Optical module

Abstract

To provide an optical module which can reduce effect of scan distortion caused by expansion of a scanning range.SOLUTION: An optical module according to an embodiment comprises: a light source unit; a scanning unit which scans a laser beam outputted from the light source unit; a support member which has a main surface on which the light source unit and the scanning unit are mounted; and a storage unit which houses the light source unit, the scanning unit, and the support member, and has a window unit which outputs the laser beam scanned by the scanning unit. The scanning unit comprises a scanning mirror, and a drive mechanism which drives the scanning mirror about a first swinging axis. A first plane is a plane which includes an optical axis of the laser beam incident to the scanning mirror, and the optical axis of the laser beam reflected by the scanning mirror, in a state where the drive of the scanning mirror is stopped. A second plane is the plane which is orthogonal to the first plane and includes the first swinging axis, in the state where the drive of the scanning mirror is stopped. The scanning mirror has a tilted surface which is tilted with respect to the second plane and reflects the laser beam.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an optical module. [Background technology]

[0002] As an optical module, an optical module that outputs light output from a light source unit while scanning it with a scanning unit is known (for example, Patent Documents 1 to 4). An example of the scanning unit is a MEMS (Micro Electro Mechanical Systems). An optical module that outputs scanned light is applied to a drawing device, a detection device, and the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-170965 A [Patent Document 2] International Publication No. 2018 / 101226 [Patent Document 3] JP 2018-72097 A [Patent Document 4] JP 2018-91630 A Summary of the Invention [Problem to be solved by the invention]

[0004] When light is scanned by the scanning unit, scanning distortion occurs. In particular, the effect of scanning distortion tends to become large when the scanning range is widened.

[0005] The present disclosure aims to provide an optical module capable of reducing the influence of scanning distortion caused by an expansion of the scanning range. [Means for solving the problem]

[0006] An optical module according to one embodiment includes a light source unit, a scanning unit that scans laser light output from the light source unit, a support member having a main surface on which the light source unit and the scanning unit are mounted, and a housing unit that houses the light source unit, the scanning unit, and the support member and has a window through which the laser light scanned by the scanning unit is output, the scanning unit having a scanning mirror and a driving mechanism that drives the scanning mirror around a first oscillation axis, a first plane being a plane that includes an optical axis of the laser light incident on the scanning mirror and an optical axis of the laser light reflected by the scanning mirror when the scanning mirror is stopped, a second plane being a plane that is perpendicular to the first plane and includes the first oscillation axis when the scanning mirror is stopped, and the scanning mirror has an inclined surface that is inclined with respect to the second plane and reflects the laser light. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide an optical module capable of reducing the influence of scanning distortion caused by an expansion of the scanning range. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a detection device to which an optical module according to an embodiment is applied. [Diagram 2] FIG. 2 is a perspective view of an optical module according to an embodiment. [Diagram 3] FIG. 3 is a plan view of the optical module shown in FIG. 1 with the cover removed. [Figure 4] FIG. 4 is a schematic diagram of the optical module 1 shown in FIG. 3 as viewed from the side. [Diagram 5] FIG. 5 is a schematic diagram for explaining the first plane. [Figure 6] FIG. 6 is a schematic diagram for explaining the second plane. [Figure 7] FIG. 7 is a plan view of the MEMS (scanning unit). [Figure 8] FIG. 8 is a side view of the scanning mirror included in the MEMS. [Figure 9] FIG. 9 is a schematic diagram for explaining an example of the arrangement conditions of the MEMS. [Figure 10] FIG. 10 is a schematic diagram for explaining a first arrangement example of the MEMS. [Figure 11] FIG. 11 is a schematic diagram for explaining a second arrangement example of the MEMS. [Figure 12] FIG. 12 is a schematic diagram for explaining a third arrangement example of the MEMS. [Figure 13] FIG. 13 is a schematic diagram showing a reference example of a MEMS arrangement when the scanning mirror does not have an inclined surface. [Figure 14] FIG. 14 is a schematic diagram for explaining a detection example in which scanning distortion occurs in the scanning line of the detection laser light that is scanned. [Figure 15] FIG. 15 is a schematic diagram for explaining a detection example in which no distortion of the scanning line of the scanning detection laser light occurs. [Figure 16] FIG. 16 is a graph showing the relationship between the angle θ between the normal to the second plane and the detection laser light when the scanning mirror is in a stopped state and the inclination angle φ of the first inclined plane with respect to the second plane in the case where there is no scanning distortion. [Figure 17] FIG. 17 is a schematic diagram showing a schematic configuration of an example of a two-axis MEMS. [Figure 18] FIG. 18 is a schematic diagram for explaining a modified example of the optical module. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0010] [1] An optical module according to one embodiment includes a light source unit, a scanning unit that scans a laser light output from the light source unit, a support member having a main surface on which the light source unit and the scanning unit are mounted, and a housing unit that houses the light source unit, the scanning unit, and the support member and has a window through which the laser light scanned by the scanning unit is output, the scanning unit having a scanning mirror and a drive mechanism that drives the scanning mirror around a first oscillation axis, a first plane being a plane that includes an optical axis of the laser light incident on the scanning mirror and an optical axis of the laser light reflected by the scanning mirror when the scanning mirror is stopped, a second plane being a plane that is perpendicular to the first plane and includes the first oscillation axis when the scanning mirror is stopped, and the scanning mirror has an inclined surface that is inclined with respect to the second plane and reflects the laser light.

