [Figure 19] FIG. 13 is a diagram illustrating a simulation result of a linear pattern according to Example 7. [Figure 20] FIG. 13 is a diagram illustrating a simulation result of a linear pattern according to Example 8. [Figure 21]FIG. 13 is a diagram illustrating a simulation result of a linear pattern according to Example 9. [Figure 22] FIG. 13 is a diagram illustrating a simulation result of a linear pattern according to Example 10. [Diagram 23] FIG. 13 is a diagram illustrating a simulation result of a linear pattern according to Example 11. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. However, the embodiments shown below are merely examples of projection devices for realizing the technical ideas of the present embodiment, and are not limited to the following. Note that the sizes and positional relationships of the members shown in each drawing may be exaggerated to clarify the explanation. In each drawing, the same components are given the same reference numerals, and duplicate explanations will be omitted as appropriate.

[0012] In the figures shown below, directions may be indicated by the x-axis, y-axis, and z-axis, with the y-direction along the y-axis indicating a specific direction in the projection plane. The x-direction along the x-axis indicates a direction perpendicular to the y-direction in the projection plane. The z-direction along the z-axis indicates a direction perpendicular to the projection plane. The planar view in the terms of the embodiments refers to viewing the diffractive optical element provided in the projection device according to the embodiment from the z-direction. However, these do not limit the orientation of the projection device when in use, and the orientation of the projection device is arbitrary.

[0013] <Embodiment> (Example of overall configuration of projection device 1) 1 is a diagram showing an example of the overall configuration of a projection device 1 according to this embodiment. The projection device 1 includes a light source 10, a diffractive optical element 20, and a lens 30.

[0014] The light source 10 emits parallel light toward the diffractive optical element 20. In this embodiment, the light source 10 is a semiconductor laser, and emits a laser beam that is a substantially parallel bundle of light rays. "Substantially parallel" does not require strict parallelism, but means that a deviation from parallelism that is generally recognized as an error is permitted.

[0015] The cross-sectional shape of the laser beam emitted by the light source 10 in a plane perpendicular to the central axis is, for example, approximately circular. Approximately circular does not require a strict perfect circle, but means that a deviation from a perfect circle that is generally considered to be an error is permitted. In this case, the "difference that is generally considered to be an error" is, for example, a difference of 1 / 10 or less of the laser beam diameter.

[0016] The wavelength of the light emitted by the light source 10 is not particularly limited, but for example, a wavelength in the visible light region from about 380 nm to about 780 nm or a wavelength in the near infrared region from about 800 nm to about 1200 nm can be used. The light source 10 is not limited to a semiconductor laser, and an LED (Light Emitting Diode) or the like may be used.

[0017] The diffractive optical element 20 is an optical element disposed on the side from which the parallel light of the light source 10 is emitted. The diffractive optical element 20 diffracts the parallel laser beam incident from the light source 10 in two-dimensional directions so as to generate a plurality of bright spots arranged in a two-dimensional array on the projection surface S, and emits a plurality of parallel laser beams toward the lens 30.

[0018] The lens 30 is disposed on the opposite side of the diffractive optical element 20 from the light source 10, and is a lens having a curvature in a predetermined direction. In this embodiment, the lens 30 is a cylindrical lens having a curvature in the y direction and no curvature in the x direction. The lens 30 has refractive power (lens power) only in the y direction. The y direction corresponds to the predetermined direction, and the x direction corresponds to a direction perpendicular to the predetermined direction.

[0019] The lens 30 may be a plano-convex, biconvex or meniscus cylindrical lens. The lens 30 may also be configured to have a curvature in the y direction by combining a plurality of optical elements such as lenses and prisms.

[0020] The lens 30 receives the parallel laser beam emitted from the diffractive optical element 20 and emits focused light. From the viewpoint of suppressing aberration, the lens 30 is preferably disposed so that the surface with the greater curvature faces the light source 10 side.

