CN115808837A - Projection device - Google Patents

Abstract

The invention provides a projection device capable of projecting a linear pattern with a fine line width and good quality. The projection device includes: a light source emitting parallel light; a diffractive optical element disposed on a side of the light source from which the parallel light is emitted; and a lens that is disposed on a side of the diffractive optical element opposite to the light source and has a curvature in a predetermined direction, the lens generating a plurality of bright points arranged in a direction perpendicular to the predetermined direction on a projection surface, thereby projecting a linear pattern extending in the perpendicular direction onto the projection surface, a length of the bright points in the perpendicular direction being equal to or longer than a distance between adjacent ones of the plurality of bright points in the perpendicular direction, and a length of the bright points in the predetermined direction of all of the plurality of bright points being shorter than a length of the bright points in the perpendicular direction.

Description

Projection device

Technical Field

The present disclosure relates to a projection device.

Background

A diffractive optical element is known which spatially branches light by utilizing a diffraction phenomenon of light. Although small and lightweight, diffractive optical elements can achieve the same function as refractive optical elements such as lenses and prisms, and are used in various fields such as illumination and optical measurement.

Further, there is disclosed a projection apparatus that projects a line pattern onto a projection surface using a diffractive optical element in which basic cells are periodically arranged in a two-dimensional direction and incident light is diffracted in the two-dimensional direction (for example, see patent document 1).

Documents of the prior art

Patent document

Patent document 1: international publication No. 2020/158419

Disclosure of Invention

Problems to be solved by the invention

In the projection apparatus described in patent document 1, a line pattern having a narrower line width can be obtained as the diameter of light incident on the diffractive optical element is reduced. Here, the line width of the line pattern refers to the width of the line pattern in the direction perpendicular to the direction in which the line pattern extends.

However, in the projection apparatus described in patent document 1, the smaller the diameter of the incident light to the diffractive optical element, the larger the distance between the plurality of bright points generated on the projection surface by the diffracted light generated by the diffractive optical element and the larger the positional deviation of the bright points due to distortion. Therefore, when the diameter of incident light to the diffractive optical element is reduced in order to reduce the line width of the linear pattern, the distance between the bright points increases, and a part of the linear pattern is split, or a part of the linear pattern fluctuates due to positional deviation of the bright points, and the quality of the linear pattern may be degraded.

An object of one embodiment of the present disclosure is to provide a projection apparatus capable of projecting a linear pattern having a small line width and good quality.

Means for solving the problems

A projection apparatus according to an embodiment of the present disclosure includes: a light source emitting parallel light; a diffractive optical element disposed on a side of the light source from which the parallel light is emitted; and a lens that is disposed on a side of the diffractive optical element opposite to the light source and has a curvature in a predetermined direction, the lens generating a plurality of bright points arranged in a direction perpendicular to the predetermined direction on a projection surface, thereby projecting a linear pattern extending in the perpendicular direction onto the projection surface, a length of the bright points in the perpendicular direction being equal to or longer than a distance between adjacent ones of the plurality of bright points in the perpendicular direction, and a length of the bright points in the predetermined direction of all of the plurality of bright points being shorter than a length of the bright points in the perpendicular direction.

Effects of the invention

According to one embodiment of the present disclosure, a projection apparatus capable of projecting a linear pattern having a small line width and high quality can be provided.

Drawings

Fig. 1 is a diagram illustrating an overall configuration of a projection apparatus according to an embodiment.

Fig. 2 is a plan view illustrating a structure of a diffractive optical element provided in the projection apparatus of fig. 1.

Fig. 3 is a plan view of the concave-convex pattern of the basic unit in the diffractive optical element of fig. 2.

Fig. 4 isbase:Sub>A sectional viewbase:Sub>A-base:Sub>A of fig. 2.

Fig. 5 is a schematic view illustrating a line pattern according to an embodiment.

Fig. 6 is an enlarged view of the region B in fig. 5.

Fig. 7 is a diagram illustrating an evaluation area of a line pattern on a projection plane.

Fig. 8 is an enlarged view of the region C in fig. 7.

Fig. 9 is a diagram showing four corner regions in fig. 8.

Fig. 10 is a graph showing the specification and evaluation results of examples 1 to 5.

Fig. 11 is a diagram illustrating a simulation result of a line pattern based on example 1.

Fig. 12 is a diagram illustrating a simulation result of a line pattern based on example 2.

