Lens and optical sensor system

Abstract

The purpose of the present disclosure is to improve condensing accuracy pertaining to incident light for a distance range in which the distance to a lens is wider. A lens (1) includes: a lens surface region (2) which has a lens surface (20) that condenses incident light and a non-lens surface region (3) in which the lens surface (20) is not present. The lens surface (20) has a first lens surface (21) which is a convex lens surface and configured as a convex curved surface (CV1) including a vertex (P1) and a second lens surface (22) which is an aspherical surface having a different curvature from the first lens surface (21). The principal ray axis (222) of the second lens surface (22) is non-coaxial with the principal ray axis (211) of the first lens surface (21).

Description

Lens and optical sensor system

[0001] The present disclosure relates generally to lenses and optical sensor systems, and more particularly to lenses having lens surfaces that focus incident light, and optical sensor systems including such lenses.

[0002] Patent Document 1 discloses a laser radar device. The laser radar device includes a laser radar unit and a control device for the laser radar unit. The laser radar unit includes an optical block. The optical block includes a light-emitting element as a laser light source, a projection lens that defines a projection axis of the laser light, a receiving lens that focuses reflected light (laser light) reflected by an object, and a light-receiving element that receives the focused reflected light by the receiving lens. The receiving lens includes a long-distance lens portion that is aspherical and capable of guiding reflected light parallel to the receiving axis to the light-receiving element. The receiving lens also includes a cylindrical lens portion centered on a central axis perpendicular to the receiving axis and capable of guiding a portion of reflected light parallel to the receiving axis and a portion of reflected light non-parallel to the receiving axis to the light-receiving element. This laser radar device can effectively achieve a wide object detection range.

[0003] Japanese Patent Application Laid-Open No. 2021-47141

[0004] Incidentally, Patent Document 1 defines a distance of 1.5 m or less as a "short distance" and a distance longer than 1.5 m as a "long distance." In other words, a lens unit for short distances and a lens unit for long distances are provided with 1.5 m as the boundary. However, for light from distances significantly closer than 1.5 m, such as an ultra-short distance of 50 mm or a long distance of 5 m, the light receiving lens (lens) described in Patent Document 1 may not be able to receive a sufficient amount of light.

[0005] The present disclosure has been made in view of the above-mentioned circumstances, and aims to provide a lens and an optical sensor system that improve the focusing accuracy of incident light over a wider range of distances to the lens.

[0006] A lens according to one aspect of the present disclosure includes a lens surface region having a lens surface that focuses incident light, and a non-lens surface region where the lens surface is not present. The lens surface includes a first lens surface that is a convex lens surface configured as a convex curved surface including a vertex, and a second lens surface that is an aspheric surface with a different curvature from that of the first lens surface. The axis of a chief ray of the second lens surface is non-coaxial with the axis of a chief ray of the first lens surface.

[0007] An optical sensor system according to one aspect of the present disclosure includes a light projecting unit, the above-described lens, and a light receiving element. The light projecting unit projects laser light onto a measurement object. The lens collects light reflected from the measurement object. The light receiving element receives the light collected by the lens and converts it into an electrical signal. The light receiving element is positioned so that the light receiving axis of the light receiving element coincides with the optical axis passing through the vertex. The light projecting axis and the light receiving axis of the light projecting unit are parallel to each other on the optical axis.

[0008] FIG. 1 is an external perspective view of a lens according to an embodiment, as seen from the front side. FIG. 2 is a schematic front view of the lens. FIG. 3 is a sag diagram showing the amount of sag relative to the vertex of the first lens surface of the lens. FIG. 4A is a conceptual diagram of an optical sensor system including the lens when used at a "long distance." FIG. 4B is a conceptual diagram of the optical sensor system when used at an "ultra-close distance." FIG. 5 is a block diagram of the optical sensor system. FIG. 6A is an external perspective view of a plano-convex lens for illustrating the first lens surface of the lens. FIG. 6B is an external perspective view of a cylindrical lens for illustrating the second lens surface of the lens. FIG. 7 is a graph showing the distance measurement characteristics of the lens. FIG. 8A is a conceptual diagram showing an application example 1 of the optical sensor system. FIG. 8B is a conceptual diagram showing an application example 2 of the optical sensor system. FIG. 9A is a schematic front view of a modified example 1-1 of the lens. FIG. 9B is a schematic front view of another example of the modified example 1-1. FIG. 10A is a schematic front view of Modification 1-2 of the lens of the same reference numeral. FIG. 10B is a schematic front view of yet another example of Modification 1-2 of the same reference numeral. FIG. 11 is a schematic front view of Modification 2 of the lens of the same reference numeral. FIG. 12A is a schematic front view of Modification 3 of the lens of the same reference numeral. FIG. 12B is a schematic front view of yet another example of Modification 3 of the same reference numeral. FIG. 13A is a schematic front view of Modification 4 of the lens of the same reference numeral. FIG. 13B is a cross-sectional view taken along line II of FIG. 13A. FIG. 14A is a schematic front view of yet another example of Modification 4 of the same reference numeral. FIG. 14B is a cross-sectional view taken along line II-II of FIG. 14A. FIG. 15A is a schematic front view of Modification 5 of the lens of the same reference numeral. FIG. 15B is an external perspective view of a toroidal lens for explaining a second lens surface in Modification 5 of the same reference numeral. FIG. 15C is an external perspective view of a cylindrical lens of the same reference numeral. Fig. 16 is a conceptual diagram of the cross-sectional shapes of multiple light projection spots to explain a modified example (Modification 6) of the light projection unit in the optical sensor system of the same. Fig. 17 is a graph showing the distance measurement characteristics of lenses corresponding to the multiple light projection spots of the same for detection distances of 100 mm to 400 mm. Fig. 18A is a schematic front view of Modification 7 of the same lens.Fig. 18B is a cross-sectional view taken along line III-III in Fig. 18A. Fig. 19 is an external perspective view of the lens of Modification 8 of the same, as viewed from the front side. Fig. 20A is a characteristic diagram showing the light intensity distribution of the lens shown in Fig. 1. Fig. 20B is a characteristic diagram showing the light intensity distribution of Modification 8 of the same. Fig. 21 is a graph showing the distance measurement characteristics of Modification 8 of the same. Fig. 22 is an external perspective view of a cylindrical lens for explaining the second lens surface in Modification 8 of the same.

[0009] (Summary) Lenses and optical sensor systems according to embodiments and modifications will be described below with reference to the drawings. Note that the following embodiments and modifications are merely examples of various embodiments of the present disclosure. Furthermore, the following embodiments and modifications can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, the configurations of the modifications can be combined as appropriate.

[0010] The drawings described in the following embodiments and modifications are schematic, and the ratios of the sizes and thicknesses of the components do not necessarily reflect the actual dimensional ratios.

[0011] A lens 1 (see FIG. 1 ) according to one embodiment is assumed to be applied to, for example, an optical sensor system 100 (see FIG. 5 ). In particular, as an example, the optical sensor system 100 is assumed to be a so-called TOF (Time of Flight) sensor (system) 200 that measures the distance to a measurement object Ob1 from the time of flight of light. The lens 1 is assumed to be applied as a light-receiving lens 7 (see FIG. 5 ) of the TOF sensor 200. However, the use of the lens 1 is not limited to the light-receiving lens 7 of the TOF sensor 200. The lens 1 may also be used as a light-receiving lens of a photoelectric sensor that detects the presence or absence of an object (glass, metal, non-metal, liquid, etc.), changes in the surface condition of the object, etc. Furthermore, the lens 1 may also be used as a lens applied to, for example, a system that irradiates a material with laser light and analyzes material properties from the reflected light, etc.

[0012] As shown in FIG. 1 , lens 1 includes a lens surface region 2 having a lens surface 20 that focuses incident light (e.g., reflected light Op2: see FIGS. 4A and 4B ), and a non-lens surface region 3 where no lens surface 20 is present. In the example shown in FIG. 1 , non-lens surface region 3 has a notch structure V1 in which boundary B1 is recessed inward of lens surface region 2 when viewed along optical axis C1. In other words, when viewed along optical axis C1, a portion of the periphery of lens surface region 2 is recessed (see FIG. 2 ). The “optical axis C1” referred to here is, for example, an axis passing through vertex P1 of first lens surface 21 (described later) and image point J1A of first lens surface 21. FIG. 1 is an external perspective view of lens 1, while FIG. 2 is a front view of lens 1 when viewed along optical axis C1.

[0013] Lens surface 20 has a first lens surface 21, which is a convex lens surface configured as a convex curved surface CV1 including vertex P1, and a second lens surface 22, which is an aspheric surface with a different curvature from that of first lens surface 21. Image point J1B of second lens surface 22 is configured on the same spatial coordinate system as image point J1A of first lens surface 20. That is, both chief ray axes 211 and 222 pass through image point J1 of lens 1 (see FIG. 1). Chief ray axis 222 of second lens surface 22 is configured in a non-coaxial relationship with chief ray axis 211 of first lens surface 21. The "chief ray axis" referred to here is an axis passing through the center of the lens surface and image point J1A of first lens surface 21 and image point J1B of second lens surface 22, and the first lens surface 21 and the second lens surface 22 have different chief ray axes. For convenience, FIG. 4 illustrates the light receiving element 5 at image point J1A of the first lens surface 21 and image point J1B of the second lens surface 22. That is, when lens 1 is applied as optical sensor system 100, axis 211 of the chief ray of the first lens surface 21 and axis 222 of the chief ray of the second lens surface 22 both pass through the light receiving element 5. Note that image points J1, J1A, and J1B shown in FIG. 1 are illustrative illustrations of image points for an object at a certain position, and the positions of these image points may change depending on the distance between lens 1 and the object. However, even if the positions of these image points change, at least axis 222 of the chief ray of the second lens surface 22 and axis 211 of the chief ray of the first lens surface 21 maintain a non-coaxial relationship.