[0021] The lens 30 projects a plurality of bright spots formed by converging the plurality of laser beams diffracted by the diffractive optical element 20 in the y direction onto the projection surface S. In other words, the lens 30 can project a linear pattern extending along the x direction onto the projection surface S by generating a plurality of bright spots aligned in the x direction on the projection surface S.

[0022] Figure 1 shows an example of three linear patterns L aligned along the y direction, but there is no particular limit to the number of linear patterns L aligned along the y direction, and the number may be one, or any number greater than or equal to two.

[0023] The projection surface S is typically a screen, but is not limited to this and may be, for example, the wall surface of a building, or a virtual plane in space.

[0024] (Configuration example of diffractive optical element 20) The configuration of the diffractive optical element 20 will be described with reference to Fig. 2 to Fig. 4. Fig. 2 is a plan view illustrating an example of the configuration of the diffractive optical element 20. Fig. 3 is a plan view illustrating an example of a concavo-convex pattern of a basic unit 21 in the diffractive optical element 20. Fig. 4 is a cross-sectional view taken along line AA in Fig. 2.

[0025] As shown in FIG. 2, the diffractive optical element 20 includes a plurality of basic units 21 that are periodically arranged two-dimensionally along each of the x and y directions. The plurality of basic units 21 are arranged at a pitch Px in the x direction and at a pitch Py in the y direction. Here, the pitch refers to the distance between the centers of adjacent basic units 21. In FIG. 2, adjacent basic units 21 are arranged without a gap between them, so that the pitch Px coincides with the length of the basic unit 21 in the x direction, and the pitch Py coincides with the length of the basic unit 21 in the y direction. In this embodiment, the diameter of the laser beam emitted by the light source 10 is larger than the pitch Px. Note that, when the specification value of the line width LW is LT, the diameter R of the laser beam satisfies the following formulas (1) and (2) regardless of the number of lines Ln. R ≥ √(Px 2 +Py 2 ) ··· (1) R ≧ (4 × λ × f) / (π × LT) (2)

[0026] As shown in Fig. 3, the basic unit 21 has a periodic structure of a concave-convex pattern as a binary phase distribution. Each of the basic units 21 has the same periodic structure of a concave-convex pattern. In Fig. 3, the black filled areas indicate convex portions, and the white areas indicate concave portions. The concave-convex pattern of the basic unit 21 diffracts the parallel light incident from the light source 10 in two-dimensional directions.

[0027] 4, the diffractive optical element 20 includes a light-transmitting member 22 made of glass or the like, and convex portions 23 formed on the surface of the light-transmitting member 22. In the diffractive optical element 20, regions on the surface of the light-transmitting member 22 where the convex portions 23 are not formed become concave portions 24. The convex portions 23 and the concave portions 24 form a concave-convex pattern layer 25 on the light-transmitting member 22. The convex portions 23 can be formed including a material such as glass or resin.

[0028] As long as the light-transmitting member 22 is transmissive to incident light, various materials such as glass and resin can be used. Using an optically isotropic material such as glass or quartz is more preferable from the viewpoint of improving the quality of the linear pattern L projected by the projection device 1, since these materials do not have birefringence. For example, forming an anti-reflection film or the like made of a multilayer film on the interface with the air of the light-transmitting member 22 is preferable because it can reduce light reflection by the light-transmitting member 22.

[0029] 4 illustrates a configuration in which an uneven pattern is formed on one side of the light-transmitting member 22, but the diffractive optical element 20 may have an uneven pattern formed on both sides of the light-transmitting member 22. The phase distribution in the basic unit 21 of the diffractive optical element 20 is not limited to that based on an uneven pattern as long as it can impart a phase difference to the incident light, and may have a refractive index that changes two-dimensionally.

[0030] The number of basic units 21 in the diffractive optical element 20 does not need to be an integer, and for example, the boundary between an area such as the periphery that does not have an uneven pattern and an area that has an uneven pattern does not necessarily need to coincide with the boundary of the basic units 21.

[0031] 2 and 3 show an example in which the flat surface of the diffractive optical element 20 and the projection surface S are substantially parallel to each other, but they do not necessarily have to be substantially parallel to each other and may be tilted.