Fig. 13 is a diagram illustrating a simulation result of a line pattern based on example 3.

Fig. 14 is a diagram illustrating a simulation result of the line pattern based on example 4.

Fig. 15 is a diagram illustrating a simulation result of a line pattern based on example 5.

FIG. 16 is a graph showing the specifications and evaluation results of examples 6 to 8.

FIG. 17 is a graph showing the specifications and evaluation results of examples 9 to 11.

Fig. 18 is a diagram illustrating a simulation result of a line pattern based on example 6.

Fig. 19 is a diagram illustrating a simulation result of a line pattern based on example 7.

Fig. 20 is a diagram illustrating a simulation result of a line pattern based on example 8.

Fig. 21 is a diagram illustrating a simulation result of a line pattern based on example 9.

Fig. 22 is a diagram illustrating a simulation result of the line pattern based on example 10.

Fig. 23 is a diagram illustrating a simulation result of a line pattern based on example 11.

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. However, the embodiment described below is an example of a projection apparatus for embodying the technical idea of the present embodiment, and is not limited to the embodiment described below. In addition, the sizes, positional relationships, and the like of the members shown in the drawings may be exaggerated for clarity of description. In the drawings, the same components are denoted by the same reference numerals, and overlapping description is appropriately omitted.

In the drawings shown below, directions are sometimes indicated by x-axis, y-axis, and z-axis, and a y-direction along the y-axis indicates a predetermined direction in the projection plane. The x-direction along the x-axis represents a direction perpendicular to the y-direction within the projection plane. The z direction along the z axis represents a direction orthogonal to the projection plane. The term "planar view" in the terms of the embodiments refers to a view of the diffractive optical element provided in the projection apparatus according to the embodiments as viewed from the z direction. However, these are not intended to limit the orientation of the projection device during use, and the orientation of the projection device may be arbitrary.

Description of the preferred embodiments

(example of the entire configuration of the projection apparatus 1)

Fig. 1 is a diagram showing an example of the overall configuration of a projection apparatus 1 according to the present embodiment. The projection device 1 includes a light source 10, a diffractive optical element 20, and a lens 30.

The light source 10 emits parallel light toward the diffractive optical element 20. In the present embodiment, the light source 10 is a semiconductor laser and emits a laser beam as a bundle of substantially parallel light rays. By substantially parallel, it is meant that the difference from parallel, which is generally considered to be the degree of error, is not required to be strictly parallel.

The cross-sectional shape of the laser beam in a plane orthogonal to the central axis of the laser beam emitted from the light source 10 is, for example, substantially circular. The substantially circular shape is not a perfect circle, but means a circle that allows a difference from a perfect circle, which is generally regarded as an error. In this case, "difference which is generally considered to be the degree of error" is, for example, a difference of 1/10 or less of the laser beam diameter.

The wavelength of the light emitted from the light source 10 is not particularly limited, and for example, a wavelength in a visible light region of about 380nm to about 780nm and a wavelength in a near infrared region of about 800nm to about 1200nm 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.

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

The lens 30 is a lens that is disposed on the opposite side of the diffractive optical element 20 from the light source 10 and has a curvature in a predetermined direction. In the present embodiment, the lens 30 is a cylindrical lens having 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 a predetermined direction, and the x direction corresponds to a direction perpendicular to the predetermined direction.

The lens 30 may be any one of a cylindrical lens of plano-convex, bi-convex, and meniscus. Further, the lens 30 having curvature in the y direction may be configured by combining a plurality of optical elements such as lenses and prisms.

The lens 30 receives the parallel laser beam emitted from the diffractive optical element 20 and emits a converging light. From the viewpoint of suppressing aberrations, the lens 30 is preferably disposed so that the surface having a large curvature faces the light source 10.

The lens 30 projects a plurality of bright points, which are obtained by condensing 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 in the x direction onto the projection surface S by generating a plurality of bright points aligned in the x direction on the projection surface S.

In fig. 1, three linear patterns L arranged along the y direction are illustrated, but the number of linear patterns L arranged in the y direction is not particularly limited, and may be one or may be any number of two or more.

The projection surface S is typically a screen, but is not limited thereto, and may be, for example, a wall surface of a building or a virtual plane in space.

(example of the configuration of the diffractive optical element 20)

Referring to fig. 2 to 4, the structure of the diffractive optical element 20 is explained. Fig. 2 is a plan view illustrating the structure of the diffractive optical element 20. Fig. 3 is a plan view illustrating the concave-convex pattern of the basic cell 21 in the diffractive optical element 20. Fig. 4 isbase:Sub>A sectional viewbase:Sub>A-base:Sub>A of fig. 2.

