Illumination system, illumination light observation system, illumination light imaging system, illumination device, and method for designing illumination system

Abstract

An illumination system (30) is provided with a projection surface (40) and an illumination device (50). The projection surface (40) is parallel to the first direction (D1) and a second direction (D2) orthogonal to the first direction (D1). An illumination device (50) projects a projection pattern (41) extending in a first direction (D1) onto a projection surface (40). An illumination device (50) has a light source (51) and a diffractive optical element (55) that diffracts light from the light source (51) and forms a projection pattern (41). The diffractive optical element (55) includes a plurality of element diffractive optical elements (56) each diffracting light from the light source (51). The minimum length (Lb1) of the lengths of the projection pattern (41) in the second direction (D2) is shorter than the maximum length (Lc) of the lengths at which the light incident on the diffractive optical element (55) intersects a plane parallel to the projection plane (40), and is longer than the maximum length (La) of the lengths at which the element diffractive optical element (56) intersects a plane parallel to the projection plane (40).

Description

Technical Field

[0001] The present disclosure relates to an illumination system, an illumination light observation system having the illumination system, an illumination light imaging system having the illumination system, an illumination device, and a design method of the illumination system. Background Art

[0002] As described in Japanese Patent Application Laid-Open No. 2015-162424, there is known a lighting device that projects a projection pattern onto a projection surface such as a road surface. For example, in order to perform work on a road surface, a projection pattern having a linear shape extending in one direction is projected by the lighting device.

[0003] It is required to narrow the width of the projection pattern extending in one direction. If the width of the projection pattern is narrowed, the light used to project the projection pattern is concentrated in a narrow range. Thus, the projection pattern can be observed brightly. Even if there is a lot of ambient light, the projection pattern can be easily identified. By narrowing the width of the projection pattern, the error in determining the center of the line shown by the projection pattern is reduced. By narrowing the width of the projection pattern, the line shape of the projection pattern can be easily and accurately identified. Summary of the invention

[0004] Sometimes, light projected from an illumination device at a very close distance is to be observed. If the light used to project a projection pattern is concentrated in a narrow range, high-intensity light enters the eyes when the light projected from the illumination device at a very close distance is observed. This is not preferred for eye safety. The present disclosure aims to reduce the intensity of light at a very close distance while narrowing the width of a projection pattern extending in one direction.

[0005] The lighting system disclosed in the present invention has:

[0006] a projection plane parallel to the first direction and a second direction orthogonal to the first direction; and

[0007] an illumination device that projects a projection pattern extending in the first direction onto the projection surface,

[0008] The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern.

[0009] The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source.

[0010] The minimum length of the projection pattern in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface.

[0011] According to the present disclosure, it is possible to reduce the intensity of light at an extremely close distance while narrowing the width of a projection pattern extending in one direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a perspective view showing an example of the illumination light observation system according to the first embodiment.

[0013] Figure 2 It is a perspective view showing an observer wearing an observation assisting device.

[0014] Figure 3 It is a top view showing an example of the lighting system according to the first embodiment.

[0015] Figure 4 This is a perspective view showing an example of the lighting device according to the first embodiment.

[0016] Figure 5 This is a diagram of the diffractive optical element according to the first embodiment as viewed from the first direction.

[0017] Figure 6 This is a side view showing an example of the lighting device according to the first embodiment.

[0018] Figure 7 This is a plan view showing a modified example of the lighting system according to the first embodiment.

[0019] Figure 8 Observed from the first direction Figure 7 Diagram of the diffractive optical element of the illumination system shown.

[0020] Fig. 9 It is a side view showing an example of the illumination light imaging system according to the second embodiment.

[0021] Fig.10 It is shown Fig. 9 A top view of a display device of the illumination light camera system shown.

[0022] Fig.11 This is a perspective view showing an example of a lighting device according to a third embodiment.

[0023] Fig.12 This is a diagram of the optical element according to the third embodiment as viewed from the first direction. DETAILED DESCRIPTION

[0024] One embodiment of the present disclosure will be described with reference to the accompanying drawings. In the drawings attached to this specification, for the sake of convenience of illustration and understanding, the scale and aspect ratio may be appropriately changed and exaggerated from the actual object.

[0025] Terms such as "parallel", "orthogonal", "same", etc., or values ​​of lengths and angles used in this specification to determine shapes, geometric conditions and their degrees are not limited to strict meanings but are interpreted within a range that includes the degree to which the same function can be expected.

[0026] The embodiments and modifications of the present disclosure relate to the following [1] to

[18] . [1]

[0028] A lighting system, wherein

[0029] The lighting system comprises:

[0030] a projection plane parallel to the first direction and a second direction orthogonal to the first direction; and

[0031] an illumination device that projects a projection pattern extending in the first direction onto the projection surface,

[0032] The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern.

[0033] The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source.

[0034] The minimum length of the projection pattern in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface. [2]

[0036] A lighting system, wherein

[0037] The lighting system comprises:

[0038] a projection plane parallel to the first direction and a second direction orthogonal to the first direction; and

[0039] an illumination device that projects a projection pattern extending in the first direction onto the projection surface,

[0040] The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern.

[0041] The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source.

[0042] The length of the projection pattern at the end portion on one side close to the lighting device in the first direction in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface. [3]

[0044] A lighting system, wherein

[0045] The lighting system comprises:

[0046] a projection plane parallel to the first direction and a second direction orthogonal to the first direction; and

[0047] an illumination device that projects a projection pattern extending in the first direction onto the projection surface,

[0048] The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern.

[0049] The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source.

[0050] The length of the projection pattern in the second direction at the position where the illumination is maximum is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface. [4]

[0052] The lighting system according to any one of [1] to [3], wherein:

[0053] The light incident on the diffractive optical element is wider in the direction of a line where the diffractive optical element intersects a surface parallel to the projection surface than in a third direction which is not parallel to the projection surface.

[0054] The light diffracted by the diffractive optical element spreads in the third direction more than the direction of a line intersecting the diffractive optical element and a surface parallel to the projection surface. [5]

[0056] The lighting system according to any one of [1] to [4], wherein:

[0057] The length of the light incident on the diffractive optical element in the direction of a line intersecting the diffractive optical element and a surface parallel to the projection surface is 7 mm or more. [6]

[0059] The lighting system according to any one of [1] to [5], wherein:

[0060] In a third direction not parallel to the projection plane, radiation intensity of light diffracted by the diffractive optical element is higher at a position far from the projection plane than near the projection plane. [7]

[0062] A lighting system, wherein

[0063] The lighting system comprises:

[0064] a projection plane parallel to the first direction and a second direction orthogonal to the first direction; and

[0065] an illumination device that projects a projection pattern extending in the first direction onto the projection surface,

[0066] The lighting device comprises: a light source; and an optical element, which acts on the light from the light source to form the projection pattern.