[0032] (An example of linear pattern L) Fig. 5 is a schematic diagram illustrating a linear pattern L. Fig. 6 is an enlarged view of a region B in Fig. 5.

[0033] 5, the diffraction divergence angles θx and θy represent the divergence angles of all the laser beams diffracted by the diffractive optical element 20. The diffraction divergence angle θx is the divergence angle in the x direction, and the diffraction divergence angle θy is the divergence angle in the y direction.

[0034] The lens distance ZL represents the distance between the surface of the diffractive optical element 20 facing the light source 10 and the principal point (optical center) of the lens 30. The projection distance ZS represents the distance between the surface of the diffractive optical element 20 facing the light source 10 and the projection plane S.

[0035] 6, the linear pattern L is composed of multiple bright spots Ls arranged in the x direction. The bright spots Ls are generated by each of the multiple laser beams diffracted by the diffractive optical element 20. The cross-sectional shape of the bright spots Ls in a plane perpendicular to the central axis of the laser beam becomes a substantially elliptical shape with the y direction as the minor axis by being focused in the y direction by the lens 30.

[0036] In FIG. 6, bright spot length Qx represents the length of each of the multiple bright spots Ls along the x direction. Bright spot length Qy represents the length of each of the multiple bright spots Ls along the y direction. Bright spot length Qx corresponds to the major axis length of the ellipse that constitutes the bright spot Ls, and bright spot length Qy corresponds to the minor axis length of the ellipse. Bright spot intervals Vx and Vy represent the distance between the centers of adjacent bright spots in the multiple bright spots Ls. Bright spot interval Vx represents the bright spot interval in the x direction, and bright spot interval Vy represents the bright spot interval in the y direction.

[0037] In this embodiment, the bright spot length Qx is longer than the bright spot interval Vx, and all of the multiple bright spots Ls have a bright spot length Qy shorter than the bright spot length Qx. The projection device 1 generates multiple bright spots Ls on the projection surface S so that the bright spots Ls are aligned along the x direction, thereby projecting a linear pattern L extending along the x direction onto the projection surface S. For all of the multiple bright spots Ls, the bright spot length Qy and the bright spot length Qx satisfy the relationship of the following formula (3). Qy≦Qx×{π×(LT 2 )} / (4 × λ × f) · · · (3)

[0038] The distortion ε refers to the distance between the center of the bright spot Ls located lowest in the y direction (negative y-axis side) and the center of the bright spot Ls located highest in the y direction (positive y-axis side) among the multiple bright spots Ls included in one linear pattern L. The positive y-axis side refers to the direction in which the arrow indicating the y-axis points, and the negative y-axis side refers to the direction opposite to the direction in which the arrow indicating the y-axis points.

[0039] Here, when the central axis of the diffractive optical element 20 and the central axis of the projection surface S are approximately aligned, the bright spots Ls generated on the projection surface S may have a greater positional deviation as they are generated closer to the four corners of the projection surface S. This positional deviation occurs due to distortion of diffracted light by the diffractive optical element 20. Fig. 6 shows bright spots Ls that are displaced due to pincushion distortion among the multiple bright spots Ls. The distortion ε is a value indicating the amount of positional deviation due to such distortion.

[0040] The line width LW represents the width along the y direction of the linear pattern L. In this embodiment, the line width LW is defined as the sum of the bright spot length Qy and the distortion ε.

[0041] Examples and Comparative Examples Examples and Comparative Examples will be described below, but the present invention is not limited to these Examples. Example 1 is an Example, Examples 2 to 5 are Comparative Examples, and Examples 6 to 11 are Examples.

[0042] (Evaluation method) Table 1 shows the main specifications of the projection devices in the examples and comparative examples. In Table 1, the wavelength λ represents the wavelength of the parallel light emitted by the light source 10, and the number of lines Ln represents the number of linear patterns L projected onto the projection surface S.