[0014] Also, as an example below, the second lens surface 22 is arranged between the first lens surface 21 and the non-lens surface area 3 so as to follow at least a portion of the boundary B1 between the lens surface area 2 and the non-lens surface area 3 when viewed along the optical axis C1 passing through the vertex P1.

[0015] Lens 1 is configured to have first lens surface 21 and second lens surface 22, and is configured such that axis 222 of the chief ray of second lens surface 22 is non-coaxial with axis 211 of the chief ray of first lens surface 21. Therefore, lens 1 has the advantage of being able to improve the focusing accuracy of incident light over a wider range of distances to lens 1.

[0016] As shown in FIG. 5 , an optical sensor system 100 according to one embodiment includes a light projecting unit 4, the lens 1 (light-receiving lens 7), and a light-receiving element 5. The light projecting unit 4 projects laser light Op1 onto a measurement object Ob1. The lens 1 collects reflected light Op2 from the measurement object Ob1. The light-receiving element 5 receives the light collected by the lens 1 and converts it into an electrical signal. The light-receiving element 5 is disposed so that a light-receiving axis 51 of the light-receiving element 5 coincides with the optical axis C1. The light projecting axis 41 and the light-receiving axis 51 of the light projecting unit 4 are parallel to each other on the optical axis C1. Here, “parallel” does not have to be strictly parallel, and may be offset by, for example, approximately ±10°. This configuration provides an optical sensor system 100 including a lens 1 that can improve the focusing accuracy of incident light over a wider range of distances to the lens 1.

[0017] (Details) (Overall Configuration) The lens 1 and optical sensor system 100 (TOF sensor 200) according to this embodiment will be described in detail below with reference to FIGS. 1 to 8B. In the following description, the X-axis, Y-axis, and Z-axis of the lens 1 are defined as follows. That is, the direction parallel to the optical axis C1 passing through the vertex P1 of the first lens surface 21 is defined as the Z-axis direction. Furthermore, the alignment direction A1 (see FIG. 2) in which the non-lens surface region 3, second lens surface 22, and first lens surface 21 are aligned when viewed along the optical axis C1 (Z-axis direction) is defined as the Y-axis direction. The X-axis direction is perpendicular to each of the Y-axis and Z-axis directions defined in this manner.

[0018] Lens 1 constitutes, for example, a plano-convex lens as a whole. When viewed as a whole, the surface of lens 1 on the positive side of the Z axis has a generally convex shape toward the positive side of the Z axis, and the surface of lens 1 on the negative side of the Z axis has a generally planar shape. However, the surface of lens 1 on the negative side of the Z axis is not limited to a planar shape, and may, for example, have a generally convex shape toward the negative side of the Z axis. Lens 1 has a thickness in the Z axis direction.

[0019] 2 is a front view (as viewed from the positive side of the Z axis) of the lens 1 shown in FIG. 1 , which is a more schematic representation of the lens 1. The lens 1 has a roughly perfect circular shape when viewed from the front. The overall shape of the lens 1 when viewed from the front is not particularly limited, and may be, for example, a long racetrack shape other than a circle.

[0020] 1 and 2, the lens 1 includes a lens surface region 2 and a non-lens surface region 3. As can be seen from Fig. 2, which shows a schematic front view of the lens 1, there is a substantially arc-shaped boundary B1 between the lens surface region 2 and the non-lens surface region 3 when viewed from the positive side of the Z axis.

[0021] The lens surface area 2 has a lens surface 20 that collects light incident from the positive side of the Z axis. When the lens 1 is applied to the TOF sensor 200, the "incident light" referred to here may include "a portion of reflected light Op2" that is formed when the laser light Op1 projected from the light projecting unit 4 is reflected by the surface of the measurement object Ob1 (reflecting surface R1: see FIG. 5). The light incident on the lens 1 is not limited to reflected light.

[0022] In other words, lens surface 20 can be light incident surface 20A (see FIGS. 4A and 4B). On the other hand, the surface opposite lens surface 20 (the surface on the negative side of the Z axis of lens 1) can be light exit surface 20B (see FIGS. 4A and 4B). Optical axis C1 is perpendicular to exit surface 20B.

[0023] Lens surface 20 has first lens surface 21, which is a convex lens surface, and second lens surface 22, which is an aspherical surface. In other words, lens 1 is a divided lens in which lens surface 20 is divided into first lens surface 21 and second lens surface 22. In this embodiment, as an example, it is assumed that first lens surface 21 is an aspherical surface.

[0024] First lens surface 21 is configured as a convex curved surface CV1 including vertex P1. Here, Fig. 6A shows a plano-convex lens 1A having a convex curved surface CV1. Lens 1 has a part of the convex curved surface CV1 of plano-convex lens 1A shown in Fig. 6A as first lens surface 21.

[0025] First lens surface 21 may have, for example, a convex curved surface CV1 defined by the following lens formula (1): In the following lens formula (1), z is the sag amount in a direction parallel to the optical axis C1 (Z-axis direction), C is the curvature, k is the conic constant, r is the radial coordinate, and αi is an aspheric coefficient.

[0026]

[0027] The first lens surface 21 is a lens surface for long distances with respect to the distance to the measurement object Ob1. The first lens surface 21 can be used for medium distances as well as long distances. Hereinafter, the first lens surface 21 may be referred to as the long distance lens surface F1 (see FIGS. 4A and 4B). In this embodiment, the "medium to long distance" refers to a distance L1 (see FIG. 4A) from the lens 1 (e.g., the vertex P1 of the first lens surface 21) to the measurement object Ob1 of approximately 500 mm to 5000 mm. In other words, the first lens surface 21 is configured as a surface capable of focusing reflected light Op2 reflected by the measurement object Ob1 located approximately 5000 mm away from the lens 1 to such an extent that the amount of light received by the light receiving element 5 does not fall below a lower limit (threshold value). The "lower limit value" here refers to, for example, a threshold value that can be set as a value measurable by the TOF sensor 200, such as a light receiving amount of 10 μW. The above numerical value "5000 mm" is an example as a guideline for the "farthest distance" of the "long distance", and is not intended to strictly limit the "farthest distance" of the "long distance".

[0028] The second lens surface 22 has a different curvature from the first lens surface 21. The second lens surface 22 includes a cylindrical lens surface 220 (see FIG. 1). Here, FIG. 6B shows a plano-convex cylindrical lens 1B having an aspherical surface S1 (cylindrical lens surface 220). The lens 1 has a portion of the aspherical surface S1 (cylindrical lens surface 220) of the plano-convex cylindrical lens 1B shown in FIG. 6B as the second lens surface 22. For reference, FIG. 6B illustrates the region of the cylindrical lens surface 220 in the cylindrical lens 1B that is used as the second lens surface 22. Note that the "cylindrical lens 1B" referred to in this disclosure is not limited to a semi-cylindrical shape and may also include the concept of a lens having a lens surface configured as part of a hyperbolic surface. In other words, the aspherical surface S1 is not limited to a strictly semi-cylindrical curved surface.

[0029] Second lens surface 22 may have, for example, an aspherical surface S1 defined by the following lens formula (2): In the following lens formula (2), z is the sag amount in a direction parallel to optical axis C1 (Z-axis direction), C is the curvature, k is the conic constant, and y is the Y-axis coordinate. As described above, the curvature C of aspherical surface S1 of second lens surface 22 is different from the curvature C of first lens surface 21. Note that the following lens formula (2) may include an aspherical coefficient.

[0030]

[0031] The second lens surface 22 is a lens surface for close distances with respect to the distance to the measurement object Ob1. Hereinafter, the second lens surface 22 may also be referred to as the ultra-close distance lens surface F2 (see FIGS. 4A and 4B). In this embodiment, the "ultra-close distance" is assumed to be a distance L1 (see FIG. 4B) from the lens 1 (e.g., the vertex P1 of the first lens surface 21) to the measurement object Ob1 of approximately 50 mm to 500 mm. In other words, the first lens surface 21 is configured as a surface that can focus reflected light Op2 reflected by the measurement object Ob1, which is located approximately 50 mm away from the lens 1, to such an extent that the amount of light received by the light receiving element 5 does not fall below the lower limit (threshold value). Note that the numerical value "50 mm" is merely an example of the "closest distance" of the "ultra-close distance" and is not intended to strictly limit the "closest distance" of the "ultra-close distance."

[0032] The area occupied by the second lens surface 22 relative to the lens surface 20 is smaller than the area occupied by the first lens surface 21 relative to the lens surface 20 .

[0033] Fig. 3 is a sag diagram of the convex curved surface CV1 and aspherical surface S1 of lens 1 in a direction parallel to optical axis C1 (Z-axis direction), with vertex P1 as the origin "0." The x marks in Fig. 3 indicate the position of generatrix D1 (extending in the X-axis direction) on aspherical surface S1 (cylindrical lens surface 220) of second lens surface 22. Note that in Fig. 3, the amount of sag on the vertical axis is normalized by the thickness of lens 1 ("0" to "-1"), and the horizontal axis (Y coordinate) is normalized by the diameter of lens 1 ("-1" to "-1").

[0034] The generatrix direction (a direction of no power, with no curvature) of cylindrical lens surface 220 is parallel to the X-axis. The "generatrix D1" referred to here is a virtual line (with no substance) in the generatrix direction on aspheric surface S1 at a position on aspheric surface S1 that is farthest from a plane on the opposite side of aspheric surface S1, as shown in Fig. 6B . The generatrix direction (X-axis direction) along generatrix D1 (see Fig. 1 ) of cylindrical lens surface 220 intersects (e.g., is perpendicular to) arrangement direction A1 in which non-lens surface region 3, second lens surface 22, and first lens surface 21 are arranged, when viewed along optical axis C1.

