Optical system device and optical element manufacturing method

Abstract

The present invention aims to provide an optical system device that does not require a collimating lens and can utilize light with high efficiency. The optical system device comprises: a light source unit (1) that irradiates light with a wavelength of λ; and an optical element (2) that has a concave-convex structure composed of periodic lenses, wherein n is a natural number greater than or equal to 1, and the size of the pitch of the concave-convex structure from the smallest to the kth (k is a natural number greater than or equal to 1) pitch is set to P k When any one or more spacings P k , the distance L1 between the light source and the optical element is designed to satisfy Formula 1, where: #imgabs0#

Description

Technical Field

[0001] The invention relates to an optical system device and an optical element manufacturing method. Background Art

[0002] Three-dimensional measurement sensors using the time-of-flight (TOF) method are used in portable devices, cars, robots, etc. It measures the distance of an object based on the time it takes for light from a light source to be reflected and returned. As long as the light from the light source is evenly irradiated to a specified area of ​​the object, the distance at each irradiated point can be measured, and the three-dimensional structure of the object can be detected.

[0003] The sensor system includes a light irradiation unit that irradiates light to an object, a camera unit that detects light reflected from various points of the object, and a calculation unit that calculates the distance of the object based on a signal received by the camera.

[0004] The camera unit and the computing unit can use existing CMOS imagers and CPUs, so the unique part of the above system is the light irradiation unit including lasers and filters. In particular, the diffusion filter that shapes the laser beam by transmitting the laser beam through the microlens array and uniformly irradiates the object in the controlled area is a characteristic component of the above system.

[0005] Here, the microlens array of the conventional diffusion filter has a periodic structure, so there is a problem of uneven light intensity due to the influence of diffraction. Therefore, in order to suppress this unevenness, it is considered to randomly arrange each lens (for example, Patent Document 1).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application No. 2006-500621 Summary of the invention

[0009] On the other hand, TOF has the need for long-distance measurement, and in terms of the intensity of the irradiated light, long-distance measurement requires the highest possible intensity. However, since the uniformity of the irradiated light of the randomly configured microlens array is high, the corresponding light intensity will be reduced, so it is not suitable for long-distance measurement.

[0010] Therefore, as a method of saving power and being able to process relatively strong light signals, a method of irradiating a dot pattern (Dot Pattern) and performing three-dimensional measurement based on the flight time of the light has been studied.

[0011] As a filter for converting such an incident laser beam into a dot pattern, a diffractive optical element (DOE) formed by a dielectric concave-convex pattern and causing the phase difference of light to change according to the position of the transmission surface is widely used. In addition, as a laser beam source, a vertical cavity surface emitting laser (VCSEL) that can easily make a two-dimensional array is often used.

[0012] The light emitted from the VCSEL is first converted into parallel light by a collimating lens. The DOE changes the phase difference by transmitting the collimated light through the concave-convex pattern, and gives a predetermined directional distribution by diffraction of the light. As a result, the light is irradiated onto the surface of the irradiated object with a predetermined intensity distribution.

[0013] Here, the light emitted by the VCSEL has a divergence angle of about 20 degrees. When used in a dot projector, a collimating lens is required as described above. However, in order to generate collimated light, the collimating lens needs to place the light source at the focal position of the lens. In order to obtain high-quality collimated light, there is a problem that the focal distance is long and the device size is large.

[0014] Therefore, an object of the present invention is to provide an optical system device which does not require a collimating lens and has a high efficiency in utilizing light, and a method for manufacturing an optical element used in the device.

[0015] In order to achieve the above-mentioned object, the optical system device of the present invention is characterized in that it includes: an optical element, which is obtained by periodically arranging lenses that transmit light with a wavelength of λ; and an irradiation unit, which has a light source that irradiates light with a wavelength of λ to a plurality of lenses among the lenses, wherein n is set to a natural number greater than 1, and the size of the pitch of the lenses from the smallest to the kth (k is a natural number greater than 1) is set to P k When any one or more spacings P k , the distance L1 between the irradiation part and the optical element satisfies the following formula 1:

[0016] (Number 1)

[0017]

[0018] In this case, the lens is preferably an aspherical lens having a repetition rate of 10% or less in the normal direction of the surface.

[0019] In addition, it is also possible to have a porous baffle having an opening for shielding a part of the light. The porous baffle may have an opening at least in a portion including the optical axis of the lens. In addition, the porous baffle may be arranged in the optical path of the noise light of the lens. The porous baffle may also be arranged at the boundary portion of the lens. In addition, it is also possible to have a porous baffle that shields the light irradiated to the boundary portion of the lens.

[0020] In addition, the porous barrier plate and the optical element may be formed integrally.

[0021] Furthermore, the optical element may include a light diffusion portion formed at a boundary portion of the lens, the light diffusion portion refracting the transmitted light to the outside of an irradiation angle of the lens.

[0022] Additionally, the shape of the lens can be rotationally asymmetric.

[0023] In addition, it is preferable that the above-mentioned formula 1 is satisfied for the smallest pitch P1, and it is further preferable that the above-mentioned formula 1 is satisfied for the second smallest pitch P2.

[0024] Furthermore, a reflecting mirror for reflecting the light from the irradiating unit may be provided in order to adjust the distance L1.

[0025] Furthermore, the optical system device of the present invention may include a plurality of the irradiation units.

[0026] In addition, the irradiation unit may include: a first irradiation unit, which is obtained by regularly arranging a plurality of light sources that irradiate light with a wavelength of λ; and a second irradiation unit, which is obtained by regularly arranging a plurality of light sources that irradiate light with a wavelength of λ in a manner that is staggered half a period in the longitudinal and transverse directions with the light sources of the first irradiation unit.

[0027] Alternatively, the irradiation unit may include a first irradiation unit, a second irradiation unit, and a third irradiation unit formed by regularly arranging a plurality of light sources irradiating light of wavelength λ, and the lens of the optical element may be spaced at a pitch P. k In the direction, the light sources of the first irradiation unit, the second irradiation unit and the third irradiation unit are staggered by P k / 3 arrangement.

[0028] In this case, the irradiation units may emit light in sequence with time staggered.

[0029] In addition, the planar shape of the lens may be a square or rectangle with a length of R on one side, and regarding the arrangement of the lenses, when i is a natural number greater than 1, columns of lenses continuous in the direction of the side are arranged so as to be staggered by R / i.

[0030] More preferably, the irradiation unit includes a VCSEL having a plurality of light emission modes, and among the light emission modes, a mode having a maximum intensity at the center of the optical axis accounts for 40% or more of the entire mode.

[0031] In addition, when m is a natural number greater than or equal to 1, the irradiation section is obtained by regularly arranging a plurality of light sources in any period direction of the lens of the optical element at m times or 1 / m times the period.

[0032] Alternatively, the irradiation unit may be formed by arranging the light sources in a hexagonal pattern with a pitch of mP1 or P1 / m, and the plane shape of the lens of the optical element may be such that the ratio of the short side to the long side is rectangle.

[0033] In addition, the optical system device of the present invention may also include: a diffuser, which diffuses the light of the irradiation part into a specified shape; a half-mirror, which is arranged between the light source and the diffuser, so that a part of the light of the irradiation part is transmitted and a part is reflected; and a reflecting mirror, which reflects the light reflected by the half-mirror toward the optical element.

[0034] In addition, the optical system device of the present invention may include a diffuser irradiation unit obtained by arranging a plurality of light sources irradiating light of wavelength λ in the same manner as the irradiation unit, and a distance L2 between the diffuser irradiation unit and the optical element satisfies the following formula 2:

[0035] (Number 2)

[0036]

[0037] In addition, the optical system device of the present invention may also have a diffuser irradiation unit obtained by arranging a plurality of light sources that irradiate light with a wavelength of λ, and when m is a natural number greater than 1, the diffuser irradiation unit is obtained by arranging the plurality of light sources in a periodic direction of the lens of the optical element in a manner that does not become m times or 1 / m times the period.

[0038] Furthermore, the optical system device of the present invention may include a diffuser irradiation section arranged in the same regular pattern as the light sources of the irradiation section, and the irradiation section and the diffuser irradiation section may have different rotation angles.

[0039] In addition, the optical element manufacturing method of the present invention is used to form an optical element obtained by periodically arranging lenses that transmit light with a wavelength of λ. The optical element manufacturing method is characterized in that it includes: a porous baffle forming step, forming a porous baffle on a substrate for shielding a portion of the light transmitted through the lens; and a lens forming step, forming the lens on the substrate on which the porous baffle is formed.

[0040] In this case, in the lens forming step, the lens may be formed so that the porous mask is arranged in the optical path of the noise light of the lens. For example, in the lens forming step, the lens is formed so that the boundary of the lens is arranged in the shielding portion of the porous mask.

[0041] In addition, in the optical element manufacturing method of the present invention, an optical element is obtained by periodically arranging lenses that transmit light with a wavelength of λ. The optical element manufacturing method is characterized in that it includes: a porous baffle forming step, coating the lenses with a shading material that prevents the light from being transmitted, and removing the shading material in a manner that a portion of the shading material remains at a position corresponding to the boundary of the lens.