[0043] [Table 1]

[0044] In the examples and comparative examples, a diffractive optical element 20 satisfying the specification values ​​shown in Table 1 was designed by simulation, and the linear pattern L projected using the designed diffractive optical element 20 was determined by simulation and evaluated.

[0045] In the design of the diffractive optical element 20 and the simulation for evaluating the linear pattern, an iterative Fourier transform algorithm (IFTA) that repeats a Fourier transform and an inverse Fourier transform, and a ray tracing method were used.

[0046] (Evaluation area of ​​linear pattern L on projection surface S) Fig. 7 is a diagram for explaining an evaluation region of a linear pattern L on a projection surface S in an embodiment and a comparative example. Fig. 8 is an enlarged view of a region C in Fig. 7. Fig. 9 is a diagram showing the four corner regions in Fig. 8.

[0047] In the evaluation of the linear pattern L, as shown in Fig. 7, the projection surface S was represented by x and y coordinates, and ten linear patterns L approximately parallel to each other were projected onto the projection surface S. The length of the projection surface S was 600.0 mm in the x direction and 440.0 mm in the y direction. The area C is an area corresponding to the first quadrant on the projection surface S.

[0048] 8, five of the ten linear patterns, namely linear pattern L1 to linear pattern L5, were included in region C. The size of region C was 300.0 mm in the x direction and 220.0 mm in the y direction.

[0049] As shown in FIG. 9, in the example and comparative example, areas D1, D2, D3 and D4 at the four corners of area C were used as evaluation areas, and linear patterns L1 and L5 included in the evaluation areas were evaluated.

[0050] (Evaluation Results) Fig. 10 is a diagram showing a list of specifications and evaluation results of Examples 1 to 5. Figs. 11 to 15 are diagrams showing simulation results of the linear pattern L.

[0051] In the diagram showing the configuration of each example in Fig. 10, only the main components are shown for convenience in order to show the differences between the examples. The bright spot interval Vx, the bright spot interval Vy, the distortion ε, and the line width LW vary within one linear pattern L, but Fig. 10 shows the maximum values ​​for each. This also applies to Figs. 16 and 17 shown below.

[0052] 11 to 15, region D1 indicates the region where the x coordinate is 0.0 mm to 40.0 mm, region D2 indicates the region where the x coordinate is 260.0 mm to 300.0 mm, region D3 indicates the region where the x coordinate is 0.0 mm to 40.0 mm, and region D4 indicates the region where the x coordinate is 260.0 mm to 300.0 mm.

[0053] <Example 1> As shown in Figure 10, the projection device 1 of Example 1 is configured to include a diffractive optical element 20 and a lens 30 having a curvature only in the y direction, similar to that shown in Figure 1, and the incident beam diameter φ is 7200.0 μm.

[0054] In Example 1, the configuration of the concave-convex pattern layer 25 in the diffractive optical element 20, the pitches Px and Py, the lens distance ZL, the focal length f, etc. were optimized, and as a result, the distortion ε was 63.0 μm or less, and the line width LW was 98.0 μm or less. The bright spot length Qy was 1 / 205 of the bright spot length Qx. Note that, at a lens distance ZL such that all of the diffracted light by the diffractive optical element 20 is incident on the lens 30, ZL=ZS-f always holds.

[0055] 11, in each of the regions D1 to D4, splitting and distortion were suppressed, and a linear pattern L of good quality was obtained. Here, splitting of the linear pattern L means that the linear pattern L is divided into a plurality of independent parts.

[0056] <Example 2> 10, the projection device 1X2 according to Example 2 includes a diffractive optical element 20X2 and does not include a lens, and the incident beam diameter φ is 100.0 μm. The distortion ε is 4053.0 μm or less, and the line width LW is 4153.0 μm or less. The bright spot length Qy is equal to the bright spot length Qx.

[0057] As shown in Fig. 12, the linear pattern L in each region was split into multiple point-like bright spots Ls. The bright spot lengths Qx and Qy were 100.0 μm, but as in region D2, the positional deviation of the bright spots Ls due to the strain ε became large, and as a result, the line width LW became thicker than in Example 1.