[0067] The minimum length of the projection pattern in the second direction is shorter than the maximum length of the length of light incident on the optical element intersecting the surface parallel to the projection surface. [8]

[0069] An illumination light observation system, wherein:

[0070] The illumination light observation system comprises:

[0071] The lighting system described in any one of [1] to [7]; and

[0072] An optical filter having an average transmittance at a wavelength of light projected by the lighting device onto the projection surface that is higher than an average transmittance at other wavelengths. [9]

[0074] An illumination light camera system, wherein:

[0075] The illumination light imaging system comprises:

[0076] The lighting system described in any one of [1] to [7]; and

[0077] A camera device is used to capture the projection pattern.

[10]

[0079] The illumination light imaging system according to [9], wherein:

[0080] The imaging device includes an optical filter having an average transmittance at a wavelength of light projected by the illumination device onto the projection surface higher than an average transmittance at other wavelengths.

[11]

[0082] A lighting device projects a projection pattern extending in a first direction onto a projection surface parallel to a first direction and a second direction orthogonal to the first direction, wherein:

[0083] The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern.

[0084] The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source.

[0085] The minimum length of the projection pattern in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface.

[12]

[0087] A lighting device projects a projection pattern extending in a first direction onto a projection surface parallel to a first direction and a second direction orthogonal to the first direction, wherein:

[0088] The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern.

[0089] The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source.

[0090] The length of the projection pattern at the end portion on one side close to the lighting device in the first direction in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface.

[13]

[0092] A lighting device projects a projection pattern extending in a first direction onto a projection surface parallel to a first direction and a second direction orthogonal to the first direction, wherein:

[0093] The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern.

[0094] The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source.

[0095] The length of the projection pattern in the second direction at the position where the illumination is maximum is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface.

[14]

[0097] A lighting device projects a projection pattern extending in a first direction onto a projection surface parallel to a first direction and a second direction orthogonal to the first direction, wherein:

[0098] The lighting device comprises: a light source; and an optical element, which acts on the light from the light source to form the projection pattern.

[0099] The minimum length of the projection pattern in the second direction is shorter than the maximum length of the length of light incident on the optical element intersecting the surface parallel to the projection surface.

[15]

[0101] A method for designing an illumination system, wherein the illumination system projects a projection pattern extending in a first direction onto a projection plane parallel to the first direction and in a second direction orthogonal to the first direction through an illumination device including a diffractive optical element, wherein:

[0102] The design method of the lighting system comprises the following steps:

[0103] Determining the diffraction characteristics of the diffractive optical element in such a manner that the minimum length of the projection pattern in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface; and

[0104] The diffraction characteristics of the element diffractive optical element are determined in such a way that the minimum length of the projection pattern in the second direction is longer than the maximum length of the intersection of multiple element diffractive optical elements included in the diffractive optical element and the surface parallel to the projection surface.

[16]

[0106] A method for designing an illumination system, wherein the illumination system projects a projection pattern extending in a first direction onto a projection plane parallel to the first direction and in a second direction orthogonal to the first direction through an illumination device including a diffractive optical element, wherein:

[0107] The design method of the lighting system comprises the following steps:

[0108] The diffraction characteristic of the diffractive optical element is determined in such a manner that the length of the projection pattern at the end portion on one side close to the lighting device in the first direction in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface; and

[0109] The diffraction characteristics of the elemental diffractive optical element are determined in such a manner that the length of the projection pattern at the end portion of the side close to the lighting device in the first direction in the second direction is longer than the maximum length of the intersection of multiple elemental diffractive optical elements included in the diffractive optical element and the surface parallel to the projection surface.

[17]

[0111] A method for designing an illumination system, wherein the illumination system projects a projection pattern extending in a first direction onto a projection plane parallel to the first direction and in a second direction orthogonal to the first direction through an illumination device including a diffractive optical element, wherein:

[0112] The design method of the lighting system comprises the following steps:

[0113] The diffraction characteristic of the diffractive optical element is determined in such a manner that the length of the projection pattern in the second direction at the position where the illumination is maximum is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface; and

[0114] The diffraction characteristics of the element diffractive optical element are determined in such a way that the length of the projection pattern in the second direction at the position where the illumination is maximum is longer than the maximum length of the intersection of multiple element diffractive optical elements included in the diffractive optical element and the surface parallel to the projection surface.

[18]

[0116] A method for designing an illumination system, wherein the illumination system projects a projection pattern extending in a first direction onto a projection surface parallel to a first direction and a second direction orthogonal to the first direction by means of an illumination device comprising an optical element, wherein:

[0117] The design method of the lighting system includes the following steps: determining the optical characteristics of the optical element in such a way that the minimum length of the projection pattern in the second direction is shorter than the maximum length of the intersection of the light incident on the optical element and the surface parallel to the projection surface.

[0118] <First Embodiment>

[0119] Figure 1 1 is a perspective view showing the illumination light observation system of the first embodiment. Figure 1 As shown, the illumination light observation system 10 of the first embodiment includes an illumination system 30 and an observation assisting device 11. The illumination system 30 includes a projection surface 40 and an illumination device 50. The illumination device 50 emits light to project a projection pattern 41 onto the projection surface 40. The observer 5 can observe the projection pattern 41 projected onto the projection surface 40. The observer 5 wears the observation assisting device 11.

[0120] The observation assisting device 11 includes a wearing member 13 and an optical filter 15. The wearing member 13 enables the observer 5 to easily wear the observation assisting device 11. The wearing member 13 can hold the optical filter 15. When the observer 5 wears the observation assisting device 11, the optical filter 15 faces the eyes of the observer 5. The observer 5 wearing the observation assisting device 11 observes the projection pattern 41 via the optical filter 15.

[0121] exist Figure 1 In the example shown, the wearing member 13 is glasses. Without being limited to the example shown in the figure, the wearing member 13 may be in any form as long as the optical filter 15 can be arranged to face the eyes of the observer. For example, the wearing member 13 may be goggles or contact lenses.

[0122] Regarding the optical filter 15, the average transmittance in a specific wavelength region is higher than the average transmittance in other wavelength regions. In the illumination light observation system 10, regarding the optical filter 15, the average transmittance at the wavelength of the light projected by the illumination device 50 onto the projection surface 40 is higher than the average transmittance at other wavelengths. The average transmittance of the optical filter 15 at the wavelength of the light projected by the illumination device 50 onto the projection surface 40 may be 50% or more, 70% or more, or 80% or more. The average transmittance of the optical filter 15 at the wavelength of the light projected by the illumination device 50 onto the projection surface 40 may be 100% or less, or 90% or less. The average transmittance of the optical filter 15 at wavelengths other than the wavelength of the light projected by the illumination device 50 onto the projection surface 40 may be 1% or less, 0.1% or less, or 0.01% or less. The optical filter 15 selectively transmits the light projected by the illumination device 50 onto the projection surface 40.

[0123] The transmittance refers to the total light transmittance measured at an incident angle of 0° using a spectrophotometer ("UV-Visible Infrared Spectrophotometer UV-3100PC" manufactured by Shimadzu Corporation) in accordance with JIS K 0115. The average transmittance is the average value of the transmittance measured per 1 nm in the visible light wavelength region. The wavelength region of visible light is 380 nm or more and 780 nm or less.

[0124] Preferably, the wavelength region of the light projected by the illumination device 50 is narrow enough so that the optical filter 15 can selectively transmit the light projected by the illumination device 50. The light projected by the illumination device 50 may also be coherent light.

