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WO2025115667A1 - Élément de réflexion optique - Google Patents

Élément de réflexion optique Download PDF

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Publication number
WO2025115667A1
WO2025115667A1 PCT/JP2024/040760 JP2024040760W WO2025115667A1 WO 2025115667 A1 WO2025115667 A1 WO 2025115667A1 JP 2024040760 W JP2024040760 W JP 2024040760W WO 2025115667 A1 WO2025115667 A1 WO 2025115667A1
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WO
WIPO (PCT)
Prior art keywords
light
rib
ribs
reflecting element
optical reflecting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
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PCT/JP2024/040760
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English (en)
Japanese (ja)
Inventor
菜都美 呉坪
信一郎 能崎
健介 水原
雅春 深草
潤 滝川
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Publication of WO2025115667A1 publication Critical patent/WO2025115667A1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems

Definitions

  • the present invention relates to an optical reflecting element for scanning light.
  • optical reflecting elements that rotate a reflecting surface to scan light are known.
  • This type of optical reflecting element can be used, for example, in image display devices such as head-up displays.
  • a MEMS (Micro Electro Mechanical Systems) mirror is used as the optical reflecting element.
  • Such optical reflecting elements are provided with a structure for suppressing bending of the reflecting surface.
  • Patent Document 1 describes an optical scanning device in which intersecting linear ribs are formed on the underside of a plate-like movable part that rotates together with the reflective surface. With this configuration, the rigidity of the movable part is increased by the ribs, so that deflection of the movable part and the reflective surface on the upper surface of the movable part can be suppressed.
  • the present invention aims to provide an optical reflecting element that can suppress the effects of diffracted light caused by the ribs while reinforcing a movable part having a reflecting surface with ribs.
  • the optical reflecting element comprises a flat movable part that rotates about a rotation axis, a reflecting surface disposed on the upper surface of the movable part, and at least one rib disposed on the lower surface of the movable part.
  • the reflecting surface is irradiated with light whose intensity decreases with increasing distance from the central axis.
  • the rib in a specific area of the lower surface corresponding to the vicinity of the center of the light irradiated area on the reflecting surface has a substantially curved shape in a planar view.
  • ribs are disposed on the underside of the movable part, so that the movable part is reinforced by the ribs. This makes it possible to prevent bending of the movable part and the reflecting surface disposed on its upper surface. Furthermore, a rib having a substantially curved shape is disposed in a specific area on the underside of the movable part. Therefore, diffracted light caused by changes in the shape of the reflecting surface due to this rib is dispersed, making it difficult for peaks to occur in the diffracted light. This makes it possible to effectively prevent diffracted light from the light near the center, where the intensity is high, from affecting the light scanning.
  • the optical reflecting element comprises a flat movable part that rotates about a rotation axis, a reflecting surface arranged on the upper surface of the movable part, and at least one rib arranged on the lower surface of the movable part.
  • the reflecting surface is irradiated with light having a plurality of peak intensities near the central axis and decreasing in intensity with increasing distance from the position of each of the peak intensities.
  • the rib in a specific area of the lower surface corresponding to the vicinity of the center of the light irradiated area on the reflecting surface has a substantially curved shape in a planar view.
  • ribs are disposed on the underside of the movable part, so that the movable part is reinforced by the ribs. This makes it possible to prevent bending of the movable part and the reflecting surface disposed on its upper surface. Furthermore, a rib having a substantially curved shape is disposed in a specific area on the underside of the movable part. Therefore, diffracted light caused by changes in the shape of the reflecting surface due to this rib is dispersed, making it difficult for peaks to occur in the diffracted light. This makes it possible to effectively prevent diffracted light from the light near the center, where the intensity is high, from affecting the light scanning.
  • the optical reflecting element comprises a flat movable part that rotates about a rotation axis, a reflecting surface arranged on the upper surface of the movable part, a first rib arranged on the lower surface of the movable part and surrounding the center of the lower surface, and a second rib arranged on the lower surface outside the first rib and extending substantially parallel to the rotation axis.
  • the first rib has a substantially curved shape in a plan view, and no other ribs are provided inside the first rib.
  • the first rib and the second rib are disposed on the lower surface of the movable part, and the movable part is reinforced by these ribs. This makes it possible to suppress the occurrence of bending in the movable part and the reflective surface disposed on its upper surface.
  • the second rib is disposed substantially parallel to the rotation axis, the second rib can suppress the moment of inertia of the movable part rotating about the rotation axis from increasing. This allows the movable part to rotate smoothly.
  • only the first rib, which is substantially curved is disposed in the area surrounding the center of the lower surface of the movable part.
  • the shape change of the reflective surface due to the first rib also becomes a shape that substantially surrounds the center with a curve. Therefore, diffraction does not occur inside the shape change of the reflective surface, and the diffracted light generated by this shape change is dispersed and is less likely to produce a peak. This makes it possible to effectively suppress the effect of diffraction by the first rib on the light near the center where the intensity of the irradiated light is high.
  • the present invention provides an optical reflecting element that can suppress the effects of diffracted light caused by the ribs while reinforcing a movable part having a reflecting surface with the ribs.
  • FIG. 1 is a plan view showing the configuration of an optical reflecting element according to an embodiment.
  • FIG. 2 is a cross-sectional view showing the configuration of an optical reflecting element according to an embodiment.
  • FIG. 3 is a diagram illustrating a schematic structure of the lower surface 103b of the movable portion according to the embodiment.
  • FIG. 4 is a plan view showing the configuration of an optical deflector according to an embodiment.
  • FIG. 5 is a diagram showing a configuration of an optical scanning device 20 according to an embodiment.
  • FIG. 6 is a diagram illustrating a schematic view of a light irradiation area on a reflecting surface and a light intensity distribution in the irradiation area according to the embodiment.
  • Fig. 7A is a diagram showing a schematic configuration of a rib according to Comparative Example 1.
  • Fig. 7B is a diagram showing a simulation result according to Comparative Example 1.
  • Fig. 8(a) is a diagram showing a schematic configuration of a rib according to Example 1.
  • Fig. 8(b) is a diagram showing a simulation result according to Example 1.
  • Fig. 9(a) is a diagram showing a schematic diagram of a rib configuration according to Comparative Example 2.
  • Fig. 9(b) is a diagram showing a simulation result according to Comparative Example 2.
  • Fig. 9(c) is a diagram showing a schematic diagram of a rib configuration according to Comparative Example 3.
  • Fig. 9(d) is a diagram showing a simulation result according to Comparative Example 3.
  • Fig. 10(a) is a diagram showing a schematic configuration of a rib according to Example 2.
  • Fig. 10(b) is a diagram showing a simulation result according to Example 2.
  • Fig. 10(c) is a diagram showing a schematic configuration of a rib according to Example 3.
  • Fig. 10(d) is a diagram showing a simulation result according to Example 3.
  • FIG. 11 is a diagram showing a schematic arrangement of ribs according to the first modified example.
  • Fig. 12A is a diagram for explaining a simulation method according to Modification Example 1.
  • Fig. 12B is a diagram for explaining a method for acquiring parameter values indicating the intensity of diffracted light in a simulation according to Modification Example 1.
  • FIG. 13 is a graph showing a simulation result according to the first modification.
  • 14A and 14B are diagrams illustrating another method of arranging ribs according to the first modified example.
  • FIG. 15(a) and 15(b) are diagrams each showing a schematic diagram of a rib arrangement method according to a second modification and a third modification, respectively.
  • FIG. 16 is a diagram illustrating a schematic view of a light irradiation area on a reflecting surface and a light intensity distribution in the irradiation area according to the second modification.
  • 17(a) and 17(b) are diagrams each showing a schematic diagram of a rib arrangement method according to a fourth and fifth modified examples, respectively.
  • 18(a) and 18(b) are diagrams each showing a schematic diagram of a rib arrangement method according to Modification Example 6 and Modification Example 7. In FIG.
  • FIG. 19(a) and 19(b) are diagrams each showing a schematic diagram of a rib arrangement method according to Modification Example 8 and Modification Example 9.
  • FIG. Fig. 20A is an enlarged cross-sectional view of the movable portion and its surroundings according to the embodiment
  • Fig. 20B is an enlarged cross-sectional view of the movable portion and its surroundings according to a tenth modified example.