[0058] <Example 3> As shown in Fig. 10, the projection device 1X3 according to Example 3 includes a diffractive optical element 20X3 and does not include a lens, and the incident beam diameter φ is 800.0 μm. The distortion ε is 546.0 μm or less, and the line width LW is 1346.0 μm or less. The bright spot length Qy is equal to the bright spot length Qx.

[0059] As shown in Fig. 13, in the linear pattern L of each region, no splitting was observed, but the wavy positional deviation became large. In addition, in response to the increase in the incident beam diameter φ, the linear pattern L became thicker overall compared to Example 1.

[0060] <Example 4> As shown in Fig. 10, the projection device 1X4 according to Example 4 includes a diffractive optical element 20X4 and a lens 30X4 having a curvature only in the x direction, and the incident beam diameter φ is 100.0 μm. The distortion ε is 3762.0 μm or less, and the line width LW is 3862.0 μm or less. The bright spot length Qy is 1 / 100 of the bright spot length Qx.

[0061] 14, large positional deviation and division occurred in the linear pattern L in region D2. Although the individual linear patterns L themselves became thinner, the line width LW became thicker compared to Example 1 as a result of the large positional deviation.

[0062] <Example 5> As shown in Fig. 10, the projection device 1X5 according to Example 5 includes a lens 30X5 having a curvature only in the x direction and a diffractive optical element 20X5 arranged on the projection surface S side of the lens 30X5, and the incident beam diameter φ is set to 100.0 μm. The distortion ε is 3882.0 μm or less, and the line width LW is 3982.0 μm or less. The bright spot length Qy is 1 / 102 of the bright spot length Qx.

[0063] As shown in Fig. 15, large positional deviation and division occurred in the linear pattern L in region D2. Although the individual linear patterns L themselves became thinner, the positional deviation of the bright spots Ls became larger, resulting in a thicker line width LW compared to Example 1.

[0064] From the above results, it was found that among Examples 1 to 5, the configuration of the projection device 1 according to Example 1 is more suitable for projecting a linear pattern L having a narrow line width LW and good quality.

[0065] Next, a description will be given of Examples 6 to 11. In Examples 6 to 11, similar to the projection device 1 according to Example 1, a diffractive optical element 20 and a lens 30 having a curvature only in the y direction are provided, and the values ​​of each parameter are changed from those in Example 1.

[0066] Fig. 16 is a diagram showing the specifications and evaluation results of Examples 6 to 8. Fig. 17 is a diagram showing the specifications and evaluation results of Examples 9 to 11. Figs. 18 to 23 are diagrams illustrating simulation results of linear patterns. Fig. 18 shows the results of Example 6, Fig. 19 shows the results of Example 7, Fig. 20 shows the results of Example 8, Fig. 21 shows the results of Example 9, Fig. 22 shows the results of Example 10, and Fig. 23 shows the results of Example 11, respectively.

[0067] 18 to 23, region D1 indicates the region where the x coordinate is from 0.0 mm to 40.0 mm, and region D3 indicates the region where the x coordinate is from 0.0 mm to 40.0 mm.

[0068] 18, 19 and 22, region D2 indicates the region where the x coordinate is from 260.0 mm to 300.0 mm, and region D4 indicates the region where the x coordinate is from 260.0 mm to 300.0 mm.

[0069] In FIG. 20, area D2 indicates an area where the x coordinate is from 300.0 mm to 340.0 mm, and area D4 indicates an area where the x coordinate is from 300.0 mm to 340.0 mm.

[0070] In FIG. 21, area D2 indicates an area where the x coordinate is from 110.0 mm to 150.0 mm, and area D4 indicates an area where the x coordinate is from 110.0 mm to 150.0 mm.

[0071] In FIG. 23, region D2 indicates linear pattern L5 in the region where the x coordinate is from 130.0 mm to 170.0 mm, and region D4 indicates linear pattern L1 in the region where the x coordinate is from 130.0 mm to 170.0 mm.