[0042] Effects of the Invention

[0043] The optical system device of the present invention does not require a collimator lens and can irradiate light with high efficiency of available light. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic cross-sectional view showing the optical system device of the present invention.

[0045] Figure 2 It is a graph showing the far-field light intensity of each emission mode.

[0046] Figure 3 This is a diagram showing the far-field light intensity of each classified and synthesized emission mode.

[0047] Figure 4 This is a diagram showing the far-field light intensity of the synthesized light when the ratio of each light emission mode is changed.

[0048] Figure 5 It is a schematic plan view showing an optical element according to the present invention.

[0049] Figure 6 It is a diagram for explaining simulation 1.

[0050] Figure 7 It is a graph showing the far-field light intensity of simulation 1 (30 to 150 μm).

[0051] Figure 8 It is a graph showing the far-field light intensity of simulation 1 (159.57 to 270 μm).

[0052] Fig. 9 It is a graph showing the far-field light intensity of simulation 1 (280 to 400 μm).

[0053] Fig.10 It is a graph showing the far-field light intensity of simulation 1 (96.38 to 110.38 μm).

[0054] Fig.11 It is a graph showing the far-field light intensity of simulation 1 (111.38 to 116.38 μm).

[0055] Fig.12 This is a diagram showing the far-field light intensity of simulation 1 (202.77 to 216.77 μm).

[0056] Fig.13 This is a diagram showing the far-field light intensity of simulation 1 (217.77 to 222.77 μm).

[0057] Fig.14 It is a graph showing the far-field light intensity of simulation 1 (309.15 to 323.15 μm).

[0058] Fig.15 It is a graph showing the far-field light intensity of simulation 1 (324.15 to 329.15 μm).

[0059] Fig.16 This is a diagram for explaining Simulation 2.

[0060] Fig.17 3 is a graph showing the far-field light intensity of Simulation 2.

[0061] Fig.18 It is a diagram showing the arrangement of light sources and light distribution characteristics of Simulation 3.

[0062] Fig.19 It is a diagram showing the optical element of Simulation 3.

[0063] Fig. 20 It is a graph showing the far-field light intensity of simulation 3 (n=1).

[0064] Fig.21 It is a graph showing the far-field light intensity of simulation 3 (n=2).

[0065] Fig. 22 It is a graph showing the far-field light intensity of simulation 3 (n=3).

[0066] Fig.23 3 is a graph showing the far-field light intensity of the comparative example of Simulation 3.

[0067] Fig.24 It is a diagram showing the arrangement of light sources and light distribution characteristics of Simulation 4.

[0068] Fig.25 3 is a diagram showing an optical element of Simulation 4.

[0069] Fig.26 It is a graph showing the far-field light intensity of Simulation 4 (n=1).

[0070] Fig. 27It is a graph showing the far-field light intensity of Simulation 4 (n=2).

[0071] Fig.28 It is a graph showing the far-field light intensity of Simulation 4 (n=3).

[0072] Fig.29 3 is a diagram showing the far-field light intensity of the comparative example of Simulation 4.

[0073] Fig.30 It is a graph showing the far-field light intensity of simulation 5 (with an inflection point).

[0074] Fig.31 It is a graph showing the far-field light intensity of simulation 5 (no inflection point).

[0075] Fig.32 This is a diagram for explaining a method for measuring the normal line repetition rate.

[0076] Fig.33 It is a graph showing the far-field light intensity of Simulation 6 (Model 1).

[0077] Fig.34 It is a graph showing the far-field light intensity of Simulation 6 (Model 2).

[0078] Fig.35 It is a graph showing the far-field light intensity of Simulation 6 (Model 3).

[0079] Fig.36 It is a graph showing the far-field light intensity of Simulation 6 (Model 4).

[0080] Fig.37 It is a graph showing the far-field light intensity of Simulation 6 (Model 5).

[0081] Fig.38 It is a graph showing the far-field light intensity of Simulation 6 (Model 6).

[0082] Fig.39 It is a figure which shows the porous mask concerning this invention.

[0083] Fig.40 Graph showing the far-field light intensity of Simulation 7 (with a multi-aperture baffle).

[0084] Fig.41 Graph showing the far-field light intensity of Simulation 7 (without a porous baffle).

[0085] Fig.42 It is a graph showing the far-field light intensity of Simulation 8 (Model 1).

[0086] Fig.43 It is a graph showing the far-field light intensity of Simulation 8 (Model 2).

[0087] Fig.44It is a graph showing the far-field light intensity of Simulation 8 (Model 3).

[0088] Fig.45 It is a graph showing the far-field light intensity of Simulation 8 (Model 4).

[0089] Fig.46 This is a diagram showing a light diffusion portion according to the present invention.

[0090] Fig.47 3 is a diagram showing the far-field light intensity of Simulation 9.

[0091] Fig.48 It is a figure which shows the optical element manufacturing method of this invention.

[0092] Fig.49 It is a diagram showing another method for manufacturing an optical element according to the present invention.

[0093] Fig.50 It is a diagram showing another method for manufacturing an optical element according to the present invention.

[0094] Fig.51 It is a schematic plan view showing the positional relationship between the irradiation unit and the optical element according to the present invention.

[0095] Fig.52 It is a schematic cross-sectional view showing another optical system device of the present invention.

[0096] Fig.53 It is a schematic plan view showing the principle of another optical system device according to the present invention.

[0097] Fig.54 This is a schematic cross-sectional view showing an optical system device using two types of irradiation units of the present invention.

[0098] Fig.55 It is a schematic plan view showing the principle of another optical system device according to the present invention.

[0099] Fig.56 It is a schematic cross-sectional view showing an optical system device using three types of irradiation units of the present invention.

[0100] Fig.57 This is a diagram for explaining the relationship between the arrangement of optical elements and the number of points (1x) according to the present invention.

[0101] Fig.58 This is a diagram for explaining the relationship between the arrangement of optical elements and the number of points (double) according to the present invention.

[0102] Fig.59 This is a diagram for explaining the relationship between the arrangement of optical elements and the number of points (3 times) according to the present invention.

[0103] Fig.60This is a schematic cross-sectional view showing an optical system device of the present invention that also uses a diffuser.

[0104] Fig.61 This is a schematic cross-sectional view showing an optical system device of the present invention having a dot pattern irradiation function and a diffuser function.

[0105] Fig.62 It is a schematic plan view showing the positional relationship between the irradiation unit and the optical element according to the present invention.

[0106] Fig.63 This is a diagram showing the deviation of the light source position due to the difference in the angle θ (0 to 7°) between the irradiation unit and the optical element.

[0107] Fig.64 This is a diagram showing the deviation of the light source position due to the difference in the angle θ (8 to 15°) between the irradiation unit and the optical element.

[0108] Fig.65 This is a diagram showing the deviation of the light source position caused by the difference in the angle θ (90°) between the irradiation unit and the optical element.

[0109] Fig.66 Graph showing the far-field light intensity of simulation 10 (θ=0°).

[0110] Fig.67 3 is a diagram showing the far-field light intensity of Simulation 10 (θ=1°).

[0111] Fig.68 It is a graph showing the far-field light intensity of simulation 10 (θ=5°).

[0112] Fig.69 It is a graph showing the far-field light intensity of simulation 10 (θ=10°).

[0113] Fig.70 It is a graph showing the far-field light intensity of simulation 10 (θ=15°).

[0114] Description of Reference Numerals

[0115] 1Irradiation part

[0116] 1A 1st irradiation part

[0117] 1B Second irradiation section

[0118] 2 Optical components

[0119] 3 Reflector

[0120] 4 Half mirror

[0121] 5 Diffuser-type optical elements

[0122] 6 Diffuser irradiation unit

[0123] 7. Perforated baffle

[0124] 8 Light diffusion part

[0125] 10 Light Source

[0126] 11 Irradiation Department

[0127] 12 Irradiation Department

[0128] 13 Irradiation Department

[0129] 21 Lens

[0130] 25 substrate

[0131] 60 Light Source

[0132] 70 Opening DETAILED DESCRIPTION

[0133] The optical system device of the present invention is described below. Figure 1 As shown, the optical system device of the present invention mainly includes: an irradiation unit 1 that irradiates light with a wavelength of λ; and an optical element 2 that has a periodic lens 21 .

[0134] The irradiation unit 1 can be any device as long as it irradiates light with a wavelength of λ. In addition, the irradiation unit 1 can be either a single light source or a plurality of light sources. In addition, the light of a single light source can be passed through an aperture (aperture) formed with a plurality of pores, thereby forming a plurality of light sources. In the case where the irradiation unit is composed of a plurality of light sources, it is preferred that the light sources are formed on the same plane. As a specific example of the irradiation unit 1, for example, a VCSEL (Vertical Cavity Surface Emitting LaSER) can be listed, which can be expected to have a high output with less power. The VCSEL has a plurality of light sources 10 that can irradiate light in a direction perpendicular to the light emitting surface.

[0135] (Luminous Mode)

[0136] It is also known that when the light intensity of a VCSEL is increased, the light of the VCSEL includes a plurality of emission modes such as a single mode or a multi-mode. Figure 2 Specific examples of light emission patterns are shown. Figure 2 The rotationally symmetric light emission modes (2) and (3), (4) and (6), (7) and (9), (8) and (10) shown in the figure must exist in the same ratio. Therefore, if these similar modes are synthesized separately, they can be Figure 3 As shown, they are combined into 6 types: A, B, C, D, E, and F.