[0011] In the above configuration, the scanning mirror has an inclined surface with respect to the second plane including the first oscillation axis, so that the influence of scanning distortion caused by the expansion of the scanning range can be reduced.

[0012] [2] In the optical module described in [1] above, the scanning mirror may have a plurality of the inclined surfaces arranged in parallel along the first oscillation axis. In this case, the manufacturing cost of the scanning mirror can be reduced. As a result, the manufacturing cost of the optical module can also be reduced.

[0013] [3] In the optical module described in [1] or [2] above, the driving mechanism may be configured to drive the scanning mirror about a second oscillation axis perpendicular to the first oscillation axis. In this case, by driving the scanning mirror about the second oscillation axis, the inclination angle of the inclined surface with respect to the second plane can be adjusted so as to reduce scanning distortion.

[0014] [4] In the optical module described in any one of [1] to [3] above, when the angle of the laser light incident on the inclined surface with respect to the normal to the second plane is θ (°) and the inclination angle of the inclined surface with respect to the second plane is φ (°), the scanning unit may be positioned such that φ satisfies equation (1) when the scanning mirror is stopped. φ(θ)=aθ 2 +bθ+c (1) In equation (1), a = -0.003032, b = 0.796134, and c = -0.879850.

[0015] In the optical module described in [4] above, the scanning section is disposed so as to satisfy formula (1), and therefore the scanning distortion can be further reduced.

[0016] [5] In the optical module described in any one of [1] to [4] above, when the scanning mirror is stopped, the second plane may be arranged at an angle to the main surface, and the inclined plane may be arranged parallel to the main surface.

[0017] In the optical module described in [5] above, since the inclined surface is parallel to the main surface, it is easy to adjust the angle of incidence of the laser light on the scanning mirror, and as a result, it is easy to adjust the reflection direction of the laser light.

[0018] [6] In the optical module according to any one of [1] to [4] above, the second plane may be arranged parallel to the main surface when the scanning mirror is stopped.

[0019] In the optical module described in [6] above, the second plane is parallel to the main surface. In this case, it is easy to install the scanning unit in the optical module.

[0020] [7] In the optical module described in any one of [1] to [4] above, when the scanning mirror is stopped, the second plane and the inclined surface may be arranged at an incline with respect to the main surface.

[0021] [Details of the embodiment of the present disclosure] Specific examples of the embodiments of the present disclosure will be described below with reference to the drawings. The present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope of the claims. In the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions are omitted.

[0022] The following is a specific description of the optical module 1 applied to the detection device 2. For convenience of explanation, the optical module 1 may be described using an x-axis, a y-axis, and a z-axis that are perpendicular to each other, as shown in FIG.

[0023] 1 is a schematic diagram of a detection device to which an optical module according to an embodiment is applied. The detection device 2 includes an optical module 1. The detection device 2 is a remote sensor that detects an arbitrary object 3 within a detection target range outside the detection device 2 (outside the optical module 1) by a detection laser light L1 output from the optical module 1 and scanned one-dimensionally. Specifically, the detection device 2 detects the object 3 based on a return light L2 generated when the detection laser light L1 is irradiated onto the object 3 within the detection target range of the detection laser light L1.

[0024] An example of the detection device 2 is LiDAR (Light Detection and Ranging, or Laser Imaging Detection and Ranging). The object 3 is not limited. Examples of the object 3 are a person, a car, a sign, and the like. The detection device 2 is mounted on, for example, a car, a drone, and the like.

[0025] Fig. 2 is a perspective view of an optical module 1 according to an embodiment. Fig. 3 is a plan view of the optical module 1 shown in Fig. 1 with a cover 42 removed. Fig. 4 is a schematic diagram of the optical module 1 shown in Fig. 3 as viewed from the side. In describing the optical module 1, the x-axis, y-axis, and z-axis shown in Figs. 2 to 4 may be used. The x-axis, y-axis, and z-axis are mutually perpendicular.

[0026] The optical module 1 includes a light source unit 10, a MEMS (Micro Electro Mechanical Systems) 20, and a support member 30 that supports the light source unit 10 and the MEMS (scanning unit) 20. An example of the support member 30 is a Peltier element (thermoelectric cooling element). FIGS. 3 and 4 show an example in which the support member 30 is a Peltier element. When the support member 30 is a Peltier element, the support member 30 has a heat absorption plate 31, a heat dissipation plate 32, and a plurality of semiconductor pillars 33. The plurality of semiconductor pillars 33 connect the heat absorption plate 31 and the heat dissipation plate 32. The optical module 1 includes a housing section 40 that houses the light source unit 10 and the MEMS (scanning unit) 20.

[0027] The light source unit 10 and the MEMS 20 are mounted on a surface (main surface) 30a of a support member 30. The normal direction of the surface 30a corresponds to the z-axis direction. In a form in which the support member 30 is a Peltier element, the surface 30a is the surface of a heat absorbing plate 31 provided in the Peltier element.

[0028] The light source unit 10 is mounted on a base 51 fixed to the surface 30a. The light source unit 10 has a light emitting element 11 that outputs a detection laser light L1, and a collimating unit 12 that collimates the detection laser light L1 output from the light emitting element 11.