[0072] <Example 6> 16, in Example 6, the number of lines Ln was changed to 20 in comparison with Example 1. In Example 6, the distortion ε and line width LW did not change compared with Example 1, as shown in FIGS.

[0073] <Example 7> As shown in FIG. 16, in Example 7, the pitches Px and Py of the basic units in the diffractive optical element 20 were changed from those in Example 1. In Example 7, the line width LW was changed to be about twice that of Example 1, and as a result, the incident beam diameter was changed and the pitches Px and Py were also changed. The distortion ε was 127.0 μm and the line width LW was 198.0 μm, which were thicker than those in Example 1. The bright spot length Qy was 1 / 51 of the bright spot length Qx. As shown in FIG. 19, no splitting or distortion was observed in the linear pattern L in each evaluation area, and a linear pattern L of good quality was obtained.

[0074] <Example 8> As shown in FIG. 16, in Example 8, the incident beam diameter φ was changed to 8000.0 μm, and the pitches Px and Py of the basic units in the diffractive optical element 20 and the diffraction divergence angles θx and θy were changed. In Example 8, the diffraction divergence angles θx and θy were changed from those in Example 1, resulting in a change in the incident beam diameter and a change in the pitches Px and Py. The distortion ε was 68.0 μm, and the line width LW was 100.0 μm, which were almost the same as those in Example 1. The bright spot length Qy was 1 / 250 of the bright spot length Qx. As shown in FIG. 20, no splitting or distortion was observed in each evaluation area, and a linear pattern L of good quality was obtained.

[0075] <Example 9> As shown in FIG. 16, in Example 9, the incident beam diameter φ was changed to 3600.0 μm, and the pitches Px and Py of the basic units in the diffractive optical element 20 and the focal length f of the lens 30 were changed compared to Example 1. In Example 9, the projection distance ZS was changed from Example 1, resulting in a change in the focal length f, and the incident beam diameter and pitches Px and Py were also changed. The distortion ε was 63.0 μm, and the line width LW was 98.0 μm, which were almost the same as those in Example 1. As shown in FIG. 21, in each evaluation region, although some intensity fluctuation was observed in the linear pattern L, no splitting or distortion was observed, and a linear pattern L of good quality was obtained. The bright spot length Qy was 1 / 103 of the bright spot length Qx.

[0076] <Example 10> As shown in FIG. 16, in Example 10, the wavelength λ was changed to 850.0 nm, the incident beam diameter φ was changed to 15200.0 μm, and the pitches Px and Py of the basic units in the diffractive optical element 20 were changed, compared to Example 1. In Example 10, the wavelength λ was changed from Example 1, resulting in a change in the incident beam diameter, and the pitches Px and Py were also changed. The distortion ε was 64.0 μm, and the line width LW was 99.0 μm, which were almost the same as those in Example 1. The bright spot length Qy was 1 / 434 of the bright spot length Qx. As shown in FIG. 22, no splitting or distortion was observed in each evaluation area, and a linear pattern L of good quality was obtained.

[0077] <Example 11> As shown in FIG. 16, in Example 11, the wavelength λ was changed to 850.0 nm, the incident beam diameter φ was changed to 4200.0 μm, and the pitches Px and Py of the basic units in the diffractive optical element 20 and the diffraction divergence angles θx and θy were changed, respectively, compared to Example 1. In Example 11, all the parts changed in Examples 6 to 10 above were changed from Example 1, and as a result, the focal length f was changed, and the incident beam diameter and pitches Px and Py were also changed. The distortion ε was 132.0 μm, and the line width LW was 195.0 μm, which was thicker than Example 1. The bright spot length Qy was 1 / 67 of the bright spot length Qx. As shown in FIG. 23, no splitting or distortion was observed in each evaluation area, and a linear pattern L of good quality was obtained.

[0078] 16 to 23, it was found that linear patterns L having a narrow line width LW and good quality could be projected in Examples 6 to 11. From the viewpoint of narrowing the line width LW, it was found that the line width LW is preferably 250.0 μm or less, and more preferably 100.0 μm or less.