As shown in fig. 2, the diffractive optical element 20 includes a plurality of basic cells 21 periodically arranged in a two-dimensional manner along the x direction and the y direction, respectively. The plurality of basic cells 21 are arranged at a pitch Px in the x direction and at a pitch Py in the y direction. Here, the pitch means a distance between centers of adjacent basic cells 21. In fig. 2, since adjacent base cells 21 are arranged without a gap, the pitch Px corresponds to the length of the base cell 21 in the x direction, and the pitch Py corresponds to the length of the base cell 21 in the y direction. In the present embodiment, the diameter of the laser beam emitted from the light source 10 is larger than the pitch Px. When the specification value of the line width LW is LT, the diameter R of the laser beam satisfies the following expressions (1) and (2) regardless of the number Ln of lines.

R≥√(Px ² +Py ² )…(1)

R≥(4×λ×f)/(π×LT)…(2)

As shown in fig. 3, the basic cell 21 has a periodic configuration of a concave-convex pattern as a binary phase distribution. Each of the plurality of basic cells 21 has the same periodic structure of the uneven pattern. In fig. 3, the black areas indicate convex portions, and the blank areas indicate concave portions. The concave-convex pattern provided in the basic cell 21 diffracts parallel light incident from the light source 10 in a two-dimensional direction.

As shown in fig. 4, the diffractive optical element 20 includes a light-transmissive member 22 made of glass or the like, and a convex portion 23 formed on a surface of the light-transmissive member 22. In the diffractive optical element 20, the areas where the convex portions 23 are not formed on the surface of the translucent member 22 serve as the concave portions 24. The convex portions 23 and the concave portions 24 constitute a concave-convex pattern layer 25 on the light-transmissive member 22. The convex portion 23 may be formed of a material such as glass or resin.

As long as the light-transmitting member 22 has light-transmitting properties with respect to incident light, various materials such as resin can be used in addition to glass. If optically isotropic materials such as glass and quartz are used, they do not have birefringence, and therefore, it is more preferable from the viewpoint of improving the quality of the line pattern L projected by the projection apparatus 1. It is preferable to form an antireflection film or the like composed of a multilayer film on the interface between the light-transmissive member 22 and the air, for example, because light reflection by the light-transmissive member 22 can be reduced.

In fig. 4, the configuration in which the concave-convex pattern is formed on one surface of the light-transmissive member 22 is illustrated, but the diffractive optical element 20 may be formed with the concave-convex pattern on both surfaces of the light-transmissive member 22. The phase distribution in the basic cell 21 of the diffractive optical element 20 is not limited to the phase distribution based on the concave-convex pattern, and may be a phase distribution in which the refractive index changes two-dimensionally, as long as the phase difference can be given to the incident light.

The number of the basic cells 21 in the diffractive optical element 20 is not necessarily an integer, and for example, the boundary between the region such as the peripheral portion not having the concave-convex pattern and the region having the concave-convex pattern may not necessarily coincide with the boundary of the basic cell 21.

In fig. 2 and 3, the planar portion of the diffractive optical element 20 is illustrated as being substantially parallel to the projection surface S, but the planar portion and the projection surface S are not necessarily substantially parallel to each other and may be inclined.

(example of line pattern L)

Fig. 5 is a schematic view illustrating the line pattern L. Fig. 6 is an enlarged view of the region B in fig. 5.

In fig. 5, the diffraction divergence angles θ x and θ y represent the divergence angles of the entire plurality of laser beams diffracted by the diffractive optical element 20. The diffraction divergence angle θ x is a divergence angle in the x direction, and the diffraction divergence angle θ y is a divergence angle in the y direction.

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

As shown in fig. 6, the linear pattern L is formed by a plurality of bright spots Ls arranged in the x direction. The bright spot Ls is generated by each of the plurality of laser beams diffracted by the diffractive optical element 20. The cross-sectional shape of the bright spot Ls in a plane orthogonal to the central axis of the laser beam is converged in the y direction by the lens 30, and becomes a substantially elliptical shape having the y direction as the minor axis.