[0029] The light emitting element 11 is fixed to an element mounting portion 52 fixed to the surface of a base 51. In the example shown in Figs. 3 and 4, the light emitting element 11 is arranged so as to output the detection laser light L1 in the y-axis direction. An example of the light emitting element 11 is a semiconductor light emitting element. In this embodiment, the light emitting element 11 is a laser diode (LD: Laser Diode). The light emitting element 11 may be an LD chip.

[0030] The detection laser light L1 is light having a wavelength used for a remote sensor. The wavelength range of the detection laser light L1 is, for example, 800 nm or more and 2500 nm or less. The wavelength of the detection laser light L1 is, for example, 830 nm, 850 nm, 905 nm, 940 nm, 1310 nm, or 1550 nm. In this embodiment, the detection laser light L1 is infrared light. The detection laser light L1 may be a pulsed light or a continuous light.

[0031] The collimator 12 is disposed on the optical path of the detection laser light L1 output from the light emitting element 11. An example of the collimator 12 is a lens. Specifically, an example of the collimator 12 is a collimator lens.

[0032] The MEMS 20 is disposed closer to the support member 30 than the light source unit 10. In such an arrangement of the MEMS 20, the position of the detection laser light L1 output from the light source unit 10 differs from the position of the MEMS 20 in the z-axis direction. The optical module 1 has a mirror 60 for making the detection laser light L1 incident on the MEMS 20.

[0033] The mirror 60 is disposed in the optical path of the detection laser light L1 output from the light source unit 10. The mirror 60 functions as an optical path changing element that changes the optical path of the detection laser light L1 toward the MEMS 20. The mirror 60 is inclined with respect to the z-axis direction so as to reflect the detection laser light L1 toward the MEMS 20. The mirror 60 is fixed to a support 53. An example of the support 53 is a plate-like member, but the shape of the support 53 is not limited. The shape of the mirror 60 may be, for example, rectangular (or square) or circular.

[0034] The MEMS 20 is a one-axis MEMS that one-dimensionally scans the detection laser light L1. The MEMS 20 includes a scanning mirror 21. The scanning mirror 21 oscillates around a first oscillation axis α (see FIG. 3).

[0035] 2 to 4, the housing unit 40 has a support substrate 41 and a cover 42. The housing unit 40 is a package that houses the light source unit 10 and the MEMS 20. The cover 42 is fixed to the support substrate 41. This forms a housing space that houses the light source unit 10 and the MEMS 20. In this embodiment, the housing space is hermetically sealed by the support substrate 41 and the cover 42.

[0036] The support substrate 41 is a plate-like member on which the light source section 10 and the MEMS 20 are mounted. The support substrate 41 is, for example, a stem. In this embodiment, as shown in FIG. 4, the support member 30 is fixed to the support substrate 41. Specifically, the surface of the support member 30 opposite to the surface 30a is fixed to the support substrate 41. By fixing the support member 30 to the support substrate 41 in this manner, the light source section 10 and the MEMS 20 are mounted on the support substrate 41.

[0037] An example of the material of the support substrate 41 is an iron alloy. The support substrate 41 may be nickel-plated or gold-plated. In this embodiment, the shape of the support substrate 41 in a plan view (shape as viewed from the z-axis direction) is rectangular. The shape of the support substrate 41 in a plan view may be a square, a polygon other than a rectangle, or a circle.

[0038] A plurality of conductive members 46 are provided on the support substrate 41. The conductive members 46 are rod-shaped members. An example of the conductive members 46 is a lead pin. The plurality of conductive members 46 penetrate the support substrate 41 in the z-axis direction while being insulated from the support substrate 41. An insulating member (e.g., a cured insulating resin) may be provided around the plurality of conductive members 46. This allows each conductive member 46 to be insulated from the support substrate 41.

[0039] A first end of each conductive member 46 protrudes into the housing 40. A second end of each conductive member 46 protrudes outside the housing 40. The second end is an end opposite to the first end of the conductive member 46. The conductive members 46 function as terminals for connecting electronic components in the housing 40 to the outside. The electronic components in the housing 40 are the light-emitting element 11, the MEMS 20, etc. For example, when the optical module 1 is attached to a circuit board, the second ends of the conductive members 46 are electrically connected to a wiring pattern of the circuit board. This allows the optical module 1 to be electrically connected to a control device (or a control circuit) for controlling the optical module 1 via the circuit board.

[0040] 2, the cover 42 has a body portion 43 and a top wall portion 44. An example of the cover 42 is a cap. The body portion 43 is a hollow body. The body portion 43 is fixed to the support substrate 41 by, for example, welding. The top wall portion 44 closes an opening in the body portion 43 that is located opposite the support substrate 41. The top wall portion 44 is a wall portion that faces the support substrate 41.

[0041] The storage unit 40 has a window 45. The window 45 is a portion that outputs the detection laser light L1 to the outside of the storage unit 40. The window 45 is a transparent member attached to an opening 44a formed in the top wall 44. The material of the window 45 may be glass or plastic.

[0042] In the optical module 1 having the above configuration, the detection laser light L1 output from the light source unit 10 is reflected by the mirror 60 and then enters the scanning mirror 21. The detection laser light L1 that enters the scanning mirror 21 is reflected by the scanning mirror 21 and then output to the outside of the optical module 1 through the window unit 45. The scanning mirror 21 oscillates around the first oscillation axis α. As a result, the optical module 1 outputs the detection laser light L1 that has been scanned one-dimensionally.