  • FIG. 21 is a diagram illustrating a schematic view of an irradiated area of a reflecting surface and a light intensity distribution in the irradiated area according to the eleventh modification.
  • 22A to 22C are diagrams showing simulation results of beam spots generated on the detection surface by the configurations of comparative examples 1 to 3, respectively, in accordance with Modification Example 11.
  • FIGS. 23A to 23C are diagrams showing simulation results of beam spots generated on the detection surface by the configurations of Examples 1 to 3, respectively, in Modification Example 11.
  • FIG. 24 is a graph showing a simulation result according to the eleventh modification.
  • Fig. 25(a) is a diagram showing a specific region and a method of arranging ribs according to Modification Example 1.
  • Fig. 25(b) is a diagram showing a region where curved ribs are arranged and a method of arranging the ribs according to a reference example.
  • each figure is labeled with mutually orthogonal X, Y, and Z axes.
  • the Z-axis direction is the up-down direction of the optical reflecting element 100
  • the X-axis and Y-axis directions are the long-side and short-side directions of the optical reflecting element 100, respectively.
  • the positive Z-axis direction is the upward direction of the optical reflecting element 100.
  • FIG. 1 is a plan view showing the configuration of the optical reflecting element 100
  • FIG. 2 is a cross-sectional view of the optical reflecting element 100 when the optical reflecting element 100 is cut at the position of the rotation axis R0 in FIG. 1 along a plane parallel to the X-Z plane.
  • the optical reflecting element 100 is configured as a meandering MEMS mirror.
  • the optical reflecting element 100 is not limited to a meandering MEMS mirror, and may have other configurations as long as the movable part 103 rotates about the rotation axis R0.
  • the optical reflecting element 100 includes a support portion 101, a pair of drive portions 102, and a movable portion 103.
  • the support part 101, the pair of drive parts 102, and the movable part 103 have a common silicon substrate 121 made of silicon.
  • the support part 101, the pair of drive parts 102, and the movable part 103 are connected by the silicon substrate 121.
  • the support part 101 is constructed by laminating a silicon substrate 122 made of silicon on the lower surface of the silicon substrate 121.
  • a silicon oxide film is interposed between the silicon substrate 121 and the silicon substrate 122.
  • the rigidity of the support part 101 is increased by having two silicon substrates 121, 122.
  • the support portion 101 is a frame-shaped member that has a rectangular outline in a plan view.
  • the driving unit 102 includes a substrate 110 and four piezoelectric actuators 111 formed on the upper surface of the substrate 110.
  • the substrate 110 has a meandering shape that snakes in a direction perpendicular to the rotation axis R0.
  • the thickness of the substrate 110 is constant.
  • the substrate 110 is a part of the silicon substrate 121 described above.
  • the four piezoelectric actuators 111 are arranged on the upper surface of the four regions 110a of the substrate 110, which extend in a direction perpendicular to the rotation axis R0 (the Y-axis direction).
  • the piezoelectric actuators 111 are configured by sandwiching a piezoelectric body of a certain thickness between an upper electrode and a lower electrode.
  • the piezoelectric body is made of, for example, PZT (lead zirconate titanate).
  • the upper and lower electrodes are made of, for example, platinum.
  • a voltage drive signal
  • the piezoelectric actuator 111 expands and contracts. This causes the substrate 110 to bend, generating a drive force for driving the movable part 103.
  • the movable part 103 is supported by a pair of drive parts 102.
  • the movable part 103 is part of the silicon substrate 121 described above.
  • the movable part 103 is circular.
  • the shape of the movable part 103 in a plan view may be another shape, such as a square.
  • the thickness of the movable part 103 is the same as the thickness of the silicon substrate 121 in FIG. 2.
  • the movable part 103 has a flat plate shape with the upper surface 103a and the lower surface 103b parallel to the XY plane.
  • a mirror M1 is formed on the upper surface 103a of the movable part 103.
  • the mirror M1 is formed on the entire upper surface 103a of the movable part 103.
  • Mirror M1 is formed by laminating an optical reflective film made of platinum, silver, or an alloy thereof onto upper surface 103a.
  • Mirror M1 may be formed of an optical multilayer film made of these materials.
  • mirror M1 may be formed of a dielectric material.
  • a reflective surface M1a is disposed on upper surface 103a of movable part 103. If upper surface 103a of movable part 103 has a high reflectivity, mirror M1 may be omitted and upper surface 103a of movable part 103 may be used as the reflective surface.
  • the reflecting surface M1a is irradiated with light whose intensity decreases with increasing distance from the central axis C0 (see Figures 5 and 6).
  • the intensity of this light has a Gaussian distribution.
  • the intensity of the light irradiated to the reflecting surface M1a has a similar Gaussian distribution all around the central axis C0.
  • Such a light intensity distribution can be achieved, for example, by using a vertical cavity surface emitting laser (VCSEL) as the light source.
  • VCSEL vertical cavity surface emitting laser
  • ribs 131a and 131b are formed on the lower surface 103b of the movable part 103.
  • the ribs 131a and 131b are made of silicon, similar to the silicon substrate 122.
  • Each of the ribs 131a and 131b is arranged in a circular ring shape.
  • Each of the ribs 131a and 131b has a wall shape with a substantially constant width and height.
  • Figure 3 is a diagram showing a schematic structure of the lower surface 103b of the movable part 103.
  • two ribs 131a, 131b having a circular shape in a planar view are arranged on the lower surface 103b of the movable part 103.
  • the ribs 131a, 131b are arranged concentrically with the center C1 of the lower surface 103b of the movable part 103.
  • the rib 131a is included in a specific area CA1 set near the center of the lower surface 103b.
  • the other ribs 131b are arranged along the outer periphery of the lower surface 103b.
  • the outer diameter D11 of the rib 131a is smaller than the diameter of the specific area CA1
  • the outer diameter D12 of the other ribs 131b is equal to the diameter of the movable part 103.
  • the width and height of the ribs 131a, 131b are the same.
  • the specific area CA1 where the rib 131a is arranged is an area corresponding to the vicinity of the center of the light irradiation area on the reflection surface M1a. In this embodiment, since the light irradiation area is circular, the specific area CA1 is also circular. The center of the specific area CA1 coincides with the center C1 of the lower surface 103b.
  • the specific area CA1 may have the same size as the area where the intensity of the light irradiated to the reflection surface M1a is half or more of the peak intensity.
  • the specific area CA1 may have a size equal to or larger than the size of the area where the intensity of the light irradiated to the reflection surface M1a is half or more of the peak intensity, and the specific area CA1 may have a size equal to or smaller than the size of the area where the intensity of the light irradiated to the reflection surface M1a is 1/e 2 (e is Napier's constant) of the peak intensity or more.
  • the optical reflecting element 100 To manufacture the optical reflecting element 100, a structure in which silicon substrates 121, 122 of a fixed thickness are stacked is used. The outline of this structure in a plan view is the same as the outline of the optical reflecting element 100 in FIG. 1. In addition, a layered structure of piezoelectric actuators 111 is uniformly stacked on the upper surface of this structure.
  • the silicon substrate 122 on the lower surface side is removed by etching this structure.
  • the silicon substrate 122 in the areas corresponding to the support portion 101 and the ribs 131a, 131b is left behind without being removed.
  • the ribs 131a, 131b are formed on the lower surface 103b of the movable portion 103.
  • the thickness of the support portion 101 is ensured by the silicon substrate 122 remaining on the support portion 101.
  • the layer structure of the piezoelectric actuator 111 is removed by etching from the top surface of this layer structure, leaving only the region of the piezoelectric actuator 111.
  • the mirror M1 is vapor-deposited in the region of the mirror M1.
  • the silicon substrates 121 and 122 are removed by etching in the regions other than the support portion 101, the pair of drive portions 102, and the movable portion 103. This completes the manufacture of the optical reflecting element 100 having the shape shown in Figures 1 and 2.
  • FIG. 4 is a plan view showing the configuration of the optical deflector 10.
  • FIG. 5 is a diagram showing the configuration of the optical scanning device 20.
  • FIG. 5 shows a cross-sectional view of the optical deflector 10 of FIG. 4 cut by a plane parallel to the YZ plane at the A-A position.