[0035] Of the aspherical surface S1 shown in Figure 6B, the portion that is applied as second lens surface 22 of lens 1 corresponds to the range of values ​​0.35 to 0.48 in Figure 3, where the Y coordinate value is normalized by the diameter of lens 1. In other words, second lens surface 22 is configured so as not to include generatrix D1 of cylindrical lens surface 220. In lens 1, second lens surface 22 is disposed adjacent to non-lens surface region 3. Note that the value 0.74 in Figure 3, where the Y coordinate value is normalized by the diameter of lens 1, indicates the position of light projection axis 41 of light projector 4, which will be described later.

[0036] As shown in FIG. 3, the second lens surface 22 is arranged such that the position of the generatrix D1 of the cylindrical lens surface 220 is shifted toward the positive side of the Y axis relative to the vertex P1 of the first lens surface 21 (offset arrangement).

[0037] The non-lens surface region 3 is a region where the lens surface 20 is not present. In this embodiment, the peripheral edge of the lens 1 on the positive side of the Y axis is cut out. Specifically, the lens 1 is provided with a through-hole H1 that penetrates the peripheral edge of the lens 1 in the Z axis direction. The through-hole H1 is open to the outside of the lens 1 when viewed along the optical axis C1 (Z axis direction). In other words, the non-lens surface region 3 has a notch structure V1 in which the boundary B1 is recessed inward of the lens surface region 2 when viewed along the optical axis C1. In the illustrated example, a substantially semicircular through-hole H1 is arranged in the peripheral edge of the lens 1 on the positive side of the Y axis. When viewed along the optical axis C1, the boundary B1 is recessed in a substantially arc-like shape in a direction approaching the vertex P1 (toward the negative side of the Y axis).

[0038] In this embodiment, first lens surface 21 has a chief ray axis 211 that passes through the center of first lens surface 21 and heads toward image point J1A of first lens surface 21 (see FIG. 1 ). Second lens surface 22 has a chief ray axis 222 that passes through the center of second lens surface 22 and heads toward image point J1B of second lens surface 22 (see FIG. 1 ). Image point J1A of first lens surface 21 and image point J1B of second lens surface 22 are configured on the same spatial coordinate system and correspond to image point J1 of lens 1. That is, both chief ray axes 211 and 222 pass through image point J1 of lens 1 (see FIG. 1 ). Here, as shown in FIG. 1 , chief ray axis 222 of second lens surface 22 is configured to be non-coaxial with respect to chief ray axis 211 of first lens surface 21. Furthermore, the second lens surface 22 is disposed between the first lens surface 21 and the non-lens surface region 3 so as to extend along at least a portion of the boundary B1 between the lens surface region 2 and the non-lens surface region 3 when viewed along the optical axis C1 passing through the vertex P1 (see FIG. 2 ). As an example, the second lens surface 22 is formed in a crescent shape that extends along at least a portion of the boundary B1 when viewed along the optical axis C1. In the schematic lens 1 of FIG. 2 , the crescent-shaped second lens surface 22 is disposed along the boundary B1 from both ends B11 and B12 of the arc-shaped boundary B1 in the X-axis direction. However, as shown in FIG. 1 , the second lens surface 22 may be disposed along the boundary B1 on the inside of both ends B11 and B12. The second lens surface 22 is not limited to a crescent shape and may be, for example, half-moon shaped or rectangular shaped. However, by forming the second lens surface 22 in a crescent shape as in this embodiment, it becomes easier to reduce the area occupied by the second lens surface 22 within the lens surface 20. That is, because the propagation distance of light is longer at "long distances" than at "very close distances," reflected light Op2 is more likely to diffuse during propagation through the air. Therefore, it is desirable to ensure that the area occupied by first lens surface 21 (long-distance lens surface F1) is as large as possible so that reflected light Op2 from "long distances" can be collected with maximum efficiency. Therefore, by making the area occupied by second lens surface 22 smaller, the area occupied by first lens surface 21 (long-distance lens surface F1) can be made larger, thereby further improving the collecting accuracy.

[0039] Thus, lens 1 has the advantage of including long-distance lens surface F1 and very close-distance lens surface F2, for example, that the focusing accuracy of incident light can be improved over a wider range of distances from measurement object Ob1 to lens 1. Furthermore, because the generatrix direction (X-axis direction) of second lens surface 22 intersects (e.g., orthogonal to) the arrangement direction A1 in which non-lens surface region 3, second lens surface 22, and first lens surface 21 are arranged when viewed along optical axis C1, second lens surface 22 with improved focusing accuracy can be realized. Furthermore, since second lens surface 22 includes cylindrical lens surface 220, appropriate angle-of-view characteristics can be imparted to incident light, making it easier for light to reach, for example, light receiving element 5 (described later). In particular, since second lens surface 22 is configured not to include generatrix D1 of cylindrical lens surface 220, second lens surface 22 with improved focusing accuracy can be realized.

[0040] In this embodiment, second lens surface 22 is located lower than first lens surface 21 in the Z-axis direction so as to be concave relative to first lens surface 21 (see FIGS. 1 and 3 ). In other words, there is a step in the Z-axis direction between first lens surface 21 and second lens surface 22, and second lens surface 22 is located slightly lower on the negative side of the Z-axis by the amount of this step. However, this is not limited to this, and such a step may not be present. Furthermore, second lens surface 22 may be located higher in the Z-axis direction so as to be convex relative to first lens surface 21.

[0041] 5, the TOF sensor 200 includes a light-projecting unit 4, a light-receiving lens 7 (lens 1), a light-receiving element 5, a light-projecting circuit 101, a light-receiving circuit 102, a control unit 103, and an output unit 104. The TOF sensor 200 further includes one or more mounting substrates (e.g., printed wiring boards) on which the light-projecting unit 4, the light-receiving lens 7, the light-receiving element 5, the light-projecting circuit 101, the light-receiving circuit 102, the control unit 103, and the output unit 104 are mounted, and a housing 105 (see FIG. 5) that houses or holds these components.

[0042] The light-projecting unit 4 projects a laser beam Op1 onto the object to be measured Ob1. The light-projecting unit 4 includes a light-projecting lens 401, a light-projecting element 402 (laser diode) serving as a light source, and a case 403 (see FIGS. 4A and 4B) that houses these components. The light-projecting element 402 is electrically connected to the light-projecting circuit 101 and emits the laser beam Op1 in accordance with a drive command from the light-projecting circuit 101. The light-projecting lens 401 is disposed opposite the light-projecting element 402. The light-projecting unit 4 has an exit surface 4A (see FIGS. 4A and 4B) for emitting the laser beam Op1 to the outside. The exit surface 4A is assumed to be, for example, the lens surface of the light-projecting lens 401 on the positive side of the Z axis. The light-projecting lens 401 is disposed within the case 403 with the exit surface 4A exposed. A light-projection axis 41 of the light-projecting unit 4 is substantially perpendicular to the exit surface 4A.

[0043] In this embodiment, the position of exit surface 4A in the Z-axis direction is substantially the same as the position of vertex P1 of first lens surface 21.

[0044] The wavelength of the laser light Op1 is not particularly limited. As an example, in the present embodiment, it is assumed that the TOF sensor 200 is used in a transport process or the like in a facility such as a factory. Therefore, the laser light Op1 is assumed to be, for example, red visible light with a wavelength of around 660 nm so that a user (e.g., a supervisor in the facility) can visually check the projection position of the laser light Op1.

[0045] In this embodiment, it is assumed that the cross section of the projection spot of the laser light Op1 projected from the light projector 4 on a plane (X-Y plane) perpendicular to the light projection axis 41 is, for example, a perfect circle. That is, for example, if the laser light Op1 is projected from the light projector 4 perpendicularly to the surface (plane) of the measurement object Ob1, it is assumed that a nearly perfect circle projection spot is formed on the surface.

[0046] The light-projecting circuit 101 outputs a drive signal in which the emission intensity and emission time of the laser light Op1 are adjusted based on a control command from the control unit 103 to the light-projecting element 402. The light-projecting element 402 emits (projects) pulsed light (laser light Op1) based on the drive signal.

[0047] The light-receiving lens 7 is the above-mentioned lens 1. The light-receiving lens 7 is disposed in the housing 105 in such a manner that the lens surface 20 is exposed so that the reflected light Op2 from the measurement object Ob1 is incident thereon. The light-receiving lens 7 collects the reflected light Op2 from the measurement object Ob1.

[0048] As shown in FIGS. 4A and 4B , the light receiving element 5 is disposed behind the light receiving lens 7 (on the negative side of the Z axis). The light receiving element 5 receives light focused by the light receiving lens 7 and converts it into an electrical signal (light receiving signal). The light receiving element 5 is, for example, a photodiode. The light receiving element 5 is electrically connected to the light receiving circuit 102 and outputs the light receiving signal to the light receiving circuit 102. The light receiving axis 51 of the light receiving element 5 is, for example, perpendicular to the light receiving surface of the light receiving element 5. The light receiving element 5 is disposed opposite the light receiving surface 20B of the light receiving lens 7 so that the light receiving axis 51 passes through the vertex P1 of the first lens surface 21 of the light receiving lens 7, in other words, so that it coincides with the optical axis C1. The light receiving axis 51 is perpendicular to the light receiving surface 20B.

[0049] Light receiving element 5 is disposed at the focal position of first lens surface 21. As described above, second lens surface 22 is disposed such that the position of generatrix D1 of cylindrical lens surface 220 is shifted to the positive side of the Y axis with respect to vertex P1 of first lens surface 21. Therefore, the focal position of second lens surface 22 is shifted to the positive side of the Y axis from the focal position of first lens surface 21 (position of light receiving element 5).