[0043] The optical module 1 will be further described with a focus on the MEMS 20. First, the first plane P1 and the second plane P2 used in the following description will be described with reference to Figures 5 and 6. The first plane P1 and the second plane P2 are planes that are defined when the driving of the scanning mirror 21 is stopped.

[0044] FIG. 5 is a schematic diagram for explaining the first plane P1. FIG. 5 shows the first inclined surface 212a that reflects the detection laser light L1, the optical axis C1 of the detection laser light L1 incident on the first inclined surface 212a, and the optical axis C2 of the detection laser light L1 reflected by the first inclined surface 212a. The scanning mirror 21 includes the first inclined surface 212a. The first plane P1 is a plane that includes the optical axis C1 and the optical axis C2. The first plane P1 is the yz plane in FIG. 4. FIG. 6 is a schematic diagram for explaining the second plane P2. The second plane P2 is a plane that includes the first oscillation axis α and is perpendicular to the first plane P1. The second plane P2 is the st plane in FIG. 7 described later.

[0045] Next, an example of the MEMS 20 will be described. Fig. 7 is a plan view of the MEMS 20. The MEMS 20 has a scanning mirror 21, a frame 22, and a driving mechanism 23. The MEMS 20 will be described using the s-axis and t-axis shown in Fig. 7, which are orthogonal to each other. The s-axis corresponds to the x-axis shown in Figs. 2 to 4.

[0046] In this embodiment, the frame portion 22 has a first side portion 22a, a second side portion 22b, a third side portion 22c, and a fourth side portion 22d. The first side portion 22a and the second side portion 22b face each other. The first side portion 22a and the second side portion 22b extend in the s-axis direction. The third side portion 22c and the fourth side portion 22d face each other. The third side portion 22c and the fourth side portion 22d extend in the t-axis direction. The third side portion 22c and the fourth side portion 22d connect the first side portion 22a and the second side portion 22b.

[0047] The driving mechanism 23 is configured to be able to swing the scanning mirror 21 around a first oscillation axis α. The driving mechanism 23 has a first shaft portion 23a and a second shaft portion 23b that support the scanning mirror 21. The first shaft portion 23a and the second shaft portion 23b extend in the t-axis direction. The first shaft portion 23a connects the first side portion 22a and the scanning mirror 21. The second shaft portion 23b connects the second side portion 22b and the scanning mirror 21. The central axes of the first shaft portion 23a and the second shaft portion 23b coincide. The first shaft portion 23a and the second shaft portion 23b function as a torsion spring that twists when a torque is applied around the central axis by a torque applying portion (not shown). The scanning mirror 21 swings around the central axis of the first shaft portion 23a and the second shaft portion 23b. Therefore, the central axis of the first shaft portion 23a and the second shaft portion 23b is the first oscillation axis α. The first oscillation axis α extends in the t-axis direction.

[0048] Fig. 8 is a side view of the scanning mirror 21 of the MEMS 20. Specifically, Fig. 8 shows the scanning mirror 21 as viewed from the white arrow shown in Fig. 7. The s-axis and t-axis shown in Fig. 8 correspond to the s-axis and t-axis shown in Fig. 7. For the sake of explanation, Fig. 8 also illustrates the first shaft portion 23a and the second shaft portion 23b, and the second plane P2.

[0049] As shown in Fig. 7 and Fig. 8, the scanning mirror 21 has at least one first inclined surface (inclined surface) 212a. Fig. 7 and Fig. 8 illustrate an example in which the scanning mirror 21 has three first inclined surfaces 212a, but the number of the first inclined surfaces 212a may be one or two, or may be four or more. An example of an example in which the scanning mirror 21 has a plurality of first inclined surfaces 212a will be specifically described below.

[0050] The scanning mirror 21 has a flat plate portion 211 and a plurality of pillar portions 212. The flat plate portion 211 and the plurality of pillar portions 212 are integrated together. For ease of explanation, the boundary surface between the flat plate portion 211 and the plurality of pillar portions 212 is referred to as the surface 211a of the flat plate portion 211. In FIG. 8, the surface 211a is indicated by a solid line. The first shaft portion 23a and the second shaft portion 23b are connected to the flat plate portion 211. The second plane P2 is perpendicular to the thickness direction of the flat plate portion 211. The second plane P2 is parallel to the surface 211a.

[0051] The multiple columnar portions 212 are arranged in parallel along the first oscillation axis α. Each columnar portion 212 extends in the s-axis direction. Each columnar portion is a triangular prism. Each columnar portion 212 has a first inclined surface 212a and a second inclined surface 212b. The connection portion between the first inclined surface 212a and the second inclined surface 212b constitutes the top of the columnar portion 212. The multiple first inclined surfaces 212a are arranged in parallel along the first oscillation axis α. The multiple first inclined surfaces 212a are parallel. The multiple second inclined surfaces 212b are also arranged in parallel along the first oscillation axis α. The multiple second inclined surfaces 212b are parallel.

[0052] The first inclined surface 212a is a reflecting surface that reflects the detection laser light L1. The first inclined surface 212a is inclined at an inclination angle φ (°) with respect to the surface 211a. As described above, since the surface 211a and the second plane P2 are parallel, the first inclined surface 212a is inclined at an inclination angle φ with respect to the second plane P2.