  • FIG. 5 shows a cross-sectional view of the optical deflector 10 when the movable part 103 is in a neutral position (a position when in a non-operating state).
  • FIG. 5 also shows the outer edge of the light L1 with a dashed line, and the central axis C0 of the light L1 (the optical axis of the optical system 300) with a dashed line.
  • the optical reflecting element 100 is mounted on a frame member 200.
  • the frame member 200 has a rectangular shape that is long in the X-axis direction in a plan view, and has a rectangular recess 201 into which the optical reflecting element 100 fits.
  • the frame member 200 has a constant thickness, and the recess 201 has a constant depth.
  • the recess 201 has a rectangular opening 202 that surrounds the drive unit 102 and movable unit 103 of the optical reflecting element 100 in a plan view.
  • the optical reflecting element 100 is mounted in the recess 201 with an adhesive or the like.
  • an optical system 300 for irradiating light L1 onto the reflecting surface M1a is disposed above the frame member 200.
  • the optical system 300 includes a light source 301, a collimator lens 302, a polarizing beam splitter 303 (hereinafter referred to as "PBS 303"), and a quarter-wave plate 304.
  • PBS 303 polarizing beam splitter 303
  • Light source 301 is the above-mentioned vertical cavity surface emitting laser light source (VCSEL), and emits laser light (light L1) of a predetermined wavelength in the positive direction of the Y axis.
  • Light source 301 is arranged so that it is S-polarized with respect to PBS 303.
  • Light source 301 emits light L1 at the same radiation angle over the entire circumference. Therefore, the cross-sectional shape of light L1 emitted from light source 301 is circular.
  • the collimator lens 302 collimates the light L1 emitted from the light source 301 and makes it incident on the PBS 303.
  • the PBS 303 has a cubic shape and has a polarization separation film 303a inside. Since the light L1 is incident on the polarization separation film 303a as S-polarized light, it is reflected by the polarization separation film 303a in the negative direction of the Z axis.
  • the quarter-wave plate 304 converts the light L1 incident from the PBS 303 side into circularly polarized light. The light L1 transmitted through the quarter-wave plate 304 is incident on the reflecting surface M1a of the optical reflecting element 100.
  • Light L1 reflected in the positive direction of the Z axis by reflecting surface M1a passes through quarter-wave plate 304 again, where it is converted to a polarization direction that becomes P-polarized with respect to polarization separation film 303a.
  • light L1 passes through polarization separation film 303a and is emitted from PBS 303 in the positive direction of the Z axis.
  • movable part 103 and mirror M1 rotate about rotation axis R0 from the neutral position shown in FIG. 5, the direction of light L1 emitted from PBS 303 rotates in the Y axis direction.
  • light L1 is scanned in the Y axis direction in a specified target area.
  • FIG. 6 is a diagram showing a schematic diagram of an irradiation area E1 of light L1 on the reflecting surface M1a and the light intensity distribution in the irradiation area E1.
  • Figure 6 shows the irradiation area E1 when the movable part 103 is in the neutral position.
  • the diameter D0 of the irradiation area E1 of the light L1 is set to be slightly smaller than the diameter of the reflecting surface M1a.
  • the central axis C0 of the light L1 (the center of the irradiation area E1) coincides with the center of the reflecting surface M1a.
  • the central axis C0 of the light L1 when it enters the reflecting surface M1a is parallel to the Z axis.
  • the upper side of Figure 6 shows the intensity distribution of light L1 in a direction parallel to the rotation axis R0 (X-axis direction), and the right side of Figure 6 shows the intensity distribution of light L1 in a direction perpendicular to the rotation axis R0 (Y-axis direction).
  • the intensity distribution of light L1 has a similar Gaussian distribution in both the direction parallel to the rotation axis R0 (X-axis direction) and the direction perpendicular to the rotation axis R0 (Y-axis direction).
  • the intensity distribution of light L1 in other directions is also similar to the intensity distribution shown in Figure 6.
  • the intensity distribution of light L1 in the irradiation area E1 has a similar Gaussian distribution over the entire circumference.
  • the region E1a where the intensity of the light L1 irradiated to the reflecting surface M1a is equal to or greater than 1/ e2 of the peak intensity P is a circular region having its center at the center of the irradiation region E1 and the reflecting surface M1a.
  • the region E1b where the intensity of the light L1 irradiated to the reflecting surface M1a is equal to or greater than half the peak intensity P is a circular region having its center at the center of the irradiation region E1 and the reflecting surface M1a.
  • the specific region CA1 shown in Fig. 3 may have the same size as the region E1b shown in Fig. 6, or may have a size equal to or greater than the size of the region E1b and equal to or less than the size of the region E1a.
  • the movable part 103 may bend (dynamic bend) due to the inertial force generated during rotation. Furthermore, as described above, when the mirror M1 is formed on the upper surface 103a of the movable part 103, the difference between the residual stress of the mirror M1 and the residual stress of the movable part 103 may cause bending (static bending) in the mirror M1 and the movable part 103. These bendings can be suppressed by forming ribs on the lower surface 103b of the movable part 103 to increase the strength (rigidity) of the movable part 103.
  • the formation of the ribs affects the flatness of the upper surface of the movable part 103, causing diffraction of the light L1 reflected by the reflecting surface M1a.
  • the light L1 reflected by the reflecting surface M1a contains not only the original reflected light that is not diffracted, but also unnecessary diffracted light that becomes noise in the optical scanning.
  • the inventors have discovered a relationship between the configuration of the ribs formed on the lower surface 103b of the movable part 103 and the diffracted light that occurs in the light L1 reflected by the reflecting surface M1a. According to this finding, by configuring the ribs 131a, 131b as described above, the movable part 103 can be reinforced and the influence of the diffracted light on the scanning of the light L1 can be effectively suppressed.
  • the above relationship discovered by the inventors is explained, and a preferred configuration of the ribs formed on the lower surface 103b of the movable part 103 is explained.
  • FIG. 7(a) is a diagram showing a schematic diagram of the configuration of the rib 132 in Comparative Example 1.
  • each intersecting ribs 132 is arranged on the lower surface 103b of the movable part 103.
  • the four ribs 132 extend linearly.
  • Two ribs 132 extend parallel to the X-axis, and the remaining two ribs 132 extend in the Y-axis direction.
  • the ribs 132 adjacent to each other in the X-axis direction are arranged symmetrically about the X-axis on the lower surface 103b, and the ribs 132 adjacent to each other in the Y-axis direction are arranged symmetrically about the Y-axis on the lower surface 103b.
  • the distance between adjacent ribs 132 in the X-axis direction is the same as the distance between adjacent ribs 132 in the Y-axis direction.
  • the inventors performed a simulation to determine the diffracted light that occurs in the light L1 reflected by the reflecting surface M1a when the rib 132 is configured as in Comparative Example 1.
  • the irradiation area E1 of the light L1 was the entire reflecting surface M1a.
  • the intensity distribution of the light L1 was set to a Gaussian distribution, as in FIG. 6.
  • the reflecting surface M1a was set to a neutral position, as in FIG. 5. It was also assumed that the light L1 reflected by the reflecting surface M1a was focused on the detection surface by an ideal lens.
  • the height and width of the change in shape that occurred on the reflecting surface M1a based on the ribs 132 (hereinafter referred to as the derived ribs) were set to 100 nm and 50 ⁇ m, respectively.
  • the diameter of the reflecting surface M1a was set to 1.4 mm, and the spacing between adjacent ribs 132 (spacing between derived ribs) was set to 0.4 mm.
  • Figure 7(b) shows the simulation results for Comparative Example 1 under the above conditions.
  • FIG. 7(b) shows the beam spot of light L1 on the detection surface. As shown in FIG. 7(b), in the configuration of the rib 132 in Comparative Example 1, multiple beam spots B0, B1, and B2 were generated.
  • Beam spot B0 is a beam spot of light L1 (zeroth order light) focused on the detection surface substantially without being subjected to diffraction by the derived ribs of the reflecting surface M1a based on the four ribs 132.
  • the multiple beam spots B1 above and below beam spot B0 are beam spots of multiple orders of diffracted light generated when light L1 is diffracted by the derived ribs of the reflecting surface M1a based on the ribs 132 extending parallel to the rotation axis R0.