In fig. 6, the bright point length Qx indicates the length of each of the plurality of bright points Ls along the x direction. The bright point length Qy indicates the length of each of the plurality of bright points Ls along the y direction. The bright point length Qx corresponds to the major axis length of the ellipse constituting the bright point Ls, and the bright point length Qy corresponds to the minor axis length of the ellipse. The bright point intervals Vx and Vy indicate distances between centers of adjacent bright points among the plurality of bright points Ls. The bright point interval Vx represents the bright point interval in the x direction, and the bright point interval Vy represents the bright point interval in the y direction.

In the present embodiment, the light spot length Qx is longer than the light spot interval Vx, and the light spot length Qy of all of the plurality of light spots Ls is shorter than the light spot length Qx. The projection apparatus 1 generates a plurality of bright spots Ls on the projection surface S such that the bright spots Ls are arranged in the x direction, thereby projecting the linear pattern L extending in the x direction onto the projection surface S. In all of the plurality of bright points Ls, the bright point length Qy and the bright point length Qx satisfy the relationship of the following expression (3).

Qy≤Qx×{π×(LT ² )}/(4×λ×f)…(3)

The distortion ∈ indicates a distance between the center of a bright spot Ls located at the lowest position (y-axis negative side) in the y direction and the center of a bright spot Ls located at the highest position (y-axis positive side) in the y direction, among a plurality of bright spots Ls included in one linear pattern L. The positive side of the y-axis indicates a direction in which an arrow indicating the y-axis is directed, and the negative side of the y-axis indicates a direction opposite to the direction in which the arrow indicating the y-axis is directed.

Here, in a state where the central axis of the diffractive optical element 20 substantially coincides with the central axis of the projection surface S, there are cases where the positional deviation is larger in some of the plurality of bright spots Ls generated on the projection surface S as the bright spots are generated at positions closer to the four corners of the projection surface S. The positional shift is generated due to distortion of diffracted light generated by the diffractive optical element 20. Fig. 6 shows a bright spot Ls, which is shifted in position due to pincushion distortion, among the plurality of bright spots Ls. The distortion epsilon is a value representing the amount of positional shift caused by such distortion.

The line width LW represents the width of the line pattern L in the y direction. In the present embodiment, the sum of the bright point length Qy and the distortion ∈ is the line width LW.

Examples and comparative examples

The following examples and comparative examples are described, but the present invention is not limited to these examples at all. In addition, example 1 is an example, examples 2 to 5 are comparative examples, and examples 6 to 11 are examples.

(evaluation method)

Table 1 shows the main specification values of the projection apparatuses in the examples and comparative examples. In table 1, the wavelength λ represents the wavelength of the parallel light emitted from the light source 10, and the number Ln of lines represents the number of linear patterns L projected on the projection surface S.

[ TABLE 1 ]

Item	Specification value
		Wavelength lambda	405.0nm
Number of lines Ln	10 root of Chinese angelica
		Projection distance ZS	500.0mm
Diffraction divergence angle thetax	60.0deg
		Diffraction divergence angle θ y	45.0deg

In the examples and comparative examples, the diffractive optical elements 20 satisfying the specification values shown in table 1 were designed by simulation, and the line pattern L projected by using the designed diffractive optical elements 20 was obtained and evaluated by simulation.

In the design of the diffractive optical element 20 and the simulation of the evaluation of the line pattern, an Iterative Fourier Transform (IFTA) method and a ray tracing method are used, in which a Fourier Transform and an inverse Fourier Transform are repeated.

(evaluation region of line pattern L on projection surface S)

Fig. 7 is a diagram illustrating the evaluation area of the linear pattern L on the projection surface S in the examples and comparative examples. Fig. 8 is an enlarged view of the region C in fig. 7. Fig. 9 is a diagram showing four corner regions in fig. 8.

In the evaluation of the linear pattern L, as shown in fig. 7, the projection surface S is represented by x and y coordinates, and 10 linear patterns L substantially parallel to each other are projected on the projection surface S. The length of the projection surface S is 600.0mm in the x-direction and 440.0mm in the y-direction. The region C corresponds to the first quadrant of the projection plane S.

As shown in fig. 8, the region C includes five of the line patterns L1 to L5 out of 10 line patterns. The size of the area C is 300.0mm in the x-direction and 220.0mm in the y-direction.

As shown in fig. 9, in the example and the comparative example, the regions D1, D2, D3, and D4 at the four corners of the region C were set as evaluation regions, and the linear patterns L1 and L5 included in the evaluation regions were evaluated.