[0053] The scanning mirror 21, the frame 22, the first shaft portion 23a, and the second shaft portion 23b are integrally formed of silicon. Specifically, the scanning mirror 21, the frame 22, the first shaft portion 23a, and the second shaft portion 23b are formed by micromachining a silicon base material.

[0054] A description will be given of an example of the arrangement of the MEMS 20. The MEMS 20 is arranged so that the detection laser light L1 scanned by the scanning mirror 21 does not interfere with the mirror 60. An example of the arrangement condition of the MEMS 20 will be described with reference to FIG.

[0055] FIG. 9 is a schematic diagram for explaining an example of the arrangement condition of the MEMS 20. FIG. 9 shows the relationship between elements necessary for explaining the arrangement condition. FIG. 9 is a diagram when the scanning mirror 21 is stopped. FIG. 9 shows a state in which the detection laser light L1 on the first plane P1 is incident on the first inclined surface 212a and is further reflected by the first inclined surface 212a. As shown in FIG. 9, the angle between the normal n of the second plane P2 including the first oscillation axis α and the detection laser light L1 incident on the first inclined surface 212a in the state in which the scanning mirror 21 is stopped is θ (°). The MEMS 20 is arranged such that the inclination angle φ satisfies the formula (1) in the state in which the scanning mirror 21 is stopped. The formula (1) is expressed in degrees. "The inclination angle φ satisfies the formula (1)" means that the inclination angle φ is within an angle range including a design error, an installation error, and a measurement error centered on the inclination angle φ (θ) obtained by the formula (1). Specifically, the inclination angle φ is within a range of ±5° of φ(θ) calculated by formula (1). Although the case where the inclination angle φ is calculated from a known angle θ using formula (1) has been described above, the angle θ may be calculated from a known inclination angle φ, and "the inclination angle φ satisfies formula (1)" includes this case. φ(θ)=aθ 2 +bθ+c (1) a, b, and c in formula (1) are as follows: a=-0.003032 b=0.796134 c=-0.879850

[0056] The direction of the arrow indicating the angle shown in FIG. 9 is taken as the positive direction for the angle θ and the inclination angle φ.

[0057] Next, a first arrangement example, a second arrangement example, and a third arrangement example will be described as specific arrangement examples of the MEMS 20 in the optical module 1. In the first arrangement example, the second arrangement example, and the third arrangement example, the second side portion 22b of the MEMS 20 is located near the base 51.

[0058] (1st placement example) 10 is a schematic diagram for explaining a first arrangement example of the MEMS 20. FIG 10 corresponds to a partially enlarged view of FIG 4.

[0059] The MEMS 20 is disposed such that the first inclined surface 212a is parallel to the surface 30a when the driving of the scanning mirror 21 is stopped.

[0060] In the first arrangement example, the MEMS 20 is supported by a support 53. The second side portion 22b may be fixed to a pedestal 54 provided on the surface 30a.

[0061] (Second placement example) 11 is a schematic diagram for explaining a second arrangement example of the MEMS 20. The MEMS 20 is arranged such that the second plane P2 is parallel to the surface 30a when the driving of the scanning mirror 21 is stopped.

[0062] (3rd arrangement example) 12 is a schematic diagram for explaining a third arrangement example of the MEMS 20. The MEMS 20 is arranged such that both the first inclined surface 212a and the second plane P2 are inclined with respect to the surface 30a when the scanning mirror 21 is stopped. In the third arrangement example, the MEMS 20 is also supported by the support body 53. The second side portion 22b may be fixed to a pedestal 54 provided on the surface 30a.

[0063] When the detection laser light L1 output from the optical module 1 is irradiated onto an object 3 within the scanning range of the detection laser light L1, as shown in FIG. 1, it is possible to obtain information such as the position and distance of the object 3 by detecting the return light L2 from the object 3.

[0064] In the optical module 1, the scanning mirror 21 has the first inclined surface 212a, so that the scanning distortion can be reduced.

[0065] Fig. 13 is a schematic diagram showing a reference arrangement example of MEMS when the scanning mirror does not have an inclined surface. The MEMS in the reference arrangement example shown in Fig. 13 is referred to as MEMS200, the scanning mirror of MEMS200 is referred to as scanning mirror 201, and the optical module including MEMS200 is referred to as optical module 100. The configuration of MEMS200 is the same as that of MEMS20, except that scanning mirror 201 does not have first inclined surface 212a. The configuration of optical module 100 is also the same as that of optical module 1, except that MEMS200 is included instead of MEMS200.

[0066] In the optical module 100, the scanning mirror 201 is a flat plate that does not have an inclined surface. In the MEMS 200, the reflecting surface and the second plane P2 of the scanning mirror 201 are arranged parallel to the surface 30a.

[0067] In the optical module 100, the detection laser beam L1 is also reflected by the mirror 60 and then incident on the scanning mirror 201. The detection laser beam L1 incident on the scanning mirror 201 is reflected by the scanning mirror 201. In the configuration of the optical module 100 shown in FIG. 13, the scanning distortion shown in FIG. 14 occurs.