[0079] In addition, the thinner the line width LW is, the smaller the spot length Qy must be. When the specification value of the line width LW is LT, the incident beam diameter R must satisfy the following two equations. R ≧ (4 × λ × f) / (π × LT) (4) R ≥ √(Px 2 + Py 2 ) ··· (5) As a result, the pitches Px and Py can be increased as the line width LW becomes narrower, so the bright spot interval and distortion can be reduced. Since the ratio of the bright spot interval and distortion to the line width LW is almost constant even if the line width changes, it can be considered that the ratio is almost constant regardless of the line width LW from the viewpoint of improving the quality of the line width LW.

[0080] Here, when the minimum line width LW that can be realized by the diffractive optical element 20 alone was examined, it was found that the following points affect the line width LW. · Wavelength λ: The longer the wavelength, the larger the linewidth LW. Projection distance ZS: The longer it is, the larger the line width LW will be. Diffraction spread angle θx: The wider the angle, the larger the line width LW. · Diffraction divergence angle θy: The wider the angle, the larger the line width LW. The length of the linear pattern L in the x direction: the shorter it is, the easier it is to make the line width LW smaller. When projecting a single linear pattern L, the line width LW is smallest. In consideration of these, the line width LW was calculated using realistic specifications that make it easy to reduce the line width LW, and it was found that the line width LW is preferably 250.0 μm or less.

[0081] <Function and effect of the projection device 1> As described above, the projection device 1 includes the light source 10 that emits parallel light, the diffractive optical element 20 that is disposed on the side of the light source 10 from which the parallel light is emitted, and the lens 30 that is disposed on the opposite side of the diffractive optical element 20 from the light source 10 and has a curvature in the y direction (predetermined direction). The lens 30 projects a linear pattern L extending along the x direction onto the projection surface S by generating a plurality of bright spots Ls arranged in the x direction (direction perpendicular to the predetermined direction) on the projection surface S. The bright spot length Qx (the length of the bright spots along the x direction) is equal to or longer than the bright spot interval Vx (the interval between adjacent bright spots in the plurality of bright spots along the x direction), and all of the plurality of bright spots Ls have a bright spot length Qy (the length of the bright spots along the y direction) that is shorter than the bright spot length Qx. In all of the plurality of bright spots Ls, the bright spot length Qy and the bright spot length Qx satisfy the relationship of the above formula (3).

[0082] By making the bright spot length Qx longer than the bright spot interval Vx, splitting and distortion can be suppressed, and a linear pattern L of good quality can be projected. Furthermore, by making the bright spot length Qy shorter than the bright spot length Qx, the line width LW of the linear pattern L extending along the x direction can be narrowed. As a result, a projection device 1 can be provided that can project a linear pattern L of good quality with a narrow line width LW.

[0083] In the projection device described in Patent Document 1, the distance between multiple bright spots generated on the projection surface by the diffracted light from the diffractive optical element and the positional deviation of the bright spots due to distortion become larger as the diameter of the light incident on the diffractive optical element becomes smaller. The smaller the pitches Px and Py are, the larger the distance between the bright spots and the distortion become. The pitches Px and Py must satisfy the following formula when the diameter of the incident light is R. R ≥ √(Px 2 +Py 2 )

[0084] In addition, in the case of a single diffractive optical element, the diameter of the incident light must be equal to the diameter of the bright spot. Therefore, to narrow the line width with a single diffractive optical element, the diameter of the incident light must be reduced. As a result, the smaller the diameter of the incident light, the greater the positional deviation, which is due to the small pitch.

[0085] From the viewpoint of narrowing the line width LW of the linear pattern L, the bright spots Ls preferably have a bright spot length Qy of 1 / 50 or less of the bright spot length Qx. The bright spot length Qy is more preferably 250.0 μm or less, and even more preferably 100.0 μm or less.