[0125] The projection surface 40 is a display surface that displays the projection pattern 41 projected from the lighting device 50 in a manner that can be observed by the observer 5. The projection surface 40 is separated from the lighting device 50. The projection surface 40 is preferably a flat surface so that the projection pattern 41 can be properly displayed. Figure 1 As shown, the projection plane 40 is a plane parallel to the first direction D1 and the second direction D2. The second direction D2 is orthogonal to the first direction D1. The projection plane 40 may be, for example, a road surface, a sidewalk, a ground surface of a sports field, a park, etc., a water surface such as the sea surface, an outer wall surface, an inner wall surface, a passage, a floor, or a part of a ceiling of a building such as a school, a company, a building, a factory, a meeting place, a lecture hall, a gymnasium, an arena, or a conference hall.

[0126] The projection pattern 41 is projected onto the projection plane 40 and is observed by the observer 5. The projection pattern 41 includes light in the wavelength region of visible light so as to be observed by the observer 5. The projection pattern 41 extends in the first direction D1. Figure 3 4 is a top view showing a projection pattern 41 projected from the lighting device 50 onto the projection surface 40. Figure 3 As shown, the projection pattern 41 has a linear shape with the first direction D1 as the long side direction. The length of the projection pattern 41 in the first direction D1 is longer than the maximum length of the lengths in the second direction D2. For example, the length of the projection pattern 41 in the first direction D1 is more than 50 times the maximum length of the projection pattern 41 in the second direction D2. The length of the projection pattern 41 in the first direction D1 is, for example, more than 1m and less than 200m. The length of the projection pattern 41 in the second direction D2 is, for example, more than 1mm and less than 50mm.

[0127] The length of the projection pattern 41 in the first direction D1 is determined as follows. The maximum illumination position Pmax at which the illumination is the maximum in the projection pattern 41 is determined. The position at which the illumination of the projection pattern 41 becomes 2% of the maximum illumination is determined as the first end E1, approaching the lighting device 50 from the maximum illumination position Pmax along the first direction D1. At the position at which the illumination is 2% of the maximum illumination, the illumination is too low and the projection pattern 41 cannot be observed. The portion at which the illumination is 2% or more of the maximum illumination is observed as the projection pattern 41. The first end E1 is the end of the projection pattern 41 on the side close to the lighting device 50 in the first direction D1. The position at which the illumination of the projection pattern 41 becomes 2% of the maximum illumination is determined as the second end E2, moving away from the lighting device 50 from the maximum illumination position Pmax along the first direction D1. The second end E2 is the end of the projection pattern 41 on the side away from the lighting device 50 in the first direction D1. The length between the first end E1 and the second end E2 is the length of the projection pattern 41 in the first direction D1. The projection pattern 41 extends between the first end portion E1 and the second end portion E2 in the first direction D1.

[0128] The length of the projection pattern 41 in the second direction D2 can be determined at each position along the first direction D1. The length of the projection pattern 41 in the second direction D2 is determined as follows. The second direction maximum illumination position where the illumination of the projection pattern 41 becomes maximum along the second direction D2 is determined. The illumination of the projection pattern 41 is determined along the second direction D2 from the second direction maximum illumination position to become 1 / e of the maximum illumination. 2 The length between the two ends is the length of the projection pattern 41 in the second direction D2. The length of the projection pattern 41 in the second direction D2 is the width of the projection pattern 41.

[0129] e is Napier's constant.

[0130] The illuminance is a value measured using an illuminometer (“Spectroradiometer CL-500A” manufactured by Konica Minolta) in accordance with JIS C 1609-1:2006.

[0131] The lighting device 50 projects a projection pattern 41 onto the projection surface 40 using light emitted from the emission portion 50a. Figure 1 In the example shown, the lighting device 50 is fixed by a tripod. The lighting device 50 may also be movable. The lighting device 50 may also be applied to a moving object such as a vehicle, a ship, an airplane, or a train.

[0132] Figure 4 is a perspective view showing an example of the structure of the lighting device 50. Figure 4As shown, the lighting device 50 includes a light source 51, a shaping optical system 53, and a diffractive optical element 55. The lighting device 50 may further include a housing for housing the light source 51, the shaping optical system 53, and the diffractive optical element 55.

[0133] The light source 51 emits, for example, coherent light, which is light of the same wavelength and phase. Coherent light has excellent straightness. When the lighting device 50 projects the projection pattern 41 onto the distant projection surface 40, the light source 51 preferably emits coherent light. The light source 51 that emits coherent light may also be a laser light source that oscillates laser light. The light source 51 may also be a semiconductor laser light source. Figure 4 In the example shown, the light source 51 includes a single coherent light source. Coherent light of a color corresponding to the wavelength of the coherent light oscillated from the light source 51 is projected from the lighting device 50 onto the projection surface 40. Not limited to the example shown in the figure, the light source 51 may also include a plurality of coherent light sources. For example, the light source 51 may also oscillate coherent light of wavelengths of red, green, and blue.

[0134] The shaping optical system 53 shapes the light emitted from the light source 51. The shaping optical system 53 shapes the shape of the cross section perpendicular to the optical axis of the light from the light source 51 or the three-dimensional shape of the light. The shaping optical system 53 may also enlarge the cross-sectional area of ​​the light in the cross section perpendicular to the optical axis of the light. Figure 4 In the example shown, the shaping optical system 53 shapes the light emitted from the light source 51 into expanded parallel light. The shaping optical system 53 functions as a collimating optical system. Figure 4 In the example shown, the shaping optical system 53 has a first shaping lens 53a and a second shaping lens 53b arranged along the optical path. The first shaping lens 53a shapes the light emitted by the light source 51 into divergent light. The second shaping lens 53b shapes the divergent light generated by the first shaping lens 53a into parallel light. The second shaping lens 53b functions as a collimating lens. The light shaped by the shaping optical system 53 is incident on the diffractive optical element 55.

[0135] The diffractive optical element 55 diffracts the light that has passed through the shaping optical system 53 to form a projection pattern 41. The light diffracted by the diffractive optical element 55 is projected onto the projection plane 40. The projection pattern 41 has a shape corresponding to the diffraction pattern of the diffractive optical element 55. The diffractive optical element 55 is designed so as to project a desired projection pattern 41.

[0136] like Figure 4As shown, the diffractive optical element 55 includes a plurality of element diffractive optical elements 56. The element diffractive optical element 56 is a tiny thin plate-shaped component. A plurality of element diffractive optical elements 56 are arranged two-dimensionally without gaps on the same plane in the diffractive optical element 55. The element diffractive optical element 56 diffracts light. The light diffracted by the element diffractive optical element 56 is emitted from the emission portion 50a. The plurality of element diffractive optical elements 56 diffract the light from the shaping optical system 53 respectively. The light diffracted by each element diffractive optical element 56 is projected onto the projection surface 40 to form a projection pattern 41. The light diffracted by each element diffractive optical element 56 can form the entire projection pattern 41 or can form it part by part. The light diffracted by the diffractive optical element 55 is dispersed by the element diffractive optical element 56 and emitted from the emission portion 50a. It is possible to suppress each position of the diffractive optical element 55 from becoming too bright, thereby improving the safety of the laser.