[0137] If these 6 patterns are combined in the same ratio (A:B:C:D:E:F=1:1:1:1:1:1), it becomes Figure 4 As shown in (a), the maximum intensity is 0.0271. In addition, the figure shows the far-field light intensity at each light distribution angle when the power of the light source is set to 1.

[0138] On the other hand, if these six modes are combined in such a way that only one of them is twice as large as the other modes, then Figure 4 As shown in (b), when A:B:C:D:E:F=2:1:1:1:1:1, the maximum intensity is 0.03, when A:B:C:D:E:F=1:1:1:2:1:1, the maximum intensity is 0.0389, and when A:B:C:D:E:F=1:1:1:1:1:2, the maximum intensity is 0.0285. That is, if the ratio of mode A or D whose maximum intensity is located at the center of the optical axis, or mode F whose maximum intensity is close to the center of the optical axis, is increased, the maximum intensity of the synthesized light increases compared to the case where the six modes are set to the same ratio. Figure 4 (c) is the result of synthesizing only the modes A, D, and F among the six modes by five times the other modes. When A:B:C:D:E:F=5:1:1:1:1:1, the maximum intensity is 0.0354, when A:B:C:D:E:F=1:1:1:5:1:1, the maximum intensity is 0.0608, and when A:B:C:D:E:F=1:1:1:1:1:5, the maximum intensity is 0.0343. That is, the maximum intensity of the synthesized light (A:B:C:D:E:F=1:1:1:5:1:1) by five times the mode D is significantly increased.

[0139] Based on the above, when a VCSEL having multiple light emission modes is used, it is preferred that the larger the proportion of the light emission mode having the maximum intensity at the center of the optical axis in the light emission mode of the VCSEL light source, the greater the light intensity of the generated point and the greater the contrast. Therefore, it is preferred that the proportion of the mode having the maximum intensity at the center of the optical axis in the light emission mode of the light source is 40% or more, preferably 45% or more, and more preferably 60% or more. The light emission mode can be adjusted by a conventionally known method such as controlling the current injection path of the light emitting layer of the VCSEL.

[0140] The optical element 2 is obtained by periodically arranging lenses 21 that transmit light of a wavelength λ. The shape of the lens 21 can be freely designed according to the pattern of the larger point to be irradiated (hereinafter referred to as the dot pattern). For example, in the case where the dot pattern is to be circular, the shape of the lens 21 can be rotationally symmetric like a spherical lens. In addition, in the case where the dot pattern is to be non-circular, the shape of the lens 21 can be appropriately adjusted by making it non-rotationally symmetric like an aspherical lens. As a specific lens shape, for example, in addition to a convex lens or a concave lens, there is also a saddle lens that can be seen as a convex lens or a concave lens based on the cross section. In addition, in the periodic arrangement, Figure 5 In the top view shown in (a), the square or rectangular lenses 21 are arranged in a square. Figure 5 In the plan view shown in (b), the hexagonal lenses 21 are arranged hexagonally, etc.

[0141] (Distance between irradiation part and optical element)

[0142] When the wavelength of light incident from the irradiation unit 1 is λ, the pitch of the lenses 21 of the optical element 2 is P, and the distance between the irradiation unit 1 and the optical element 2 is L0, the distance L0 greatly intensifies the light in the case of the following formula A.

[0143] (Number 3)

[0144]

[0145] In addition, in this specification, the distance between the irradiation unit 1 and the optical element 2 refers to the distance from the light emitting surface of the light source of the irradiation unit to the surface of the lens 21 of the optical element on the side close to the light source. In fact, although errors caused by the size of the lens 21 will occur, the distance between the irradiation unit 1 and the lens 21 of the optical element 2 is much larger than the size of the lens 21 in the vertical direction (optical axis direction), so even if defined in this way, it has sufficient accuracy.

[0146] In addition, as shown in the following formula B, it is known that the light is greatly enhanced when the distance L between the irradiation unit 1 and the optical element 2 is n times the distance L0 (n is a natural number greater than 1). Furthermore, it is known that the light is further greatly enhanced when n is an even number.

[0147] (Number 4)

[0148]

[0149] Furthermore, the error of the distance L between the irradiation unit 1 and the optical element 2 is within 10% of L0, preferably within 5%, and more preferably within 3%. If the error of the distance L is within 10% of L0, it can be expressed as the following formula C.

[0150] (number 5)

[0151]

[0152] In addition, there may be a plurality of periods in the lens 21. For example, Figure 5 As shown in (a), when the square lenses 21 are arranged in a square in the top view, in addition to the spacing P1 between adjacent lenses, there is also a spacing in the diagonal direction. or Spacing In addition, Figure 5 As shown in (b), when the regular hexagonal lenses 21 are arranged in a hexagonal pattern in a top view, in addition to the pitch P1 between adjacent lenses, there is also a pitch In addition, as in the case where the rectangular lenses are regularly arranged in the top view, there is also a case where the lenses 21 have a plurality of different periods. In this case, the size of the pitch of the lenses 21 from the smallest to the kth (k is a natural number greater than 1) is set to P k When any one or more spacings P k , the distance L1 between the irradiation part 1 and the optical element 2 only needs to satisfy the following formula 1.

[0153] (number 6)

[0154]

[0155] In addition, it is preferred that for any two or more pitches P k , the distance L between the irradiation unit 1 and the optical element 2 is adjusted to satisfy equation 1. In this case, the smallest pitch has the greatest influence on diffraction, so it is preferred that equation 1 is satisfied for the smallest pitch P1, and it is more preferred that equation 1 is also satisfied for the second smallest pitch P2.

[0156] In addition, since diffraction is difficult to produce when the spacing P is too small compared to the wavelength λ of the light from the light source 10, within the limit of the lens 21 sufficient to produce diffraction included in the light distribution angle of the light source 10, the spacing P can be sufficiently large compared to the wavelength λ of the light from the light source 10, for example, more than 5 times, preferably more than 10 times.

[0157] Next, simulations were performed on light intensity distribution and the like in the far field when the distance L between the irradiation unit 1 and the optical element 2 was variously changed.

[0158] (Simulation 1)

[0159] The irradiation portion 1 is a wavelength of 940 nm and is Figure 6 (a) is a single light source of light with Gaussian light distribution as shown in FIG. Figure 6(b) shows a device in which slit-shaped openings are arranged at a pitch of 10 μm. In addition, the portion of the optical element other than the slit is made of a material that completely absorbs light. In addition, the distance L between the irradiation portion 1 and the optical element 2 is 38 types of changes of 10 μm each from 30 μm to 400 μm, and when n in formula A is 1 to 6, 53.19 μm (n=1), 106.38 μm (n=2), 159.67 μm (n=3), 212.77 μm (n=4), 265.96 μm (n=5), and 319.15 μm (n=6). Figure 7 to Figure 9 The simulation results obtained using the optical simulation software BeamPROP (manufactured by Synopsys) are shown. The horizontal axis represents the light distribution angle, and the vertical axis represents the far-field light intensity at each light distribution angle when the power of the light source is 1.

[0160] In addition, for the three types of 106.38 μm (n=2), 212.77 μm (n=4), and 319.15 μm (n=6) where n in Formula A is 2, 4, and 6, simulations were also performed for the case where the distances were changed by 10 μm at intervals of 1 μm before and after. Figures 10 to 15 The results are shown.

[0161] From the simulation results, it can be seen that when the distance L is 53.19μm (n=1), 106.38μm (n=2), 159.67μm (n=3), 212.77μm (n=4), 265.96μm (n=5), and 319.15μm (n=6), the light intensity distribution shows good peaks. In addition, it can be seen that when n is an even number of 106.38μm (n=2), 212.77μm (n=4), and 319.15μm (n=6), the light intensity of each peak is also large. In addition, it can be seen that as long as the distance L satisfies formula 1, a relatively good peak can be maintained, and even if the distance L has a slight error, the light intensity is strong enough.

[0162] (Simulation 2)

[0163] The irradiation portion 1 is a wavelength of 940 nm and is Fig.16 (a) is a single light source with Gaussian light distribution. Fig.16 As shown in (b), the optical element 2 is a device in which lenses 21 with a height of 7 μm are arranged periodically with a pitch of 10 μm. In addition, the lens surface is non-arc-shaped. The material is set to PDMS with a refractive index of 1.53. The distance L uses five types of 53.2 μm (n=1), 106.4 μm (n=2), 212.8 μm (n=4), 319.1 μm (n=6), and 425.5 μm (n=8) when n in formula A is 1, 2, 4, 6, and 8. Fig.17The simulation results obtained using the optical simulation software BeamPROP (manufactured by Synopsys) are shown. The horizontal axis represents the light distribution angle, and the vertical axis represents the far-field light intensity at each light distribution angle when the power of the light source is 1.

[0164] From the simulation results, it can be seen that even if the optical element 2 is a device obtained by arranging a plurality of lenses 21, good peaks will appear when the distance L is 53.2 μm (n=1), 106.4 μm (n=2), 212.8 μm (n=4), 319.1 μm (n=6), and 425.5 μm (n=8), and the light intensity of each peak is also large. In addition, it can be seen that when n is an even number of 106.4 μm (n=2), 212.8 μm (n=4), 319.1 μm (n=6), and 425.5 μm (n=8), the light intensity of each peak is also large.