(evaluation results)

Fig. 10 is a table showing a list of specifications and evaluation results of examples 1 to 5. Fig. 11 to 15 are diagrams showing simulation results of the line pattern L.

In the diagram of fig. 10 showing the configuration of each example, only main components are shown for convenience to show the difference between the examples. The bright point interval Vx, the bright point interval Vy, the distortion ∈ and the line width LW vary within one line pattern L, but the respective maximum values are shown in fig. 10. This is the same in fig. 16 and 17 shown below.

In fig. 11 to 15, the area D1 represents an area having an x coordinate of 0.0mm to 40.0mm, and the area D2 represents an area having an x coordinate of 260.0mm to 300.0 mm. In addition, the region D3 represents a region having an x-coordinate of 0.0mm to 40.0mm, and the region D4 represents a region having an x-coordinate of 260.0mm to 300.0 mm.

< example 1>

As shown in fig. 10, the projection apparatus 1 according to example 1 is configured to include a diffractive optical element 20 and a lens 30 having a curvature only in the y direction, and to have a beam diameter of incident light in the same manner as the projection apparatus shown in fig. 1

Was set at 7200.0. Mu.m.

In example 1, the structure of the uneven pattern layer 25, pitches Px and Py, lens distance ZL, focal length f, and the like in the diffractive optical element 20 were optimized, and as a result, the distortion ∈ was 63.0 μm or less, and the line width LW was 98.0 μm or less. The light spot length Qy is 1/205 of the light spot length Qx. Note that ZL = ZS-f is always satisfied at a lens distance ZL at which all diffracted light generated by the diffractive optical element 20 enters the lens 30.

As shown in fig. 11, in each of the regions D1 to D4, the splitting and the deformation are suppressed, and the linear pattern L with good quality is obtained. Here, the division of the line pattern L means that the line pattern L is divided into a plurality of independent portions.

< example 2>

As shown in fig. 10, the projection apparatus 1X2 of example 2 has a structure including a diffractive optical element 20X2 without a lens, and has a beam diameter of an incident beam

Set to 100.0 μm. The strain [ epsilon ] is 4053.0 μm or less, and the line width LW is 4153.0 μm or less. The bright point length Qy is equal to the bright point length Qx.

As shown in fig. 12, the linear pattern L in each area is a linear pattern of the bright spots Ls divided into a plurality of dots. Although the light spot lengths Qx and Qy are 100.0 μm, the line width LW becomes thicker than in example 1 as a result of a large positional shift of the light spot Ls due to the distortion e as in the case of the area D2.

< example 3>

As shown in fig. 10, the projection apparatus 1X3 of example 3 has a structure including a diffractive optical element 20X3 without a lens, and has a beam diameter of an incident beam

Set to 800.0 μm. The strain [ epsilon ] is 546.0 μm or less, and the line width LW is 1346.0 μm or less. The light spot length Qy is equal to the light spot length Qx.

As shown in fig. 13, in the line pattern L of each regionNo splitting is observed, but positional shift such as undulation becomes large. In addition, with incident beam diameter

When the size is increased, the linear pattern L becomes thicker as a whole than in example 1.

< example 4>

As shown in fig. 10, the projection apparatus 1X4 according to example 4 has a configuration including a diffractive optical element 20X4 and a lens 30X4 having a curvature only in the X direction, and has a beam diameter of an incident beam

Set to 100.0 μm. The strain [ epsilon ] is 3762.0 μm or less, and the line width LW is 3862.0 μm or less. The light spot length Qy is 1/100 of the light spot length Qx.

As shown in fig. 14, in the line pattern L of the area D2, a large positional shift and a split are generated. Although each of the line patterns L itself becomes thin, the line width LW becomes thicker as compared with example 1 as a result of a large positional shift.

< example 5>

As shown in fig. 10, the projection apparatus 1X5 according to example 5 has a configuration including a lens 30X5 having a curvature only in the X direction and a diffractive optical element 20X5 disposed on the projection surface S side of the lens 30X5, and has a beam diameter of incident light

Set to 100.0 μm. The strain [ epsilon ] is 3882.0 μm or less, and the line width LW is 3982.0 μm or less. The light spot length Qy is 1/102 of the light spot length Qx.

As shown in fig. 15, in the line pattern L of the region D2, a large positional shift and a split are generated. Although each of the linear patterns L itself becomes thin, the line width LW becomes thicker as compared with example 1 as a result of a large positional shift of the bright point Ls.