  • the multiple beam spots B2 on the left and right of beam spot B0 are beam spots of multiple orders of diffracted light generated when light L1 is diffracted by the derived ribs of the reflecting surface M1a based on the ribs 132 extending perpendicular to the rotation axis R0.
  • these beam spots B0, B1, and B2 move in the Y-axis direction in response to the rotation of the movable part 103. Because the intensity of the beam spots B1 and B2 based on the diffracted light is relatively high, these beam spots B1 and B2 become noise in the scanning of the original beam spot B0.
  • FIG. 8(a) is a diagram showing a schematic configuration of the rib 132 according to the first embodiment.
  • Example 1 only the inner rib 131a is arranged on the lower surface 103b of the movable part 103. In other words, the outer rib 131b is omitted from the configuration in FIG. 3. The diameter of the rib 131a is 0.5 mm.
  • the other simulation conditions are the same as those in Comparative Example 1.
  • Figure 8(b) shows the simulation results for Example 1 under the above conditions.
  • FIG. 8(b) shows the beam spot of light L1 on the detection surface.
  • FIG. 8(b) in the configuration of rib 131a according to Example 1, only beam spot B0 was generated.
  • the distribution of beam spots based on diffracted light was hardly generated on the detection surface, and beam spot B0 of light L1 (zeroth order light) that was condensed substantially without being subjected to the diffraction effect of this derived rib was generated on the detection surface.
  • the derived rib generated on the reflecting surface M1a also has a curved shape.
  • the diffracted light generated by this derived rib is dispersed according to the curved shape, so that beam spots B1 and B2 based on the diffracted light do not substantially occur on the detection surface as shown in FIG. 8(b).
  • the configuration of the rib 131a in Example 1 makes it possible to effectively suppress the influence of the diffracted light based on the rib 131a.
  • the inventors further examined how diffracted light occurs for various rib configurations.
  • FIG. 9(a) is a diagram showing a schematic diagram of the configuration of rib 133 in Comparative Example 2
  • FIG. 9(b) is a diagram showing the simulation results of the beam spot generated on the detection surface when rib 133 in Comparative Example 2 is arranged.
  • beam images B4 based on diffracted light were generated to the left and right of beam spot B0.
  • the intensity of beam image B4 is relatively high, so beam image B4 becomes noise in the scanning of the original beam spot B0.
  • FIG. 9(c) is a diagram showing a schematic diagram of the configuration of rib 134 in Comparative Example 3
  • FIG. 9(d) is a diagram showing the simulation results of the beam spot generated on the detection surface when rib 134 in Comparative Example 3 is arranged.
  • FIG. 10(a) is a diagram showing a schematic diagram of the configuration of rib 131a1 according to Example 2
  • FIG. 10(b) is a diagram showing the results of a simulation of the beam spot generated on the detection surface when rib 131a1 according to Example 2 is arranged.
  • the shape of the rib 131a1 is an ellipse.
  • the center of the ellipse coincides with the center of the lower surface 103b.
  • the derived rib generated on the reflecting surface M1a by the rib 131a1 also has a similar elliptical shape.
  • Example 2 the long diameter D21 of the rib 131a1 (derived rib) was set to the same as the diameter of the rib 131a in Example 1.
  • the short diameter D22 of the rib 131a1 (derived rib) was set to 0.25 mm.
  • the other simulation conditions were the same as those in Comparative Example 1.
  • Example 2 As shown in FIG. 10(b), in the configuration of Example 2, almost no image based on diffracted light was generated around beam spot B0, and essentially only beam spot B0 was generated. With the configuration of rib 131a1 in Example 2, the effect of diffracted light based on rib 131a1 could be effectively suppressed, as in Example 1.
  • FIG. 10(c) is a diagram showing a schematic configuration of the rib 131a2 according to the third embodiment
  • FIG. 10(d) is a diagram showing the results of a simulation of the beam spot that appears on the detection surface when the rib 131a2 according to the third embodiment is arranged.
  • the ribs 131a2 are arranged along a curved amplitude waveform.
  • the center of the area surrounding the amplitude waveform coincides with the center of the lower surface 103.
  • the derived ribs generated on the reflecting surface M1a by the ribs 131a2 also have a shape that follows the same amplitude waveform.
  • Example 2 In the simulation of Example 2, the width D31 of the rib 131a2 (derived rib) was set to 0.7 mm, and the amplitude D32 of the rib 131a2 (derived rib) was set to 0.25 mm.
  • the other simulation conditions were the same as those of Comparative Example 1.
  • Example 3 As shown in FIG. 10(d), in the configuration of Example 3, almost no image based on diffracted light was generated around beam spot B0, and essentially only beam spot B0 was generated. With the configuration of rib 131a2 in Example 3, the influence of diffracted light based on rib 131a2 could be effectively suppressed, as in Example 1.
  • ribs that are curved in plan view in a specific area CA1 of the lower surface 103b that corresponds to the vicinity of the center of the reflecting surface M1a where the intensity of the irradiated light L1 is high. This makes it possible to prevent the generation of high-intensity diffracted light and to prevent the diffracted light from affecting the scanning of the light L1.
  • the region outside the specific region CA1 corresponds to the region at the base of the Gaussian distribution shown in Figure 6, and therefore the intensity of the light L1 irradiated to the reflecting surface M1a is low.
  • the intensity of the diffracted light diffracted by the derived rib based on this rib is significantly lower than the intensity of the original light L1 (zeroth-order diffracted light). Therefore, the effect of this diffracted light on the scanning of light L1 is significantly reduced.
  • linear ribs may be arranged in a planar view in the area outside the specific area CA1. This reinforces the outer area and further suppresses deflection of the movable part 103 and the reflecting surface M1a. However, if it is desired to more thoroughly suppress the effect of diffracted light on the scanning of the light L1, it is preferable not to arrange linear ribs in the area outside the specific area CA1.
  • the irradiation area E1 deforms from a perfect circle in the tilting direction, and accordingly, the area near the center of the irradiation area E1, where the light intensity is high, also deforms from a perfect circle.
  • the portion that protrudes from the area near the center (perfect circle) at the neutral position is small compared to the entire area (perfect circle), and the intensity of the protruding portion is considerably lower than the peak intensity.
  • a specific area CA1 may be set on the lower surface 103b corresponding to the area obtained by combining the range in which the area near the center of the irradiation area E1 may deviate from a perfect circle during actual operation with the range of this perfect circle, and essentially only curved ribs may be placed in this specific area CA1. This also applies to the cases in which the intensity distribution of the irradiation area E1 is not uniform, as shown in Modifications 2 and 3 below.
  • the optical reflecting element 100 includes a flat movable part 103 that rotates about a rotation axis R0, a reflecting surface M1a disposed on the upper surface 103a of the movable part 103, and at least one rib 131a, 131b disposed on the lower surface 103b of the movable part 103.
  • light L1 the intensity of which decreases with distance from the central axis C0, is irradiated onto the reflecting surface M1a.
  • the central axis C0 of the light L1 substantially coincides with the center of the reflecting surface M1a.
  • the ribs 131a, 131a1, 131a2 in a specific area CA1 of the lower surface 103b corresponding to the vicinity of the center of the irradiation area E1 of the light L1 on the reflecting surface M1a have a curved shape in a plan view.
  • ribs 131a, 131b, 131a1, and 131a2 are arranged on the lower surface 103b of the movable part 103, so that the movable part 103 is reinforced by these ribs. This makes it possible to suppress the occurrence of bending (dynamic bending, static bending) in the movable part 103 and the reflecting surface M1a arranged on its upper surface 103a.
  • curved ribs 131a, 131a1, and 131a2 are arranged in a specific area CA1 on the lower surface of the movable part 103.
  • the diffracted light generated by the shape change (derived ribs) of the reflecting surface M1a based on these ribs is dispersed, and as shown in Figures 8(b), 10(b), and 10(d), peaks are unlikely to occur in the diffracted light. This effectively suppresses the diffracted light of the light L1 near the center, which has a high intensity, from affecting the light scanning.
  • the ribs 131a, 131a1 in the specific area CA1 are arranged in a ring shape in a plan view.
  • the strength of the movable part 103 near the center can be stably increased by the ribs 131a and 131a1. Therefore, deflection near the center of the reflecting surface M1a, where the intensity of the irradiated light is high, can be effectively suppressed.