[0137] The element diffractive optical element 56 is, for example, a hologram element. If the element diffractive optical element 56 is a hologram element, the diffraction characteristics of the element diffractive optical element 56 can be easily designed.

[0138] The element diffractive optical element 56 can be made into a computer generated hologram (CGH). For a computer generated hologram, a structure having arbitrary diffraction characteristics is calculated on a computer to make it. When the element diffractive optical element 56 is a computer generated hologram, it is possible to generate object light and reference light without using a light source or an optical system, or to record interference fringes on a hologram recording material by exposure. It is envisioned that the lighting device 50 projects a projection pattern 41 on a projection surface 40 at a predetermined position relative to the lighting device 50 with a predetermined contour shape, size, and orientation. By inputting information related to the projection surface 40 as parameters into the computer, a structure having diffraction characteristics capable of projecting diffracted light onto the projection surface 40, such as a concave-convex surface, can be determined by calculations in the computer. By forming the determined structure using, for example, resin molding, the element diffractive optical element 56 as a computer generated hologram can be produced at low cost with simple steps.

[0139] In the design of the element diffractive optical element 56, for example, an iterative Fourier transform method may be used. When the iterative Fourier transform method is used, the projection plane 40 may be processed on the premise that it is far away from the element diffractive optical element 56, and the projection pattern 41 projected onto the projection plane 40 may be set as a Fraunhofer diffraction image. In this case, the projection plane 40 may not be parallel to the diffraction plane of the element diffractive optical element 56.

[0140] Figure 5This is a diagram of the diffractive optical element 55 in the emission portion 50 a as viewed from the first direction D1 . Figure 5 The oblique line portion of represents the portion where light is incident on the diffractive optical element 55. Figure 5 As shown in FIG. 1 , the light incident on the diffractive optical element 55 is wider in the direction of the line where the diffractive optical element 55 intersects the surface parallel to the projection surface than in the third direction D3. Figure 5 In the example shown, the direction of the line where the diffractive optical element 55 intersects the plane parallel to the projection plane is consistent with the second direction D2. The third direction D3 is a direction that is not parallel to the projection plane 40. The third direction D3 is a direction that is not parallel to the first direction D1 and the second direction D2. The third direction D3 may also be a direction that is inclined toward the first direction D1 and is orthogonal to the second direction D2. Figure 5 In the example shown, the light incident on the diffractive optical element 55 has an elliptical shape that is more extended in the second direction D2 than in the third direction D3. The length of the light incident on the diffractive optical element 55 in the direction of the line intersecting the diffractive optical element 55 and the surface parallel to the projection surface is 7 mm or more.

[0141] Figure 6 is a side view showing light diffracted by the diffractive optical element 55 and emitted from the emission portion 50a. Figure 6 As shown, the light diffracted by the diffractive optical element 55 is greatly expanded in the third direction D3. Thus, a projection pattern 41 extending in the first direction D1 is projected. The light diffracted by the diffractive optical element 55 is hardly expanded in the direction of the line intersecting the diffractive optical element 55 and the surface parallel to the projection surface 40 (the second direction D2 in the example shown in the figure). The light diffracted by the diffractive optical element 55 is further expanded in the third direction D3 than in the direction of the line intersecting the diffractive optical element 55 and the surface parallel to the projection surface 40. Thus, a projection pattern 41 whose length in the first direction D1 is longer than the maximum length of the length in the second direction D2 is projected.

[0142] In the third direction D3, the radiation intensity of the light diffracted by the diffractive optical element 55 is higher at a position far from the projection plane 40 than near the projection plane 40. Figure 5 and Figure 6 In the example shown, the radiation intensity of light diffracted by the diffractive optical element 55 at a position Py of the diffractive optical element 55 far from the projection plane 40 is higher than the radiation intensity of light diffracted by the diffractive optical element 55 at a position Px of the diffractive optical element 55 close to the projection plane 40 .

[0143] The radiation intensity of light refers to the energy of light contained in a unit solid angle. The radiation intensity of light is a value defined by JIS Z8000-7:2014. The radiation intensity is measured at a position far enough away from the light source, and the radiation intensity is calculated based on the distance from the light source and the measured radiation intensity. Specifically, a radiation meter is set at a distance of d[m] from the light source so that it faces the light source. If the radiation intensity measured at this time is set as E[W / m 2 ], the radiation intensity I [W / sr] is calculated as I = E × d 2 The irradiance used for calculating the radiation intensity is a value measured using an illuminance meter (“Spectroradiometer CL-500A” manufactured by Konica Minolta) in accordance with JIS C1609-1:2006.

[0144] The lighting device 50 can project a predetermined projection pattern 41 by being oriented in a predetermined direction relative to the projection plane 40. Alternatively, an alignment mark may be provided on the lighting device 50 so that the orientation relative to the projection plane 40 at which the predetermined projection pattern 41 can be projected can be easily identified. The alignment mark is, for example, a pattern or a concave-convex shape provided on the housing of the lighting device 50.

[0145] The light diffracted by the element diffractive optical element 56 expands in the second direction D2 after being emitted from the emission portion 50a. The length of the projection pattern 41 near the lighting device 50 in the second direction D2 is longer than the length (in the example shown in the figure, the length La in the second direction D2) of the intersection of the element diffractive optical element 56 and the surface parallel to the projection surface 40. The length La of the intersection of the element diffractive optical element 56 and the surface parallel to the projection surface 40 is, for example, 0.3 mm or more and 6.0 mm or less.

[0146] In the first embodiment, each element diffraction optical element 56 diffracts light so that the light diffracted by the diffraction optical element 55 as a whole narrows in the second direction D2 in the projection pattern 41. In other words, the light diffracted by the diffraction optical element 55 converges in the second direction D2. When the diffraction characteristics of each element diffraction optical element are designed to be all the same, the diffracted light will not overlap at the same position on the projection surface 40. Therefore, with respect to the projection pattern 41, the radiation intensity at the end of the pattern gradually decreases, the contrast during visual confirmation deteriorates, and it is difficult to recognize the pattern during visual confirmation. By appropriately designing the diffraction characteristics of the element diffraction optical element 56, the light diffracted by the diffraction optical element 55 as a whole can be narrowed in the second direction D2 in the projection pattern 41. The diffraction optical element 55 includes a plurality of element diffraction optical elements 56, thereby enabling the light diffracted by the diffraction optical element 55 to converge in the second direction D2. The length of the projection pattern 41 near the lighting device 50 in the second direction D2 is shorter than the maximum length (in the example shown in the figure, the maximum length Lc in the second direction) of the lengths of the light incident on the diffractive optical element 55 and the plane parallel to the projection plane 40. The maximum length Lc of the lengths of the light incident on the diffractive optical element 55 and the plane parallel to the projection plane 40 is, for example, not less than 4.0 mm and not more than 60 mm.

[0147] The length of the projection pattern 41 in the second direction D2 near the lighting device 50 refers to the minimum length Lb1 of the projection pattern 41 in the second direction D2. That is, the minimum length Lb1 of the projection pattern 41 in the second direction D2 is shorter than the maximum length Lc of the length of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection surface 40, and is longer than the length La of the element diffractive optical element 56 intersecting the surface parallel to the projection surface 40. The minimum length Lb1 of the projection pattern 41 in the second direction D2 is, for example, not less than 2.0 mm and not more than 20 mm.