From the above results, in examples 1 to 5, the configuration of the projection apparatus 1 according to example 1 is more preferable in order to project the linear pattern L having a narrow line width LW and good quality.

Next, examples 6 to 11 will be described. In examples 6 to 11, as in the projection apparatus 1 according to example 1, a configuration including the diffractive optical element 20 and the lens 30 having a curvature only in the y direction was adopted, and the numerical values of the respective specifications were changed from those of example 1.

FIG. 16 is a graph showing the specifications and evaluation results of examples 6 to 8. FIG. 17 is a graph showing the specifications and evaluation results of examples 9 to 11. Fig. 18 to 23 are diagrams illustrating simulation results of line 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.

In fig. 18 to 23, the area D1 represents an area having an x coordinate of 0.0mm to 40.0mm, and the area D3 represents an area having an x coordinate of 0.0mm to 40.0mm.

In fig. 18, 19 and 22, the area D2 represents an area having an x coordinate of 260.0mm to 300.0mm, and the area D4 represents an area having an x coordinate of 260.0mm to 300.0 mm.

In fig. 20, the area D2 represents an area having an x-coordinate of 300.0mm to 340.0mm, and the area D4 represents an area having an x-coordinate of 300.0mm to 340.0 mm.

In fig. 21, the area D2 represents an area having an x-coordinate of 110.0mm to 150.0mm, and the area D4 represents an area having an x-coordinate of 110.0mm to 150.0 mm.

In fig. 23, a region D2 represents the line pattern L5 in a region with an x-coordinate of 130.0mm to 170.0mm, and a region D4 represents the line pattern L1 in a region with an x-coordinate of 130.0mm to 170.0 mm.

< example 6>

As shown in fig. 16, in example 6, the number Ln of lines was changed to 20 compared to example 1. As shown in fig. 16 and 18, in example 6, the distortion ∈ and the line width LW were not changed from those of example 1.

< example 7>

As shown in fig. 16, in example 7, the pitches Px and Py of the basic cells in the diffractive optical element 20 were changed from those in example 1. In example 7, as a result of changing the line width LW to about 2 times that of example 1, 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 was thicker than that in example 1. The light spot length Qy is 1/51 of the light spot length Qx. As shown in fig. 19, no splitting or deformation was observed in the line pattern L in each evaluation area, and a line pattern L with good quality was obtained.

< example 8>

As shown in FIG. 16, in example 8, the incident beam diameter was set to be larger than that of example 1

The pitch Px and Py of the basic cells and the diffraction divergence angles θ x and θ y in the diffractive optical element 20 were changed to 8000.0 μm. In example 8, as a result of changing the diffraction divergence angles θ x and θ y compared to example 1, the incident beam diameter was changed, and the pitches Px and Py were also changed. The strain ε was 68.0 μm, and the linewidth LW was 100.0. Mu.m, which was substantially the same as that in example 1. The bright point length Qy is 1/250 of the bright point length Qx. As shown in fig. 20, no splitting or deformation was observed in each evaluation region, and a linear pattern L of good quality was obtained.

< example 9>

As shown in FIG. 17, in example 9, the incident beam diameter was set to be larger than that of example 1

The pitch Px and Py of the basic cells in the diffractive optical element 20 and the focal length f of the lens 30 were changed to 3600.0. Mu.m. In example 9, as a result of changing the projection distance ZS as compared with example 1, the focal length f was changed, 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 was substantially the same as that of 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 deformation was observed, and a linear pattern L with good quality was obtained. The light spot length Qy is 1/103 of the light spot length Qx.

< example 10>

As shown in FIG. 17, in example 10, the wavelength λ was changed to 850.0nm and the incident beam diameter was changed to that of example 1

The pitch Px and Py of the basic cells in the diffractive optical element 20 were changed to 15200.0 μm. In example 10, as compared with example 1, the incident beam diameter was changed by changing the wavelength λ, and the pitches Px and Py were also changed. The strain ε was 64.0 μm, and the linewidth LW was 99.0. Mu.m, which was approximately the same as that in example 1. The light spot length Qy is 1/434 of the light spot length Qx. As shown in fig. 22, no splitting or deformation was observed in each evaluation region, and a linear pattern L of good quality was obtained.