  • the ribs 131a in the specific area CA1 are arranged along a perfect circle.
  • the ribs 131a1 in the specific area CA1 are arranged along an ellipse.
  • the strength of the movable part 103 near the center can be stably increased by the rib 131a1. Therefore, deflection near the center of the reflecting surface M1a, where the intensity of the irradiated light is high, can be effectively suppressed.
  • the ribs 131a2 in the specific area CA1 are arranged along a curved amplitude waveform.
  • curved ribs can be placed in the area of the movable part 103 where the intensity of the irradiated light is high. This increases the strength of the area of the movable part where the intensity of the irradiated light is high, and suppresses the deflection of the reflective surface in this area.
  • another rib 131b is disposed outside the specific area CA1.
  • the other ribs 131b can increase the strength of the movable part 103 on the outside from near the center. This makes it possible to expand the range in which deflection of the reflecting surface M1a can be suppressed.
  • the other ribs 131b are arranged in a ring shape in a plan view.
  • the other ribs 131b can increase the strength of the movable part 103 near its outer periphery. This can suppress the deflection of the reflecting surface M1a near the outer periphery of the movable part 103.
  • the specific area CA1 may have substantially the same size as the area E1b where the intensity of the light L1 irradiated to the reflecting surface M1a is equal to or greater than half the peak intensity.
  • the specific area CA1 may have a size that is substantially greater than the size of area E1b where the intensity of light L1 irradiated to the reflecting surface M1a is equal to or greater than half the peak intensity, and less than the size of area E1a where the intensity of light L1 irradiated to the reflecting surface M1a is equal to or greater than 1/ e2 (e is Napier's constant) of the peak intensity.
  • a mirror M1 optical reflection film is formed on the upper surface 103a of the movable part 103 to form a reflection surface M1a.
  • the reflectance of the reflecting surface M1a can be increased and the surface roughness can be suppressed compared to when the upper surface 103a of the movable part 103 is used as a reflecting surface as is. Therefore, scanning of the light L1 can be performed with high precision.
  • Fig. 11 is a diagram showing a schematic diagram of a method for arranging ribs according to Modification Example 1.
  • Fig. 11 shows a plan view of the movable part 103 as viewed from the bottom side (Z-axis negative side).
  • two ribs 131c are added compared to the embodiment in FIG. 3.
  • the two ribs 131c are arranged along the rotation axis R0 and connect the ribs 131a and 131b.
  • the width and height of the rib 131c are the same as those of the ribs 131a and 131b.
  • the outer diameter of the inner rib 131a is approximately the same as the diameter of the specific area CA1.
  • the two ribs 131c suppress the deflection (particularly static deflection) of the area of the movable part 103 between the ribs 131a and 131b.
  • the irradiation area E1 of the light L1 on the reflecting surface M1a includes a derived rib corresponding to the rib 131c, so that this derived rib can cause a peak in the diffracted light.
  • the inventors conducted a simulation to verify the relationship between the diameter of rib 131a and the length of rib 131c and the intensity of diffracted light.
  • the outer rib 131b was omitted and the outer diameter D of the inner rib 131a was changed. As the outer diameter D increased, the length of the rib 131c was decreased. As in the simulation in the above embodiment, the light L1 was irradiated onto the entire reflecting surface M1a. The height and width of the ribs 131a and 131c were set in the same way as in the simulation in the above embodiment. The rest of the simulation was the same as in the simulation in the above embodiment.
  • a reference line L0 was set on the detection surface that passed through the center of the beam spot and was parallel to the diffraction direction, and the intensity of the diffracted light distributed on the reference line L0 was obtained. More specifically, in a range W1 other than the range W0 of the beam spot B0 that is not affected by diffraction, a value corresponding to the sum of the intensities of the diffracted light distributed on the reference line L0 was obtained as a parameter value indicating the intensity of the diffracted light.
  • the total value obtained by integrating, for the range W1, the ratio of the intensity of the diffracted light at each position on the reference line L0 to the peak value of the intensity of the light L1 reflected by the reflecting surface M1a when no ribs are provided on the lower surface 103b of the movable part 103 was obtained.
  • the range W1 was set to the range in which diffracted light is substantially generated.
  • Figure 13 is a graph showing the simulation results.
  • the horizontal axis is the diameter of the region between the two ribs 131c, which corresponds to the outer diameter D in FIG. 12.
  • the vertical axis is the parameter value indicating the intensity of the diffracted light described with reference to FIG. 12(b).
  • D1 indicated in the graph is the diameter of the region (corresponding to region E1b in FIG. 6) where the intensity of light L1 irradiated on the reflecting surface M1a is half the peak intensity
  • D2 is the diameter of the region (corresponding to region E1a in FIG. 6) where the intensity of light L1 irradiated on the reflecting surface M1a is 1/ e2 or more of the peak intensity
  • D3 is half the diameter of the irradiation region E1 of light L1 on the reflecting surface M1a.
  • the parameter value indicating the intensity of the diffracted light decreases as the diameter (outer diameter D) of the region between ribs 131c increases, and after this diameter (outer diameter D) reaches diameter D1 of region E1b, the tendency for the parameter value to decrease becomes gentler. Furthermore, after this diameter (outer diameter D) reaches diameter D2 of region E1a, the tendency for the parameter value to decrease becomes even gentler, and after this diameter (outer diameter D) reaches diameter D3b, the parameter value indicating the intensity of the diffracted light remains near zero.
  • the two straight ribs 131c are not arranged in a range of diameters smaller than the diameter D1 of the region (region E1b in Figure 6) where the intensity of the light L1 irradiated to the reflecting surface M1a is half the peak intensity or more, and it is even more preferable that the two straight ribs 131c are not arranged in a range of diameters smaller than the diameter D2 of the region (region E1a in Figure 6) where the intensity of the light L1 irradiated to the reflecting surface M1a is 1/ e2 or more of the peak intensity.
  • the specific area CA1 where the curved rib is arranged has substantially the same size as the area (area E1b in FIG. 6) where the intensity of the light L1 irradiated to the reflecting surface M1a is half the peak intensity or more.
  • the specific area CA1 where the curved rib is arranged has a size substantially equal to or larger than the area (area E1b in FIG. 6) where the intensity of the light L1 irradiated to the reflecting surface M1a is half the peak intensity or more, and is smaller than the area where the intensity of the light L1 irradiated to the reflecting surface M1a is 1/ e2 or more of the peak intensity.
  • the other ribs 131c can increase the strength of the movable part 103 up to near the outer periphery, and the range in which deflection of the reflecting surface M1a can be suppressed can be expanded up to near the outer periphery.
  • the direction in which the other rib 131c extends is parallel to the rotation axis R0.
  • This configuration makes it possible to prevent the moment of inertia of the movable part 103 rotating about the rotation axis R0 from increasing due to the rib 131c. This allows the movable part 103 to rotate smoothly.
  • the other ribs 131c are arranged along a straight line.
  • This configuration allows the other ribs 131c to be formed smoothly.
  • the increase in the moment of inertia caused by the other ribs 131c can be kept to a minimum.
  • the other ribs 131c are parallel to the rotation axis R0 in a plan view, but as shown in FIGS. 14(a) and (b), the other ribs 131c may be slightly tilted (for example, about 5°) with respect to the rotation axis R0 in a plan view. In other words, the other ribs 131c only need to be substantially parallel to the rotation axis R0 in a plan view. This also effectively prevents the moment of inertia of the movable part 103 rotating about the rotation axis R0 from increasing beyond the ribs 131c.
  • 15(a) and 15(b) are diagrams each showing a schematic diagram of a rib arrangement according to Modification Example 2 and Modification Example 3.
  • Fig. 15(a) and (b) show plan views of the movable part 103 as viewed from the bottom side (Z-axis negative side).
  • the irradiation area E1 when the movable part 103 is in the neutral position is changed to an ellipse. Therefore, the specific area CA1 is also elliptical in shape, and the rib 131a arranged within the area CA1 is also elliptical in shape.
  • the other configurations are the same as modified example 1.
  • FIG. 16 is a schematic diagram showing the irradiation area E1 of the light L1 on the reflecting surface M1a and the light intensity distribution in the irradiation area E1 in the second modified example.