[0050] Since the higher the frequency response characteristic, the higher the distance detection accuracy of the TOF sensor 200, the smaller the light receiving element 5, the better. In this embodiment, the light receiving element 5 is a micro light receiving element with a width or diameter of the light receiving surface of 1 mm or less, for example. The light projection axis 41 and the light receiving axis 51 of the light projector 4 are parallel to each other along the optical axis C1. The light projection axis 41 and the light receiving axis 51 do not need to be strictly parallel, and may be offset by, for example, about ±10°.

[0051] In this embodiment, the light projection axis 41 and the light reception axis 51 are not coaxial with each other.

[0052] The light receiving circuit 102 includes, for example, an A / D conversion circuit, which converts an analog light receiving signal output from the light receiving element 5 according to the amount of received light into a digital light receiving signal and outputs the digital light receiving signal to the control unit 103.

[0053] The control unit 103 includes a computer system having one or more processors and a memory. At least some of the functions of the control unit 103 are realized by the processor of the computer system executing a program stored in the memory of the computer system. The program may be stored in the memory, provided via a telecommunications line such as the Internet, or provided by being recorded on a non-transitory recording medium such as a memory card. The control unit 103 is electrically connected to the light-emitting circuit 101, the light-receiving circuit 102, and the output unit 104 and controls them.

[0054] Based on the light receiving signal from the light receiving circuit 102, the control unit 103 calculates the time from when the light projecting unit 4 emits laser light Op1 (pulsed light) to when the laser light Op1 is reflected by the measurement object Ob1 and the reflected light Op2 is received by the light receiving element 5. In other words, the control unit 103 calculates the time required for light to travel back and forth between the TOF sensor 200 and the measurement object Ob1. Then, based on the calculation result, the control unit 103 calculates distance data (ranging result) indicating the distance to the measurement object Ob1 and outputs it to the outside from the output unit 104.

[0055] In this embodiment, the light projector 4 is disposed within the non-lens surface region 3. Here, as an example, the case 403 of the light projector 4 has a generally cylindrical shape, and the central axis of the cylinder of the case 403 is generally perpendicular to the light exit surface 4A of the projector lens 401. The central axis of the cylinder of the case 403 generally coincides with the light projection axis 41 of the light projector 4. Meanwhile, the non-lens surface region 3 has generally the same shape as the case 403 when viewed along the Z-axis direction, so that the case 403 fits into the non-lens surface region 3. Because the non-lens surface region 3 has a notch structure V1, when viewed along the Z-axis direction, the peripheral edge of the case 403 on the negative side of the Y-axis is adjacent to and in contact with the inner circumferential surface of the through hole H1 (or may be non-contact with the inner circumferential surface of the through hole H1 with a slight gap). The peripheral edge of the case 403 on the positive side of the Y-axis is exposed to the outside of the lens 1 without facing the inner circumferential surface of the through hole H1. The light projecting unit 4 may be held by the lens 1 by press-fitting the case 403 into the through-hole H1.

[0056] In other words, the light projector 4 and its light projection axis 41 are stably positioned relative to the lens 1 by the non-lens surface area 3 having the cutout structure V1. The light projector 4 may be configured so that at least a portion thereof is movable while being disposed within the non-lens surface area 3 (the direction of movement is not particularly limited). For example, the TOF sensor 200 may have a mechanism that moves the light projector 4 so as to tilt it with respect to the Z-axis direction. The TOF sensor 200 may also have a mechanism that moves the light projector lens 401 in the Z-axis direction.

[0057] Instead of through-hole H1 that penetrates in the Z-axis direction, lens 1 may be provided with a recess as a non-through hole in the Z-axis direction as non-lens surface region 3. The recess may be open on the surface of lens 1 on the negative side of the Z axis and recessed toward the positive side of the Z axis, or may be open on the surface of lens 1 on the positive side of the Z axis and recessed toward the negative side of the Z axis. Light projector 4 may be arranged to fit within the recess (non-lens surface region 3).

[0058] In this way, since the non-lens surface region 3 is provided on the lens 1, by disposing the light projecting unit 4 in the non-lens surface region 3, the light projecting axis 41 and the light receiving axis 51 are positioned closer to each other, which improves the light focusing accuracy of the lens 1 and also enables the device (TOF sensor 200) to be miniaturized in the X-axis and / or Y-axis directions. In particular, since the light projecting unit 4 is disposed adjacent to the second lens surface 22, the amount of light received by the light receiving element 5 can be ensured while reducing the area occupied by the second lens surface 22. As a result, the amount of reflected light Op2 received by the light receiving element 5 can be increased.

[0059] 1 and 3, the generating line D1 of cylindrical lens surface 220 is disposed between light projection axis 41 and light receiving axis 51. That is, second lens surface 22 is disposed offset in the Y-axis direction toward the positive side of the Y-axis with respect to vertex P1 of first lens surface 21. This further improves the light-collection accuracy of light receiving lens 7 (lens 1) for incident light from an "ultra-close distance," and as a result, the amount of light received by light receiving element 5 can be increased.

[0060] (Lens Distance Measurement Characteristics) Next, the distance measurement characteristics of lens 1 will be described with reference to Fig. 7. Fig. 7 is a double logarithmic graph showing the distance measurement characteristics (simulation results) of lens 1 and a lens of a comparative example (hereinafter also referred to as a "single lens"). A single lens, in the case of lens 1, for example, is a plano-convex lens that does not have second lens surface 22, i.e., has only first lens surface 21.

[0061] 7, the horizontal axis represents the detection distance [mm] from the lens (lens 1, single lens) to the reflection point, and the vertical axis represents the amount of light received (arbitrary unit: au) by the light-receiving element 5. In this simulation, rather than irradiating the measurement object Ob1 with laser light and receiving the reflected light with the lens (lens 1, single lens), the measurement object Ob1 was set as the reflection point and the reflection point was set as the light source (for example, a Lambertian light source), and characteristics were verified.

[0062] 7, Q1 indicated by a dashed line represents the distance measurement characteristics using lens 1. Q2 indicated by a solid line represents the distance measurement characteristics using a single lens.

[0063] 7, for a "long distance," the amount of light received by the light receiving element 5 when using the lens 1 is approximately the same as when a single lens is used, and the lens 1 has the same light-gathering accuracy as a single lens. On the other hand, for a "very close distance," particularly at detection distances of around 50 mm to 150 mm, the amount of light received by the light receiving element 5 when using the lens 1 is significantly greater than when a single lens is used, which means that the light-gathering accuracy of the lens 1 is superior.

[0064] In this way, lens 1 focuses incident light from a "long distance" toward light receiving element 5 using the entire lens surface 20 (first lens surface 21 and second lens surface 22), and focuses incident light from an "ultra-close distance" toward light receiving element 5 mainly using second lens surface 22. In other words, second lens surface 22 focuses incident light from an "ultra-close distance" toward light receiving element 5 by bending the light toward the negative side of the Y axis with an angle of view.

[0065] (Application Example of TOF Sensor) Next, an application example of the TOF sensor 200 (optical sensor system 100) will be described with reference to FIGS. 8A and 8B. FIG.

[0066] FIG. 8A is a conceptual diagram of Application Example 1 of the TOF sensor 200. In Application Example 1, the TOF sensor 200 is fixed to a ceiling surface 300 in a facility such as a factory or a logistics warehouse. A conveying device 400, such as a belt conveyor, is disposed directly below the TOF sensor 200. The TOF sensor 200 measures the distance (vertical distance) to workpieces 501, 502, and 503 of different sizes being conveyed by the conveying device 400. The TOF sensor 200 outputs the measurement results (distance data) to an external determination system. The external determination system may perform various processes based on the measurement results. The TOF sensor 200 may be a TOF-type distance image sensor, and in that case, the distance data may be distance image data. The external determination system may perform an inspection process regarding the surface condition of the workpieces 501, 502, and 503 based on the distance image data.

[0067] FIG. 8B is a conceptual diagram of Application Example 2 of the TOF sensor 200. In Application Example 2, the TOF sensor 200 is also installed in a facility such as a factory or a logistics warehouse. The TOF sensor 200 is fixed by a fixture near the diagonal top of the conveying device 400 and measures the distances to workpieces 501, 502, and 503, which vary in size from large to small, from a diagonal direction. The TOF sensor 200 outputs the measurement results (distance data) to, for example, an external determination system. The external determination system can perform a determination process to automatically determine the types of the workpieces 501, 502, and 503 based on the distance data from the diagonal direction. In particular, the external determination system can more accurately determine the type of workpieces using only a single TOF sensor 200 by using the distance data from the diagonal direction.

[0068] (Variation 1-1) Lens 1 according to this variation (variation 1-1) will be described in detail below with reference to Fig. 9A. Hereinafter, with regard to the components of lens 1 according to variation 1-1, components that are substantially common to lens 1 of the above embodiment will be assigned the same reference numerals, and their description may be omitted as appropriate. Note that Fig. 9A, like Fig. 2, shows a schematic front view (as viewed from the positive side of the Z axis) of lens 1 according to variation 1-1.

[0069] Similar to the lens 1 of the above embodiment, the lens 1 of Modification 1-1 has a through-hole H1 penetrating the peripheral portion of the lens 1 in the Z-axis direction, and the non-lens surface region 3 has a notch structure V1 in which the boundary B1 is recessed inward of the lens surface region 2 when viewed along the optical axis C1. However, the lens 1 of Modification 1-1 differs from the lens 1 of the above embodiment in that the second lens surface 22 does not contact the boundary B1. As an example, the second lens surface 22 is formed by a cylindrical lens surface 220 and is circular. In the example of FIG. 9A , the second lens surface 22 is located between the boundary B1 and the vertex P1 so as not to contact the boundary B1.