< example 11>

As shown in FIG. 17, in example 11, the wavelength λ was changed to 850.0nm and the incident beam diameter was changed to that of example 1

The pitch Px and Py of the basic cells in the diffractive optical element 20 and the diffraction divergence angles θ x and θ y were changed to 4200.0 μm. In example 11, the focal length f was changed and the incident beam diameter and pitches Px and Py were also changed as a result of changing all the parts changed in examples 6 to 10 from example 1. The distortion ε was 132.0 μm, and the line width LW was 195.0 μm, which was thicker than that in example 1. The light point length Qy is 1/67 of the light point length Qx. As shown in fig. 23, no splitting or deformation was observed in each evaluation region, and a line pattern L with good quality was obtained.

As described above, from the results shown in fig. 16 to 23, it is understood that the linear patterns L having a small line width LW and good quality can be projected in examples 6 to 11. From the viewpoint of making the line width LW thin, it is found that the line width LW is preferably 250.0 μm or less, more preferably 100.0 μm or less.

Further, the light spot length Qy needs to be reduced as the line width LW is made thinner, and the incident beam diameter R needs to satisfy the following two equations when the specification value of the line width LW is LT.

R≥(4×λ×f)/(π×LT)…(4)

R≥√(Px ² +Py ² )…(5)

As a result, the narrower the line width LW, the larger the pitches Px and Py can be, and therefore, the bright point interval and distortion can be reduced. Even if the line width varies, the ratio of the bright point interval and the distortion with respect to the line width LW is substantially constant, and therefore, from the viewpoint of improving the quality of the line width LW, it can be considered to be substantially constant without depending on the line width LW.

Here, the minimum line width LW that can be achieved by the diffractive optical element 20 alone is examined, and it is found that the line width LW is influenced in the following manner.

Wavelength λ: the longer the line width LW.

Projection distance ZS: the longer the line width LW.

Diffraction divergence angle θ x: the wider the angle, the larger the line width LW.

Diffraction divergence angle θ y: the wider the angle, the larger the line width LW.

Length of the line pattern L along the x direction: the shorter the line width LW, the easier it is.

In the case where one line pattern L is projected, the line width LW is minimum.

In view of these circumstances, the line width LW is calculated from a practical specification in which the line width LW is easily reduced, and as a result, it is found that the line width LW is preferably 250.0 μm or less.

< effects of the projector apparatus 1>

As described above, the projection apparatus 1 includes: a light source 10 emitting parallel light; a diffractive optical element 20 disposed on the side of the light source 10 from which the parallel light is emitted; and a lens 30 disposed on the opposite side of the diffractive optical element 20 from the light source 10 and having a curvature in the y direction (predetermined direction). The lens 30 generates a plurality of bright spots Ls aligned in the x direction (direction perpendicular to the predetermined direction) on the projection surface S, thereby projecting the linear pattern L extending in the x direction onto the projection surface S. The bright point length Qx (the length of the bright point along the x direction) is equal to or longer than the bright point interval Vx (the interval along the x direction between adjacent bright points in the plurality of bright points), and the bright point length Qy (the length of the bright point along the y direction) of all of the plurality of bright points Ls is shorter than the bright point length Qx. In all of the plurality of light spots Ls, the light spot length Qy and the light spot length Qx satisfy the relationship of the above expression (3).

By making the bright point length Qx longer than the length of the bright point interval Vx, a high-quality linear pattern L in which the splitting is suppressed and the deformation is suppressed can be projected. In addition, by making the bright point length Qy shorter than the bright point length Qx, the line width LW of the linear pattern L extending in the x direction can be made narrow. As a result, the projection apparatus 1 capable of projecting the linear pattern L having a narrow line width LW and good quality can be provided.

In the projection apparatus described in patent document 1, the smaller the diameter of the incident light to the diffractive optical element, the larger the distance between the plurality of bright points generated on the projection surface by the diffracted light generated by the diffractive optical element and the larger the positional deviation of the bright points caused by distortion. The smaller the pitches Px and Py, the larger the spot spacing and distortion. When the diameter of incident light is R, the pitches Px and Py need to satisfy the following expression.

R≥√(Px ² +Py ² )

In the case of a single diffractive optical element, the diameter of the incident light needs to be equal to the diameter of the bright spot. Therefore, in order to make the line width small with the diffractive optical element alone, it is necessary to reduce the diameter of incident light. As a result, the smaller the diameter of the incident light, the larger the positional deviation, which is due to the small pitch.