[0165] (Simulation 3)

[0166] The irradiation unit 1 is a light source 10 that irradiates light having a wavelength of 940 nm. Fig.18 (a) shows a plurality of light sources arranged in a square. In addition, the light emitted by the light source is Fig.18 (b) shows a bat-wing light distribution with a far field of Fig.18 (c) is a light with the intensity shown. Fig.19 As shown in (a), the optical element 2 is a device in which lenses 21 with a pitch of 20 μm are arranged in a square. Fig.19 As shown in (b), the shape of each lens 21 is a square with one side of 20 μm and a height of 9.86 μm when viewed from above. In addition, the lens surface is a non-rotationally symmetric aspheric surface with different curvatures in the x-axis direction and the y-axis direction. The material is set to PDMS with a refractive index of 1.53. The distance L is 212.8 μm (when n=1 in formula A), 425.5 μm (when n=2 in formula A), and 638.3 μm (when n=3 in formula A). Figure 20 to Figure 22 The simulation results obtained using the optical simulation software BeamPROP (manufactured by Synopsys) are shown. Figure 20 to Figure 22 (a) is a diagram showing a dot pattern 50 cm in front of the optical element 2. The size of the dot indicates the magnitude of the light intensity. Figure 20 to Figure 22 (b) shows Figure 20 to Figure 22 (a) The far-field light intensity of the light on the x-axis, Figure 20 to Figure 22 (c) shows Figure 20 to Figure 22 The far-field light intensity of the light on the y-axis of (a). In addition, the horizontal axis is the light distribution angle, and the vertical axis is the far-field light intensity at each light distribution angle when the power of the light source is 1.

[0167] Furthermore, as a comparative example, a simulation was performed on a case where a diffuser capable of forming an irradiation pattern having substantially the same shape as the above-described dot pattern was used. Fig.23 The simulation results obtained using the optical simulation software LightTools (manufactured by Synopsys) are shown. Fig.23 (a) is a diagram showing the irradiation pattern at 50 cm in front of the diffuser. Fig.23 (b) shows Fig.23 (a) The far-field light intensity of the light on the x-axis, Fig.23 (c) shows Fig.23 (a) Far-field light intensity of light on the y-axis.

[0168] From the simulation results, it can be seen that the dot pattern has good peaks and the light intensity of each peak is also large. It can also be seen that the light intensity of each peak is much larger than that of the device using a diffuser. In addition, when the lenses of the optical element 2 are arranged in a square, there is also a 28.3μm spacing in the diagonal direction. Since this spacing satisfies the formula A, L is 425.5μm, so it can be seen that Fig. 20 Compared with the results of Fig.21 The result is better alignment of the peaks and greater light intensity.

[0169] (Simulation 4)

[0170] The irradiation unit 1 is a light source that irradiates light with a wavelength of 940 nm. Fig.24 (a) shows a plurality of light sources arranged in a hexagonal pattern. Fig.24 (b) shows a bat-wing light distribution with a far field of Fig.24 (c) is a light with the intensity shown. Fig.25 As shown in (a), the optical element 2 is a device in which lenses 21 with a pitch of 22.5 μm are arranged in a hexagonal pattern. Fig.25 As shown in (b), the shape of each lens 21 is a regular hexagon when viewed from above and the height is 12.9μm. In addition, the lens surface is a non-rotationally symmetric aspheric surface with different curvatures in the x-axis direction and the y-axis direction. The material is set to PDMS with a refractive index of 1.53. The distance L is 269.3μm (when n=1 in formula A), 538.6μm (when n=2 in formula A), and 807.8μm (when n=3 in formula A). Figures 26-28 The simulation results obtained using the optical simulation software BeamPROP (manufactured by Synopsys) are shown. Figures 26-28 (a) is a diagram showing a dot pattern 50 cm in front of the optical element 2. The size of the dot indicates the magnitude of the light intensity. Figures 26-28 (b) shows Figures 26-28 (a) The far-field light intensity of the light on the x-axis, Figures 26-28 (c) shows Figures 26-28 The far-field light intensity of the light on the y-axis of (a). In addition, the horizontal axis is the light distribution angle, and the vertical axis is the far-field light intensity at each light distribution angle when the power of the light source is 1.

[0171] In addition, as a comparative example, Fig.29 The simulation results are shown in the case of using a diffuser that can form an irradiation pattern having substantially the same shape as the above-described dot pattern. Fig.29 (a) is a diagram showing the irradiation pattern at 50 cm in front of the diffuser. Fig.29 (b) shows Fig.29 (a) The far-field light intensity of the light on the x-axis, Fig.29 (c) shows Fig.29 (a) Far-field light intensity of light on the y-axis.

[0172] From the simulation results, it can be seen that the dot pattern has good peaks and the light intensity of each peak is also large. In addition, it can be seen that the light intensity of each peak is much larger than that of the device using a diffuser.

[0173] (Repetition rate of transmitted light)

[0174] In addition, the lens shape of the optical element 2 was further studied. It is known that when light transmitted through different positions on the surface of the lens 21 is emitted in the same direction, interference occurs, which causes a decrease in the contrast of the point. Therefore, it is more preferable that the optical element is designed so that the repetition rate of the emission direction of the transmitted light from the lens 21 is reduced.

[0175] (lens shape)

[0176] Here, the emission direction of the transmitted light from the lens is determined by the slope of the lens surface. That is, the repetition rate of the emission direction of the transmitted light from the lens is synonymous with the repetition rate of the normal direction of the lens surface. Therefore, in order to reduce the repetition rate of the emission direction of the transmitted light from the lens, it is sufficient to make the lens 21 a shape in which the repetition rate of the normal direction of the surface is reduced. For example, if the lens 21 has an inflection point or a singular point on a line in the surface cross section of the lens 21 where the lens 21 changes from a concave shape to a convex shape or from a convex shape to a concave shape, then a surface with a repetitive normal direction is generated in the concave and convex parts located before and after it.

[0177] (Simulation 5)

[0178] Fig.30 shows an example of a lens with an inflection point, Fig.31 An example of a lens without an inflection point is shown. Fig.30 (a) is a lens having a shape obtained by rotating the curve of y=sinx about the y axis and having an inflection point in the circled portion in the figure. Fig.31(a) is a lens with no inflection point and a shape obtained by rotating the curve of y=2|sinx| about the y axis. Fig.30 (b) Fig.31 (b) shows the far-field light intensity of the dot pattern when an optical element obtained by periodically arranging the lenses is used. The irradiation section 1 is an irradiation section having an irradiation wavelength of 940 nm and Fig.16 (a) is a single light source with Gaussian light distribution. Fig.16 As shown in (b), the optical element 2 is a device in which lenses 21 with a height of 10 μm are arranged periodically at a pitch of 10 μm. The material is PDMS with a refractive index of 1.53. The distance L is 106.4 μm (n=2) when n in formula A is 2. Fig.31 (b) Fig.32 (b) shows the simulation results obtained using the optical simulation software BeamPROP (manufactured by Synopsys Inc.) The horizontal axis represents the light distribution angle, and the vertical axis represents the far-field light intensity at each light distribution angle when the power of the light source is 1.

[0179] Fig.30 The lens shown in (a) has an inflection point in the cross-sectional shape of the lens, so the shape of the lens changes from concave to convex or from convex to concave in this part. In this case, a region is generated in which the light transmitted through the convex portion and the light transmitted through the concave portion travel in the same direction, so as shown in FIG. Fig.30 As shown in (b), noise light is generated due to interference between points, which is the main reason for the reduction of contrast. Fig.31 The lens shown in (a) has no inflection point in the cross-sectional shape of the lens, so the shape of the lens is composed only of convex parts. In this case, the transmitted light is not repeated, so Fig.31 Therefore, it is more preferable that there are no inflection points or singular points on the line in the surface cross section of the lens 21, and even if there are such points, it is preferable that either the concave portion or the convex portion has a sufficiently large shape.

[0180] In addition, the repetition rate of the normal direction of the surface of the lens 21 can be measured as follows.

[0181] (1) Fig.32 As shown in (a), the lens 21 is divided into n square fine regions 210 in a top view (xy plane). Then, each fine region 210 is labeled with a non-repeating number 1 to n. In addition, the size of one side of the fine region 210 is set to be at least one quarter (λ / 4) of the wavelength of the light of the irradiation part.

[0182] (2) Fig.32As shown in (a), the center point of the i-th (i=1, 2, ..., n) fine region among the divided fine regions 210 is denoted as Pi, and the inscribed circle is denoted as C. i In addition, the center point group of the fine regions other than the i-th one among the fine regions 210 obtained by segmentation is set as Q i .

[0183] (3) Fig.32 (b) will pass through point P i The normal vector at the intersection of the line perpendicular to the xy plane (the line parallel to the z axis) and the lens surface is set to N pi , will pass through circle C i The normal vector group at the intersection of the line perpendicular to the xy plane (the line parallel to the z axis) and the lens surface is set to N ci Then, if Fig.32 As shown in (c), N pi With N ci The minimum value of the angle formed is set to δθ i .