[0070] It should be noted that the cylindrical lens surface 220 is not limited to being circular. The cylindrical lens surface 220 may be, for example, crescent-shaped or elliptical. For example, FIG. 9B shows a lens 1 according to another example of Modification 1-1. As shown in FIG. 9B, the cylindrical lens surface 220 may be crescent-shaped.

[0071] (Modification 1-2) Lens 1 according to this modification (Modification 1-2) will be described in detail below with reference to Figures 10A and 10B. Below, with regard to the components of lens 1 according to Modification 1-2, components that are substantially the same as those of lens 1 according to the above embodiment will be assigned the same reference numerals, and their description may be omitted as appropriate. Similar to Figure 2, Figures 10A and 10B show schematic front views (as viewed from the positive side of the Z axis) of lens 1 according to Modification 1-2.

[0072] In the above embodiment, the lens 1 is provided with a through-hole H1 that penetrates the peripheral portion of the lens 1 in the Z-axis direction, and the non-lens surface region 3 has a notch structure V1 in which the boundary B1 is recessed inward of the lens surface region 2 when viewed along the optical axis C1. In contrast, in Modification Example 1-2, the through-hole H1 (non-lens surface region 3) with a substantially circular opening is provided inside the peripheral portion of the lens 1, which differs from the lens 1 of the above embodiment. The shape of the opening of the through-hole H1 (non-lens surface region 3) is not limited to a circular shape and may be, for example, an elliptical shape.

[0073] 10A , in lens 1 of modification 1-2, through-hole H1 (non-lens surface region 3) is disposed between vertex P1 and the peripheral edge on the positive side of the Y-axis of lens surface region 2. When viewed along the Z-axis direction, boundary B1 between lens surface region 2 and non-lens surface region 3 is circular, similar to the inner peripheral edge of through-hole H1.

[0074] As shown in FIG. 10A , the lens 1 of modification 1-2 has two second lens surfaces 22. The two second lens surfaces 22 are arranged adjacent to each other on the positive and negative sides of the through hole H1 (non-lens surface region 3) in the Y-axis direction. The two second lens surfaces 22 are each crescent-shaped and arranged symmetrically in the Y-axis direction. For example, the two second lens surfaces 22 are each composed of two surfaces on a common cylindrical lens surface 220 of a single plano-convex cylindrical lens 1B shown in FIG. 6B . However, the two second lens surfaces 22 may each be composed of a portion of the cylindrical lens surface 220 of two different plano-convex cylindrical lenses.

[0075] 10A , vertex P1 of first lens surface 21 is adjacent to second lens surface 22 on the negative side of through-hole H1 (non-lens surface region 3) along the Y axis. However, vertex P1 of first lens surface 21 is not limited to being adjacent to second lens surface 22 on the negative side of the Y axis, and does not have to be adjacent.

[0076] In Modification 1-2, it is also preferable that generatrix D1 of cylindrical lens surface 220 is disposed so as to be shifted from vertex P1 in the Y-axis direction. In Modification 1-2, it is also preferable that two second lens surfaces 22 are configured so as not to include generatrix D1 of cylindrical lens surface 220.

[0077] In Modification 1-2, too, light-projecting unit 4 can be disposed within through-hole H1 (non-lens surface region 3). In Modification 1-2, too, generatrix D1 of cylindrical lens surface 220 can be disposed between light-projecting axis 41 and light-receiving axis 51. In Modification 1-2, too, light-projecting axis 41 and light-receiving axis 51 can be non-coaxially positioned relative to each other.

[0078] 10A shows two second lens surfaces 22, but as shown in Fig. 10B, one second lens surface 22 may be provided on only one of the positive and negative sides of through hole H1 (non-lens surface region 3) along the Y axis. That is, in the example of Fig. 10B, one second lens surface 22 is provided only on the negative side of through hole H1 (non-lens surface region 3) along the Y axis, but it may also be provided only on the positive side.

[0079] (Variation 2) Lens 1 according to this variation (variation 2) will be described in detail below with reference to Fig. 11. Hereinafter, with regard to the components of lens 1 according to variation 2, components that are substantially common to lens 1 of the above embodiment will be assigned the same reference numerals, and their description may be omitted as appropriate. Note that Fig. 11, like Fig. 2, shows a schematic front view of lens 1 according to variation 2 (as viewed from the positive side of the Z axis).

[0080] Modification 2 corresponds to a further modification of Modification 1-2. Through-hole H1 (non-lens surface region 3) having a circular opening is arranged so that the center of the opening coincides with the position of vertex P1 of first lens surface 21 in lens 1 of the above embodiment. In other words, first lens surface 21 of lens 1 in Modification 2 does not include vertex P1 of the above embodiment (vertex P1 is shown in FIG. 11 for reference).

[0081] In Modification 2, generatrix D1 of cylindrical lens surface 220 generally coincides with vertex P1 in the Y-axis direction. In other words, in Modification 2, generatrix D1 of cylindrical lens surface 220 may intersect with light-receiving axis 51 and optical axis C1, but may be offset from these. In Modification 2 as well, it is preferable that two second lens surfaces 22 are configured so as not to include generatrix D1 of cylindrical lens surface 220.

[0082] In Modification 2, too, the light-projecting unit 4 can be disposed within the through-hole H1 (non-lens surface region 3). Modification 2 differs from the above embodiment and Modifications 1-1 and 1-2 in that the light-projecting axis 41 and the light-receiving axis 51 can be coaxial with each other. That is, in Modification 2, the light-projecting axis 41 can also be coaxial with the optical axis C1. In Modification 2, the generatrix D1 of the cylindrical lens surface 220 can intersect with the light-projecting axis 41, but it may also be disposed offset from the light-projecting axis 41 without intersecting with it.

[0083] (Variation 3) Lens 1 according to this variation (variation 3) will be described in detail below with reference to Figures 12A and 12B. Below, with regard to the components of lens 1 according to variation 3, components that are substantially common to lens 1 of the above embodiment will be assigned the same reference numerals, and their description may be omitted as appropriate. Note that, like Figure 2, Figure 12A shows a schematic front view (as viewed from the positive side of the Z axis) of lens 1 according to variation 3.

[0084] Similar to the lens 1 of the above embodiment, the lens 1 of the above embodiment has a through-hole H1 penetrating the peripheral portion of the lens 1 in the Z-axis direction, and the non-lens surface region 3 has a notch structure V1 in which the boundary B1 is recessed inward of the lens surface region 2 when viewed along the optical axis C1. However, the lens 1 of the above embodiment differs from the lens 1 of the above embodiment in that the second lens surface 22 includes a plurality of cylindrical lens surfaces 220. In the example of FIG. 12A , the number of cylindrical lens surfaces 220 is three.

[0085] The three cylindrical lens surfaces 220 are arranged adjacent to each other in order from the boundary B1 toward the negative side of the Y axis. Hereinafter, the cylindrical lens surfaces from the boundary B1 toward the negative side of the Y axis may be referred to as cylindrical lens surfaces 220A, 220B, and 220C.

[0086] As an example, cylindrical lens surfaces 220A, 220B, and 220C are all crescent-shaped. However, cylindrical lens surfaces 220A, 220B, and 220C are set so that their occupation areas relative to lens surface 20 gradually increase in this order. Crescent-shaped cylindrical lens surfaces 220A, 220B, and 220C are formed continuously in this order. The two ends of each crescent-shaped cylindrical lens surface 220A, 220B, and 220C in the X-axis direction are located at approximately the same positions as the two ends B11, B12 of arc-shaped boundary B1 in the X-axis direction, respectively.

[0087] Note that cylindrical lens surfaces 220A, 220B, and 220C are not limited to being crescent-shaped. At least one of cylindrical lens surfaces 220A, 220B, and 220C may be, for example, half-moon shaped or rectangular along the X-axis. For example, FIG. 12B shows lens 1 according to another example of Modification Example 3. As shown in FIG. 12B, cylindrical lens surfaces 220A and 220B may be substantially rectangular along the X-axis, and cylindrical lens surface 220C may be substantially half-moon shaped.

[0088] In lens 1 according to modification 3, the multiple cylindrical lens surfaces 220 have focal points at different positions in the arrangement direction A1 (Y-axis direction). For example, the cylindrical lenses constituting cylindrical lens surface 220A, the cylindrical lenses constituting cylindrical lens surface 220B, and the cylindrical lenses constituting cylindrical lens surface 220C are all different. That is, the generatrix D1 of cylindrical lens surfaces 220A, 220B, and 220C are all different. Cylindrical lens surfaces 220A, 220B, and 220C are formed to have focal points at different positions.

[0089] In other words, in Modification 3, the ultra-short distance lens surface F2 is subdivided. Cylindrical lens surface 220A is set as the ultra-short distance lens surface F2 for when the distance to the measurement object Ob1 is around 50 mm, for example. Cylindrical lens surface 220B is set as the ultra-short distance lens surface F2 for when the distance to the measurement object Ob1 is around 100 mm, for example. Cylindrical lens surface 220C is set as the ultra-short distance lens surface F2 for when the distance to the measurement object Ob1 is around 150 mm, for example. In other words, as an example, the closer the cylindrical lens surface 220 is to the non-lens surface region 3, the more it is set to correspond to reflected light Op2 from the closer measurement object Ob1.

[0090] According to the configuration of the third modification, the accuracy of focusing incident light over a wider distance range is improved.

[0091] (Modification 4) Lens 1 according to this modification (Modification 4) will be described in detail below with reference to FIGS. 13A, 13B, 14A, and 14B. Hereinafter, with regard to components of lens 1 according to Modification 4, components that are substantially common to lens 1 of the above embodiment will be assigned the same reference numerals, and their description may be omitted as appropriate. Similar to FIG. 2, FIGS. 13A and 14A show schematic front views (as viewed from the positive side of the Z axis) of lens 1 according to Modification 4. FIG. 13B shows a cross-sectional view taken along line II-II in FIG. 13A. FIG. 14B shows a cross-sectional view taken along line II-II in FIG. 14A.