[0068] An example of detection of an object 3 when there is scanning distortion and when there is no scanning distortion will be described with reference to Fig. 14 and Fig. 15. Fig. 14 is a schematic diagram for explaining an example of detection when there is scanning distortion in the scanning line of the scanned detection laser light L1. Fig. 15 is a schematic diagram for explaining an example of detection when there is no scanning distortion in the scanning line of the scanned detection laser light L1.

[0069] As shown in FIG. 14, a case is assumed in which a person standing on the ground is detected as the object 3. The locus of the irradiation point of the scanned detection laser light L1 is called a scanning line. The scanning line 71b shown by the dashed line in FIG. 14 is a scanning line when no scanning distortion occurs. When no scanning distortion occurs, the detection laser light L1 is scanned at a constant height from the ground. Therefore, the "person" that is the detection target can be properly detected within the scanning range. In the optical module 100 having the configuration shown in FIG. 13, as shown in FIG. 14, in the case of the detection laser light L1 outputted from the optical module 100 and scanned, the height of the detection laser light L1 from the ground changes according to the scanning, as shown by the scanning line 71a shown by the solid line. That is, the scanning distortion occurs in the optical module 100. In this case, the height of the detection laser light L1 with respect to the ground may deviate from the assumed height range. Therefore, the "person" that would have been detectable if the scanning distortion did not occur cannot be properly detected. The above-mentioned scanning distortion becomes more prominent as the scanning angle range that defines the scanning range becomes larger. For example, as shown in FIG. 14, in the scanning range A1, a person can be detected even if scanning distortion occurs, whereas if the scanning range is expanded to scanning range A2, an area will arise in which a person cannot be detected.

[0070] On the other hand, in the optical module 1, the scanning mirror 21 has the first inclined surface 212a, so that the scanning distortion can be reduced as described above. Specifically, the scanning mirror 21 has a configuration in which the scanning mirror 21 is inclined with respect to the second plane P2 and has the first inclined surface 212a that reflects the detection laser light L1, so that the scanning distortion can be reduced more than that of the optical module 100 shown in FIG. 13. Therefore, in the optical module 1, the detection laser light L1 can be scanned at a certain height from the ground, as in the scanning line 71 shown in FIG. 15. In particular, when the optical module 1 has a configuration that satisfies the formula (1), the scanning distortion can be reduced more reliably. As a result, the scanning distortion can be reduced even if the scanning range A is expanded. That is, in the optical module 1, it is possible to expand the detection target range while at least maintaining the detection accuracy of the object 3. The scanning range A shown in FIG. 15 corresponds to the scanning range A2 shown in FIG. 14.

[0071] The scanning range A is defined by the deflection angle of the scanning mirror 21 about the first oscillation axis α and the angle θ (or the tilt angle φ).

[0072] In a configuration in which the MEMS 20 is disposed closer to the surface 30a than the light source unit 10, the distance between the surface 30a and the position of the MEMS 20 farthest from the surface 30a can be reduced. Therefore, the height of the optical module 1 along the z-axis direction can also be reduced, thereby realizing miniaturization of the optical module 1.

[0073] 10, the first inclined surface 212a is parallel to the surface 30a, so that it is easy to adjust the angle of incidence of the detection laser light L1 on the scanning mirror 21. As a result, it is easy to adjust the reflection direction of the detection laser light L1. Specifically, the angle of incidence of the detection laser light L1 can be adjusted by adjusting the inclination angle of the mirror 60.

[0074] 11, the second plane P2 is parallel to the surface 30a. In this case, it is easy to install the MEMS 20 in the optical module 1. Therefore, the optical module 1 is easy to manufacture, and the optical module 1 can be easily mass-produced.

[0075] FIG. 16 is a graph showing the relationship between angle θ (°) and tilt angle φ (°) when there is no scanning distortion in a configuration in which the scanning mirror 21 has a first tilted surface 212a as described in this disclosure.

[0076] Specifically, Fig. 16 was obtained as follows. In a configuration in which the scanning mirror 21 has the first inclined surface 212a, the vector of the detection laser light L1 that is incident on the first inclined surface 212a, reflected by the first inclined surface 212a, and scanned around the first oscillation axis α was calculated by regarding the detection laser light L1 as a light ray, and the scanning line 71 was calculated. In the calculation, the positional relationship of the second plane P2 and the first inclined surface 212a to the surface 30a and the positional relationship of the first inclined surface 212a to the second plane P2 were the positional relationship shown in Fig. 12. Fig. 12 shows the positional relationship of the second plane P2 and the first inclined surface 212a to the surface 30a and the positional relationship of the first inclined surface 212a to the second plane P2 two-dimensionally, but since the scanning mirror 21 oscillates around the first oscillation axis α, the vector of the scanned detection laser light L1 was calculated three-dimensionally. FIG. 16 was obtained by plotting the calculated values ​​of the inclination angle φ against the angle θ when the scanning line 71 does not have scanning distortion. The function φ(θ) showing the approximate curve obtained by fitting the multiple calculated values ​​shown in FIG. 16 with a quadratic function is Equation (1). Therefore, by arranging the MEMS 20 so that the inclination angle φ satisfies Equation (1), the scanning distortion can be reduced more reliably.

[0077] When the scan mirror 21 has a plurality of first inclined surfaces 212a, the manufacturing cost of the scan mirror 21 can be reduced. In one example, the scan mirror 21 is manufactured by micro-machining a silicon base material. When there is one first inclined surface 212a, a thicker base material is required as the silicon base material before processing, which increases the cost. In contrast, when the scan mirror 21 has a plurality of first inclined surfaces 212a, a thinner silicon base material can be used, which reduces the manufacturing cost.