[0184] (4) Fig.32 (b) will pass through the point group Q i The normal vector group at the intersection of the line perpendicular to the xy plane (the line parallel to the z axis) and the lens surface is set to N qi .

[0185] (5) The state flag of the i-th fine region in the fine region 210 obtained by segmentation is set to F i 、F i The initial value of is set to 0.

[0186] (6) Fig.32 As shown in (d), for all i=1, 2, ..., n, the normal vector N is calculated. pi With vector group N qi The angle θ i , in θ i <δθ i In the case of i Set to 1.

[0187] (7) F i When the number of 1s is m, the normal line repetition rate can be obtained by (m / n)×100(%). The normal line repetition rate converges when n is made infinite (n→∞).

[0188] (Simulation 6)

[0189] Next, the relationship between the normal repetition rate of the lens shape and the light intensity distribution in the far field was simulated. In the simulation, six types of lenses were used as models. In the lens shape formula described later, the optical axis direction is represented as the z-axis, and the directions orthogonal to the z-axis are represented as the x-axis and the y-axis. In addition, the irradiation unit 1 is a light source 10 that irradiates light with a wavelength of 940nm. Fig.18 (a) shows a plurality of light sources arranged in a square. Fig.18 (b) shows a bat-wing light distribution with a far field of Fig.18 (c) Light with a light intensity as shown. The optical element 2 is a device in which lenses 21 having a plane shape of a square of x=20μm, y=20μm and a pitch of 20μm are arranged in a square. The material is set to PDMS with a refractive index of 1.53. The distance L is 425.5μm (when n=2 in formula A). In the simulation, the optical simulation software BeamPROP (manufactured by Synopsys) was used.

[0190] (Model 1)

[0191] As model 1, Fig.33 The shape of the lens is shown in the following formula.

[0192] (number 7)

[0193]

[0194] Fig.33 The white area in (b) is the area where the normal lines do not repeat, and the normal line repetition rate is 0%. Fig.33 (c) and (d) show the far-field light intensity. It can be seen that there is almost no noise light and the peak light intensity is also strong overall.

[0195] (Model 2)

[0196] As model 2, Fig.34 The shape of the lens is shown in the following formula.

[0197] (number 8)

[0198]

[0199] Fig.34 The black area in (b) is the area where the normal lines repeat, and the normal line repetition rate is 5.3%. Fig.34 (c) and (d) show the far-field light intensity. It can be seen that there is less noise light, but the peak light intensity is slightly lower than that of model 1.

[0200] (Model 3)

[0201] As Model 3, Fig.35 The shape of the lens is shown in the following formula.

[0202] (number 9)

[0203]

[0204] Fig.35 The black area in (b) is the area where the normal lines repeat, and the normal line repetition rate is 12.8%. Fig.35 (c) and (d) show the far-field light intensity. It can be seen that the normal line repetition rate exceeds 10% compared to Model 1, and the peak light intensity is further reduced compared to Model 1 or Model 2.

[0205] (Model 4)

[0206] As model 4, Fig.36 The shape of the lens is shown in the following formula.

[0207] (number 10)

[0208]

[0209] Fig.36 The black area in (b) is the area where the normal lines repeat, and the normal repetition rate is 49.8%. Fig.36 (c) and (d) show the far-field light intensity. It can be seen that compared with model 3, the normal line repetition rate is further increased, and the overall light intensity is weaker.

[0210] (Model 5)

[0211] As model 5, Fig.37 The shape of the lens is shown in the following formula.

[0212] (number 11)

[0213]

[0214] Fig.37 The black area in (b) is the area where the normal lines repeat, and the normal repetition rate is 62.2%. Fig.37 (c) and (d) show the far-field light intensity. It can be seen that compared with model 4, the normal line repetition rate is further increased, the noise light increases, and the overall light intensity is weaker.

[0215] (Model 6)

[0216] As Model 6, Fig.38 The shape of the lens is shown in the following formula.

[0217] (Number 12)

[0218]

[0219] Fig.38 The white area in (b) is the area where the normal lines do not repeat, and the normal line repetition rate is 0%. Fig.38 (c) and (d) show the far-field light intensity. It can be seen that there is almost no noise light and the peak light intensity is also strong overall.

[0220] Based on the above results, the surface of the lens 21 is a shape with a repetition rate in the normal direction of 10% or less, preferably 5% or less, and more preferably 3% or less. In addition, with respect to the surface of the lens 21, the far-field repetition rate of the transmitted light from the lens 21 is 10% or less, preferably 5% or less, and more preferably 3% or less.

[0221] (Perforated Baffle)

[0222] In addition, there are cases where it is difficult to design a lens shape with a low repetition rate of transmitted light as described above. In addition, even if a lens shape with a low repetition rate of transmitted light can be designed, it is sometimes difficult to reproduce such a lens shape in manufacturing. In such a case, the optical system device may also have a porous mask 7 that shields a part of the light, and the porous mask 7 has an opening 70. Specifically, the following porous mask 7 can be used: it has an opening 70 that allows the required transmitted light (hereinafter referred to as effective light) to pass through, and shields the transmitted light (hereinafter referred to as noise light) that is noise. Here, effective light refers to light that helps to form a dot pattern. Therefore, the opening 70 is formed in a portion that at least includes the optical axis of the lens. In addition, it is preferred that the size of the opening 70 is formed to be a size that allows the effective light to be transmitted as much as possible. In addition, noise light refers to light that increases the repetition rate. The distance between the lens and the porous mask 7 can be arbitrary as long as the noise light can be shielded, but it is desirable to configure it closer to the lens side than the range where the optical paths of the effective light of adjacent lenses overlap. For example, when adjacent lenses are in contact with each other, the effective light of each lens overlaps when it exceeds twice the distance to the focus of the lens. Therefore, it is preferable to arrange the porous mask 7 closer to the lens than twice the distance to the focal point of the lens. Also, when the opening 70 of the porous mask 7 is arranged at the focal position, the opening 70 can be minimized and most of the noise light can be shielded, which is preferable.

[0223] In addition, for example, the boundary portions between the lenses 21 may become singular points, and light may be scattered, which may cause noise light. In addition, for example, when the lenses 21 are formed by an imprinting method, deformation may easily occur at the boundary portions between the lenses 21, which may easily cause an increase in the repetition rate of the transmitted light. Therefore, a porous baffle 7 that shields the transmitted light of the lens 21 may be formed at the boundary portions of such lenses 21. In addition, the porous baffle 7 may also be arranged between the light source and the optical element. For example, a porous baffle 7 that shields the light from the light source may be formed at the boundary portions of the lenses 21.

[0224] In addition, the shape of the opening 70 of the porous baffle 7 can be any shape as long as it allows effective light to pass through, and can be any shape such as circular, elliptical, quadrilateral, hexagonal, etc. In addition, the opening 70 can be formed in each lens, and the openings 70 of each lens can also be connected to each other.

[0225] In addition, the material of the porous baffle 7 can be any material as long as it can suppress the transmission of light. For example, an absorbing material that absorbs light from the irradiation part or a reflecting material that reflects the light can be used. As the absorbing material that absorbs light, for example, a black photoresist layer can be used. In addition, as the reflecting material that reflects light, for example, metals such as silver, aluminum, and chromium oxide can be used.

[0226] In addition, the porous baffle 7 may be formed separately from the optical element, or may be formed integrally with the optical element.

[0227] (Simulation 7)

[0228] The influence of the presence or absence of the porous mask 7 on the noise light was simulated. The irradiation unit 1 is a light source 10 that irradiates light with a wavelength of 940 nm. Fig.18 (a) shows a plurality of light sources arranged in a square. Fig.18 (b) shows a bat-wing light distribution with a far field of Fig.18 (c) is a light with the intensity shown. Fig.39 As shown in (a), the optical element 2 is a device in which lenses 21 with a pitch of 33 μm are arranged in a square. Fig.39 As shown in (b), the shape of each lens 21 is expressed by the following formula:

[0229] (Number 13)

[0230]

[0231] When viewed from above, it is a square with one side of 33 μm and a height of 17.5 μm. The distance on the optical axis to the focus of the lens is 68.5 μm. In addition, when the lens is made by the imprinting method, the cross-sectional shape of the boundary portion of the lens, which is prone to become a singular point, is a parabola with a width of 1.5 μm, in which the boundary is the minimum value and is smoothly connected to the lens shape of the above formula. The material is set to PDMS with a refractive index of 1.53. The distance L between the light source and the optical element is 1158.5 μm (when n=2 in formula A). As Fig.39 As shown in (c), the porous mask 7 is a member in which circular openings 70 with a diameter of 16.5 μm are arranged in a square. Fig.39 As shown in (a), the porous mask 7 is arranged so that the center of the opening 70 becomes the focal point of the lens. Regarding the influence of the porous mask 7 on the noise light caused by the presence or absence of the porous mask 7, Fig.40 shows the dot pattern without the porous mask 7, Fig.41 The dot pattern in the case of having a multi-aperture mask 7 is shown. The dot pattern is a pattern on a 70 cm x 70 cm photosensitive plate 50 cm away from the optical element. In the simulation, optical simulation software BeamPROP (manufactured by Synopsys) was used.