  • FIG. 16 shows the irradiation area E1 when the movable part 103 is in the neutral position.
  • the minor axis of the ellipse that defines the irradiation area E1 is parallel to the rotation axis R0, and the major axis of the ellipse is perpendicular to the rotation axis R0.
  • the major axis is equal to the diameter of FIG. 6.
  • Such an illumination area E1 occurs, for example, when the light source 301 in FIG. 5 is an edge-emitting laser diode.
  • the major axis of the ellipse corresponds to the fast axis of the laser diode, and the minor axis of the ellipse corresponds to the slow axis of the laser diode.
  • the specific area CA1 in which the curved rib is arranged should have substantially the same size as the area E1b in which the intensity of the light L1 irradiated to the reflecting surface M1a is half the peak intensity or more.
  • the specific area CA1 in which the curved rib is arranged should have a size substantially equal to or larger than the area E1b in which the intensity of the light L1 irradiated to the reflecting surface M1a is half the peak intensity or more, and be smaller than the area in which the intensity of the light L1 irradiated to the reflecting surface M1a is 1/ e2 or more of the peak intensity.
  • the rib 131a arranged in the specific area CA1 can be set to, for example, an elliptical shape as shown in FIG. 15(a). This allows the rib 131a to be smoothly arranged in the elliptical irradiation area E1.
  • the rib 131a arranged in the specific area CA1 can be set to, for example, an elliptical shape as shown in FIG. 15(b). This allows the rib 131a to be smoothly arranged in the elliptical irradiation area E1.
  • the specific area CA1 has substantially the same size as the area E1b where the intensity of the light L1 irradiated to the reflecting surface M1a is equal to or greater than half the peak intensity.
  • the specific area CA1 where the curved rib is arranged has a size substantially equal to or greater than the size of the area E1b where the intensity of the light L1 irradiated to the reflecting surface M1a is equal to or greater than half the peak intensity, and less than the size of the area where the intensity of the light L1 irradiated to the reflecting surface M1a is equal to or greater than 1/ e2 of the peak intensity.
  • the specific area CA1 does not necessarily have to be an ellipse.
  • the specific area CA1 may be a circle whose diameter is the major axis of area E1b, or a circle whose diameter is the major axis of area E1a.
  • the specific area CA1 may be a circle whose diameter is the minor axis of area E1a, or a circle whose diameter is the length between the major axis of area E1a and the major axis of area E1b.
  • Figures 17(a) and 17(b) are diagrams that typically show rib arrangement methods according to Modifications 4 and 5, respectively.
  • Figures 18(a) and 18(b) are diagrams that typically show rib arrangement methods according to Modifications 6 and 7, respectively.
  • Figures 17(a), (b) and 18(a), (b) show plan views of the movable part 103 as viewed from the bottom side (Z-axis negative side).
  • the shape of the curved ribs arranged in specific area CA1 is not limited to a circle or an ellipse, and may be, for example, a shape as shown in modification example 4 of FIG. 17(a), or a wave shape as shown in modifications examples 6 and 7 of FIG. 18(a) and (b).
  • the diameter of specific area CA1 by setting the diameter of specific area CA1 to be close to diameter D1 in FIG. 13 or in the range of diameters D1 to D2, the influence of diffracted light due to linear ribs 131c can be effectively suppressed, as in the verification results of FIG. 13.
  • the ribs arranged in the specific area CA1 do not necessarily have to be continuously connected; for example, as shown in FIG. 17(b), they may be arranged along a circular shape with some parts interrupted.
  • the shape of the ribs arranged in the specific area CA1 is another shape such as an ellipse or a wave shape, the ribs may also be partially interrupted. This also allows the strength of the specific area CA1 to be increased by these ribs.
  • 19(a) and 19(b) are diagrams each showing a schematic diagram of a rib arrangement according to Modification Example 8 and Modification Example 9.
  • Fig. 19(a) and (b) show plan views of the movable part 103 as viewed from the bottom side (Z-axis negative side).
  • the other ribs 131c arranged outside the specific area CA1 do not necessarily have to be arranged along a straight line.
  • the other ribs 131c may be arranged along a curved amplitude waveform.
  • the diffracted light caused by the change in shape of the reflecting surface M1a due to the other ribs 131c is dispersed by the curved shape, making it difficult for peaks to occur in the diffracted light due to the other ribs 131c. This makes it possible to further suppress the effects of the diffracted light due to the other ribs.
  • the direction in which the other ribs 131c extend is substantially parallel to the rotation axis R0, as shown in FIG. 19(a). This makes it possible to prevent the moment of inertia of the movable part 103 rotating about the rotation axis R0 from increasing compared to the other ribs 131c. This allows the movable part 103 to rotate smoothly.
  • the ribs arranged in the specific region CA1 need only have a substantially curved shape, and the ribs arranged in the region CA1 may include a slight straight line portion.
  • the rib 131a arranged in the specific region CA1 may include a slight straight line portion P1.
  • the straight line portion included in the region CA1 is extremely small in this way, the diffracted light caused by this can be substantially ignored. Therefore, with this configuration, as with the above embodiment and each modification example, the effect of diffracted light on the scanning of light L1 can be effectively suppressed.
  • the height of the ribs 131a, 131b is constant in the width direction of the ribs (the Y-axis direction in FIG. 20(a)).
  • the height of the ribs 131a, 131b is not limited to this and may vary in the width direction of the ribs.
  • the height of ribs 131a, 131b may vary in the width direction of the ribs so that the lower surfaces of ribs 131a, 131b are curved in the width direction of the ribs.
  • the shape (derived rib) created on the reflecting surface M1a by the ribs 131a and 131b can be made to vary in the height direction, making diffraction less likely to occur due to this shape (derived rib). This makes it possible to suppress the effect of diffracted light by the ribs 131a and 131b on the scanning of the light L1.
  • This configuration may be similarly applied to ribs 131a1, 131a2, and other ribs 131c.
  • this configuration may be applied only to linear ribs that are likely to cause diffraction, or this configuration may be applied only to ribs located in specific area CA1 that corresponds to the area where high-intensity light is irradiated.
  • FIG. 21 is a schematic diagram showing the irradiation area E1 of the light L1 on the reflecting surface M1a and the light intensity distribution in the irradiation area E1 in Modification Example 11.
  • FIG. 21 shows the irradiation area E1 when the movable part 103 is in the neutral position.
  • the diameter D0 of the irradiation area E1 of the light L1 is set to be slightly smaller than the diameter of the reflecting surface M1a.
  • the central axis C0 of the light L1 (the center of the irradiation area E1) coincides with the center of the reflecting surface M1a.
  • Figure 21 shows the intensity distribution of light L1 in a direction parallel to the rotation axis R0 (X-axis direction), and the right side of Figure 21 shows the intensity distribution of light L1 in a direction perpendicular to the rotation axis R0 (Y-axis direction).
  • the intensity distribution of light L1 has two peak intensities near the central axis C0.
  • the positions of these peak intensities are aligned in a direction perpendicular to the rotation axis R0 (Y-axis direction).
  • the intensity distribution of light L1 has a Gaussian distribution in a direction parallel to the rotation axis R0 (X-axis direction). The intensity of light L1 decreases as it moves away from each peak intensity position.
  • Light L1 with such an intensity distribution is emitted, for example, from a multi-mode laser light source.
  • the region E1a where the intensity of the light L1 irradiated to the reflecting surface M1a is 1/ e2 or more of the peak intensity P has a shape of two overlapping circles each having a center at the position of the two peak intensities
  • the region E1b where the intensity of the light L1 is half the value of the peak intensity P or more also has a shape of two overlapping circles each having a center at the position of the two peak intensities.
  • the above-mentioned specific region CA1 may have substantially the same size as the region E1b, or may have a size substantially equal to or larger than the size of the region E1b and smaller than the size of the region E1a.
  • the specific region CA1 may be a circular or elliptical region inscribed with the region E1a or the region E1b in a plan view.
  • Figures 22(a) to (c) show simulation results of the beam spots generated on the detection surface by the configurations of comparative examples 1 to 3 in modification example 11.
  • Figures 22(a) to (c) show schematic diagrams of the arrangement of ribs 132, 133, and 134 in Comparative Examples 1 to 3.