[0148] Alternatively, the length of the projection pattern 41 near the lighting device 50 in the second direction D2 refers to the length Lb2 of the projection pattern 41 at the first end E1, which is the end close to the lighting device 50 in the first direction D1, in the second direction D2. That is, the length Lb2 of the projection pattern 41 at the end close to the lighting device 50 in the first direction D1 in the second direction D2 is shorter than the maximum length Lc of the length of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection surface 40, and is longer than the length La of the element diffractive optical element 56 intersecting the surface parallel to the projection surface 40. The length Lb2 of the projection pattern 41 at the first end E1, which is the end close to the lighting device 50 in the first direction D1, in the second direction D2 is, for example, not less than 2.0 mm and not more than 40 mm.

[0149] It is also possible that the length of the projection pattern 41 at the end on the side away from the lighting device 50 in the first direction D1, that is, the second end E2, in the second direction D2 is shorter than the maximum length Lc of the intersection of the light incident on the diffractive optical element 55 and the surface parallel to the projection plane 40, and is longer than the length La of the intersection of the element diffractive optical element 56 and the surface parallel to the projection plane 40.

[0150] Alternatively, the length of the projection pattern 41 in the second direction D2 near the lighting device 50 refers to the length Lb3 of the projection pattern 41 in the second direction D2 at the position where the illumination becomes maximum, that is, the maximum illumination position Pmax. That is, the length Lb3 of the projection pattern 41 in the second direction D2 at the position where the illumination becomes maximum is shorter than the maximum length Lc of the length of the light incident on the diffractive optical element 55 intersecting with the surface parallel to the projection surface 40, and is longer than the length La of the element diffractive optical element 56 intersecting with the surface parallel to the projection surface 40. The length Lb3 of the projection pattern 41 in the second direction D2 at the position where the illumination becomes maximum is, for example, not less than 2.0 mm and not more than 30 mm.

[0151] The illumination system 30 is designed so that the diffraction characteristics of the diffractive optical element 55 and the diffraction characteristics of the element diffractive optical element 56 satisfy the above conditions. That is, the diffraction characteristics of the diffractive optical element 55 are determined in the following manner: the minimum length Lb1 of the length of the projection pattern 41 in the second direction D2 is shorter than the maximum length of the length of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection surface 40. The diffraction characteristics of the element diffractive optical element are determined in such a manner that the minimum length Lb1 of the length of the projection pattern 41 in the second direction D2 is longer than the maximum length La of the length of the plurality of element diffractive optical elements 56 intersecting the surface parallel to the projection surface 40.

[0152] Alternatively, the diffraction characteristic of the diffractive optical element 55 is determined in the following manner: the length Lb2 of the projection pattern 41 at the first end E1, which is the end portion close to the lighting device 50 in the first direction D1, in the second direction D2 is shorter than the maximum length Lc of the lengths of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection surface 40. The diffraction characteristic of the element diffractive optical element 56 is determined in such a manner that the length Lb2 of the projection pattern 41 at the first end E1, which is the end portion close to the lighting device 50 in the first direction D1, in the second direction D2 is longer than the maximum length La of the lengths of the plurality of element diffractive optical elements 56 intersecting the surface parallel to the projection surface 40.

[0153] Alternatively, the diffraction characteristic of the diffractive optical element 55 is determined in the following manner: the length Lb3 of the projection pattern 41 in the second direction D2 at the position where the illumination becomes maximum is shorter than the maximum length Lc of the lengths of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection surface 40. The diffraction characteristic of the element diffractive optical element 56 is determined in such a manner that the length Lb3 of the projection pattern 41 in the second direction D2 at the position where the illumination becomes maximum is longer than the maximum length La of the lengths of the plurality of element diffractive optical elements 56 intersecting the surface parallel to the projection surface 40.

[0154] The operations of the illumination light observation system 10 and the illumination system 30 will be described.

[0155] like Figure 1 As shown in the figure, the lighting device 50 projects a projection pattern 41 onto the projection surface 40. The observer 5 can observe the projection pattern 41 projected onto the projection surface 40. The projection pattern 41 can also display various information. For example, the projection pattern 41 can also display the scheduled work area to the observer 5 who is performing the work. The operator as the observer 5 can use the projection pattern 41 when drawing a white line or an orange line in a road, a sidewalk, or a parking lot. Not limited to this example, the projection pattern 41 can also display a direction such as an arrow. According to this example, the projection pattern 41 can also display a moving path or an evacuation path.

[0156] In the case where the lighting device projects a projection pattern having a linear shape extending in one direction, it is required to narrow the width of the projection pattern. If the width of the projection pattern is narrowed, the light used to project the projection pattern is concentrated in a narrow range. The projection pattern is observed brightly. Even if there is a lot of ambient light such as sunlight, the projection pattern can be easily recognized. By narrowing the width of the projection pattern, the error in determining the center of the line shown by the projection pattern is reduced. By narrowing the width of the projection pattern, the linear shape of the projection pattern can be easily and accurately recognized.

[0157] Conventional lighting devices have lenses such as cylindrical lenses or rod lenses. Conventional lighting devices focus and diffuse light through lenses, thereby projecting a projection pattern having a linear shape. In order to narrow the width of the projection pattern projected by conventional lighting devices, it is necessary to focus the light through a lens. The light focused by the lens focuses on a certain point, but will diffuse if it is far away from the point. It is difficult to narrow the width of the entire projection pattern that extends in one direction with a sufficient length. When observing the light focused by the lens at a very close distance from the lighting device, high-intensity light will enter the eyes. For the safety of the eyes, this is not preferred. If the intensity of the light emitted by the light source is reduced in order to suppress the high-intensity light from entering the eyes, the projection pattern will become dark. As a result, it is difficult to recognize the linear shape of the projection pattern.

[0158] In the first embodiment, the length of the projection pattern 41 near the lighting device 50 in the second direction D2 is longer than the length of the intersection of the element diffractive optical element 56 and the surface parallel to the projection plane 40, and is shorter than the maximum length of the intersection of the light incident on the diffractive optical element 55 and the surface parallel to the projection plane 40. More specifically, the minimum length Lb1 of the projection pattern 41 in the second direction D2 is shorter than the maximum length Lc of the intersection of the light incident on the diffractive optical element 55 and the surface parallel to the projection plane 40, and is longer than the length La of the intersection of the element diffractive optical element 56 and the surface parallel to the projection plane 40. Alternatively, the length Lb2 of the projection pattern 41 at the end portion on one side close to the lighting device 50 in the first direction D1 in the second direction D2 is shorter than the maximum length Lc of the intersection of the light incident on the diffractive optical element 55 and the surface parallel to the projection plane 40, and is longer than the length La of the intersection of the element diffractive optical element 56 and the surface parallel to the projection plane 40. Alternatively, the length Lb3 of the projection pattern 41 at the position where the illumination becomes maximum in the second direction D2 is shorter than the maximum length Lc of the length of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection surface 40, and is longer than the length La of the element diffractive optical element 56 intersecting the surface parallel to the projection surface 40. In the projection pattern 41, the light diffracted by each element diffractive optical element 56 expands in the direction intersecting the surface parallel to the projection surface 40, and the light diffracted by the entire diffractive optical element 55 narrows in the direction intersecting the surface parallel to the projection surface 40. Since the light is diffused in each element diffractive optical element 56, it is difficult for high-intensity light to enter the eyes even if it is observed at a very close distance from the lighting device 50. Since the light diffracted by the entire diffractive optical element 55 is focused, the width of the projection pattern 41 can be narrowed. It is possible to reduce the intensity of light at a very close distance while shortening the length of the projection pattern 41 extending in the first direction D1 in the second direction D2.