[0232] like Fig.40 As shown in FIG. 1 , it can be seen that in the absence of the porous mask 7, a small point as noise light is generated between points near the center. Fig.41 As shown, it can be seen that when the porous mask 7 is arranged, no dots due to noise light are generated between dots near the center, and a good dot pattern is formed.

[0233] (Simulation 8)

[0234] Next, the relationship between the porous baffle 7 and the light intensity distribution in the far field was simulated. In the simulation, four lenses were used as models. In addition, when the plane shape of the lens is a square with x=20μm and y=20μm, the pitch is also 20μm. In addition, in the simulation, the optical simulation software BeamPROP (manufactured by Synopsys) was used.

[0235] (Model 1)

[0236] Fig.42 (a) shows the model 1 without the porous baffle 7, the lens period is 10 μm, the lens height is 5 μm, and the shape of the boundary part of the lens that is likely to become a singular point when the lens is made by the imprint method is an arc with a radius of 0.5 μm. Fig.42 (b) shows the light intensity in this case. It can be seen that a small peak as noise light occurs between peaks near the center.

[0237] (Model 2)

[0238] then, Fig.43 (a) shows a model 2 in which a porous mask 7 for shielding the transmitted light from the lens 21 is formed on the bottom side of the boundary portion of the lens 21. The width of the porous mask 7 is set to 1 μm based on the width of an arc with a radius of 0.5 μm. In addition, the thickness of the shielding portion is 0.5 μm. Fig.43 (b) shows the light intensity in this case. It can be seen that, compared with the model 1 without the porous mask 7, almost no noise light is generated in the center.

[0239] (Model 3)

[0240] In the lens of model 1, the arc-shaped portion of the boundary portion is easily deformed when produced by the imprint method. Fig.44 As shown in (a), the arc-shaped portion of the lens of model 1 is made into a flat shape with a width of 1 μm, thereby forming model 3. In model 3, a porous mask 7 is formed on the bottom side of the boundary portion of lens 21 to shield the transmitted light from lens 21. The width of the porous mask 7 is set to 1 μm according to the width of the flat portion. In addition, the thickness of the shielding portion is 0.5 μm. Fig.44 (b) shows the light intensity in this case. It can be seen that, compared with the model without the porous mask 7, almost no noise light is generated in the center.

[0241] (Model 4)

[0242] then, Fig.45 (a) shows a model 4 in which a porous mask 7 for shielding light from a light source is formed on the surface of the boundary portion of the lens 21. The width of the porous mask 7 is set to 1 μm so as to shield all light incident on an arc with a radius of 0.5 μm. Fig.45 (b) shows the light intensity in this case. It can be seen that, compared with the model 1 without the porous mask 7, almost no noise light is generated in the center.

[0243] (Light diffusion part)

[0244] In addition, the optical element may also be formed with a light diffusion portion 8 at the boundary portion of the lens that refracts the transmitted light to the outside of the illumination angle of the lens (outside of the illumination range of the dot pattern). Thus, the noise light can be excluded to the outside of the dot pattern, so a good dot pattern can be obtained. As long as the incident light can be refracted to the outside of the illumination angle of the lens, the shape of the light diffusion portion 8 can be any shape, and any shape that is easy to manufacture can be selected. For example, a cross-sectional shape on a surface parallel to the boundary of the lens can be a triangular shape.

[0245] (Simulation 9)

[0246] The influence of the light diffusion unit 8 on the noise light was simulated. Fig.46 As shown in (a), the lens is formed to have a light diffusion portion 8 at the boundary portion of the lens used for simulation 7. The light diffusion portion 8 is formed around the lens with a width of 1.5 μm from the boundary. Fig.46 As shown in (b), the cross-sectional shape of the light diffusion portion 8 (the cross-sectional shape parallel to the nearest boundary of the lens) is a concave-convex structure formed by juxtaposing similar triangles with the same base width and height and an aspect ratio of 1. The similar triangles are juxtaposed in such a way that the base position of the triangle coincides with the position of the bottom surface of the lens. The other conditions are set to be the same as those of simulation 7. Fig.47 The dot pattern in the case of including the light diffusion unit 8 is shown.

[0247] like Fig.47 As shown, it can be seen that when the light diffusion section 8 is arranged, dots due to noise light are hardly generated between dots, and a good dot pattern is formed.

[0248] (Optical element manufacturing method)

[0249] The manufacturing method of the optical element is described. The lens 21 of the optical element 2 can be manufactured in any manner, for example, it can be manufactured using an imprinting method. Specifically, the material of the lens 21 is coated on the substrate 25 with a predetermined film thickness using a known method such as a spin coater (coating process). As a material, any material can be used as long as it can form a lens 21 that transmits light with a wavelength of λ, for example, polydimethylsiloxane (PDMS) can be used.

[0250] Next, a mold having a reverse pattern of a pattern obtained by periodically arranging the lenses 21 is prepared, and the mold is pressed against the coated material on the substrate 25 to transfer the pattern (imprinting process). In addition, when forming an optical element having the above-mentioned light diffusion portion 8, a mold having a reverse pattern of the light diffusion portion 8 together with the above-mentioned pattern can be used.

[0251] This makes it possible to manufacture an optical element in which the variation in the height direction of the lens 21 is small, and thus it is possible to reduce the error in the distance L1.

[0252] In addition, when the optical element forms the porous mask 7, a porous mask forming step is included. First, a case where the porous mask 7 is formed so as to be arranged in the optical path of the noise light of the lens 21 will be described.

[0253] (1) Fig.48As shown in (a), a porous mask 7 for preventing light transmission is formed on the substrate 25 at least at a predetermined distance from a position corresponding to the optical axis of the lens 21 (porous mask forming step). The porous mask 7 can be formed by any method, for example, by the following method.

[0254] (1.1) A film made of a light shielding material is formed on the substrate 25. The film can be formed by a method such as chemical vapor deposition (CVD) or by coating.

[0255] (1.2) A photoresist layer is coated on a film made of a light-shielding material, and the photoresist layer is formed at positions other than the opening of the porous mask using existing techniques such as photolithography or imprinting. The size of the opening 70 can be formed to allow effective light to pass as much as possible. The light-shielding material is etched using the photoresist layer, and the remaining photoresist layer is removed by ashing or the like, thereby forming the porous mask 7.

[0256] As the light-shielding material, any material can be used as long as it can block the light to be used, for example, metals such as silver, aluminum, and chromium oxide, or resins such as black photoresist layers can be used.

[0257] (2) Fig.48 As shown in FIG. 2( b ), after the porous mask 7 is formed on the substrate 25, a transparent film 26 for adjusting the distance between the lens 21 and the porous mask 7 is formed. The transparent film 26 can be formed in any manner, for example, by coating a transparent material with a predetermined film thickness on the substrate 25 using a known method such as a spin coater. Any material can be used as long as it can transmit light with a wavelength of λ, for example, polydimethylsiloxane (PDMS) can be used.

[0258] (3) Fig.48 As shown in (c), after forming the transparent film 26 on the substrate 25, the lens 21 is formed (lens forming step). The lens can be formed by any method, for example, by aligning with the porous mask 7 and using existing techniques such as embossing to form the lens 21. In this case, the distance between the lens 21 and the porous mask 7 is determined by the size of the transparent film 26 and the residual film produced by embossing. Fig.48 As shown in (d), a porous mask 7 can be formed integrally with the optical element 2. Furthermore, the distance between the lens 21 and the porous mask 7 can be adjusted by adjusting the size of the residual film produced by imprinting without forming the transparent film 26.

[0259] In addition, if Fig.49 As shown in (c), when a porous mask 7 for shielding the transmitted light from the lens is formed at the boundary portion of the lens 21 and on the transmitted light side of the lens, it can be formed by the following method.

[0260] (1) Fig.49 As shown in (a), a porous mask 7 for preventing light transmission is formed on the substrate 25 at a position corresponding to the boundary of the lens (porous mask forming step). The porous mask 7 can be formed by any conventional method, for example, by the following method.

[0261] (1.1) A film made of a light shielding material is formed on the substrate 25. The film can be formed by a method such as chemical vapor deposition (CVD) or by coating.

[0262] (1.2) A photoresist layer is coated on a film made of a light-shielding material, and a photoresist layer is formed only at a position corresponding to the boundary of the lens with a desired width capable of shielding noise light using existing techniques such as photolithography or imprinting. The light-shielding material is etched using the photoresist layer, and the remaining photoresist layer is removed by ashing, etc., to form a porous baffle 7.

[0263] As the light shielding material, any material can be used as long as it can shield the light to be used, and for example, metals such as silver, aluminum, and chromium oxide, or resins such as black photoresist layers can be used.

[0264] (2) Fig.49 As shown in (b), after the porous mask 7 is formed on the substrate 25, the lens 21 is formed in such a way that the boundary of the lens 21 is arranged on the porous mask 7 (lens forming step). The lens 21 can be formed by any method, for example, the lens 21 can be formed by aligning with the porous mask 7 using an existing technique such as an imprint method. Fig.49 As shown in (c), a porous mask 7 can be formed integrally with the optical element 2.

[0265] In addition, if Fig.50 As shown in (c), when a porous mask 7 for shielding light from the light source is formed at the boundary portion of the lens 21 and on the light source side of the lens, it can be formed by the following method.