  • the lower parts of Figures 22(a) to (c) show simulation results of the beam spots that are generated on the detection surface when the configurations of Comparative Examples 1 to 3 are used.
  • the simulation conditions are the same as those of Comparative Examples 1 to 3 in Figures 7(a), (b) and Figures 9(a) to (d), except that the intensity distribution of light L1 irradiated to the reflecting surface M1a is the intensity distribution in Figure 21.
  • Figures 23(a) to (c) show simulation results of the beam spots generated on the detection surface by the configurations of Examples 1 to 3 in Modification Example 11.
  • Figures 23(a) to (c) show schematic diagrams of the arrangement of ribs 131a, 131a1, and 131a2 in Examples 1 to 3.
  • the lower parts of Figures 23(a) to (c) show simulation results of the beam spots that are generated on the detection surface when the configurations of Examples 1 to 3 are used.
  • the simulation conditions are the same as those of Examples 1 to 3 in Figures 8(a), (b) and 10(a) to (d), except that the intensity distribution of light L1 irradiated to the reflecting surface M1a is the intensity distribution in Figure 21.
  • FIG. 24 is a graph showing the results of a simulation performed under the same conditions as in FIG. 13 to determine the intensity of diffracted light that occurs when light L1 having the intensity distribution in FIG. 21 is irradiated onto reflecting surface M1.
  • the simulation conditions are the same as those in FIG. 13, except that the intensity distribution of the irradiated light L1 is the intensity distribution in FIG. 21.
  • the vertical and horizontal axes in FIG. 24 are also the same as those in FIG. 13.
  • the diffracted light intensity decreases as the outer diameter D increases, and in the range in which the outer diameter D is from diameter D1' to diameter D2', the diffracted light intensity increases slightly as the outer diameter D increases. Then, when the outer diameter D becomes larger than diameter D2', the diffracted light intensity decreases as the outer diameter D increases.
  • diameter D1' corresponds to the width of the constricted portion of region E1a that is equal to or greater than 1/ e2 of the peak intensity P in the intensity distribution of Fig. 21, i.e., the width of region E1a in the X-axis direction at the position of rotation axis R0. Therefore, when the outer diameter D of the inner rib 131a becomes equal to or greater than diameter D1', the two outer ribs 131c in Fig. 12(a) no longer overlap region E1a, and the effects of diffraction by these ribs 131c are suppressed.
  • the inner rib 131a falls on the peak of the intensity distribution of light L1, and the intensity of the diffracted light based on the inner rib 131a increases. Therefore, in the range where the outer diameter D of the inner rib 131a is between diameter D1' and diameter D2', the intensity of the diffracted light increases slightly as the outer diameter D increases. Then, when the outer diameter D of the inner rib 131a exceeds diameter D2', the peak of the intensity distribution of light L1 is included inside the inner rib 131a. Therefore, in the range where the outer diameter D of the inner rib 131a exceeds diameter D2', the intensity of the diffracted light decreases as the outer diameter D increases.
  • specific area CA1 may be circular or elliptical.
  • specific area CA1 may be in the shape of an ellipse with its major axis aligned in the direction in which the peaks are lined up.
  • specific area CA1 may have a shape similar or nearly similar to area E1a.
  • the light L1 whose intensity decreases with increasing distance from the central axis, is irradiated onto the reflecting surface M1a, and the specific area CA1 is set as shown in Fig. 25(a).
  • the center C1 of the lower surface 103b and the center C2 of the irradiation area E1 are substantially coincident with each other in a plan view.
  • the area of the region CB1 in which the curved rib 131a is arranged may be set so that the area of the region CB1 is larger than the area of the lower surface 103b outside the region CB1.
  • the area of the region CB1 may be set so that the area of the region CB1 is larger than the area of the region corresponding to the irradiation region E1 outside the region CB1.
  • the proportion of the amount of light contained in the area of reflecting surface M1a corresponding to area CB1 out of the total amount of light irradiated to reflecting surface M1a can be increased, and the proportion of the amount of light that does not undergo diffraction can be increased. Therefore, the effect of diffracted light on the scanning of the light can be suppressed.
  • the optical system 300 in Fig. 5 is exemplified as an optical system that irradiates the reflecting surface M1a with light, but the configuration of the optical system is not limited to this.
  • the PBS 303 and the 1 ⁇ 4 wavelength plate 304 may be omitted from the optical system 300 in Fig. 5.
  • the light L1 is irradiated obliquely onto the reflecting surface M1a so that the central axis C0 is inclined by a predetermined angle with respect to the normal line of the reflecting surface M1a.
  • the irradiation area E1 of the reflecting surface M1a is not a perfect circle, but a curved ring shape that is long in the direction in which the central axis C0 is tilted.
  • the area CA1 near the center has a size substantially the same as the area in this irradiation area E1 where the light intensity is half or more of the peak intensity, or has a size substantially equal to or larger than the area where the light intensity irradiated to the reflecting surface is half or more of the peak intensity and smaller than the area where the light intensity irradiated to the reflecting surface is 1/ e2 (e is Napier's constant) of the peak intensity.
  • the direction in which the other ribs 131c extend is substantially parallel to the rotation axis R0, but the direction in which the other ribs 131c extend may be non-parallel to the rotation axis R0.
  • the central axis C0 of the light L1 substantially coincides with the center of the reflecting surface M1a (the center of the upper surface 103a of the movable part 103), but the central axis C0 of the light L1 may be offset from the center of the reflecting surface M1a (the center of the upper surface 103a of the movable part 103).
  • the central axis C0 of the light L1 is slightly offset from the center of the reflecting surface M1a (the center of the upper surface 103a of the movable part 103) in a direction parallel to the rotation axis R0, the scanning of the light L1 itself can be performed in the same way.
  • the height and width of the ribs arranged within the specific area CA1 are the same as the height and width of the ribs arranged outside this area CA1, but one or both of the heights and widths of these ribs may be different from each other.
  • a laser light source is used as the light source 301, but this is not limiting, and for example, a light emitting diode may be used as the light source 301.
  • the device to which the optical reflecting element 100 and the optical deflector 10 are applied is not particularly limited, and may be any device that requires a configuration for scanning light by rotating the reflecting surface M1a.
  • FIG. 1 A flat plate-shaped movable part that rotates about a rotation axis; A reflecting surface disposed on an upper surface of the movable portion; At least one rib disposed on a lower surface of the movable part, A light beam having an intensity decreasing with distance from the central axis is irradiated onto the reflecting surface, The rib in a specific region of the lower surface corresponding to the vicinity of the center of the light irradiation region on the reflecting surface has a substantially curved shape in a plan view.
  • An optical reflecting element characterized by:
  • ribs are placed on the underside of the movable part, reinforcing the movable part with the ribs. This makes it possible to prevent bending of the movable part and the reflective surface placed on its upper surface. Furthermore, ribs that are substantially curved are placed in specific areas on the underside of the movable part. As a result, diffracted light caused by changes in the shape of the reflective surface due to these ribs is dispersed, making it less likely that peaks will occur in the diffracted light. This makes it possible to effectively prevent the effect of diffraction by the ribs on light near the center, where the intensity of the irradiated light is high.
  • This technology allows the strength of the moving part near the center to be stably increased by the ribs. This effectively reduces deflection near the center of the reflective surface, where the intensity of the irradiated light is high.
  • optical reflecting element In the optical reflecting element according to any one of the first to fourth aspects, The ribs in the specific region are arranged along a curved amplitude waveform.
  • An optical reflecting element characterized by:
  • This technology allows curved ribs to be placed in areas of the moving part where the intensity of the irradiated light is high. This increases the strength of the areas of the moving part where the intensity of the irradiated light is high, and suppresses deflection of the reflective surface in these areas.
  • optical reflecting element In the optical reflecting element according to any one of the first to fifth aspects, The other ribs are arranged outside the specific region.
  • An optical reflecting element characterized by:
  • the strength of the movable parts on the outside can be increased by using other ribs, which makes it possible to expand the range in which deflection of the reflective surface can be suppressed.
  • optical reflecting element In the optical reflecting element according to the sixth aspect of the present invention, the other rib extends radially from the center of the lower surface.