[0092] Lens 1 according to Modification 4 differs from lens 1 of the above embodiment in that at least one of first lens surface 21 and second lens surface 22 has Fresnel structure X1. Note that in Modification 4, non-lens surface region 3 has notch structure V1 in which boundary B1 is recessed more deeply inward (toward the negative side of the Y axis) into lens surface region 2 when viewed along optical axis C1, compared to notch structure V1 of lens 1 of the above embodiment (see FIG. 2 ).

[0093] In a lens 1 according to one aspect of Modification 4 shown in FIG. 13A, first lens surface 21 and second lens surface 22 have a first Fresnel structure X11 (X1) and a second Fresnel structure X12, respectively.

[0094] Specifically, as shown in Figures 13A and 13B, first lens surface 21 has a first Fresnel structure X11 that is divided into approximately concentric regions and has a sawtooth cross section like a so-called Fresnel lens. Also, as shown in Figures 13A and 13B, second lens surface 22 has a second Fresnel structure X12 that is divided into approximately concentric regions and has a sawtooth cross section like a Fresnel lens.

[0095] 14A according to another aspect of Modification Example 4, only first lens surface 21 has Fresnel structure X1 (first Fresnel structure X11) among first lens surface 21 and second lens surface 22. Note that only second lens surface 22 may have Fresnel structure X1 among first lens surface 21 and second lens surface 22.

[0096] Thus, according to the configuration of variant example 4, at least one of first lens surface 21 and second lens surface 22 has Fresnel structure X1, which makes it easier to reduce the lens thickness of lens 1 and can also contribute to reducing the material costs of lens 1.

[0097] (Variation 5) Lens 1 according to this variation (variation 5) will be described in detail below with reference to Figures 15A, 15B, and 15C. Hereinafter, with regard to the components of lens 1 according to variation 5, components that are substantially common to lens 1 of the above embodiment will be assigned the same reference numerals, and their description may be omitted as appropriate. Note that, like Figure 2, Figure 15A shows a schematic front view (as viewed from the positive side of the Z axis) of lens 1 according to variation 5.

[0098] The lens 1 according to Modification 5 differs from the lens 1 of the above embodiment in that the second lens surface 22 includes a toroidal lens surface 221 (see FIG. 15A ). Here, FIG. 15B shows a plano-convex toroidal lens 1C having an aspherical surface S1 (toroidal lens surface 221). The lens 1 has a portion of the aspherical surface S1 (toroidal lens surface 221) of the plano-convex toroidal lens 1C shown in FIG. 15B as the second lens surface 22. For example, the curvature of the cross section of the toroidal lens 1C when cut in the Y-Z plane differs from the curvature of the cross section when cut in the X-Z plane (see the portion labeled "with curvature" in FIG. 15B ). For reference, FIG. 15B illustrates the region of the toroidal lens surface 221 used as the second lens surface 22 in the toroidal lens 1C. Also, in Figure 15B, for reference, when lens 1 related to variant example 5 is applied to TOF sensor 200, these axes are illustrated so that the positional relationship of the light projection axis 41 and the light receiving axis 51 with respect to toroidal lens surface 221 and vertex P2 of toroidal lens surface 221 can be understood.

[0099] Similar to second lens surface 22 (cylindrical lens surface 220) in the above embodiment, second lens surface 22 (toroidal lens surface 221) has, for example, a crescent shape in order to reduce the area occupied by second lens surface 22. The positional relationship of second lens surface 22 (toroidal lens surface 221) with respect to non-lens surface region 3 and first lens surface 21 is generally the same as that of second lens surface 22 (cylindrical lens surface 220) in the above embodiment, for example.

[0100] In Modification 5, it is preferable that vertex P2 of toroidal lens surface 221 is positioned offset from vertex P1 (see FIGS. 1 and 2) in the Y-axis direction. As shown in FIG. 15B , vertex P2 of toroidal lens surface 221 can be positioned between light projection axis 41 and light receiving axis 51. In Modification 5, it is preferable that second lens surface 22 is configured so as not to include vertex P2 of toroidal lens surface 221.

[0101] 15C shows a cylindrical lens 1B for easy comparison with the toroidal lens 1C. As shown in FIG. 15C, the cylindrical lens 1B has no curvature in the cross section when cut along the XZ plane.

[0102] In this manner, according to the configuration of Modification 5, second lens surface 22 includes toroidal lens surface 221, and therefore, second lens surface 22 with improved light-collection accuracy can be easily realized.

[0103] It should be noted that the second lens surface 22 is not limited to the cylindrical lens surface 220 and the toroidal lens surface 221, and may include an anamorphic aspherical surface or an xy polynomial surface.

[0104] (Variation 6) The light projector 4 in the optical sensor system 100 (TOF sensor 200) according to this variation (variation 6) will be described in detail below with reference to Fig. 16 and Fig. 17. In the following, with regard to the components of the optical sensor system 100 according to variation 6, components that are substantially common to the optical sensor system 100 of the above embodiment will be assigned the same reference numerals, and descriptions thereof may be omitted as appropriate.

[0105] In the optical sensor system 100 of the above embodiment, the cross section of the projected spot of the laser light Op1 projected from the light projector 4 with respect to a plane (X-Y plane) perpendicular to the light projection axis 41 is a perfect circle. The optical sensor system 100 according to the sixth modification differs from the optical sensor system 100 of the above embodiment in that the cross section K2 (see FIG. 16 ) of the projected spot 6 of the laser light Op1 projected from the light projector 4 with respect to a plane perpendicular to the light projection axis 41 is an ellipse having a major axis 61. The major axis 61 extends along a direction (i.e., the X-axis direction) that is orthogonal to both the arrangement direction A1 in which the non-lens surface region 3, the second lens surface 22, and the first lens surface 21 are aligned and the direction of the light projection axis 41. Beam shaping of the elliptical projected spot 6 with the major axis 61 along the X-axis direction and the circular projected spot 6 can be achieved using an optical system such as an optical filter, for example.

[0106] The inventors of the present application have verified the effectiveness of the light projecting unit 4 projecting laser light Op1 that forms an elliptical projection spot 6 having a major axis 61 along the X-axis direction when the lens 1 is used as the light receiving lens 7.

[0107] Figure 16 is a conceptual diagram showing a cross section K1 of the projected spot 6 in the optical sensor system 100 of the above embodiment, a cross section K2 of the projected spot 6 in the optical sensor system 100 related to variant example 6, and a cross section K3 of the projected spot 6 for comparison.

[0108] 16 has a perfect circular shape. For example, the cross section K1 of the projected light spot 6 at a position a predetermined distance away from the light projecting unit 4 may have a size with a 1:1 ratio with respect to each of the X-axis and Y-axis.

[0109] 16 is a cross section of the light-projected spot 6 in the optical sensor system 100 according to the sixth modification, and has an elliptical shape with a major axis 61 along the X-axis direction. For example, the cross section K2 of the light-projected spot 6 at a position the predetermined distance away from the light-projecting unit 4 may have a size ratio of 5 to 1 with respect to the X-axis and Y-axis, respectively.

[0110] 16 is an ellipse having a major axis 62 along the Y-axis direction. For example, the cross section K3 of the projected light spot 6 at a position the predetermined distance away from the light projector 4 may have a size ratio of 1:5 with respect to the X-axis and Y-axis, respectively.

[0111] The inventors of the present application conducted a simulation in which laser light Op1, which forms the light projection spots 6 on each of the cross sections K1 to K3, was projected perpendicularly onto the surface (flat surface) of a workpiece prepared for verification. The simulation results regarding the amount of reflected light Op2 reflected by the surface of the workpiece and received by the light receiving element 5 are shown in FIG.

[0112] In Fig. 17, the horizontal axis represents the detection distance [mm] from the light-projecting unit 4 to the surface of the workpiece, and the vertical axis represents the amount of light received by the light-receiving element 5 (arbitrary unit: au) versus the detection distance. Note that Fig. 17 is a semi-logarithmic graph with the vertical axis on a logarithmic scale. Fig. 17 shows the characteristics of the amount of light received for detection distances (horizontal axis) of 100 mm to 400 mm.

[0113] The perfect circle (1.1) shown in the upper right column of FIG. 17 corresponds to the projected spot 6 on cross section K1, the ellipse (5.1) corresponds to the projected spot 6 on cross section K2, and the ellipse (1.5) corresponds to the projected spot 6 on cross section K3.

[0114] As can be seen from Figure 17, in the local distance scale range of 100 mm to 400 mm, cross section K1 corresponding to a perfect circle (1.1) and cross section K2 corresponding to an ellipse (5.1) were able to obtain better results than cross section K3 corresponding to an ellipse (1.5).

[0115] Thus, according to the configuration of Modification 6, reflected light Op2 corresponding to light projection spot 6 having an elliptical shape with long axis 61 is more likely to be collected by second lens surface 22 of lens 1. As a result, the amount of light received by light receiving element 5 can be increased. In particular, by forming light projection spot 6 having a cross-sectional shape similar to the shape of second lens surface 22, which is crescent-shaped and long along the X-axis direction, optical sensor system 100 can obtain a good amount of light reception near the near point of 200 mm.

[0116] (Variation 7) Lens 1 according to this variation (variation 7) will be described in detail below with reference to FIGS. 18A and 18B. Hereinafter, with regard to the components of lens 1 according to variation 7 that are substantially the same as those of lens 1 according to the above embodiment, the same reference numerals will be used, and their description may be omitted as appropriate. Similar to FIG. 2, FIG. 18A shows a schematic front view (as viewed from the positive side of the Z axis) of lens 1 according to variation 7. FIG. 18B shows a cross-sectional view taken along line III-III shown in FIG. 18A.