[0266] (1) An optical element is prepared in which lenses 21 are periodically arranged. The lenses 21 of the optical element can be formed in any manner, and for example, an existing technique such as an imprint method can be used.

[0267] (2) Then, Fig.50 As shown in (a), a light-shielding material that prevents light transmission is applied to all or part of the lens 21 to form a light-shielding film 27. Fig.50As shown in (b), the light shielding material is removed at a position corresponding to the boundary of the lens 21 so that a part of the light shielding material remains, thereby forming a porous baffle 7 (porous baffle forming step). For example, a light shielding material such as a black photoresist layer is applied to the lens 21. By etching back the light shielding material by a desired amount, an optical element can be formed in which the light shielding material remains only in the groove portion corresponding to the boundary of the lens 21.

[0268] As the light shielding material, any material can be used as long as it can shield the light used and has a sufficiently high etching rate for the lens 21. Here, a sufficiently high etching rate means a degree that does not affect the optical characteristics of the lens 21.

[0269] As long as the etching back can be performed, any etching method can be used, for example, reactive ion etching (RIE) or chemical dry etching (CDE) can be used. Fig.50 As shown in (c), a porous mask 7 is formed integrally with the optical element 2.

[0270] (Pitch of irradiated parts)

[0271] When the irradiation unit 1 has a plurality of light sources 10, even if each light source 10 is moved parallel to the optical element 2, it is necessary to arrange the light sources 10 in the same number relative to each lens 21 of the optical element 2 in a top view. Specifically, when m is a natural number greater than 1, the irradiation unit can regularly arrange the plurality of light sources in any period direction of the lens 21 of the optical element at m times or 1 / m times the period. In other words, the light sources 10 of the irradiation unit 1 can be arranged at a pitch P of 1 / m on the lens 21 of the optical element 2. k In the direction of the spacing mP k or P k In particular, the pitch can be set to mP1 or P1 / m. Fig.51 In (a) and (b), m=1 is set so that the pitch of the light source 10 is equal to the pitch P1 of the lens 21 of the optical element 2. In addition, Fig.51 In (c), m=2 is set so that the pitch of the light source 10 is 1 / 2 of the pitch P1 of the lens 21 of the optical element 2, that is, P1 / 2. Fig.51 In (d), m=2 is set so that the pitch of the light sources 10 is twice the pitch P1 of the lenses 21 of the optical element 2, that is, 2P1.

[0272] In addition, when the irradiation unit 1 is a device in which the light sources 10 are arranged in a hexagonal pattern, the planar shape of the lens 21 of the optical element is a rectangle, and the ratio of the short side to the long side of the rectangle is When the pitch of the light sources 10 is mP1 or P1 / m, the number of light sources 10 relative to each lens 21 becomes uniform, which is preferred. In this case, since the smallest pitch P1 (the size of the short side of the rectangle) and the second smallest pitch P2 (the size of the long side of the rectangle) satisfy equation 1, It is preferred that the distance L1 between the irradiation unit 1 and the optical element 2 is

[0273] (Number 14)

[0274]

[0275] More preferably

[0276] (number 15)

[0277]

[0278] In addition, if Fig.52 As shown, the light from the irradiation unit 1 does not need to be directly irradiated to the optical element 2, but can also be irradiated via a reflector 3 that reflects the light from the irradiation unit 1. In this case, the distance L1 between the irradiation unit 1 and the optical element 2 refers to the actual distance. Therefore, Fig.52 The distance L1 in the case becomes the sum of the distance La from the irradiation unit 1 to the reflector 3 and the distance Lb from the reflector 3 to the optical element 2, that is, La+Lb. Thus, the distance L can be adjusted using the reflector 3. In addition, the direction of the light from the light source can also be adjusted.

[0279] Next, another embodiment of the present invention will be described. Fig.53 (a) is a schematic plan view of the irradiation unit 1 as viewed from the optical element 2. Here, the optical element 2 is a device in which lenses 21 having a rectangular planar shape are regularly arranged. In addition, the irradiation unit 1 uses a device in which the light sources 10 are arranged in a hexagonal pattern. Fig.53 The configuration of the light source 10 shown in (a) can be decomposed as follows: Fig.53 (b) is divided into 4. Fig.53 The dot patterns emitted by the configurations of the light sources 10 at the upper left and lower left, and at the upper right and lower right of (b) are the same, and therefore can be considered the same. Therefore, the configuration of the light source 10 relative to the optical element 2 can be substantially divided into Fig.53 (c) Two types shown.

[0280] Therefore, if Fig.54As shown, the same light distribution can be achieved by making the irradiation unit 1 include a first irradiation unit 1A and a second irradiation unit 1B. The first irradiation unit 1A is obtained by regularly arranging a plurality of light sources 10 irradiating light of wavelength λ, and the second irradiation unit 1B is obtained by regularly arranging a plurality of light sources 10 irradiating light of wavelength λ in a manner that is staggered by half a period in the longitudinal and lateral directions with the light sources 10 of the first irradiation unit 1A. In this case, as compared Fig.53 As can be seen from (a) and (c), there is an advantage in that the interval between the light sources 10 of the irradiation unit 1 can be doubled.

[0281] Alternatively, the irradiation unit 1 may include a first irradiation unit, a second irradiation unit, and a third irradiation unit, each of which is formed by regularly arranging a plurality of light sources 10 irradiating light of wavelength λ, and each irradiation unit may be spaced at a pitch P between the lens 21 of the optical element 2. k In the direction of each staggered P k / 3. For example, Fig.55 (a) shows a case where the optical element 2 is a device in which lenses 21 having a rectangular planar shape are regularly arranged, and the irradiation unit 1 uses a device in which the light sources 10 are arranged in a hexagonal pattern. Fig.55 As shown in (b) to (d), Fig.55 The irradiation unit 1 shown in (a) can include three devices, namely, a first irradiation unit 11, a second irradiation unit 12, and a third irradiation unit 13, in which the light sources 10 are arranged in a manner staggered by P2 / 3 in the direction of the lens pitch P2 of the optical element 2. Fig.56 As shown, the optical element 2 and the three devices of the first irradiation unit 11, the second irradiation unit 12 and the third irradiation unit 13 constitute an optical system device, thereby not reducing the light intensity of the irradiation unit, but increasing the number of emitted points by three times. In addition, when the resolution of the light receiving sensor used for TOF is low, even if the number of points is tripled, sometimes it is impossible to sense all of them. In this case, the irradiation unit can also make the first irradiation unit, the second irradiation unit and the third irradiation unit emit light in sequence in a staggered manner. Thus, by performing three measurements with the light receiving sensor, the resolution can be increased by three times.

[0282] In addition, when the planar shape of the lens 21 is a square or rectangle with a length of R on one side, the arrangement of the lens 21 may be such that, when i is a natural number greater than 1, the rows of lenses 21 that are continuous in the direction of the side are arranged so as to be staggered by R / i. In this way, the number of emission points can be multiplied by i.

[0283] This principle can be explained as follows. Here, the irradiation unit 1 is a device in which light sources 10 irradiating light with a wavelength of 940 nm are arranged hexagonally with a minimum pitch of 21 μm. In addition, the size of the light source 10 is 10 μm. In addition, the plane shape of the lens 21 of the optical element 2 is a rectangle with a length of 21 μm and a width of 36.4 μm. In addition, the distance between the irradiation unit 1 and the optical element 2 is 1407 μm. Fig.57 As shown in (a), when the lenses 21 in adjacent rows of the optical element 2 are arranged in the same manner, if the positions of the light source 10 relative to the lenses 21 are synthesized, it becomes Fig.57 As shown in (b), the light from the light source 10 is divided into two per lens 21. In this case, the irradiated dot pattern is as follows: Fig.57 (c). On the other hand, Fig.58 As shown in (a), when the lenses 21 in adjacent rows of the optical element 2 are arranged so as to be staggered by R / 2, if the positions of the light source 10 relative to the lenses 21 are synthesized, the result is Fig.58 As shown in (b), the light from the light source 10 per lens 21 becomes four. In this case, the light from the light source 10 per lens 21 becomes twice, so the number of dots of the irradiated dot pattern is as follows: Fig.58 (c) is doubled. Fig.59 As shown in (a), when the lenses 21 of adjacent rows of the optical element 2 are arranged so as to be offset by R / 3, if the positions of the light source 10 relative to the lenses 21 are synthesized, it becomes Fig.59 As shown in (b), the number of dots of the light source 10 per lens 21 becomes 6. In this case, since the number of dots of the light source 10 per lens 21 becomes 3 times, the number of dots of the irradiated dot pattern is as follows: Fig.59 (c) is 3 times. In this way, when the lenses 21 of adjacent rows of the optical element 2 are arranged so as to be offset by R / i, if the light source 10 is synthesized with respect to each lens 21, the light of the light source 10 per lens 21 becomes 2i. Therefore, the light of the light source 10 per lens 21 becomes i times that of the case where the rows of adjacent lenses 21 are not completely offset, and the number of emitted points also becomes i times.