[0159] The light incident on the diffractive optical element 55 is wider in the direction of the line intersecting the diffractive optical element 55 and the surface parallel to the projection surface 40 than in the third direction D3, and the light diffracted by the diffractive optical element 55 is further expanded in the third direction D3 than in the direction of the line intersecting the diffractive optical element 55 and the surface parallel to the projection surface 40. The light emitted from the lighting device 50 is expanded in two directions, the third direction D3 and the direction of the line intersecting the diffractive optical element 55 and the surface parallel to the projection surface 40. Thus, the light is spread in a planar shape. The radiation intensity of the light emitted from the emission portion 50a is reduced. The intensity of light at a very close distance can be reduced.

[0160] The length of the light incident on the diffractive optical element 55 in the direction of the line intersecting the diffractive optical element 55 and the surface parallel to the projection plane 40 is greater than 7 mm. The length of the light emitted from the lighting device 50 in the direction of the line intersecting the diffractive optical element 55 and the surface parallel to the projection plane 40 is greater than 7 mm. Even if the light from the lighting device 50 is observed at an extremely close distance, the intensity of the light observed at an extremely close distance can be reduced because the light is sufficiently diffused. According to IEC60825-1:2014, the size of the pupil of the human eye is specified to be 7 mm in diameter in a dark place. Since the length of the light emitted from the lighting device extends to more than 7 mm, damage to the eyes can be reduced even if the light from the lighting device 50 is observed at an extremely close distance.

[0161] In the third direction D3, the radiation intensity of the light diffracted by the diffractive optical element 55 is stronger at a position away from the projection plane 40 than near the projection plane 40. Among the light diffracted by the diffractive optical element 55, the light at a position away from the projection plane 40 in the third direction D3 affects the brightness of the projection pattern 41 at a position away from the lighting device 50 in the first direction D1. The radiation intensity of the light diffracted by the diffractive optical element 55 is stronger at a position away from the projection plane 40 than near the projection plane 40, thereby making the brightness of the projection pattern 41 in the first direction D1 close to uniform.

[0162] The illumination light observation system 10 includes an illumination system 30 and an observation auxiliary device 11. The observation auxiliary device 11 includes an optical filter 15. The observer 5 can wear the observation auxiliary device 11 to observe the projection pattern 41. The observer 5 wearing the observation auxiliary device 11 observes the projection pattern 41 through the optical filter 15. The average transmittance of the optical filter 15 at the wavelength of the light projected by the illumination device 50 onto the projection surface 40 is higher than the average transmittance at other wavelengths. By observing the projection pattern 41 through the optical filter 15, it is possible to maintain the brightness of the observed projection pattern 41 while suppressing the brightness of the ambient light. For example, even if there is a lot of ambient light such as sunlight, the observer 5 wearing the observation auxiliary device 11 can clearly observe the projection pattern 41.

[0163] The lighting system 30 of the first embodiment includes: a projection plane 40 parallel to the first direction D1 and the second direction D2 orthogonal to the first direction D1; and a lighting device 50 that projects a projection pattern 41 extending in the first direction D1 onto the projection plane 40. The lighting device 50 includes a light source 51 and a diffractive optical element 55 that diffracts the light from the light source 51 to form the projection pattern 41. The diffractive optical element 55 includes a plurality of element diffractive optical elements 56 that diffract the light from the light source 51. The minimum length Lb1 of the length of the projection pattern 41 in the second direction D2 is shorter than the maximum length Lc of the length of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection plane 40, and is longer than the length La of the element diffractive optical element 56 intersecting the surface parallel to the projection plane 40. Alternatively, the length Lb2 of the projection pattern 41 at the end portion on one side close to the lighting device 50 in the first direction D1 in the second direction D2 is shorter than the maximum length Lc of the lengths of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection plane 40, and is longer than the length La of the element diffractive optical element 56 intersecting the surface parallel to the projection plane 40. Alternatively, the length Lb3 of the projection pattern 41 at the position where the illumination is maximum in the second direction D2 is shorter than the maximum length Lc of the lengths of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection plane 40, and is longer than the length La of the element diffractive optical element 56 intersecting the surface parallel to the projection plane 40. In the projection pattern 41, the light diffracted by each element diffractive optical element 56 expands in the direction intersecting the surface parallel to the projection plane 40, and the light diffracted by the entire diffractive optical element 55 narrows in the direction intersecting the surface parallel to the projection plane 40. Since the light is diffused by each element of the diffractive optical element 56, it is difficult for high-intensity light to enter the eyes even when observing at a very close distance from the lighting device 50. Since the light diffracted by the entire diffractive optical element 55 is focused, the width of the projection pattern 41 can be narrowed. While reducing the intensity of light at a very close distance, the length of the projection pattern 41 extending in the first direction D1 in the second direction D2 can be shortened.

[0164] Various changes can be added to the above-mentioned embodiment.

[0165] The observer 5 may observe the projection pattern 41 projected on the projection plane 40 without wearing the observation support device 11. The observer 5 may observe the projection pattern 41 projected on the projection plane 40 without passing through the optical filter 15.

[0166] Figure 7 and Figure 8 A modification example of the lighting system 30 of the first embodiment is shown. Figure 7 FIG. 3 is a top view of a lighting system 30 according to a modified example. Figure 8This is a diagram of a diffractive optical element 55 in an emission portion 50a of a modified example as viewed from the first direction D1. In the first embodiment described above, the lighting device 50 projects the projection pattern 41 onto the projection surface 40 along the first direction D1. Figure 7 In a modified example shown, the projection pattern 41 is projected from a direction inclined relative to the first direction D1 onto the projection plane 40. By appropriately designing the diffraction characteristics of the diffractive optical element 55, the projection pattern 41 can be appropriately projected onto the projection plane 40 even from a direction inclined relative to the first direction D1.

[0167] In this variation, if Figure 8 As shown in FIG. 4 , the direction of the line where the diffractive optical element 55 intersects the surface parallel to the projection surface is inconsistent with the second direction D2. The maximum length Lc of the length where the light incident on the diffractive optical element 55 intersects the surface parallel to the projection surface 40 is inconsistent with the length of the diffractive optical element 55 along the second direction D2. The length La where the element diffractive optical element 56 intersects the surface parallel to the projection surface is inconsistent with the length of the element diffractive optical element 56 along the second direction D2.