From the viewpoint of making the line width LW of the linear pattern L narrower, the bright point length Qy of the plurality of bright points Ls is preferably 1/50 or less of the bright point length Qx. The light spot length Qy is more preferably 250.0 μm or less, and still more preferably 100.0 μm or less.

In the present embodiment, the lens 30 projects the plurality of line patterns L onto the projection surface S, and the plurality of line patterns L are parallel to each other. For example, when the projection apparatus 1 is applied to a sensing application or the like and the linear pattern L is projected as probe light from the projection apparatus 1, the probe light can be irradiated over a wider range with high spatial resolution.

In this embodiment, the cross-sectional shape of the laser beam (parallel light) in a plane orthogonal to the central axis of the laser beam is substantially circular. This can suppress the anisotropy of diffraction of the diffractive optical element 20.

In the present embodiment, the diffractive optical element 20 includes a plurality of groupsThis unit 21. The plurality of basic units 21 have the same concave-convex pattern layer 25, are arranged at a predetermined pitch Px at least along the x direction, and have incident beam diameters

Is larger than the pitch Px. When the specification value of the line width LW is LT, the diameter of the laser beam is independent of the number Ln of lines, and the above-described expressions (1) and (2) are satisfied. With this configuration, one laser beam incident on the diffractive optical element 20 can be efficiently diffracted in the x direction by using the entire basic unit 21.

In the present embodiment, the diffractive optical element 20 emits substantially parallel laser beams (parallel light beams), and the lens 30 receives the substantially parallel laser beam light 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 line pattern L on the projection surface S, and thus the degree of freedom in component arrangement and the like in the projection apparatus 1 can be increased.

While the preferred embodiments have been described in detail, the present invention is not limited to the above embodiments, and various modifications and substitutions can be made to the above embodiments without departing from the scope of the present invention as defined by the appended claims.

The projector according to the embodiment can be applied to various fields such as Light sensing using Light such as Light Detection And Ranging (Light based distance Detection), and optical methods used in image projectors such as projectors.

Description of the reference symbols

1. A projection device;

10. a light source;

20. a diffractive optical element;

21. a base unit;

22. a light-transmissive member;

23. a convex portion;

24. a recess;

25. a concave-convex pattern layer;

30. a lens;

an L-shaped line pattern;

s, a projection surface;

px, py spacing;

thetax, thetay diffraction divergence angles;

ZL lens distance;

ZS projection distance;

ls bright spot;

an LW line width;

interval of bright spots Vx and Vy;

qx, qy spot length;

epsilon deformation;

d1, D2, D3, D4 regions;

f, focal length;

the incident beam diameter.

Claims (8)

1. A projection device is provided with:

a light source emitting parallel light;

a diffractive optical element disposed on a side of the light source from which the parallel light is emitted; and

a lens disposed on a side of the diffractive optical element opposite to the light source and having a curvature in a predetermined direction,

the lens generates a plurality of bright spots arranged in a direction perpendicular to the predetermined direction on a projection surface, thereby projecting a linear pattern extending in the perpendicular direction onto the projection surface,

a length of the bright spots along the vertical direction is a length of an interval of adjacent ones of the bright spots from each other along the vertical direction or more,

the length of the bright point along the prescribed direction of all of the plurality of bright points is shorter than the length of the bright point along the perpendicular direction.

2. The projection apparatus according to claim 1,

the length of the bright point in the predetermined direction of the plurality of bright points is 1/50 or less of the length of the bright point in the perpendicular direction.

3. The projection apparatus according to claim 1 or 2,

the length of the bright point along the predetermined direction is 250 μm or less.

4. The projection apparatus according to any one of claims 1 to 3,

the length of the bright point along the predetermined direction is 100 μm or less.

5. The projection apparatus according to any one of claims 1 to 4,

the lens projects the plurality of line patterns onto the projection surface,

the plurality of linear patterns are parallel to each other.

6. The projection apparatus according to any one of claims 1 to 5,

the cross-sectional shape of the parallel light in a plane orthogonal to the central axis of the parallel light is substantially circular.

7. The projection apparatus according to claim 6,

the diffractive optical element comprises a plurality of elementary cells,

the plurality of basic units have the same concavo-convex pattern layer and are arranged at a predetermined pitch at least along the vertical direction,

the diameter of the substantially circular shape in the cross-sectional shape of the parallel light is larger than the pitch.

8. The projection apparatus according to any one of claims 1 to 7,

the diffractive optical element emits parallel light,

the lens is configured to receive the parallel light emitted from the diffractive optical element.

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