[0284] In addition, there is also a case where the optical element 2 of the present invention is used together with the conventional diffuser type optical element 5. In this case, Fig.60 As shown, the optical system device may also include: a diffuser, which diffuses the light of the irradiation part 1 into a specified shape; a half-reflective mirror, which is arranged between the light source 10 and the diffuser, so that a part of the light of the irradiation part 1 is transmitted and a part of the light of the irradiation part 1 is reflected; and a reflector, which reflects the light reflected by the half-reflective mirror 4 toward the optical element 2.

[0285] Furthermore, the optical element 2 according to the present invention can be used not only for irradiating a dot pattern but also for a diffuser.

[0286] like Fig.61 As shown, in the first method of using the optical element 2 as a diffuser, a diffuser irradiation unit 6 is prepared, which is arranged in the same manner as the irradiation unit 1 that uses a plurality of light sources 10 irradiating light of wavelength λ for dot pattern irradiation. Then, the distance L2 between the diffuser irradiation unit 6 and the optical element 2 satisfies the following formula 2.

[0287] (Number 16)

[0288]

[0289] Therefore, as in the above-mentioned simulation 1 and Figure 7 to Figure 9 As shown, it can be seen that the width of each peak increases and the non-uniformity of light intensity decreases.

[0290] Furthermore, it is more preferable that the distance L2 satisfies the following formula 3.

[0291] (Number 17)

[0292]

[0293] In this case, you can also Fig.61 (a) as shown in the common use of optical elements 2, it is also possible to Fig.61 As shown in (b), two devices, namely, an optical element 2a for a dot pattern and an optical element 2b for a diffuser, are used.

[0294] In the second method of using the optical element 2 as a diffuser, a diffuser irradiation unit 6 is prepared by arranging a plurality of light sources 60 that irradiate light of wavelength λ. When m is a natural number greater than 1, the diffuser irradiation unit 6 may arrange the plurality of light sources 60 in the period direction of the lens 21 of the optical element 2 so as not to be m times or 1 / m times the period.

[0295] In addition, if Fig.62 As shown in (a), there is also a case where the plurality of light sources 60 of the diffuser irradiation unit 6 is m times or 1 / m times the period. In this case, Fig.62 As shown in (b), the diffuser irradiation unit 6 can be rotated relative to the optical element in the optical axis direction of the light source 60. Thus, in the period direction of the lens 21 of the optical element 2, the plurality of light sources 60 can be staggered so as not to become m times or 1 / m times the period. Figure 63 to Figure 65The figure shows a state where the positions of the light source 60 relative to the lenses 21 when the light of the diffuser irradiation unit 6 is irradiated to the optical element 2 are combined into one lens 21. Here, the rotation angle θ is the distance mP between the light sources 10 of the diffuser irradiation unit 6. k or P k / m and the lens 21 of the optical element 2 has a spacing P k For example, Fig.62 As shown in (a), when the pitch of the irradiation unit 1 is consistent with the pitch of the optical element 2 (when θ is 0 degrees), the position of the light source 10 is the same in any lens 21, so Fig.63 As shown in (θ=0°), the positions of the light sources 10 overlap well. On the other hand, as the angle θ increases, the positions of the light sources 10 begin to deviate.

[0296] (Simulation 10)

[0297] The relationship between the rotation angle and the dot pattern relative to the optical element 2 was simulated. The irradiation part is a VCSEL with a hexagonal arrangement of 21μm pitch, a wavelength of 940nm, a divergence angle (FWHM) of 20 degrees, and an emitter pitch of 10μm. The refractive index of the optical element is 1.53, the pitch is a rectangle of 21μm×36.37μm, and the FOI is 60 degrees×45 degrees. In addition, the distance between the optical element and the irradiation part is 1407μm. In addition, the projection position of the dot pattern is 50cm in front of the optical element. The rotation angle θ relative to the optical element 2 is 0 degree, 1 degree, 5 degrees, 10 degrees, and 15 degrees. Figures 66 to 70 1 is a diagram showing the rotation angle and dot pattern with respect to the optical element 2. In the simulation, optical simulation software BeamPROP (manufactured by Synopsys) was used.

[0298] like Fig.66 As shown, it can be seen that when the period of the plurality of light sources 60 of the diffuser irradiation unit 6 and the lens of the optical element is consistent (the rotation angle is 0 degrees), a good dot pattern appears. On the contrary, as the rotation angle increases, the deviation between the period of the light source 60 and the period of the lens increases, the peak width becomes larger, and the light is diffused. Therefore, by appropriately adjusting the rotation angle θ of the diffuser irradiation unit 6 relative to the optical element, the optical element 2 can be used as a diffuser.

[0299] In addition, the third method of using the optical element 2 as a diffuser is a method of increasing the number of points in the dot pattern and making the irradiated light appear uniform. Here, appearing means, for example, increasing the number of points to a level above the resolution of the light receiving sensor that receives the reflected light of the irradiated light in the case of TOF. In order to increase the number of points in the dot pattern, as described above, the planar shape of the lens 21 is a square, rectangle, rhombus or parallelogram with a length of R on one side. In addition, regarding the arrangement of the lenses 21, the columns of lenses 21 that are continuous in the direction of the above-mentioned sides are arranged in a manner that is staggered by R / i. Then, i is adjusted so that the number of emitted points is above the resolution of the light receiving sensor.

[0300] The diffuser formed in this way can be used in combination with an optical system device for irradiating the above-mentioned dot pattern. As a result, the light intensity of the irradiated light can be ensured by the dot pattern for a distant object, and the distance or shape can be measured, while the light of the diffuser can be irradiated for a closer object, and the distance or shape can be measured more accurately.

Claims

1. An optical system device, characterized in that: include: An optical element obtained by periodically arranging lenses that transmit light having a wavelength λ; as well as an irradiation unit having a light source for irradiating light having a wavelength of λ toward a plurality of lenses among the lenses, When n is a natural number greater than 1, the size of the lens pitch from the smallest to the kth pitch is P k When any one or more spacings P k , the distance L1 between the irradiation part and the optical element satisfies the following formula 1: Where k is a natural number greater than 1. The lens is an aspherical lens in which the boundaries between the lenses are square, rectangular or hexagonal in a plan view and the repetition rate of the normal direction of the surface is 10% or less.

2. The optical system device according to claim 1, characterized in that: A porous mask having an opening is provided for shielding a part of noise light which increases the repetition rate of the emission direction of the transmitted light from the lens.

3. The optical system device according to claim 2, characterized in that: The porous mask has an opening at least in a portion including an optical axis of the lens.

4. The optical system device according to claim 2, characterized in that: The porous baffle is arranged in the optical path of the noise light of the lens.

5. The optical system device according to claim 2, characterized in that: The porous baffle is configured at a boundary portion of the lens.

6. The optical system device according to claim 2, characterized in that: The porous mask shields light irradiated to a boundary portion of the lens.

7. The optical system device according to claim 2, characterized in that: The porous baffle is formed integrally with the optical element.

8. The optical system device according to claim 1, characterized in that: The optical element has a light diffusion portion formed at a boundary portion of the lens, the light diffusion portion refracting the transmitted light to the outside of the irradiation angle of the lens.

9. The optical system device according to any one of claims 1 to 8, characterized in that: The smallest pitch P1 of the optical elements satisfies the equation 1, and the second smallest pitch P2 also satisfies the equation 1.

10. The optical system device according to claim 9, characterized in that: When m is a natural number greater than 1, the irradiation unit is obtained by arranging the light sources in a hexagonal manner with a pitch of mP1 or P1 / m, and the plane shape of the lens of the optical element is such that the ratio of the short side to the long side is rectangle.

11. The optical system device according to claim 10, characterized in that: The distance L1 between the irradiation part and the optical element is 3P1 2 A multiple of 1 or more of / 2λ.

12. The optical system device according to claim 1, characterized in that: A reflecting mirror is provided for reflecting the light from the irradiation part.

13. The optical system device according to claim 1, characterized in that: There are a plurality of the irradiation parts.

14. The optical system device according to claim 13, characterized in that: The irradiation part includes: a first irradiation part, which is obtained by regularly arranging multiple light sources that irradiate light with a wavelength of λ; and a second irradiation part, which is obtained by regularly arranging multiple light sources that irradiate light with a wavelength of λ in a manner that is staggered half a period in the longitudinal and transverse directions with the light sources of the first irradiation part.

15. The optical system device according to claim 13, characterized in that: The irradiation unit includes a first irradiation unit, a second irradiation unit, and a third irradiation unit obtained by regularly arranging a plurality of light sources irradiating light of wavelength λ, and a lens pitch P of the optical element is set. k In the direction, the light sources of the first irradiation unit, the second irradiation unit and the third irradiation unit are staggered by P k / 3 arrangement.

16. The optical system device according to claim 13, characterized in that: The irradiation unit is a device that causes each irradiation unit to emit light in sequence with a staggered time.

17. The optical system device according to claim 1, characterized in that: The plane shape of the lens is a square or rectangle with a length of R on one side. Regarding the arrangement of the lenses, when i is a natural number greater than or equal to 2, rows of lenses that are continuous in the direction of the side are arranged so as to be shifted by R / i.

18. The optical system device according to claim 1, characterized in that: The irradiation unit includes a VCSEL having a plurality of light emission modes, wherein a mode having a maximum intensity at a center of an optical axis accounts for 40% or more of the entire light emission modes.

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