[0168] In this modification, similarly to the first embodiment described above, the minimum length Lb1 of the projection pattern 41 in the second direction D2 is shorter than the maximum length Lc of the lengths of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection surface 40, and is longer than the length La of the element diffractive optical element 56 intersecting the surface parallel to the projection surface 40. Alternatively, the length Lb2 of the projection pattern 41 in the second direction D2 at the end portion on one side close to the lighting device 50 in the first direction D1 is shorter than the maximum length Lc of the lengths of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection surface 40, and is longer than the length La of the element diffractive optical element 56 intersecting the surface parallel to the projection surface 40. Alternatively, the length Lb3 of the projection pattern 41 in the second direction D2 at the position where the illumination is maximum is shorter than the maximum length Lc of the lengths of the light incident on the diffractive optical element 55 intersecting the surface parallel to the projection surface 40, and is longer than the length La of the element diffractive optical element 56 intersecting the surface parallel to the projection surface 40. Thus, the length of the projection pattern 41 extending in the first direction D1 in the second direction D2 can be shortened while reducing the intensity of light at an extremely close distance.

[0169] <Second Embodiment>

[0170] Fig. 9 FIG. 2 is a side view showing an illumination light imaging system according to a second embodiment. Fig. 9As shown in FIG. 1 , the illumination light imaging system 20 of the second embodiment includes an illumination system 30 and an imaging device 21. The illumination system 30 has the same configuration as that of the illumination system 30 of the first embodiment described above.

[0171] The camera device 21 captures a projection pattern 41 based on the lighting system 30. The observer 5 can observe the projection pattern 41 through the image captured by the camera device 21. The camera device 21 includes an imaging element 23 and an optical filter 25. The optical filter 25 has the same structure as the optical filter 15 of the first embodiment described above. The camera device 21 captures the light incident on the imaging element 23. The camera device 21 is configured to allow the light that has passed through the optical filter 25 to be incident on the imaging element 23. The camera device 21 captures the light that has passed through the optical filter 25. The observer 5 can observe the projection pattern 41 through the image obtained by capturing the light that has passed through the optical filter 25. For example, even if there is a lot of ambient light such as sunlight, the observer 5 can clearly observe the projection pattern 41.

[0172] The imaging device 21 may not include the optical filter 25 . The observer 5 may observe the projection pattern 41 through the image captured without passing through the optical filter 25 .

[0173] like Fig. 9 As shown, the illumination light imaging system 20 further includes a display device 27. The display device 27 is connected to the imaging device 21. The display device 27 displays the image captured by the imaging device 21. The observer 5 can also observe the image of the projection pattern 41 displayed by the display device 27.

[0174] Fig.10 An example of an image displayed by the display device 27 is shown. Fig.10 In the example shown, the display device 27 displays a portion of the projection pattern 41. Fig.10 In the example shown, a portion of the projection pattern 41 extending in the first direction D1 is difficult to be observed due to ambient light, etc. By processing the image captured by the camera device 21 by an image processing device (not shown), the unobserved portion of the projection pattern 41 can be predicted and supplemented based on the observed portion of the projection pattern 41. The display device 27 can also display an image supplemented with the unobserved portion of the projection pattern 41.

[0175] The imaging device 21 and the display device 27 may be movable. The imaging device 21 and the display device 27 may also be applied to a moving object such as a vehicle, a ship, an airplane, or a train.

[0176] <Third Embodiment>

[0177] Fig.113 is a perspective view showing a lighting device 50 of the third embodiment. The lighting device 50 of the third embodiment can be replaced by the lighting device 50 of the first and second embodiments. The lighting system 30 of the first and second embodiments may also include the lighting device 50 of the third embodiment instead of the lighting device 50 of each embodiment.

[0178] In the lighting system 30 including the lighting device 50 of the third embodiment, the projection pattern 41 projected onto the projection plane 40 has a linear shape with the first direction D1 as the longitudinal direction. The length of the projection pattern 41 in the first direction D1 is, for example, 0.1 m to 100 m.

[0179] like Fig.11 As shown in the figure, the lighting device 50 of the third embodiment includes a light source 51, a shaping optical system 53, and an optical element 57. The light source 51 and the shaping optical system 53 are the same structures as the light source 51 and the shaping optical system 53 of the first embodiment. The optical element 57 acts on the light from the light source 51. The optical element 57 includes a first lens 58 and a second lens 59. In the lighting device 50, the light shaped by the shaping optical system 53 is emitted from the emission portion 50a through the first lens 58 and the second lens 59.

[0180] The first lens 58 focuses the incident light in the second direction D2. The first lens 58 is, for example, a convex lens curved in the second direction D2. The focal length of the first lens 58 is longer than the length of the projection pattern 41 in the first direction D1. Thus, the light transmitted through the first lens 58 does not diffuse in the projection pattern 41 even if it is far away from the lighting device 50, but is narrowed in the second direction D2 in almost the entire projection pattern 41.

[0181] The second lens 59 diffuses incident light in the third direction D3. The second lens 59 is, for example, a concave lens curved in the third direction D3. The light transmitted through the second lens spreads in the third direction D3, and a projection pattern 41 extending in the first direction D1 can be formed.

[0182] Fig.12 This is a diagram of the optical element 57 in the emission section 50a as viewed from the first direction D1. Fig.12 The oblique line portion of represents the portion where light is incident on the optical element 57. The light transmitted through the optical element 57 is narrowed in the second direction D2 in the substantially entire projection pattern 41 by the first lens 58. The minimum length Lb1 of the projection pattern in the second direction D2 is shorter than the maximum length of the length of the light incident on the optical element 57 intersecting the surface parallel to the projection surface 40 (in the example shown in the figure, the maximum length Lc of the length in the second direction D2).

[0183] The lighting system 30 is designed so that the optical characteristics of the optical element 57 satisfy the above conditions. That is, the optical characteristics of the optical element 57 are determined in such a way that the minimum length Lb1 of the length of the projection pattern 41 in the second direction D2 is shorter than the maximum length Lc of the length of the intersection of the light incident on the optical element 57 and the surface parallel to the projection surface 40.

[0184] Since the light is expanded in the third direction D3 by the second lens 59, it is difficult for high-intensity light to enter the eyes even when observing at an extremely close distance from the lighting device 50. By focusing the incident light in the second direction D2 by the first lens 58, the width of the projection pattern 41 can be narrowed. The length of the projection pattern 41 extending in the first direction D1 in the second direction D2 can be shortened while reducing the intensity of light at an extremely close distance.

[0185] The respective embodiments and their modifications may be combined as appropriate.

[0186] Description of symbols

[0187] 5: Observer;

[0188] 10: Illumination light observation system;

[0189] 11: Observation aids;

[0190] 15: Optical filter;

[0191] 20: Illumination light camera system;

[0192] 21: Camera device;

[0193] 25: optical filter;

[0194] 30: Lighting system;

[0195] 40: projection surface;

[0196] 41: Projection pattern;

[0197] 50: Lighting device;

[0198] 51: light source;

[0199] 53: Plastic optical system;

[0200] 55: Diffractive optical element;

[0201] 56: element diffractive optical element;

[0202] 57: Optical components;

[0203] 58: 1st lens;

[0204] 59: The second lens.