  • An optical reflecting element characterized by:
  • the strength of the moving part can be increased up to the outer periphery by using other ribs, and the range in which deflection of the reflective surface can be suppressed can be expanded up to the outer periphery.
  • optical reflecting element In the optical reflecting element according to the seventh aspect of the present invention, The direction in which the other rib extends is substantially parallel to the pivot axis.
  • An optical reflecting element characterized by:
  • This technology makes it possible to prevent the moment of inertia of the movable part rotating about the rotation axis from increasing due to other ribs. This allows the movable part to rotate smoothly.
  • optical reflecting element In the optical reflecting element according to the seventh or eighth aspect of the present invention, The other ribs are arranged along a straight line.
  • An optical reflecting element characterized by:
  • This technology allows the other ribs to be formed smoothly. Also, if the other ribs are parallel to the rotation axis, the increase in the moment of inertia caused by the other ribs can be kept to a minimum.
  • optical reflecting element In the optical reflecting element according to the seventh or eighth aspect of the present invention, The other ribs are arranged along a curved amplitude waveform.
  • An optical reflecting element characterized by:
  • the diffracted light caused by changes in the shape of the reflective surface due to other ribs is dispersed, making it less likely that peaks will occur in the diffracted light due to other ribs. This makes it possible to suppress the effects of diffracted light due to other ribs.
  • optical reflecting element In the optical reflecting element according to the sixth aspect of the present invention, The other rib is arranged in an annular shape in a plan view.
  • An optical reflecting element characterized by:
  • the strength of the movable part near its outer periphery can be increased by using other ribs. This makes it possible to suppress deflection of the reflective surface near the outer periphery of the movable part.
  • the specific region has a size substantially the same as that of a region where the intensity of the light irradiated on the reflecting surface is equal to or greater than half of the peak intensity.
  • This technology can suppress the effect of diffraction by the ribs on light irradiated onto the reflecting surface that is within an intensity range of at least half the peak intensity. This effectively suppresses the effect of diffracted light on the scanning light.
  • the specific area has a size that is substantially equal to or larger than the size of an area where the intensity of the light irradiated onto the reflecting surface is equal to or larger than half the peak intensity, and is equal to or smaller than the size of an area where the intensity of the light irradiated onto the reflecting surface is equal to or larger than 1/ e2 (e is Napier's constant) of the peak intensity.
  • An optical reflecting element characterized by:
  • This technology can suppress the effect of diffraction by the ribs on light that is irradiated onto the reflecting surface and falls within a high-intensity range. This makes it possible to more effectively suppress the effect of diffracted light on the scanning light.
  • optical reflecting element In the optical reflecting element according to any one of the first to third aspects of the present invention, The height of the rib varies continuously in the width direction of the rib.
  • An optical reflecting element characterized by:
  • the shape created by the ribs on the reflective surface can be varied in the height direction, making diffraction less likely to occur. This makes it possible to suppress the effect of diffracted light on the scanning light.
  • the reflecting surface is disposed by forming an optical reflecting film on an upper surface of the movable portion.
  • An optical reflecting element characterized by:
  • This technology makes it possible to increase the reflectivity of the reflective surface and suppress surface roughness compared to when the upper surface of the movable part is used as the reflective surface itself. This allows for highly accurate light scanning.
  • a flat plate-shaped movable part that rotates about a rotation axis; A reflecting surface disposed on an upper surface of the movable portion; At least one rib disposed on a lower surface of the movable part, The reflecting surface is irradiated with light having a plurality of peak intensities near a central axis, the intensity of which decreases with distance from each of the peak intensities; The rib in a specific region of the lower surface corresponding to the vicinity of the center of the light irradiation region on the reflecting surface has a substantially curved shape in a plan view.
  • An optical reflecting element characterized by:
  • ribs are placed on the underside of the movable part, reinforcing the movable part with the ribs. This makes it possible to prevent bending of the movable part and the reflective surface placed on its upper surface. Furthermore, ribs that are substantially curved are placed in specific areas on the underside of the movable part. As a result, diffracted light caused by changes in the shape of the reflective surface due to these ribs is dispersed, making it less likely that peaks will occur in the diffracted light. This makes it possible to effectively prevent the effect of diffraction by the ribs on light near the center, where the intensity of the irradiated light is high.
  • a flat plate-shaped movable part that rotates about a rotation axis; A reflecting surface disposed on an upper surface of the movable portion; A first rib is disposed on a lower surface of the movable portion and surrounds a center of the lower surface; a second rib disposed on the lower surface outside the first rib and extending substantially parallel to the pivot axis; The first rib has a substantially curved shape in a plan view, No other ribs are provided on the inside of the first rib.
  • An optical reflecting element characterized by:
  • the first rib and the second rib are arranged on the lower surface of the movable part, and the movable part is reinforced by these ribs.
  • the second rib is arranged substantially parallel to the rotation axis, the second rib can suppress the moment of inertia of the movable part rotating about the rotation axis from increasing. This allows the movable part to rotate smoothly.
  • substantially only the first rib which has a curved shape, is arranged.
  • the shape change of the reflective surface due to the first rib also becomes a shape that substantially surrounds the center with a curve. Therefore, diffraction does not occur inside the shape change of the reflective surface, and the diffracted light generated by this shape change is dispersed and is less likely to produce a peak. This makes it possible to effectively suppress the effect of diffraction by the first rib on the light near the center where the intensity of the irradiated light is high.
  • Optical reflecting element 103 Movable part 103a Upper surface 103b Lower surface 131a, 131b, 131c, 131a1, 131a2 Rib CA1 Specific area E1 Irradiation area E1a Area (area with an intensity of 1/ e2 or more of the peak intensity) E1b region (region with intensity equal to or greater than half the peak intensity) L1 light M1a reflective surface

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Facsimile Scanning Arrangements (AREA)

Abstract

L'invention concerne un élément de réflexion optique (100) comprenant : une partie mobile (103) ayant une forme de plaque plate qui tourne autour d'un axe de rotation (R0) ; une surface de réflexion (M1a) qui est disposée sur une surface supérieure (103a) de la partie mobile (103) ; et au moins une nervure (131a, 131b) qui est disposée sur une surface inférieure (103b) de la partie mobile (103). La surface de réflexion (M1a) est irradiée avec de la lumière (L1) qui diminue en intensité avec une distance croissante à partir d'un axe central (C0). La nervure (131a) dans une région spécifique de la surface inférieure (103b) correspondant au voisinage du centre d'une région irradiée avec la lumière (L1) dans la surface de réflexion (M1a) a une forme sensiblement incurvée dans une vue en plan.
PCT/JP2024/040760 2023-11-27 2024-11-18 Élément de réflexion optique Pending WO2025115667A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2023199813 2023-11-27
JP2023-199813 2023-11-27

Publications (1)

Publication Number Publication Date
WO2025115667A1 true WO2025115667A1 (fr) 2025-06-05

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2024/040760 Pending WO2025115667A1 (fr) 2023-11-27 2024-11-18 Élément de réflexion optique

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Country Link
WO (1) WO2025115667A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014122781A1 (fr) * 2013-02-08 2014-08-14 パイオニア株式会社 Actionneur
WO2015004710A1 (fr) * 2013-07-08 2015-01-15 パイオニア株式会社 Actionneur
JP2016170376A (ja) * 2015-03-16 2016-09-23 スタンレー電気株式会社 光偏向器
JP2018518708A (ja) * 2015-05-22 2018-07-12 ローベルト ボツシユ ゲゼルシヤフト ミツト ベシユレンクテル ハフツングＲｏｂｅｒｔ Ｂｏｓｃｈ Ｇｍｂｈ スキャン装置及びスキャン方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014122781A1 (fr) * 2013-02-08 2014-08-14 パイオニア株式会社 Actionneur
WO2015004710A1 (fr) * 2013-07-08 2015-01-15 パイオニア株式会社 Actionneur
JP2016170376A (ja) * 2015-03-16 2016-09-23 スタンレー電気株式会社 光偏向器
JP2018518708A (ja) * 2015-05-22 2018-07-12 ローベルト ボツシユ ゲゼルシヤフト ミツト ベシユレンクテル ハフツングＲｏｂｅｒｔ Ｂｏｓｃｈ Ｇｍｂｈ スキャン装置及びスキャン方法

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