[0086] In this embodiment, the lens 30 projects a plurality of linear patterns L onto the projection surface S, and the plurality of linear patterns L are parallel to one another. For example, when the projection device 1 is applied to a sensing purpose or the like and projects the linear pattern L from the projection device 1 as a probe light, the probe light can be irradiated over a wider range with high spatial resolution.

[0087] In this embodiment, the cross-sectional shape of the laser beam (parallel light) in a plane perpendicular to the central axis thereof is substantially circular. This makes it possible to suppress the anisotropy of the diffraction by the diffractive optical element 20.

[0088] In this embodiment, the diffractive optical element 20 includes a plurality of basic units 21. Each of the basic units 21 has the same concave-convex pattern layer 25, and is arranged at a predetermined pitch Px at least along the x direction, and the incident beam diameter φ is larger than the pitch Px. If the specification value of the line width LW is LT, the diameter of the laser beam satisfies the above formulas (1) and (2) regardless of the number of lines Ln. With this configuration, one laser beam incident on the diffractive optical element 20 can be efficiently diffracted in the x direction by using one entire basic unit 21.

[0089] In this embodiment, the diffractive optical element 20 emits a substantially parallel laser beam (parallel light), and the lens 30 receives the substantially parallel laser beam emitted from the diffractive optical element 20. In other words, the lens 30 is an object-side telecentric lens. With this configuration, the distance between the diffractive optical element 20 and the lens 30 does not affect the linear pattern L on the projection surface S, so that the degree of freedom in component arrangement, etc. in the projection device 1 can be improved.

[0090] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0091] The projection device according to the embodiment can be applied to various fields that use optical techniques, such as light-based sensing, such as LiDAR (Light Detection And Ranging), and image projection devices, such as projectors. [Explanation of symbols]

[0092] 1 Projection device 10 light source 20 Diffractive optical element 21 Basic Unit 22 Translucent material 23 Convex 24 Recess 25 Concave and convex pattern layer 30 Lenses L Linear Pattern S projection surface Px, Py pitch θx, θy Diffraction spread angle ZL Lens Distance ZS projection distance Ls bright spot LW Line width Vx, Vy bright spot spacing Qx, Qy Bright spot length ε Strain D1, D2, D3, D4 area f focal length φ Incident beam diameter

Claims

1. A light source that emits parallel light; a diffractive optical element disposed on a side of the light source from which the parallel light is emitted; a lens disposed on the opposite side of the diffractive optical element from the light source and having a curvature in a predetermined direction; the lens generates a plurality of bright points aligned in a direction perpendicular to the predetermined direction on a projection surface, thereby projecting a linear pattern extending along the perpendicular direction onto the projection surface; a length of the bright spot along the vertical direction is equal to or greater than a distance between adjacent bright spots in the plurality of bright spots along the vertical direction, A projection device in which all of the plurality of bright spots have a length of the bright spot along the predetermined direction that is shorter than the length of the bright spot along the perpendicular direction.

2. 2. The projection device according to claim 1, wherein the length of each of the plurality of bright spots along the predetermined direction is 1 / 50 or less of the length of each of the bright spots along the perpendicular direction.

3. 3. The projection device according to claim 1, wherein the length of the bright spot along the predetermined direction is 250 [mu]m or less.

4. 4. The projection device according to claim 1, wherein the length of the bright spot along the predetermined direction is 100 [mu]m or less.

5. The lens projects the plurality of linear patterns onto the projection surface, The projection device according to claim 1 , wherein the linear patterns are parallel to each other.

6. 6. The projection device according to claim 1, wherein a cross-sectional shape of the collimated light in a plane perpendicular to a central axis of the collimated light is substantially circular.

7. The diffractive optical element includes a plurality of basic units, The plurality of basic units each have the same concave-convex pattern layer and are formed side by side at least at a predetermined pitch along the perpendicular direction, The projection device according to claim 6 , wherein a diameter of the approximately circular cross-sectional shape of the parallel light is larger than the pitch.

8. The diffractive optical element emits parallel light, The projection device according to claim 1 , wherein the lens receives the parallel light emitted from the diffractive optical element.

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