[0117] The lens 1 according to the seventh modification differs from the lens 1 according to the above embodiment in that the lens 1 is configured as a biconvex lens.

[0118] 18A and 18B according to one aspect of Modification Example 7 is configured as a biconvex lens, and therefore has a third lens surface 21X (see FIG. 18B ) with a curvature on the exit surface side of the lens 1 (i.e., the negative side of the Z axis). In other words, third lens surface 21X is the lens surface opposite to first lens surface 21. The curvatures of third lens surface 21X and first lens surface 21 may be the same or different. In the example shown in FIG. 18B , the curvatures of third lens surface 21X and first lens surface 21 are different from each other.

[0119] With lens 1 according to the seventh modification, compared to a single-convex lens such as lens 1 according to the embodiment, the curvature provided by first lens surface 21 can be proportionally distributed to the second lens surface as well, making it possible to design a small curvature for first lens surface 21. This makes it possible to increase the AR efficiency when the surface of lens 1 is coated with an anti-reflection film such as an AR coating.

[0120] (Variation 8) Lens 1 according to this variation (variation 8) will be described in detail below with reference to Figures 19 to 22. Hereinafter, with regard to the components of lens 1 according to variation 8, components that are substantially common to lens 1 of the above embodiment will be assigned the same reference numerals, and their description may be omitted as appropriate. Note that, like Figure 1, Figure 19 shows a schematic external perspective view of lens 1 according to variation 8 as seen from the front side.

[0121] Fig. 20A is a characteristics diagram showing the light intensity distribution on the light receiving surface (see square frame G1) of the light receiving element 5 and its periphery for light transmitted through the lens 1 of the above embodiment (lens 1 shown in Fig. 1) at an arbitrary distance. Fig. 20B is a characteristics diagram showing the light intensity distribution on the light receiving surface (see square frame G1) of the light receiving element 5 and its periphery for light transmitted through the lens 1 of this modification (modification 8). Note that Figs. 20A and 20B are grayscale drawings.

[0122] Fig. 21 shows distance measurement characteristics (simulation results) using the lens 1 of the above embodiment and the lens 1 of this modified example (modified example 8). Like Fig. 7, Fig. 21 is a double logarithmic graph with the horizontal axis representing the detected distance and the vertical axis representing the amount of received light. Distance measurement characteristics Q1 in Fig. 21 show distance measurement characteristics using the lens 1 of the above embodiment and are the same as distance measurement characteristics Q1 in Fig. 7. Distance measurement characteristics Q3 in Fig. 21 show distance measurement characteristics using the lens 1 of modified example 8.

[0123] Fig. 22 shows a plano-convex cylindrical lens 1B having an aspheric surface S1 (cylindrical lens surface 220). Lens 1 according to this modification (modification 8) has a portion of the aspheric surface S1 (cylindrical lens surface 220) of the plano-convex cylindrical lens 1B shown in Fig. 22 as second lens surface 22. For reference, Fig. 22 illustrates the region of cylindrical lens surface 220 that is used as second lens surface 22 in cylindrical lens 1B.

[0124] As shown in FIGS. 19 and 22 , lens 1 according to variant example 8 differs from lens 1 according to the above embodiment in that, when the origin of the coordinate system of the XYZ axes is set so that the generatrix direction along generatrix D1 of cylindrical lens surface 220 intersects the Z axis (see FIG. 22 ), the generatrix direction along generatrix D1 is set to intersect the Y axis, and generatrix D1 appears on the surface of second lens surface 22.

[0125] Specifically, lens 1 according to modification 8 includes cylindrical lens surface 220. The generatrix direction along generatrix D1 of cylindrical lens surface 220 is (substantially) parallel to arrangement direction A1 (i.e., the Y-axis direction) in which non-lens surface region 3, second lens surface 22, and first lens surface 21 are arranged, when viewed along optical axis C1 passing through vertex P1. Second lens surface 22 of lens 1 according to modification 8 is configured to include generatrix D1 of cylindrical lens surface 220 (in FIG. 22 , part of generatrix D1 of cylindrical lens 1B).

[0126] 20A , in the case of lens 1 of the above embodiment, the intensity distribution of light transmitted through second lens surface 22 (cylindrical lens surface 220) appears as a horizontally elongated intensity distribution extending along the X-axis direction with respect to the light-receiving surface. Note that in Fig. 20A , "M1" indicates a spot image originating from first lens surface 21 of lens 1 of the above embodiment, and "M2" indicates a spot image originating from second lens surface 22 of lens 1 of the above embodiment.

[0127] 20B , in the case of lens 1 according to Modification 8, the intensity distribution of light transmitted through second lens surface 22 (cylindrical lens surface 220) appears as a vertically elongated intensity distribution extending along the Y-axis direction with respect to the light-receiving surface. Note that in Fig. 20B , "M3" indicates a spot image originating from first lens surface 21 of lens 1 according to Modification 8, and "M4" indicates a spot image originating from second lens surface 22 of lens 1 according to Modification 8.

[0128] In the lens 1 of the above embodiment, the generating line D1 of the cylindrical lens surface 220 is parallel to the X-axis direction, and therefore the light intensity distribution, which appears horizontally, can move up and down (towards the positive or negative side of the Y-axis) relative to the light-receiving surface as the detection distance varies.

[0129] On the other hand, in lens 1 according to modification 8, generatrix D1 of cylindrical lens surface 220 is parallel to arrangement direction A1 (Y-axis direction) but not parallel to X-axis direction, so the light intensity distribution that appears vertically elongated remains on the light receiving surface regardless of fluctuations in detection distance. That is, in lens 1 according to modification 8, fluctuations in the light intensity distribution with distance are reduced, and as shown in FIG. 21 , fluctuations in the amount of received light with distance in ranging characteristic Q3 are smaller than in ranging characteristic Q1, resulting in a broader waveform. As a result, lens 1 according to modification 8 can be designed so that ranging characteristics are nearly constant regardless of detection distance.

[0130] (Summary) The above-described embodiments and the like disclose the following aspects.

[0131] A lens (1) according to a first aspect includes a lens surface region (2) having a lens surface (20) that focuses incident light (e.g., reflected light Op2), and a non-lens surface region (3) where the lens surface (20) is not present. The lens surface (20) has a first lens surface (21) that is a convex lens surface configured as a convex curved surface (CV1) including a vertex (P1), and a second lens surface (22) that is an aspheric surface and has a different curvature from the first lens surface (21). The axis (222) of a chief ray of the second lens surface (22) is non-coaxial with the axis (211) of a chief ray of the first lens surface (21).

[0132] According to the above aspect, there is an advantage that the focusing accuracy of incident light can be improved over a wider range of distances to the lens (1).

[0133] Regarding the lens (1) according to the second aspect, in the first aspect, the second lens surface (22) is arranged between the first lens surface (21) and the non-lens surface region (3) so as to be along at least a part of the boundary (B1) between the lens surface region (2) and the non-lens surface region (3) when viewed along the optical axis (C1) passing through the vertex (P1).

[0134] According to the above aspect, the focusing accuracy of incident light can be further improved over a wider range of distances to the lens (1).

[0135] Regarding the lens (1) according to the third aspect, in the first or second aspect, the second lens surface (22) includes a cylindrical lens surface (220). A generatrix direction along a generatrix (D1) of the cylindrical lens surface (220) intersects with an arrangement direction (A1) in which the non-lens surface region (3), the second lens surface (22), and the first lens surface (21) are arranged, when viewed along an optical axis (C1) passing through the vertex (P1).

[0136] According to the above aspect, it becomes easier to realize a second lens surface (22) with improved light-collecting accuracy.

[0137] With respect to the lens (1) according to the fourth aspect, in the third aspect, the second lens surface (22) is configured so as not to include the generatrix (D1) of the cylindrical lens surface (220).

[0138] According to the above aspect, it is easier to realize a second lens surface (22) with improved light-collecting accuracy compared to when the second lens surface (22) includes the generatrix (D1).

[0139] In the lens (1) according to the fifth aspect, in the third or fourth aspect, the second lens surface (22) includes a plurality of cylindrical lens surfaces (220). The plurality of cylindrical lens surfaces (220) have focal points at different positions in the arrangement direction (A1).

[0140] According to the above aspect, the accuracy of focusing incident light over a wider distance range is improved.

[0141] Regarding the lens (1) according to the sixth aspect, in any one of the first to fifth aspects, the second lens surface (22) is disposed adjacent to the non-lens surface region (3).

[0142] According to the above aspect, the light-collecting accuracy is further improved.

[0143] With respect to the lens (1) according to the seventh aspect, in any one of the first to sixth aspects, the non-lens surface region (3) has a notch structure (V1) in which the boundary (B1) between the lens surface region (2) and the non-lens surface region (3) is recessed inward of the lens surface region (2) when viewed along the optical axis (C1) passing through the vertex (P1).

[0144] According to the above aspect, for example, by arranging the light projecting portion (4) etc. in the non-lens surface area (3), it is possible to increase the amount of received reflected light (Op2).

[0145] Regarding the lens (1) according to the eighth aspect, in any one of the first to seventh aspects, the second lens surface (22) is formed in a crescent shape along at least a part of the boundary (B1) between the lens surface region (2) and the non-lens surface region (3) when viewed along the optical axis (C1) passing through the vertex (P1).

[0146] According to the above aspect, it becomes easy to reduce the area occupied by the second lens surface (22) among the lens surfaces (20).

[0147] Regarding the lens (1) according to the ninth aspect, in any one of the first to eighth aspects, at least one of the first lens surface (21) and the second lens surface (22) has a Fresnel structure (X1).

[0148] According to the above aspect, it becomes easier to reduce the thickness of the lens (1), and this can also contribute to reducing the material cost of the lens (1).