[0078] Although various embodiments and modifications according to the present disclosure have been described above, the present disclosure is not limited to the exemplified embodiments and modifications.

[0079] The MEMS 20 may be a two-axis MEMS. FIG. 17 is a schematic diagram showing a schematic configuration of one example of a two-axis MEMS. The s-axis and t-axis shown in FIG. 17 correspond to the s-axis and t-axis shown in FIG. 7. The MEMS 20A shown in FIG. 17 is configured so that the scanning mirror 21 can be driven around a first oscillation axis α and can be driven around a second oscillation axis β perpendicular to the first oscillation axis α. The MEMS 20A includes the scanning mirror 21, a frame 22-1, a frame 22-2, and a driving mechanism 23A. The configuration of the scanning mirror 21 is the same as that of the MEMS 20 shown in FIG. 7, and therefore a description of the scanning mirror 21 will be omitted.

[0080] The frame portion 22-1 surrounds the scanning mirror 21. The frame portion 22-1 corresponds to the frame portion 22 of the MEMS 20 shown in Fig. 7. The frame portion 22-1 has a first side portion 22a-1, a second side portion 22b-1, a third side portion 22c-1, and a fourth side portion 22d-1, which correspond to the first side portion 22a, the second side portion 22b, the third side portion 22c, and the fourth side portion 22d of the frame portion 22.

[0081] The driving mechanism 23A has a first shaft portion 23a and a second shaft portion 23b that support the scanning mirror 21. The first shaft portion 23a of the driving mechanism 23A is the same as the first shaft portion 23a of the driving mechanism 23 except that the first shaft portion 23a connects the first side portion 22a-1 to the scanning mirror 21 instead of the first side portion 22a. The second shaft portion 23b of the driving mechanism 23A is the same as the second shaft portion 23b of the driving mechanism 23 except that the second shaft portion 23b connects the second side portion 22b-1 to the scanning mirror 21 instead of the second side portion 22b. Therefore, in the MEMS 20A as well, the central axis of the first shaft portion 23a and the second shaft portion 23b is the first oscillation axis α.

[0082] In the MEMS 20A, a portion configured with the scanning mirror 21, the frame portion 22-1, the first shaft portion 23a, and the second shaft portion 23b is the same as that of the MEMS 20 shown in Fig. 7. Therefore, in the MEMS 20A, a portion configured with the scanning mirror 21, the frame portion 22-1, the first shaft portion 23a, and the second shaft portion 23b is referred to as an internal MEMS 20-1. Since the internal MEMS 20-1 has the same configuration as that of the MEMS 20, in the internal MEMS 20-1, the scanning mirror 21 oscillates around the first oscillation axis α in the same manner as in the case of the MEMS 20.

[0083] The frame portion 22-2 surrounds the internal MEMS 20-1. The material of the frame portion 22-2 is the same as that of the frame portion 22. The frame portion 22-2 has a first side portion 22a-2, a second side portion 22b-2, a third side portion 22c-2, and a fourth side portion 22d-2. The first side portion 22a-2 and the second side portion 22b-2 face each other. The first side portion 22a-2 and the second side portion 22b-2 extend in the s-axis direction. The third side portion 22c-2 and the fourth side portion 22d-2 face each other. The third side portion 22c-2 and the fourth side portion 22d-2 extend in the t-axis direction. The third side portion 22c-2 and the fourth side portion 22d-2 connect the first side portion 22a-2 and the second side portion 22b-2.

[0084] The driving mechanism 23A further includes a third shaft portion 23c and a fourth shaft portion 23d in order to drive the scanning mirror 21 around the second oscillation axis β. The material of the third shaft portion 23c and the fourth shaft portion 23d is the same as that of the first shaft portion 23a (or the second shaft portion 23b).

[0085] The third shaft portion 23c and the fourth shaft portion 23d extend in the s-axis direction. The third shaft portion 23c connects the third side portion 22c-2 and the third side portion 22c-1. The fourth shaft portion 23d connects the fourth side portion 22d-2 and the fourth side portion 22d-1. The central axes of the third shaft portion 23c and the fourth shaft portion 23d coincide. The central axes of the third shaft portion 23c and the fourth shaft portion 23d function as the second oscillation axis β. The third shaft portion 23c and the fourth shaft portion 23d function as a torsion spring that is twisted by the application of torque around the central axis by a torque application portion (not shown).

[0086] In the MEMS 20A, the third shaft portion 23c and the fourth shaft portion 23d are swung around the central axes, whereby the internal MEMS 20-1 having the scanning mirror 21 swung around the second oscillation axis β. Therefore, in the MEMS 20A, the scanning mirror 21 can be swung around the second oscillation axis β.

[0087] The MEMS 20A is applied to the optical module 1 in place of the MEMS 20. When the MEMS 20A is used, the angle θ of the detection laser light L1 incident on the first inclined surface 212a with respect to the normal n of the second plane P2 can be adjusted by rotating the scanning mirror 21 around the second oscillation axis β. Therefore, for example, in the first arrangement example, the second arrangement example, and the third arrangement example described above, when the MEMS 20A is adopted instead of the MEMS 20, the angle θ can be adjusted by rotating the scanning mirror 21 around the second oscillation axis β, so that the MEMS 20A can be easily installed. Furthermore, after the MEMS 20A is mounted on the optical module 1, the angle θ can be finely adjusted while the detection laser light L1 is output, so that the scanning distortion can be further reduced.