Claims

1. A lighting system, in, The lighting system comprises: a projection plane parallel to the first direction and a second direction orthogonal to the first direction; and an illumination device that projects a projection pattern extending in the first direction onto the projection surface, The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern. The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source. The minimum length of the projection pattern in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface.

2. A lighting system, in, The lighting system comprises: a projection plane parallel to the first direction and a second direction orthogonal to the first direction; and an illumination device that projects a projection pattern extending in the first direction onto the projection surface, The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern. The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source. The length of the projection pattern at the end portion on one side close to the lighting device in the first direction in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface.

3. A lighting system, in, The lighting system comprises: a projection plane parallel to the first direction and a second direction orthogonal to the first direction; and an illumination device that projects a projection pattern extending in the first direction onto the projection surface, The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern. The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source. The length of the projection pattern in the second direction at the position where the illumination is maximum is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface.

4. The lighting system according to any one of claims 1 to 3, in, The light incident on the diffractive optical element is wider in the direction of a line where the diffractive optical element intersects a surface parallel to the projection surface than in a third direction which is not parallel to the projection surface. The light diffracted by the diffractive optical element spreads in the third direction more than the direction of a line intersecting the diffractive optical element and a surface parallel to the projection surface.

5. The lighting system according to any one of claims 1 to 3, in, The length of the light incident on the diffractive optical element in the direction of the line where the diffractive optical element intersects with a plane parallel to the projection plane is 7 mm or more.

6. The illumination system according to any one of claims 1 to 3, wherein, in a third direction not parallel to the projection plane, the emission intensity of the light diffracted by the diffractive optical element is stronger at a position away from the projection plane than near the projection plane.

7. An illumination system, wherein, the illumination system includes: a projection plane parallel to a first direction and a second direction orthogonal to the first direction; and an illumination device that projects a projection pattern extending in the first direction onto the projection plane, the illumination device having: a light source; and an optical element that acts on the light from the light source to form the projection pattern, the minimum length of the projection pattern in the second direction is shorter than the maximum length of the length where the light incident on the optical element intersects with a plane parallel to the projection plane.

8. An illumination light observation system, wherein, the illumination light observation system includes: the illumination system according to any one of claims 1 to 3, 7; and an optical filter having a higher average transmittance at the wavelength of the light projected by the illumination device onto the projection plane than at other wavelengths.

9. An illumination light imaging system, wherein, the illumination light imaging system includes: the illumination system according to any one of claims 1 to 3, 7; and an imaging device that captures the projection pattern.

10. The illumination light imaging system according to claim 9, wherein, the imaging device has an optical filter having a higher average transmittance at the wavelength of the light projected by the illumination device onto the projection plane than at other wavelengths.

11. An illumination device that projects a projection pattern extending in the first direction onto a projection plane parallel to a first direction and a second direction orthogonal to the first direction, wherein, the illumination device has: a light source; and a diffractive optical element that diffracts the light from the light source to form the projection pattern, the diffractive optical element includes a plurality of element diffractive optical elements that respectively diffract the light from the light source, the minimum length of the projection pattern in the second direction is shorter than the maximum length of the length where the light incident on the diffractive optical element intersects with a plane parallel to the projection plane, and is longer than the maximum length of the length where the element diffractive optical element intersects with a plane parallel to the projection plane.

12. An illumination device that projects a projection pattern extending in the first direction onto a projection plane parallel to a first direction and a second direction orthogonal to the first direction, wherein, the illumination device has: a light source; and a diffractive optical element that diffracts the light from the light source to form the projection pattern, the diffractive optical element includes a plurality of element diffractive optical elements that respectively diffract the light from the light source, The length of the projection pattern at the end portion on one side close to the lighting device in the first direction in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface.

13. A lighting device that projects a projection pattern extending in a first direction onto a projection plane parallel to a first direction and a second direction orthogonal to the first direction, in, The lighting device comprises: a light source; and a diffractive optical element which diffracts light from the light source to form the projection pattern. The diffractive optical element includes a plurality of diffractive optical elements that diffract the light from the light source. The length of the projection pattern in the second direction at the position where the illumination is maximum is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface, and is longer than the maximum length of the intersection of the element diffractive optical element and the surface parallel to the projection surface.

14. A lighting device that projects a projection pattern extending in a first direction onto a projection plane parallel to a first direction and a second direction orthogonal to the first direction, in, The lighting device comprises: a light source; and an optical element, which acts on the light from the light source to form the projection pattern. The minimum length of the projection pattern in the second direction is shorter than the maximum length of the length of light incident on the optical element intersecting the surface parallel to the projection surface.

15. A method for designing an illumination system, wherein the illumination system projects a projection pattern extending in a first direction onto a projection plane parallel to the first direction and in a second direction orthogonal to the first direction by means of an illumination device including a diffractive optical element, in, The design method of the lighting system comprises the following steps: The diffraction characteristic of the diffractive optical element is determined in such a manner that the minimum length of the projection pattern in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface; as well as The diffraction characteristics of the element diffractive optical element are determined in such a way that the minimum length of the projection pattern in the second direction is longer than the maximum length of the intersection of multiple element diffractive optical elements included in the diffractive optical element and the surface parallel to the projection surface.

16. A method for designing an illumination system, wherein the illumination system projects a projection pattern extending in a first direction onto a projection plane parallel to a first direction and in a second direction orthogonal to the first direction by means of an illumination device including a diffractive optical element, in, The design method of the lighting system comprises the following steps: The diffraction characteristic of the diffractive optical element is determined in such a manner that the length of the projection pattern at the end portion on one side close to the lighting device in the first direction in the second direction is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface; as well as The diffraction characteristics of the elemental diffractive optical element are determined in such a manner that the length of the projection pattern at the end portion of the side close to the lighting device in the first direction in the second direction is longer than the maximum length of the intersection of multiple elemental diffractive optical elements included in the diffractive optical element and the surface parallel to the projection surface.

17. A method for designing an illumination system, wherein the illumination system projects a projection pattern extending in a first direction onto a projection plane parallel to a first direction and in a second direction orthogonal to the first direction by means of an illumination device including a diffractive optical element, in, The design method of the lighting system comprises the following steps: The diffraction characteristic of the diffractive optical element is determined in such a manner that the length of the projection pattern in the second direction at the position where the illumination is maximum is shorter than the maximum length of the intersection of the light incident on the diffractive optical element and the surface parallel to the projection surface; as well as The diffraction characteristics of the element diffractive optical element are determined in such a way that the length of the projection pattern in the second direction at the position where the illumination is maximum is longer than the maximum length of the intersection of multiple element diffractive optical elements included in the diffractive optical element and the surface parallel to the projection surface.

18. A method for designing an illumination system, wherein the illumination system projects a projection pattern extending in a first direction onto a projection surface parallel to a first direction and a second direction orthogonal to the first direction by means of an illumination device including an optical element, in, The design method of the lighting system includes the following steps: determining the optical characteristics of the optical element in such a way that the minimum length of the projection pattern in the second direction is shorter than the maximum length of the intersection of the light incident on the optical element and the surface parallel to the projection surface.

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