[0149] Regarding the lens (1) according to the tenth aspect, in any one of the first to ninth aspects, the second lens surface (22) includes a toroidal lens surface (221). The second lens surface (22) is configured not to include a vertex (P2) of the toroidal lens surface (221).

[0150] According to the above aspect, it is easier to realize a second lens surface (22) with improved light-collection accuracy compared to when the second lens surface (22) includes a vertex (P2).

[0151] With respect to the lens (1) according to the eleventh aspect, in the first or second aspect, the second lens surface (22) includes a cylindrical lens surface (220). The generatrix direction along the generatrix (D1) of the cylindrical lens surface (220) is (substantially) parallel to the arrangement direction (A1) of the non-lens surface region (3), the second lens surface (22), and the first lens surface (21) when viewed along the optical axis (C1) passing through the vertex (P1). The second lens surface (22) is configured to include the generatrix (D1) of the cylindrical lens surface (220).

[0152] According to the above aspect, a portion of the light that passes through the second lens surface (22) continues to reach the image point (J1) regardless of the detection distance, making it possible to design distance measurement characteristics that are nearly constant regardless of the detection distance.

[0153] Regarding the lens (1) according to the twelfth aspect, in any one of the first to eleventh aspects, the lens (1) is configured as a biconvex lens and further has a third lens surface (21X) having a curvature on the exit surface.

[0154] According to the above aspect, it is possible to design the curvature of the first lens surface (21) to be small, and the efficiency of the anti-reflection film coated on the surface of the lens (1) can be increased.

[0155] An optical sensor system (100) according to a thirteenth aspect includes a light projecting unit (4), the lens (1) according to any one of the first to twelfth aspects, and a light receiving element (5). The light projecting unit (4) projects laser light (Op1) onto a measurement object (Ob1). The lens (1) collects reflected light (Op2) from the measurement object (Ob1). The light receiving element (5) receives the light collected by the lens (1) and converts it into an electrical signal. The light receiving element (5) is disposed so that the light receiving axis (51) of the light receiving element (5) coincides with an optical axis (C1) passing through the vertex (P1). The light projecting axis (41) and the light receiving axis (51) of the light projecting unit (4) are parallel to each other along the optical axis (C1).

[0156] According to the above aspect, it is possible to provide an optical sensor system (100) equipped with a lens (1) that can improve the focusing accuracy of incident light over a wider range of distances to the lens (1).

[0157] Regarding the optical sensor system (100) according to the fourteenth aspect, in the thirteenth aspect, the first lens surface (21) is a lens surface for a long distance with respect to the distance to the measurement object (Ob1), and the second lens surface (22) is a lens surface for a short distance with respect to the distance to the measurement object (Ob1).

[0158] According to the above aspect, when the distance to the measurement object (Ob1) is a “long distance,” light is accurately focused by the first lens surface (21), and when the distance to the measurement object (Ob1) is a “short distance,” light is accurately focused by the second lens surface (22). As a result, the amount of light received by the light-receiving element (5) can be increased.

[0159] With regard to the optical sensor system (100) according to the fifteenth aspect, in the thirteenth or fourteenth aspect, the light projecting section (4) is arranged in the non-lens surface area (3).

[0160] According to the above aspect, the light projection axis (41) and the light receiving axis (51) are positioned closer to each other, which improves the light focusing accuracy of the lens (1). As a result, the amount of light received by the light receiving element (5) can be increased.

[0161] Regarding the optical sensor system (100) according to the sixteenth aspect, in any one of the thirteenth to fifteenth aspects, the second lens surface (22) includes a cylindrical lens surface (220) or a toroidal lens surface (221). A generatrix (D1) of the cylindrical lens surface (220) or a vertex (P2) of the toroidal lens surface (221) is disposed between the light projection axis (41) and the light receiving axis (51).

[0162] According to the above aspect, in other words, the second lens surface (22) is offset from the vertex (P1) of the first lens surface (21). This improves the light-collecting accuracy of the lens (1). As a result, the amount of light received by the light-receiving element (5) can be increased.

[0163] With regard to the optical sensor system (100) according to the seventeenth aspect, in any one of the thirteenth to sixteenth aspects, the light projection axis (41) and the light receiving axis (51) are in a non-coaxial positional relationship with each other.

[0164] According to the above aspect, the light-collecting accuracy of the lens (1) is improved compared to when the light-projecting axis (41) and the light-receiving axis (51) are coaxial with each other, and as a result, the amount of light received by the light-receiving element (5) can be increased.

[0165] Regarding the optical sensor system (100) according to the eighteenth aspect, in any one of the thirteenth to seventeenth aspects, a cross section of a projected spot (6) of laser light (Op1) projected from a light projecting unit (4) with respect to a plane perpendicular to a light projection axis (41) is elliptical in shape having a major axis (61). The major axis (61) is along a direction orthogonal to both an arrangement direction (A1) in which the non-lens surface region (3), the second lens surface (22), and the first lens surface (21) are aligned and the direction of the light projection axis (41).

[0166] According to the above aspect, the reflected light (Op2) corresponding to the elliptical projected light spot (6) having the major axis (61) is easily collected by the second lens surface (22) of the lens (1), which can result in an increase in the amount of light received by the light receiving element (5).

[0167] The configurations according to the second to twelfth aspects are not essential for the lens 1 and may be omitted as appropriate. The configurations according to the fourteenth to eighteenth aspects are not essential for the optical sensor system 100 and may be omitted as appropriate.

[0168] REFERENCE SIGNS LIST 1 Lens 2 Lens surface area 20 Lens surface 21 First lens surface 211 Axis of chief ray 22 Second lens surface 220 Cylindrical lens surface 221 Toroidal lens surface 222 Axis of chief ray 3 Non-lens surface area 4 Light projecting section 41 Light projecting axis 5 Light receiving element 51 Light receiving axis 6 Light projecting spot 61 Long axis 100 Optical sensor system A1 Arrangement direction B1 Boundary C1 Optical axis CV1 Convex curved surface D1 Generatrix (of cylindrical lens surface) Ob1 Measurement object Op1 Laser light Op2 Reflected light P1 Vertex P2 Vertex (of toroidal lens surface) V1 Notch structure X1 Fresnel structure

Claims

1. The optical element includes a lens surface area having a lens surface that collects incident light, and a non-lens surface area where the lens surface is not present, The lens surface is a first lens surface that is a convex lens surface and is configured as a convex curved surface including a vertex; a second lens surface that is an aspheric surface and has a curvature different from that of the first lens surface; and the axis of the chief ray of the second lens surface is non-coaxial with the axis of the chief ray of the first lens surface; lens.

2. The second lens surface is When viewed along an optical axis passing through the vertex, the lens surface region is disposed between the first lens surface and the non-lens surface region along at least a part of the boundary between the lens surface region and the non-lens surface region. The lens of claim 1 .

3. the second lens surface includes a cylindrical lens surface; a generatrix direction along a generatrix of the cylindrical lens surface intersects with an arrangement direction in which the non-lens surface region, the second lens surface, and the first lens surface are arranged, when viewed along an optical axis passing through the vertex. The lens of claim 1 .

4. the second lens surface is configured so as not to include the generatrix of the cylindrical lens surface. The lens of claim 3.

5. the second lens surface includes a plurality of the cylindrical lens surfaces, the plurality of cylindrical lens surfaces have focal points at different positions in the arrangement direction; The lens of claim 3.

6. the second lens surface is disposed adjacent to the non-lens surface area; The lens of claim 1 .

7. the non-lens surface region has a notch structure in which the boundary between the lens surface region and the non-lens surface region is recessed inward of the lens surface region when viewed along an optical axis passing through the vertex; The lens of claim 1 .

8. the second lens surface is formed in a crescent shape along at least a part of the boundary between the lens surface region and the non-lens surface region when viewed along an optical axis passing through the vertex. The lens of claim 1 .

9. At least one of the first lens surface and the second lens surface has a Fresnel structure. The lens of claim 1 .

10. the second lens surface includes a toroidal lens surface; The second lens surface is configured so as not to include the vertex of the toroidal lens surface. The lens of claim 1 .

11. the second lens surface includes a cylindrical lens surface; a generatrix direction of the cylindrical lens surface along a generatrix thereof is parallel to an arrangement direction of the non-lens surface region, the second lens surface, and the first lens surface, when viewed along an optical axis passing through the vertex; the second lens surface is configured to include the generatrix of the cylindrical lens surface. The lens of claim 1 .

12. a light projecting unit that projects laser light onto an object to be measured; 12. The lens according to claim 1, comprising: the lens configured to collect reflected light from the object to be measured; a light receiving element that receives the light collected by the lens and converts it into an electrical signal; Equipped with the light-receiving element is disposed so that a light-receiving axis of the light-receiving element coincides with an optical axis passing through the vertex; The light-projecting axis of the light-projecting unit and the light-receiving axis are parallel to each other on the optical axis. Optical sensor system.

13. the first lens surface is a lens surface for a long distance with respect to the distance to the measurement object, the second lens surface is a lens surface for a short distance with respect to the distance to the measurement object; The optical sensor system of claim 12.

14. The light projecting unit is disposed within the non-lens surface area. The optical sensor system of claim 12.

15. the second lens surface includes a cylindrical lens surface or a toroidal lens surface; a generatrix of the cylindrical lens surface or a vertex of the toroidal lens surface is disposed between the light projection axis and the light receiving axis; The optical sensor system of claim 12.

16. The light projection axis and the light receiving axis are in a non-coaxial positional relationship with each other. The optical sensor system of claim 12.

17. a cross section of a projection spot of the laser beam projected from the light projecting unit with respect to a plane perpendicular to the projection axis is an ellipse having a major axis, the long axis is along a direction perpendicular to each of an arrangement direction of the non-lens surface area, the second lens surface, and the first lens surface and a direction of the light projection axis; The optical sensor system of claim 12.