[0088] 18, the MEMS 20 may be fixed to a base 55 having an inclined surface, and the detection laser light L1 from the light source unit 10 may be directly incident on the first inclined surface 212a. The optical module 1A does not have a mirror 60.

[0089] In the optical module 1A as well, the MEMS 20 may be arranged so as to satisfy the arrangement condition explained using formula (1).

[0090] The light source unit 10 may have a plurality of light-emitting elements 11. In this case, the light source unit 10 includes a plurality of collimating units 12 corresponding to the plurality of light-emitting elements 11, and a multiplexing unit that multiplexes the laser light output from the plurality of light-emitting elements 11. The multiplexing unit outputs multiplexed light of the plurality of laser light beams that are output from the plurality of light-emitting elements 11 and then collimated by the plurality of collimating units 12. The multiplexed light output from the multiplexing unit is the detection laser light L1 output from the light source unit 10. The laser light output from the plurality of light-emitting elements 11 may be light in the wavelength range exemplified above. The central wavelengths of the plurality of light-emitting elements 11 may be the same or different. The wavelength of the laser light output from one of the plurality of light-emitting elements 11 may be a wavelength in the visible region.

[0091] The scanning unit is not limited to MEMS as long as it is configured to be capable of scanning the detection laser light.

[0092] The optical module according to the present disclosure can be applied to a drawing device in addition to the detection device exemplified above.

[0093] The various embodiments and modifications described above may be combined as appropriate without departing from the spirit of the present disclosure. [Explanation of symbols]

[0094] 1,1A...Optical module 2. Detection device 3…object 10...Light source section 11...Light emitting element 12…Collimation section 20, 20A…MEMS (scanning section) 20-1…Internal MEMS 21...Scanning mirror 211...Flat plate part 211a…Surface 212...Columnar part 212a...First slope (slope) 212b…Second slope 22, 22-1, 22-2…Frame section 22a, 22a-1, 22a-2...first side part 22b, 22b-1, 22b-2…Second side 22c, 22c-1, 22c-2...Third side 22d,22d-1,22d-2...4th side 23, 23A…Drive mechanism 23a...First shaft part 23b…Second shaft part 23c...Third shaft part 23d...4th axis part 30...Support member 30a…Surface (principal surface) 31...Heat absorption plate 32...Heat sink 33...Semiconductor pillar 40…Storage section 41...Support substrate 42…Cover 43…Torso 44…Ceiling wall 44a…Aperture 45…Window section 46...Conductive material 51…Pedestal 52...Element mounting section 53...Support 54…Pedestal 55…Pedestal 60…Mirror 71, 71a, 71b...scanning lines 100...Optical module 200…MEMS 201...Scanning mirror α…First oscillation axis β…Second oscillation axis P1...first plane P2…Second plane C1…optical axis C2…optical axis L1…Detection laser light (laser light) L2…Return light A, A1, A2...Scanning range n...Normal θ...angle (angle of the laser light incident on the inclined surface with respect to the normal of the second plane) φ...Tilt angle (tilt angle of the inclined surface relative to the second plane).

Claims

1. A light source unit; A scanning unit that scans the laser light output from the light source unit; a support member having a main surface on which the light source unit and the scanning unit are mounted; a housing section that houses the light source section, the scanning section, and the support member, and has a window section through which the laser light scanned by the scanning section is output; Equipped with The scanning unit is A scanning mirror; a driving mechanism that drives the scanning mirror around a first oscillation axis; having a first plane is a plane including an optical axis of the laser light incident on the scanning mirror and an optical axis of the laser light reflected by the scanning mirror in a state in which the scanning mirror is stopped; the second plane is a plane that is perpendicular to the first plane and includes the first oscillation axis when the scanning mirror is stopped; the scanning mirror has an inclined surface that is inclined with respect to the second plane and reflects the laser light; Optical module.

2. The scanning mirror has a plurality of the inclined surfaces arranged in parallel along the first oscillation axis.

2. The optical module according to claim 1.

3. the driving mechanism is configured to be capable of driving the scanning mirror around a second oscillation axis perpendicular to the first oscillation axis.

2. The optical module according to claim 1.

4. When an angle of the laser light incident on the inclined surface with respect to a normal line of the second plane is θ (°) and an inclination angle of the inclined surface with respect to the second plane is φ, the scanning unit is disposed such that φ satisfies Equation (1) when the driving of the scanning mirror is stopped. The optical module according to claim 1 . φ(θ)=αθ ２ +~+c・・・(1) In equation (1), a = -0.003032, b = 0.796134, and c = -0.879850.

5. When the scanning mirror is stopped, the second plane is inclined with respect to the main surface, and the inclined surface is parallel to the main surface.

2. The optical module according to claim 1.

6. When the scanning mirror is stopped, the second plane is disposed parallel to the main surface.

2. The optical module according to claim 1.

7. When the scanning mirror is stopped, the second plane and the inclined surface are disposed to be inclined with respect to the main surface.

2. The optical module according to claim 1.

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